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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
1
OUTLINE
ABSTRACT
INTRODUCTION
DTC STRATEGY
VHDL AND FLOATING POINT
SIMULATION
RESULTS
CONCLUSIONS
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ABSTRACT
This paper presents a simulation of Direct Torque Control (DTC) strategy, used to control
induction motors.
This simulation was realized with Matlab and Modelsim programs.
The Matlab/Simulink was used to simulate the motor dynamics and the inverter of the control
system.
The DTC strategy was executed in Modelsim using VHDL floating point.
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INTRODUCTION
The present paper shows the simulation ofthe DTC induction motor drive using Matlab and
the Modelsim programs operating simultaneously.
The power-drive and the induction motor model have been implemented in the
Matlab/Simulink program.
The calculations of DTC strategy was implemented in VHDL code using Modelsim program.
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)
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].
The inverter's switches impose the required voltages on the motor, which will control both
torque and flux in a closed-loop control.
The DTC technique is represented by Fig. 1.
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DTC STRATEGY(2/3)
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DTC STRATEGY(3/3)
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
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].
Although integer numbers supply accurate representation of numerical values, they have a
great disadvantage:
the inability to represent fractionary values. Arithmetic in floating-point resolves this
problem.
It causes a loss of speed, however, the benefits with its use surpasses this disadvantage.
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)
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.
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.
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)
The results were analyzed comparing the VHDL simulation results to the Matlab results.
The latter results were obtained through the Machines Measurement Demux toolbox
(SimPowerSystems).
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
The simulation proposal using Matlab and Modelsim programs in cosimulation mode has
presented satisfactory results as demonstrated in this work.
The VIHDL code using floating-point presented good results and very accurate calculations
of the motor parameters, providing the good functioning of the DTC.
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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