SERIES RESONANT CONVERTER

• US 20090290389A1
• Filed: 05/21/2009
• Published: 11/26/2009
• Est. Priority Date: 05/23/2008
• Status: Active Grant

• Current Assignee: Origin Pty Limited (Origin Energy Limited)
• Original Assignee: Origin Electric Company Limited
• Inventors: Saito, Atsushi, Ueno, Shingo, Watanabe, Kiyomi
• Granted Patent: US 8,441,812 B2
• Time in Patent Office: Days
• US Class Current: 363/21.02
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/33571 Half-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 3/33573 Full-bridge at primary side of an isolation transformer
• CPC Class Codes: H02M 3/337 in push-pull configuration H02M3/33576 takes precedence; with self-oscillating arrangements H02M3/3382, H02M3/3385
• 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

A series resonant converter of the present invention includes an inverter circuit having at least a pair of a first and second switching device connected between two input terminals, a transformer having a primary winding and a secondary winding connected to the inverter circuit, a first and second resonant capacitor connected to a secondary side of the transformer and connected in series to each other between two output terminals, a first and second unidirectional device connected in series to each other, and a resonant induction device that is operated along with the first and second resonant capacitor and resonates in series. The first and second unidirectional device are configured such that current does not flow from the first and second resonant capacitor to the input terminal by preventing electric charge of the first and second resonant capacitor from being discharged to a primary side of the transformer.

Claims

1. A series resonant converter, comprising:

an inverter circuit including at least a pair of a first switching device and a second switching device connected between two input terminals;

a transformer, which includes a primary winding and a secondary winding, connected to the inverter circuit;

a first resonant capacitor and a second resonant capacitor connected in series to each other between two output terminals;

a first unidirectional device and a second unidirectional device connected in series to each other between the two output terminals; and

a resonant induction device that is operated along with the first resonant capacitor and the second resonant capacitor and resonates in series, wherein

a connection point of the first resonant capacitor and the second resonant capacitor is connected to one end of the secondary winding of the transformer;

a connection point of the first unidirectional device and the second unidirectional device is connected to the other end of the secondary winding of the transformer;

the first switching device and the second switching device are turned on and off alternately;

the inverter circuit converts DC power inputted from the input terminal and supplies alternating voltage to the output terminal via the transformer; and

the first unidirectional device and the second unidirectional device prevent current from returning from the first resonant capacitor and the second resonant capacitor to the input terminal.

2. The series resonant converter according to claim 1, wherein

the inverter circuit comprises a first feedback diode arranged in parallel with the first switching device and having a reversed polarity opposite to that of the first switching device, and a second feedback diode arranged in parallel with the second switching device and having a reversed polarity opposite to that of the second switching device.

3. The series resonant converter according to claim 1, wherein

a reverse charge control device that prevents reverse direction charge of the first resonant capacitor and the second resonant capacitor is connected in parallel with the first resonant capacitor and the second resonant capacitor, respectively.

4. The series resonant converter according to claim 1, wherein

the inverter circuit comprises any of the following circuit configurations of:

a half-bridge circuit in which the first switching device and the second switching device are connected in series;

a full-bridge circuit connected in parallel with two switching device arms in which the first switching device and the second switching device are connected in series; and

a push-pull type circuit connecting the first switching device with the second switching device between the input terminal and two terminals of the primary winding of the transformer in which an intermediate tap is provided.

5. The series resonant converter according to claim 1, wherein

inductance of the resonant induction device, and capacitance of the first resonant capacitor and capacitance of the second resonant capacitor are selected so that the inductance of the resonant induction device and additive capacitance which adds the capacitance of the first resonant capacitor and the second resonant capacitor are resonated in series at a resonance frequency which is substantially equal to a conversion frequency of the inverter circuit.

6. The series resonant converter according to claim 1, wherein

the first switching device and the second switching device operate at a conversion frequency of the inverter which is below a resonance frequency fixed by the resonant induction device, the first resonant capacitor and the second resonant capacitor.

7. The series resonant converter according to claim 1, wherein

a first field-effect transistor is employed as the first unidirectional device and a second field-effect transistor is employed as the second unidirectional device,

the first field-effect transistor is synchronized with the first switching device of the inverter circuit and turns ON simultaneously therewith, and

the second field-effect transistor performs synchronous rectification by turning on to be synchronous with the second switching device of the inverter circuit.

8. The series resonant converter according to claim 1, wherein

a smoothing capacitor, which has sufficiently higher capacitance than the first resonant capacitor or the second resonant capacitor, is connected in parallel with a series circuit of the first unidirectional device and the second unidirectional device.

9. The series resonant converter according to claim 1, wherein

a resonant inductor imparting at least a portion of the inductance of the resonant induction device is connected in series with the first winding or the second winding of the transformer.

10. The series resonant converter according to claim 1, wherein

a leakage inductance caused by leakage flux between the first winding and the second winding of the transformer is used as at least a portion of the inductance of the resonant induction device.

11. The series resonant converter according to claim 1, wherein

the first switching device or the second switching device are turned off after energy accumulated in the resonant induction device is discharged.

12. The series resonant converter according to claim 2, wherein

in a case in which the first switching device or the second switching device of the inverter circuit are turned off in a condition in which energy is accumulated in the resonant induction device, the energy accumulated in the resonant induction device is supplied to the output terminal via the first feedback diode or the second feedback diode,

in a case in which the first switching device and the second switching device are simultaneously turned off in a condition in which energy is accumulated in the resonant induction device, the energy accumulated in the resonant induction device is returned to the input terminal and supplied to the output terminal via the first feedback diode or the second feedback diode.