User Manual

System Specification

3-Phase BLDC Motor Control with Sensorless Back-EMF, ADC, Zero Crossing, Rev. 3

Freescale Semiconductor 11

Preliminary

Figure 3-6 shows branch and motor phase winding voltages during a 0-360°electrical interval. Shaded

rectangles designate the validity of the equation (EQ 3-6.). In other words, the Back-EMF voltage can be

sensed during designated intervals.

0 30 60 90 120 150 180 210 240 270 300 330 360 39

uVA

Figure 3-6. Phase Voltage Waveforms

4. System Design Concept

4.1 System Specification

• Control technique incorporates

— using AD converter for sensorless Back-EMF Zero Crossing commutation control

— motoring mode

— single speed feedback loop

— both direction of the rotation

• Targeted for 56F80xEVM platforms

• Running on one of three optional board and motor hardware sets

— Low Voltage Evaluation Motor hardware set

— Low Voltage hardware set

— High Voltage hardware set at variable line voltage 115 - 230V AC

• Overvoltage, Undervoltage, Overcurrent, and Temperature Fault protection

• Manual Interface (Start/Stop switch, Up/Down push button control, LED indication)

• PCMaster Interface

• Power Stage Identification with control parameters set according to used hardware set