Implementation of Single-Phase Two-Switch Midpoint Unidirectional Multilevel Converter System

Author(s):  
Peethala Rajiv Roy ◽  
P. Parthiban ◽  
B. Chitti Babu

Abstract This paper deals with implementation of a single-phase three level converter system under low voltage condition. The frequency of the switches is made constant and involves change in ${t_{on}}$ and ${t_{off}}$ duration. For this condition the pulse width modulation control scheme for a single phase three level rectifier is developed to improve the power quality. The hysteresis current control technique is adopted to bring forth three-level PWM on the dc side of the bridge rectifier and to achieve high power factor and low harmonic distortion. Based on the proposed control scheme, the line current is driven to follow the sinusoidal current command which is in phase with the supply voltage. By using three-level voltage pattern the blocking voltage of each power device is clamped to half of the dc link voltage. The simulation and experimental results of 20W converter under low input voltage condition are shown to verify the circuit performance. Open loop simulation and hardware tests are implemented by applying a low voltage of 15 V(rms) on the input side.

2019 ◽  
Vol 3 (1) ◽  
pp. 21-27
Author(s):  
Francis Mulolani ◽  
Francis Kafata ◽  
Esau Zulu

This paper presents the design and closed-loop current control of a grid connected seven-level, 3-phase diode-clamped multilevel inverter for Photovoltaic (PV) applications. The proposed closed loop current control technique is based on the voltage-oriented proportional integral (PI) controller theory. The modulation technique used is level-shifted-carrier sinusoidal pulse width modulation (SPWM). The gain values of PI controller were selected to achieve good current quality and dynamic response. Grid synchronization was achieved by using a synchronous-reference frame phase-locked loop (SRF-PLL). Matlab/Simulink was used for the control system design and simulation. The simulation results show that a 1.34% total harmonic distortion (THD) of the output current was achieved which is within the allowable current distortion limits by international standards. The stability of the system was analyzed using pole-zero mapping and root locus.


Author(s):  
Taha A. Hussein ◽  
Laith A. Mohammed

Space vector pulse width modulation (SVPWM) generates less harmonic distortion in the output voltage or currents, provides more efficient use of supply voltage and better voltage utilization compared with sine pulse width modulation (PWM). In this work, a detailed Simulink implementation for SVPWM for the open loop control of permanent magnet synchronous motor (PMSM) is presented. Results show the output of the blocks that assembles SVPWM besides the PMSM voltages and currents when exposing the motor to different load torques. The technique of SVPWM enables the load to respond to the change in external load torque. This technique also results in lower total harmonic distortion and better utilization of the direct current (DC) supply compared with traditional sinusoidal pulse width modulation sinusoidal pulse width modulation (SPWM).


Author(s):  
Linda Hassaine ◽  
Mohamed Rida Bengourina

The power quality injected into the grid and the performance of the converter system depend on the quality of the inverter current control. This paper proposes a design and control technique for a photovoltaic inverter connected to the grid based on the digital pulse-width modulation (DSPWM) which can synchronise a sinusoidal output current with a grid voltage and control a power factor. The current injected must be sinusoidal with reduced harmonic distortion. The connected PV system is based on H-Bridge inverter controlled by bipolar PWM Switching. The current control technique and functional structure of this system are presented and simulated. Detailed analysis, Simulations results of output voltage and current waveform demonstrate the contribution of this approach to determinate the suitable control of the system. A digital design of a generator PWM using VHDL is proposed and implemented on an Xilinx FPGA and it has been validated with experimental results. As a result, the proposed inverter implementation is simple, and it becomes an attractive solution for low power grid connected applications.


Author(s):  
Kureve D. Teryima ◽  
Goshwe Y. Nentawe ◽  
Agbo O. David

<p>This paper proposes a switching control for a cascaded H-bridge inverter structure with reduced switches which is used to improve the THD performance of a single phase five level CHB MLI. The multi level inverter is simulated for the conventional carrier overlapping APOD and the proposed carrier overlapping APOD Pulse Width Modulation (PWM) switching control technique. The total harmonic distortion (THD) of the output voltages are observed for both PWM control techniques. The performance of the symmetric CHB MLI is simulated using MATLAB-SIMULINK. It is observed that the proposed carrier overlapping APODPWM provides output with relatively low THD as compared to the conventional carrier overlapping APODPWM.</p>


