Features (Selling Points); Major Selling Points; Adoption Of Ac Motor Drive System; What Is Ac Motor Drive System? - Toyota 7FBEF 15 Service Manual

FEATURES (SELLING POINTS)

I Major selling points
The greatest feature of the new models is adoption of the AC motor drive system. New features of the 7FB
series have also been adopted in many places.

1. Adoption of AC Motor Drive System

What is AC motor drive system?

The conventional DC motor drive system uses a controller for battery current chopping (ON and OFF)
to control the motor power by changing the chopping ratio to realize from inching at the time of starting
up to the maximum power.
The controller in the AC motor drive system converts the battery current to a three-phase alternate
current, whose sine wave form (frequency and waveform height) varies to control the motor power.
The table below compares the motor voltage, motor structure and the controller between the AC
system and DC system.
Comparison between the DC and AC systems
Motor voltage
Con-
troller
DC
sys-
tem
Battery voltage
• Conversion from battery DC
voltage into the mean volt-
age by the chopper
Con-
troller
Battery voltage
AC
sys-
tem
• Conversion from battery DC
voltage into the AC voltage
by the controller
Mean voltage
Commutator
ON ON ON
Motor voltage
• Need of brush and commu-
tator maintenance
• Complicated structure
Sine wave
Stator core
Motor voltage
• No brush and commutator
(maintenance-free)
• Compact and lightweight
Motor structure
Brush
Stator coil
Controller
M
Battery
Microcomputer
control
Contactor
• Relatively easy by mean DC
voltage control
• Need of contactor for rotat-
ing direction change
Battery
1 Phase
Microcomputer
control
• Conversion from DC into
three-phase AC by the mod-
ule
• No need of contactor for
rotating direction change
1-3
2
3
1
Motor
Motor
M