DIRECT TORQUE CONTROL FOR MATRIX CONVERTER-FED THREE PHASE INDUCTION MOTOR WITH HYBRID PSO
ABSTRACT
Direct Torque Control (DTC) for Induction Motors using Matrix Converters is a high performance motor
control scheme with fast torque and flux responses. This paper presents a new control scheme based on
hybrid particle swarm optimization (HPSO). The main advantages of the matrix converter are combines
with those of the DTC technique, generating the required voltage vectors under 0.9 input power factor
operations. The results demonstrate the good quality and robustness in the system dynamic response and
reduction in the steady-state and transient motor ripple torque.
Keywords: Hybrid Particle Swarm Optimization (HPSO), DTC-Matrix Converter, Induction Motor
1. INTRODUCTION
Matrix converters as induction motor drivers
have received considerable attention in recent years
because of its good alternative to voltage-source
inverter pulse width modulation (VSI-PWM)
converters. In reality, the matrix converter provides
important benefits such as bidirectional power flow,
sinusoidal input current with adjustable
displacement angle (i.e. controllable input power
factor), and a great potential for size reduction due
to the lack of dc-link capacitors for energy storage
[1-4].
Direct torque control (DTC) method has becomes
one of the high performance control strategies for
induction motor to provide a very fast torque and
flux control [5]. It is the direct control of torque and
flux of an electrical motor by the selection through
a look-up table, of the power converter voltage
space vectors. The main advantage of DTC is its
structure simplicity, since no coordinate
transformations, current controllers and PWM are
needed. Moreover the controller does not depend on
motor parameters. DTC is considered to be a simple
and robust control scheme which achieves quick
and precise torque control response. For such
advanced reasons, the combination of the
advantages of the matrix converter with those of the
DTC method is effectively possible [6]. However,
some research is still being done to reduce the
electromagnetic torque ripple, which is its main
drawback that leads to the raising stator current
distortion noise [1]. The following methods are
applied to improve the effects of the ripple on the
torque output: fuzzy logic controller, multilevel
inverter, the modulation methods of the SVM [7-9]
and so on. Using the above methods always
increases the complication of the system structure
and burdens the workload of the DSP because of
complicated calculations such as square root and
trigonometric functions algorithm are involved. It is
crucial to keep the short sampling period time in
order to maintain the electromagnetic torque ripple
within an acceptable hysteresis band [10]. It is
difficult to implement DTC using common IC
hardware. The DTC algorithm is usually
implemented by serial calculations on a DSP board.
However, as a predictive control scheme, the DTC
has a steady-state control error produced by the
time delay of the lengthy computations, which
depends largely on the control algorithm and
hardware performance. A typical DSP (TMS32010)
execution time of the DTC algorithm for a VSI-fed
induction motor is more than 250μs [11]. ANN has
faster parallel calculation and more simple circuit
structure, so it is superior to a DSP board in
execution time and hardware structure. The
execution time of neural devices is less than 0.5μs
(analogue) or 0.8μs (digital) per neuron [12]. So,
DTC of VSI fed induction motor

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