HYBRID CONTROL SYSTEM

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. This hybrid vehicle uses LEXUS Hybrid Drive to drive the front wheels to ensure high fuel economy performance and drive performance by cooperating the engine and motor generators efficiently.
3. Furthermore, AWD models use an E-Four system that is combined with LEXUS Hybrid Drive and has a high output and high efficiency motor to drive the rear wheels. A front wheel drive condition that emphasizes fuel economy is variably adjusted to an all-wheel drive condition that emphasizes traction performance, and a proper drive torque distribution for various driving conditions is possible for both high fuel economy performance and traction performance.
4. This hybrid vehicle uses a combination of 2 kinds of power sources, such as an engine and electric motor, 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.
5. 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.
6. 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.
7. Hybrid vehicles have high-voltage electrical circuits. Hybrid vehicles have been developed with consideration given to the protection of drivers and technicians against electrocution.

SPECIFICATION

Hybrid System
Maximum System Output*1	147 kW 145 KW*2

Tech Tips

*1: Maximum system output is the combined power of the engine and the electric motor.

*2: Models for Korea

Inverter with Converter Assembly
Boost Converter	Rated Voltage (Inverter Side)	DC 650 V
Boost Converter	Rated Voltage (HV Battery Side)	DC 244.8 V
Hybrid Vehicle Converter Assembly	Rated Output Voltage	DC 11 V to 15 V
Hybrid Vehicle Converter Assembly	Maximum Output Current	120 A

Cooling System
Inverter Water Pump with Motor Assembly	Motor Type		Brushless
	Discharge Volume	High	12 L/min (12.7 US qts, 10.6 Imp. qts) or Greater at 65°C (149°F)
		Mid	9 L/min (9.5 US qts, 7.9 Imp. qts) or Greater at 65°C (149°F)
		Low	7 L/min (7.4 US qts, 6.2 Imp. qts) or Greater at 65°C (149°F)
Inverter Coolant	Type		Toyota Genuine Super Long Life Coolant (SLLC) or Equivalent
	Color		Pink
	Capacity		3.1 Liters (3.3 US qts, 2.8 Imp. qts)
	Maintenance Intervals	First Time	240000 km (150000 miles) or 7 years
		Subsequent	Every 80000 km (50000 miles) or 4 years

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

MAIN FEATURES

Hybrid vehicles have 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.

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.

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.

Series-type Hybrid System

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

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

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.

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

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).

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

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

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.

*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)	-	-

The LEXUS Hybrid Drive optimally performs cooperative control of the high-output 2AR-FXE 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.
Hybrid vehicles have 2 batteries that are used for different purposes. One is the HV battery (nominal voltage of DC 244.8 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.
Furthermore, it uses a variable-voltage system consisting of a high-output HV battery with a nominal voltage of DC 244.8 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
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.

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.

*A	2WD Models	*B	AWD Models
*1	2AR-FXE Engine	*2	Inverter with Converter Assembly Boost Converter Inverter Hybrid Vehicle Converter Assembly
*3	P314 Hybrid Transaxle (Hybrid Vehicle Transaxle Assembly) Motor Generator No. 1 (MG1) Motor Generator No. 2 (MG2)	*4	HV Battery Assembly (DC 244.8 V)
*5	Auxiliary Battery (DC 12 V)	*6	Q211 Rear Drive Unit (Rear Traction Motor with Transaxle Assembly) Motor Generator Rear (MGR)

PRECAUTION

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.

Insulation of High-voltage Circuits

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

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.

*A	2WD Models	*B	AWD Models
*1	Compressor with Motor Assembly	*2	Inverter with Converter Assembly
*3	P314 Hybrid Transaxle (Hybrid Vehicle Transaxle Assembly) Motor Generator No. 1 (MG1) Motor Generator No. 2 (MG2)	*4	Power Cable
*5	Service Plug Grip	*6	HV Battery Assembly
*7	Q211 Rear Drive Unit (Rear Traction Motor with Transaxle Assembly) Motor Generator Rear (MGR)	-	-

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.
  - Power switch is turned off.
  - Any airbag is deployed.
  - Inverter UPR cover is removed (interlock circuit is opened).
  - Connector cover assembly is removed (interlock circuit is opened).
  - Connector of the inverter hybrid connector assembly is disconnected (interlock circuit is opened).
  - Service plug grip handle is raised partway (interlock circuit is opened)*.
  - 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.
  
  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.