Phase current detector

• US 7,084,601 B2
• Filed: 09/25/2002
• Issued: 08/01/2006
• Est. Priority Date: 09/25/2001
• Status: Active Grant

• Current Assignee: Daikin Industries Ltd
• Original Assignee: Daikin Industries Ltd
• Inventors: Taniguchi, Tomoisa, Maeda, Toshiyuki
• Primary Examiner(s): IP, SHIK LUEN PAUL
• Application Number:
  US10/432,678
• Publication Number:
  US 20040056661A1
• Time in Patent Office: 1,406 Days
• Field of Search: 318800-828, 318/725, 318/728, 318/762, 318/799, 363/37, 363/40, 363/66, 363/98, 323/89, 323/282, 322/22, 322/27, 322/49, 308/64, 361/22, 361/72
• US Class Current: 318/806
• CPC Class Codes: G01R 1/203 Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts resistors in general H01C; microwave or radiowave terminations H01P1/26; coupling devices H01R
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output
• CPC Class Codes: H02M 1/123 Suppression of common mode voltage or current
• CPC Class Codes: H02M 7/53875 with analogue control of three-phase output

Abstract

A first condenser is connected between output terminals of a rectifier circuit which receives an AC power as an input, and a three phase inverter is connected in parallel with respect to the first condenser, and output of the three phase inverter is supplied to a motor, and a second condenser is connected in parallel to the input side of the three phase inverter, and a current detector is connected between the first condenser and the second condenser, and a third condenser is connected in parallel to the first condenser at a position slightly power side with respect to the current detector, and the capacitance of the second condenser is determined as small as possible within the range in which power devices are not destroyed by surge voltage due to switching, therefore, ringing is suppressed, and taking of current is performed rapidly and with high accuracy.

Claims

1. A phase current detection apparatus that detects a phase current of a motor based upon a current of a DC link and a vector pattern applied to the motor, the motor being provided in a motor driving apparatus which supplies outputs from a PWM inverter to the motor to drive the motor, comprising:

a bypass condenser connected to an input side of the PWM inverter, the bypass condenser being in parallel with a first condenser of the motor driving apparatus, the bypass condenser also being further downstream from a rectifier of the motor driving apparatus relative to the first condenser;

a third condenser connected in between the first and bypass condensers and in parallel with both the first and bypass condensers; and

a current detector on the DC link of the motor driving apparatus in series between the third condenser and the bypass condenser; and

a low-pass filter connected to and parallel with the current detector,

wherein a cut-off frequency of the lowpass filter is set to a frequency to substantially suppress a component of a ringing frequency of the motor driving apparatus,

wherein the component of the ringing frequency is generated based upon wiring from the bypass condenser to power devices, wiring from the power devices to the motor, and within the motor.

2. The phase current detection apparatus as set forth in claim 1, wherein the low-pass filter includes changeover means for changing over cut-off frequencies.

3. A phase current detection apparatus that detects a phase current of a motor based upon a current of a DC link and a vector pattern applied to the motor, the motor being provided in a motor driving apparatus which supplies outputs from a PWM inverter to the motor to drive the motor, comprising:

a bypass condenser connected to an input side of the PWM inverter, the bypass condenser being in parallel with a first condenser of the motor driving apparatus, the bypass condenser also being further downstream from a rectifier of the motor driving apparatus relative to the first condenser;

a third condenser connected in between the first and bypass condensers and in parallel with both the first and bypass condensers;

a current detector on the DC link of the motor driving apparatus in series between the third condenser and the bypass condenser; and

a filter connected to and parallel with the current detector,

wherein the filter has a response speed which enables detection of a current at a predetermined minimum voltage vector length, and

wherein a line length from the inverter to the motor is matched by the filter so as to have a frequency which is equal to or more than a frequency to suppress ringing generated based upon wiring from the bypass condenser to power devices, wiring from the power devices to the motor, and within the motor.

4. The phase current detection apparatus as set forth in claim 3, wherein the filter includes a lowpass filter which utilizes a through-rate of an amplifier.

5. The phase current detection apparatus as set forth in claim 4, wherein the amplifier has a through-rate which is equal to or less than a value obtained by multiplying a ringing frequency and a maximum output voltage.

6. The phase current detection apparatus as set forth in claim 4, wherein the amplifier includes an operational amplifier having a bandwidth corresponding to a feedback capacitance.

