Adaptive boost switching preregulator and method

• US 5,289,361 A
• Filed: 01/16/1991
• Issued: 02/22/1994
• Est. Priority Date: 01/16/1991
• Status: Expired due to Term

• Current Assignee: VLT Incorporated (Vicor Corporation)
• Original Assignee: VLT Incorporated (Vicor Corporation)
• Inventors: Vinciarelli, Patrizio
• Primary Examiner(s): BEHA JR, WILLIAM
• Application Number:
  US07/642,232
• Time in Patent Office: 1,133 Days
• Field of Search: 323/222, 323/266, 323/281, 323/284, 323/299, 323/301, 363/80, 363/81, 363/89, 363/143
• US Class Current: 363/80
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• 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

Abstract

The performance of AC to DC and DC to DC boost preregulators, and the performance of the equipment of which they form a part, can be improved by means of an adaptive boost switching preregulator which can, when used with a load capable of operating over a range of load voltages, increase or optimize the conversion efficiency and reliability of both the preregulator and the load by adaptively controlling the load voltage as a function of the voltage of the input source. Also, a gain-variable current controller can be provided which allows for accurately controlling the waveform and magnitude of the input current of a switching preregulator as the preregulator load (and hence the input current) varies over a wide dynamic range, yet does so by comparing signals whose magnitudes are essentially independent of the magnitude of the load. In this way, second order effects, which cause degradation in control of power factor in other preregulators as load is decreased, are rendered less significant.

Claims

1. A boost switching preregulator comprising

boost switching power conversion means for converting power from a source of unipolar input voltage for delivery as a unipolar output voltage to a load, and

control means which accepts an input indicative of the magnitude of said unipolar output voltage and which, in response to variations in the magnitude of said unipolar input voltage, controls said boost switching power conversion means such that the magnitude of said unipolar output voltage varies within a range such that (a) said unipolar output voltage is greater than or equal to the magnitude of said unipolar input voltage, and (b) the span of said range is at least ten percent of the maximum value of said unipolar output voltage;

wherein said unipolar input voltage is a time-varying unipolar voltage derived from an AC source and having a peak value Vp, and said control means varies the value of said unipolar output voltage Vo within said range such that Vo is greater than or equal to Vp.

2. The preregulator of claim 1 wherein said range falls within a predetermined spread of operating load voltages associated with said load.

3. The preregulator of claim 1 wherein said control means causes said unipolar output voltage to increase (decrease) as said unipolar input voltage increases (decreases).

4. The preregulator of claim 1 wherein said controller varies said unipolar output voltage between two values.

5. The preregulator of claim 1 wherein

said control means sets the value of said unipolar output voltage either to a first load voltage value, Vo1, or a second load voltage value, Vo2, said first load voltage value being less than said second load voltage value,

said control means sets said unipolar output voltage output voltage equal to said second load voltage value, Vo2, if the peak value of said unipolar input voltage is above a second input voltage value Vi2, Vi2 being less than Vo1,

said control means sets said unipolar output voltage equal to said first load voltage, Vo1, if the peak value of said unipolar input voltage is below a first input voltage value, Vi1, Vi1 being less than both Vi2 and Vo1, and

said control means maintains said unipolar output voltage at said first load voltage value, Vo1, if the peak value of said unipolar input voltage increases above said first input voltage value, Vi1, but does not exceed said second input voltage value, Vi2, and maintains said unipolar output voltage at said second load voltage value, Vo2, if the peak value of said unipolar input voltage decreases below said second input voltage value, Vi2, but does not become less than said first input voltage value, Vi1.

6. The preregulator of claim 1 wherein said control means sets said unipolar output voltage, Vo, in accordance with the following predefined relationship:

(a) Vo=Vo1 if the peak value of said unipolar input voltage, Vin, is less than VinI;

(b) Vo =Vo2 if the peak value of said unipolar input voltage, Vin, is greater than Vin2 and less than or equal to Vo2;

(c) For peak values of said unipolar input voltage, Vin, between VinI and Vin2, Vo varies linearly between the values Vol and Vo2;

where Vin is the peak value of said unipolar input voltage;

Vo2 is greater than both Vol and Vin2;

Vo1 is greater than Vin1; and

Vin2 is greater than Vin1.

