Simulation of a Single-Phase Cycloconverter Based Matrix Converter Topology using MATLAB/Simulink

Simulation of a Single-Phase Cycloconverter Based Matrix Converter Topology using MATLAB/Simulink

S. Sudha Rani

Assistant Professor EEE, MGIT Hyderabad, India

Dr. M. Nalini Devi

Assistant Professor EEE, MGIT, Hyderabad, India

E. Deepika

Student EEE, MGIT Hyderabad, India

Abstract – The field of power electronics mainly deals with the conversion of power from one form to another and the change of voltage level to another by using different power electronic converters. There are many control strategies used in the aid this conversion. The main types of conversion are cycloconverter, rectifier, inverter and chopper.

A single-phase matrix converter (SPMC) is a power conversion topology that employs a bilateral switch matrix (typically four bidirectional IGBT switches arranged in a 2×2 configuration) to connect a input source directly to a output load without requiring any intermediate DC-link capacitor or energy storage elements.The converter can synthesize a controllable output voltage with variable amplitude and frequency (both higher and lower than the input) while achieving near-unity input power factor and bidirectional power flow capability.

The single-phase cycloconverter is a well-established direct AC-AC frequency changer widely used for low-frequency applications such as speed control of single-phase induction motors and induction heating. Traditionally, it is realized using thyristor-based phase-controlled circuits, which suffer from poor input power factor, high harmonic distortion, and limited output frequency (typically less than or equal to input frequency/3).

The present work implements a single-phase cycloconverter using matrix converter topology in SIMULINK, by leveraging the inherent advantages of matrix converter technology.

Index TermsCycloconverter, Matrix Converter, AC-AC Con-version, Simulink, Power Electronics

1. Introduction

   Power electronics fundamentally revolves around efficient, controlled, and reliable energy conversion between different forms to meet the diverse requirements of modern electri-cal systems. The four primary conversion categories AC-DC (rectification), DC-AC (inversion), DC-DC (chopping), and direct AC-AC (frequency/amplitude alteration) address nearly all industrial and domestic needs.

   Among these, direct AC-AC conversion without an interme-diate DC link has always been desirable because it potentially offers higher efficiency, reduced size, lower cost, and longer lifetime by eliminating bulky electrolytic capacitors. While controlled rectifiers and inverters connected through a DC link

   dominate most applications, direct AC-AC topologies become particularly attractive in scenarios demanding compact design, high reliability, four-quadrant operation, and sinusoidal input current with unity power factor.

   Traditional single-phase AC-AC conversion for variable-frequency applications has been largely synonymous with the thyristor-based cycloconverter, a naturally commutated direct frequency changer capable of producing output frequencies lower than the input (typically limited to fin/3).

   Despite its simplicity and robustness, the conventional cy-cloconverter suffers from well-documented drawbacks:

   • poor input power factor that deteriorates severely at low output frequencies

   • high harmonic distortion in both input current and output voltage

   • subharmonic generation

   • limited maximum output frequency (fo fs/3)

   These shortcomings make it increasingly incompatible with modern grid codes, electromagnetic compatibility standards, and energy-efficiency regulations, thereby motivating the search for alternative topologies that retain the advantages of direct conversion while overcoming the limitations of phase-controlled thyristor circuits. This is the reason for the tremendous interest in matrix converter topology as the ideal features can be fulfilled.

   A. Problem Statement and Project Objectives

   Problem Statement: Conventional single-phase thyristor cycloconverters suffer from: output frequency limited to one-third of input frequency ,High low-order harmonics, poor input power factor that deteriorates severely at low output frequencies. These limitations restrict their use in modern high-performance drives. Single Phase Matrix Converter is proposed as a potential solution to meet all the requirements of the ideal frequency changer.

   Primary Objectives:The objective of this work is to design and validate in MATLAB/Simulink a high-performance single-phase cycloconverter using 2×2 matrix converter topology

   that overcomes the limitations of conventional thyristor-based designs by:

   1. Implementing safe four-step commutation with IGBT-based bidirectional switches

   2. Achieving sinusoidal output voltage at any frequency

   The AC-AC converter is used to convert an alternating volt-age at supply frequency is converted directly to an alternating voltage at load frequency. The proposed converter topology is more efcient when compared to the conventional converters to overcome the drawbacks and achieve the true single stage cycloconversion with superior waveform quality.

