DC-TO-AC POWER CONVERSION SYSTEM AND METHOD OF OPERATING THE SAME

• US 20140301123A1
• Filed: 07/12/2013
• Published: 10/09/2014
• Est. Priority Date: 04/03/2013
• Status: Active Grant

• Current Assignee: Delta Electronics Incorporated
• Original Assignee: Delta Electronics Incorporated
• Inventors: LEE, Lei-Ming, KU, Chen-Wei, HUANG, Ho
• Granted Patent: US 9,019,736 B2
• Time in Patent Office: Days
• US Class Current: 363/132
• CPC Class Codes: H02M 1/15 using active elements
• CPC Class Codes: H02M 1/342 Active non-dissipative snubbers
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters
• CPC Class Codes: H02M 7/5387 in a bridge configuration
• CPC Class Codes: H02M 7/53871 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

Abstract

A DC-to-AC power conversion system is provided to convert a DC input voltage into an AC output voltage, which mainly includes a bridge switching circuit, an auxiliary switch circuit, and a control circuit. The bridge switching circuit has a first power switch, a second power switch, a third power switch, and a fourth power switch. The auxiliary switch circuit has a fifth power switch, a sixth power switch, a seventh power switch, and an eighth power switch. The control circuit produces a complementary switching signal pair to control the first and fourth power switches and the second and third power switches, respectively. In addition, the control circuit produces a complementary level signal pair to control the sixth and seventh power switches and the fifth and eighth power switches, respectively.

Claims

1. A DC-to-AC power conversion system converting a DC input voltage into an AC output voltage, the DC-to-AC power conversion system comprising:

an input capacitor set having a first capacitor and a second capacitor, and the first capacitor and the second capacitor connected to a neutral point and configured to receive the DC input voltage;

a bridge switching circuit connected in parallel to the input capacitor set, and the bridge switching circuit having a first bridge arm and a second bridge arm connected in parallel to the first bridge arm;

wherein the first bridge arm is composed of a first power switch and a second power switch connected in series to the first power switch, and the second bridge arm is composed of a third power switch and a fourth power switch connected in series to the third power switch;

an auxiliary switch circuit connected between the neutral point and the bridge switching circuit, and the auxiliary switch circuit having a third bridge arm and a fourth bridge arm connected in parallel to the third bridge arm;

wherein the third bridge arm is composed of a fifth power switch and a sixth power switch connected in series to the fifth power switch, and the fourth bridge arm is composed of a seventh power switch and an eighth power switch connected in series to the seventh power switch;

a filter circuit having a first filter inductor, a second filter inductor, and a filter capacitor;

wherein the filter capacitor is connected between the first filter inductor and the second filter inductor, the first filter inductor is connected to the first bridge arm and the third bridge arm, and the second filter inductor is connected to the second bridge arm and the fourth bridge arm; and

a control circuit configured to produce a complementary switching signal pair and a complementary level signal pair;

wherein the complementary switching signal pair is configured to control the first and fourth power switches and the second and third power switches, respectively;

the complementary level signal pair is configured to control the sixth and seventh power switches and the fifth and eighth power switches, respectively;

wherein the auxiliary switch circuit is configured to provide the energy-releasing loops of the first filter inductor and the second filter inductor to reduce leakage currents of the DC input voltage caused by parasitic capacitance voltages.

2. The DC-to-AC power conversion system in claim 1, wherein the first power switch, the second power switch, the third power switch, and the fourth power switch of the bridge switching circuit are connected in parallel to a first diode, a second diode, a third diode, and a fourth diode, respectively;

the fifth power switch, the sixth power switch, the seventh power switch, and the eighth power switch of the auxiliary switch circuit are connected in parallel to a fifth diode, a sixth diode, a seventh diode, and an eighth diode, respectively.

3. The DC-to-AC power conversion system in claim 2, wherein when the AC output voltage is under the positive half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the first power switch and the fourth power switch and turn off the second power switch and the third power switch at low level;

and the control circuit is configured to produce the complementary level signal pair to turn on the sixth power switch and the seventh power switch at high level and turn off the fifth power switch and the eighth power switch at low level;

when the first filter inductor and the second filter inductor are under the energy-storing operation, an energy-storing loop is sequentially formed by the DC input voltage, the first power switch, the first filter inductor, the AC output voltage, the second filter inductor, the fourth power switch, and the DC input voltage.

