Variable three phase induction motor drive scheme with minimal electronic hardware

Induction motors run by inverter drive systems need multiple switching through IGBT transistors with DSP devices and hardware. In this scheme, a method of economically providing a variable drive solution with particular reference to agricultural pump motors is presented. The motor is driven over a variable speed using PWM drive, but using only a single PWM pulse drive instead of three as usual and can work under single phase conditions as well. The use of simpler and low cost microcontroller such as the ATMega 8535 makes it highly cost effective. This has a built in PWM as well as multi channel ADC for feedback speed and D.C. rail voltage sensing. The PWM pulse width is adjusted from time to time for automatic speed control with minimal harmonic torque.