2. Literature Review

   The modern industrial landscape and motion control sys-tems heavily rely on power electronic converters to achieve efcient and exible energy conversion. Traditional AC-AC converters often utilize an intermediate DC link, which neces-sitates bulky and short-life reactive energy storage components (capacitors and inductors). This drawback led researchers to investigate direct AC-AC power conversion topologies, most notably the matrix converter (MC).

   • Maxym Vorobyov, Overview of Single Phase Matrix Converter Applications

   • Zuckerberger, A., Weinstock, D., Alexandrovitz A., Single-phase Matrix Converter, IEE Proc.Electric Power App, Vol.144(4), Jul 1997 pp 235-240.

   • Modelling Simulation of Single-phase Matrix Con-verter as a Frequency Changer with Sinusoidal Pulse Width Modulation Using MATLAB/Simulink ,Confer-ence: Power and Energy Conference, 2006. PECon 06. IEEE International.

   • B. R. Pelly, Thyristor Phase-Controlled Converters and Cycloconverters, Wiley, New York, 1971

   • Zahirruddin Idris, siti Zaliha mahammud noor, Musta-far kamal HamzaSafe Commutation Strategy in Single Phase Matrix Converter IEEE PEDS 2005 Conference.

   The single-phase matrix converter (SPMC)-based cyclo-converters, pioneered by Zuckerberger (1997) and advanced by Idris and Hamzah (20052006), successfully overcome the classic thyristor cycloconverter limitations documented by Pelly (1971)poor power factor, high THD, subharmonics, and fout n/3while eliminating DC-link capacitors and achieving unity power factor and low distortion through si-nusoidal PWM and safe four-step commutation.

   Despite mature theory and numerous Simulink validations, comprehensive, fully integrated, and openly accessible models remain scarce. This work lls that gap by delivering a com-plete, high-performance, validated Simulink implementation of the SPMC cycloconverter for both resistive and inductive loads across a wide frequency range.

3. Proposed Methodology

   1. Matrix Converter Topology

      The MatrixConverter is a single-stage converter which has an array of m × n bidirectional power switches to connect, directly, an m-phase voltage source to an n-phase load. It is also dened as is a forced commutated converter which uses an array of controlled bidirectional switches as the main power elements to create a variable output voltage system with unrestricted frequency. As shown in the gure 1, the Single-Phase Matrix Converter (SPMC) consists of a matrix of input and output lines with four bidirectional switches connecting the single-phase input to the single-phase output at the intersection. Normally, the matrix converter is fed by a voltage source and, for this reason the input terminals should not be short circuited. On the other hand, the load has typically an inductive nature and, for this reason, an output phase must never be opened.

      Fig. 1. Basic Circuit of Single Phase Matrix Converter

      The Single phase matrix converter circuit as shown in Fig 1 uses four bi-directional switches for the implementation of sin-gle phase Cycloconverter. It requires the use of bi-directional switches capable of blocking voltage and conducting current in both directions. Unfortunately there is no discrete semicon-ductor device. Currently that could be fullling the needs and hence the use of common-emitter anti-parallel IGBT, diode pair as shown in Fig 2 . Diodes are in place to provide reverse blocking capability to the switching module. The IGBT were used due to its high switching capabilities and high current carrying capabilities desirable amongst researchers for high power applications.

   2. Control Strategy

      To enable a Single Phase Matrix Converter (SPMC) to function as a cycloconverter, driver circuits are designed to generate specic control pulses for the power switches (IGBTs). In this implementation, pulse generation is achieved using MATLAB/Simulink (MLS) via pulse generator blocks and logic gates.The SPMC architecture consists of four bidi-rectional switches (S1 to S4). Each switch is labeled with

      Fig. 2. Schematic view of Bi-directional switch (common – emitter)

      a or b markers to denote the current ow direction: a: Forward direction.b: opposite direction.

