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System Description

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  1. OPERATION 
    1. Operation of EV
      1. The EV control system runs the vehicle by the motor by using the power charged to the electric vehicle battery assembly from the external power source via the electric vehicle charger assembly. The electric vehicle battery assembly is also charged while deceleration by using the motor as a generator.
    2. READY-on State
      1. When the power switch is pressed while depressing the brake pedal, the power management control ECU checks the EV control system and activates it.
    3. When moving forward
      1. The vehicle travels by driving the motor using the power from the electric vehicle battery assembly.
        Fig 1: Identifying READY-On State Chart
        GTY390773Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
        TEXT IN ILLUSTRATION

        *1 Motor *2 Motor Speed Reduction Planetary Gear Unit
        *3 Inverter with Converter Assembly *4 Electric Vehicle Battery Assembly
        Electrical Power Path (DC) Electrical Power Path (AC)
        Mechanical Power Path - -
    4. When decelerating or stopping.
      1. When decelerating (accelerator off), the power is generated by the rotation of the motor by the power transmitted from the wheels, and the electrical energy converted from dynamic energy will be collected to the electric vehicle battery assembly.
      2. When stopping, the power management control ECU determines the amount of energy to be recovered to the battery by operating in harmony with the electronically controlled brake system in order to achieve optimum braking force in accordance with the brake pedal operation amount.
        Fig 2: Identifying Decelerating Or Stopping Chart
        GTY385205Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
        TEXT IN ILLUSTRATION

        *1 Motor *2 Motor Speed Reduction Planetary Gear Unit
        *3 Inverter with Converter Assembly *4 Electric Vehicle Battery Assembly
        Electrical Power Path (DC) Electrical Power Path (AC)
        Mechanical Power Path - -
    5. During Reverse
      1. When traveling in reverse, the vehicle moves rearward by making the motor rotate in the reverse direction from when moving forward, using the electrical supply from the electric vehicle battery assembly.
        Fig 3: Identifying During Reverse Chart
        GTY385895Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
        TEXT IN ILLUSTRATION