4. The DC-to-AC power conversion system in claim 2, wherein when the AC output voltage is under the positive half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the first power switch and the fourth power switch and turn off the second power switch and the third power switch at low level;

and the control circuit is configured to produce the complementary level signal pair to turn on the sixth power switch and the seventh power switch at high level and turn off the fifth power switch and the eighth power switch at low level;

when the first filter inductor and the second filter inductor are under the energy-releasing operation, an energy-releasing loop is sequentially formed by the first filter inductor, the AC output voltage, the second filter inductor, the seventh power switch, the eighth diode, the sixth power switch, the fifth diode, and the first filter inductor.

5. The DC-to-AC power conversion system in claim 2, wherein when the AC output voltage is under the negative half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the second power switch and the third power switch and turn off the first power switch and the fourth power switch at low level;

and the control circuit is configured to produce the complementary level signal pair to turn on the fifth power switch and the eighth power switch at high level and turn off the sixth power switch and the seventh power switch at low level;

when the first filter inductor and the second filter inductor are under the energy-storing operation, an energy-storing loop is sequentially formed by the DC input voltage, the third power switch, the second filter inductor, the AC output voltage, the first filter inductor, the second power switch, and the DC input voltage.

6. The DC-to-AC power conversion system in claim 2, wherein when the AC output voltage is under the negative half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the second power switch and the third power switch and turn off the first power switch and the fourth power switch at low level;

and the control circuit is configured to produce the complementary level signal pair to turn on the fifth power switch and the eighth power switch at high level and turn off the sixth power switch and the seventh power switch at low level;

when the first filter inductor and the second filter inductor are under the energy-releasing operation, an energy-releasing loop is sequentially formed by the second filter inductor, the AC output voltage, the first filter inductor, the fifth power switch, the sixth diode, the eighth power switch, the seventh diode, and the second filter inductor.

7. The DC-to-AC power conversion system in claim 1, wherein the first capacitor and the second capacitor are connected to a neutral point to maintain a voltage across the first capacitor and a voltage across the second capacitor are equal to a half of the DC input voltage.

8. A DC-to-AC power conversion system converting a DC input voltage into an AC output voltage, the DC-to-AC power conversion system comprising:

an input capacitor set having a first capacitor and a second capacitor, and the first capacitor and the second capacitor connected to a neutral point and configured to receive the DC input voltage;

a first bridge switching circuit connected in parallel to the input capacitor set, and the first bridge switching circuit having a first bridge arm and a second bridge arm connected in parallel to the first bridge arm;

wherein the first bridge arm is composed of a first power switch and a fifth diode connected in series to the first power switch, and the second bridge arm is composed of a second power switch and a sixth diode connected in series to the second power switch;

a first auxiliary switch circuit connected between the neutral point and the first bridge switching circuit, and the first auxiliary switch circuit having a third bridge arm and a fourth bridge arm connected in parallel to the third bridge arm;

wherein the third bridge arm is composed of a third power switch and a seventh diode connected in series to the third power switch, and the fourth bridge arm is composed of a fourth power switch and an eighth diode connected in series to the fourth power switch;

a second bridge switching circuit connected in parallel to the input capacitor set, and the second bridge switching circuit having a first bridge arm and a second bridge arm connected in parallel to the first bridge arm;

wherein the first bridge arm is composed of a first power switch and a fifth diode connected in series to the first power switch, and the second bridge arm is composed of a second power switch and a sixth diode connected in series to the second power switch;

a second auxiliary switch circuit connected between the neutral point and the second bridge switching circuit, and the second auxiliary switch circuit having a third bridge arm and a fourth bridge arm connected in parallel to the third bridge arm;

wherein the third bridge arm is composed of a third power switch and a seventh diode connected in series to the third power switch, and the fourth bridge arm is composed of a fourth power switch and an eighth diode connected in series to the fourth power switch;

a first filter circuit having a first filter inductor, a second filter inductor, and a filter capacitor;

wherein the filter capacitor is connected between the first filter inductor and the second filter inductor, the first filter inductor is connected to the first bridge arm of the first bridge switching circuit and the third bridge arm of the first auxiliary switch circuit, and the second filter inductor is connected to the second bridge arm of the first bridge switching circuit and the fourth bridge arm of the first auxiliary switch circuit; and

a second filter circuit having a first filter inductor, a second filter inductor, and the filter capacitor;

wherein the filter capacitor is connected between the first filter inductor and the second filter inductor, the first filter inductor is connected to the first bridge arm of the second bridge switching circuit and the third bridge arm of the second auxiliary switch circuit, and the second filter inductor is connected to the second bridge arm of the second bridge switching circuit and the fourth bridge arm of the second auxiliary switch circuit; and

a control circuit configured to produce a complementary switching signal pair and a complementary level signal pair;

wherein the complementary switching signal pair is configured to control the first and second power switches of the first bridge switching circuit and the first and second power switches of the second bridge switching circuit, respectively;

the complementary level signal pair is configured to control the third and fourth power switches of the first auxiliary switch circuit and the third and fourth power switches of the second auxiliary switch circuit, respectively;

wherein the first auxiliary switch circuit is configured to provide the energy-releasing loops of the first filter inductor and the second filter inductor of the first filter circuit and the second auxiliary switch circuit is configured to provide the energy-releasing loops of the first filter inductor and the second filter inductor of the second filter circuit to reduce leakage currents of the DC input voltage caused by parasitic capacitance voltages.

