428 Auto Electricity and Electronics
Figure 22-16. Study the power fl ow through a series-parallel hybrid drive train. A—When operating in all-electric mode, the battery pack energy
is fed to the rear motor-generator. Motor-generator serves as a powerful traction motor to operate the transaxle and drive axles. B—When the
internal combustion engine must be started, battery pack power is sent to both the front motor-generator and rear motor-generator. The front
motor-generator spins the engine crankshaft until the engine “fi res” and runs on its own power. The rear motor-generator keeps propelling the
vehicle until the engine starts to also propel the car. C—When highway cruising, the engine spins the drive train and the front motor-generator.
The front motor-generator powers the rear motor-generator and recharges the battery. D—Under full acceleration, both the front and rear motor-
generators help the engine spin the drive line so the vehicle picks up speed more quickly. E—When decelerating, the engine is shut off and the
drive line rotation spins the rear motor-generator. The motor-generator acts as a generator to quickly recharge the battery pack to ready it for the
next all-electric drive mode. F—In reverse, the power control module spins the rear motor-generator to spin the drive shaft or axles backward.
Power Split Planetary
Gear Unit
Hybrid Transmission
Two-Stage
Motor Speed
Reduction
Planetary
Gear Unit
Electrical Power Path
Mechanical Power Path
HV
Battery
MG1
Inverter
Engine OFF
All-Electric Mode
MG2
A
Power Split Planetary
Gear Unit
Hybrid Transmission
Two-Stage
Motor Speed
Reduction
Planetary
Gear Unit
Electrical Power Path
Mechanical Power Path
HV
Battery
MG1
Engine
Engine Starting
MG2
Inverter
Power Split Planetary
Gear Unit
Hybrid Transmission
Two-Stage
Motor Speed
Reduction
Planetary
Gear Unit
Electrical Power Path
Mechanical Power Path
HV
Battery
MG1
Engine
Highway Cruising
MG2
Power Split Planetary
Gear Unit
Hybrid Transmission
Two-Stage
Motor Speed
Reduction
Planetary
Gear Unit
Electrical Power Path
Mechanical Power Path
HV
Battery
MG1
Engine
Full Acceleration
MG2
Inverter
Power Split Planetary
Gear Unit
Hybrid Transmission
Two-Stage
Motor Speed
Reduction
Planetary
Gear Unit
Electrical Power Path
Mechanical Power Path
HV
Battery
MG1
Engine
Deceleration
MG2
Power Split Planetary
Gear Unit
Hybrid Transmission
Two-Stage
Motor Speed
Reduction
Planetary
Gear Unit
Electrical Power Path
Mechanical Power Path
HV
Battery
MG1
Engine
Reverse
MG2
Inverter
B
C
D
E
F
Inverter
Inverter