Buck Matrix Converter with High-Frequency Transformer Isolation and Reduced Switch Count

ABSTRACT:

In this paper, a new type of matrix converter also called a single-phase high-frequency transformer  isolated (HFTI) buck matrix converter (MC) is proposed. The proposed converter can provide step-down operation of the input voltage with various types of output voltages such as; in-phase and out-of-phase output voltages, rectified (or positive) output voltage, and output voltage with step-changed frequency. By incorporating HFT isolation, the proposed MC saves an extra bulky line frequency transformer, which is required for the conventional MCs to provide electrical isolation and safety, when used in application such as dynamic voltage restorers (DVRs), etc.

INDUCTOR

Two different circuit variations of the proposed HFTI MC are presented with and without  continuous output currents, with the latter having less passive components. The safe-commutation strategy is also employed for the proposed HFTI MC to provide current path for the inductor during dead-time, which avoids switch voltage spikes without adding any snubber circuits. The operation principle and circuit analysis of the  proposed MC are presented, and switching strategies are also developed to obtain various output voltages. Moreover, a prototype of the proposed MC is fabricated, and experiments are performed to produce in-phase/out-of-phase and rectified output voltages, and output voltage with step-changed frequency.

KEYWORDS:

  1. High-frequency transformer
  2. In-phase and out-of-phase operations
  3. Rectified output
  4. Single-phase matrix converter
  5. Step-changed frequency

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, a buck MC is proposed with HFT isolation. The proposed MC is capable of providing various types of output voltages, such as in-phase, out-of-phase and rectified output voltages. Moreover, the frequency of the output voltage can be changed in steps, so that it is integer multiple or integer fraction of the input voltage frequency. The use of HFT isolation in the proposed MC for electrical isolation and safety benefits in that it removes the need for extra bulky line frequency transformer, which is added with conventional non-isolated MCs for applications as DVRs. Two different secondary side structures of the proposed HFTI buck MC are proposed, with one having continuous output current, and the other having discontinuous out current but with one inductor and capacitor less. The soft-commutation strategy is suggested for the proposed MC, which avoids switch voltage spikes without using any snubber circuits. The operation principle and circuit analysis of the proposed converter are presented and switching strategies are also developed to obtain various output voltages. Moreover, a 200 W laboratory prototype of the proposed MC is fabricated, and experiments are performed to produce in-phase/out-of-phase and rectified output voltages, and output voltage with step-changed frequency.

REFERENCES:

[1] F. Z. Peng, L. Chen, and F. Zhang, “Simple topologies of PWM ac-ac converters,” IEEE Power Electron. Letters, vol. 1, no. 1, pp. 10– 13, Mar.

2003.

[2] T. B. Lazzarin, R. L. Andersen, and I. Barbi, “A switched-capacitor three-phase ac-ac converter,” IEEE Trans. Ind. Electron., vol. 62, no. 2,

  1. 735–745, Feb. 2015.

[3] H. F. Ahmed, H. Cha, A. A. Khan, and H.-G. Kim, “A family of high-frequency isolated single-phase Z-source ac-ac converters with safe-commutation strategy,” IEEE Trans. Power Electron., vol. 31, no. 11, pp. 7522–7533, Nov. 2016.

[4] C. Liu, B. Wu, N. R. Zargari, D. Xu and J. Wang, “A novel three-phase three-leg ac-ac converter using nine IGBTs,” IEEE Trans. Power Electron., vol. 24, no. 5, pp. 1151–1160, May. 2009.

[5] C. B. Jacobina, I. S. d. Freitas, E. R. C. d. Silva, A. M. N. Lima, and R. L.A. Riberio, “Reduced switch count dc-link ac-ac five-leg converter,”

IEEE Trans. Power Electron., vol. 21, no. 5, pp. 1301–1310, Sep. 2006.

A New PWM and Commutation Scheme for One Phase Loss Operation of Three- Phase Isolated Buck Matrix-Type Rectifier

ABSTRACT:

The PWM paper, another PWM plan and substitution technique is exhibited for one stage misfortune task of three-stage detached buck network type rectifier. With the proposed PWM conspire, the most extreme passable voltage gain for one stage misfortune task can be accomplished, which allows the nonstop activity of the converter to convey 2/3 of evaluated influence and manage the yield voltage with greatest yield voltage drop under 5% of ostensible yield voltage.

Three phase isolated buck matrix  type matrix paper, with the proposed remuneration procedure, a shielded change from one phase disaster assignment to normal movement and the other path around can occur with least substitution steps (two-advance) under zero voltage exchanging (ZVS) condition. The execution of the proposed PWM plan and reward plans with one phase disaster movement is evaluated and checked by generations and preliminaries on a 5kW model.