9. The DC-to-AC power conversion system in claim 8, wherein the first power switch and the second power switch of the first bridge switching circuit are connected in parallel to a first diode and a second diode, respectively;

the third power switch and the fourth power switch of the first auxiliary switch circuit are connected in parallel to a third diode and a fourth diode, respectively;

the first power switch and the second power switch of the second bridge switching circuit are connected in parallel to a first diode and a second diode, respectively;

the third power switch and the fourth power switch of the second auxiliary switch circuit are connected in parallel to a third diode and a fourth diode, respectively.

10. The DC-to-AC power conversion system in claim 9, wherein when the AC output voltage is under the positive half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the first power switch and the second power switch of the first bridge switching circuit and turn off the first power switch and the second power switch of the second bridge switching circuit;

and the control circuit is configured to produce the complementary level signal pair to turn on the third power switch and the fourth power switch of the first auxiliary switch circuit at high level and turn off the third power switch and the fourth power switch of the second auxiliary switch circuit at low level;

when the first filter inductor and the second filter inductor are under the energy-storing operation, an energy-storing loop is sequentially formed by the DC input voltage, the first power switch, the first filter inductor, the AC output voltage, the second filter inductor, the second power switch, and the DC input voltage.

11. The DC-to-AC power conversion system in claim 9, wherein when the AC output voltage is under the positive half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the first power switch and the second power switch of the first bridge switching circuit and turn off the first power switch and the second power switch of the second bridge switching circuit;

and the control circuit is configured to produce the complementary level signal pair to turn on the third power switch and the fourth power switch of the first auxiliary switch circuit at high level and turn off the third power switch and the fourth power switch of the second auxiliary switch circuit at low level;

when the first filter inductor and the second filter inductor are under the energy-releasing operation, an energy-releasing loop is sequentially formed by the first filter inductor, the AC output voltage, the second filter inductor, the fourth power switch, the eighth diode, the third power switch, the seventh diode, and the first filter inductor.

12. The DC-to-AC power conversion system in claim 9, wherein when the AC output voltage is under the negative half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the first power switch and the second power switch of the second bridge switching circuit and turn off the first power switch and the second power switch of the first bridge switching circuit;

and the control circuit is configured to produce the complementary level signal pair to turn on the third power switch and the fourth power switch of the second auxiliary switch circuit at high level and turn off the third power switch and the fourth power switch of the first auxiliary switch circuit at low level;

when the first filter inductor and the second filter inductor are under the energy-storing operation, an energy-storing loop is sequentially formed by the DC input voltage, the first power switch, the first filter inductor, the AC output voltage, the second filter inductor, the second power switch, and the DC input voltage.

13. The DC-to-AC power conversion system in claim 9, wherein when the AC output voltage is under the negative half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the first power switch and the second power switch of the second bridge switching circuit and turn off the first power switch and the second power switch of the first bridge switching circuit;

and the control circuit is configured to produce the complementary level signal pair to turn on the third power switch and the fourth power switch of the second auxiliary switch circuit at high level and turn off the third power switch and the fourth power switch of the first auxiliary switch circuit at low level;

when the first filter inductor and the second filter inductor are under the energy-releasing operation, an energy-releasing loop is sequentially formed by the first filter inductor, the AC output voltage, the second filter inductor, the fourth power switch, the eighth diode, the third power switch, the seventh diode, and the first filter inductor.

14. The DC-to-AC power conversion system in claim 8, wherein the first capacitor and the second capacitor are connected to a neutral point to maintain a voltage across the first capacitor and a voltage across the second capacitor are equal to a half of the DC input voltage.