7. A phase current detection apparatus that detects a phase current of a motor based upon a current of a DC link and a vector pattern applied to the motor, the motor being provided in a motor driving apparatus which supplies outputs from a PWM inverter to the motor to drive the motor, comprising:

a bypass condenser connected to an input side of the PWM inverter, the bypass condenser being in parallel with a first condenser of the motor driving apparatus, the bypass condenser also being further downstream from a rectifier of the motor driving apparatus relative to the first condenser;

a third condenser connected in between the first and bypass condensers and in parallel with both the first and bypass condensers;

a current detector on the DC link of the motor driving apparatus in series between the third condenser and the bypass condenser; and

a filter having a LC serial resonance circuit connected in parallel with the current detector,

wherein the LC serial resonance circuit is configured to have its resonance frequency matched to a frequency of ringing generated based upon wiring from the bypass condenser to power devices, wiring from the power devices to the motor, and within the motor.

8. A phase current detection apparatus that detects a phase current of a motor based upon a current of a DC link and a vector pattern applied to the motor, the motor being provided in a motor driving apparatus which supplies outputs from a PWM inverter to the motor to drive the motor, comprising:

a bypass condenser connected to an input side of the PWM inverter, the bypass condenser being in parallel with a first condenser of the motor driving apparatus, the bypass condenser also being further downstream from a rectifier of the motor driving apparatus relative to the first condenser;

a third condenser connected in between the first and bypass condensers and in parallel with both the first and bypass condensers;

a current detector on the DC link of the motor driving apparatus in series between the third condenser and the bypass condenser; and

a determination device for measuring at least one of a rising delay time, a descending delay time, and a waveform of a current corresponding to a command for the inverter, and for determining at least one of a current detection timing and a minimum voltage vector length based upon the measurement result.

9. The phase current detection apparatus as set forth in claim 8, wherein the determination device measures at least one of the rising delay time, the descending delay time, and the waveform of the current corresponding to a command for the inverter and flowing in the DC link under a condition in which DC current is flowing into the motor.

10. The phase current detection apparatus as set forth in claim 8,

wherein the motor driving apparatus is configured to carry out PWM wave generation using a triangle wave comparison method such that two voltage vectors from the inverter in synch with each other are output within one carrier that allows two related current wave forms to be observed, and

wherein the determination device carries out measurement of at least one of the rising delay time, the descending delay time, and the waveform of the current corresponding to a command for the inverter and measurement of the current for phase current detection, at a rising slope and descending slope of the triangle wave, respectively.

11. The phase current detection apparatus as set forth in claim 8, wherein the determination device reduces the current measurement for the phase current detection, and carries out measurement of at least one of the rising delay time, the descending delay time, and the waveform of a current corresponding to a command for the inverter.

12. The phase current detection apparatus as set forth in claim 11, wherein the motor drives an enclosed compressor.

13. A phase current detection apparatus that detects a phase current of a motor based upon a current of a DC link and a vector pattern applied to the motor, the motor being provided in a motor driving apparatus which supplies outputs from a PWM inverter to the motor to drive the motor, comprising:

a bypass condenser connected to an input side of the PWM inverter, the bypass condenser being in parallel with a first condenser of the motor driving apparatus, the bypass condenser also being further downstream from a rectifier of the motor driving apparatus relative to the first condenser;

a third condenser connected in between the first and bypass condensers and in parallel with both the first and bypass condensers; and

a current detector on the DC link of the motor driving apparatus in series between the third condenser and the bypass condenser; and

a first filter in parallel with the current detector, the filter provided for offsetting an error due to an inductance component accompanying a shunt resistor of the current detector.

14. The phase current detection apparatus as set forth in claim 13, wherein the first filter has a pole at a lower frequency than an upper limit of frequency characteristics required for the current detection circuit.

15. The phase current detection apparatus as set forth in claim 13, wherein the first filter involves a pole at a frequency generated by the shunt resistor and inductance component accompanying the shunt resistor.

16. The phase current detection apparatus as set forth in claim 13, further comprising a second filter which cancels an oscillation component of the current flowing in the shunt resistor.

17. The phase current detection apparatus as set forth in claim 16, wherein the first or second filter comprises passive elements and is connected directly to the shunt resistor.

18. A phase current detection apparatus that detects a phase current of a motor based upon a current of a DC link and a vector pattern applied to the motor, the motor being provided in a motor driving apparatus which supplies outputs from a PWM inverter to the motor to drive the motor, comprising:

a bypass condenser connected to an input side of the PWM inverter, the bypass condenser being in parallel with a first condenser of the motor driving apparatus, the bypass condenser also being further downstream from a rectifier of the motor driving apparatus relative to the first condenser;

a third condenser connected in between the first and bypass condensers and in parallel with both the first and bypass condensers; and

a current detector on the DC link of the motor driving apparatus in series between the third condenser and the bypass condenser; and

a noise canceling device provided to cancel noise due to magnetic flux generated from a shunt resistor of the current detector and the DC link.

