Apparatus and method for charging a DC battery

• US 5,771,165 A
• Filed: 08/06/1997
• Issued: 06/23/1998
• Est. Priority Date: 06/05/1996
• Status: Expired due to Fees

• Current Assignee: Hydro-Quebec (Province of Québec)
• Original Assignee: Hydro-Quebec (Province of Québec)
• Inventors: Slimani, Karim, Couture, Pierre, Francoeur, Bruno
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): HAN, YOUNGHUIE JESSICA
• Application Number:
  US08/904,583
• Time in Patent Office: 321 Days
• Field of Search: 363/16, 363/17, 363/24, 363/39, 363/41, 363/97, 363/98, 363/131, 363/132, 363/136, 323/222, 323/225, 323/229, 323/332, 323/335, 323/338, 320/140, 320/DIG. 28
• US Class Current: 363/97
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: H02J 7/06 using discharge tubes or semiconductor devices
• CPC Class Codes: H02M 1/0085 Partially controlled bridges
• CPC Class Codes: H02M 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
• CPC Class Codes: Y10S 320/28 Regulating transformer, e.g. high leakage, ferro-resonant

Abstract

The battery charger including a power factor correcting and voltage regulating apparatus having an inductor through which current is modulated by a modulator to obtain an efficient regulation and an efficient power factor correction. According to a first embodiment, the modulator comprises two rectifying elements connected to two controllable high frequency bidirectional switch elements. According to a second embodiment, the modulator comprises a rectifying element connected to a controllable high frequency switch. According to a third embodiment, an efficient battery charger is provided. It comprises an inverter including four controllable high frequency bidirectional switch elements connected in a bridge configuration. According to a fourth embodiment, a two-part battery charger is provided. It has an indicator for indicating quality of the coupling between the two parts thereof. According to a fifth embodiment, a two-part battery charger is provided. It has the necessary means for detecting the voltage delivered at the terminals of the battery and using it for controlling its operation.

Claims

1. A separable two-part battery charger for supplying a direct current signal to battery connect terminals, comprising a first part and a second part, wherein:

the first part includes;

a secondary winding of an impedance matching transformer, having an output for delivering a transformed alternating current signal;

a first magnetic core part of the impedance matching transformer, which is magnetically coupled to the secondary winding;

a current rectifier for rectifying the transformed alternating current signal and delivering a rectified current signal; and

a low pass filter means for low pass filtering the rectified current signal to supply the direct current signal to the battery connect terminals; and

the second part includes;

a power supply means for producing a DC output voltage signal;

an inverter resonant circuit means for inverting the DC output voltage signal and delivering an alternating current signal;

a primary winding of the impedance matching transformer, having an input for receiving the alternating current signal;

a second magnetic core part of the impedance matching transformer, which is magnetically coupled to the first primary winding, the second magnetic core part being mechanically connectable to the first magnetic core part;

a current detector for detecting a current flowing through the inverter resonant circuit means and delivering a current signal indicative of the current flowing through the inverter resonant circuit means;

a current averaging means for averaging the current signal delivered by the current detector and delivering an average current signal;

a comparing means for comparing the average current signal to a current reference signal and delivering a signal indicative of a difference between the average current signal and the current reference signal, the difference being representative of quality of mechanical coupling between the first and second magnetic core parts; and

an indicator for indicating to a user the quality of mechanical coupling between the first and second magnetic core parts, the indicator having an input for receiving the signal delivered from the comparing means.

2. A charger according to claim 1, wherein:

the power supply means is a voltage regulating means for producing the DC output voltage signal from an AC power supply signal;

the inverter resonant circuit means comprises;

an inverter means for inverting the DC output voltage signal and delivering a square voltage signal, the inverter means including four controllable high frequency bidirectional switch elements connected in a bridge configuration having two opposite input ends for receiving the DC output voltage signal, and two other opposite output ends for supplying the square voltage signal, each of the four switch elements having a gate for receiving a switch control signal at a controlled frequency determining the direct current signal supplied to the battery connect terminals; and

a resonant circuit having an input for receiving the square voltage signal and an output for delivering the alternating current signal;

the charger further comprising;

a voltage detecting means for detecting the DC output voltage signal and delivering a voltage signal indicative of the DC output voltage signal;

a controlling means for controlling the four switch elements, the controlling means including;

the current averaging means;

multiplying means for multiplying the voltage signal delivered by the voltage detecting means by the average current signal delivered by the current averaging means and delivering a battery power signal indicative of a power supplied to the battery connect terminals;

a regulating means for comparing the battery power signal to a reference power signal and delivering a value representative of a difference between the battery power signal and the reference power signal; and

an oscillator having an output for delivering the switch control signals at the controlled frequency as a function of the value delivered by the regulating means.

3. A charger according to claim 2, wherein the voltage detecting means is a voltage divider having two resistors connected in series.

4. A charger according to claim 2, wherein the resonant circuit comprises a capacitor and an inductor connected in series.