        *1 Motor *2 Motor Speed Reduction Planetary Gear Unit
        *3 Inverter with Converter Assembly *4 Electric Vehicle Battery Assembly
        Electrical Power Path (DC) Electrical Power Path (AC)
        Mechanical Power Path - -
  2. SYSTEM DIAGRAM 
    Fig 4: Electrical Vehicle System Diagram (1 Of 2)
    GTY392101Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 5: Electrical Vehicle System Diagram (2 Of 2)
    GTY392075Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. FUNCTION OF MAIN COMPONENTS 
    1. The main components of the EV system have the following functions:
      Component Function
      Power Management Control ECU
      1. Performs comprehensive control of the EV control system.
        • Information from various sensors as well as from ECUs (MG ECU, battery voltage sensor and skid control ECU) is received, and based on this the required torque and output power is calculated. The power management control ECU transmits the calculated result to the MG ECU and skid control ECU.
        • Monitors the SOC of the electric vehicle battery assembly.
        • Controls the DC-DC converter.
        • Controls the water pump with motor assembly.
        • Controls the battery cooling blower assembly.
      2. Activates the SMR and shuts off the power to the high voltage circuit upon receiving the airbag deployment signal from the airbag ECU assembly.
      EV Transaxle with Motor Assembly Motor (MG2)
      • Motor, which is driven by electrical power from the electric vehicle battery assembly, generates motive force for the drive wheels.
      • During braking, or when the accelerator pedal is not depressed, it generates high-voltage electricity to recharge the electric vehicle battery assembly.
      Motor Resolver Detects the rotor position, rotational speed and direction of motor.
      Motor Temperature Sensor Detects the temperature of motor.
      Motor Speed Reduction Planetary Gear Unit Reduces the rotational speed of motor in accordance with the characteristics of the planetary gear, in order to increase torque.
      Inverter with Converter Assembly Inverter Converts the direct current from the electric vehicle battery assembly into alternating current for motor, and vice versa (from AC to DC).
      DC-DC Converter Steps down the electric vehicle battery assembly nominal voltage of DC 277.5 V to approximately DC 14 V in order to supply electricity to the electrical components, as well as to recharge the auxiliary battery.
      MG ECU Controls the inverter in accordance with the signals received from the power management control ECU.
      Temperature Sensor for Inverter with Converter Assembly Detects temperatures in the parts of the inverter with converter assembly as well as the EV coolant temperature.
      Inverter Current Sensor Detects the current of motor.
      Plugin Charge Control ECU Stops the EV control system when a charging connector is connected, upon receiving a signal from the charging cable (electric vehicle charger cable assembly) or quick charger charging connector.
      Electric Vehicle Battery Assembly Electric Vehicle Battery Stack Assembly
      • Supplies electrical power to inverter with converter assembly in accordance with the driving conditions of the vehicle.
      • Recharged by motor in accordance with the SOC and the driving conditions of the vehicle.
      • Accumulates power from the external power source supplied by plug-in charging.
      EV Battery Temperature Sensor Detects temperatures in the parts of the electric vehicle battery assembly.
      EV Battery Intake Air Temperature Sensor Detects the intake air temperature from the battery cooling blower assembly.
      EV Battery Junction Block Assembly System Main Relay (SMR) Connects and disconnects the high-voltage circuit between the electric vehicle battery assembly and the inverter with converter assembly through the use of signals from the power management control ECU.
      Battery Current Sensor Detects the input and output current of the electric vehicle battery assembly.
      Service Plug Grip Service plug grip shuts off the high-voltage circuit of the electric vehicle battery assembly when the service plug grip is removed for vehicle inspection or maintenance.
      Battery Voltage Sensor
      • Monitors the conditions of the electric vehicle battery assembly such as voltage, current and temperature, and transmits this information to the power management control ECU.
      • Monitors the high-voltage system for breakdown of the electrical insulation.
      Interlock Switch (for Service Plug Grip / for Upper Inverter Cover Sub-Assembly / for Frame Wire Connector (To Inverter with Converter Assembly) Verifies that the service plug grip, upper inverter cover sub-assembly, and frame wire connector (to inverter with converter assembly) are installed.
      Power Cable (Frame Wire) Connects the electric vehicle battery assembly, inverter with converter assembly, EV transaxle with motor assembly and electric inverter compressor (compressor with motor assembly).
      Water Pump with Motor Assembly Operates under the control of the power management control ECU in order to cool the inverter with converter assembly.
      Battery Cooling Blower Assembly Operates under the control of the power management control ECU in order to cool the electric vehicle battery assembly.
      Auxiliary Battery Supplies electricity to the electrical components when the EV control system is stopped.
      Auxiliary Battery Temperature Sensor (Thermistor Assembly) Detects the temperature of the auxiliary battery.
      Power Switch Starts and stops the EV control system.
      Accelerator Pedal Sensor Assembly Converts the accelerator pedal position into an electrical signal and sends it to the power management control ECU.
      Shift Lever Position Sensor Detects the shift lever position (P, R, N, D and B) and transmits signals to the power management control ECU.
      Transmission Control Switch Detects the shift lever position (S) and transmits signals to the power management control ECU.
      1. Brake Booster with Master Cylinder Assembly
        • Skid Control ECU
      • During braking, it calculates the required regenerative braking force and transmits it to the power management control ECU.
      • Transmits the request to the power management control ECU to limit motive force while the TRC or VSC is operating.
      Airbag ECU Assembly During a collision, it transmits the airbag deployment signal to the power management control ECU.
      Combination Meter Assembly READY Indicator Light Informs the driver that the vehicle is ready to drive.
      Plug-in Indicator Illuminates green when the charging cable is connected, and flashes yellow in case a malfunction occurs.
      Output Control Warning Light Illuminates or flashes if the motor output is restricted when the electric vehicle battery assembly capacity has decreased or to protect the EV control system.
      Eco Driving Indicator Illuminates when the driver's acceleration operation is eco-friendly (during Eco Driving).
      Master Warning Light Illuminates or flashes depending on the problem when a system malfunction occurs. A message is also displayed on the multi-information display.
      State Of Charge (SOC) Warning Light Illuminates or flashes depending on the remaining battery charge when the electric vehicle battery assembly capacity is low.
      Low Traction Battery Indicator Light Illuminates to inform the driver that the electric vehicle battery assembly must be inspected.
      Auxiliary Battery Warning Light Turns on when there is a malfunction in the auxiliary battery charging system.
      Multi-information Display
      • The multi-information display displays messages to inform the driver when a malfunction occurs. It also displays system status and operation instructions.
      • The multi-information display displays the drivable distance and the remaining power in the electric vehicle battery assembly.
      • The EV control system indicator displays the conditions of the electrical power output from the EV control system.
      Buzzer When a system malfunction occurs, a warning message is displayed on the multi-information display and the buzzer sounds simultaneously in accordance with the problem.
  4. REGARDING DIAGNOSTIC PROCEDURE FOR DTC OUTPUT 
    NOTE:

