432 Auto Electricity and Electronics
Power Converter
A power converter in the power control module can
step DC voltage up or down. It does not change AC to DC
or DC to AC. The HV battery pack voltage must usually be
stepped up to more effi ciently drive the inverter circuit and
the motor-generator at high power levels.
As shown in Figure 22-23, the power converter can
step up the battery pack’s 288 volts to 650 volts DC before
the voltage is fed into the inverter circuit. The converter can
also change 650 volts DC back to 288 volts DC for battery
pack recharging.
Figure 22-6 shows a hybrid circuit for stepped-down
high voltage for charging the system’s 12-volt battery. Note
how the circuit uses a transformer, induction coil, transis-
tors, and diodes to change 288 volts DC into 13 to 14 volts
DC for recharging the 12-volt battery.
The low-voltage DC (13 to 14 volts) is sent to the con-
ventional 12-volt battery so it is recharged and ready for the
next starting or idle stop cycle. The 12 volts DC is needed
to operate the conventional 12-volt components when the
motor-generator is not generating electricity.
Motor-Generator ECU
The motor-generator ECU inside the power control mod-
ule controls the inverter and converter circuits to effi ciently
operate the motor-generator(s). The motor-generator ECU
responds to control signals from the hybrid transaxle ECU.
Hybrid Power Control Module Operation
As shown in Figure 22-24, when the driver moves the
gear shift lever, a shift position sensor signals the transaxle ECU
of the selected gear position (park, reverse, neutral, and drive).
This allows the transaxle ECU to operate the power split device
(discussed in the following section) and motor-generator ECU
Figure 22-23. Diagram shows how 288 volts DC enters the power control module from the battery pack. Converter boosts this voltage
to 650 volts DC. Inverter then converts the 650 volts DC into three-phase AC.
Motor-Generator 1
Motor-Generator 2
Motor-Generator 3
Three-
Phase AC
Inverter
650 VAC
Converter
650 VDC
Power Control Module
288 Volts
DC
Hybrid
Battery Pack
Figure 22-24. Study this simplifi ed diagram of how a gear shift lever operates a hybrid electric drive system. Moving the gear shift
lever into drive moves the sensor contacts to signal the transaxle ECU. Transaxle ECU can then control the power control module,
motor-generator ECU, converter, and inverter, which operate the motor-generators to engage the electric drive train. When the throttle
pedal is pressed, three-phase current is sent into one or more motor-generators to accelerate the vehicle using electric propulsion.
Shift Lever
Shift Position
Sensor
Shift Cable
Transaxle
ECU
Motor-
Generator
ECU
Inverter
Converter
Throttle Control Motor
on Engine
M1G1 M1G2 M1GR*
RV
FD
MJ
P
R
N
D
B
Throttle
Pedal
Throttle Sensor
Power Control Module