3-Phase BLDC Motor Sensorless Control Using MC56F8013

Introduction• Ability to sequentially scan and store up to eight measurements• Ability to scan and store up to four measurements each on two ADCs operating simultaneously andin parallel• Ability to scan and store up to four measurements each on two ADCs operating asynchronously toeach other in parallel• Interrupt generating capabilities at end of scan, when out-of-range limit is exceeded, and on zerocrossing• Optional sample correction by subtracting a pre-programmed offset value• Signed or unsigned result• Single ended or differential inputs• PWM outputs with hysteresis for three of the analog inputsThe ADC is used to measure DC-bus voltage, DC-bus current, and back-EMF phase voltages. The ADC’shigh/low level detection capability provides automatic detection of the DC over-voltage and DCunder-voltage, serviced in the associated interrupt service routine (ISR).The application uses the ADC block in simultaneous mode and sequential scan. It is synchronized withPWM pulses. This configuration allows the simultaneous conversion, within the required time, of requiredanalog values of all phase currents, voltage and temperature.The quadrature timer is an extremely flexible module, providing all required services relating to timeevents. It has the following features:• Four 16-bit counters/timers• Count up/down• Counters are cascadable• Programmable count modulo• Maximum count rate equal to the peripheral clock/2, when counting external events• Maximum count rate equal to the peripheral clock/1, when using internal clocks• Count once or repeatedly• Counters are preloadable• Counters can share available input pins• Each counter has a separate prescaler• Each counter has capture and compare capabilityThe application uses four channels of the quadrature timer for PWM to ADC synchronization andcommutation timing. Another channel of the quadrature timer module is set to generate a timebase for aspeed and alignment controller.3-Phase BLDC Motor Sensorless Control using MC56F8013, Rev. 012 Freescale Semiconductor