1993 Volume 113 Issue 3 Pages 333-340
For a variable speed induction motor drive, the control system without a speed sensor and a PWM current source inverter have been proposed. For this system, a voltage sensor and a current sensor are required instead of the speed sensor. The motor speed can be estimated by the measured instantaneous values of the voltage and the current. Since the PWM current source inverter is clearly superior to the PWM voltage source inverter in terms of voltage and current waveforms, i.e., sinusoidal waveforms, a more accurate estimation of the speed can be achieved.
In this paper, the PWM current source inverter-induction motor drive without a speed sensor is presented, The used inverter can regulate the output current by PWM control under a fixed input dc current. The quick regulation of the ac current is achieved in this system because of the no influence of the dc link parameters. The effect of the filter capacitor in the inverter circuit on the current regulation is discussed. To eliminate the ac current sensors of the motor, the relationship between the inverter currents and the motor currents is made clear. The experiments show that the system without the ac current sensors has the same steady-state and transient characteristics as that of the system with the voltage and the current sensors.