15. A method of operating a DC-to-AC power conversion system, the DC-to-AC power conversion system converting a DC input voltage into an AC output voltage, the method comprising following steps:

(a) providing an input capacitor set, the input capacitor set having a first capacitor and a second capacitor, and the first capacitor and the second capacitor connected to a neutral point and configured to receive the DC input voltage;

(b) providing a bridge switching circuit, the bridge switching circuit connected in parallel to the input capacitor set, and the bridge switching circuit having a first bridge arm and a second bridge arm connected in parallel to the first bridge arm;

wherein the first bridge arm is composed of a first power switch and a second power switch connected in series to the first power switch, and the second bridge arm is composed of a third power switch and a fourth power switch connected in series to the third power switch;

(c) providing an auxiliary switch circuit, the auxiliary switch circuit connected between the neutral point and the bridge switching circuit, and the auxiliary switch circuit having a third bridge arm and a fourth bridge arm connected in parallel to the third bridge arm;

wherein the third bridge arm is composed of a fifth power switch and a sixth power switch connected in series to the fifth power switch, and the fourth bridge arm is composed of a seventh power switch and an eighth power switch connected in series to the seventh power switch;

(d) providing a filter circuit, the filter circuit having a first filter inductor, a second filter inductor, and a filter capacitor;

wherein the filter capacitor is connected between the first filter inductor and the second filter inductor, the first filter inductor is connected to the first bridge arm and the third bridge arm, and the second filter inductor is connected to the second bridge arm and the fourth bridge arm; and

(e) providing a control circuit, the control circuit configured to produce a complementary switching signal pair and a complementary level signal pair;

wherein the complementary switching signal pair is configured to control the first and fourth power switches and the second and third power switches, respectively;

the complementary level signal pair is configured to control the sixth and seventh power switches and the fifth and eighth power switches, respectively.

16. The method of operating the DC-to-AC power conversion system in claim 15, wherein the first power switch, the second power switch, the third power switch, and the fourth power switch of the bridge switching circuit are connected in parallel to a first diode, a second diode, a third diode, and a fourth diode, respectively;

the fifth power switch, the sixth power switch, the seventh power switch, and the eighth power switch of the auxiliary switch circuit are connected in parallel to a fifth diode, a sixth diode, a seventh diode, and an eighth diode, respectively;

wherein the first capacitor and the second capacitor are connected to a neutral point to maintain a voltage across the first capacitor and a voltage across the second capacitor are equal to a half of the DC input voltage.

17. The method of operating the DC-to-AC power conversion system in claim 16, wherein when the AC output voltage is under the positive half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the first power switch and the fourth power switch and turn off the second power switch and the third power switch at low level;

and the control circuit is configured to produce the complementary level signal pair to turn on the sixth power switch and the seventh power switch at high level and turn off the fifth power switch and the eighth power switch at low level;

when the first filter inductor and the second filter inductor are under the energy-storing operation, an energy-storing loop is sequentially formed by the DC input voltage, the first power switch, the first filter inductor, the AC output voltage, the second filter inductor, the fourth power switch, and the DC input voltage.

18. The method of operating the DC-to-AC power conversion system in claim 16, wherein when the AC output voltage is under the positive half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the first power switch and the fourth power switch and turn off the second power switch and the third power switch at low level;

and the control circuit is configured to produce the complementary level signal pair to turn on the sixth power switch and the seventh power switch at high level and turn off the fifth power switch and the eighth power switch at low level;

when the first filter inductor and the second filter inductor are under the energy-releasing operation, an energy-releasing loop is sequentially formed by the first filter inductor, the AC output voltage, the second filter inductor, the seventh power switch, the eighth diode, the sixth power switch, the fifth diode, and the first filter inductor.

19. The method of operating the DC-to-AC power conversion system in claim 16, wherein when the AC output voltage is under the negative half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the second power switch and the third power switch and turn off the first power switch and the fourth power switch at low level;

and the control circuit is configured to produce the complementary level signal pair to turn on the fifth power switch and the eighth power switch at high level and turn off the sixth power switch and the seventh power switch at low level;

when the first filter inductor and the second filter inductor are under the energy-storing operation, an energy-storing loop is sequentially formed by the DC input voltage, the third power switch, the second filter inductor, the AC output voltage, the first filter inductor, the second power switch, and the DC input voltage.

20. The method of operating the DC-to-AC power conversion system in claim 16, wherein when the AC output voltage is under the negative half-cycle operation, the control circuit is configured to produce the complementary switching signal pair to switch the second power switch and the third power switch and turn off the first power switch and the fourth power switch at low level;

and the control circuit is configured to produce the complementary level signal pair to turn on the fifth power switch and the eighth power switch at high level and turn off the sixth power switch and the seventh power switch at low level;

when the first filter inductor and the second filter inductor are under the energy-releasing operation, an energy-releasing loop is sequentially formed by the second filter inductor, the AC output voltage, the first filter inductor, the fifth power switch, the sixth diode, the eighth power switch, the seventh diode, and the second filter inductor.