HYBRID CONTROL SYSTEM

Hybrid Vehicle Control

1. The hybrid vehicle control ECU detects the amount of accelerator pedal depression using the signals from the accelerator pedal position sensor. The hybrid vehicle control ECU receives vehicle speed signals from the MG2 resolver and detects the shift position signal from the shift lever position sensor. The hybrid vehicle control ECU determines the vehicle operating conditions in accordance with this information, and optimally controls the motive forces of MG1, MG2 and the engine. Furthermore, the hybrid vehicle control ECU optimally controls the output and torque of MG1, MG2 and the engine in order to achieve lower fuel consumption and cleaner exhaust emissions.

2. The hybrid vehicle control ECU calculates the engine motive force based on the calculated target motive force, and by taking the State Of Charge (SOC) and the temperature of the HV battery into consideration. The value obtained by subtracting the engine motive force from the target motive force is the MG2 motive force.

3. The ECM appropriately performs ETCS-i control, fuel injection volume control, ignition timing control and Dual VVT-i system control based on signals sent by the hybrid vehicle control ECU in order to achieve the required engine motive force. Furthermore, the hybrid vehicle control ECU appropriately operates the MG1 and MG2 in order to achieve the required MG2 motive force.

4. The 2-stage motor speed reduction planetary gear is switched to the low-speed range or high-speed range by driving solenoid valves SL1 and SL2 in accordance with the driver's required motive force, HV battery conditions, ATF temperature, vehicle speed, etc.

   

State Of Charge (SOC) Control

1. The hybrid vehicle control ECU calculates the State Of Charge (SOC) of the HV battery by estimating its charging and discharging amperages, in order to control the SOC. This allows the hybrid system to make control decisions based on the power stored in the battery.

2. While the vehicle is in motion, the HV battery undergoes repetitive charge/discharge cycles as it becomes discharged by MG2 during acceleration and charged by regenerative braking during deceleration. The hybrid vehicle control ECU calculates the SOC based on the amount of HV battery charge/discharge detected by the HV battery current sensor. The hybrid vehicle control ECU constantly performs charge/discharge control based on the calculated SOC value in order to maintain the SOC within its target range.

   

Inverter Coolant Cooling Control

1. The hybrid vehicle control ECU receives the signals from the temperature sensors for inverter with converter assembly, temperature sensor for MG1 and temperature sensor for MG2. Then, the hybrid vehicle control ECU actuates the inverter water pump with motor assembly, in order to cool the inverter coolant.

2. When the inverter coolant temperature rises above a certain level, the hybrid vehicle control ECU transmits a radiator fan drive request signal to the cooling fan ECU via the ECM. In response to that signal, the cooling fan ECU actuates the radiator fan to restrain the increases in the inverter coolant temperature, ensuring the cooling of the inverter with converter assembly, MG1 and MG2.

3. The MG ECU converts the temperature sensor signals into digital signals, and transmits them to the hybrid vehicle control ECU via serial communication.

   

HV Battery Cooling Control

1. The HV battery cooling control is performed by utilizing air in the cabin and cool air from the rear air conditioning unit.

2. The hybrid vehicle control ECU calculates the amount of air required to cool down the HV battery module based on the HV battery module temperature and controls the battery cooling blower assemblies to provide air to the HV battery module. At this time, the hybrid vehicle control ECU activates the rear air conditioning unit and mode control damper for the HV battery based on the air conditioning system operating status and battery load conditions to provide cool air to the HV battery module. The rear air conditioning unit operates when the following conditions are satisfied:

   
   

   • When the air conditioning system is operating: activates when the battery loads exceed the prescribed value within the predetermined period.

   • When the air conditioning system is not operating: activates when the battery load exceeds the prescribed value within the predetermined period, and when high temperature situations occur more times than the prescribed limit.

3. The hybrid vehicle control ECU decreases the speed of battery cooling blower assemblies when the rear air conditioning unit is operating to suppress the air flow from the blower, reducing the noise in the cabin.

4. When the air conditioning system is not operating, if the rear air conditioning unit is operated by the hybrid vehicle control ECU, the air conditioning amplifier assembly informs the driver that the rear air conditioning unit is operating by displaying the message "Climate Control activated to cool Hybrid System" on the multi-information display.

