HYBRID CONTROL SYSTEM


  1. OUTLINE


    1. The hybrid system of this hybrid vehicle employs the LEXUS Hybrid Drive under the "Hybrid Synergy Drive" concept*.

      Tech Tips

      *: The "Hybrid Synergy Drive" concept consists of 4 key benefits: Fuel efficiency, low emissions, seamless acceleration, and silent performance.

    2. Hybrid vehicles use a combination of 2 kinds of power sources, such as an engine and HV battery, 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.

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

    4. 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 electric motors.

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

  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 230.4
      DC-DC Converter Rated Output Voltage V DC 11.0 to 15.0
      Maximum Output Current A 120

    2. Cooling System (for Inverter with Converter Assembly and Hybrid Vehicle Transmission Assembly)

      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)

      2.0 (2.1, 1.8)*1

      2.2 (2.3, 1.9)*2
      Maintenance Intervals First Time km (miles) 240000 (150000)
      Subsequent km (miles) Every 80000 (50000)

      *1: LHD Models

      *2: RHD Models

  3. MAIN FEATURES


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

      Item Outline
      Idle Stop 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 Drive Mode If the driver operates the switch and the operating conditions are being met, the vehicle can run on only the electric motor.
      Motor Assist The 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, such as for motor power.

    2. The mechanism of the LEXUS Hybrid Drive is as follows.


      1. The LEXUS Hybrid Drive consists of mainly the engine, hybrid vehicle transmission assembly, inverter with converter assembly and HV battery, and employs a series/parallel-type hybrid system.

        A01MR53C02
        *1 Engine *2 Hybrid Vehicle Transmission Assembly
        *3 Power Split Planetary Gear Unit (Compound Gear Unit) *4 Motor Speed Reduction Planetary Gear Unit (Compound Gear Unit)
        *5 Generator (MG1) *6 Motor (MG2)
        *7 Inverter with Converter Assembly *8 Differential
        *9 HV Battery - -
        A001ZMG Mechanical Power Path A001ZDI Electrical Power Path (AC)
        B003XNF Electrical Power Path (DC) - -

        Tech Tips

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


        • In a series-type hybrid system, the motor rotates the wheels, and the engine, using a generator, acts as an electric power source for the motor.

          A01MRB9C02
          *1 Engine *2 Generator
          *3 Inverter *4 HV Battery
          *5 Motor - -
          A001ZMG Electrical Power Path (DC) A001ZDI Electrical Power Path (AC)
          B003XNF Mechanical Power Path - -

        • In a parallel-type hybrid system, both the engine and the motor generator directly rotate the wheels. In addition to supplementing the power of the engine, the motor generator can also serve as a generator to charge the HV battery while the vehicle is in motion. Driving the vehicle only with the motor generator is also possible.

          A01MR6VC02
          *1 Engine *2 Transmission
          *3 HV Battery *4 Inverter
          *5 Motor Generator - -
          A001ZMG Electrical Power Path (DC) A001ZDI Electrical Power Path (AC)
          B003XNF Mechanical Power Path - -

        • In a series/parallel-type hybrid system, aspects 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 generator (MG1) using engine power. The generated electricity is used to charge the HV battery and also to power motor (MG2).

          A01MRCUC02
          *1 Engine *2 Power Split Planetary Gear Unit
          *3 HV Battery *4 Inverter
          *5 Generator (MG1) *6 Motor (MG2)
          A001ZMG Electrical Power Path (DC) A001ZDI Electrical Power Path (AC)
          B003XNF Mechanical Power Path - -

      2. This system optimally performs cooperative control of the 2AR-FSE engine, and generator (MG1) and motor (MG2) in the L210 hybrid vehicle transmission assembly that provides excellent transmission performance.

      3. The system has 2 batteries, which are used for different purposes. One is the HV battery (nominal voltage of DC 230.4 V) which stores electrical power to drive the vehicle, and the other is the auxiliary battery (nominal voltage of DC 12 V) which supplies electrical power to the electrical components.

      4. Furthermore, it uses a variable-voltage system consisting of the high-output HV battery (nominal voltage of DC 230.4 V), a boost converter that boosts the operating voltage of generator (MG1) and motor (MG2) to a maximum voltage of DC 650 V, and an inverter which 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 stepped down to approximately DC 14 V using a DC-DC converter in order to charge the auxiliary battery. Also, the HV battery regularly charges and discharges within the constant State of Charge (SOC) range while the vehicle is running, thus, recharging from external power sources is not necessary.

        A01MRFJC01
        *A RHD Models *B LHD Models
        *1 2AR-FSE Engine *2

        L210 Hybrid Vehicle Transmission Assembly


        • Generator (MG1)

        • Motor (MG2)
        *3

        Inverter with Converter Assembly


        • Inverter

        • Boost Converter

        • DC-DC Converter

        		 *4 HV Battery Assembly
        *5 Auxiliary Battery - -

      6. 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).

        Figure 1. RHD Models

        A01MRBIC02
        *1 Inverter Reserve Tank *2 Inverter Water Pump Assembly
        *3 Radiator Assembly *4 Inverter with Converter Assembly
        B003XLG HV Coolant Flow - -

        Figure 2. LHD Models

        A01MRGQC02
        *1 Inverter Reserve Tank *2 Inverter Water Pump Assembly
        *3 Radiator Assembly *4 Inverter with Converter Assembly
        B003XLG HV Coolant Flow - -

  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, inverter with converter assembly, hybrid vehicle transmission assembly and compressor with motor assembly. Each of these items is connected by the power cable (frame wire) and is electrically insulated using cases and covers.

      2. The power cable (frame wire) is 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 its main purpose is to prevent electromagnetic interference.

        A01MR8IC01
        *A RHD Models *B LHD Models
        *1 Hybrid Vehicle Transmission Assembly *2 Service Plug Grip
        *3 Compressor with Motor Assembly *4 Inverter with Converter Assembly
        *5 Power Cable (Frame Wire) *6 HV Battery Assembly

    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 power management control ECU.


        • Power switch is off.

        • Any airbag is deployed.

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

        • Connector cover assembly is removed (interlock circuit is opened).

        • Power cable connector is disconnected (interlock circuit is opened).

        • Service plug grip handle is unlocked (interlock circuit is opened).

        • A specified malfunction occurs.

        A01MR61E03