SIMULATION OF SPEED CONTROL OF INDUCTION MOTOR USING THREE PHASE
MATRIX CONVERTER
1
CHARU TYAGI,
2ER DURGESH KUMAR
1M.Tech Scholar(Power Electronics & Drives), SWAMI VIVEKANAND SUBHARTI UNIVERSITY
2Asst.Prof. & Head ,Department Of Electrical And Electronics Engineering, SWAMI VIVEKANAND SUBHARTI UNIVERSITY Email: 1[email protected], 2[email protected]
Abstract: This paper presents an overview of the matrix converter technology with its industrial application in induction motor drive and the introduction to direct and indirect matrix converter. Matrix converter is one of the most interesting member of power converter family, provide direct AC-AC conversion. A matrix converter is an ac-ac power frequency converter that received extension research attention due to its single stage power conversion technique, which is an alternate to ac-dc-ac converter.MC (matrix converter ) is capable to convert energy from an ac source to ac load without the need of bulky and life- time limited energy storage elements. And the purpose of most of the modulation methods is to generate sinusoidal current on the input and output sides. This paper also presents the induction motor drive for industrial application, based on matrix converter scheme. The sinusoidal output current, the bidirectional power flow and the lack of limited-lifetime electrolytic capacitors recommend this topology for this application.
Index Terms: AC-AC converter, matrix converter schemes, direct matrix converter, indirect matrix converter, induction motor application
I. Introduction
CONVERTER systems with either a voltage or a current dc- link are mainly used for power conversion from a three-phase mains system to a three-phase load with an arbitrary voltage amplitude and frequency as required, for example for variable- speed drives. Over Recent years, the matrix converter (MC) has attracted the interest of the scientific community due to the advantages it offers [3]–[4].
A matrix converter (MC) delivers the following advantages:
1)
inusoidal input and output current waveforms 2)
ontrollable input power factor (IPF) 3)
perations in all four quadrants of the torque–
speed plane due to the regenerative capability
4)
igh reliability and long life due to the absence of bulky electrolytic capacitors;
5)
maller and lighter design than other regeneration inverters with equivalent power ratings.
Matrix-converter topology can be divided into two type: direct matrix converters (MCs) and indirect matrix converters (2MCs). Direct matrix converters are those which has nine bidirectional switches. The 2MC comprises a four-quadrant current-source rectifier connected to a two-level voltage- source inverter. By applying appropriate modulation scheme [1]–[2] the direct converter and 2MC are able to generate input and output waveforms with the same work of Venturini and Alesina in 1980 [5]. Commutation of the bidirectional switches is the biggest difficulties in the operation of this converter and this can be solved by introducing intelligent and soft commutation techniques. In effect, one big manufacturer of power converters (Yaskawa) is now offering a complete line of standard units for up to several megawatts and medium voltage using cascade connection. These units have rated
power (voltages) of 9–114 kVA (200 and 400 V) for low- voltage MC and 200–6.000 kVA (3.3 and 6.6 kV) for medium voltage.
Here the circuit topology and the operation of matrix converter is present in section IV with its simulation model and results. Introduction to matrix converter is represents in section III , with the introduction of direct and indirect matrix converter.
II.Converters
The conversion of an input ac power at a given frequency to an output power at a different frequency can be obtained using the converters. Restricting the analysis of AC/AC power frequency conversion to static circuits, the available structures can be divided in “direct” and “indirect” power conversion schemes. Indirect schemes consist of two or more stages of conversion and an intermediate DC-link stage is always present. A typical example of two stage indirect AC/DC/AC power frequency conversion is the diode-bridge rectifier- inverter structure, in which an AC power is firstly converted to a DC power (diode rectifier), and then converted back to an AC power at variable frequency (inverter). In direct conversion schemes a single stage carries out the AC/AC power frequency conversion. The scheme shown in Fig.1.1.represents the well-known Diode-Bridge Voltage Source Inverter (DB-VSI) topology that is today the preferred solution in AC drive technology, especially in the low- and medium-power range.
Fig 1.1 Diode rectifier-PWM converter
Example of converters are voltage source inverter, PWM inverter, cycloconverter and matrix converter. VSI and PWM inverter are the example of indirect scheme of conversion i.e
AC-DC-AC conversion , cycloconverter and matrix converter are the example of direct conversion scheme i.e AC-AC conversion.
III Matrix converter
Matrix converters are direct static AC/AC power frequency converters basically consists of an array of static power switches connected directly between the input and output terminals. The matrix converter is nothing but a three-phase to three-phase forced commutated cycloconverter. It consists of nine bidirectional switches that connect each output phase to each input phase, as it is shown in Fig.1.2
va
vc vb
L
L L
Load
3 phase supply Matrix Converter
Filter
Ia
Ib
Ic
Fig 1.2 Three phase to three phase matrix converter The matrix converter topology was originally presented in 1976 by Gyugyi-Pelly [7] but it was in 1980 that the basic configuration and control of three-phase matrix converter were introduced by Venturini in [6]. These papers, along with the progress of the power semiconductor devices technology experienced at that time, boosted a renewed interest in direct AC/AC power frequency converter, as an elegant silicon- intensive and efficient way to convert electric power for motor drives, uninterruptible power-supply and variable frequency generator. Then, many different names have been used in literature to define this converter topology: Unrestricted Frequency Changer and Direct Frequency Changer [7], Generalized Transformer [6], Forced-Commutated Cycloconverter. Matrix Converter, Direct AC/AC Converter [8], Forced-Commutated Direct Frequency Changer , Direct Frequency Changer and Venturini Converter. The matrix
converter replaces the multiple conversion stages and the intermediate energy storage element by a single power conversion stage, and uses a matrix of semiconductor bidirectional switches connecting input and output terminals.
