Integra CROMA24 service manual Servo Motor Controller

Croma24 Service Manual

2.Motor current sense

The voltage across a series current sense resistor is measured and level shifted so that it is centered around 5 V.

3.Comparator

This portion divides the output of the reference waveform gen- erator by two and compares it to the output of the motor current sensor. Logic inside the gate array generates the control signals for the power driver that applies voltage across the motor wind- ing in order to make the actual current match the reference waveform.

4.Power driver

An H-bridge allows the supply voltage to be applied across the winding in either polarity to drive the current to the desired value.

Servo Motor Controller

Figure 2-7. Servo Motor Controller.

The Carrier Assembly is driven by the Servo Motor. The speed of the Carrier Assembly is controlled by varying the duty cycle of the power applied to the controller. The microprocessor checks the position of the Carrier Assembly approximately 1,000 times per second (during the servo interrupt). It then updates the PWM (pulse width modula-

34 Theory of Operation