Pwm control pic

AN900
Controlling 3-Phase AC Induction Motors Using the PIC18F4431
Author: Jon Burroughs Microchip Technology Inc. The three peripherals and their features are: 1. Power Control PWM (PCPWM) module: • Up to 8 output channels • Complimentary PWM outputs • Two hardware Fault protection inputs • PWM resolution up to 14 bits • Edge-aligned or center-aligned operation • Flexible dead time • Simultaneous update of duty cycle and period Motion Feedback Module (MFM), comprised of a Quadrature Encoder Interface (QEI) and an Input Capture module (IC): • Standard quadrature encoder inputs (QEA, QEB and Index) (QEI) • High and Low Resolution Position Measurement modes (QEI) • Velocity Measurement mode using Timer5 (QEI) • Interrupt with configurable priority on event detection (QEI) • Pulse Width Measurement and Period Measurement modes (IC) • Edge and state change capture (IC) High-Speed Analog-to-Digital Converter (HSADC): • Two independent sample-and-hold circuits • Single or multi-channel selection • Sequential or Simultaneous Conversion modes • Four-word FIFO result buffer with flexible interrupts

INTRODUCTION
Previous Microchip authors (Parekh and Yedamale) have described the implementation of a 3-phase AC induction motor (ACIM) control with PICmicro® devices. The first application note (AN843) detailed ACIM control with the PIC18F452. More recently, ACIM control has been implemented with the PIC16F7X7 family of devices (AN889). This application note describes how the PIC18F4431 may be used to control an ACIM using open and closed-loop V/f control strategies. The application code is built incrementally and demonstrates the following control methods: 1. 2. 3. Voltage-frequency (V/f) control Voltage-frequency control with current feedback Voltage-frequency control with velocity feedback and PID control

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The PIC18F4431 incorporates a set of innovative peripherals, designed especially for motor control applications. The utility of these peripherals is