Power conversion device for a rotary electric machine

Patent metadata

Field	Value
Publication number	US-8963479-B2
Application number	US-201113311592-A
Country	US
Kind code	B2
Filing date	Dec 6, 2011
Priority date	Dec 7, 2010
Publication date	Feb 24, 2015
Grant date	Feb 24, 2015

Abstract

A power conversion device includes an inverter unit and a control unit. The inverter unit includes high SWs and low SWs for each phase of coils of a motor. The control unit, in a case that the on-time of the high SWs and the low SWs is shorter than a predetermined time determined based on a dead time, changes an output voltage average value such that the on-time of the high SWs or the on-time of the low SWs becomes longer than the predetermined time. The voltage use rate can be improved without disposing a special circuit, and distortion of inter-line voltages or distortion of currents can be suppressed.

First claim

What is claimed is:

1. A power conversion device that controls power supplied to coils corresponding to each phase of a rotary electric machine through pulse width modulation, the power conversion device comprising:
an inverter unit that includes high electric potential-side switching devices arranged on a high electric potential-side and low electric potential-side switching devices arranged on a low electric potential side in correspondence with each phase of the coils of the rotary electric machine, and the inverter unit includes a current detecting section that detects a current flowing in each phase of the coils of the rotatory electric machine;
a control unit that, in a case where there is a phase at which an on-time of the high electric potential-side switching devices or an on-time of the low electric potential-side switching devices is shorter than a predetermined time, which is determined based on a dead time set to prevent the high electric potential-side switching device and the low electric potential-side switching device corresponding to each phase of the coils from turning on simultaneously, changes an output voltage average value that is an average value of voltages applied to each phase of the coils by controlling switching between ON and OFF of the high electric potential-side switching devices and the low electric potential-side switching devices of all the phases such that the on-time becomes equal to or longer than the dead time,
wherein the control unit calculates an output voltage of the inverter unit defined by a magnitude, which is calculated in accordance with a current command value, the current detected by the current detecting section, and a phase angle, and changes the output voltage average value in a period, in which there is the phase at which the on-time of the high electric potential-side switching devices or the on-time of the low electric potential-side switching devices is less than the dead time, by switching the pulse width modulation between a two-phase modulation and a three-phase modulation based on the magnitude and the phase angle of the output voltage of the inverter unit.

2. The power conversion device according to claim 1 , wherein:
the control unit is configured to perform the pulse width modulation by using a triangular wave comparing method that is based on duty command values and triangular wave command values;
the control unit includes a duty converting section, a modulation section and a shifting section,
the duty converting section calculating duty conversion values having different phases for each phase based on voltage command values applied to the coils of each phase,
the modulation section calculating modulated duty command values acquired by modulating duties that are based on the duty conversion values of each phase calculated by the duty converting section, and
the shifting section calculating shifted duty command values acquired by shifting the modulated duty command values of each phase based on a shifting value that is set such that the on-time is equal to or longer than the predetermined time, in a case where there is a phase at which the on-time of the high electric potential-side switching devices or the low electric potential-side switching devices is shorter than the predetermined time when the high electric potential-side switching devices and the low electric potential-side switching devices are turned on or off based on the modulated duty command values modulated by the modulation section; and
the control unit is configured to control the switching between ON and OFF of the high electric potential-side switching devices and the low electric potential-side switching devices based on the duty command values calculated based on the shifted duty command values.

3. The power conversion device according to claim 1 , wherein:
the control unit is configured to perform the pulse width modulation by using an instantaneous voltage vector selecting method that is based on a command voltage vector; and
the control unit includes a two-phase modulation section and a three-phase modulation section,
the two-phase modulation section controlling switching between ON and OFF of the high electric potential-side switching devices and the low electric potential-side switching devices through the two-phase modulation that is controlled by using one of a first zero-voltage vector in which all the high electric potential-side switching devices are turned on or a second zero-voltage vector in which all the low electric potential-side switching devices are turned on as a zero-voltage vector, and
the three-phase modulation section controlling switching between ON and OFF of the high electric potential-side switching devices and the low electric potential-side switching devices by switching to the three-phase modulation that is controlled by using the first zero-voltage vector and the second zero-voltage vector such that the on-time in which the high electric potential-side switching devices or the low electric potential-side switching devices are turned on is equal to or longer than the predetermined time, in a case where a basic vector is less than a determination value set based on the dead time when the command vector is decomposed into the basic vector.

4. The power conversion device according to claim 2 , wherein:
the control unit further includes a dead-time compensating section and a correction section,
the dead-time compensating section calculating compensated duty command values by changing the duty based on a dead-time compensating value that is a value based on the dead time to eliminate a change amount of voltages applied to the coils in accordance with a polarity of currents conducted in the coils due to an influence of the dead time, and
the correction section correcting the duties of phases other than a near-limit phase, in a case where there is the near-limit phase that is a phase at which the duty is within a predetermined range from an high limit value of the duty or a low limit value of the duty.

5. The power conversion device according to claim 2 , wherein:
the modulation section adds third harmonics to the duties of all the phases.

6. The power conversion device according to claim 2 , wherein:
the modulation section subtracts an average value of the duty of a largest duty phase and the duty of a smallest duty phase from the duties of all the phases.

7. A power conversion device that controls power supplied to coils corresponding to each phase of a rotary electric machine through pulse width modulation, the power conversion device comprising:
an inverter unit that includes high electric potential-side switching devices arranged on a high electric potential-side and low electric potential-side switching devices arranged on a low electric potential side in correspondence with each phase of the coils of the rotary electric machine; and
a control unit that, in a case where there is a phase at which an on-time of the high electric potential-side switching devices or an on-time of the low electric potential-side switching devices is shorter than a predetermined time, which is determined based on a dead time set to prevent the high electric potential-side switching device and the low electric potential-side switching device corresponding to each phase of the coils from turning on simultaneously, changes an output voltage average value that is an average value of voltages applied to each phase of the coils by controlling switching between ON and OFF of the high electric potential-side switching devices and the low electric potential-side switching devices of all the phases such that the on-time becomes equal to or longer than the predetermined time, wherein
the control unit is configured to perform the pulse wi

Assignees

• Suzuki Takashi
• Shiomi Kazutoshi
• Hiruma Atsuyuki
• Hayakawa Shingo
• Denso Corp

Inventors

• Suzuki Takashi
• Shiomi Kazutoshi
• Hiruma Atsuyuki
• Hayakawa Shingo

Classifications

• H02P27/085 Primary

  wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency · CPC title

• H02M2001/385

  Electricity · mapped topic

• H02M1/385

  with means for correcting output voltage deviations introduced by the dead time · CPC title