# US 8,786,238 B2 · Drive system for rotating electric machine

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- Number: US 8,786,238 B2
- Document ID: US8786238B2
- Status: Granted
- Kind: B2
- Application number: 13/558,130
- Filed: 2012-07-25
- Published: 2013-02-28
- Granted: 2014-07-22
- Earliest claimed: 2011-08-22
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Hichirosai Oyobe; Shinjiro Ashida
- Inventors: Hichirosai Oyobe; Shinjiro Ashida
- Web page: https://patentgrep.com/patent/US8786238B2

## CPC

- H02P 3/22: by short-circuit or resistive braking
- B60L 3/0007: {Measures or means for preventing or attenuating collisions}
- B60L 3/04: Cutting off the power supply under fault conditions (protective devices and circuit arrangements in general H01H; H02H)
- B60L 2210/42: Voltage source inverters
- B60L 2240/421: Speed
- B60L 2240/526: Operating parameters
- B60L 2240/529: Current
- Y02T 10/64: Electric machine technologies in electromobility
- Y02T 10/72: Electric energy management in electromobility
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A MG drive computer switches off system relays when a collision or a possibility of collision is detected. The computer also executes the revolution speed reduction control for reducing the revolution speed of a rotating electric machine and the discharge control for discharging a smoothing capacitor. In the revolution speed reduction control, the second control for switching on switching elements of three phases of an upper arm or lower arm of an inverter and switching off all other switching elements is performed when the revolution speed of the rotating electric machine is equal to or less than a second threshold. When the revolution speed is higher than the second threshold, the first control for switching on a switching element of one phase of the upper arm or lower arm and switching off other switching elements is performed.

## Claims

### Claim 1

A drive system for a rotating electric machine that functions as a running drive source for a vehicle, comprising:
a collision detection unit that detects a collision or a possibility of collision of the vehicle;
an inverter that converts direct current power supplied from a direct current supply into alternating current power and outputs the alternating current power to the rotating electric machine;
a smoothing capacitor that smoothes a voltage between terminals of the inverter; and
a controller that performs a discharge control for controlling the inverter, wherein
when the collision or possibility of collision is detected, the controller cuts off a power output from the direct current supply, performs a revolution speed reduction control for reducing a revolution speed of the rotating electric machine to a value equal to or less than a predetermined first threshold, and then discharges electric charges accumulated in the smoothing capacitor, and wherein
the controller performs a first control for switching on a switching element of one arm among an upper arm and a lower arm of the inverter for only one phase and switching off all other switching elements when the revolution speed of the rotating electric machine exceeds a second threshold that is higher than the first threshold in the revolution speed reduction control.

### Claim 2 (depends on 1)

The drive system for a rotating electric machine according to claim 1, wherein the controller performs a second control for switching off the switching elements of one arm among the upper arm and the lower arm of the inverter for all of three phases and switching on the switching elements of the other arm for all of the three phases when the revolution speed of the rotating electric machine is equal to or lower than the second threshold and higher than the first threshold in the revolution speed reduction control.

### Claim 3 (depends on 1)

The drive system for a rotating electric machine according to claim 1, wherein the second threshold is a revolution speed at which a drag torque generated by the first control is equal to a drag torque generated by the second control.

### Claim 4 (depends on 1)

The drive system for a rotating electric machine according to claim 1, wherein the second threshold is a revolution speed at which a drag torque generated by the first control is greater than a drag torque generated by the second control.