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 rotation sensor 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, MGR* and the engine. Furthermore, the hybrid vehicle control ECU optimally controls the output and torque of MG1, MG2, MGR* 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) of the HV battery 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 and MGR* motive force.

3. The ECM appropriately performs ETCS-i control, fuel injection volume control, ignition timing control and 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, MG2 and MGR* in order to achieve the required MG2 and MGR* motive force.

   
   

   • *: AWD models

     

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 the battery becomes discharged by MG2 or MGR* 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 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.

   
   

   • *: AWD models

     

Inverter Coolant Cooling Control

1. The hybrid vehicle control ECU receives the signal from the temperature sensor for the inverter coolant. Then, the hybrid vehicle control ECU actuates the inverter water pump with motor assembly in 3 levels using duty cycle control, 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 the 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 signal into a digital signal, and transmits the signal to the hybrid vehicle control ECU via serial communication.

   

HV Battery Cooling Control

1. The hybrid vehicle control ECU detects increases in battery temperature via the 7 temperature sensors in the HV battery. Then, the hybrid vehicle control ECU steplessly actuates the battery cooling blower assemblies using duty cycle control, in order to maintain the temperature of the HV battery within the specified range.

2. If there is any leeway in the HV battery temperature while the air conditioning system is operating and cooling down the cabin, 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. If this control was not performed, air taken from the cabin for battery cooling would slow the cooling of the cabin by the air conditioning system.

   

Auxiliary Battery Charging Control

1. The hybrid vehicle control ECU controls the hybrid vehicle converter assembly in accordance with the signals from the auxiliary battery temperature sensor, 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 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 in accordance with requests from the hybrid vehicle control ECU.

   

Motor Generator Main Control

1. MG1, which is driven by the engine, generates high voltage (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 the front wheels.

3. MGR is driven by electrical power from the HV battery and/or MG1, and it generates motive force for the rear wheels.*

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

5. MG1, MG2 and MGR* are shut down when the shift lever is in N. In order to stop providing motive force, it is necessary to stop driving MG1, MG2 and MGR*, because MG1, MG2 and MGR* are mechanically joined to the drive wheels.

6. The Motor Generator ECU (MG ECU), which follows the commands of the hybrid vehicle control ECU, controls MG1, MG2 and MGR* 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 as a generator.

7. 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 generator.

   2. In order to create the motive force required of 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.

   
   

   • *: AWD models

     

     *1	Motor Generator
     *2	On

8. 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 generator, which is driven by the wheels, is utilized to charge the HV battery or drive another motor generator.

      

      *1	Motor Generator

Boost Converter Control

1. The boost converter boosts the HV battery voltage of DC 244.8 V (nominal) 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 of DC 650 V (maximum) to DC 244.8 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	Inverter
   *b	Reactor
   *c	HV Battery
   *d	Boost IPM

5. The boost converter boosts the HV battery voltage from DC 244.8 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 244.8 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 244.8 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.

   

Inverter Control

1. The inverter converts the direct current from the HV battery into alternating current for MG1, MG2 and MGR*, 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 or MGR*. 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 or MGR*. This is necessary because the frequency of the alternating current output by MG1 is not appropriate for control of MG2.

2. The MG ECU transmits signals to the power transistors in the inverter for switching the U, V and W phases of stator coils of MG1, MG2 and MGR* based on the rotor position information sent by the MG1, MG2 and MGR* rotation sensors.

3. When the shift lever is in N, or the hybrid vehicle control ECU has received an overheating, overcurrent, 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, MG2 and MGR*.

   
   

   • *: AWD models

     

Hybrid Vehicle Converter Assembly Control

1. The hybrid vehicle converter assembly reduces the nominal voltage of the HV battery from DC 244.8 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 assembly, the hybrid vehicle control ECU transmits the output voltage request signal to the hybrid vehicle converter assembly in response to the auxiliary battery temperature sensor signals.

