AN1914 Freescale Semiconductor / Motorola, AN1914 Datasheet - Page 8

• Manufacturer Part Number: AN1914
• Description: 3-Phase BLDC Motor Control with Sensorless Back EMF Zero Crossing Detection Using DSP56F80x
• Manufacturer: Freescale Semiconductor / Motorola

Target Motor Theory
8
The second goal of the model is to find how the motor characteristics depend on the switching angle.
The switching angle is the angular difference between a real switching event and an ideal one (at the
point where the phase to phase Back-EMF crosses zero).
The motor-drive model consists of a normal three phase power stage plus a Brushless DC motor. The
power for the system is provided by a voltage source (U
controlled elsewhere, allow the rectangular voltage waveforms (see
semiconductor switches and diodes are simulated as ideal devices. The natural voltage level of the
whole model is put at one half of the DC bus voltage. This simplifies the mathematical expressions.
DSP56F80x MC PWM Module in Motor Control Applications
Figure 3-5. Power Stage - Motor Topology
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d
). Six semiconductor switches (S
Figure
3-2) to be applied. The
A/B/C t/b
),