      1. Step-Down Operation (25Hz and 12.5Hz)

         With an input frequency of 50Hz, the desired output fre-quencies are synthesized at 25Hz and 12.5Hz by sequencing the gate triggering pulses.

         As shown in gure 3 the biasing and triggering logic for the load cycles are as follows: Biasing ConditionsPositive Input Half-Cycle: Switches S1a, S2b, S3b, and S4a are for-ward biased. Negative Input Half-Cycle: Switches S1b, S2a, S3a, and S4b are forward biased. Triggering Logic for Load SynthesisTo obtain a positive load cycle:During the positive input half-cycle: Trigger S1a and S4a. During the negative input half-cycle: Trigger S3a and S2a. To obtain a negative load cycle:During the positive input half-cycle: Trigger S2b and S3b. During the negative input half-cycle: Trigger S4b and S1b. in Table 1 The specic sequence of these states over various time intervals determines the nal output frequency.

         Fig. 3. Different states for the operation of the Cycloconverter

      2. Step-Up Operation (100Hz and 150Hz)

   For step-up operation, the output frequency is synthesized as multiples of the 50Hz input (e.g., 100Hz and 150Hz). This

   TABLE I

   Switching Sequence of stepdown Cycloconverter

   requires higher-frequency switching within each input half-cycle. Commutation and Safety A critical aspect of the SPMC is safe commutation to handle inductive loads.

   Control Mechanism: During a positive supply voltage (e.g., at 50Hz output synthesis), S4a acts as the primary controlling switch. Continuous Conduction: S1a and S2a are maintained in a continuously ON state during this cycle. S1a completes the loop for output synthesis. S2a acts in conjunction with S1a to provide a freewheeling path whenever S4a is turned OFF. Dead-time Period: The commutation period is designed to extend over the dead-time. This allows stored energy to dissipate, effectively eliminating current reversals caused by inductive loads.

   TABLE II

   Switching Sequence of stepup Cycloconverter

   The proposed single-phase cycloconverter based on Single-Phase Matrix Converter (SPMC) topology eliminates the drawbacks of conventional thyristor-based designs by offering direct AC-AC conversion without a DC link. The switching

   strategy of stepdown cycloconverter and stepup cycloconverter had discussed. This control strategy overcomes the inherent limitations of conventional thyristor cycloconverters and fully exploits the advantages of matrix converter topology, deliver-ing superior waveform quality, extended frequency range, and safe operation.

   B. For an induction motor as load

   Given:

   • Rated power = 0.25 HP

   • Rated Voltage = 230 V

   • Input Frequency = 50 Hz

     12

   • ring angle: = 15 =

4. Mathematical Modelling

   A cycloconverter is a direct frequency converter that con-verts a xed AC voltage and xed frequency (e.g., 50/60

   • Vin,rms = 230V

   V

   orms

   = Vin

   1

   /

   (9)

   Hz) directly into a variable AC voltage at a lower output frequency without an intermediate DC link. It is essentially a collection of controlled thyristor (SCR) rectiers connected

   Vorms

   /

   = 230 1 1

   12

   = 220.1V (10)

   in anti-parallel (back-to-back) to produce positive and negative half-cycles of the output waveform.

   Types of Cycloconverters

   • Step-down cycloconverter: Output frequency fo¡fs(input supply frequency). Uses natural commutation (line com-mutation) of thyristors, making it simpler and more common for applications like low-speed drives.

   • Step-up cycloconverter : fo¿fs. Requires forced com-mutation to turn off thyristors prematurely, which adds complexity and is less practical due to poor waveform quality and higher harmonics.

   The calculations are done by considering the formulas of conventional cycloconverter. This analytical foundation sup-ports accurate simulation in Simulink, provides insight into harmonic performance and switching constraints.