5. While the air conditioning system is operating to cool the cabin, if the HV battery module temperature is within a normal range, the hybrid vehicle control ECU turns the battery cooling blower assemblies off or sets them to a low speed. The purpose of this control is to give priority to cooling down the cabin, which also cools the battery module through the intake duct located on the rear package tray trim.

   

Auxiliary Battery Charging Control

1. The hybrid vehicle control ECU controls the hybrid vehicle converter in accordance with the signals from the auxiliary battery temperature sensor (thermistor assembly), in order to control the charging voltage to the auxiliary battery.

   

ECM Control

1. The ECM receives the target engine speed and required engine motive force which were sent from the hybrid vehicle control ECU, and controls the ETCS-i system, fuel injection volume, ignition timing and Dual VVT-i system.

2. The ECM transmits information about the engine operating conditions to the hybrid vehicle control ECU.

3. Upon receiving an engine stop signal from the hybrid vehicle control ECU in accordance with basic hybrid vehicle control, the ECM will stop the engine.

4. When a malfunction occurs in the system, the ECM activates the MIL via the directions from the hybrid vehicle control ECU.

   

MG1 and MG2 Main Control

1. MG1, which is driven by the engine, generates high voltage electricity (alternating current) in order to power MG2 and charge the HV battery. Also, MG1 functions as a starter to start the engine.

2. MG2 is driven by electrical power from the HV battery and/or MG1, and it generates motive force for all the wheels.

3. MG2 generates electricity to charge the HV battery during braking (regenerative braking control), or when the accelerator pedal is not being depressed.

4. The Motor Generator ECU (MG ECU), which follows the commands of the hybrid vehicle control ECU, controls MG1 and MG2 via the Intelligent Power Modules (IPMs) for driving the vehicle. 6 Insulated Gate Bipolar Transistors (IGBTs) switch on and off to control each individual motor generator in accordance with operation as either a motor or a generator.

5. The illustration below describes the basic control when a motor generator functions as a motor.

   
   

   1. The IGBTs switch on and off to supply 3-phase alternating current to the motor.

   2. In order to create the motive force required by the motor generator as calculated by the hybrid vehicle control ECU, the MG ECU switches the IGBTs on and off and controls the speed, in order to control the speed of the motor generator.

      

      *1	Motor Generator
      *2	On

6. The illustration below describes the basic control used when a motor generator functions as a generator.

   
   

   1. The current that is generated sequentially by the 3 phases of the motor, which is driven by the wheels, is utilized to charge the HV battery or drive another motor generator.

      

      *1	Motor Generator

Inverter Control

1. The inverter converts the direct current from the HV battery into alternating current for MG1 and MG2, or vice versa, in accordance with the signals provided by the hybrid vehicle control ECU via the Motor Generator ECU (MG ECU). In addition, the inverter takes power generated by MG1 and supplies it to MG2. However, the electricity generated by MG1 is converted into direct current inside the inverter before being converted back into alternating current by the inverter for use by MG2. This is necessary because the frequency of the alternating current output by MG1 is not appropriate for control of MG2.

2. Via the MG ECU, the hybrid vehicle control ECU transmits signals to the power transistors in the inverter for switching the U, V and W phases of stator coils of MG1 and MG2 based on the rotor position information sent by the MG1 and MG2 resolvers.

3. When the shift lever is in N or when the hybrid vehicle control ECU has received an over-heating, over-current or fault voltage signal from the inverter, the hybrid vehicle control ECU transmits a shut down control signal to the inverter in order to turn off the power transistors to electrically disconnect MG1 and MG2.

   

Boost Converter Control

1. The boost converter boosts the HV battery nominal voltage of DC 288 V up to a maximum voltage of DC 650 V in accordance with the signals provided by the hybrid vehicle control ECU via the Motor Generator ECU (MG ECU).

   

2. The inverter converts the alternating current generated by MG1 or MG2 into direct current. The boost converter drops the voltage from DC 650 V (maximum) to DC 288 V (nominal) for the HV battery in accordance with the signals provided by the hybrid vehicle control ECU via the Motor Generator ECU (MG ECU).

