TB6548F/FG

2006-03-02

7

6.

Lead Angle Control

The lead angle is 0 degrees during the starting forcible commutation and, when normal commutation is

started, automatically changes to the lead angle that has been set using LA0 and LA1. However, if both

LA0 and LA1 are set for High, the lead angle is 30 degrees in the starting forcible commutation as well as

in normal commutation.

7.

Lap Turn-on Control

When SEL_LAP

= High, the turn-on electrical angle is 120 degrees. When SEL_LAP = Low, Lap Turn-on

Mode starts.

In Lap Turn-on Mode, the time between zero-cross point and the 120-degree turn-on timing becomes

longer (shaded area in the below chart) so as to create some overlap when switching turn-on signals. The

lap time varies depending on the lead angle setting.

(3) Lead angle: 15 degrees

OUT_WN

OUT_VN

OUT_WP

Induced voltage

Turn-on signal

(1) Lead angle: 0 degrees

OUT_UP

OUT_UN

OUT_VP

OUT_VN

OUT_WP

OUT_WN

(2) Lead angle: 7.5 degrees

OUT_UP

OUT_UN

OUT_VP

OUT_UP

OUT_UN

OUT_VP

OUT_VN

OUT_WP

OUT_WN

(4) Lead angle: 30 degrees

OUT_UP

OUT_UN

OUT_VP

OUT_VN

OUT_WP

OUT_WN

UV

W

30 degrees

22.5 degrees

15 degrees

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

(3) Lead angle: 15 degrees

OUT_WN

OUT_VN

OUT_WP

Induced voltage

Turn-on signal

(1) Lead angle: 0 degrees

OUT_UP

OUT_UN

OUT_VP

OUT_VN

OUT_WP

OUT_WN

(2) Lead angle: 7.5 degrees

OUT_UP

OUT_UN

OUT_VP

OUT_UP

OUT_UN

OUT_VP

OUT_VN

OUT_WP

OUT_WN

(4) Lead angle: 30 degrees

OUT_UP

OUT_UN

OUT_VP

OUT_VN

OUT_WP

OUT_WN

UV

W

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control

PWM control