   

E-Four System Control (AWD Models)

1. The AWD control section in the hybrid vehicle control ECU calculates the proper drive torque distribution for the front and rear wheels based on the input signals from various sensors, and MG2 and MGR are controlled according to the drive torque distribution calculated by the AWD control section.

2. E-Four system control calculates an optimum front to rear torque distribution ratio based on the signals from various sensors and the hybrid vehicle control ECU.

   

3. E-Four system control is performed as follows in accordance with each driving condition, achieving optimum start-off performance, driving stability and the effective use of energy.

   E-Four System Control

   Driving Condition	Control
   During Normal Driving	The driving condition is set to AWD control when starting off to ensure traction. In order to enhance fuel economy, the motive force distribution to the rear wheels is reduced when a stable driving condition has been determined.
   During Driving on Slippery Surface	The slippage of the front and rear wheels is suppressed and traction performance on slippery roads is ensured. Also, by performing AWD control according to the vehicle driving conditions when turning, cornering stability is enhanced.
   During Driving on Uphill Slope	AWD control according to the uphill slope angle is performed to ensure uphill slope starting off performance.

1. AWD Control during Normal Driving

   
   

   • When starting off, the hybrid vehicle control ECU determines the driving condition from the throttle opening and vehicle speed and optimally distributes the motive force to the front and rear wheels to ensure starting off performance and to prevent the tight corner braking phenomenon* that occurs during cornering.

   • The E-Four system control performs various calculations from the vehicle speed and accelerator opening angle, etc., and continuously variably adjusts the motive force distribution to the front and rear wheels from the front wheel drive condition. As a result, the proper motive force distribution under various driving conditions is achieved for driving stability.

   • When the hybrid vehicle control ECU has been determined that the vehicle driving conditions and driver operation conditions are stable based on the throttle opening angle and vehicle speed signals, the motive force distribution to the rear wheels is decreased and close condition to the front wheel drive is achieved for fuel efficiency.

   • During deceleration, AWD control is canceled and the effectiveness of ABS control and VSC control is increased.

     Tech Tips

     *: The tight corner braking phenomenon is the phenomenon in which it seems as if the brakes are applied when a rotational difference between the front and rear wheels is necessary such as during cornering, and this rotational difference cannot be absorbed during all-wheel driving on AWD models with the front and rear wheels directly connected.

2. AWD Control during Cornering on Slippery Surface

   
   

   • The actual yaw rate detected from the sensors installed on the vehicle and the target yaw rate calculated using the steering angle signals and, vehicle's longitudinal and lateral acceleration speed signals according to the driver's operation are compared in order to determine the vehicle behavior.

   • Performing optimal front and rear wheel motive force distribution according to the driving conditions allows cornering stability in which the vehicle path the driver intended is achieved.

     

     *a	Understeer Tendency	*b	Target Line
     *c	Oversteer Tendency	*d	Motive Force Distribution to Rear Wheels Increased
     *e	Motive Force Distribution to Rear Wheels Reduced	-	-

Battery Voltage Sensor Control

1. The battery voltage sensor converts the HV battery related signals (voltage, current and temperature) into digital signals, and transmits them to the hybrid vehicle control ECU via serial communication. These signals are needed to determine the charge or discharge values that are calculated by the hybrid vehicle control ECU.

2. A leakage detection circuit is provided in the battery voltage sensor in order to detect any electrical leakage from the HV battery or high voltage circuit. Also, the battery voltage sensor detects the feedback frequency from the battery cooling blower assemblies, which is needed by the hybrid vehicle control ECU to perform HV battery cooling control. The battery voltage sensor converts the electrical leakage and feedback frequency information into digital signals and transmits them to the hybrid vehicle control ECU via serial communication.

   

Skid Control ECU 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 assembly 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), 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, MG2 and MGR* in accordance with the present driving conditions in order to suppress the motive force.

