STK6103

No. 4290- 4/11

Sample Application Circuit

Description of Operation

The DC 3-phase brushless motor generally uses a permanent magnet for the rotor and places the stator coil around it.

When the rotor and stator coil are excited, magnetic force is generated between the poles, which is used for revolution

torque. For efficient revolution it is necessary to know precisely where the rotor pole is in relation to the stator pole. In

the brushless motor Hall devices and Hall ICs are widely used for this purpose, by detecting the electric power generated

along the lines of magnetic force.

(1)

Motor rotating force

The block diagram for this HIC is given in Fig. 2.

The conditions before input of V

pin H level and Vref

The position detect signal at this time, due to the effect of

the rotor magnetic field, will be output signals from 1 or 2 devices (of the 3) so that H

to 12. The signals input to pins 7 to 12 are input to the motor controller and converted into signals compatible with

3-phase brushless motor revolution. When V

MOSFET gate voltage V

This outputs excitation current to the motor phase windings as indicated in the timing

chart (Fig. 3), and rotating the motor.

For revolution speed control, the Vref

efficiency, controlling the conduction of motor current Io (Fig. 1). Control of Io means control of power supplied

to the motor, which controls motor rpm. In general motor rpm N is proportional to the PWM on duty (when motor

load is constant). The PWM on duty is proportional to the size of Vref

outlined below.

Ν ∝ PWM ON Duty ∝ Vref

1

Fig.1 PWM Drive Principle