Chapter 22 Hybrid Drive Systems 419
❑
Hybrid power control module—high-voltage elec-
tronic circuit that can change DC into AC, AC into
DC, and amplify or reduce voltage.
❑
Hybrid drive ECU—electronic control unit that moni-
tors driving conditions to help control the operation
of the power control module, battery pack, and
motor-generator.
❑
Hybrid power cables—large orange insulated conductors
that electrically connect the battery pack, power control
module, and motor-generator assemblies together.
❑
Internal combustion engine—gasoline or diesel inter-
nal combustion engine that propels the vehicle at
highway cruising speeds and spins the motor-generator
armature to recharge the HV battery pack.
A conventional fuel tank, fuel lines, and electronic fuel
injection system feed gasoline or another fuel to the inter-
nal combustion engine. The internal combustion engine is
capable of propelling the vehicle and providing energy to
spin the motor-generator armature to recharge the battery
pack using the motor-generator. The motor-generator can
also be used to fully propel the vehicle and help brake or
slow the vehicle when stopping in traffi c. Both of these
systems work together to provide a dependable and fuel-
effi cient means of transportation.
Types of Hybrids
There are several types and classifi cations of hybrid
drive systems. For example, hybrids can be classifi ed by
their drive train confi guration and when they employ their
internal combustion system. You should understand their
differences and similarities.
Series Hybrid
A series hybrid has a separate generator and traction
motor. It does not use a motor-generator. The traction motor
is the only method used to apply torque to the vehicle’s
drive train. The engine has no mechanical connection to
the drive train. At least one major auto manufacturer is
developing a series hybrid for mass production. This is
illustrated in Figure 22-3A.
The series hybrid can operate on all-electric mode
when the battery pack charge is suffi cient to propel the
vehicle from a standstill and in reverse. The gas engine can
remain off. When the battery pack becomes drained, the
internal combustion engine starts and turns on the genera-
tor to charge the battery pack.
Parallel Hybrid
A parallel hybrid uses both the internal combustion
engine and motor-generator to apply mechanical torque to
the drive train. The engine and motor-generator work in
parallel, or at the same time. See Figure 22-3B.
Figure 22-3. Compare the three most common types of hybrid drive
confi gurations. A—Series hybrid. B—Parallel hybrid. C—Series-
parallel hybrid. (Toyota)
Generator
A
B
C
Battery
Pack
Power
Control
Module
Motor
Drive
Out
Internal
Combustion
Engine
Transmission
Battery
Pack
Power
Control
Module
Motor-
Generator
Drive
Out
Engine
Power
Control
Module
Drive
Out
Engine
Generator
Battery
Pack
Motor
Power
Splitter