   

3. The boost converter consists of a reactor and a boost Intelligent Power Module (IPM) with built-in Insulated Gate Bipolar Transistors (IGBTs) that perform switching control.

4. The reactor is an electronic component that has characteristics that resist changes in current flow. If a circuit containing a reactor is switched on and then off, the reactor will attempt to maintain current flow after being switched off. At the time of voltage reduction, these characteristics also assist in smoothing the output from the voltage drop IGBT (1). The reactor can be charged quickly by turning on the boost IGBT (2).

   

   *a	Boost IPM
   *b	Inverter
   *c	Reactor
   *d	HV Battery

5. The boost converter boosts the HV battery voltage from DC 288 V (nominal) to a voltage of up to DC 650 V as described in the following 2 steps:

   
   

   1. The IGBT (2) turns on, causing the electrical power of the HV battery (nominal voltage of DC 288 V) to charge the reactor. As a result, the reactor stores power.

      

   2. The IGBT (2) turns off, causing the reactor to produce an electromotive force (the current continues to flow from the reactor). This electromotive force causes the voltage to rise to a maximum of DC 650 V.

      

6. The alternating current which is generated by MG1 or MG2 for the purpose of charging the HV battery is converted into direct current (maximum voltage approximately 650 V) by the inverter. Then, the boost converter is used to drop the voltage to approximately DC 288 V. This is accomplished by IGBT (1) being switched on and off using duty cycle control, intermittently interrupting the electrical power provided to the reactor by the inverter.

   

Hybrid Vehicle Converter Control

1. The hybrid vehicle converter drops the HV battery nominal voltage of DC 288 V to approximately DC 14 V in order to supply electricity to the electrical components, as well as to recharge the auxiliary battery.

2. In order to regulate the output voltage from the hybrid vehicle converter, the hybrid vehicle control ECU transmits the output voltage request signal to the hybrid vehicle converter in response to the auxiliary battery temperature sensor (thermistor sensor) signals.

   

Battery Voltage Sensor Control

1. The battery voltage sensor detects and transmits the HV battery condition signals (voltage, current and temperature), which are used to determine charging or discharging values, to the hybrid vehicle control ECU.

2. The battery voltage sensor also detects and transmits the battery cooling blower assembly voltage signals, which are necessary to effect HV battery cooling control, to the hybrid vehicle control ECU.

3. A leak detection circuit is provided in the battery voltage sensor in order to detect any excessive current draw from the HV battery.

   

Skid Control ECU Assembly Control

1. The skid control ECU calculates the total brake force needed based on the master cylinder pressure in the brake actuator and brake pedal stroke sensor signal generated when the driver depresses the brake pedal.

2. After calculating the total brake force required, the skid control ECU sends a regenerative braking force request to the hybrid vehicle control ECU. The hybrid vehicle control ECU replies with the amount of regenerative braking force that is possible.

3. The hybrid vehicle control ECU uses MG2 to create minus torque (deceleration force), thus carrying out the regenerative braking.

4. The skid control ECU controls the brake actuator and generates wheel cylinder pressure. The pressure that is generated is what remains after the actual regenerative braking control value has been subtracted from the total required brake force.

5. The skid control ECU outputs a request to the hybrid vehicle control ECU to limit motive force while the TRC or VSC is operating to control wheel spin. The hybrid vehicle control ECU controls the engine, MG1 and MG2 in accordance with the present driving conditions in order to suppress the motive force.

   

During Collision Control

1. If the vehicle encounters one of the situations described below, the hybrid vehicle control ECU will shut down the power supply by turning the System Main Relays (SMRs) off for safety.

2. The hybrid vehicle control ECU receives an airbag deployment signal from the center airbag sensor assembly during a frontal collision, side collision or rear side collision.

   

SNOW Mode Control

1. The SNOW mode can be selected by operating the SNOW mode switch.

2. When the SNOW mode is selected, the hybrid vehicle control ECU improves starting-off performance and acceleration performance on slippery road surfaces such as snow on which the wheels may spin by controlling to restrain motive force more than when in NORMAL mode.