CIRCUIT DIAGRAM:

 

Fig. 1. ZVS three-phase PWM rectifier.

EXPECTED SIMULATION RESULTS:

 

 Fig. 2. Simulated waveforms for 2/3PO_max, vLL = 480V and ma = 0.75 when “phase C” is shorted at t1 and recovered at t2: (a) input phase voltages, (b) input phase currents, (c) transformer secondary voltage, (d) output of bridge rectifier, (e) output voltage and battery set point, (f) output inductor current.

 CONCLUSION:

In this paper, errand of the three-arrange isolated Buck matrix type rectifier under one phase setback condition is depicted and another. PWM plan and pay technique for the one phase adversity action is proposed. With the proposed trading plan and remuneration method, two phase supplanting with ZVS (here either using ZVS or zero voltage turn-ON). Can be recognized for one phase incident action and besides for the change from run of the mill assignment to one phase disaster movement and from one phase setback errand to common action. Undertaking and execution of the converter with the proposed PWM and substitution method are affirmed with reenactment and preliminary outcomes.

In perspective on the preliminary outcomes obtained from a 5 Kw model, it is exhibited that the converter .Can pass on 2/3 of most outrageous yield ability to the load and direct the yield voltage with most prominent voltage drop under 5% of apparent yield voltage. Current stress of the converter and data current .THD and range examination are in like manner outfitted in the test results with one phase mishap movement. The by and large huge THD (around 40%) is one of the drawbacks for this converter while working under one phase adversity condition.

Reactive Power Control of Permanent-Magnet Synchronous Wind Generator With Matrix Converter

 ABSTRACT:

In this paper, the reactive power control of a variable speed permanent-magnet synchronous wind generator with a matrix converter at the grid side is improved. A generalized modulation technique based on singular value decomposition of the modulation matrix is used to model different modulation techniques and investigate their corresponding input reactive power capability. Based on this modulation technique, a new control method is proposed for the matrix converter which uses active and reactive parts of the generator current to increase the control capability of the grid-side reactive current compared to conventional modulation methods. A new control structure is also proposed which can control the matrix converter and generator reactive current to improve the grid-side maximum achievable reactive power for all wind speeds and power conditions. Simulation results prove the performance of the proposed system for different generator output powers.

KEYWORDS:

  1. Matrix converter
  2. Permanent-magnet synchronous generator (PMSG)
  3. Reactive power control
  4. Singular value decomposition (SVD) modulation
  5. Variable-speed wind generator

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. Simplified control block diagram of a PMSG.

EXPECTED SIMULATION RESULTS:

Fig. 2. Generator-side active and reactive power and the maximum grid side

reactive power versus generator shaft speed  ɷm for different strategies.

Fig. 3. Matrix converter grid-side reactive power and the generator direct axis current (Igd) , terminal voltage and losses for ɷm = 1 rad/s.

Fig. 4. Matrix converter grid-side reactive power and the generator direct axis

Current (Igd) , terminal voltage, and losses for ɷm = 4.5 rad/s.

 CONCLUSION:

In this paper, a new control strategy is proposed to increase the maximum achievable grid-side reactive power of a matrix converter-fed PMS wind generator. Different methods for controlling a matrix converter input reactive power are investigated. It is shown that in some modulation methods, the grid-side reactive current is made from the reactive part of the generator-side current. In other modulation techniques, the grid-side reactive current is made from the active part of the generator-side current. In the proposed method, which is based on a generalized SVD modulation method, the grid-side reactive current is made from both active and reactive parts of the generator-side current. In existing strategies, a decrease in the generator speed and output active and reactive power, will decrease the grid-side reactive power capability. A new control structure is proposed which uses the free capacity of the generator reactive power to increase the maximum achievable grid-side reactive power. Simulation results for a case study show an increase in the grid side reactive power at all wind speeds if the proposed method is employed.

 REFERENCES:

[1] P. W.Wheeler, J. Rodríguez, J. C. Clare, L. Empringham, and A.Weinstein, “Matrix converters: A technology review,” IEEE Trans. Ind. Electron., vol. 49, no. 2, pp. 276–288, Apr. 2002.

[2] L. Zhang, C. Watthanasarn, and W. Shepherd, “Application of a matrix converter for the power control of a variable-speed wind-turbine driving a doubly-fed induction generator,” Proc. IEEE IECON, vol. 2, pp. 906–911, Nov. 1997.

[3] L. Zhang and C.Watthanasarn, “A matrix converter excited doubly-fed induction machine as a wind power generator,” in Proc. Inst. Eng. Technol. Power Electron. Variable Speed Drives Conf., Sep. 21–23, 1998, pp. 532–537.

