DSK12-C8-000-AA Pacific Scientific AC Servo Drive

The Kollmorgen / Pacific Scientific / Bautz DSK 12 Series AC Servo Drives are meant to control the rotational speed and the torque of AC servo motors, i.e three-phase, synchronous motors excited by permanent magnets. These drives allow acceleration and deceleration in both directions (four-quadrant operation). They are able to commutate the current in the motor phases sinusoidally. For feedback a certain kind of resolver with correct alignment to the rotor is necessary. The current control circuits as well as the speed control circuits of the drive are built in analogous technique. As nominal value for the rotational speed serves a voltage in the range of ±10 V, which normally comes from an external position controller.

For feedback to the external position controller the amplifier in its basic version simulates an encoder with (1024) pulses per revolution. For that reason an external encoder can be dispensed with in most cases. The drive can work directly from the single-phase 230 VAC mains without a transformer, if the motor does not have to deliver a continuous power of more than 1 kW. If the load requires more motor power, use a transformer that generates (3) 230 VAC from a three-phase mains. The drive incorporates a soft-start circuit to limit the starting current. The power rectifier generates a DC voltage of 310 VDC, smoothed by capacitors. These capacitors absorb the back EMF of the motor. If the bus voltage increases, the power dump circuit becomes active and converts the braking power into heat by means of the internal resistors. The internal brake resistors are designed for 50 W continuous duty, but can be overcharged extremely for short periods of time.

The auxiliary voltages for the electronic circuits are internally isolated from the motor supply. To feed them, there is a separate auxiliary supply voltage input for the 230 VAC single phase mains. In case of an "emergency stop" situation, only the motor supply voltages can be switched off, while all outputs including those of the simulated encoder remain active. A brake relay is provided to control the holding brake of a motor by an external auxiliary contactor. All inputs and outputs as well as the supply voltages and the motor connections are placed at the bottom of the DSK unit. All cables connect to plug-in type screw terminals. The simulated encoder output is a Submin-D-Connector.

Analog monitor signals exist on test pins behind the front cover. They deliver a tachometer voltage as motor velocity information and a current monitor signal to be used as torque information, corresponding to the internal current command signal. The pulse width modulation (PWM) of the bus voltage generates the motor currents in the power stage. The power stage is protected against short circuits both phase to phase and phase to ground. All control parameters are adjustable by potentiometers. Additionally, the control parameters can be defined on personality modules to minimize set-up and service time.