5. A charger according to claim 2, wherein:

the current rectifier includes four diodes connected according to a diode bridge configuration having an output; and

the low pass filter means comprises a capacitor connected in parallel to the output of the diode bridge configuration, and an inductance connected in series to the battery connect terminals.

6. A charger according to claim 2, wherein the controlling means further comprises:

a frequency limiter having an input connected to the output of the oscillator, and an output for delivering the switch control signals at the controlled frequency which is limited under a predetermined threshold value; and

a driver having an input connected to the output of the limiter, and outputs connected to the gates of the four controllable high frequency bidirectional switch elements.

7. An apparatus according to claim 2, further comprising a tertiary winding of the impedance matching transformer, which is magnetically coupled to the primary and secondary windings, the tertiary winding being for delivering a voltage signal indicative of a voltage at the battery connect terminals;

and

wherein the controlling means further comprises;

a peak voltage detector for detecting a peak voltage of the signal delivered by the tertiary winding and delivering a peak signal representative of the peak voltage of the signal delivered by the tertiary winding;

comparing means for comparing the peak signal delivered by the peak voltage detector to a predetermined threshold signal, and delivering an output signal when the peak signal reaches the threshold signal, the output signal of the comparing means preventing operation of the oscillator.

8. An apparatus according to claim 1, wherein the power supply means is a voltage regulating means comprising:

an apparatus input for receiving an AC power supply signal having a frequency and a peak value;

a first low pass filter having an input connected to the apparatus input for low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input, the low pass filter having also an output;

an inductor connected to the output of the low pass filter;

a rectifying-modulating bridge circuit means for modulating an alternating current flowing through the inductor at a frequency higher than the one of the AC power supply signal, rectifying this alternating current, and delivering a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal, the bridge circuit means including two rectifying elements connected respectively to two controllable high frequency bidirectional switch elements to form a pair of boost converters, each of the switch elements having a gate for receiving a switch control signal;

a second low pass filter for filtering alternating voltage components out of the regulated voltage signal, the second low pass filter having an output for delivering the DC output voltage signal; and

voltage detecting means for detecting the DC output voltage signal, the voltage detecting means having an output for delivering an output signal indicative of a value of the DC output voltage signal; and

a controlling means for controlling the switch elements to regulate the DC output voltage signal at a desired voltage signal by producing a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal, the controlling means including;

a comparator for comparing the output signal of the voltage detecting means to a reference voltage signal and delivering a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

a pulse width modulator for producing the switch control signals as a function of the signal delivered by the comparator means.

9. An apparatus according to claim 1, wherein:

the inverter resonant circuit means includes controllable high frequency bidirectional switch elements, each of the switch elements having a gate for receiving a switch control signal at a controlled frequency determining the direct current signal supplied to the battery connect terminals;

the second part includes;

a tertiary winding of the impedance matching transformer, which is magnetically coupled to the second magnetic core part, the tertiary winding being for delivering a voltage signal indicative of a voltage at the battery connect terminals; and

a controller for controlling the switch elements as a function of the voltage signal delivered by the tertiary winding.

10. An apparatus according to claim 1, wherein the power supply means is a voltage regulating means comprising:

an apparatus input for receiving an AC power supply signal having a frequency and a peak value;

a first low pass filter for low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input;

rectifying means for rectifying an AC signal delivered from the first low pass filter, the rectifying means having an output for delivering a rectified voltage signal;

an inductor connected in series to the output of the rectifying means;

modulating means for modulating a current flowing through the inductor to produce a modulated alternating current through the inductor at a frequency higher than the one of the AC power supply signal and to produce a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal, the modulating means including a rectifying element connected to a controllable high frequency switch means to form a boost converter, the controllable high frequency switch means having a gate for receiving a switch control signal;

a second low pass filter for filtering alternating voltage components out of the regulated voltage signal, and delivering the DC output voltage signal; and

a voltage detecting means for detecting the DC output voltage signal and delivering an output signal indicative of the DC output voltage signal;

controlling means for controlling the controllable high frequency switch means to regulate the DC output voltage signal at a desired voltage signal by producing a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal, the controlling means including;

a comparator for comparing the output signal of the voltage detecting means to a reference voltage signal and delivering a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

a pulse width modulator for producing the at least one control signal as a function of the signal delivered by the comparator.

11. A battery charger for supplying a direct current signal to battery connect terminals, comprising:

a power supply means for producing a DC output voltage signal;

an inverter means for inverting the DC output voltage signal and delivering a square voltage signal, the inverter means including four controllable high frequency bidirectional switch elements connected in a bridge configuration having two opposite input ends for receiving the DC output voltage signal, and two other opposite output ends for supplying the square voltage signal, each of the four switch elements having a gate for receiving a switch control signal at a controlled frequency determining the direct current signal supplied to the battery connect terminals;

a voltage detecting means for detecting the DC output voltage signal and delivering a voltage signal indicative of the DC output voltage signal;

a current detector for detecting a current signal at the input ends of the bridge configuration and delivering a signal indicative of the current signal;

a controlling means for controlling the four switch elements, the controlling means including;

