Motor control device, electric power steering device and inverter system failure detection method

Patent metadata

Field	Value
Publication number	US-2017282968-A1
Application number	US-201415510905-A
Country	US
Kind code	A1
Filing date	Nov 4, 2014
Priority date	Nov 4, 2014
Publication date	Oct 5, 2017
Grant date	—

Abstract

An inverter system failure is detected on the basis of the currents of respective phases detected by a current detection unit when carrying out switching control in accordance with a first drive mode in which all switching elements on a lower-side arm are switched on and all switching elements on an upper-side arm are switched off, and the currents of respective phases detected by the current detection unit when carrying out switching control in accordance with a second drive mode in which all of the switching elements on the upper-side arm are switched on and all of the switching elements on the lower-side arm are switched off.

First claim

1 . A motor control device which controls driving of a motor having multiple-phase windings by using detection values of currents flowing in respective phases of the motor, the motor control device comprising:
an inverter in which a plurality of circuits, each having switching elements respectively on an upper-side arm and a lower-side arm, are connected in parallel, and which supplies power to the motor; a motor control unit which controls driving of the motor by controlling the inverter; and a current detection unit which is connected to each of the switching elements on the lower-side arm and which detects the current in each of the phases, wherein the motor control unit has: a first drive mode in which switching control is carried out to switch on all of the switching elements on the lower-side arm, and to switch off all of the switching elements on the upper-side arm; and a second drive mode in which switching control is carried out to switch on all of the switching elements on the upper-side arm, and to switch off all of the switching elements on the lower-side arm, and the motor control unit: carries out a first failure determination for determining whether or not the sum of the currents of the respective phases detected as a first failure detection current by the current detection unit is within a previously established first threshold value range, when switching control is carried out in accordance with the first drive mode; carries out a second failure determination for determining whether or not each of the currents of the respective phases detected as a second failure detection current by the current detection unit is within a previously established second threshold value range, when switching control is carried out in accordance with the second drive mode; and detects an inverter system failure in accordance with the determination results of the first failure determination and the second failure determination.

2 . The motor control device according to claim 1 , wherein the motor control unit determines that, as the inverter system failure, a shorting failure of the switching elements on the lower-side arm has occurred, when determining, in the first failure determination, that the sum of the currents of the respective phases detected as the first failure detection current is within the first threshold value range, and when determining, in the second failure determination, that each of the currents of the respective phases detected as the second failure detection current is not within the second threshold value range.

3 . The motor control device according to claim 1 , wherein the motor control unit determines that, as the inverter system failure, a shorting failure of the switching elements on the upper-side arm has occurred, when determining, in the first failure determination, that the sum of the currents of the respective phases detected as the first failure detection current is not within the first threshold value range, and when determining, in the second failure determination, that each of the currents of the respective phases detected as the second failure detection current is within the second threshold value range.

4 . The motor control device according to claim 1 , wherein the motor control unit determines that, as the inverter system failure, a current sensor system failure has occurred, when determining, in the first failure determination, that the sum of the currents of the respective phases detected as the first failure detection current is not within the first threshold value range, and when determining, in the second failure determination, that each of the currents of the respective phases detected as the second failure detection current is not within the second threshold value range.

5 . The motor control device according to claim 4 , wherein the motor control unit identifies, as a current detection abnormality phase, a phase in which a current that is not within a previously established third threshold value range, among the currents of the respective phases detected as the second failure detection current, is detected, or a phase in which a current included in a previously established fourth threshold value range, among the currents of the respective phases detected as the first failure detection current, is detected.

6 . The motor control device according to claim 5 , wherein when there is one identified current detection abnormality phase, the motor control unit controls driving of the motor by using the currents of normal phases, which are phases other than the current detection abnormality phase among the respective phases detected by the current detection unit.

7 . An electric power steering device comprising:
the motor control device according to claim 1 ; and a motor having multiple-phase windings controlled by the motor control device.

8 . An inverter system failure detection method which is executed by a motor control device including an inverter in which a plurality of circuits, each having switching elements respectively on an upper-side arm and a lower-side arm, are connected in parallel, and which supplies power to a motor, and a current detection unit which is connected to each of the switching elements on the lower-side arm and which detects currents in respective phases of the motor, the method comprising:
a step of carrying out first failure determination for determining whether or not the sum of the currents of the respective phases detected as a first failure detection current by the current detection unit is within a first threshold value range, when all of the switching elements on the lower-side arm are switched on and all of the switching elements on the upper-side arm are switched off; a step of carrying out second failure determination for determining whether or not each of the currents of the respective phases detected as a second failure detection current by the current detection unit is within a second threshold value range, when all of the switching elements on the upper-side arm are switched on and all of the switching elements on the lower-side arm are switched off; and a step of detecting an inverter system failure in accordance with the determination results of the first failure determination and the second failure determination.

Assignees

• Mitsubishi Electric Corp

Inventors

• Kezobo Isao
• Kimpara Yoshihiko
• Nakajima Shunsuke

Classifications

• H02P6/14

  Electronic commutators · CPC title

• G01R31/343

  in operation · CPC title

• G01R31/006 Primary

  on road vehicles, e.g. automobiles or trucks (testing of ignition installations peculiar to internal combustion engines F02P17/00) · CPC title

• B62D5/0484 Primary

  for reaction to failures, e.g. limp home · CPC title

• H02P6/12

  Monitoring commutation; Providing indication of commutation failure · CPC title