19. A phase current detection apparatus that detects a phase current of a motor based upon a current of a DC link and a vector pattern applied to the motor, the motor being provided in a motor driving apparatus which supplies outputs from a PWM inverter to the motor to drive the motor, comprising:

a bypass condenser connected to an input side of the PWM inverter, the bypass condenser being in parallel with a first condenser of the motor driving apparatus, the bypass condenser also being further downstream from a rectifier of the motor driving apparatus relative to the first condenser;

a third condenser connected in between the first and bypass condensers and in parallel with both the first and bypass condensers; and

a current detector on the DC link of the motor driving apparatus in series between the third condenser and the bypass condenser,

wherein circuitry elements of the current detector implemented so that the circuitry elements are not affected by noise due to magnetic flux generated from a shunt resistor of the current detector and the DC link.

20. The phase current detection apparatus as set forth in claim 19, wherein the circuitry elements are implemented in parallel to a plane which is generated by magnetic flux generated from the shunt resistor and the DC link.

21. A motor driving apparatus, comprising:

a rectifier configured to convert an AC input power to a DC power and output the DC power via output terminals;

an inverter whose input terminals are connected to the output terminals of the rectifier, the inverter configured to receive the DC power from the rectifier and output a three-phase power;

first, second, and third condensers all connected in parallel between the output terminals of the rectifier, wherein the first condenser is electrically closest to the rectifier, the second condenser is electrically closest to the inverter, and the third condenser is electrically in between the first and second condensers; and

a current detector serially placed in a DC link of the motor driving apparatus between the second and third condensers,

wherein capacitances of the second and third condensers are set such that a resonance current is substantially equal to or less than a minimum detectable current, wherein the resonance current is current due to inductance of wirings between the first and third condensers, motor phase currents, and the second and third condensers.

22. A motor driving apparatus, comprising:

a rectifier configured to convert an AC input power to a DC power and output the DC power via output terminals;

an inverter whose input terminals are connected to the output terminals of the rectifier, the inverter configured to receive the DC power from the rectifier and output a three-phase power;

first, second, and third condensers all connected in parallel between the output terminals of the rectifier, wherein the first condenser is electrically closest to the rectifier, the second condenser is electrically closest to the inverter, and the third condenser is electrically in between the first and second condensers; and

a current detector serially placed in a DC link of the motor driving apparatus between the second and third condensers,

wherein the current detector comprises a filter and a shunt resistor connected in parallel, wherein a frequency characteristic of the filter is set to match a cutoff frequency of the motor driving apparatus.

23. The apparatus of claim 22, wherein the filter of the current detector comprises:

a capacitor with a first terminal connected to a ground and a second terminal connected to an output of the filter; and

a resistor with a first terminal connected to an input of the filter and a second terminal connected to the output of the filter,

wherein a capacitance of the capacitor is C and a resistance of the resistor is R, and

wherein a value RC is set such that a resonance frequency of the filter is substantially equal to or greater than a ringing frequency of the motor driving apparatus.

24. The apparatus of claim 22, wherein the current detector further comprises a current outputting section whose output serves as the output of the current detector, the current outputting section comprising:

an operational amplifier with a non-inversion input connected to the output of the filter and an output connected to the output of the current outputting section;

a first resistor with a first terminal connected to a ground and a second terminal connected to an inversion input of the operational amplifier;

a second resistor with a first terminal connected to the inversion input of the operational amplifier and a second terminal connected to the output of the operational amplifier; and

a capacitor with a first terminal connected to the inversion input of the operational amplifier and a second terminal connected to the output of the operational amplifier.

25. The apparatus of claim 22, further comprising an LC serial resonance circuit connected in parallel with the shunt resistor of the current detector.

26. The apparatus of claim 22, wherein a resonance frequency of the LC serial resonance circuit is substantially matched to a ringing frequency generated by wirings of the motor driving apparatus.

27. The apparatus of claim 26, wherein the wirings of the motor driving apparatus include wirings from the third condenser to power devices, from the power devices to a motor, and within the motor.

28. The apparatus of claim 22, wherein the filter of the current detector comprises a resistor and a capacitor connected in series, wherein a resistance Rc of the resistor and a capacitance Cc of the capacitor are set such that CcRc is substantially equal to Ls/Rs, wherein Rs is a resistance of the shunt resistor and Ls is a parasitic capacitance of the shunt resistor.

29. The apparatus of claim 22, wherein the current detector further comprises an amplifier circuit connected in parallel with the shunt resistor, wherein the amplifier circuit is oriented in parallel with a flux generated by current in the shunt resistor.