System Outline

This system controls the following systems in order to achieve the most efficient operations for the current the driving conditions.

1. Motor Generator 
   1. Supplies electrical power from the HV battery to motor generator no. 2 (Front) in order to provide the motive force to drive the wheels.
   2. Whenever the wheels are being driven by the engine via the planetary gears, motor generator no. 1 (Front) activates to generate and supply electricity to motor generator no. 2 (Front) in order to allow it to drive the wheels.
   3. When the vehicle is decelerating, kinetic energy from the wheels is converted into electrical energy by motor generator no. 2 (Front) and used to recharge the HV battery.

   The hybrid vehicle control ECU switches between these modes (1, 2, 1+2, or 3) according to the driving conditions. However, when the HV battery charge is low, the HV battery will be charged by the engine turning motor generator no. 1 (Front).

2. Inverter 

   * The inverter converts high-voltage direct current from the HV battery into three-phase alternating current for driving motor generator no. 1 (Front) and motor generator no. 2 (Front).

   * The activation of the power transistors is controlled by the motor generator control computer. In addition, the inverter transmits necessary information for current control, such as the output amperage or voltage, to the motor generator control computer.

   * Along with motor generator no. 1 (Front) and motor generator no. 2 (Front), the inverter is cooled by an exclusive radiator in the coolant system that is separate from the engine radiator.

   * In the event of a vehicle collision, a circuit breaker sensor installed in the inverter outputs a collision signal to stop the system.

   * A boost converter has been adopted in the inverter, which increases the rated voltage output from the HV battery from DC 288V, to DC 650V. After increasing the voltage, the inverter converts the direct current to alternating current.

3. Converter 

   The power source for auxiliary equipment in the vehicle, such as the lights, audio system, and the air conditioning system, as well as the ECUs, is based on a system with a rated voltage of DC 12V. Because the HV battery outputs at DC 288V, the converter is used to transform the voltage from DC 288V to DC 12V when needed in order to recharge the auxiliary battery. The converter is installed on the underside of the inverter.

4. HV Battery 

   * In the RX 400h, a sealed nickel hydride (Ni-MH) battery has been adopted. This HV battery has a high power density, is lightweight and has a long lifespan to match the characteristics of the hybrid system. Because the hybrid system controls the charge/discharge to maintain the SOC (State of charge) at a constant level while the vehicle is driving, it does not have to rely on the use of external recharging.

   * The HV battery, battery voltage sensor, system main relay and the cooling fan are put in a signal case which is placed in the rear seat to make more effective use of vehicle space.

   * A service plug that shuts off the circuit is provided in the middle of the 30 modules (Rated battery capacity = 288V). Before servicing any portion of the high-voltage circuits, make sure to remove the service plug.

   Please do not have the car in READY ON when you are removing the service plug. There is a possibility that battery voltage sensor will be damaged.

   * To ensure the HV battery performance, the battery voltage sensor controls the operation of the cooling fan to avoid build up of any heat that is generated in the HV battery during charging and discharging.

5. Regenerative System Operation 

   This system operates the motor as a generator to change the kinetic energy of the vehicle into electricity when the accelerator pedal is released or when the vehicle is decelerated via the brake pedal, and stores the generated electricity in the battery.

6. E-Four System 

   The E-Four system optimizes the motive force distribution under various driving conditions by changing from front-wheel drive mode, which focuses on fuel consumption, to four-wheel drive mode, which focuses on traction performance. The change is brought about by driving the front wheels with the motor generator no. 2 (Front) and the rear wheels with the motor generator (Rear).