   
   

   • *: AWD models

     

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 airbag ECU assembly during a frontal collision, side collision, side rear collision or rollover*. In the event of a rear collision, the airbag ECU assembly also sends a signal.

   
   

   • *: Models for Korea

   

Drive Start Control System

• When abnormal driver accelerator pedal and shift operations are detected, the system limits the motive force and informs the driver.

  

  CAUTION:

  When the system is operating, even if the driver depresses and holds the accelerator pedal, motive force may increase on an uphill slope and decrease on a downhill slope. This behavior allows the system to restrict the vehicle speed and acceleration below the predetermined limit on slopes and is not a malfunction.

1. Control during Reverse Operation

   
   

   • Responds to excessive depression of the accelerator pedal while operating in reverse.

   • Corrects motive force according to the road grade and steering angle.

     Control Start Conditions (When all of the following conditions are met, control starts.)	Shift position is R. Accelerator pedal is depressed.
     Control Operation	Limits the motive force so the vehicle speed and acceleration are at or below a certain level.
     Control Stop Conditions	Shift position is not R. Accelerator pedal is fully released.

     

2. Control during Manual Shift Operation

   
   

   • Responds to shift operations with the accelerator pedal depressed.

   • Changes the limit amount according to the manual shift operation pattern.

   • Corrects motive force according to the road grade and steering angle.

     Control when Starting Off from a Parked Position

     Control Start Conditions (When all of the following conditions are met, control starts.)	Shift position is changed from P to D, or P to R. Accelerator opening angle is approximately 1/5 or higher.
     Control Operation	Limits the motive force so the vehicle speed and acceleration are at or below a certain level.
     Control Stop Conditions	Shift position is P or N. Accelerator pedal is fully released.

     Figure 1. Image of Control when Starting Off from a Parked Position

     

     Control during Other Situations

     Control Start Conditions (When all of the following conditions are met, control starts.)	Shift position is changed from R to D, D to R, or N to R. Accelerator opening angle is approximately 1/5 or higher.
     Control Operation	Limits the motive force so the vehicle speed and acceleration are at or below a certain level.
     Control Stop Conditions	Shift position is P or N. Accelerator pedal is fully released.

     Figure 2. Image of Control during Other Situations

     

     CAUTION:

     
     

     • The motive force restraint level differs in the above 2 situations.

     • During control while a manual shift operation is performed (from control start until the accelerator pedal is released), the system informs the driver of the control via the multi-information display.

Drive Mode Select

1. The motive force characteristics for the accelerator opening angle can be changed through the selection of the drive mode according to driver preference.

2. The drive mode can be switched by turning the dial type drive mode select. In addition, the vehicle can be returned to NORMAL mode by pressing the drive mode select.

3. An indicator is provided in the combination meter assembly and the drive mode the driver selected can be recognized. Also, the hybrid system indicator switches to the tachometer display when SPORT mode*1 or SPORT S/S+ mode*2 is selected.

   
   

   • *1: Models without AVS

   • *2: Models with AVS

   

   *A	Models without AVS	*B	Models with AVS
   *1	Integration Control and Panel Assembly	*2	Drive Mode Select

4. The characteristics of each drive mode are as follows:

   Characteristics of Drive Mode

   Drive Mode	Characteristics
   NORMAL Mode	This drive mode provides optimum driveability.
   ECO Mode	The hybrid vehicle control ECU optimizes fuel economy and driving performance by gradually generating the motive force in comparison to the accelerator pedal operation. At the same time, the ECU supports eco driving by optimizing air conditioning performance.
   SPORT Mode*1 SPORT S/S+ Mode*2	The hybrid vehicle control ECU controls motive force in the intermediate area of the accelerator pedal opening to a greater degree than that of NORMAL mode, improving acceleration performance. In addition, engine speed response performance has been improved in the high area of the accelerator pedal opening, thus producing a sporty drive.

   
   

   • *1: Models without AVS

   • *2: Models with AVS

     Figure 3. Motive Force Output Characteristics