Electric drivetrain |
1 | Transmission |
A79/1 | Electric machine 1 |
A79/3 | Power electronics control unit |
S08.10-A024-76
Location
The electric machine 1 (A79/1) is located at the front of the vehicle in the engine compartment and is installed together with the transmission (1) so that transverse to the direction of travel.
Task
During vehicle operation, the electric machine 1 generates mechanical rotational energy from electrical energy to drive the vehicle. During regenerative braking, electrical energy is generated from mechanical energy.
Structure
The electric machine 1 is an asynchronous motor with cage rotor. The rotor is connected to the power output shaft without a mechanical separating point via a fixed-ratio transmission (1). The electrical connection is realized via the power electronics control unit (A79/3).
Function
The electric machine 1 obtains the energy required in motor operation from the high-voltage batteries via the high-voltage on-board electrical system. The power electronics control unit with integrated power inverter converts the direct voltage from the high-voltage batteries into alternating voltage to supply the electric machine 1 with power.
The electric machine 1 can be operated as a motor or an alternator. The power supply and/or recuperation is realized via the integrated power inverter.
The power electronics control unit permanently evaluates the position, number of rotations and temperature of the electric machine via the electric machine left rpm sensor (L6/5), the electric machine right rpm sensor (L6/6) and the electric machine temperature sensor (B94/2).
Electric motor can be operated for forwards travel and reversing in both directions of rotation. Via the transmission, the revolution speed is reduced and half of the torque is directed to the left drive shaft and half to the right drive shaft.
The changeover between the operating modes engine/alternator operation is controlled by the power electronics control unit. For this purpose, the 3-phase currents of electric machine 1 are regulated depending on the operating mode and rotor position. These 3-phase currents generate a magnetic rotating field that generates a mechanical torque together with the rotor field.
In engine mode, this leads to a torque that acts directly on the drive and thus powers the vehicle. In generator mode, the electric machine 1 generates a braking torque.