Resonant converters including flying capacitors

• US 9,871,467 B2
• Filed: 05/19/2016
• Issued: 01/16/2018
• Est. Priority Date: 05/19/2016
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Schweiz AG (ABB Limited)
• Inventors: Liang, Jiaqi, Suryanarayana, Harish, Kittila, Jukka-Pekka
• Primary Examiner(s): PATEL, RAJNIKANT B
• Application Number:
  US15/159,227
• Publication Number:
  US 20170338748A1
• Time in Patent Office: 607 Days
• Field of Search: 363 16- 20, 363 2103, 363 39, 363 5601, 363 95, 363 97, 363 98, 363131, 363132
• 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 1/0095 Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 7/4811 having auxiliary actively switched resonant commutation circuits connected to intermediate DC voltage or between two push-pull branches
• CPC Class Codes: H02M 7/4815 Resonant converters H02M7/4811 and H02M7/4826 take precedence
• CPC Class Codes: H02M 7/483 Converters with outputs that each can have more than two voltages levels
• CPC Class Codes: H02M 7/4837 Flying capacitor converters
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters
• 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

Unique systems, methods, techniques and apparatuses of zero-voltage transition pulse width modulation resonant converters are disclosed. One exemplary embodiment is a zero-voltage transition PWM resonant converter comprising a DC bus, a first switching device, a second switching device, a resonant tank circuit, an auxiliary circuit having a flying capacitor and a plurality of auxiliary switching devices, and a controller. The controller is structured to control the first switching device, the second switching device, and the plurality of auxiliary switching devices to provide resonant operation of the tank circuit effective to provide a substantially zero voltage condition across the first switching device when turning the first switching device on or off and to provide a substantially zero voltage condition across the second switching device when turning the second switching device on or off.

Claims

1. A zero-voltage transition PWM resonant converter comprising:

a DC bus including a first rail and a second rail;

a first switching device coupled with the first rail and a converter output node;

a second switching device coupled with the second rail and the converter output node;

a resonant tank circuit comprising a first resonant capacitor coupled in parallel with the first switching device, a second resonant capacitor coupled in parallel with the second switching device, and a resonant inductor coupled with the converter output node;

an auxiliary circuit including a plurality of auxiliary switching devices coupled in series between the first rail and the second rail and a flying capacitor coupled in parallel across two of the auxiliary switching devices, the resonant inductor being coupled to a node intermediate the said two of the auxiliary switching devices; and

a controller structured to control the first switching device, the second switching device, and the plurality of auxiliary switching devices to provide resonant operation of the tank circuit effective to provide a substantially zero voltage condition across the first switching device when turning the first switching device on or off and to provide a substantially zero voltage condition across the second switching device when turning the second switching device on or off,

wherein after all of the plurality of switching devices are opened, current no longer flows through the resonant inductor.

2. The converter of claim 1 wherein the plurality of auxiliary switching devices comprise first, second, third and fourth auxiliary switching devices coupled in series between the first rail and the second rail, the flying capacitor is coupled in parallel across the second and third auxiliary switching devices, and the resonant inductor is coupled to a node intermediate the second and third auxiliary switching devices.

3. The converter of claim 2 wherein the controller is structured to execute a commutation scheme in which the first auxiliary switching device is turned on at a first time with the first switch off and the second switch on effective to increase the resonant inductor current and the second switch is turned off under the substantially zero voltage condition at a second time greater than the first time effective to provide resonant operation of the tank circuit.

4. The converter of claim 3 wherein the first switching device is turned on at a third time greater than the second time when the voltage across the first switching device become substantially zero due to resonant operation of the tank circuit.

5. The converter of claim 4 wherein the flying capacitor comprises a film capacitor.

6. A zero-voltage transition converter coupled to a direct current (DC) power source having a positive pole and a negative pole, the converter comprising:

a first primary switching device having a first terminal electrically coupled to the positive pole of the DC power source, and a second terminal electrically coupled to a load;

a second primary switching device having a first terminal electrically coupled to the load and a second terminal coupled to the negative pole of the DC power source;

a first resonant capacitor coupled in parallel to the first primary switching device;

a second resonant capacitor coupled in parallel to the second primary switching device;

a flying capacitor (FC) circuit electrically coupled to the power source and the load, the FC circuit comprising at least one flying capacitor and at least four FC switching devices;

a resonant inductor electrically coupled with the first primary switch, second primary switch, the load and the FC circuit; and

a controller structured to operate the first primary switching device and the second primary switching device by opening and closing the first primary switching device and the second primary switching device so as to convert DC power from the DC power source into output power and transmit the output power to the load,

wherein the controller is structured to operate the FC switching devices so as to generate substantially zero voltage switching conditions across the first primary switching device and the second primary switching device during the opening and closing of the first primary switching device and the second primary switching device,

wherein the FC circuit and resonant tank are structured to allow no current to pass through the resonant inductor after opening one of the FC switching devices, and

wherein the controller is structured to generate a resonating current by operating the FC switching devices such that a current flows through the resonant inductor.

