Power conversion device

Patent metadata

Field	Value
Publication number	US-11283386-B2
Application number	US-201816769996-A
Country	US
Kind code	B2
Filing date	Nov 15, 2018
Priority date	Dec 22, 2017
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

There is provided a power conversion device capable of eliminating a disadvantage of a sharp temperature rise in a switching element by using a discontinuous modulation method. The power conversion device includes a phase voltage command operation unit 33 which calculates a sinusoidal modulation voltage command value to be applied to a motor 8, an inter-line modulation operation unit 34 which, based on the sinusoidal modulation voltage command value, calculates a discontinuous modulation voltage command value for allowing an ON/OFF state of a switching element of one phase of a three-phase inverter circuit 28 to be fixed, and modulating ON/OFF states of switching elements of other two phases, and a PWM signal generation unit 36. The inter-line modulation operation unit sets a switching density of the switching element of at least one phase to a value different from that of the other phase.

First claim

The invention claimed is:

1. A power conversion device comprising:
a three-phase inverter circuit which drives a motor;
a phase voltage command operation unit which calculates a sinusoidal modulation voltage command value to be applied to the motor;
an inter-line modulation operation unit which calculates a discontinuous modulation voltage command value fixing ON/OFF states of predetermined switching elements of one phase of the three-phase inverter circuit and modulating ON/OFF states of switching elements of other two phases of the three-phase inverter circuit, based on the sinusoidal modulation voltage command value; and
a PWM signal generation unit which generates a PWM signal PWM-controlling the three-phase inverter circuit, based on the discontinuous modulation voltage command value,
wherein the inter-line modulation operation unit is configured to set a switching density of the switching elements of at least one phase of the three-phase inverter circuit to a value different from that of the switching elements of the other two phases,
wherein the inter-line modulation operation unit changes the switching density according to a temperature of the switching elements of the at least one phase, and
wherein the inter-line modulation operation unit reduces the switching density of the switching elements of the at least one phase whose temperature is higher than that of the switching elements of the other two phases.

2. The power conversion device according to claim 1 , wherein the inter-line modulation operation unit compares the sinusoidal modulation voltage command values of each phase of the three-phase inverter circuit and fixes the ON/OFF state of the switching elements of the phase whose absolute value becomes maximum, and
wherein when the sinusoidal modulation voltage command values of each phase of the three-phase inverter circuit are compared, the inter-line modulation operation unit multiplies the sinusoidal modulation voltage command values of phases of the three phase inverter circuit having at least a switching density set to a value different from other phases of the three phase inverter circuit by a predetermined bias value, and thereafter compares the sinusoidal modulation voltage command values of each phase of the three phase inverter circuit.

3. The power conversion device according to claim 2 , wherein the inter-line modulation operation unit sets the bias value to a value which is larger than 1 and less than or equal to 2.

4. The power conversion device according to claim 3 , wherein when the switching densities of the switching elements of each phase of the three-phase inverter circuit are made the same, the inter-line modulation operation unit sets the bias value to 1 or does not multiply the sinusoidal modulation voltage command value of each phase of the three-phase inverter circuit by the bias value when comparing the sinusoidal modulation voltage command values of each phase of the three-phase inverter circuit.

5. The power conversion device according to claim 3 , wherein each of the switching elements of each phase of the three-phase inverter circuit is disposed in a heat exchange relation with a refrigerant sucked into an electric compressor.

6. The power conversion device according to claim 2 , wherein when the switching densities of the switching elements of each phase of the three-phase inverter circuit are made the same, the inter-line modulation operation unit sets the bias value to 1 or does not multiply the sinusoidal modulation voltage command value of each phase of the three-phase inverter circuit by the bias value when comparing the sinusoidal modulation voltage command values of each phase of the three-phase inverter circuit.

7. The power conversion device according to claim 6 , wherein each of the switching elements of each phase of the three-phase inverter circuit is disposed in a heat exchange relation with a refrigerant sucked into an electric compressor.

8. The power conversion device according to claim 2 , wherein each of the switching elements of each phase of the three-phase inverter circuit is disposed in a heat exchange relation with a refrigerant sucked into an electric compressor.

9. The power conversion device according to claim 1 , wherein each of the switching elements of each phase of the three-phase inverter circuit is disposed in a heat exchange relation with a refrigerant sucked into an electric compressor.

Assignees

• Sanden Holdings Corp

Inventors

• Kashihara Tatsuki
• SAIGUSA Takahiro

Classifications

• B60H1/3222

  characterised by the compressor driving arrangements, e.g. clutches, transmissions or multiple drives (B60H1/3208, B60H1/3226 take precedence) · CPC title

• H02P29/68

  based on the temperature of a drive component or a semiconductor component · CPC title

• H02M7/5395

  by pulse-width modulation · CPC title

• H02P27/08 Primary

  with pulse width modulation · CPC title

• H02M7/53871 Primary

  with automatic control of output voltage or current · CPC title