ML4423

July 2000 ML4423* 1, 2, or 3-Phase Variable Speed AC Motor Controller GENERAL DESCRIPTION The ML4423 provides the PWM sinewave drive signals necessary for controlling three phase AC induction motors as well as single and two phase split capacitor AC induction motors. A constant voltage/frequency ratio can be maintained over a frequency range of greater than 10:1, providing 15Hz to 150Hz control. The output variable frequency AC voltages are sensed and fed back to the controller to track the sinewave frequency and amplitude set at the speed control input. Direction, on two and three phase motors, is controlled by changing the relative phase difference between the motor windings: 90× for two phase motors and 120× and 240× for three phase motors. To protect the motor, power devices, high voltage drivers and control circuitry, the ML4423 includes fixed period, pulse by pulse variable duty cycle current limit, deadtime circuitry, and undervoltage lockout. The ML4423 has selectable output voltage swing of 5V or 12V for interfacing to different high side drivers and power devices. FEATURES s s s s s s s s s Drives single, two, and three phase AC motors Greater than 10:1 variable speed control range Constant V/F ratio with programmable end points Reverse capability for two and three phase motors Low distortion PWM sinewave drive Eliminates run capacitors in PSC motors Coast function for quick power disable Low cost interface for various gate drivers PWM current limit, undervoltage...