High-efficiency switching power converter

• US 5,734,564 A
• Filed: 07/26/1996
• Issued: 03/31/1998
• Est. Priority Date: 07/26/1996
• Status: Expired due to Fees

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Brkovic, Milivoje Slobodan
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US08/688,746
• Time in Patent Office: 613 Days
• Field of Search: 363/16, 363/18, 363/19, 363/20, 363/21, 363/97, 363/131, 323/299, 323/301, 323/303
• US Class Current: 363/21.16
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

For use with a power supply having a controllable switch that switches in response to a drive signal received from a drive signal generator, a circuit for, and method of, modifying the drive signal to cause the switch to turn on at a reduced voltage. The circuit includes: (1) a synchronization signal generating circuit that senses an electrical characteristic of the supply representing a voltage across the switch, the synchronization signal generating circuit developing a synchronization signal as a function of the characteristic and (2) a drive signal modifier circuit that receives the synchronization signal and causes the drive signal generator to modify the drive signal in response thereto, the synchronization signal generating circuit and drive signal generator cooperating to synchronize the drive signal to the characteristic thereby to reduce power dissipation in the switch.

Claims

1. For use with a power supply having a controllable switch that switches in response to a drive signal received from a drive signal generator, a circuit for modifying said drive signal to cause said switch to turn on at a reduced voltage, comprising:

a synchronization signal generating circuit that senses an electrical characteristic of said supply representing a voltage across said switch, said synchronization signal generating circuit developing a synchronization signal as a function of said characteristic; and

a drive signal modifier circuit that receives said synchronization signal and causes said drive signal generator to modify said drive signal in response thereto, said synchronization signal generating circuit and drive signal generator cooperating to synchronize said drive signal to said characteristic thereby to reduce power dissipation in said switch.

2. The circuit as recited in claim 1 wherein said switch is a field effect transistor (FET).

3. The circuit as recited in claim 1 wherein said drive signal is a pulse width modulated signal.

4. The circuit as recited in claim 1 wherein said characteristic oscillates, said synchronization signal generating circuit generating pulses upon sensing a maximum value of said characteristic.

5. The circuit as recited in claim 1 wherein said synchronization signal comprises a plurality of pulses, said drive signal modifier circuit causing said drive signal generator to superpose said pulses on an intermediate waveform developed within said drive signal generator and employed by said drive signal generator to develop said drive signal, said pulses thereby temporally advancing said drive signal.

6. The circuit as recited in claim 1 wherein said supply comprises a transformer having a bias winding coupled to said synchronization signal generating circuit, said synchronization signal generating circuit sensing said characteristic from said bias winding.

7. The circuit as recited in claim 1 wherein said synchronization signal generating circuit comprises a zener diode for limiting a voltage of pulses in said synchronization signal.

8. For use with a power supply having a controllable switch that switches in response to a drive signal received from a drive signal generator, a method of modifying said drive signal to cause said switch to turn on at a reduced voltage, comprising the steps of:

sensing an electrical characteristic of said supply representing a voltage across said switch;

developing a synchronization signal as a function of said characteristic; and

causing said drive signal generator to modify said drive signal in response thereto to synchronize said drive signal to said characteristic thereby to reduce power dissipation in said switch.

9. The method as recited in claim 8 wherein said switch is a field effect transistor (FET).

10. The method as recited in claim 8 wherein said drive signal is a pulse width modulated signal.

11. The method as recited in claim 8 wherein said characteristic oscillates, said step of developing comprising the step of generating pulses upon sensing a maximum value of said characteristic.

12. The method as recited in claim 8 wherein said synchronization signal comprises a plurality of pulses, said step of causing comprising the step of superposing said pulses on an intermediate waveform developed within said drive signal generator and employed by said drive signal generator to develop said drive signal, said pulses thereby temporally advancing said drive signal.

13. The method as recited in claim 8 wherein said supply comprises a transformer having a bias winding coupled to said synchronization signal generating circuit, said step of sensing comprising the step of sensing said characteristic from said bias winding.

14. The method as recited in claim 8 wherein said synchronization signal generating circuit comprises a zener diode, said step of developing comprising the step of limiting a voltage of pulses in said synchronization signal.

15. A power supply, comprising:

a controllable switch that switches in response to a pulse width modulated drive signal;

a drive signal generator, coupled to said switch, for generating said drive signal; and

a circuit for modifying said drive signal to cause said switch to turn on at a reduced voltage, including;

a synchronization signal generating circuit that senses an electrical characteristic of said supply representing a voltage across said switch, said synchronization signal generating circuit developing a synchronization signal as a function of said characteristic, and

a drive signal modifier circuit that receives said synchronization signal and causes said drive signal generator to modify said drive signal in response thereto, said synchronization signal generating circuit and drive signal generator cooperating to synchronize said drive signal to said characteristic thereby to reduce power dissipation in said switch.

16. The supply as recited in claim 15 wherein said switch is a field effect transistor (FET).

17. The supply as recited in claim 15 wherein said characteristic oscillates, said synchronization signal generating circuit generating pulses upon sensing a maximum value of said characteristic.

18. The supply as recited in claim 15 wherein said synchronization signal comprises a plurality of pulses, said drive signal modifier circuit causing said drive signal generator to superpose said pulses on an intermediate waveform developed within said drive signal generator and employed by said drive signal generator to develop said drive signal, said pulses thereby temporally advancing said drive signal.

19. The supply as recited in claim 15 wherein said supply comprises a transformer having a bias winding coupled to said synchronization signal generating circuit, said synchronization signal generating circuit sensing said characteristic from said bias winding.

20. The supply as recited in claim 15 wherein said synchronization signal generating circuit comprises a zener diode for limiting a voltage of pulses in said synchronization signal.

21. The supply as recited in claim 15 wherein said supply is selected from the group consisting of:

an AC to DC converter,

a DC to AC converter, and

a power factor-correcting circuit.