Power conversion system

• US 5,177,677 A
• Filed: 03/06/1990
• Issued: 01/05/1993
• Est. Priority Date: 03/08/1989
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kimura, Akira, Takahashi, Youji, Abe, Atsushi, Nakamura, Kiyoshi, Nakata, Kiyoshi, Tsutsui, Yoshio
• Primary Examiner(s): Voeltz, Emanuel T.
• Application Number:
  US07/489,324
• Time in Patent Office: 1,036 Days
• Field of Search: 363/37, 363/84, 363/85, 363/87, 363/89, 363/125, 363/127, 320/14, 320/21, 320/44
• US Class Current: 363/89
• CPC Class Codes: H02J 7/1492 by means of controlling devices between the generator output and the battery
• CPC Class Codes: H02M 7/219 in a bridge configuration
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Abstract

A power conversion system is disclosed in which a direct current is taken out of an AC power supply of variable frequency and variable voltage through a PWM converter in such a manner that in a region of low source voltage, the converter input current is limited to a predetermined value to maximize the DC power taking the voltage drop of the power supply into consideration with the power factor of "1" of the power supply, and when the current reaches an allowable maximum, it is limited to that value. In a region of high source voltage, on the other hand, the quadrature component of the input voltage applied to the source voltage is controlled preferentially in a manner to control the converter input voltage below a predetermined value, thus making it possible to secure the maximum power available from the converter over the entire range of operation. If a battery is connected to the DC side, a cooperative operation is made possible while the battery is charged properly.

Claims

1. A power conversion system comprising a power converter for converting an AC signals of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, and means for limiting an input current of the power converter in accordance with a signal relating to one of the voltage and frequency of the AC power supply.

7. A power conversion system according to claim 1, further comprising a DC filter circuit inserted between the power converter and the load device.

2. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, means for limiting an input current of the power converter in accordance with a signal relating to one of the voltage and frequency of the AC power supply, and a battery connected to the DC output side of said power converter.

3. A power conversion system according to claim 2, wherein the DC output voltage of the power converter is controlled in accordance with a current flowing through the battery current.

4. A power conversion system according to claim 2, further comprising means inserted between the power converter and the battery for preventing a reverse flow of a current from the battery to the power converter.

5. A power conversion system according to claim 2, further comprising means for limiting the DC output voltage of the power converter within a predetermined range.

6. A power conversion system according to claim 2, further comprising a DC filter circuit inserted between the power converter and the load device.

8. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, and means for limiting a reactance voltage of the AC power supply in accordance with a signal relating to one of the voltage and frequency of the AC power supply.

9. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, means for estimating a value of a signal relating to one of the voltage and frequency of the AC power supply in accordance with an input voltage or an input current of the power converter, and means for limiting an input current of the power converter according to the estimated value.

10. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, means for limiting an input current of the power converter in accordance with a signal relating to one of the voltage and frequency of the AC power supply, and means for controlling the input current of said power converter by a compensation coefficient which is adjusted in accordance with a signal relating to the frequency of the AC power supply.

11. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, and means for setting a component of an input voltage of the power converter in phase with the voltage of the power supply according to a quadrature component of the input voltage of the power converter with respect to the voltage of the power supply.

17. A power conversion system according to claim 11, wherein the means for setting the in-phase component includes means for setting a maximum value of the in-phase component based on the quadrature component of the input voltage of the power supply and means for setting the in-phase component at a value less than the maximum value.

12. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, means for setting a component of an input voltage of the power converter in phase with the voltage of the power supply according to a quadrature component of the input voltage of the power converter with respect to the voltage of the power supply, and a battery connected at the DC output side of the power converter.

13. A power conversion system according to claim 12, wherein the DC output voltage of the power converter is controlled in accordance with a current flowing through the battery current.

14. A power conversion system according to claim 12, further comprising means inserted between the power converter and the battery for preventing a reverse flow of a current from the battery to the power converter.

15. A power conversion system according to claim 12, further comprising means for limiting the DC output voltage of the power converter within a predetermined range.

16. A power conversion system according to claim 12, further comprising a DC filter circuit inserted between the power converter and the load device.

18. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, means for regulating a phase of an input current of the power supply, and a battery connected at the DC output side of the power converter.

19. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, means for setting a component of an input voltage of the power converter in phase with the voltage of the power supply according to a quadrature component of the input voltage of the power converter with respect to the voltage of the power supply, and means for controlling an input current of said power converter by a compensation coefficient adjusted in accordance with a signal relating to the frequency of the AC power supply.

20. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, means for limiting an input current of the power converter in accordance with a signal relating to one of the voltage and frequency of the AC power supply, and means for setting a component of an input voltage of the power converter in phase with the voltage of the power supply according to a quadrature component of the input voltage of the power converter with respect to the voltage of the power supply.

21. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, means for limiting an input current of the power converter in accordance with a signal relating to one of the voltage and frequency of the AC power supply, means for setting a component of an input voltage of the power converter in-phase with the voltage of the power supply according to a quadrature component of the input voltage of the power converter with respect to the voltage of the power supply, and a battery connected at the DC output side of the power converter.

22. A power conversion system according to claim 21, wherein the DC output voltage of the power converter is controlled in accordance with a current flowing through the battery current.

23. A power conversion system according to claim 21, further comprising means inserted between the power converter and the battery for preventing a reverse flow of a current from the battery of the power converter.

24. A power conversion system according to claim 21, further comprising means for limiting the DC output voltage of the power converter within a predetermined range.

25. A power conversion system according to claim 21, further comprising a DC filter circuit inserted between the power converter and the load device.

26. A power conversion system according to claim 25, further comprising a DC filter circuit inserted between the power converter and the load device.

27. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, a battery connected in parallel to the load device, a DC filter circuit including a capacitor connected in parallel to the DC output side of the power converter and a reactor connected in series to the capacitor and the load device, means for preventing a reverse flow of a current from the battery to the power converter, means for limiting an input current of the power converter in accordance with a signal relating to one of the voltage and frequency of the AC power supply, and means for limiting a component of an input voltage of the power converter in phase with the voltage of the power supply to a predetermined value, means for limiting a DC output voltage of the power converter in accordance with a current flowing through the battery, and means for limiting the DC output voltage of the power converter within a predetermined range.

28. A power conversion system comprising a power converter for converting an AC signal of an AC power supply having variable frequency and variable voltage into a DC signal, means for controlling turning-on and off of switching elements of the power converter, a load device connected to a DC output side of the power converter, voltage control means for controlling a DC output voltage of the power converter to a predetermined value, and means for increasing a reactive power of the power supply and setting an effective power of the power supply to a predetermined value.