TAP-TAPER 4C5000 - Caterpillar

Switched Reluctance (SR) Electric Drive Motor
Illustration 10 g06179169
Electric Drive Motor
(3) Electric Drive MotorThe electric drive motor (3) is mounted to the rear of the drop gearbox and is used to drive the drop box gear set.The electric drive motor is a three-phase switched reluctance motor. The electric drive motor receives three-phase voltage from the power inverter. The speed and the direction of the electric drive motor will determine the speed and direction of travel of the machine.The power train ECM will exercise travel speed control over the system. The power train ECM will continuously monitor the input signals from the operator controls and the actual drive motor speed. The ECM will adjust the travel command to the electric motor ECM, according to the input signals.Under some machine conditions, the electric drive motor is used for dynamic braking of the machine. When the travel speed of the machine exceeds the commanded travel speed, power to the drive motor will decrease. The motor will begin to act as a generator and produce electrical current. The power inverter control ECM will exercise control over the power transistors that will direct this current back through the power inverter to the generator. The generator will act against the engine and the speed of the engine will increase. The result will be a dynamic braking action that will slow the machine travel.As the speed of the engine approaches 2000 RPM during dynamic braking, the power train ECM will command subsystem components such as demand fan and implement pump to turn ON for additional energy dissipation capability. When all available braking capability is reached, the power train ECM will reduce the dynamic braking of the motor. The ECM will maintain machine dynamic braking and keep the engine speed just below 2050 RPM.If operating on a grade, and the current machine speed exceeds the allowed or selected travel speed on that grade, the power train ECM will command service brakes to come on. The combination of dynamic braking and machine braking will provide the force that is required to slow the machine to maintain the selected speed.When the FNR switch is in the NEUTRAL position, and the machine is not moving, the power train ECM will send the electric drive motor a "zero" torque command. When the FNR switch is in the NEUTRAL position and the parking brake is in the OFF position, the machine will be allowed to roll. In this condition, if the machine speed reaches approximately 12 km/h (7.5 mph) the machine will automatically select the Forward or Reverse position to control the machine speed by modulating the electric motor torque command.The electric drive motor is cooled by two separate systems. When the engine is running, power train oil is circulated through the electric drive motor, and sprayed inside the case. The oil is sprayed on the ends of the motor windings. Power train oil is also used to lubricate the rotor bearings in the drive motor. When the engine is running, separate circuit