7. The preregulator of claim 6 wherein the operating load voltage range is between Vlmin and Vlmax, Vlmin and Vlmax being, respectively, the minimum and maximum values of the operating voltage range of said load, Vo1 being greater than Vlmin, and Vo2 being less than Vlmax.

8. The preregulator of claim 6 wherein Vo1 is essentially 300 Volts, Vo2 is essentially 390 Volts, Vinl is essentially 270V and Vin2 is essentially 380V.

9. The preregulator of claim 1 wherein said control means includes an adaptive reference source, said adaptive reference source accepting an input signal indicative of the peak value of said unipolar input voltage, said adaptive reference source delivering a reference signal, Vra, indicative of the value at which said control means is to maintain the average value of said unipolar output voltage, said adaptive reference source varying the magnitude of the reference signal, Vra, as a means of adjusting the average value of said unipolar output voltage over said predefined range.

10. A boost switching prereglator comprising

boost switching power conversion means for converting power from a source of unipolar input voltage for delivery as a unipolar output voltage to a load, and

control means which accepts an input indicative of the magnitude of said unipolar output voltage and which, in response of variations in the magnitude of said unipolar input voltage, controls said boost switching power conversion means such that the magnitude of said unipolar output voltage varies within a range such that (a) said unipolar output voltage is greater than or equal to the magnitude of said unipolar input voltage, and (b) the span of said range is at least ten percent of the maximum value of said unipolar output voltage;

wherein said control means is arranged to set the value of said unipolar output voltage either to a first load voltage value, Vo1, or a second load voltage value, Vo2, said first load voltage value being less than said second load voltage value,

wherein said control means sets said unipolar output voltage equal to said second load voltage value, Vo2, if said unipolar input voltage is above a second input voltage value Vi2, Vi2 being less than Vo1,

wherein said control means sets said unipolar output voltage equal to said first load voltage, Vo1, if said unipolar input voltage is below a first input voltage vale, Vi1, Vi1 being less than both Vi2 and Vo1, and

wherein said control means maintains said unipolar output voltage at said first load voltage value, Vo1, if said unipolar input voltage increases above said first input voltage value, Vi1, but does not exceed said second input voltage value, Vi2, and maintains said unipolar output voltage at said second load voltage value, Vo2, if said input voltage decreases below said second input voltage value, Vi2, but does not become less than said first input voltage value, Vi1.

11. The preregulator of claim 10 or 5 wherein Vi1 is essentially 200 Volts, Vi2 is essentially 230 Volts, Vo1 is essentially 250 Volts, and Vo2 is essentially 385 Volts.

12. A boost switching preregulator comprising

boost switching power conversion means for converting power from a source of unipolar input voltage for delivery as a unipolar output voltage to a load, and

control means which accepts an input indicative of the magnitude of said unipolar output voltage and which, in response to variations in the magnitude of said unipolar input voltage, controls said boosts witching power conversion means such that the magnitude of said unipolar output voltage varies within a range such that (a) said unipolar output voltage is greater than or equal to the magnitude of said unipolar input voltage, and (b) the span of said range is at least ten percent of the maximum value of said unipolar output voltage;

wherein said control means includes an adaptive reference source, said adaptive reference source accepting an input signal indicative of the magnitude of said unipolar input voltage, said adaptive reference source delivering a reference signal, Vra, indicative of the value at which said control means is to maintain said unipolar output voltage, said adaptive reference source varying the magnitude of the reference signal, Vra, as a means of adjusting the value of said unipolar output voltage over said range.

