AN2009 datasheet(32/39 Pages) STMICROELECTRONICS

No. de pieza	AN2009

Descripción Electrónicos	PWM MANAGEMENT FOR 3-PHASE BLDC MOTOR DRIVES USING THE ST7MC

PDF	39 Pages

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Fabricante Electrónico	STMICROELECTRONICS [STMicroelectronics]

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PWM MANAGEMENT FOR 3-PHASE BLDC MOTOR DRIVES USING THE ST7MC

Figure 21. Step

Σ3 (switches T2-T1 are ON)

When switching from step

Σ3 (switches T2-T1 are ON) to step Σ4 (switches T2-T3 are ON), a

free-wheeling, decreasing demagnetization current is still present through the C terminal

(dashed line in Figure 22) and an increasing magnetization current appears through the B ter-

minal (dotted line). Figure 22 shows these two currents during the PWM ON time.

Figure 22. Step

Σ4 (switches T2-T3 are ON) during the demagnetization PWM ON time

This means, during the PWM ON time:

– The potential of B is HV

Normal

current

free-wheeling current

for BEMF reading (ST method)

PWM on T2

free wheeling

demagnetization

current

Normal mode

magnetization

current

AN2009 Datasheet(PDF) 32 Page - STMicroelectronics