The Heitz System 4 Servo Amplifier is designed to drive brush-type DC motors at up to 60 volts and a short peak of 100 amps. It consists of two boards: a full-bridge FET driver and a power-FET bridge. The FET bridge has a parallel set of 200 amp power FETS. The Driver board plugs in to the upper side of the Motherboard, and the Power Board plugs into the lower side, where it also attaches to a heat sink.
The Servo Amplifier takes a PWM signal from the microcontroller and drives the power bridge, with analog current feedback to the microcontroller.
Current Limiting The FET Power Board can produce over 150 amps. The peak motor current is limited on a cycle-by-cycle basis as set by a potentiometer on the Driver board.
Current Feedback Circuit The current feedback circuit supplies RMS current to a "foldback" inner loop. The RMS output represents motor heating in both oscillating and unidirectional operation. The foldback circuit allows short-term high current output, but keeps the long-term average to the motor's continuous rating.