13. A controller for use in a boost switching preregulator of the kind having a boost switching power converter which converts power from a source of unipolar input voltage for delivery as a unipolar output voltage to a load, said controller comprising

input means for receiving an input signal indicative of the magnitude of said unipolar input voltage,

output means of outputting a control signal to said boost switching power converter to control said unipolar output voltage, and

control means for varying said control signal in response to said input signal to cause said unipolar output voltage to be greater than or equal to the magnitude of said unipolar input voltage, and to cause said unipolar output voltage to vary within a range spanning at least ten percent of the maximum value of said unipolar output voltage;

wherein said unipolar input voltage is a time-varying unipolar voltage derived from an AC source and having a peak value Vp, and

said controller includes means for varying the value of said unipolar output voltage voltage Vo within said range such that Vo is greater than or equal to Vp.

14. The controller of claim 13 wherein

said unipolar input voltage is an essentially DC voltage at level Vin, and

said unipolar output voltage is an essentially DC voltage at level Vo.

15. The controller of claim 13 wherein said range falls within a predetermined spread of operating load voltages associated with said load.

16. The controller of claim 13 further comprising means for causing said unipolar output voltage to increase (decrease) as said unipolar input voltage increases (decreases).

17. The controller of claim 13 further comprising means for varying said unipolar output voltage between two values.

18. The controller of claim 13 further comprising setting means for setting the value of said unipolar output voltage either to a first load voltage value, Vo1, or a second load voltage value, Vo2, said first load voltage value being less than said second load voltage value, and wherein

said setting means

sets said unipolar output voltage equal to said second load voltage value, Vo2, if the peak value of said unipolar input voltage is above a second input voltage value Vi2, Vi2 being less than Vo1,

sets said unipolar output voltage equal to said first load voltage, Vol, if the peak value of said unipolar input voltage is below a first input voltage value, Vi1, Vi1 being less than both Vi2 and Vo1,

maintains said unipolar output voltage at said first load voltage value, Vol, if the peak value of said unipolar input voltage increases above said first input voltage value, Vi1, but does not exceed said second input voltage value, Vi2, and

maintains said unipolar output voltage at said second load voltage value, Vo2, if the peak value of said unipolar input voltage decreases below said second input voltage value, Vi2, but does not become less than said first input voltage value, Vi1.

19. The controller of claim 13 further comprising setting means for setting said unipolar output voltage, Vo, in accordance with the following predefined relationship:

(a) Vo =Vo1 if said unipolar input voltage, Vin, is less than Vin1;

(b) Vo=Vo2 if Vin i than Vin2 and less than or equal to Vo2;

(c) for values of Vin between Vin1 and Vin2, Vo varies linearly between the values Vo1 and Vo2;

where Vin is the value of said unipolar input voltage;

Vo2 is greater than both Vol and Vin2;

Vol is greater than Vin1; and

Vin2 is greater than Vin1.

20. The controller of claim 13 further comprising setting means for said unipolar output voltage, Vo, in accordance with the following predefined relationship:

(a) Vo=Vol if the peak value of said unipolar input voltage, Vin, is less than Vin1;

(b) Vo=Vo2 if the peak value of said unipolar input voltage, Vin, is greater than Vin2 and less than or equal to Vo2;

(c) for peak values of said unipolar input voltage, Vin, Vin1 and Vin2, Vo varies linearly between the values Vo1 and Vo2;

where Vin is the peak value of said unipolar input voltage;

Vo2 is greater than both Vol and Vin2;

Vo1 is greater than Vin1; and

Vin2 is greater than Vin1.

21. The controller of claim 19 or 20 wherein Vo1 is essentially 300 Volts, Vo2 is essentially 390 Volts, Vin1 is essentially 270V and Vin2 is essential 380V.

22. The controller of claim 13 further comprising an adaptive reference source, said adaptive reference source accepting an input signal indicative of the peak value of said unipolar input voltage, said adaptive reference source delivering a reference signal, Vra, indicative of the value at which said controller is to maintain said average unipolar output voltage, said adaptive reference source varying the magnitude of the reference signal, Vra, as a means of adjusting the average value of said unipolar output voltage over said range.

