Abstract: In a slip frequency control system hitherto widely employed as a control system for an induction motor type electric rolling stock (in which a slip frequency is determined from a current deviation, an inverter frequency is calculated from the slip frequency and a motor rotation frequency, and the inverter frequency is multiplied by a predetermined correction factor to determine a modulation rate, thereby operating an inverter), a motor output torque decreases in a low speed region. It is difficult to make the correction for this decrease of torque by detecting the torque. In the present invention made considering that a torque curve and sin .phi. (.phi.: the internal impedance angle of a motor) obtained from the result of simulation resemble each other, the decrease of sin .phi. is regarded as being the decrease of torque and a voltage to frequency ratio is corrected so as to compensate for the decrease of sin .phi..

Abstract: A control for an inverter-driven switched reluctance generator includes an angle control for generating a turn-on angle signal and a pulse width angle signal for switching respective inverter switches according to a function F(.theta..sub.on, .theta..sub.off) which depends on the machine geometry and speed of operation. A linearizer is provided for adjusting the turn-on angle signal and the pulse width angle signal by varying the value of the function F(.theta..sub.on, .theta..sub.off) inversely with the dc bus voltage so as to maintain a substantially constant average generator current. In this way, open loop operation of the switched reluctance generator drive is stabilized, and closed loop operation is improved, i.e., by making the system response to step load and commanded voltage changes independent of the dc bus voltage.