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System Description

  1. BASIC OPERATION 
    1. This system generates a motive force by combining the engine, MG1, and MG2 in accordance with the driving conditions. Representative examples of the various combinations are described below.
    2. Supply of electrical power from the HV battery to MG2 provides force to drive the rear wheels.
      Fig 1: Electrical Power Supply Diagram
      G05303684Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. While the rear wheels are being driven by the engine via the planetary gears, MG1 is also being driven by the engine via the power split planetary gear unit, in order to supply the electricity that MG1 generates to MG2.
      Fig 2: Electrical Power Supply Diagram
      G05303685Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. MG1 is also driven by the engine via the planetary gears, in order to charge the HV battery.
      Fig 3: Electrical Power Supply Diagram
      G05303686Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    5. When the vehicle is decelerating, kinetic energy from the rear wheels is recovered and converted into electrical energy by means of MG2, and used to recharge the HV battery.
      Fig 4: Electrical Power Supply Diagram
      G05303687Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. SYSTEM DIAGRAM 
    Fig 5: Hybrid Control System - System Diagram
    G05303688Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. FUNCTION OF MAIN COMPONENTS 
    FUNCTION OF MAIN COMPONENTS

    Component Function
    Hybrid Transmission MG1 MG1, which is driven by the engine, generates high-voltage electricity in order to operate MG2 or charge the HV battery. Also, it functions as a starter to start the engine.
    MG2
    • Driven by electrical power from MG1 or the HV battery, and generates motive force for the rear wheels.
    • During braking, or when the accelerator pedal is not depressed, it generates electricity to recharge the HV battery (Regenerative brake control).
    Power Split Planetary Gear Unit Distributes the engine's drive force as appropriate to directly drive the vehicle as well as drive MG1.
    2-stage Motor Speed Reduction Planetary Gear Unit Reduces the rotational speed of MG2 in accordance with the characteristics of the planetary gear set, in order to increase torque. Furthermore, it shifts the transmission in two stages in accordance with the conditions of the vehicle.
    HV Battery
    • Supplies electrical power to MG1 and MG2 in accordance with the driving conditions of the vehicle.
    • Recharged by MG1 and MG2 in accordance with the SOC (state of charge) and the driving conditions of the vehicle.
    Inverter with Converter Assembly Inverter Assembly A device that converts the high-voltage DC (HV battery) into AC (MG1 and MG2) and vice versa (converts AC into DC).
    Boost Converter Boosts the maximum voltage of the HV battery from DC 288 V to DC 650 V and vice versa (drops DC 650 V to DC 288 V).
    MG ECU Controls the inverter and boost converter in accordance with the signals received from the HV control ECU, thus driving MG1 and MG2 causing them to generate electricity.
    Hybrid Vehicle Converter (DC/DC Converter) Converts a voltage of DC 288 V into a DC voltage between 12 V and 14 V in order to supply electricity to body electrical components, as well as to recharge the auxiliary battery (DC 12 V). Contains the SMRP.
    SMRP Completes the initial connection of the high-voltage circuit through a resistor to allow a controlled precharge of the high-voltage system. SMRP is a semiconductor relay that is located in the hybrid vehicle converter (DC/DC converter).
    HV Control ECU Effects comprehensive control of the THS-II system.
    • Information from each sensor as well as from the ECU (ECM, battery smart unit, skid control ECU, and EPS ECU) is received, and based on this information, the required torque and output power is calculated. The HV control ECU sends the calculated result to the ECM, inverter with converter assembly, and skid control ECU.
    • Monitors the charging condition of the HV battery.
    • Controls the HV battery cooling fan.
    • Controls the hybrid vehicle converter.
    ECM Activates the ETCS-i (Electronic Throttle Control System-intelligent) in accordance with the target engine speed and required engine motive force received from the HV control ECU.
    Battery Smart Unit
    • Monitors the conditions of the HV battery and transmits this information to the HV control ECU.
    • Monitors the fault current of the HV battery.
    Accelerator Pedal Position Sensor Converts the accelerator pedal position into an electrical signal and outputs it to the HV control ECU.
    Park / Neutral Position Switch Converts the shift position into an electrical signal and outputs it to the HV control ECU.
    Hybrid Mode Select Switch Outputs the driving mode (normal, power, or snow mode) that the driver has selected to the HV control ECU via the main body ECU.
    Transmission Control Switch While the vehicle is being driven in the S mode, this switch outputs a signal to the HV control ECU if the shift lever is moved towards "+" or "-".
    HV Relay Assembly Connects and disconnects the high-voltage power circuit between the battery and the inverter with converter assembly, through the use of a signal from the HV control ECU. Contains the SMRB and SMRG.
    Interlock Circuit (for Inverter Cover and Service Plug Grip) Verifies that the cover of both the inverter and the service plug grip have been installed.
    Service Plug Grip Shuts off the high-voltage circuit of the HV battery when this plug grip is removed for vehicle inspection or maintenance.
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