a current averaging means for averaging the signal delivered by the current detector and delivering an average current signal indicative of an average value of the current signal;

multiplying means for multiplying the voltage signal delivered by the voltage detecting means by the average current signal delivered by the current averaging means and delivering a battery power signal indicative of a power supplied to the battery connect terminals;

a regulating means for comparing the battery power signal to a reference power signal and delivering a signal representative of a difference between the battery power signal and the reference power signal; and

an oscillator having an output for delivering the switch control signals at the controlled frequency as a function of the signal delivered by the regulating means;

a resonant circuit having an input for receiving the square voltage signal and an output for producing an alternating current signal;

an impedance matching transformer having a primary winding for receiving the alternating current signal, and a secondary winding for delivering a transformed alternating current signal;

a current rectifier for rectifying the transformed alternating current signal and delivering a rectified current signal; and

a low pass filter means for low pass filtering the rectified current signal and delivering the direct current signal supplied to the battery connect terminals.

12. A charger according to claim 11, wherein the voltage detecting means is a voltage divider having two resistors connected in series.

13. A charger according to claim 11, wherein the resonant circuit comprises a capacitor and an inductor connected in series.

14. A charger according to claim 11, wherein:

the current rectifier includes four diodes connected according to a diode bridge configuration having an output; and

the low pass filter means comprises a capacitor connected in parallel to the output of the diode bridge configuration, and an inductance connected in series to the battery connect terminals.

15. A charger according to claim 11, wherein the controlling means comprises:

a frequency limiter having an input connected to the output of the oscillator, and an output for delivering the switch control signals at a frequency which is limited under a predetermined threshold value; and

a driver having an input connected to the output of the limiter, and outputs connected to the gates of the four controllable high frequency bidirectional switch elements.

16. An apparatus according to claim 11, wherein the power supply means is a voltage regulating means for producing the DC output voltage signal from an AC power supply signal, and the voltage regulating means comprises:

an apparatus input for receiving the AC power supply signal having a frequency and a peak value;

a first low pass filter having an input connected to the apparatus input for low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input, the low pass filter having also an output;

an inductor connected to the output of the low pass filter;

a rectifying-modulating bridge circuit means for modulating an alternating current flowing through the inductor at a frequency higher than the one of the AC power supply signal, rectifying this alternating current, and delivering a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal, the bridge circuit means including two rectifying elements connected respectively to two controllable high frequency bidirectional switch elements to form a pair of boost converters, each of the switch elements having a gate for receiving a switch control signal;

a second low pass filter for low pass filtering alternating voltage components out of the regulated voltage signal, the second low pass filter having an output for delivering the DC output voltage signal; and

a voltage detector for detecting the DC output voltage signal, the voltage detector having an output for delivering an output signal indicative of the DC output voltage signal; and

a controller for controlling the switch elements to regulate the DC output voltage signal at a desired voltage signal by producing a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal, the controller including;

a comparing means for comparing the output signal of the voltage detector to a reference voltage signal and delivering a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

a pulse width modulator for producing the switch control signals as a function of the signal delivered by the comparing means.

17. An apparatus according to claim 11, comprising a first part and a second part, wherein:

the first part includes;

the secondary winding of the impedance matching transformer;

a first magnetic core part of the impedance matching transformer, which is magnetically coupled to the secondary winding;

the current rectifier; and

the low pass filter means; and

the second part includes;

the power supply means;

the inverter means;

the voltage detecting means;

the current detector;

the controlling means;

the resonant circuit;

the primary winding of the impedance matching transformer;

a second magnetic core part of the impedance matching transformer, which is magnetically coupled to the first primary winding, the second magnetic core part being mechanically connectable to the first magnetic core part;

a comparing means for comparing the average current signal to a current reference signal and delivering a signal indicative of a difference between the average current signal and the current reference signal, the difference being representative of quality of mechanical coupling between the first and second magnetic core parts; and

an indicator for indicating to a user the quality of mechanical coupling between the first and second magnetic core parts, the indicator having an input for receiving the signal delivered from the comparing means.

18. An apparatus according to claim 11, comprising a first part and a second part, wherein:

the first part includes;

the secondary winding of the impedance matching transformer;

a first magnetic core part of the impedance matching transformer, which is magnetically coupled to the secondary winding;

the current rectifier; and

a low pass filter means; and

the second part includes;

the power supply means;

the inverter means;

the voltage detecting means;

the current detector;

the controlling means;

the resonant circuit;

the primary winding of the impedance matching transformer;

a second magnetic core part of the impedance matching transformer, which is magnetically coupled to the first primary winding, the second magnetic core part being mechanically connectable to the first magnetic core part;

a tertiary winding of the impedance matching transformer, which is magnetically coupled to the second magnetic core part, the tertiary winding being for delivering a voltage signal indicative of a voltage at the battery connect terminals; and

a controller for controlling the switch elements as a function of the voltage signal delivered by the tertiary winding.

