SPEED CONTROL DEVICE FOR AC ELECTRIC MOTOR

摘要

A speed control device for an AC electric motor comprising a current controller for dividing the current of an AC electric motor into an exciting current and a torque current or two components on rotating orthogonal two−axis coordinates,to subject the two currents individually to PI−control.The speed control device comprises:a first subtracter(1)for determining a torque voltage saturation amount(ΔVq)from a torque voltage component(Vq')outputted from a torque current controller(47a)and a torque voltage command(Vq*)outputted from a torque voltage limiter(54a);a first integrator(2)for retaining the torque voltage saturation amount(ΔVq);a magnetic flux command corrector(3a)for outputting a magnetic flux command correction amount(Δφ2d)from the retained torque voltage saturation amount(ΔVq')and the rotational angular velocity(ω)of the orthogonal two−axis coordinates;and a second subtracter(4)for subtracting the magnetic flux command correction amount(Δφ2d)from a magnetic flux command(φ2d*),to output a magnetic flux correction command(φ2d*cmd).