5. Simulation Model

   1. For a resistive load

      Vo(avg)

      = 2Vm cos (1)

      Io(avg)

      V = V

      = Vo

      R

      /1

      (2)

      (3)

      orms in

      Iorms

      = Vorms = 3.25A (4)

      R

      Fig. 4. Simulation circuit of matrix converter as cycloconverter with R load

      Example Calculation Given:

      • Input Voltage = 230V

      • Frequency = 50Hz

      • Resistance = 50

        The system is tested under:

        • Resistive Load

        • Induction Motor Load

      A. Simulation circuit of Matrix converter with R load

      The switching sequences for the Single Phase Matrix Converter (SPMC) are synthesized using a pulse-generator-

      Vo(avg)

      690

      = = 146.422V (5)

      based control scheme. This system utilizes four bidirectional switches (S ,S ,S ,S ), each realized using a common-

      1 2 3 4

      Io(avg) =

      146.422

      50

      = 2.92A (6)

      emitter conguration of two IGBTs and two anti-parallel diodes. This arrangement is essential for blocking voltage and conducting current in both directions within the matrix-like

      / 1 structure.

      Vorms = 162.6

      1

      162.6

      = 162.634V (7)

      • Pulse Generation and Timing The control pulses are gen-eated through two primary pulse generator blocks within the simulation environment. The timing parameters are

        Iorms =

        = 3.25A (8)

        50

        dened as follows:

      • Time Period: Calculated based on the desired output frequency (e.g., for 100Hz and 150Hz operations as per Table 2).

      • Duty Cycle: The pulse width is xed at 50

      • Logic Synthesis: NOT gate blocks are utilized to com-plement the primary pulse generator outputs, ensuring synchronized gate signals for the bidirectional switch pairs.

      • Switching Topology : The matrix conguration facilitates direct AC-AC conversion by routing the input cycles to the load as follows:S1 and S3: Responsible for connecting the positive input cycle to the load terminals. S2 and S4: Congured to manage the negative input cycle transitions.

      • Operational Principle and Load The system is designed to provide a controlled AC output from a xed AC input voltage. By precisely modulating the ON and OFF intervals of the gate pulses, the output frequency and volt-age magnitude are adjusted to meet the requirements of the connected load. To simulate industrial performance, the model is tested using:

      • Resistive (R) Load

      • Induction Motor Load: To evaluate the converters effec-tiveness in speed control and torque performance under real-world conditions.

   2. Simulation circuit of matrix converter with Induction motor load

   In the gure 5 and gure 6 circuit conguration remains unchanged however, the load is replaced with an induction mo-tor to examine the effects of step-up and step-down frequency variations on its performance respectively. This modication provides a practical perspective on the application of the system. The specications of the induction motor used are: rated power of 0.25 HP, rated voltage of 230 V, and rated current in the range of 1.21.6 A.

   Fig. 5. Simulation circuit of matrix converter as cycloconverter with Single Phase Induction Motor load(25 Hertz stepdown cycloconverter )

   The output voltage waveforms are observed to analyze the system performance under varying operating conditions. In addition, the input RMS voltage and output RMS voltage

   are measured using display blocks, enabling a quantitative comparison of voltage levels across the system.

   Fig. 6. Simulation circuit of matrix converter as cycloconverter with Single Phase Induction Motor load(100 Hertz stepup cycloconverter )

   The proposed matrix converter is implemented as a cy-cloconverter using MATLAB/Simulink. The model provides detailed information on the Simulink block diagram and the key components used in its design. In the present implemen-tation, pulse generator-based control with NOT gate blocks is employed to generate gating pulses.

6. Results and Discussion

   The simulation results are summarized and provides a de-tailed performance analysis of the single-phase cycloconverter implemented using a matrix converter topology in Simulink

   .The converter is tested with a range of load variations and different frequencies. The system performance is assessed by observing key output parameters such as output voltage, cur-rent, speed, and torque of induction motor. These parameters are monitored using scope and display blocks.

   1. R Load Output

      For the given circuit, the input voltage has a frequency of 50 Hz and a peak voltage of 230 V.

      In Figure 7, the rst waveform represents the input voltage (50 Hz). The second waveform represents the output voltage. In this case, one positive half-cycle of the output is obtained for each full cycle of the input. This means that for every two input cycles, we get one complete output cycle. Therefore, the output frequency is reduced to 25 Hz, which is half of the input frequency. As a result, the time period increases, since frequency and time period are inversely proportional.