3. When SNOW mode control is activated, the motive force that changes in accordance with the accelerator pedal operation is controlled to be smaller than NORMAL mode around the accelerator pedal angle which causes the wheels to slip easily, achieving enhanced accelerator pedal controllability.

   

Resolver

1. A resolver is an extremely reliable and compact sensor that precisely detects the magnetic pole position. Knowing the precise position of the magnetic poles of the motor rotor is indispensable for ensuring efficient control of MG1 and MG2. MG1 and MG2 each have their own resolver.

2. The stator of the resolver contains 3 types of coils: excitation coil A, detection coil S and detection coil C.

3. The rotor of the resolver is oval, the distance of the gap between the stator and the rotor varies with the rotation of the rotor.

4. The flow of alternating current into excitation coil A results in the creation of a constant frequency magnetic field. Using this constant frequency magnetic field, coils S and C will output values that correspond to the position of the rotor. Therefore, the Motor Generator ECU (MG ECU) detects the absolute position based on the difference between the coil S and coil C output values. Furthermore, the MG ECU calculates the rotational speed based on the amount of change in the position within a given length of time.

5. The +S and -S pairs of the detection coil S are staggered by 90 degrees. The +C and -C pairs are also staggered in the same way. The C and S pairs of coils are located 45 degrees from each other.

   

   Text in Illustration

   *1	+S (Detection Coil S)	*2	+C (Detection Coil C)
   *3	-S (Detection Coil S)	*4	-C (Detection Coil C)
   *5	Excitation Coil A	*6	Rotor
   *a	Image of Resolver Internal Construction	*b	Electrical Orientation of Resolver Coils
   *c	Circuit of Detection Coil S	*d	Circuit of Detection Coil C

6. Because the excitation coil of the resolver is provided with alternating current at a constant frequency, a constant frequency magnetic field is output to coils S and C, regardless of rotor speed. The magnetic field of the excitation coil is carried to coils S and C by the rotor. The rotor is oval, and the gap between the stator of the resolver and the rotor varies with the rotation of the rotor. Due to the variation of the gap, the peak values of the waveforms output by coils S and C vary in accordance with the position of the rotor.

7. The MG ECU constantly monitors these peak values and connects them to form a virtual waveform. The MG ECU calculates the absolute position of the rotor from the difference between the values of coils S and C. The MG ECU determines the rotor direction based on the difference between the phases of the virtual waveform of coil S and the virtual waveform of coil C. Furthermore, the MG ECU calculates the rotational speed based on the amount of change in the rotor position within a given length of time.

8. The diagrams below illustrate the waveforms that are output at coils A, S and C when the rotor makes a rotation of 180°:

   

   *1	Excitation Coil A
   *2	Detection Coil S
   *3	Virtual Waveform
   *4	Detection Coil C

Temperature Sensor for Motor Generator

1. Temperature sensors are used to detect the temperature of the motor stators.

2. The temperature sensor thermistor resistance changes in accordance with the change of the motor temperature. The resistance of the thermistor is high when the temperature of the motor is low. Conversely, when the motor temperature is high, the thermistor resistance will be low.

3. When the temperature of a motor rises, motor output is limited.

   

   *1	Characteristics of Temperature Sensor
   *2	Resistance
   *3	Temperature

Inverter with Converter Assembly

1. The inverter with converter assembly has a multi-layer structure which consists of the Motor Generator ECU (MG ECU), inverter, boost converter and condenser, achieving a lightweight and compact design.

2. A boost converter and inverter have been integrated into one unit and included in the inverter with converter assembly in order to boost the nominal voltage output by the HV battery from DC 288 V to the maximum voltage of DC 650 V. After the voltage is boosted, the inverter converts the direct current into an alternating current.

3. The inverter with converter assembly is cooled by the dedicated radiator of a cooling system that is separate from that of the engine cooling system.

4. An Insulated Gate Bipolar Transistor (IGBT) is used in the power transistor employed in each Intelligent Power Module (IPM). The dual side cooling structure is used to cool the IGBT, thus efficiently removing the heat generated when the system is operating. In addition, the inverter with converter assembly has been made more compact due to this structure.