19. An apparatus according to claim 11, wherein the power supply means is a voltage regulating means comprising:

an apparatus input for receiving an AC power supply signal having a frequency and a peak value;

a first low pass filter for low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input;

rectifying means for rectifying an AC signal delivered from the first low pass filter, the rectifying means having an output for delivering a rectified voltage signal;

an inductor connected in series to the output of the rectifying means;

modulating means for modulating a current flowing through the inductor to produce a modulated alternating current through the inductor at a frequency higher than the one of the AC power supply signal and to produce a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal, the modulating means including a rectifying element connected to a controllable high frequency switch means to form a boost converter, the controllable high frequency switch means having a gate for receiving a switch control signal;

a second low pass filter for low pass filtering alternating voltage components out of the regulated voltage signal, and delivering the DC output voltage signal;

a voltage detector for detecting the DC output voltage signal and delivering an output signal indicative of the DC output voltage signal; and

a controller for controlling the controllable high frequency switch means to regulate the DC output voltage signal at a desired voltage signal by producing a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal, the controller including;

a comparing means for comparing the output signal of the voltage detector to a reference voltage signal and delivering a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

a pulse width modulator for producing the switch control signal as a function of the signal delivered by the comparing means.

20. A method for supplying a direct current signal to battery connect terminals, comprising steps of:

(a) supplying a DC output voltage signal;

(b) inverting the DC output voltage signal to produce a square voltage signal by means of an inverter means including four controllable high frequency bidirectional switch elements connected in a bridge configuration having two opposite input ends for receiving the DC output voltage signal, and two other opposite output ends for supplying the square voltage signal, each of the four switch elements having a gate for receiving a switch control signal at a controlled frequency determining the direct current signal supplied to the battery connect terminals;

(c) detecting the DC output voltage signal to produce an average voltage signal indicative of the DC output voltage signal;

(d) detecting a current signal at the input ends of the bridge configuration to produce an average current signal indicative of an average value of the current signal;

(e) controlling the four switch elements by means of the following steps;

(i) multiplying the average voltage signal by the average current signal to produce a battery power signal indicative of a power supplied to the battery connect terminals;

(ii) comparing the battery power signal, to a reference power signal to produce a signal representative of a difference between the battery power signal and the reference power signal; and

(iii) producing the switch control signals at the controlled frequency as a function of the signal produced in step (ii);

(f) applying the square voltage signal to an input of a resonant circuit to produce at its output an alternating current signal;

(g) applying the alternating current signal to a primary winding of an impedance matching transformer to deliver at its secondary winding a transformed alternating current signal;

(h) rectifying the transformed alternating current signal to produce a rectified current signal; and

(j) low pass filtering the rectified current signal to produce the direct current signal supplied to the battery connect terminals.

21. A method according to claim 20, wherein step (e) further comprises step of (iv) limiting the controlled frequency of the switch control signals under a predetermined threshold value.

22. A method according to claim 20, wherein the step (a) is a step of regulating an AC power supply signal to produce the DC output voltage signal and comprises steps of:

(A) receiving by means of an apparatus input the AC power supply signal having a frequency and a peak value;

(B) low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input by means of a low pass filter means having an input connected to the apparatus input, and an output;

(C) providing an inductor connected to the output of the low pass filter means;

(D) modulating an alternating current flowing through the inductor at a frequency higher than the one of the AC power supply signal, and rectifying this alternating current to deliver a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal by means of a rectifying-modulating bridge circuit means, the bridge circuit means including two rectifying elements connected respectively to two controllable high frequency bidirectional switch elements to form a pair of boost converters, each of the switch elements having a gate for receiving a switch control signal;

(E) low pass filtering alternating voltage components out of the regulated voltage signal, and delivering the DC output voltage signal; and

(F) controlling the switch elements to produce a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal to regulate the DC output voltage signal at a desired voltage signal, the step (F) further including steps of;

(I) detecting the DC output voltage signal delivered from step (E), and delivering an output signal indicative of the DC output voltage signal;

(II) comparing the output signal delivered in step (I) to a reference voltage signal to produce a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

(III) producing the switch control signals by means of a pulse width modulator as a function of the signal produced from step (II).

23. A method according to claim 20, further comprises the steps of:

(A) providing a first part which includes;

the secondary winding of the impedance matching transformer;

a first magnetic core part of the impedance matching transformer, which is magnetically coupled to the secondary winding;

a current rectifier for performing step (h); and

a low pass filter means for performing step (j);

(B) providing a second part which includes;

a voltage regulating means for performing step (a);

an inverter resonant circuit means for performing steps (b) to (f);

the primary winding of the impedance matching transformer;

a second magnetic core part of the impedance matching transformer, which is magnetically coupled to the first primary winding, the second magnetic core part being mechanically connectable to the first magnetic core part;

(C) detecting a current flowing through the inverter resonant circuit means and delivering a current signal indicative of the current flowing through the inverter resonant circuit means;

(D) averaging the current signal delivered from step (C) and delivering an average current signal;

(E) comparing the average current signal to a current reference signal and delivering a signal indicative of a difference between the average current signal and the current reference signal, the difference being representative of quality of mechanical coupling between the first and second magnetic core parts; and

(F) indicating to a user the quality of mechanical coupling between the first and second magnetic core parts, based on the signal delivered from step (E).

