Nissan Altima HL32 Hybrid. Manual - part 566

HYBRID CONTROL SYSTEM

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FUNCTION DIAGNOSIS

HYBRID CONTROL SYSTEM

System Diagram

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System Description

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DESCRIPTION

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HYBRID CONTROL SYSTEM

General

The Hybrid Vehicle Control system optimally effects cooperative control of a QR25DE engine and a high-

speed, high-output MG2 through a hybrid transaxle that provides excellent transmission performance.

Furthermore, it uses a variable-voltage system consisting of a high-output HV battery with a nominal voltage of

DC 244.8 V, and a boost converter that boosts the operating voltage of the system to a maximum voltage of

DC 650 V.

NOTE:

• Inverter water pump is also called water pump with motor and bracket assembly in this service manual.

• Generator is also called MG1 or motor generator No.1 in this service manual.

• Traction motor is also called MG2 or motor generator No.2 in this service manual.

• Inverter assembly is also called inverter with converter assembly in this service manual.

• Hybrid vehicle converter (DC/DC converter) is also just called DC/DC converter in this service manual.

Driving Performance

This system uses a variable-voltage system that consists of a boost converter to boost the operating voltage to

a maximum voltage of DC 650 V. It is able to drive the MG1 (Motor Generator No.1) and MG2 (Motor Genera-

tor No.2) at a high voltage, and minimizes the electrical loss associated with the supply of electric power at a

smaller current. Thus, it is able to operate the MG1 and MG2 at high speeds and high outputs.

A high driving force is achieved through the synergy effect of the high-speed, high-output MG2 and the high-

efficiency QR25DE engine.

Fuel Economy Performance

• By optimizing the internal construction of MG2, this system realizes a high level of regenerative capability,

thus realizing a high level of fuel economy performance.

• This system stops the engine while the vehicle is idling, and stops the engine as much as possible under

conditions in which the operating efficiency of the engine is poor, allowing the vehicle to operate using only

MG2. Under the conditions in which the operating efficiency of the engine is favorable, the engine operates

to drive the vehicle using MG1 while generating electricity. Thus, this system effects the input-output control

of driving energy in a highly efficient manner to realize a high level of fuel economy.

FEATURES

General

• The Hybrid Vehicle Control System offers the following representative features:

- Uses a variable-voltage system in which a boost converter boosts the operating voltage of the system to a

maximum voltage of DC 650 V and an inverter converts the direct current into an alternating current, which

supplies the system voltage to MG1 and MG2.

- A motor speed reduction planetary gear unit, whose purpose is to reduce motor speed, is used to enable the

high-speed, high-output MG2 to adapt optimally to the power split planetary gear unit in the hybrid transaxle.

• The Hybrid Vehicle Control System consists primarily of the following components:

Variable-Voltage System

In the Hybrid Vehicle Control System, a boost converter is used inside the inverter assembly. The boost con-

verter boosts the system operating voltage to a maximum voltage of DC 650 V and the inverter converts direct

current into alternating current, in order to drive MG1 and MG2 at a high voltage as well as minimize the elec-

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HYBRID CONTROL SYSTEM

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trical loss associated with the electric power supply at a smaller current. Thus, MG1 and MG2 can be operated

at high speeds and high output.

Clutch-Less System

A clutch-less system is used to mechanically link the front wheels and MG2 via gears. To disengage the

motive force in the neutral position, the shift position sensor outputs an N position signal to turn OFF all the

power transistors in the inverter (which controls MG1 and MG2). As a result, the operation of MG1 and MG2

shuts down, thus rendering the motive force at the wheels to zero.

Hybrid Transaxle

• This system drives the vehicle by combining the motive forces of the engine and the MG2 in an optimal man-

ner in accordance with the driving conditions of the vehicle. In this system, the engine power forms the

basis. The power split planetary gear unit in the hybrid transaxle splits the engine power two ways: one to

drive the wheels, and the other to drive MG1, so that it can function as a generator.

• This hybrid transaxle consists primarily of MG1, MG2, a compound gear unit (which consists of a motor

speed reduction planetary gear unit and a power split planetary gear unit), a counter gear unit and a differen-

tial gear unit.

• The engine, MG1 and MG2 are mechanically joined via the compound gear unit.

• The compound gear unit contains a motor speed reduction planetary gear unit and a power split planetary

gear unit. The motor speed reduction planetary gear unit reduces the rotational speed of MG2, and the

power split planetary gear unit splits the motive force of the engine two ways: one to drive the wheels, and

the other to drive MG1, so that it can function as a generator.

• In the motor speed reduction planetary gear unit, the sun gear is coupled to the output shaft of MG2, and the

carrier is fixed. Furthermore, the compound gear unit uses a compound gear, in which two planetary ring

gears, a counter drive gear and a parking gear are integrated.

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HYBRID CONTROL SYSTEM

Link-Less

The Electric Throttle Control Actuator is used. This is a link-less system that does not use an accelerator

cable. Instead, it uses an accelerator pedal position sensor and a throttle position sensor to detect the acceler-

ator pedal position and the throttle position.

The hybrid vehicle ECU calculates the target engine speed and the required engine motive force in accor-

dance with the signals provided by the accelerator pedal position sensor, vehicle driving conditions, and the

SOC (state of charge) of the hybrid vehicle battery. The hybrid vehicle ECU sends the results of this calcula-

tion to the ECM via the CAN communication line. The ECM optimally controls the electric throttle control actu-

ator and sends the actual engine speed signal to the hybrid vehicle ECU. 

Regenerative Brake

The regenerative brake function operates MG2 as a generator while the vehicle is decelerating or braking and

stores this electrical energy in the HV battery.

Basic Operation

This system generates a motive force in combination with the engine, MG1 and MG2 in accordance with the

driving conditions. Representative examples of the various combinations are described below.

Starting (Drive by MG2)

Supply of electrical power from the HV battery to MG2 provides force to drive the front wheels.

During Acceleration with Engine

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