HYBRID CONTROL SYSTEM


  1. OUTLINE


    1. Hybrid vehicles uses a combination of 2 kinds of power sources, such as an engine and electricmotor, so as to take advantage of the benefits provided by each power source while compensating for each other's shortcomings. As a result, efficient operation is achieved.

    2. Hybrid vehicles do not need their batteries to be charged externally unlike existing electric-onlyvehicles. Therefore, special infrastructure is not required to use hybrid vehicles.

    3. Technical development of power units (such as an engine or fuel cell) is advancing in various fields. The hybrid system is a flexible system that uses a high-efficiency power unit and electricmotors.

    4. Hybrid vehicles have high-voltage electrical circuits. Hybrid vehicles have been developed with consideration given to the protection of drivers and technicians against electrocution.

    5. This hybrid vehicle uses LEXUS Hybrid Drive to drive the front wheels and adds the E-Four system to drive the rear wheels.*

      Tech Tips

      *: AWD models

  2. SPECIFICATION


    1. Inverter with Converter Assembly

      Item Specification
      Boost Converter Rated Voltage (Inverter Side) V DC 650
      Rated Voltage (HV Battery Side) V DC 288 V
      DC-DC Converter Rated Output Voltage V DC11.5, DC 13.0 to 14.5
      Maximum Output Current A 150

    2. Cooling System

      Item Specification
      Inverter Water Pump Assembly Motor Type Brushless
      Discharge Volume Liter (US qts, Imp. qts) 12 (12.7, 10.6) /min. or greater
      Coolant Type Toyota Genuine Super Long Life Coolant (SLLC)
      Color Pink
      Capacity Liter (US qts, Imp. qts) 1.9 (2.0, 1.7)
      Maintenance Intervals First Time km (miles) 240000 (150000)
      Subsequent km (miles) Every 80000 (50000)

    3. Auxiliary Battery

      Size (Width x Height x Thickness) 241 mm X 189 mm X 174 mm
      Rated Voltage 12 V
      Battery Capacity (20HR) 62 Ah

  3. MAIN FEATURES


    1. The LEXUS Hybrid Drive control has the following features.

      Features Outline
      Idle Stop (Reduction of Energy Loss) Idling of the engine is automatically stopped (idle stop) to reduce energy loss.
      EV Drive (Efficient Drive Control) This allows the vehicle to be driven using only the electric motor when engine efficiency is low. In addition, electricity is generated when engine efficiency is high. Control is performed to maximize the total efficiency of the vehicle.
      EV Mode If the driver operates the switch and the operating conditions are met, the vehicle can run on only the electric motor.
      Motor Assist An electric motor supplements the engine power when accelerating.
      Regenerative Braking (Energy Regeneration) During deceleration and while depressing the brake pedal, part of the energy that was lost as heat is collected as electrical energy to be reused, for example as motor power.

    2. The E-Four system has the following features:

      Features Outline
      Ensures Traction Performance The E-Four system achieves an appropriate level of start-off stability and acceleration on snow-covered or other slippery road surfaces.
      Ensures Fuel Efficiency The E-Four system usually uses the front wheel drive only in order to ensure fuel economy. Using Motor Generator Rear (MGR), it distributes motive force to the rear wheels in accordance with driving conditions.

    3. Generally, there are 3 types of hybrid systems: a series-type hybrid system, a parallel-type hybrid system and a series/parallel-type hybrid system.


      1. Series-type Hybrid System


        • The motor rotates the wheels, and the engine acts as an electric power source for the motor using a generator.

          A01R2IMC01
          *1 Engine *2 Generator
          *3 Inverter *4 HV Battery
          *5 Motor - -
          A01R2I6 Mechanical Power Path B0055C2 Electrical Power Path (DC)
          A01R2CI Electrical Power Path (AC) - -

      2. Parallel-type Hybrid System


        • Both the engine and the motor directly rotate the wheels. In addition to supplementing the power of the gasoline engine, the electric motor can also serve as a generator to charge the high-voltage battery pack while the vehicle is in motion. Driving the vehicle with the motor only is also possible.

          A01R2BJC01
          *1 Engine *2 Transmission
          *3 HV Battery *4 Inverter
          *5 Motor Generator - -
          A01R2I6 Mechanical Power Path B0055C2 Electrical Power Path (DC)
          A01R2CI Electrical Power Path (AC) - -

      3. Series/Parallel Hybrid System


        • Features of both a series-type hybrid system and a parallel-type hybrid system are combined. The system has 2 motor generators. Electricity can be generated by Motor Generator No. 1 (MG1) using engine power. The generated electricity is used to charge the HV battery and/or also to power Motor Generator No. 2 (MG2).

          A01R25ZC01
          *1 Engine *2 Power Split Planetary Gear
          *3 HV Battery *4 Inverter
          *5 Motor Generator No. 1 (MG1) *6 Motor Generator No. 2 (MG2)
          A01R2I6 Mechanical Power Path B0055C2 Electrical Power Path (DC)
          A01R2CI Electrical Power Path (AC) - -

    4. LEXUS Hybrid Drive aims for a high-level simultaneous pursuit of ecology and power, which embodies the hybrid synergy drive concept.


