Power conversion device

Patent metadata

Field	Value
Publication number	US-9350284-B2
Application number	US-201214355452-A
Country	US
Kind code	B2
Filing date	Oct 22, 2012
Priority date	Nov 1, 2011
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

In a system for driving an electric motor by an engine generator, there is a possibility that oscillation and d-axis current are increased. In an engine generator system, a power converter ( 105 ) controls a generator ( 104 ) so that the phase of an oscillating component included in the d-axis current in the rotor magnetic flux direction of the generator ( 104 ) advances by 90 degrees or more with respect to the phase of an oscillating component of the identical frequency included in the rotating electric angular frequency of the generator ( 104 ), and further using q-axis voltage adjusting device ( 118 ) so that the phase of an oscillating component included in the q-axis current advances by 90 degrees or more with respect to the phase of an oscillating component of the identical frequency included in the rotating electric angular frequency of the generator ( 104 ).

First claim

The invention claimed is:

1. A power conversion device for an engine generator system,
the engine generator system comprising:
a generator;
an engine for driving the generator;
a PWM signal controller for performing pulse width modulation on a three-phase voltage command signal via a carrier signal, the three-phase voltage command signal being in accordance with current flowing through the generator;
a power conversion device driven by a pulse width modulated gate signal;
an electric motor; and
a power converter for driving the electric motor,
wherein the power conversion device regulates a voltage command on a d-axis in the magnetic flux direction of a rotor in the generator so that the phase of an oscillating component included in current of the d-axis in the generator advances 90 degrees or more with respect to the phase of an oscillating component of identical frequency included in a rotating electric angular frequency of the generator, and further regulates a voltage command on a q-axis perpendicular to the d-axis so that the phase of an oscillating component included in current of the q-axis advances 90 degrees or more with respect to the phase of an oscillating component of the identical frequency included in the rotating electric angular frequency of the generator.

2. The power conversion device according to claim 1 ,
wherein, in a case where the points of intersection of a mean value of a waveform representing an oscillating component in the rotating electric angular frequency and the waveform of the oscillating component are specified as zero points, and the points of intersection of a mean value of a waveform representing oscillating components of an oscillation frequency in current of the q-axis as well as current of the d-axis and the waveform of the oscillating components are specified as zero points, the power conversion device regulates a voltage command so that zero points acquired from a waveform of oscillating components in current of the q-axis and current of the d-axis advance by 90 degrees or more with respect to zero points acquired from a waveform of an oscillating component in the rotating electric angular frequency.

3. The power conversion device according to claim 2 ,
wherein means for regulating the voltage command comprises any one of: proportion; proportion and first-order lag; proportion and differentiation; proportion, first-order lag and inexact differentiation; proportion and inexact differentiation; and proportion, differentiation and inexact differentiation.

4. The power conversion device according to claim 1 ,
wherein, specifying a distance between the peak values of a waveform of an oscillating component in the rotating electric angular frequency as 180 degrees and a distance between the peak values of a waveform of oscillating components in current of the q-axis and current of the d-axis as 180 degrees, the power conversion device regulates a voltage command so that a maximum peak value of oscillating components in current of the q-axis and current of the d-axis advances by 90 degrees or more with respect to a maximum peak value acquired from a waveform of an oscillating component in the rotating electric angular frequency.

5. The power conversion device according to claim 4 ,
wherein means for regulating the voltage command comprises any one of: proportion; proportion and first-order lag; proportion and differentiation; proportion, first-order lag and inexact differentiation; proportion and inexact differentiation; and proportion, differentiation and inexact differentiation.

6. A power conversion device for an electric motor driving system,
the electric motor driving system comprising:
an electric motor;
a PWM signal controller for performing pulse width modulation on a three-phase voltage command signal via a carrier signal, the three-phase voltage command signal being in accordance with current flowing through the electric motor; and
a power conversion device driven by a pulse width modulated gate signal,
wherein the power conversion device regulates a voltage command on a d-axis in the magnetic flux direction of a rotor in the electric motor so that the phase of an oscillating component included in current of the d-axis in the electric motor advances 90 degrees or more with respect to the phase of an oscillating component of identical frequency included in a rotating electric angular frequency of the electric motor, and further regulates a voltage command on a q-axis perpendicular to the d-axis so that the phase of an oscillating component included in current of the q-axis advances 90 degrees or more with respect to the phase of an oscillating component of the identical frequency included in the rotating electric angular frequency of the electric motor.

Assignees

• Hitachi Ltd

Inventors

• Sakai Toshifumi
• Nagata Koichiro
• Iwaji Yoshitaka
• Shimada Motomi

Classifications

• H02P9/102

  for limiting effects of transients · CPC title

• H02P21/05 Primary

  specially adapted for damping motor oscillations, e.g. for reducing hunting · CPC title

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• H02P23/04 Primary

  specially adapted for damping motor oscillations, e.g. for reducing hunting · CPC title

• H02P21/22

  Current control, e.g. using a current control loop · CPC title