Adaptive boost switching preregulator and method having variable output voltage responsive to input voltage

• US 5,406,192 A
• Filed: 08/11/1993
• Issued: 04/11/1995
• 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): Sterrett, Jeffrey L.
• Application Number:
  US08/107,441
• Time in Patent Office: 608 Days
• Field of Search: 323/222, 323/266, 323/281, 323/284, 323/299, 323/301, 323/906, 363/80, 363/81, 363/89, 363/143
• US Class Current: 323/222
• 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

A boost switching preregulator includes a boost switching power conversion device which converts power from a source of essentially DC unipolar input voltage for delivery as an essentially DC unipolar output voltage to a load. The preregulator also includes a control device which accepts an input indicative of the magnitude of the output voltage and which, in response to variations in the magnitude of the input voltage, controls the boost switching power conversion device such that the magnitude of the output voltage varies within a range. Within this range, the unipolar output voltage is greater than or equal to the magnitude of the unipolar input voltage, and the span of the range is at least ten percent of the maximum value of the unipolar output voltage.

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 controls said boost switching power conversion means such that when the magnitude of said unipolar input voltage is between a minimum value and a maximum value, said unipolar output voltage is varied within a range as a function of the magnitude of said unipolar input voltage, said unipolar output voltage being boosted to be greater than the magnitude of said unipolar input voltage, and the span of said range being at least ten percent of the maximum value of said unipolar output voltage.

2. 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 said unipolar input voltage, Vin, is less than Vin1;

(b) Vo=Vo2 if Vin is greater 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 Vo1 and Vin2;

Vo1 is greater than Vin1; and

Vin2 is greater than Vin1.

3. The preregulator of claim 2 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.

4. The preregulator of claim 2 wherein Vo1 is essentially 300 Volts, Vo2 is essentially 390 Volts, Vin1 is essentially 270 V and Vin2 is essentially 380 V.

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

6. The preregulator of claim 1 wherein said control means varies said unipolar output voltage between two values.

7. The preregulator of claim 1 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,

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,

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 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 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.

8. The preregulator of claim 7 wherein Vi1 is essentially 200 Volts, Vi2 is essentially 230 Volts, Vo1 is essentially 250 Volts, and Vo2 is essentially 385 Volts.

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

10. 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 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.

11. 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 when the magnitude of said unipolar input voltage is between a minimum value and a maximum value, said unipolar output voltage is varied as a function of the magnitude of said unipolar input voltage, said unipolar output voltage being boosted to be greater than the magnitude of said unipolar input voltage, and said range being at least ten percent of the maximum value of said unipolar output voltage.

12. The method of claim 11 wherein said range falls within a predetermined spread of operating load voltages associated with said load.

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 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 such that when the magnitude of said unipolar input voltage is between a minimum value and a maximum value, said unipolar output voltage is varied within a range as a function of the magnitude of said unipolar input voltage to cause said unipolar output voltage to be boosted to be greater than 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.

14. 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 is greater 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 Vo1 and Vin2;

Vo1 is greater than Vin1; and

Vin2 is greater than Vin1.

15. The controller of claim 14 wherein Vo1 is essentially 300 Volts, Vo2 is essentially 390 Volts, Vin1 is essentially 270 V and Vin2 is essentially 380 V.

16. 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 said unipolar input voltage is above a second input voltage value Vi2, Vi2 being less than Vo1,

said setting means sets 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.

17. The controller of claim 16, 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.

18. The controller of claim 16 wherein Vi1 is essentially 200 Volts, Vi2 is essentially 230 Volts, Vo1 is essentially 250 Volts, and Vo2 is essentially 385 Volts.

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

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

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

22. The controller of claim 13 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.