7. The converter of claim 6, wherein the controller is structured to transmit a plurality of pulse width modulation signals to operate the first primary switching device, the second primary switching device, and the FC switching devices, the pulse width modulation signals causing either the closing of one of said devices to allow current to flow through the switching device or the opening of said one of said devices to prevent current from flowing through the device in at least one direction.

8. The converter of claim 7, wherein the controller opens the first primary switching device during substantially zero voltage switching conditions by supplying an equal voltage to the first and second terminal of the first primary switching device and opens the second primary switching device during substantially zero voltage switching conditions by supplying an equal voltage to the first and second terminal of the second primary switching device.

9. The converter of claim 8, wherein the controller operates the FC switching devices so as to charge the resonant inductor before the controller opens the one of the first primary switching device and the second primary switching device.

10. The converter of claim 7, wherein the controller is structured to close one of the first primary switching device and the second primary switching device during a zero voltage switching condition by providing a current through the resonant inductor by operating the FC switching devices such that the resonant inductor, the first resonant capacitor and the second resonant capacitor achieve resonance, and closing the first primary switching device or the second primary switching device in response to achieving the zero voltage switching condition.

11. The converter of claim 10, wherein the controller is structured to open one of the FC switching devices following the controller closing of the first primary switching device or the second primary switching device in response to a zero current condition at the FC switching device.

12. The converter of claim 6, wherein the FC circuit comprises one flying capacitor having an anode and a cathode, and four FC switching devices, the first FC switching device having a first terminal electrically coupled to the positive poles of the DC power source and a second terminal electrically coupled to the cathode of the flying capacitor, the second FC switching device having a first terminal electrically coupled to the cathode of the flying capacitor and a second terminal electrically coupled to the inductive element;

the third FC switching device having a first terminal electrically coupled to the inductive element and a second terminal electrically coupled to the anode of the flying capacitor; and

the fourth FC switching device having a first terminal electrically coupled to the anode of the flying capacitor and a second terminal electrically coupled to the negative pole of the DC power source.

13. The converter of claim 6, wherein the converter additionally comprises a charging circuit structured to charge the flying capacitor wherein the charging circuit is coupled between the DC power source and the flying capacitor circuit, the charging circuit comprising a switching device and a resistive element coupled in parallel.

14. The converter of claim 13, wherein the converter additionally comprises resistors coupled in parallel to at least one of the FC switching devices, the resistance of each resistor being sufficient to allow current to flow to the flying capacitor.

15. The converter of claim 6, wherein the resonant inductor comprises a soft-saturation magnetic material.

16. A method for generating an output power by operating a pulse width modulation converter coupled to a DC power source comprising:

operating circuitry including

a flying capacitor circuit having a flying capacitor and a plurality of semiconductor switches coupled in parallel with the DC power source,

a pair of primary semiconductor switches coupled in parallel with the DC power source,

a resonant tank circuit having a resonant inductor and two resonant capacitors, the resonant tank circuit coupled with the flying capacitor circuit, the pair of primary switches, and a load;

generating a resonating current in the resonant tank by operating the flying capacitor circuit such that the voltage across one of the primary semiconductor switches is a substantially zero voltage condition;

opening one switch of the primary semiconductor switches;

closing the other of the pair of primary semiconductor switches in a substantially zero voltage condition; and

reducing the current in the resonant inductor by generating a midpoint voltage with the flying capacitor circuit.

17. The method of claim 16, wherein the output power is alternating current power.

18. The method of claim 16, additionally comprising charging the resonant inductor by opening a semiconductor device of the flying capacitor circuit between the DC power source and the flying capacitor.

19. The method of claim 16, wherein the substantially zero voltage condition is a voltage with a magnitude of zero or a small percentage of the DC power source voltage.

20. The method of claim 19, wherein the substantially zero voltage condition is a voltage with a magnitude less than 20% of the DC power source voltage.