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Simulation of DTC Strategy in
VHDL Code for
Induction Motor Control
Marcelo F. Castoldi, Manoel L. Aguiar
IEEE ISIE 2006, July 9-12, 2006, Montreal, Quebec, Canada
ptt製作:100%
指導教授： 龔應時
學
生： 顏志男
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OUTLINE
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ABSTRACT
INTRODUCTION
DTC STRATEGY
VHDL AND FLOATING POINT
SIMULATION
RESULTS
CONCLUSIONS
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ABSTRACT
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This paper presents a simulation of Direct Torque Control (DTC) strategy, used to control
induction motors.
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This simulation was realized with Matlab and Modelsim programs.
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The Matlab/Simulink was used to simulate the motor dynamics and the inverter of the control
system.
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The DTC strategy was executed in Modelsim using VHDL floating point.
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INTRODUCTION
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The present paper shows the simulation ofthe DTC induction motor drive using Matlab and
the Modelsim programs operating simultaneously.
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The power-drive and the induction motor model have been implemented in the
Matlab/Simulink program.
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The calculations of DTC strategy was implemented in VHDL code using Modelsim program.
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The Link-for-ModelSim toolbox executes the cosimulation using a VHDL code font running
in ModelSim program.
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DTC STRATEGY(1/3)
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The DTC technique is a control principle of optimized AC drive, where the inverter's
switching controls directly the flux and torque motor variables [7].
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The inverter's switches impose the required voltages on the motor, which will control both
torque and flux in a closed-loop control.
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The DTC technique is represented by Fig. 1.
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DTC STRATEGY(2/3)
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DTC STRATEGY(3/3)
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The motor model calculates the stator flux and torque magnitudes and the flux spatial sector in
the stationary stator reference frame.
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VHDL AND FLOATING POINT
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VHDL is a code for VHSIC (Very High Speed Integrated Circuit) hardware description
standardized for IEEE 1076.1, which offers many advantages for digital projects [9].
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Although integer numbers supply accurate representation of numerical values, they have a
great disadvantage:
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the inability to represent fractionary values. Arithmetic in floating-point resolves this
problem.
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It causes a loss of speed, however, the benefits with its use surpasses this disadvantage.
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The ANSI/IEEE 754 standard was created to facilitate the portability of programs, which use
floating-point, between different computers.
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SIMULATION(1/2)
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In this project, the DTC strategy was simulated, using general Simulink blocks, Power
System-Blockset modules and a block for co-simulation in VHDL.
The system used can be seen in Fig. 3.
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The flux motor model, as well the hysteresis comparators of flux and torque and the flux
spatial sector are the first part ofthe VHDL code.
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This methodology was applied to simulate the routine that can be later implemented in
FPGA's.
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SIMULATION(2/2)
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RESULTS(1/7)
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The results were analyzed comparing the VHDL simulation results to the Matlab results.
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The latter results were obtained through the Machines Measurement Demux toolbox
(SimPowerSystems).
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The system simulation of Fig. 3 was started setting a value for torque and flux references. The
motor data are:
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RESULTS(2/7)
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RESULTS(3/7)
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RESULTS(4/7)
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RESULTS(5/7)
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RESULTS(6/7)
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RESULTS(7/7)
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CONCLUSIONS
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The simulation proposal using Matlab and Modelsim programs in cosimulation mode has
presented satisfactory results as demonstrated in this work.
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The VIHDL code using floating-point presented good results and very accurate calculations
of the motor parameters, providing the good functioning of the DTC.
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Another significant advantage of the co-simulation aspect is the great risk reduction of
significant changes in the code for one future implementation in the hardware.
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