24. A method according to claim 20, further comprising steps of:

(A) providing a first part which includes;

the secondary winding of the impedance matching transformer;

a first magnetic core part of the impedance matching transformer, which is magnetically coupled to the secondary winding;

a current rectifier for performing step (h); and

a low pass filter means for performing step (j);

(B) providing a second part which includes;

a voltage regulating means for performing step (a);

the inverter means;

a voltage detecting means for performing step (c);

a current detector for performing step (d);

a controlling means for performing step (e);

the resonant circuit;

the primary winding of the impedance matching transformer;

a second magnetic core part of the impedance matching transformer, which is magnetically coupled to the first primary winding, the second magnetic core part being mechanically connectable to the first magnetic core part;

a tertiary winding of the impedance matching transformer, which is magnetically coupled to the second magnetic core part, the tertiary winding being for delivering a voltage signal indicative of a voltage at the battery connect terminals; and

(C) controlling the switch elements as a function of the voltage signal.

25. A method according to claim 20, wherein step (a) comprises steps of:

(A) receiving by means of an apparatus input the AC power supply signal having a frequency and a peak value;

(B) low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input;

(C) rectifying an AC signal delivered from step (B) to produce a rectified voltage signal at an output of a rectifying means;

(D) providing an inductor connected in series to the output of the rectifying means;

(E) modulating a current flowing through the inductor to produce a modulated alternating current through the inductor at a frequency higher than the one of the AC power supply signal and to produce a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal by means of a modulating means including a controllable high frequency switch means connected to a rectifying element to form a boost converter, the controllable high frequency switch means having a gate for receiving a switch control signal;

(F) low pass filtering alternating voltage components out of the regulated voltage signal, and delivering the DC output voltage signal; and

(G) controlling the controllable high frequency switch means to produce a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal to regulate the DC output voltage signal at a desired voltage signal, the step (G) further including steps of;

(I) detecting the DC output voltage signal delivered from step (F) and delivering an output signal indicative of the DC output voltage signal;

(II) comparing the output signal delivered in step (I) to a reference voltage signal to produce a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

(III) producing the switch control signal by means of a pulse width modulator as a function of the signal produced from step (II).

26. Method of operating a separable two-part battery charger for supplying a direct current signal to battery connect terminals, comprising steps of:

(a) providing a first part which includes;

a secondary winding of an impedance matching transformer, having an output for delivering a transformed alternating current signal;

a first magnetic core part of the impedance matching transformer, which is magnetically coupled to the secondary winding;

a current rectifier for rectifying the transformed alternating current signal and delivering a rectified current signal; and

a low pass filter means for low pass filtering the rectified current signal to supply the direct current signal to the battery connect terminals;

(b) providing a second part which includes;

a power supply means for producing a DC output voltage signal;

an inverter resonant circuit means for inverting the DC output voltage signal and delivering an alternating current signal;

a primary winding of the impedance matching transformer, having an input for receiving the alternating current signal;

a second magnetic core part of the impedance matching transformer, which is magnetically coupled to the first primary winding, the second magnetic core part being mechanically connectable to the first magnetic core part;

(c) detecting a current flowing through the inverter resonant circuit means and delivering a current signal indicative of the current flowing through the inverter resonant circuit means;

(d) averaging the current signal delivered from step (c) and delivering an average current signal;

(e) comparing the average current signal to a current reference signal and delivering a signal indicative of a difference between the average current signal and the current reference signal, the difference being representative of quality of mechanical coupling between the first and second magnetic core parts; and

(f) indicating to a user the quality of mechanical coupling between the first and second magnetic core parts, the indicating of step (f) being based on the signal delivered from step (e).

27. A method according to claim 26, wherein:

in step (b), the power supply means is a voltage regulating means for producing the DC output voltage signal from an AC power supply signal and the inverter resonant circuit means comprises;

an inverter means for inverting the DC output voltage signal and delivering a square voltage signal, the inverter means including four controllable high frequency bidirectional switch elements connected in a bridge configuration having two opposite input ends for receiving the DC output voltage signal, and two other opposite output ends for supplying the square voltage signal, each of the four switch elements having a gate for receiving a switch control signal at a controlled frequency determining the direct current signal supplied to the battery connect terminals; and

a resonant circuit having an input for receiving the square voltage signal and an output for producing the alternating current signal;

the method further comprising steps of;

(g) detecting the DC output voltage signal and delivering an average voltage signal indicative of the DC output voltage signal;

(h) controlling the four switch elements by means of the following steps;

(i) multiplying the average voltage signal delivered in step (g) by the average current signal delivered in step (d) and delivering a battery power signal indicative of a power supplied to the battery connect terminals;

(ii) comparing the battery power signal to a reference power signal and delivering a value representative of a difference between the battery power signal and the reference power signal; and

(iii) delivering the switch control signals at the controlled frequency as a function of the value delivered in step (ii).

