AN1913 Motorola / Freescale Semiconductor, AN1913 Datasheet - Page 10

• Manufacturer Part Number: AN1913
• Description: AN1913 3-phase BLDC Motor Control with Sensorless Back-EMF ADC Zero Crossing Detection using DSP 56F80x
• Manufacturer: Motorola / Freescale Semiconductor

System Design Concept
4.
4.1 System Specification
10
There are two necessary conditions which must be met:
The
Shaded rectangles designate the validity of the equation (EQ 3-6.). In other words, the Back-EMF
voltage can be sensed during designated intervals.
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System Design Concept
Figure 3-6
Top and bottom switch (in diagonal) have to be driven with the same PWM signal
No current is going through the non-fed phase used to sense the Back-EMF
Control technique incorporates
— using AD convertor for sensorless Back-EMF Zero Crossing commutation control
— motoring mode
— single speed feedback loop
— both direction of the rotation
Targeted for DSP56F80xEVM 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
shows branch and motor phase winding voltages during a 0-360°electrical interval.
0
BLDC control with BEMF Zero Crossing using ADC
30
Figure 3-6. Phase Voltage Waveforms
60
90
120
150
x
=
180
A B C
210
240
270
300
330
360
uVA
uA
390