With this general arrangement of switches, the power flow through the converter can reverse. Because of the absence of any energy storage element, the instantaneous power input must be equal to the power output, assuming idealized zero- loss switches. Matrix converters are of two type:- direct matrix converter and indirect matrix converter.
Fig 1.3 a) DMC with bidirectional switch b) indirect matrix converter with virtual DC- link
A) Direct matrix converter
In DMC the output waveforms are made from small pieces of input waveforms. This is possible by selecting the input phases in sequence for defined period of time. The sequence for each phase is same. The output voltages have inside some segments from three input voltages and input current includes segments from three output currents. The direct control of MC is based on mathematical expression [5] given below, which describes conditions between output and input side. And these equations defined the duty cycle for each switch.
Sinusoidal input voltage can be written as
output voltage
input current
Above equations can also be written as:-
Where M(t)= Modulation matrix B) Indirect matrix converter
A principle of indirect matrix converter control strategy is based on virtual DC-link in matrix converter. This DC-link is not physically presented, but the switches are divided to the virtual rectifier and virtual inverter as shown in the Fig.
1.3(b). The indirect space vector modulation is used as a standard technique in the matrix converter modulation. The basic idea of the indirect modulation technique is to decouple the control of the input current and the control of the output voltage.
IV. Working Principle Of MC
MC consists of an array of bidirectional switches, which are used to directly connect the power supply to the load without any intermediate stage.MC is a single stage converter with l×n bidirectional switches that connects an l-phase voltage source to an n-phase load. The MC of 3 × 3 switches, shown in Fig.1.3, is important from a practical point of view because it
connects a three-phase source to a three-phase load, here which is typically a induction motor.
In order to develop a modulation strategy for the MC, it is necessary to develop a mathematical model, which can be derived from fig 1. i.e
And
Where,
ouput voltage
V Simulation and results
The matrix converter is simulated using the Matlab-Simulink package
.
Here by using simulation the speed of induction motor can be controlled. The simulation circuit for induction motor is shown in fig 1.4Fig 1.4 simulation circuit
All simulation results were calculated for source voltage 220 V, 50 Hz.
SIMULATION PARAMETERS
PARAMETERS VALUES
Source voltage amplitude Vin 220V Input frequency, Fi 50 Hz
Load resistance, R 8Ω
Load inductance, L 5mH
Input filter inductance, Ls 0.7mH Input filter resistance, Rs 0.8Ω
The direct control of matrix converter simulation results i.e matrix converter output voltage, speed of the motor and the stator current shown in figures, below.
Fig 1.5 Matrix converter output voltage (line)
Fig 1.6 simulation result for Speed of motor
Fig 1.7 Simulation result for stator current of machine
VI.Conclusion
In this paper, the operating principle of the matrix converter along with the simulation of speed control of induction motor using three phase matrix converter has been discussed. In addition, it can be observed that the matrix converter can generate output frequencies that are not restricted by the source frequency. If drive system is used with MC, then the drive system is capable to operate in all four-quadrant regions.
The simulation results agree with the theoretical expectations, that the direct converters are able to create sinusoidal waveforms on output side as shown in fig 1.5, which is necessary for a good working condition of drive systems. And the parameters of the motor i.e speed of rotor and stator current, shown in fig 1.6 and 1.7 respectively.
Refrences
[1]. Alesina and M. Venturini, “Intrinsic amplitude limits and optimum design of 9-switch direct PWM AC-AC converters,”
in Proc. PESC, 1988, vol. 2, pp. 1284–1291
[2]. D. Casadei, G. Serra, A. Tani, and L. Zarri, “Matrix converter modulation strategies: A new general approach
based on space vector representation of the switch state,”
IEEE Trans. Ind. Electron., vol. 49, no. 2, pp. 370– 381, Apr.
2002.
[3]. P. Wheeler, J. Rodriguez, J. Clare, L. Empringham, and A. Weinstein, “Matrix converters: A technology review,”
IEEE Trans. Ind. Electron., vol. 49, no. 2, pp. 276–288, Apr.
2002.
[4]. D. Casadei, G. Serra, A. Tani, and Z. Luca, “Matrix converter modulation strategies: A new general approach based on space-vector representation of the switch state,”
IEEE Trans. Ind. Electron., vol. 49, no. 2, pp. 370– 381, Apr.
2002
[5] P. Chlebis, P. Simonik, and M. Kabasta “The Comparison of Direct and Indirect Matrix Converters” Cambridge, USA, July 5-8, 2010
[6] M. Venturini, “A new sine wave in, sine wave out, conversion technique eliminates reactive elements,” in Proceedings of Powercon 7, San Diego,CA, 1980, pp. E3-1- E3-15.
[7] L. Gyugyi, B.R. Pelly, “Static Power Frequency Changers.
Theory, performance and applications,” ISBN 0-471-678000- 7, 442 pages, John Wiley & Sons,USA, 1976.
[8] A. Alesina M. Venturini, “Analysis and Design of Optimum-Amplitude Nine-Switch Direct AC-AC Converters”, IEEE Transactions on Power Electronics, Vol. 4, no. 1, pp. 101-112, January1989.
