CONVERTER SYSTEM

• US 20130234641A1
• Filed: 07/31/2012
• Published: 09/12/2013
• Est. Priority Date: 03/09/2012
• Status: Active Grant

• Current Assignee: Delta Electronics Incorporated
• Original Assignee: Delta Electronics Incorporated
• Inventors: Tan, Jing-Tao, LI, Lin, Wu, Hong-Yang
• Granted Patent: US 8,917,047 B2
• Time in Patent Office: Days
• US Class Current: 318/503
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02M 7/493 the static converters being arranged for operation in parallel
• CPC Class Codes: H02P 27/08 with pulse width modulation

Abstract

The present disclosure discloses a converter system, which at least includes the first and second back-to-back converters. The first back-to-back converter includes a first rectifier module and a first inverter module. The first rectifier module is used to convert a first AC voltage to a first DC voltage. The first inverter module is used to convert the first DC voltage to a second AC voltage. The second back-to-back converter includes a second rectifier module and a second inverter module. The second rectifier module is used to convert the first AC voltage to a second DC voltage. The second inverter module is used to convert the second DC voltage to the second AC voltage. The converter system can suppress the circular current through the synchronous operation of the first and second rectifiers or the synchronous operation of the first and second inverters.

Claims

1. A converter system comprising:

a first back-to-back converter comprising;

a first rectifier module comprising a first rectifier and a first controller, wherein the first rectifier has an input side and an output side so as to convert a first AC voltage to a first DC voltage, and the first rectifier is controlled by the first controller; and

a first inverter module comprising a first inverter and a third controller, wherein the first inverter has an input side and an output side so as to invert the first DC voltage to a second AC voltage, and the first inverter is controlled by the third controller; and

a second back-to-back converter comprising;

a second rectifier module comprising a second rectifier and a second controller, wherein the second rectifier has an input side and an output side so as to convert the first AC voltage to a second DC voltage, the second rectifier is controlled by the second controller, and the input side of the second rectifier is connected to the input side of the first rectifier in parallel; and

a second inverter module comprising a second inverter and a fourth controller, wherein the second inverter has an input side and an output side, so as to invert the second DC voltage to the second AC voltage, the second inverter is controlled by the fourth controller, and the output side of the second inverter is connected to the output side of the first inverter in parallel,

wherein the first and second rectifiers have a rectifier frequency, the first and second inverters have an inverter frequency, and a circular current of the converter system is suppressed through the synchronous operation of the first and second rectifiers or through the synchronous operation of the first and second inverters.

2. The converter system of claim 1, wherein the first and second rectifiers are electrically connected to a power generator, and the first and second inverters are electrically connected to an AC grid.

3. The converter system of claim 2, wherein the power generator is a three-phase motor.

4. The converter system of claim 1, wherein the first and second rectifiers are electrically connected to an AC grid, and the first and second inverters are electrically connected to a power generator.

5. The converter system of claim 4, wherein the power generator is a three-phase motor.

6. The converter system of claim 1, wherein when the rectifier frequency is smaller than the inverter frequency, the first and second rectifier modules receive a rectifier synchronous signal so that the first and second rectifiers operate synchronously, and the period of the rectifier synchronous signal is N times the rectifier period of the first or second rectifier, wherein N is an integer and the rectifier period and the rectifier frequency are reciprocals of each other.

7. The converter system of claim 6, further comprising a signal generation circuit so as to generate the rectifier synchronous signal, wherein each of the PWM carrier generator of the first controller and the PWM carrier generator of the second controller receives the rectifier synchronous signal and outputs a synchronous PWM carrier signal.

8. The converter system of claim 7, wherein each of the first and second controllers comprises:

a power controller used to receive a parameter reflecting the AC power and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

9. The converter system of claim 7, wherein the signal generation circuit is a differential circuit or a 555 circuit.

10. The converter system of claim 9, wherein each of the first and second controllers comprises:

a power controller used to receive a parameter reflecting the AC power and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

11. The converter system of claim 1, wherein when the rectifier frequency is smaller than the inverter frequency, one of the first and second controllers generates and sends a rectifier synchronous signal to the other so that the first and second rectifiers operate synchronously, wherein each of the PWM carrier generator of the first controller and the PWM carrier generator of the second controller outputs a synchronous PWM carrier signal according to the rectifier synchronous signal.

12. The converter system of claim 11, wherein each of the first and second controllers comprises:

a power controller used to receive a parameter reflecting the AC power and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

13. The converter system of claim 1, wherein when the rectifier frequency is larger than the inverter frequency, the first and second inverter modules receive an inverter synchronous signal so that the first and second inverters operate synchronously, and the period of the inverter synchronous signal is M times the inverter period of the first or second inverter, wherein M is an integer and the inverter period and the inverter frequency are reciprocals of each other.

14. The converter system of claim 13, further comprising a signal generation circuit so as to generate the inverter synchronous signal, wherein each of the PWM carrier generator of the third controller and the PWM carrier generator of the fourth controller receives the inverter synchronous signal and outputs a synchronous PWM carrier signal.

15. The converter system of claim 14, wherein each of the third and fourth controllers comprises:

a voltage regulator used to receive a corresponding DC voltage and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

16. The converter system of claim 14, wherein the signal generation circuit is a differential circuit or a 555 circuit.

17. The converter system of claim 16, wherein each of the third and fourth controllers comprises:

a voltage regulator used to receive a corresponding DC voltage and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

18. The converter system of claim 1, wherein when the rectifier frequency is larger than the inverter frequency, one of the third and fourth controllers generates and sends an inverter synchronous signal to the other so that the first and second inverters operate synchronously, wherein each of the PWM carrier generator of the third controller and the PWM carrier generator of the fourth controller outputs a synchronous PWM carrier signal according to the inverter synchronous signal.