      In Figure 8, the rst waveform again represents the input voltage (50 Hz, 230 V peak voltage ). The second waveform is the output voltage. Here, one full cycle of the output is obtained from each half-cycle of the input. This means that for every one input cycle, we get two output cycles. Therefore, the output frequency is increased to 100 Hz, which is twice

      Fig. 7. Input and Output voltage waveforms of stepdown cycloconverter(R load)

      Fig. 8. Input and Output voltage waveforms of stepup cycloconverter(R load)

      the input frequency. Consequently, the time period decreases, again due to the inverse relationship between frequency and time period.

   2. Induction motor Load Output

      In this setup, the load is a single phase induction motor. The input RMS voltage supplied to the circuit is 230 V. In the case of step-down frequency operation, the output RMS voltage from the cycloconverter is 227.1 V, which is applied to the motor as its input voltage. In the case of step-up frequency operation, the output RMS voltage from the cycloconverter is

      228.6 V maintained close to the input value and is applied to the motor.

      The gure 9 shows both the input and output voltage wave-forms of the step-down cycloconverter. The output waveform has a lower frequency than the input, corresponding to the step-down operation, while maintaining nearly the same RMS voltage level. Similarly, The gure 10 shows both the input and output voltage waveforms of the step-up cycloconverter. The output waveform has a higher frequency than the input, corresponding to the step-up operation, while maintaining nearly the same RMS voltage level.

   3. Induction Motor Performance

      From the induction motor by using bus selector we have selected Rotor speed, Electromagnetic Torque, Main winding

      Fig. 9. Output voltage waveform of stepdown cycloconverter(Induction motor load)

      Fig. 10. Output voltage waveform of stepup cycloconverter(Induction motor load)

      Current given to the scope block.

      • In practical operation, an induction motor does not run exactly at synchronous speed but slightly below it due to a phenomenon called slip. Rotor Speed , N = Ns(1-s) where s is the slip Ns is the synchronous speed

      • The supply frequency directly affects the rotor speed of an induction motor because the rotor speed follows the rotating magnetic eld produced by the stator. In the gure 11 when the frequency decreases, the rotating magnetic eld slows down, and the rotor speed decreases.

      • Similarly, In the gure 12 When the frequency increases, the rotating magnetic eld in the stator rotates faster, causing the rotor to also speed up However, the rotor never reaches the exact speed of the rotating eld; it always runs slightly slower due to slip, which is necessary for torque production in the motor.

      • When the frequency decreases, the synchronous speed re-duces and slip increases, which can increase rotor current and torque demand. However, the main winding reactance also decreases, leading to a higher main winding current for the same applied voltage. It is shown in the gure 11.

      • When the supply frequency increases, the synchronous speed increases, which reduces the slip for a given

        rotor speed. This reduces the induced rotor current and therefore affects the electromagnetic torque.

      • At the same time, the stator (main winding) inductive reactance X = 2n increases with frequency, which in-creases the overall impedance of the main winding. As a result, the main winding current generally decreases at higher frequencies if the applied voltage is kept constant. These changes are shown in the gure 12

        which affects torque smoohness, increases losses, and may slightly impact efciency.

   4. Comparative Analysis

   The performance improvements against proposed method are quantied in Table III.

   TABLE III

   Comprehensive Performance Comparison of conventional cycloconverter and proposed SPMC

   Parameter	Conventional Thyristor	Proposed SPMC
   DC Link	Not required	Not required
   Output Frequency Range	fs/3	Up to fs/2 (theoretically)
   I/O Waveform Quality	High low-order harmonics	Near sinusoidal with PWM
   Input Power Factor	Poor and load dependent	Near unity and controllable
   Number of Power Switches	4 Thyristors	4 Bidirectional switches
   Commutation Strategy	Line (natural)	Forced (four-step or semi-soft)
   Reactive Components	Large output lter	Minimal ltering needed

   Fig. 11. output waveforms of single phase induction motor (25 hertz stepdown cycloconverter)

   Fig. 12. output waveforms of single phase induction motor (100 hertz stepup cycloconverter)

   From the analysis of different loads such as R load,and single-phase induction motor load, the performance of the cycloconverter has been successfully evaluated. For purely resistive (R) load, the output voltage closely follows the expected stepped frequency operation with minimal distortion.

