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Power pack proportional DC motor control

Compact gensets and industrial gensets are often operated in S/W mode only. For certain tasks, however, the power packs can also be implemented with variable speed. An example of a hydraulic power pack with proportional control of a DC motor is shown below.

Example of variable speed drive


Various DC motors are possible in principle. Shunt or series motors as well as permanent magnet DC motors (PMDC motors). In this example, a PMDC motor is used. This is characterized by the fact that the field is generated by a permanent magnet. The commutation of this motor is implemented with the help of carbon brushes.

An 800 Watt motor is used.

Motor control

The motor control for the aggregate is realized in this case by a half bridge. A reversal of the direction of rotation is not possible with this. This function is generated hydraulically via a 4/3-way valve. T1 PWM is controlled for proportional control.

The entire motion sequence as a step chain and the monitoring are integrated in the electronic control. The current and the motor speed are monitored. Optionally, the pressure can also be recorded.

Hydraulic circuit

The hydraulic circuit consists of a gear pump, a pressure relief valve which protects the system against overload, a 4/3-way control valve and a shut-off seat valve.