THESE ARE NEW ICS FROM THE MANUFACTURE. ML4421CP MOTOR CONTROLLER IN A DIP PACKAGE
The ML4421 ac induction motor controller provides the PWM sin 0 degrees and sin
90 degrees waveforms necessary for controlling single- and two-phase ac
induction motors. The device offers a constant voltage/frequency ratio over a
10:1-rpm range, and maintains a selected speed within 5%.
continuously monitors the motor's speed and adjusts the drive waveform in both
frequency and amplitude. The speed is determined from the phase difference
between the voltage and current driving the motor. The ML4421 comes in 28-pin
A circuit for powering a two-phase AC induction motor. The circuit generates a first signal of the form Vdc+A sin(2.pi.ft-0.degree.) and a second signal of the form Vdc+A sin(2.pi.ft-90.degree.). The first signal is input to a first error amplifier along with a first sampled difference signal from the motor. The second signal is input to a second error amplifier along with a second sampled difference signal from the motor. The outputs from each of the first and second amplifiers is input into a first comparator and a second comparator along with a sawtooth waveform to create a first sinusoidally modulated square wave signal and a second sinusoidally modulated square wave signal. The first and second sinusoidally modulated square wave signals are fed to driver circuits which in turn control an H-bridge circuit for powering the motor from a DC bus.