# US 9,751,409 B2 · Electric automobile

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- Number: US 9,751,409 B2
- Document ID: US9751409B2
- Status: Granted
- Kind: B2
- Application number: 14/587,240
- Filed: 2014-12-31
- Published: 2015-04-30
- Granted: 2017-09-05
- Earliest claimed: 2011-02-25
- Assignees: Ntn Corporation
- Applicants: Ntn Corporation
- Inventors: Takayoshi Ozaki
- Web page: https://patentgrep.com/patent/US9751409B2

## CPC

- B60L 3/06: Limiting the traction current under mechanical overload conditions
- B60K 7/0007: {the motor being electric}
- B60L 1/003: {to auxiliary motors, e.g. for pumps, compressors}
- B60L 3/003: {relating to inverters}
- B60L 3/0061: {relating to electrical machines}
- B60L 3/12: Recording operating variables {; Monitoring of operating variables}
- B60L 15/025: {using field orientation; Vector control; Direct Torque Control [DTC]}
- B60L 15/2009: {for braking}
- B60L 15/2036: {Electric differentials, e.g. for supporting steering vehicles}
- B60L 15/2054: {by controlling transmissions or clutches}
- B60L 50/51: characterised by AC-motors
- B60L 58/12: responding to state of charge [SoC]
- H02P 6/28: Arrangements for controlling current (H02P6/10 takes precedence)
- H02P 29/032: Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
- H02P 29/64: Controlling or determining the temperature of the winding
- B60L 2220/14: Synchronous machines
- B60L 2220/46: Wheel motors, i.e. motor connected to only one wheel
- B60L 2220/50: Structural details of electrical machines
- B60L 2240/12: Speed
- B60L 2240/24: Steering angle
- B60L 2240/34: Cabin temperature
- B60L 2240/36: Temperature of vehicle components or parts
- B60L 2240/421: Speed
- B60L 2240/423: Torque
- B60L 2240/425: Temperature
- B60L 2240/429: Current
- B60L 2240/461: Speed
- B60L 2250/16: by display
- B60L 2250/26: by pedal actuation
- B60L 2260/28: Four wheel or all wheel drive
- B60L 2270/145: Structure borne vibrations
- Y02T 10/64: Electric machine technologies in electromobility
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- Y02T 10/72: Electric energy management in electromobility
- 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
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An electric vehicle includes a motor unit configured to drive a wheel, the motor unit including motor coils; a control system including an inverter; a temperature sensor configured to sense temperature of the motor coils or the inverter; and a limiter configured to, if the temperature sensed by the temperature sensor is equal to or greater than a motor coils temperature threshold, reduce a motor current of the motor unit until a derivative dTmc/dt of the sensed temperature with time drops to zero or below, or to, if the temperature sensed by the temperature sensor is equal to or greater than an inverter temperature threshold, limit a current command to the inverter until a derivative dTic/dt of the sensed temperature with time drops to zero or below. The limiter is further configured to stop reducing a motor current of the motor or limiting the current command to the inverter.

## Claims

### Claim 1

An electric vehicle comprising:
a motor unit configured to drive a wheel, the motor unit including motor coils;
a control system that controls the motor unit, the control system including an inverter;
a temperature sensor that is associated with the motor coils of the motor unit and is configured to sense temperature Tmc of the motor coils or a temperature sensor that is associated with the inverter and is configured to sense temperature Tic of the inverter; and
a limiter configured to, if the temperature Tmc sensed by the temperature sensor is equal to or greater than a motor coils temperature threshold, reduce a motor current of the motor unit, or to, if the temperature Tic sensed by the temperature sensor is equal to or greater than an inverter temperature threshold, reduce a current command value to the inverter,
the limiter being further configured to, upon detecting the sign that the temperature Tmc or Tic has started to drop, stop reducing a motor current of the motor or reducing the current command value to the inverter.

### Claim 2 (depends on 1)

The electric vehicle as claimed in claim 1, wherein the control system includes an electronic control unit (ECU) configured to perform general control of the vehicle and also includes an inverter unit, the inverter unit including a power circuitry which includes the inverter and also including a motor control circuitry configured to control at least the power circuitry in accordance with control from the ECU; and
wherein the inverter is configured to convert a DC power from a battery unit into an AC power used to drive the motor unit.

### Claim 3 (depends on 2)

The electric vehicle as claimed in claim 2, wherein the motor control circuitry includes the limiter; and
wherein the limiter includes a determiner configured to determine if the temperature sensed by the temperature sensor exceeds the motor coils temperature threshold or the inverter temperature threshold and also includes a controller configured to send to the power circuitry, if it is determined that the sensed temperature exceeds the motor coils temperature threshold or the inverter temperature threshold, a command that reduces the motor current of the motor unit or a command that reduces the current command value to the inverter.

### Claim 4 (depends on 3)

The electric vehicle as claimed in claim 3, wherein the inverter unit includes an abnormalities notifier configured to send to the ECU a notification of abnormalities of the motor unit if the determiner determines that the sensed temperature exceeds the motor coils temperature threshold or a notification of abnormalities of the inverter if the determiner determines that the sensed temperature exceeds the inverter temperature threshold.

### Claim 5 (depends on 1)

The electric vehicle as claimed in claim 1, further comprising:
a wheel bearing unit; and
a reducer unit;
wherein the motor unit, together with the wheel bearing unit and the reducer unit, forms an in-wheel motor drive system that is partly or entirely disposed within the wheel.

### Claim 6 (depends on 1)

The electric vehicle as claimed in claim 1, further comprising:
a reducer unit configured to produce rotation with a speed that is reduced with respect to that of rotation of the motor unit,
wherein the reducer unit comprises a cycloidal reducer.