    This flowchart is intended to give an overview of the diagnostic flow when P307F-123 is output. For specific instructions, follow the diagnostic procedure for the particular DTC to perform malfunction diagnosis.

    Fig 6: Identifying Diagnostic Flow When P307F-123 Is Output
    GTY390638Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. If at least one of the two parallel EV battery packs has an EV battery system malfunction, in addition to the DTC showing the contents of the malfunction, the EV control system DTC P307F-123 may also be output at the same time.
    2. When DTC P307F-123 is output, the power management control ECU judges that at least one of the two parallel EV battery packs has an EV battery system malfunction, and as a fail-safe the + side SMR of the malfunctioning pack is disconnected, so that the remaining battery pack can be used to drive the vehicle in fail-safe driving mode.
    3. After driving with only one battery pack, resulting in the two battery pack voltages becoming unbalanced, if the fail-safe driving history is cleared and the power switch is turned on (READY), overcurrent will flow between the No. 1 EV battery and No. 2 EV battery, and the high voltage fuse inside the electric vehicle battery assembly may blow.
    4. To prevent this, first perform the diagnostic procedure for the DTC that caused DTC P307F-123 to be stored, and repair or replace the malfunctioning part(s).
    5. Next, perform the No. 1 EV battery - No. 2 EV battery voltage difference inspection. Refer to No. 1 EV Battery - No. 2 EV Battery Voltage Difference Inspection and then if the result is less than the specified value, perform the Utility "Battery Pack Malf Fail-Safe Drive History Clear". Refer to UTILITY  and clear the DTCs.
    6. If the result of No. 1 EV battery - No. 2 EV battery voltage difference inspection is greater than the specified value, replace the electric vehicle battery assembly, perform Utility "Battery Pack Malf Fail-Safe Drive History Clear". Refer to UTILITY  and clear the DTCs.
    7. If the result of malfunction diagnosis for the DTC that caused DTC P307F-123 to be stored indicates that the power management control ECU was the malfunctioning part, do not replace it immediately. First perform the No. 1 EV battery - No. 2 EV battery voltage difference inspection and confirm that the battery voltage difference between both batteries is less than the specified value, then replace the power management control ECU.
    8. Because the battery pack malfunction fail-safe driving history information is stored in the EEPROM (memory that will not be erased even if the battery cable is removed) of the power management control ECU, replacing the power management control ECU before performing the No. 1 EV battery - No. 2 EV battery voltage difference inspection will cause the battery pack malfunction fail-safe driving history to be erased while the battery voltages of both battery packs are still in an unbalanced state, which can result in overcurrent flowing between the No. 1 EV battery and No. 2 EV battery, and cause the high voltage fuse to blow.
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