   

   Text in Illustration

   *1	Motor Generator ECU (MG ECU)	*2	Boost Converter and Inverter
   *3	Condenser Portion	-	-

   

Inverter

1. The inverter converts the boosted high-voltage direct current of the HV battery into 3-phase alternating current to drive MG1 and MG2.

2. The activation of the power transistors is controlled by the hybrid vehicle control ECU via the Motor Generator ECU (MG ECU). In addition, the inverter transmits information that is needed for current control, such as the output amperage or voltage, to the hybrid vehicle control ECU via the MG ECU.

3. The power transistors used in the inverter are Insulated Gate Bipolar Transistors (IGBTs).

4. Each of the bridge circuits for MG1 and MG2 contains 6 IGBTs, mounted on the high voltage and high current module portion of an Intelligent Power Module (IPM). In addition, a signal processor/protective function processor has been integrated into the control portion of the IPM. The IPM is used to operate the power transistors based on signals from the MG ECU.

   

   *1	Inverter Current Sensor
   *2	IPM for MG1
   *3	IPM for MG2
   *4	Inverter

Boost Converter

1. The boost converter boosts the nominal voltage of DC 288 V that is output by the HV battery to a maximum voltage of DC 650 V. The boost converter consists of a boost Intelligent Power Module (IPM) with a pair of built-in Insulated Gate Bipolar Transistors (IGBTs) which perform switching control, and a reactor which acts as an inductor. By using these components, the converter boosts the voltage.

2. When MG1 or MG2 acts as a generator, the inverter converts the alternating current (maximum voltage of 650 V) into DC, and then the boost converter reduces the voltage to a nominal voltage of DC 288 V, thus charging the HV battery.

   

Inverter Temperature Sensor

1. In the inverter with converter assembly, there are 5 different temperature sensors: 1 sensor for the coolant temperature, 2 for the boost converter and 1 each for the Intelligent Power Modules (IPMs) for MG1 and MG2. The Motor Generator ECU (MG ECU) confirms the effectiveness of the inverter cooling system based on the temperature information sent from these sensors. In addition, inverter output is limited when the temperature is high.

   

Inverter Water Pump with Motor Assembly

1. A compact and high output type electric water pump is used.

2. A high output DC motor (brushless type) is used for the pump motor. Furthermore, bearings that support the motor shaft at both ends are employed, thus suppressing noise and vibration.

   

   Text in Illustration

   *1	Blade	*2	Bearing
   *3	Magnet	*4	Control Circuit
   *5	Coil	*6	Shaft
   	Coolant Inlet		Coolant Outlet

Power Cable

1. The power cable is a set of high-voltage, high-amperage cables that connect the HV battery with the inverter with converter assembly, the inverter with converter assembly with the MG1 and MG2, and the inverter with converter assembly with the compressor with motor assembly. The power cable starts at the connector of the hybrid battery junction block assembly, which is located behind the rear seat. The power cable passes under the floor panel, along the side of the floor reinforcement, and connects to the inverter with converter assembly in the engine compartment.

2. The power cable is made of shielded cables in order to reduce electromagnetic interference.

3. For identification purposes, the high-voltage wiring harness and connectors are color-coded orange to distinguish them from those of the ordinary low-voltage wiring.

   

   Text in Illustration

   *1	Inverter with Converter Assembly	*2	Compressor with Motor Assembly
   *3	Hybrid Vehicle Converter	*4	Battery Cooling Blower Assembly (for Lower Side)
   *5	Battery Cooling Blower Assembly (for Upper Side)	*6	Hybrid Battery Junction Block Assembly
   *7	MG1	*8	MG2
   *9	Power Steering Converter Assembly	*10	Service Plug Grip

HV Battery Assembly

1. The HV battery assembly consists of 2 HV battery module groups, battery voltage sensor, hybrid battery junction block assembly, hybrid battery thermistor, 2 battery cooling blower assemblies, hybrid vehicle converter, converter cooling blower and service plug grip.

2. An upper-and-lower double stack structure is provided for the HV battery module groups and it is located in the luggage compartment behind the rear seat.

