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EPS Control Unit

As well as the control circuitry, the EPS control unit also contains the power electronics for operating the electric motor.

The power electronics includes a multiple output relay that turns off the power supply to the motor windings in the event of a fault. Breaking the circuit allows the motor shaft to rotate freely. Fault conditions in which the motor would electrically lock up are avoided.

There is a temperature sensor integrated in the control unit that is required for detecting overload situations.

Fig 1: Identifying EPS Control Unit And Electric Motor Housing Components
G06896610Courtesy of BMW OF NORTH AMERICA, INC.
INDEX EXPLANATION REFERENCE CHART

Index Explanation
1 Electric motor housing
2 Steering torque sensor lead connection
3 Bus connection
4 Cable to steering torque sensor
5 Power supply connection
6 Diaphragm made of Goretex
7 EPS control unit housing

The housing of the EPS control unit (and the electric motor) is located in a position exposed to large temperature fluctuations and high external moisture levels. Therefore, there is a diaphragm made of Goretex on the housing that equalizes the pressure difference between the inside and outside of the housing but still prevents moisture intrusion at that point.

On the EPS control unit and electric motor housing there are also the following EPS electrical connections: