POWER CONVERTER

• US 20110019442A1
• Filed: 07/20/2010
• Published: 01/27/2011
• Est. Priority Date: 07/21/2009
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: INOUE, Shigenori, KATOH, Shuji, YAMADA, Yoichiro
• Granted Patent: US 8,711,586 B2
• Time in Patent Office: Days
• US Class Current: 363/44
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 1/0043 Converters switched with a phase shift, i.e. interleaved non-isolated DC/DC converters H02M3/1586
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output
• CPC Class Codes: H02M 7/219 in a bridge configuration
• CPC Class Codes: H02M 7/483 Converters with outputs that each can have more than two voltages levels
• CPC Class Codes: H02M 7/4835 comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
• CPC Class Codes: H02M 7/5395 by pulse-width modulation

Abstract

The noise generated from a power converter is suppressed by increasing the noise frequency to a level not lower than the maximum frequency of the human audible range. To obtain the frequency of an output current harmonic component as a noise source which has exceeded the maximum frequency of the human audible range, it is adequate to determine that the frequency of a driving carrier wave for the individual converter cells in the power converter, in which the phases of the carrier wave for the converter cells are mutually shifted by a given value between the converter cells, meets the following equation.

f _carrier ≧f _{audibility — max} ÷N

Claims

1. A power converter provided with a plurality of arms which are comprised of a plurality of converter cells connected in cascade, comprising:

means for mutually shifting phases of carrier waves of the converter cells by a prescribed value between the converter cells in the arms; and

means for operating frequencies of the carrier waves of the converter cells in a state larger than a value which is obtained by dividing a maximum frequency of a human audible frequency band by the number of the converter cells in the arms.

2. The power converter according to claim 1, comprising:

interconnected reactors;

buffer reactors;

arms configured of a plurality of converter cells connected in cascade;

a control device for controlling the converter cells; and

a signal line for transmitting a control signal from the control device to the converter cells, wherein;

the arms are arranged on positive and negative sides of each of three phases.

3. The power converter according to claim 1, wherein the converter cell is provided with:

a capacitor for storing electric power;

fuses for cutting off the electric current in case of overcurrent;

a cell configured with a plurality of switching elements connected in a half bridge state;

a converter cell control circuit for outputting a control signal for the switching elements;

a gate driver for applying a voltage to the switching elements according to the control signal outputted from the converter cell control circuit;

a gate power supply for supplying necessary electric power to the gate driver; and

a self-feeding supply for supplying necessary electric power to the gate power supply and the converter cell control circuit.

4. The power converter according to claim 1, comprising:

a synchronous signal generator for generating a synchronous signal at every given time;

a carrier wave generator for generating a carrier wave for the converter cell after having as an input the synchronous signal which is outputted from the synchronous signal generator; and

an individual-phase target voltage generator for generating a target voltage of each of three phases which are mutually shifted by ⅓

cycle.

5. The power converter according to claim 1, wherein the converter cell control circuit is provided with a comparator which outputs to the gate driver an ON/OFF signal for the switching elements according to a magnitude relation between the target voltage and the carrier wave for the converter cell.

6. The power converter according to claim 1, wherein the converter cell is provided with:

a capacitor for storing electric power;

fuses for cutting off the electric current in case of overcurrent;

a cell configured with a first leg and a second leg, which are configured with a plurality of switching elements connected in series, connected in a full bridge state;

a converter cell control circuit for outputting a control signal for the switching elements;

a gate driver for applying a voltage to the switching elements according to the control signal outputted from the converter cell control circuit;

a gate power supply for supplying necessary electric power to the gate driver; and

a self-feeding supply for supplying necessary electric power to the gate power supply and the converter cell control circuit.

7. The power converter according to claim 1, comprising:

a synchronous signal generator for generating a synchronous signal at every given time;

a carrier wave generator for generating a carrier wave for the converter cell after having as an input the synchronous signal which is outputted from the synchronous signal generator;

a first individual-phase target voltage generator for generating a target voltage of each of three phases which are mutually shifted by ⅓

cycle; and

a second individual-phase target voltage generator for outputting a target voltage with the phase shifted by ½

cycle with respect to the target voltage which is outputted from the first individual-phase target voltage generator.