      1. The LEXUS Hybrid Drive consists of mainly the engine, hybrid transaxle, inverter with converter assembly and HV battery, and employs the series/parallel-type hybrid system. In addition, AWD models use an E-Four system that has a combined rear drive unit and series-type hybrid system.

        A01R2CEC01
        *A AWD Models - -
        *1 Engine *2 Hybrid Transaxle (Hybrid Vehicle Transaxle Assembly)
        *3 Differential *4 Power Split Planetary Gear Unit
        *5 Motor Speed Reduction Planetary Gear *6 Generator (MG1)
        *7 Motor (MG2) *8 Inverter with Converter Assembly
        *9 HV Battery *10 Rear Drive Unit (Rear Traction Motor with Transaxle Assembly)
        *11 Rear Motor (MGR) - -
        *a Mechanical Power Path *b Electrical Power Path (DC)
        *c Electrical Power Path (AC) - -

      2. The LEXUS Hybrid Drive optimally performs cooperative control of the high-output 2GR-FXS engine and the high-speed, high-output Motor Generator No. 1 (MG1) and Motor Generator No. 2 (MG2) in the P314 hybrid transaxle that provides excellent transmission performance. On the AWD models, the E-Four system also controls Motor Generator Rear (MGR) through the Q211 rear drive unit that provides excellent traction performance.

      3. Hybrid vehicles have 2 batteries that are used for different purposes. One is the HV battery (nominal voltage of DC 288 V) that stores electrical power to drive the vehicle, and the other is the auxiliary battery (nominal voltage of DC 12 V) that supplies electrical power to the electrical components.

      4. Furthermore, it uses a variable-voltage system consisting of a high-output HV battery with a nominal voltage of DC 288 V, a boost converter that boosts the operating voltage of the system to a maximum voltage of DC 650 V and an inverter that converts direct current and alternating current.

      5. Since hybrid vehicles are not equipped with a conventional generator, the high voltage from the HV battery is reduced to approximately DC 14 V using the hybrid vehicle converter assembly in order to charge the auxiliary battery.

      6. The HV battery uses sealed Nickel Metal Hydride (Ni-MH) battery cells. This HV battery has a high power density, is lightweight, and it offers longevity to match the characteristics of the LEXUS Hybrid Drive. Because charge/discharge control is performed to maintain the HV battery within a constant State Of Charge (SOC) range while the vehicle is operating normally, it does not require external recharging.

      7. A cooling system that is independent from the engine cooling system is provided to cool the inverter with converter assembly, generator (MG1) and motor (MG2).

        A01R2AUE02
        *1 Inverter with Converter Assembly
        *2 Inverter Radiator
        *3 Inverter Reservoir Tank Assembly
        *4 Inverter Water Pump with Motor Assembly

  4. PRECAUTION


    1. Hybrid Vehicle High-voltage Safety Measures


      1. High-voltage safety is comprised of 2 points: insulation of high-voltage circuits and cut-off of high-voltage circuits. The hybrid system also detects whether or not a decrease in insulation resistance has occurred between the high-voltage system and body ground.

    2. Insulation of High-voltage Circuits


      1. High-voltage circuits are used between the HV battery assembly, inverter with converter assembly, hybrid transaxle, rear drive unit (rear traction motor with transaxle assembly)* and compressor with motor assembly. Each of these items is connected by a power cable and electrically insulated using cases and covers.


        • *: AWD models

      2. Cables are also shielded using a mesh conductor built into the electrical insulation of the wires. The shielding is grounded to the chassis of the vehicle and the main purpose is to prevent electromagnetic interference.


        • A01R2OOC01
          *A AWD Models - -
          *1

          P314 Hybrid Transaxle (Hybrid Vehicle Transaxle Assembly)


          • Motor Generator No. 1 (MG1)

          • Motor Generator No. 2 (MG2)

          		 *2 Service Plug Grip
          *3 Compressor with Motor Assembly *4 Inverter with Converter Assembly
          *5 Power Cable *6 HV Battery Assembly
          *7 DC-DC Converter (Power Steering Converter Assembly) *8

          Q211 Rear Drive Unit (Rear Traction Motor with Transaxle Assembly)


          • Motor Generator Rear (MGR)

    3. Cut-off of High-voltage Circuits


      1. When any of the conditions below occurs, the System Main Relays (SMRs) are automatically shut off by the hybrid vehicle control ECU assembly.


        • Power switch is turned off.

        • Any airbag is deployed.

        • The power cable from the HV battery is removed from the inverter.

        • Inverter terminal cover is removed (interlock circuit is opened).

        • Service plug grip handle is raised partway (interlock circuit is opened)*.

        • A specified malfunction occurs.

          Tech Tips

          *: The service plug grip should never be removed when the vehicle is in the READY-ON state.

      2. The service plug grip is used to cut off the high-voltage circuit manually for when service is to be performed on the vehicle.

        A01R1Y5E02

        CAUTION:

        Regarding discharge of the capacitor in the inverter with converter assembly: a charge remains in the high-voltage capacitor in the inverter with converter assembly after the high voltage circuits are shut down. When servicing a hybrid vehicle, after the service plug grip is removed, wait at least 10 minutes to allow the capacitor in the inverter to discharge before beginning work.