Patent ID: 7170245

Claim:
A motor power supply control apparatus including a DC power supply part having a pair of power supply terminals, and an inverter having a pair of connection terminals connected to each other by an additional line, respectively, connected to the pair of power supply terminals of the DC power supply part to receive DC power from the DC power supply part and to supply AC power to a motor, the motor power supply control apparatus comprising: a power supply line connecting the pair of connection terminals to each other; a braking resistor disposed in the power supply line connecting the pair of connection terminals to each other; a control switching element disposed in series with the braking resistor in the additional line; a braking switch disposed to one of the connection terminals and switching to either a normal position connecting the one of the connection terminals to a corresponding power supply terminal, or a braking position connecting the one of the connection terminals to the additional line; a motor speed detector detecting a speed of the motor; a control part controlling the braking switch to switch to the braking position and controlling the control switching element so that an on-off interval of the control switching element is controllable depending on the speed detected by the motor speed detector, when the AC motor is in a dynamic braking mode; and an over voltage protection resistor having a side connected between the braking resistor and the control switching element, and a remaining side connected to the one connection terminal to be placed in series with the control switching element.