Independent Switching Of Power Transistors - Motorola M68HC08 Manual

3.2 Independent Switching of Power Transistors

DRM046 — Rev 0
MOTOROLA
Freescale Semiconductor, Inc.
U
DCB
PWM_Q1
C1
PWM_Q2
GND
Figure 3-3. 3-phase BLDC Power Stage
In both modes the 3-phase power stage energizes two motor phases
concurrently. The third phase is unpowered (see Figure 3-2. Voltage
Strokes Applied to the 3-ph BLDC Motor). Thus, we get six possible
voltage vectors that are applied to the BLDC motor using a PWM
technique. There are two basic types of power transistor switching:
independent switching, and complementary switching.
With independent switching, only two transistors are switched on when
current is conducted from the power supply to the phase of the BLDC
motor. In one phase, the top transistor is switched on; in the second
phase, the bottom transistor is switched on and the third phase is not
powered. During freewheeling all transistors are switched off (see
Figure 3-4. Independent Switching of Power
BLDC Motor Theory
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Independent Switching of Power Transistors
Q1 Q3
PWM_Q3
Q2 Q4
PWM_Q4
Phase_A Phase_B
BLDC Motor Theory
Q5
PWM_Q5
Q6
PWM_Q6
Phase_C
Transistors).
Designer Reference Manual
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