28. A method according to claim 27, further comprising steps of:

(j) providing a tertiary winding of the impedance matching transformer, which is magnetically coupled to the primary and secondary windings, the tertiary winding being for delivering a voltage signal indicative of a voltage at the battery connect terminals; and

wherein step (h) further comprises steps of;

(iv) detecting a peak voltage of the signal delivered by the tertiary winding and delivering a peak signal representative of the peak voltage of the signal delivered by the tertiary winding; and

(v) comparing the peak signal delivered in step (iv) to a predetermined threshold signal, and delivering an output signal when the peak signal reaches the threshold signal, the output signal delivered in step (v) preventing the delivering of step (iii).

29. A method according to claim 26, wherein, in step (b), the power supply means is a voltage regulating means performing the steps of:

(A) receiving by means of an apparatus input an AC power supply signal having a frequency and a peak value;

(B) low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input by means of a low pass filter having an input connected to the apparatus input, and an output;

(C) providing an inductor connected to the output of the low pass filter;

(D) modulating an alternating current flowing through the inductor at a frequency higher than the one of the AC power supply signal, and rectifying this alternating current to deliver a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal by means of a rectifying-modulating bridge circuit means, the bridge circuit means including two rectifying elements connected respectively to two controllable high frequency bidirectional switch elements to form a pair of boost converters, each of the switch elements having a gate for receiving a switch control signal;

(E) low pass filtering alternating voltage components out of the regulated voltage signal, and delivering the DC output voltage signal; and

(F) controlling the switch elements to produce a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal to regulate the DC output voltage signal at a desired voltage signal, the step (F) further including steps of;

(I) detecting the DC output voltage signal delivered from step (E), and delivering an output signal indicative of the DC output voltage signal;

(II) comparing the output signal delivered in step (I) to a reference voltage signal to produce a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

(III) producing the switch control signals by means of a pulse width modulator as a function of the signal produced from step (II).

30. A method according to claim 26, wherein:

the inverter resonant circuit means includes controllable high frequency bidirectional switch elements, each of the switch elements having a gate for receiving a switch control signal at a controlled frequency determining the direct current signal supplied to the battery connect terminals; and

the second part includes;

a tertiary winding of the impedance matching transformer, which is magnetically coupled to the second magnetic core part, the tertiary winding being for delivering a voltage signal indicative of a voltage at the battery connect terminals;

the method further includes a step of controlling the switch elements as a function of the voltage signal delivered by the tertiary winding.

31. A method according to claim 26, wherein, in step (b), the power supply means is a voltage regulating means performing the steps of:

(A) receiving by means of an apparatus input an AC power supply signal having a frequency and a peak value;

(B) low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input;

(C) rectifying an AC signal delivered from step (B) to produce a rectified voltage signal at an output of a rectifying means;

(D) providing an inductor connected in series to the output of the rectifying means;

(E) modulating a current flowing through the inductor to produce a modulated alternating current through the inductor at a frequency higher than the one of the AC power supply signal and to produce a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal by means of a modulating means including a controllable high frequency switch means connected to a rectifying element to form a boost converter, the controllable high frequency switch means having a gate for receiving a switch control signal;

(F) low pass filtering alternating voltage components out of the regulated voltage signal, and delivering the DC output voltage signal; and

(G) controlling the controllable high frequency switch means to produce a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal to regulate the DC output voltage signal at a desired voltage signal, the step (G) further including steps of;

(I) detecting the DC output voltage signal delivered from step (F) and delivering an output signal indicative of the DC output voltage signal;

(II) comparing the output signal delivered in step (I) to a reference voltage signal to produce a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

(III) producing the at least one control signal by means of a pulse width modulator as a function of the signal produced from step (II).

32. A separable two-part battery charger for supplying a direct current signal to battery connect terminals, comprising a first part and a second part, wherein:

the first part includes;

a secondary winding of an impedance matching transformer, having an output for delivering a transformed alternating current signal;

a first magnetic core part of the impedance matching transformer, which is magnetically coupled to the secondary winding;

a current rectifier for rectifying the transformed alternating current signal and delivering a rectified current signal; and

a low pass filter means for low pass filtering the rectified current signal to supply the direct current signal to the battery terminals; and

the second part includes;

a power supply means for producing a DC output voltage signal;

an inverter resonant circuit means for inverting the DC output voltage signal and delivering an alternating current signal, the inverter resonant circuit means including controllable high frequency bidirectional switch elements, each of the switch elements having a gate for receiving a switch control signal at a controlled frequency determining the direct current signal supplied to the battery connect terminals;

a primary winding of the impedance matching transformer, having an input for receiving the alternating current signal;

a second magnetic core part of the impedance matching transformer, which is magnetically coupled to the first primary winding, the second magnetic core part being mechanically connectable to the first magnetic core part;

a tertiary winding of the impedance matching transformer, which is magnetically coupled to the second magnetic core part, the tertiary winding being for delivering a voltage signal indicative of a voltage at the battery connect terminals; and

a controller for controlling the switch elements as a function of the voltage signal delivered by the tertiary winding.

