Patent ID: 6850031

Claim:
An electric motor controller comprising: an inverter circuit having switching devices and diodes for converting a direct current into an alternating current (AC) and supplying an AC power to a motor, a motor current detection section for detecting a current flowing through said motor and outputting a detected signal, and an inverter control section for controlling said inverter circuit on the basis of the output of said motor current detection section, wherein said inverter control section comprises: a frequency setting section for outputting the command signal of the rotation frequency of said motor, a wave generation section for generating a rotation phase signal from the command signal of said frequency setting section, a reactive current computing section for computing a reactive current from the rotation phase signal of said wave generation section and the detected signal of said motor current detection section, a reactive current command section for outputting the command value of the reactive current, an error voltage computing section for computing an error voltage from the difference between the output of said reactive current computing section and the output of said reactive current command section, a V/f conversion section for obtaining a reference voltage from the command signal of said frequency setting section, an adder for computing a command value of voltage applied to the motor from the outputs of said error voltage computing section and said V/f conversion section, and an output command computing section for generating a control signal from the outputs of said wave generation section and said adder and supplying the control signal to said inverter circuit.