| 摘要 |
PROBLEM TO BE SOLVED: To realize a circuit for easily controlling the torque of a three-phase motor. SOLUTION: Current sensors 7a, 7b are provided respectively in two phases of the output of a power device driving circuit 2 for causing currents to flow into a three-phase motor M, and individual detected current waveforms are inputted to a phase current compounding circuit 8. In the phase-W calculating part 8c of the phase current compounding circuit 8, the current waveforms of the remaining phases are found, and individual current waveforms flowing in the three phases are half-wave rectified by first, second, and third ideal half-wave rectifying units 8a, 8b, 8d, and are added and compounded in a three- phase adder circuit 80. The half-wave compounded current waveform is caused to pass a low-pass filter 9 and is inputted to a torque control circuit for performing the torque control of the motor as a feedback current value. Consequently, it is enabled to find a feedback current value by providing current sensors in two phases only and to simplify the circuit for controlling the torque and reduce its cost. |