23. A controller for use in a boost switching preregulator of the kind having a boost switching power converter which converts power from a source of unipolar input voltage for delivery as a unipolar output voltage to a load, said controller comprising

input means for receiving an input signal indicative of the magnitude of said unipolar input voltage,

output means for outputting a control signal to said boost switching power converter to control said unipolar output voltage, and

control means for varying said control signal in response to said input signal to cause said unipolar output voltage to be greater than or equal to the magnitude of said unipolar input voltage, and to cause said unipolar output voltage to vary within a range spanning at least ten percent of the maximum value of said unipolar output voltage;

further comprising setting means for setting the value of said unipolar output voltage either to a first load voltage value, Vo1, or a second load voltage value, Vo2, said first load voltage value being less than said second load voltage value, and wherein

said setting means sets said unipolar output voltage equal to said second load voltage value, Vo2, if said unipolar input voltage is above a second input voltage value, Vi2, Vi2 being less than Vo1,

said setting mans ses said unipolar output voltage equal to said first load voltage, Vo1, if said unipolar input voltage is below a first input voltage value, Vi1, Vi1 being less than both Vi2 and Vo1, and

said setting means maintains said unipolar output voltage at said first load voltage value, Vo1, if said unipolar input voltage increases above said first input voltage value, Vi1, but does not exceed said second input voltage value, Vi2, and maintains said unipolar output voltage at said second load voltage value, Vo2, if said input voltage decreases below said second input voltage value, Vi2, but does not become less than said first input voltage value, Vi1.

24. The controller of claim 23 or 18 wherein Vi1 is essentially 200 Volts, Vi2 is essentially 230 volts, Vo1 is essentially 250 Volts, and Vo2 is essentially 385 Volts.

25. The controller of claim 23, 18, 19, or 20 wherein the operating load voltage range is between Vlmin and Vlmax, Vlmin and Vlmax being, respectively, the minimum and maximum values of the operating voltage range of said load, Vo1 being greater than Vlmin, and Vo2 being less than Vlmax.

26. A controller for use in a boost switching preregulator of the kind having a boost switching power converter which converts power from a source of unipolar input voltage for delivery as a unipolar output voltage to a load, said controller comprising

input means for receiving an input signal indicative of the magnitude of said unipolar input voltage,

output means for outputting a control signal to said boost switching power converter to control said unipolar output voltage, and

control means for varying said control signal in response to said input signal to cause said unipolar output voltage to be greater than or equal to the magnitude of said unipolar input voltage, and to cause said unipolar output voltage to vary within a range spanning at least ten percent of the maximum value of said unipolar output voltage;

further comprising an adaptive reference source, said adaptive reference source accepting an input signal indicative of the magnitude of said unipolar input voltage, said adaptive reference source delivering a reference signal, Vra, indicative of the value at which said controller is to maintain said unipolar output voltage, said adaptive reference source varying the magnitude of the reference signal, Vra, as a means of adjusting the value of said unipolar output voltage over said range.

27. A method of controlling a boost switching preregulator of the kind which converts power from a source of unipolar input voltage for delivery as a unipolar output voltage to a load, said method comprising the steps of

varying the value of said unipolar output voltage in response to variations in the magnitude of said unipolar input voltage within a range such that said unipolar output voltage is greater than or equal to the magnitude of said unipolar input voltage, and

varying the value of said unipolar output voltage in response to variations in the magnitude of said unipolar input voltage within a range that spans at least ten percent of the maximum value of said unipolar output voltage;

wherein said unipolar input voltage is a time-varying unipolar voltage derived from an AC source and having a peak value Vp, and the value of said unipolar output voltage Vo is varied within a range such that Vo is greater than or equal to Vp.

28. The method of claim 21 wherein

said unipolar input voltage is an essentially DC voltage at level Vin, and

said unipolar output voltage is an essentially DC voltage at level Vo.

29. The method of claim 27 wherein said range falls within a predetermined spread of operating load voltages associated with said load.