3. One battery cooling blower assembly is provided for each of the 2 module groups of the HV battery.

4. A service plug grip is provided to shut off the internal circuit of the battery.

   

   Text in Illustration

   *1	Battery Cooling Blower Assembly (for Upper Side)	*2	Battery Cooling Blower Assembly (for Lower Side)
   *3	Hybrid Battery Thermistor	*4	Service Plug Grip
   *5	Hybrid Battery Junction Block Assembly - SMRG - SMRB - HV Battery Current Sensor	*6	Battery Voltage Sensor
   *7	Hybrid Vehicle Converter - SMRP - Precharge Resistor	*8	Lower HV Battery Module Group
   *9	Converter Cooling Blower	*10	Converter Cooling Blower Controller
   *11	Upper HV Battery Module Group	-	-

HV Battery Module Group

1. The HV battery module groups are split into 2 separate groups inside the battery case.

2. The HV battery module groups are composed of an upper HV battery module group and a lower HV battery module group. The upper HV battery module group consists of 6 modules. The lower HV battery module group consists of 14 modules.

3. The HV battery module groups consist of 20 modules that are connected in series by a bus bar module. Furthermore, the connection between cells is made at 2 locations in order to reduce internal resistance and improve efficiency.

4. The HV battery modules are each made up of 12 cells. 1 cell is 1.2 V. The HV battery has a total of 240 cells (12 cells x 20 modules) and a nominal voltage of 288 V (1.2 V x 240 cells).

5. Metal is used for the material of the module cases to achieve enhanced cooling performance and compact construction.

   

   Text in Illustration

   *1

   Lower HV Battery Module Group (14 Modules)

   *2

   Upper HV Battery Module Group (6 Modules)

Battery Voltage Sensor

1. The battery voltage sensor detects the HV battery condition signals (temperature, voltage and current value) and voltage signals from the battery cooling blower assembly, and sends the signals to the hybrid vehicle control ECU.

   

   Text in Illustration

   *1

   Battery Voltage Sensor

   -

   -

Hybrid Battery Junction Block Assembly

1. A hybrid battery junction block assembly, in which an SMRG, SMRB and HV battery current sensor are integrated, is used.

   

   Text in Illustration

   *1	SMRB (+)	*2	SMRG (-)
   *3	Hybrid Battery Junction Block Assembly	*4	HV Battery Current Sensor

HV Battery Current Sensor

1. The HV battery current sensor is installed on the high-voltage cable inside the HV battery assembly, to detect current flow. The sensor sends a voltage signal to the battery voltage sensor. This signal changes between 0.5 V and 4.5 V in proportion to changes in the current flowing to or from the HV battery assembly. Less than 2.5 V means the HV battery assembly is being discharged, and more than 2.5 V means the HV battery assembly is being charged.

   

Hybrid Battery Thermistor

1. There are 7 hybrid battery thermistor, 3 of them are fitted on the upper battery module group, 3 of them are fitted on the lower battery module group and the remaining one is provided on the intake air duct.

2. The hybrid battery thermistor resistance changes along with the temperature change of the HV battery assembly.

3. The battery voltage sensor transmits the detection results of the hybrid battery thermistor to the hybrid vehicle control ECU, which then controls the battery cooling blower assemblies.

   

   Text in Illustration

   *1

   Hybrid Battery Thermistor

   -

   -

Service Plug Grip

1. The service plug grip is connected to the middle of the battery module circuit and is used to manually shut off the high-voltage circuit.

2. The main fuse for the high-voltage circuit is provided inside of the service plug grip.

3. An interlock switch is provided on the service plug grip. When the grip section is unlocked, the interlock switch is turned off and the hybrid vehicle control ECU shuts off the system main relays. However, to ensure safety, make sure to turn the power switch off before removing the service plug grip.

   

   *1	HV Battery
   *2	Main Fuse
   *3	Interlock Switch
   *4	Service Plug Grip

   Note

   For further details on how to handle the service plug grip and for other safety cautions, refer to the Repair Manual.

