US 7,531,974 B2
Apparatus and method for controlling a motor
Hideaki Ohtsuka, Yokohama (Japan); and Hidehiko Sugita, Zama (Japan)
Assigned to Nissan Motor Co., Ltd., Yokohama-shi, Kanagawa (Japan)
Appl. No. 10/575,203
PCT Filed Dec. 14, 2005, PCT No. PCT/IB2005/003774
§ 371(c)(1), (2), (4) Date Apr. 10, 2006,
PCT Pub. No. WO2006/097789, PCT Pub. Date Sep. 21, 2006.
Claims priority of application No. 2004-362451 (JP), filed on Dec. 15, 2004; and application No. 2005-327148 (JP), filed on Nov. 11, 2005.
Prior Publication US 2008/0297087 A1, Dec. 04, 2008
Int. Cl. H02P 27/08 (2006.01); H02P 6/06 (2006.01)
U.S. Cl. 318—146  [318/151; 318/158; 318/453; 318/465; 318/504] 27 Claims
OG exemplary drawing
 
1. A motor control device for use in controlling an electric motor driven by a power generator that is adapted to output a square-wave voltage and a PWM-wave voltage in response to a switching control signal, comprising:
(a) a first input adapted to receive a signal indicative of a torque instruction value;
(b) a second input adapted to receive a signal indicative of the rotational speed of the electric motor; and
(c) a controller responsive to the first and second inputs and adapted to: determine the existence of a switching condition based on the first and second inputs; if a switching condition exists, generate a voltage control signal to lower the output voltage of the power generator; when the output voltage of the power generator is below a specified voltage level, generate the switching control signal to cause the power generator output to switch from the PWM-wave voltage output to the square-wave voltage output.