[4] R. CárdenasI, R. Penal, P. Wheeler, J. Clare, and R. Blasco-Gimenez, “Control of a grid-connected variable speed wecs based on an induction generator fed by a matrix converter,” Proc. Inst. Eng. Technol. PEMD, pp. 55–59, 2008.

[5] S. M. Barakati, M. Kazerani, S. Member, and X. Chen, “A new wind turbine generation system based on matrix converter,” in Proc. IEEE Power Eng. Soc. Gen. Meeting, Jun. 12–16, 2005, vol. 3, pp. 2083–2089.

Analysis and Mathematical Modelling Of Space Vector Modulated Direct Controlled Matrix Converter

ABSTRACT:

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. This paper presents the work carried out in developing a mathematical model for a space vector modulated (SVM) direct controlled matrix converter. The mathematical expressions relating the input and output of the three phase matrix converter are implemented by using MATLAB/SIMULINK. The duty cycles of the switches are modeled using space vector modulation for 0.5 and 0.866 voltage transfer ratios. Simulations of the matrix converter loaded by passive RL load and active induction motor are performed. A unique feature of the proposed model is that it requires very less computation time and less memory compared to the power circuit realized by using actual switches. In addition, it offers better spectral performances, full control of the input power factor, fully utilization of input voltages, improve modulation performance and output voltage close to sinusoidal.

KEYWORDS:

  1. Matrix Converter
  2. Space Vector Modulation
  3. Simulation Model
  4. Induction Motor

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

image001

Figure 1: Block diagram of simulation model for direct matrix converter

EXPECTED SIMULATION RESULTS:
image002

Figure 2: Result for sector identification

image003

Figure 3: Input and output voltage with passive load for q=0.5; R=135.95Ω, L=168.15mH, Vim=100 V, fo = 60Hz, fs = 2kHz

image004

Figure 4: Input and output voltage with passive load for q=0.866; R=135.95Ω, L=168.15mH, Vim=100 V, fo = 60Hz, fs = 2kHz

 image005

 Figure 5: Input and output voltage with loaded induction motor for q=0.5; 3hp, Rs =0.277Ω, Rr=0.183Ω, Nr=1766.9rpm, Lm=0.0538H, Lr=0.05606H, Ls=0.0533H,fo=60Hz, fs=2kHz

image006

Figure 6: Input and output voltage with loaded induction motor for q=0.866; 3hp, Rs =0.277Ω, Rr=0.183Ω, Nr=1766.9rpm, Lm=0.0538H, Lr=0.05606H, Ls=0.0533H, fo=60Hz, fs=2kHz
image007

Figure 7: Input current with passive load; R=135.95Ω, L=168.15mH, Vim=100 V, fo = 60Hz, fs = 2kHz (a) q=0.5, (b) q = 0.866
image008

 Figure 8: Input current with loaded induction motor for q=0.866; 3hp, Rs =0.277Ω, Rr=0.183Ω, Nr=1766.9rpm, Lm=0.0538H, Lr=0.05606H, Ls=0.0533H, fo=60Hz, fs=2kHz

 CONCLUSION:

The main constraint in the theoretical study of matrix converter control is the computation time it takes for the simulation. This constraint has been overcome by the mathematical model that resembles the operation of power conversion stage of matrix converter. This makes the future research on matrix converter easy and prosperous. The operation of direct control matrix converter was analysed using mathematical model with induction motor load for 0.866 voltage transfer ratio.

 REFERENCES:

[1]. A. Alesina, M.G.B.V., Analysis And Design Of Optimum-Amplitude Nine – Switch Direct AC-AC Converters. IEEE Trans. On Power. Electronic, 1989. 4.

[2]. D. Casadei, G.S., A. Tani, L. Zari, Matrix Converters Modulation Strategies : A New General Approach Based On Space-Vector Representation Of The Switch State. IEEE Trans. On Industrial Electronic, 2002. 49(2).

[3]. P. W. Wheeler, J.R., J. C. Claire, L. Empringham, A. Weinstein, Matrix Converters : A Technology Review. IEEE Trans. On Industrial Electronic, 2002. 49(2).

[4]. H. Hara, E.Y., M. Zenke, J.K. Kang, T. Kume. An Improvement Of Output Voltage Control Performance For Low Voltage Region Of Matrix Converter. In Proc 2004 Japan Industry Applications Society Conference, No. 1-48, 2004. (In Japanese). 2004

[5]. Ito J, S.I., Ohgushi H, Sato K, Odaka A, Eguchi N., A Control Method For Matrix Converter Based On Virtual Ac/Dc/Ac Conversion Using Carrier Comparison Method. Trans Iee Japan Ia 2004. 124-D: P. 457–463.