9.4 ITC vector drive system
As stated above, in the last few decades the improvements in Electronics have made
possible to use complex control system also for AC induction motors, in order to precisely
set the output torque by employing Intelligent Torque Controls (ITC).
The most efficient algorithm is the flux vector control, which is based on a flux and torque
control, depending on motor parameters knowledge and speed and current
measurements. It is more complex than different control algorithms (like scalar control or
slip control), but it gives much more performance, zero speed control, fast and precise
dynamical response and more efficiency.
9.4.1 Basic operation of ITC vector drive system
The motor control algorithm used by SME is known as Field Orientated Control. A
schematic block diagram of a flux vector control is reported in figure 13.
The vector flux control used by SME motor drive systems involves the following blocks:
●
Speed reference block
. The reference speed is set by pedal accelerator, which is
limited and interlocked with other various signals such as: Seat, Hand brake, Pedal
brake, Start, Forward, Reverse, Steering position.
The resulting speed N
r
is compared with the motor actual speed N
m
calculated from
the motor speed sensor signal. A regulator sets a required torque T
r
to correct the
speed error.
●
Speed sensor.
A quadrature pulse encoder is installed in the AC motor as speed
sensor measuring the speed and the direction of the rotation.
●
Flux position.
The flux position is estimated and sent to the PWM modulator and
current decoupling blocks.
●
Current decoupling
. The phase currents are measured and decoupled using
suitable transformations and sent to the flux and torque estimators.
●
Torque control
. The required torque T
r
is compared with the estimated torque T
e
and
the error is sent to a PI regulator.
●
Flux control
. The required flux F
r
is compared with the estimated flux F
e.
●
Inverter voltage
. Combining the U
sx
and U
sy
voltage with flux frequency, a Space
Vector PWM modulator is used to generate the logic state of the signals which drive
the MOSFET's in the power module.
PRELIMINARY VERSION
54
Summary of Contents for AC-M1
Page 1: ...AC M1 AC M1 PRELIMINARY VERSION...
Page 9: ...Figure 1 AC M1 All the dimensions are in millimetres PRELIMINARY VERSION 9...
Page 13: ...Figure 2 Planarity specifications for the AC M1with aluminium baseplate PRELIMINARY VERSION 13...
Page 21: ...Figure 3 General electrical vehicle PRELIMINARY VERSION 21...
Page 32: ...Figure 5 Interconnection cable PRELIMINARY VERSION 32...
Page 36: ...Figure 9 Drawing of COMPACT display slot PRELIMINARY VERSION 36...
