Patent ID: 7531974
Filing Date: 2009-05-12
Classification: B60L,F02D,H02P,Y02T

Abstract:
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.