   For the single-phase induction motor load, the cyclocon-verter effectively controls the supply frequency, which directly inuences the rotor speed of the motor. It is observed that a reduction in frequency leads to a decrease in motor speed, while an increase in frequency results in higher speed. However, due to the non-sinusoidal nature of the output waveform, harmonic distortion is present,

   The SPMC-based cycloconverter extends the frequency range beyond the traditional fs/3 limit while achiev-ing near-unity input power factor and near-sinusoidal waveforms.The design eliminates the bulky ltering and low-order harmonics inherent in thyristor-based systems. This transition results in a more compact, efcient, and precisely controllable AC-AC power conversion topology.

7. Conclusion and Future Scope

1. Conclusion

   The cycloconverter-based matrix converter has been suc-cessfully implemented, and analyzed for different types of loads such as R, RLC, and single-phase induction motor. The results demonstrate that the cycloconverter is capable of converting a xed input frequency into variable output frequencies in both step-down and step-up modes. For resistive and RLC loads, the output waveforms follow the expected frequency conversion, though some distortion is observed due to switching action and the presence of reactive components.

   For the single-phase induction motor load, it is observed that the variation in output frequency directly controls the rotor speed of the motor. A decrease in frequency results reduction in motor speed, while an increase in frequency leads to higher speed operation. However, the non-sinusoidal nature of the output waveform introduces harmonic distortion, which affects torque smoothness, increases losses, and slightly reduces overall efciency. Despite these limitations, the system effectively demon-strates frequency-based speed control of induction mo-tors.

   Hence the developed single phase cycloconverter based matrix converter topology offers signicant advantages, as it acts as a universal power converter capable of recti-er, inverter , chopper ,and cycloconverter conversions. It nds wide applications in motor drives, renewable energy

   systems such as wind and solar power, electric vehicles, and aerospace systems. The simulation results conrm that the matrix-based cycloconverter provides better per-formance in terms of compact design and efcient power conversion.

2. Future Scope

In future,the performance of the cycloconverter system can be further improved by implementing advanced con-trol techniques such as PWM-based switching methods , space vector modulation to reduce harmonic distortion.

References

1. Maxym Vorobyov, Overview of Single Phase Matrix Converter Applications

2. Zuckerberger, A., Weinstock, D., Alexandrovitz A., Single-phaseMatrix Converter, IEE Proc.Electric Power App, Vol.144(4), Jul 1997 pp 235-240.

3. Modelling Simulation of Single-phase Matrix Converter as a Fre-quency Changer with Sinusoidal Pulse Width Modulation Using MATLAB/Simulink ,Conference: Power and Energy Conference, 2006. PECon 06. IEEE International.

4. B. R. Pelly, Thyristor Phase-Controlled Converters and Cyclocon-verters, Wiley, New York, 1971.

5. Zahirruddin Idris, siti Zaliha mahammud noor, Mustafar kamal HamzaSafe Commutation Strategy in Single Phase Matrix Con-verter IEEE PEDS 2005 Conference.

6. Hosseini, S.H.; Babaei, E, A new generalized direct matrix converter, Industrial Electronics, 2001. Proc. ISIE 2001. Vol(2)

   , 2001 pplO71-1076.

7. Wheeler, P.W., Rodriguez, J., Clare, J.C., Empringham, L., Wein-stein, A., Matrix converters: a technology review, IEEE Transac-tion on Industrial Electronics, Vol. 49(2), April 2002,pp. 276-288.

8. P. Deivasundari and V, Jamuna, Single phase matrix converter as an all silicon solution, Journal of Electrical Engineering, Vol. 11, no. 3,2011.

9. Maamoun, A., Development of cycloconverters, Canadian Con-ference (1), Jan-Feb2004, pp. 59- 65.on Electrcal and Computer Engineering, 2003. IEEE CCECE 2003.

10. Wheeler, P.W., iguez, J., Clare, J.C., Empringham L, Wein-stein,Vol.1, 4-7 May 2003, pp. 521 -524 A., Matrix converters: a technology review, IEEE Transactions