In-wheel motor system

• US 10,421,351 B2
• Filed: 02/16/2015
• Issued: 09/24/2019
• Est. Priority Date: 03/07/2014
• Status: Active Grant

• Current Assignee: NSK Limited, University of Tokyo
• Original Assignee: University of Tokyo
• Inventors: Fujimoto, Hiroshi, Imura, Takehiro, Yamamoto, Gaku, Gunji, Daisuke, Sato, Motoki
• Primary Examiner(s): Gonzalez, Julio C.
• Assistant Examiner(s): Pham, Leda T
• Application Number:
  US15/123,731
• Publication Number:
  US 20170008385A1
• Time in Patent Office: 1,681 Days
• CPC Class Codes: B60K 2007/0038 the motor moving together with the wheel axle
• CPC Class Codes: B60K 2007/0092 the motor axle being coaxial to the wheel axle
• CPC Class Codes: B60K 7/0007 the motor being electric
• CPC Class Codes: B60L 15/007 Physical arrangements or structures of drive train converters specially adapted for the propulsion motors of electric vehicles
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 2210/42 Voltage source inverters
• CPC Class Codes: B60L 2220/44 Wheel Hub motors, i.e. integrated in the wheel hub
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 50/66 Arrangements of batteries
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02K 7/14 Structural association with mechanical loads, e.g. with hand-held machine tools or fans with fan or impeller for cooling the machine H02K9/06
• CPC Class Codes: H02P 27/08 : with pulse width modulation
• CPC Class Codes: H02P 6/14 : Electronic commutators
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/12 : Electric charging stations
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 : Information or communication technologies improving the operation of electric vehicles

Abstract

An in-wheel motor system can drive an in-wheel motor stably, and also allows power feeding from the road surface, even when transmission and reception coils are misaligned. An in-wheel motor system (1) includes a power transmitter (100) that utilizes a resonance phenomenon using a magnetic field. The power transmitter (100) transmits power (P) wirelessly from the vehicle body to an in-wheel motor (10) mounted in a wheel. The in-wheel motor system (1) may also include a communication interface (110) that communicates between the vehicle body and the wheel, and the communication interface (110) may transmit a control signal (CTL) for driving the in-wheel motor.

Claims

1. An in-wheel motor system comprising:

a power transmitter that utilizes a resonance phenomenon using a magnetic field;

a communication interface configured to communicate between a vehicle body and a wheel;

a in-wheel motor;

a motor conversion unit configured to convert a first DC voltage into a motor AC voltage that drives the in-wheel motor during powering;

a wheel side capacitor configured to smooth the first DC voltage during powering;

a wheel side conversion unit configured to convert a first AC voltage from a wheel side coil into the first DC voltage during powering; and

a wheel side controller configured to control, with a first control signal, switching of a switch provided in the wheel side conversion unit;

wherein

the power transmitter comprises;

the wheel side coil, configured to receive wirelessly transmitted power at the wheel side during powering; and

a wheel side resonance capacitor inserted in series between the wheel side conversion unit and the wheel side coil;

the power transmitter transmits power wirelessly from the vehicle body to the in-wheel motor mounted in the wheel;

the communication interface wirelessly transmits a control signal for driving the in-wheel motor; and

the wheel side controller generates the first control signal with the timing at a zero cross point of a current of the wheel side coil as a reference, so as to control the first DC voltage to be constant.

2. The in-wheel motor system of claim 1, wherein the wheel side controller generates the first control signal so that a fundamental power factor of the first AC voltage and the current of the wheel side coil becomes 1.

3. The in-wheel motor system of claim 1, wherein with the first control signal, the wheel side controller adjusts a duration that the first AC voltage is zero.

4. The in-wheel motor system of claim 1, further comprising:

a wheel side current detector configured to detect a current of the wheel side conversion unit;

wherein

the wheel side controller detects a sign change in a current of the wheel side coil with the wheel side current detector and generates the first control signal in accordance with information on the detected sign change.

5. The in-wheel motor system of claim 1, further comprising:

a voltage detector configured to detect the first DC voltage;

wherein

the wheel side controller generates the first control signal in accordance with a difference between a value detected by the voltage detector and a target value of the first DC voltage.

6. The in-wheel motor system of claim 5, wherein the wheel side controller generates the first control signal in accordance with a number of revolutions and a torque command value of the in-wheel motor.

7. The in-wheel motor system of claim 1, further comprising:

a vehicle body side conversion unit configured to convert a second DC voltage from a battery into a second AC voltage and output the second AC voltage to a vehicle body side coil during powering; and

the battery;

wherein

the power transmitter comprises;

the vehicle body side coil, configured to transmit power wirelessly from the vehicle body during powering; and

a vehicle body side resonance capacitor inserted in series between the vehicle body side conversion unit and the vehicle body side coil.

8. The in-wheel motor system of claim 7, further comprising:

a vehicle body side controller configured to control, with a second control signal, switching of a switch provided in the vehicle body side conversion unit in accordance with a control signal from the communication interface;

wherein

the vehicle body side controller generates the second control signal so as to control the first DC voltage to be constant.

9. The in-wheel motor system of claim 8, wherein the vehicle body side controller generates the second control signal in accordance with a number of revolutions and a torque command value of the in-wheel motor.

10. The in-wheel motor system of claim 8, further comprising:

a vehicle body side current detector configured to detect a current of the vehicle body side conversion unit;

wherein

the vehicle body side controller generates the second control signal in accordance with a difference between a value detected by the vehicle body side current detector and a target current value corresponding to a number of revolutions and a torque command value of the in-wheel motor.

11. The in-wheel motor system of claim 7, wherein during regeneration of the in-wheel motor, the wheel side conversion unit functions as an inverter, and the vehicle body side conversion unit functions as a converter.