Mitsubishi FB13PNT, Quick Start Manual

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CHAPTER 1 CONTROLLER CHAPTER 1 CONTROLLER
9. 9. AC AC M Mot otor or Sy Syst ste em B m Ba asi siccss
9 9..1 1 F Fe ea attu urre e o of f A AC C m mo otto orr
9. 9.2 2 Sp Spee eed co d cont ntro rol of l of in indu duct ctio ion m n mot otor orss
The AC motor model trucks covered by this manual use AC motors (three-phase induction motors) as the traction motor and The AC motor model trucks covered by this manual use AC motors (three-phase induction motors) as the traction motor and
pump motor. AC motors have the following advantages over DC motors: pump motor. AC motors have the following advantages over DC motors:
(1) (1) AC motor AC motors are simple s are simple in construction. in construction. Since they d Since they do not have o not have friction par friction parts like brushes ts like brushes and commu and commutators, daily tators, daily
maintenance is significantly reduced. maintenance is significantly reduced.
(2) (2) AC moto AC motors are com rs are compatib patible with hig le with high-spe h-speed oper ed operatio ation. n.
(3) (3) An AC motor An AC motor of a certain siz of a certain size produces e produces higher power higher power than a DC moto than a DC motor of the same r of the same size. size.
Speed control of DC motors depends on regulation of the Speed control of DC motors depends on regulation of the
field and armature current amounts, while that of AC
field and armature current amounts, while that of AC motors motors
basically depends on adjustment of the frequency of the basically depends on adjustment of the frequency of the
alternating current power supply. The speed of an AC
alternating current power supply. The speed of an AC motor motor
is determined by the frequency of the power supply AC is determined by the frequency of the power supply AC
current and the load on the
current and the load on the motor. motor.
In addition, the voltage and current to the motor must be In addition, the voltage and current to the motor must be
controlled properly so that the motor operates in its
controlled properly so that the motor operates in its
optimum characteristic range. (Fig. 1)
optimum characteristic range. (Fig. 1)
The frequency and voltage can be controlled in a The frequency and voltage can be controlled in a variety of variety of
methods including the "vector control method" employed methods including the "vector control method" employed
in the AC
in the AC motor model trucks. This method provides highly motor model trucks. This method provides highly
responsive control according to ever changing truck- responsive control according to ever changing truck-
operating conditions through a high-speed calculation of
operating conditions through a high-speed calculation of
huge amount of data. The vector control calculation is
huge amount of data. The vector control calculation is
performed by the inverter. (Fig. 2)
performed by the inverter. (Fig. 2)
(Fig. 1) (Fig. 1)
500965 500965
U U
U U V V
V V
V V
W W
V V
W W
IM IM
t t
t t
Inverter Inverter
Low-speed operation Low-speed operation
(low frequency) (low frequency)
High-speed operation High-speed operation
(Fig. 2) (Fig. 2)
500966 500966
IM IM
F F
N N
R R
Accelerator Accelerator
Calculation Calculation
for required for required
output output
Brake Brake
Logic unit Logic unit
Truck Truck
speed speed
Vector control Vector control
calculation calculation
Current Current
Gate Gate
driving driving
pulse pulse
MOS-FET modules MOS-FET modules
Speed Speed
Inverter Inverter
To To rque rque
order order