Author(s):  
Fanyang Li ◽  
Tao Yang

A driving amplifier capable of operating at a minimum voltage is proposed, aiming to subdue the distortion effect caused by large amplitude driving at the hearing aid loudspeaker. Since the linearity of a cascode amplifier usually degrades with the reduced supply voltage, a three-stage cascade amplifier having a parallel cascade second stage, and a folded cascade Class-AB output current control in place are designed. With such an arrangement, the open loop gain should still be maintained at a sufficiently high level even in the presence of increased output amplitude. Also, the minimum supply voltage required can then be reduced to merely [Formula: see text]. Fabricated on a 0.18[Formula: see text][Formula: see text]m complementary metal oxide semiconductor (CMOS) process, the proposed amplifier achieves [Formula: see text][Formula: see text]dB total harmonic distortion [Formula: see text] with a loudspeaker load of 100[Formula: see text]ohm while operating from a 1.2[Formula: see text]V supply and being subject to a 1[Formula: see text]kHz sinusoidal input.


Author(s):  
Kureve D. Teryima ◽  
Goshwe Y. Nentawe ◽  
Agbo O. David

This paper proposes a switching control for a cascaded H-bridge inverter structure with reduced switches which is used to improve the THD performance of a single phase five level CHB MLI. The multi level inverter is simulated for the conventional carrier overlapping APOD and the proposed carrier overlapping APOD Pulse Width Modulation (PWM) switching control technique. The total harmonic distortion (THD) of the output voltages are observed for both PWM control techniques. The performance of the symmetric CHB MLI is simulated using MATLAB-SIMULINK. It is observed that the proposed carrier overlapping APODPWM provides output with relatively low THD as compared to the conventional carrier overlapping APODPWM.


Author(s):  
Md. Shamsul Arifin ◽  
Nur Mohammad ◽  
Mohammad Ibrahim Khalil ◽  
Mohammad Jahangir Alam

<span lang="EN-US">A new closed loop AC to DC ĈUK converter is presented in this paper. The conventional ĈUK AC to DC converter has no feedback circuit. Thereby, the output voltage of the converter changes while changing the load. The proposed closed loop converter can regulate voltage with the variation of load over a wide range. Moreover, the power factor and Total Harmonic Distortion (THD) of the supply side current found quite satisfactory from this closed loop ĈUK converter. The converter operates in four steps with a different combination of voltage polarities and switching states. The feedback path consists of a voltage control loop and a current control loop. The closed loop ĈUK converter in this study is compared with the open loop version. Additionally, the comparison is made with the conventional converter of the same topology. The effectiveness in terms of power factor and THD of the proposed converter is verified using simulation results.</span>


Author(s):  
Zeynep Bala Duranay ◽  
Hanifi Guldemir

Generally, AC-AC converters are implemented using thyristors. These converters generate harmonics and have a low power factor. To eliminate these problems matrix converters (MC) are become used as AC-AC converter. Matrix converters have the capability of being used as frequency changer, rectifier, inverter and chopper. In this work, it is proposed to achieve the desired output of AC-AC Boost converter using single phase matrix converter (SPMC). The operation of single-phase AC-AC boost converter using MC is studied in this paper. The output voltage of this boost converter is higher than the AC input supply voltage. insulated gate bipolar transistors (IGBTs) are used as the switching elements in the SPMC power circuit. Sinusoidal Pulse width modulation (SPWM) technique is applied to generate switching signals to obtain the output voltage. The model of the matrix converter is constructed in MATLAB/Simulink programming software package. The behavior of SPMC is simulated with various switching frequencies. The simulation results together with harmonic spectrum and total harmonic distortion (THD) values are presented. Successful operation of boost SPMC is achieved.


Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6060
Author(s):  
Wojciech Sleszynski ◽  
Artur Cichowski ◽  
Piotr Mysiak

The reported research aims at improving the quality of three-phase rectifier supply currents. An effective method consists of adding properly formed booster voltages to the fundamental supply voltages using a series active filter. In the proposed solution, the booster voltages are generated by three single-phase systems consisting of inverters, LC filters, and single-phase transformers. The application of LC couplings ensures low emission of disturbances, but may provoke compensator stability problems. The article presents the current control system for a series active filter designed to suppress the dominant harmonics in the supply currents of an 18-pulse rectifier, without interference into fundamental current components. A proportional control is proposed in combination with integral terms implemented in the orthogonal coordinate systems, which synchronically rotate with frequencies equal to those of the harmonic components to be eliminated. The use of complex gains in integral terms allows a simple phase correction of the output signals. A description is given of the method to determine controller parameters based on the mathematical model of the control object. Sample results of experimental tests performed in steady-state and transient conditions are included to illustrate the quality of performance of the series active filter as compared to the results recorded for the rectifier alone, and for the rectifier with additional line reactor. The applied control method of active filter significantly reduces harmonic distortion of the grid current, which is particularly advantageous at nonideal supply voltage and low loads.


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