Hybrid Vehicle Converter

1. The hybrid vehicle converter is installed in the HV battery unit.

2. The power source for auxiliary equipment of the vehicle such as the lights, audio system and air conditioning system (except the compressor with motor assembly), as well as the ECUs, is based on a DC 14 V system. Because the hybrid system generates output with a nominal voltage of DC 288 V, the hybrid vehicle converter assembly is used to transform the voltage from DC 288 V to approximately DC 14 V in order to recharge the auxiliary battery.

3. A converter cooling blower is provided and is controlled by the converter cooling blower controller.

4. An SMRP is installed in the hybrid vehicle converter.

   

   Text in Illustration

   *1	Hybrid Vehicle Converter - SMRP (Precharge)	*2	Converter Cooling Blower
   *3	Converter Cooling Blower Controller	-	-

   

Power Steering Converter Assembly

1. The power steering converter assembly is located on the upper section of the HV battery unit.

   

   Text in Illustration

   *1

   Power Steering Converter Assembly

   -

   -

2. This converter drops the nominal HV battery voltage from DC 288 V to DC 46 V and supplies electricity to the power steering ECU to activate the EPS system. When the vehicle is equipped with the active stabilizer suspension system, the converter supplies electricity to the front active stabilizer control ECU assembly and rear active stabilizer control ECU assembly.

3. If power supply to the EPS fails, the power steering converter assembly boosts the auxiliary battery voltage from 12 V to 33 V and supplies the voltage to the EPS system.

   

Auxiliary Battery

1. A shielded, maintenance-free DC 12 V battery is used for the auxiliary battery.

2. A battery temperature sensor is mounted on the auxiliary battery.

3. The auxiliary battery is located at the LH side of the luggage compartment.

   

   Text in Illustration

   *1

   Auxiliary Battery Temperature Sensor

   *2

   Auxiliary Battery

Auxiliary Battery Temperature Sensor

1. The battery characteristic (battery internal resistance) of taking in current for charging varies in accordance with battery electrolyte temperature. If the battery electrolyte temperature is too low or too high, the battery will degrade more quickly, resulting in premature failure.

2. To prevent this, the auxiliary battery temperature sensor resistance changes as shown below to allow the hybrid vehicle control ECU to detect the auxiliary battery temperature.

   

   *1	High
   *2	Resistance
   *3	Low
   *4	Battery Temperature

Accelerator Pedal Position Sensor

1. The non-contact type accelerator pedal position sensor uses a Hall IC which is mounted on the accelerator pedal arm.

   

   Text in Illustration

   *1	Hall IC	*2	Magnetic Yoke
   *3	Accelerator Pedal Arm	-	-

2. A magnetic yoke is mounted at the base of the accelerator pedal arm. This yoke rotates around the Hall IC in accordance with the amount of effort that is applied to the accelerator pedal. The Hall IC converts the changes in the magnetic flux that occur into electrical signals, and outputs accelerator pedal position signals to the hybrid vehicle control ECU.

3. The Hall IC contains 2 circuits, one for the main signal, and one for the sub signal. It converts the accelerator pedal position (angle) into electric signals that have differing characteristics and outputs them to the hybrid vehicle control ECU.

   

Driving Condition A: READY-ON State

1. Even if the driver turns the power switch on (READY), sometimes the engine will not start. If this happens, the engine, MG1 and MG2 remain stopped. The engine will only start if conditions such as engine coolant temperature, SOC of the HV battery, HV battery temperature and electrical load require an engine start.

2. After driving, if the driver stops the vehicle and moves the shift lever to P, the hybrid vehicle control ECU will continue to operate the engine. The engine will continue to operate until SOC of the HV battery, engine coolant temperature, HV battery temperature and/or electrical load conditions reach a specified level.

3. If any of the items monitored by the hybrid vehicle control ECU indicates the need for an engine start when the READY indicator light is on and the shift lever is in P, the hybrid vehicle control ECU will activate MG1 to start the engine.

4. While the engine is cranking, to prevent the reactive force of the sun gear of MG1 from rotating the ring gear and driving the drive wheels, current is also applied to MG2 in order to prevent MG2 from rotating. This function is called "reactive control".

