3-Phase Sinusoidal Motor Controller

A4923

8

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

The internal sine modulation signal is converted to a PWM signal

to drive the motor terminals. A 20 kHz carrier is modulated with

the current sine profile value and used to generate the gate drive

signals. Thus, the motor terminal voltage is a 20 kHz PWM sig-

nal with a duty cycle dependent upon the sine modulation signal.

The high- and low-side gate drivers on a given motor terminal are

enabled inverted of the other, with a dead-time added to ensure

both drivers will never be enabled at the same time. For increased

efficiency, torque ripple, and audible noise, the sine profile is

advanced 7.5º of one electrical revolution, relative to the hall

transitions.

64 Steps

64 Steps

64 Steps

6 Bits of

Resolution

One Electrical Revolution

Sx + VCP

Sx

VREG7.2

0

VBB

0

Sine Drive Modulation Signal

High-side Gate Drive

Low-side Gate Drive

Motor Terminal Voltage

Figure 2: Sine Modulation Signal