33. A charger according to claim 32, wherein:

the current rectifier includes four diodes connected according to a diode bridge configuration having an output; and

the low pass filter means comprises a capacitor connected in parallel to the output of the diode bridge configuration, and an inductance connected in series to the battery connect terminals.

34. A charger according to claim 32, wherein:

the power supply means is a voltage regulating means for producing the DC output voltage signal from an AC power supply signal;

the inverter resonant circuit means comprises;

an inverter means for inverting the DC output voltage signal and delivering a square voltage signal, the inverter means including four controllable high frequency bidirectional switch elements connected in a bridge configuration having two opposite input ends for receiving the DC output voltage signal, and two other opposite output ends for supplying the square voltage signal, each of the four switch elements having a gate for receiving a switch control signal at a controlled frequency determining the direct current signal supplied to the battery connect terminals; and

a resonant circuit having an input for receiving the square voltage signal and an output for delivering an alternating current signal;

the charger further comprises;

a voltage detecting means for detecting the DC output voltage signal and delivering a voltage signal indicative of the DC output voltage signal; and

a current detector for detecting a current signal at the inputs ends of the bridge configuration and delivering a signal indicative of the current signal; and

the controller includes;

a current averaging means for averaging the signal delivered by the current detector and delivering an average current signal indicative of an average value of the current signal;

multiplying means for multiplying the voltage signal delivered by the voltage detecting means by the average current signal and delivering a battery power signal indicative of a power supplied to the battery connect terminals;

a regulating means for comparing the battery power signal to a reference power signal and delivering a value representative of a difference between the battery power signal and the reference power signal; and

an oscillator having an output for delivering the switch control signals at the controlled frequency as function of the value delivered by the regulating means.

35. A charger according to claim 34, wherein the voltage detecting means is a voltage divider having two resistors connected in series.

36. A charger according to claim 34, wherein the resonant circuit comprises a capacitor and an inductor connected in series.

37. A charger according to claim 34, wherein the controller comprises:

a frequency limiter having an input connected to the output of the oscillator, and an output for delivering the switch control signals at a frequency which is limited under a predetermined threshold value; and

a driver having an input connected to the output of the limiter, and outputs connected to the gates of the four controllable high frequency bidirectional switch elements.

38. An apparatus according to claim 34, wherein the controller comprises:

a peak voltage detector for detecting a peak voltage of the signal delivered by the tertiary winding and delivering a peak signal representative of the peak voltage of the signal delivered by the tertiary winding;

comparing means for comparing the peak signal delivered by the peak voltage detector to a predetermined threshold signal, and delivering an output signal when the peak signal reaches the threshold signal, the output signal of the comparing means preventing operation of the oscillator.

39. An apparatus according to claim 32, wherein the power supply means is a voltage regulating means comprising:

an apparatus input for receiving the AC power supply signal having a frequency and a peak value;

a first low pass filter having an input connected to the apparatus input for low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input, the low pass filter having also an output;

an inductor connected to the output of the low pass filter;

a rectifying-modulating bridge circuit means for modulating an alternating current flowing through the inductor at a frequency higher than the one of the AC power supply signal, rectifying this alternating current, and delivering a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal, the bridge circuit means including two rectifying elements connected respectively to two controllable high frequency bidirectional switch elements to form a pair of boost converters, each of the switch elements having a gate for receiving a switch control signal;

a second low pass filter for low pass filtering alternating voltage components out of the regulated voltage signal, the second low pass filter having an output for delivering the DC output voltage signal; and

voltage detecting means for detecting the DC output voltage signal, the voltage detecting means having an output for delivering an output signal indicative of a value of the DC output voltage signal; and

a controlling means for controlling the switch elements to regulate the DC output voltage signal at a desired voltage signal by producing a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal, the controlling means including;

a comparing means for comparing the output signal of the voltage detecting means to a reference voltage signal and delivering a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

a pulse width modulator for producing the switch control signals as a function of the signal delivered by the comparing means.

40. An apparatus according to claim 32, wherein the power supply means is a voltage regulating means comprising:

an apparatus input for receiving the AC power supply signal having a frequency and a peak value;

a first low pass filter for low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input;

rectifying means for rectifying an AC signal delivered from the first low pass filter, the rectifying means having an output for delivering a rectified voltage signal;

an inductor connected in series to the output of the rectifying means;

modulating means for modulating a current flowing through the inductor to produce a modulated alternating current through the inductor at a frequency higher than the one of the AC power supply signal and to produce a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal, the modulating means including a rectifying element connected to a controllable high frequency switch means to form a boost converter, the controllable high frequency switch means having a gate for receiving a switch control signal;

a second low pass filter for low pass filtering alternating voltage components out of the regulated voltage signal, and delivering the DC output voltage signal; and

a voltage detecting means for detecting the DC output voltage signal and delivering an output signal indicative of the DC output voltage signal;

controlling means for controlling the controllable high frequency switch means to regulate the DC output voltage signal at a desired voltage signal by producing a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal, the controlling means including;

a comparing means for comparing the output signal of the voltage detecting means to a reference voltage signal and delivering a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

a pulse width modulator for producing the at least one control signal as a function of the signal delivered by the comparing means.