8. The power converter according to claim 1, wherein the converter cell control circuit is provided with:

a first comparator for generating an ON/OFF signal for the switching elements configuring the first leg according to the magnitude relation between the target voltage outputted from the first individual-phase target voltage generator and the carrier wave for the converter cell outputted from the carrier wave generator; and

a second comparator for generating an ON/OFF signal for the switching elements configuring the second leg according to the magnitude relation between the target voltage outputted from the second individual-phase target voltage generator and the carrier wave for the converter cell outputted from the carrier wave generator.

9. The power converter according to claim 1, comprising:

a synchronous signal generator for generating a synchronous signal at every given time; and

an individual-phase target voltage generator for generating a target voltage of each of three phases which are mutually shifted by ⅓

cycle.

10. The power converter according to claim 1, wherein the converter cell control circuit is provided with:

a carrier wave generator for outputting a carrier wave for the converter cell after having as an input the synchronous signal which is outputted from the synchronous signal generator; and

a comparator for generating an ON/OFF signal for the switching elements according to the magnitude relation between the carrier wave for the converter cell outputted from the carrier wave generator and the target voltage outputted from the individual-phase target voltage generator.

11. The power converter according to claim 1, wherein the control device is provided with:

a synchronous signal generator for generating a synchronous signal at every given time;

a first individual-phase target voltage generator for generating a target voltage of each of three phases which are mutually shifted by ⅓

cycle; and

a second individual-phase target voltage generator for outputting a target voltage with the phase shifted by ½

cycle with respect to the target voltage which is outputted from the first individual-phase target voltage generator.

12. The power converter according to claim 1, wherein the converter cell control circuit is provided with:

a carrier wave generator for outputting a carrier wave for the converter cell after having as an input the synchronous signal which is outputted from the synchronous signal generator;

a first comparator for generating an ON/OFF signal for the switching elements configuring the first cell according to the magnitude relation between the target voltage outputted from the first individual-phase target voltage generator and the carrier wave for the converter cell outputted from the carrier wave generator; and

a second comparator for generating an ON/OFF signal for the switching elements configuring the second cell according to the magnitude relation between the target voltage outputted from the second individual-phase target voltage generator and the carrier wave for the converter cell outputted from the carrier wave generator.

13. The power converter according to claim 1, wherein the control device is provided with:

an individual-phase target voltage generator for generating a target voltage of each of three phases which are mutually shifted by ⅓

cycle;

a synchronous signal generator for generating a synchronous signal at every given time;

a carrier wave generator for generating a carrier wave for the converter cell after having as an input the synchronous signal which is outputted from the synchronous signal generator; and

a comparator which outputs to the converter cell control circuit an ON/OFF signal for the switching element according to a magnitude relation between the target voltage and the carrier wave for the converter cell.

14. The power converter according to claim 1, wherein the control device is provided with:

a first individual-phase target voltage generator for generating a target voltage of each of three phases which are mutually shifted by ⅓

cycle;

a second individual-phase target voltage generator for outputting a target voltage with the phase shifted by ½

cycle with respect to the target voltage which is outputted from the first individual-phase target voltage generator;

a synchronous signal generator for generating a synchronous signal at every given time;

a carrier wave generator for generating a carrier wave for the converter cell after having as an input the synchronous signal which is outputted from the synchronous signal generator;

a first comparator for generating an ON/OFF signal for the switching elements configuring a first leg according to the magnitude relation between the target voltage outputted from the first individual-phase target voltage generator and the carrier wave outputted from the carrier wave generator; and

a second comparator for generating an ON/OFF signal for the switching elements configuring a second leg according to the magnitude relation between the target voltage outputted from the second individual-phase target voltage generator and the carrier wave outputted from the carrier wave generator.

15. The power converter according to claim 1, comprising:

a transformer;

a buffer reactor;

arms configured of a plurality of converter cells connected in cascade;

a control device for controlling the converter cells; and

a signal line for transmitting a control signal from the control device to the converter cells, wherein;

the arms are arranged on each of three phases.

16. The power converter according to claim 2, wherein the control signal between the control device and the converter cell control circuit is transmitted wirelessly instead of through the signal line.

17. The power converter according to claim 15, wherein the control signal between the control device and the converter cell control circuit is transmitted wirelessly instead of through the signal line.