Patent ID: 8664898

Claim:
A device for stopping an induction motor, the device comprising: a frequency commanding unit for generating an operating frequency corresponding to a rotational speed command of the induction motor; a q-axis and d-axis Voltage/Frequency (V/F) converter for outputting a first q-axis voltage (Vq 1 ) proportional to the generated operating frequency and a first d-axis voltage (Vd 1 ) proportional to a 0 frequency; a q-axis Proportional-Integral (PI) current controller for outputting a second q-axis voltage (Vq 2 ) for stopping the induction motor when the operating frequency reaches a stopping frequency; a d-axis PI current controller for outputting a second d-axis voltage (Vd 2 ) for stopping the induction motor when the operating frequency reaches the stopping frequency; a selection unit for selecting and outputting the first q-axis and d-axis voltages (Vq 1 and Vd 1 ) or the second q-axis and d-axis voltages (Vq 2 and Vd 2 ) according to the operating frequency generated by the frequency commanding unit; a q-axis integral initial value setting unit for setting an integral initial value of the q-axis PI current controller by using the first q-axis voltage (Vq 1 ) occurring at the timing when the operating frequency reaches the stopping frequency; a d-axis integral initial value setting unit for setting an integral initial value of the d-axis PI current controller by using the first d-axis voltage (Vd 1 ) occurring at the timing when the operating frequency reaches the stopping frequency; and a stopping amount commanding unit for generating a final current target value (IRef) according to a DC stopping amount when the operating frequency reaches the stopping frequency, wherein the selection unit selects the first q-axis and d-axis voltages (Vq 1 and Vd 1 ) if the operating frequency corresponds to the driving frequency, and selects the second q-axis and d-axis voltages (Vq 2 and Vd 2 ) when the operating frequency reaches the stopping frequency.