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Driven	*b	Drive
   *c	Discharge	-	-
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (DC)		Electrical Power Path (AC)

5. If the SOC of the HV battery is low, it is charged by MG1 which is driven by the engine.

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Drive	*b	Driven - Generates Electricity
   *c	Charged by MG1	-	-
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (DC)		Electrical Power Path (AC)

Driving Condition B: Starting Off

1. When the vehicle is started off, the vehicle operates powered by MG2.

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Stopped	*b	Rotates Freely
   *c	Drive	*d	Discharge
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (DC)		Electrical Power Path (AC)

2. If the SOC of the HV battery is low, it is charged by MG1 which is driven by the engine. The electricity from MG1 is also used to drive MG2.

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Drive	*b	Driven - Generates Electricity
   *c	Charged by MG1	-	-
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (DC)		Electrical Power Path (AC)

Driving Condition C: Running with MG2 and Engine

1. If the required drive torque increases when running with MG2 only, MG1 is activated to start the engine. In addition, if any one of the items monitored by the hybrid vehicle control ECU such as the SOC condition, the battery temperature, the engine coolant temperature or the electrical load condition deviates from the specified level, MG1 is activated to start the engine.

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Driven	*b	Drive
   *c	Discharge	-	-
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (DC)		Electrical Power Path (AC)

Driving Condition D: during Low Load and Constant-speed Cruising

1. When the vehicle is running under low load and constant-speed cruising conditions, the engine will be operated in its most efficient range to power the vehicle. The motive force from the engine is split into two in the power split planetary gear. One portion of the motive force is used to drive the wheels directly and the other is used to generate electricity using MG1. The electricity from MG1 is used to drive MG2. This supports the directly transmitted engine motive force, contributing to fuel efficiency.

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Drive	*b	Driven - Generates Electricity
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (AC)	-	-

2. If the SOC of the HV battery is low, more engine power is provided to increase the generation of electricity via MG1. This charges the HV battery.

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Drive	*b	Driven - Generates Electricity
   *c	Charged by MG1	-	-
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (DC)		Electrical Power Path (AC)

Driving Condition E: during Full Throttle Acceleration

1. When the vehicle driving condition changes from low load cruising to full throttle acceleration, the system supplements the motive force of MG2 with electrical power from the HV battery.

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Drive	*b	Driven - Generates Electricity
   *c	Discharge	-	-
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (DC)		Electrical Power Path (AC)

Driving Condition F: during Deceleration

1. While the vehicle is being driven with the shift lever in D and it decelerates, the engine turns off and the engine motive force output to the wheels will be zero. At this time, the wheels drive MG2, causing MG2 to operate as a generator and charge the HV battery. While MG2 is operating as a generator, it creates a resistance to rotation at the wheels, producing a braking effect. If the vehicle decelerates at a higher speed, the engine (crankshaft) will not stop turning. The engine will maintain a predetermined speed in order to protect the planetary gear unit. This operation is not shown in the following diagrams:

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Stopped	*b	Rotates Freely
   *c	Driven - Generates Electricity	*d	Charged by MG2
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (DC)		Electrical Power Path (AC)

Driving Condition G: Driving in Reverse

1. While the vehicle is being driven in reverse, its power is delivered by MG2. At this time, MG2 is spinning in the opposite (-) direction of forward travel, the engine can remain stopped, and MG1 is spinning in the (+) direction without generating electricity. While driving in reverse, when any of the conditions monitored by the hybrid vehicle control ECU, such as the SOC of the HV battery, HV battery temperature, engine coolant temperature and electrical load condition, reach a specified level, MG1 will be used to start the engine. The following illustration represents an example when the engine is not running:

   

   Text in Illustration

   *1	Engine	*2	Hybrid Transmission (Hybrid Vehicle Transmission Assembly)
   *3	Power Split Planetary Gear	*4	2-stage Motor Speed Reduction Planetary Gear
   *5	Motor Generator 1 (MG1)	*6	Motor Generator 2 (MG2)
   *7	Inverter with Converter Assembly	*8	Differential
   *9	HV Battery	*10	Transfer
   *a	Stopped	*b	Rotates Freely
   *c	Drive	*d	Discharge
   	Power Transmission		Mechanical Power Path
   	Electrical Power Path (DC)		Electrical Power Path (AC)