41. Method of operating a separable two-part battery charger for supplying a direct current signal to battery connect terminals, comprising steps of:

(a) providing a first part which includes;

a secondary winding of an impedance matching transformer, having an output for delivering a transformed alternating current signal;

a first magnetic core part of the impedance matching transformer, which is magnetically coupled to the secondary winding;

a current rectifier for rectifying the transformed alternating current signal and delivering a rectified current signal; and

a low pass filter means for low pass filtering the rectified current signal to supply the direct current signal to the battery terminals;

(b) providing a second part which includes;

a power supply means for producing a DC output voltage signal;

an inverter resonant circuit means for inverting the DC output voltage signal and delivering an alternating current signal, the inverter resonant circuit means including controllable high frequency bidirectional switch elements, each of the switch elements having a gate for receiving a switch control signal at a controlled frequency determining the direct current signal supplied to the battery connect terminals;

a primary winding of the impedance matching transformer, having an input for receiving the alternating current signal;

a second magnetic core part of the impedance matching transformer, which is magnetically coupled to the first primary winding, the second magnetic core part being mechanically connectable to the first magnetic core part;

a tertiary winding of the impedance matching transformer, which is magnetically coupled to the second magnetic core part, the tertiary winding being for delivering a voltage signal indicative of a voltage at the battery connect terminals; and

(c) controlling the switch elements as a function of the voltage signal delivered by the tertiary winding.

42. A method according to claim 41, wherein step (c) further comprises steps of:

detecting a peak voltage of the signal delivered by the tertiary winding and delivering a peak signal representative of the peak voltage of the signal delivered by the tertiary winding; and

comparing the peak signal delivered by the peak voltage detector to a predetermined threshold signal, and delivering an output signal when the peak signal reaches the threshold signal, the output signal delivered in the comparing step preventing operation of the inverter resonant circuit means.

43. A method according to claim 41, wherein in step (b), the power supply means is a voltage regulating means for producing the DC output voltage signal from an AC power supply signal and performs steps of:

(A) receiving by means of an apparatus input the AC power supply signal having a frequency and a peak value;

(B) low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input by means of a first low pass filter means having an input connected to the apparatus input, and an output;

(C) providing an inductor connected to the output of the low pass filter means;

(D) modulating an alternating current flowing through the inductor at a frequency higher than the one of the AC power supply signal, and rectifying this alternating current to deliver a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal by means of a rectifying-modulating bridge circuit means, the bridge circuit means.. including two rectifying elements connected respectively to two controllable high frequency bidirectional switch elements to form a pair of boost converters, each of the switch elements having a gate for receiving a switch control signal;

(E) low pass filtering alternating voltage components out of the regulated voltage signal, and delivering the DC output voltage signal; and

(F) controlling the switch elements to produce a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal to regulate the DC output voltage signal at a desired voltage signal, the step (F) further including steps of;

(I) detecting the DC output voltage signal delivered from step (E), and delivering an output signal indicative of DC output voltage signal;

(II) comparing the output signal delivered in step (I) to a reference voltage signal to produce a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

(III) producing the switch control signals by means of a pulse width modulator as a function of the signal produced from step (II).

44. A method according to claim 41, wherein, in step (b), the power supply means is a voltage regulating means performing steps of:

(A) receiving by means of an apparatus input an AC power supply signal having a frequency and a peak value;

(B) low pass filtering high-frequency current components out of the AC power supply signal received at the apparatus input;

(C) rectifying an AC signal delivered from step (B) to produce a rectified voltage signal at an output of a rectifying means;

(D) providing an inductor connected in series to the output of the rectifying means;

(E) modulating a current flowing through the inductor to produce a modulated alternating current through the inductor at a frequency higher than the one of the AC power supply signal and to produce a regulated voltage signal having a value equal or greater than the peak value of the AC power supply signal by means of a modulating means including a controllable high frequency switch means connected to a rectifying element to form a boost converter, the controllable high frequency switch means having a gate for receiving a switch control signal;

(F) low pass filtering alternating voltage components out of the regulated voltage signal, and delivering the DC output voltage signal; and

(G) controlling the controllable high frequency switch means to produce a discontinuous current through the inductor at a frequency substantially higher than the frequency of the AC power supply signal to regulate the DC output voltage signal at a desired voltage signal, the step (G) further including steps of;

(I) detecting the DC output voltage signal delivered from step (F) and delivering an output signal indicative of the DC output voltage signal;

(II) comparing the output signal delivered in step (I) to a reference voltage signal to produce a signal representative of a difference between the DC output voltage signal and the desired voltage signal; and

(III) producing the at least one control signal by means of a pulse width modulator as a function of the signal produced from step (II).