# US 2017/0282968 A1 · Motor control device, electric power steering device and inverter system failure detection method

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- Number: US 2017/0282968 A1
- Document ID: US20170282968A1
- Status: Published application
- Kind: A1
- Application number: 15/510,905
- Filed: 2014-11-04
- Published: 2017-10-05
- Earliest claimed: 2014-11-04
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Isao KEZOBO; Yoshihiko KIMPARA; Shunsuke NAKAJIMA
- Web page: https://patentgrep.com/patent/US20170282968A1

## CPC

- B62D 5/0484: {for reaction to failures, e.g. limp home}
- B62D 5/046: {Controlling the motor}
- G01R 31/00: Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere ({measuring superconductive properties G01R33/1238;} testing line transmission systems H04B3/46; testing or measuring semiconductors or solid state devices during manufacture {H10P74/00})
- G01R 31/006: {on road vehicles, e.g. automobiles or trucks (testing of ignition installations peculiar to internal combustion engines F02P17/00)}
- G01R 31/343: {in operation}
- G01R 31/42: AC power supplies
- H02P 6/12: Monitoring commutation; Providing indication of commutation failure
- H02P 6/14: Electronic commutators
- H02P 27/06: using DC to AC converters or inverters (H02P27/05 takes precedence)
- H02P 29/024: Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load
- H02P 29/0241: {the fault being an overvoltage}
- B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## 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.

## Claims

### 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 1)

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.

### Claim 5 (depends on 4)

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.

### Claim 6 (depends on 5)

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.

### Claim 7 (depends on 1)

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.

### Claim 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.