19. The converter system of claim 18, wherein each of the third and fourth controllers comprises:

a voltage regulator used to receive a corresponding DC voltage and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

20. The converter system of claim 1, wherein the first back-to-back converter comprises a first storage unit for storing the first DC voltage, which is arranged between the first rectifier and the first inverter, and the second back-to-back converter comprises a second storage unit for storing the second DC voltage, which is arranged between the second rectifier and the second inverter.

21. The converter system of claim 20, wherein each of the first storage unit and the second storage unit is a DC bus capacitor.

22. The converter system of claim 21, wherein the DC bus capacitor of the first back-to-back converter is connected to the DC bus capacitor of the second back-to-back converter in parallel.

23. The converter system of claim 1, wherein the first back-to-back converter and the second back-to-back converter form a symmetric bridge circuit.

24. The converter system of claim 23, wherein the first back-to-back converter and the second back-to-back converter have a two-level or three-level structure.

25. The converter system of claim 1, wherein the first back-to-back converter and the second back-to-back converter form an asymmetric bridge circuit.

26. The converter system of claim 25, wherein one of the first rectifier and the first inverter in the first back-to-back converter has a two-level structure, and the other has a three-level structure;

and one of the second rectifier and the second inverter in the second back-to-back converter has a two-level structure, and the other has a three-level structure.

27. The converter system of claim 25, wherein switches of the first rectifier are different from those of the first inverter, and switches of the second rectifier are different from those of the second inverter.

28. The converter system of claim 25, wherein circuit connection of the first rectifier is different from that of the first inverter, and circuit connection of the second rectifier is different from that of the second inverter.

29. A converter system comprising:

a first back-to-back converter comprising;

a first rectifier module comprising a first rectifier and a first controller, wherein the first rectifier has an input side and an output side so as to convert a first AC voltage to a first DC voltage, and the first rectifier is controlled by the first controller; and

a first inverter module comprising a first inverter and a third controller, wherein the first inverter has an input side and an output side so as to invert the first DC voltage to a second AC voltage, and the first inverter is controlled by the third controller; and

a second back-to-back converter comprising;

a second rectifier module comprising a second rectifier and a second controller, wherein the second rectifier has an input side and an output side, so as to convert the first AC voltage to a second DC voltage, the second rectifier is controlled by the second controller, and the input side of the second rectifier is connected to the input side of the first rectifier in parallel; and

a second inverter module comprising a second inverter and a fourth controller, wherein the second inverter has an input side and an output side, so as to invert the second DC voltage to the second AC voltage, the second inverter is controlled by the fourth controller, and the output side of the second inverter is connected to the output side of the first inverter in parallel,

wherein the circular current of the converter system is suppressed simultaneously through the synchronous operation of the first and second rectifiers and through the synchronous operation of the first and second inverters.

30. The converter system of claim 29, further comprising a first signal generation circuit so as to generate a rectifier synchronous signal, wherein each of the PWM carrier generator of the first controller and the PWM carrier generator of the second controller receives the rectifier synchronous signal and outputs a synchronous PWM carrier signal, so that the first and second rectifiers operate synchronously.

31. The converter system of claim 30, wherein each of the first and second controllers comprises:

a power controller used to receive a parameter reflecting the AC power and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

32. The converter system of claim 30, wherein the first signal generation circuit is a differential circuit or a 555 circuit.

33. The converter system of claim 32, wherein each of the first and second controllers comprises:

a power controller used to receive a parameter reflecting the AC power and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

34. The converter system of claim 29, wherein one of the first and second controllers generates and sends a rectifier synchronous signal to the other so that the first and second rectifiers operate synchronously, wherein each of the PWM carrier generator of the first controller and the PWM carrier generator of the second controller outputs a synchronous PWM carrier signal according to the rectifier synchronous signal.

35. The converter system of claim 34, wherein each of the first and second controllers comprises:

a power controller used to receive a parameter reflecting the AC power and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

36. The converter system of claim 29, further comprising a second signal generation circuit so as to generate an inverter synchronous signal, wherein each of the PWM carrier generator of the third controller and the PWM carrier generator of the fourth controller receives the inverter synchronous signal and outputs a synchronous PWM carrier signal, so that the first and second inverters operate synchronously.

37. The converter system of claim 36, wherein each of the third and fourth controllers comprises:

a voltage regulator used to receive a corresponding DC voltage and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

38. The converter system of claim 36, wherein the second signal generation circuit is a differential circuit or a 555 circuit.

39. The converter system of claim 38, wherein each of the third and fourth controllers comprises:

a voltage regulator used to receive a corresponding DC voltage and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.

40. The converter system of claim 29, wherein one of the third and fourth controllers generates and sends an inverter synchronous signal to the other so that the first and second inverters operate synchronously, wherein each of the PWM carrier generator of the third controller and the PWM carrier generator of the fourth controller outputs a synchronous PWM carrier signal according to the inverter synchronous signal.

41. The converter system of claim 40, wherein each of the third and fourth controllers comprises:

a voltage regulator used to receive a corresponding DC voltage and output a current reference signal;

a current regulator for receiving the current reference signal and outputting a voltage reference signal; and

a control signal generator used to compare the voltage reference signal with the synchronous PWM carrier signal so as to generate a PWM control signal.