POWER SUPPLY WITH SINGLE STAGE CONVERTER FOR PERFORMING POWER FACTOR CORRECTION AND RESONANT CONVERSION

• US 20120106206A1
• Filed: 01/31/2011
• Published: 05/03/2012
• Est. Priority Date: 10/27/2010
• Status: Active Grant

• Current Assignee: Delta Electronics Incorporated
• Original Assignee: Delta Electronics Incorporated
• Inventors: Tang, Pak-Chuen, Ching, Kwong-Ming, Poon, Chung-Hei
• Granted Patent: US 8,649,189 B2
• Time in Patent Office: Days
• US Class Current: 363/21.02
• CPC Class Codes: H02M 1/0054 Transistor switching losses periodically suspending operation of switching converter in low power mode H02M1/0035
• CPC Class Codes: H02M 1/4258 using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage H02M1/4241 takes precedence
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current
• 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

Abstract

The invention discloses a power supply having a single stage converter for performing power factor correction to reduce high-frequency harmonics in the input current and performing resonant conversion to achieve zero-voltage switching or zero-current switching for power conversion. The inventive single stage converter includes a switching circuit, a resonant circuit, a power control circuit, and a square wave generator. The switching circuit includes at least one switch and the resonant circuit includes a LLC resonant tank. The power control circuit includes a proportional differential circuit such as a power amplifier configured in a negative feedback topology, and the square wave generator is configured to generate driving signals based on the frequency modulation control signal generated by the comparison of the sensed input current and a user-defined power level input, thereby allowing the square wave generator to regulate the switching operation of the switching circuit.

Claims

1. A power supply for converting an input voltage into an output voltage, comprising:

a switch circuit capable of transferring energy of the input voltage;

a transformer having a primary side and a secondary side for storing energy transferred from the switch circuit at the primary side and transferring stored energy at the primary side to the secondary side according to switching operation of the switch circuit, thereby generating the output voltage;

a resonant circuit connected between the switch circuit and the primary side of the transformer capable of generating resonance to transfer the energy of the input voltage to the primary side of the transformer;

a power control circuit for comparing an input current sensing signal indicative of a sensed input current of the power supply and a power level control input for generating a frequency modulation control signal, wherein the frequency modulation control signal is capable of controlling an output power of the power supply and the suppression of harmonics of an input current of the power supply; and

a square wave generator connected to the power control circuit for generating a driving signal for driving the switch circuit according to the frequency modulation control signal, and wherein a frequency of the driving signal is varied synchronously with a frequency of the frequency modulation control signal, thereby suppressing harmonics of the input current of the power supply and regulating a switching frequency of the switch circuit, so as to regulate an output power of the power supply.

2. A power supply for converting an input voltage into an output voltage, comprising:

a single stage converter for receiving the input voltage and having a switch circuit capable of transferring energy of the input voltage according to switching operation of the switch circuit; and

a transformer connected to the single stage converter and having a primary side and a secondary side for storing energy transferred from the single stage converter at the primary side and transferred energy stored at the primary side to the secondary side according to switching operation of the switch circuit, thereby generating the output voltage;

wherein the single stage converter comprises a resonant circuit connected between the switch circuit and the primary side of the transformer for generating resonance to transfer the energy of the input voltage to the primary side of the transformer, and a power control circuit connected to the switch circuit for regulating the switching operation of the switch circuit to suppress harmonics of an input current of the power supply.

3. The power supply according to claim 2 wherein the power control circuit is configured to compare an input current sensing signal indicative of a sensed input current of the power supply and a power level control input capable of generating a frequency modulation control signal for controlling an output power of the power supply and suppress harmonics of the input current of the power supply.

4. The power supply according to claim 3 wherein the single stage converter further comprises a square wave generator connected to the power control circuit for generating a driving signal for driving the switch circuit according to the frequency modulation control signal, in which the frequency of the driving signal is varied synchronously with the frequency of the frequency modulation control signal, thereby suppressing harmonics of the input current of the power supply and regulating a switching frequency of the switch circuit, and regulating the output power of the power supply.

5. The power supply according to claim 2 wherein the resonant circuit includes a series LLC resonant tank or a parallel LLC resonant tank.

6. The power supply according to claim 2 wherein the power control circuit includes a proportional differential circuit.

7. The power supply according to claim 6 wherein the proportional differential circuit includes a power amplifier, a multiplicity of resistors, and a multiplicity of capacitors configured in a negative feedback topology.

8. The power supply according to claim 7 wherein the power control circuit further includes a reverse current isolation device connected between the proportional differential circuit and the square wave generator for preventing a reverse current from flowing from the square wave generator to the proportional differential circuit.

9. The power supply according to claim 2 further comprising an output capacitor connected to the secondary side of the transformer for generating the output voltage.

10. The power supply according to claim 9 further comprising an output voltage stabilizer connected to the output capacitor for detecting the output voltage to output a feedback signal to the square wave generator, thereby driving the square wave generator to regulate the switching operation of the switch circuit for stabilizing the output voltage.

11. The power supply according to claim 10 further comprising a pair of rectifying diodes connected between the secondary side of the transformer and the output capacitor for rectifying energy of the secondary side of the transformer into a half-wave rectified DC voltage.

12. The power supply according to claim 11 further comprising a buck converter connected between the output capacitor and a load for descending the output voltage generated by the output capacitor to a low DC voltage for powering the load.

13. The power supply according to claim 12 further comprising a hold-up time extension circuit connected between the output capacitor and the buck converter for prolonging an extension time of the output capacitor.

14. The power supply according to claim 2, further comprising:

a bridge rectifier for rectifying the input voltage into a full-wave rectified DC voltage;

a filter circuit connected to an output end of the bridge rectifier for suppressing electromagnetic interference and high-frequency noises of the input voltage and generating a DC voltage analogous to the full-wave rectified DC voltage or a half-wave rectified DC voltage generated by half-wave rectifying the input voltage; and

a current sensor for sensing the input current and generating an input current sensing signal.

15. The power supply according to claim 2 wherein the switch circuit includes a high-side switch and a low-side switch.