Single-Phase Inverter Deadbeat Control with One-Carrier-Period Lag

This research compared the performance of PWM (Pulse Width Modulation) inverter and multilevel inverter in terms of their output voltage and current total harmonic distortion (THD). The inverters were designed to have the output voltage of 220 V at 50 Hz. The input voltage for both inverters are 400 VDC. For PWM inverter, the PWM technique utilized was sinusoidal PWM (SPWM) and for multilevel converter, the number of voltage level is five with diode-clamped topology. The study included circuit implementation, analysis, and THD calculation, all of which were carried out through simulation using PSpice software. In controlling the SPWM inverter output, the adjusted parameters included amplitude modulation ratio, frequency modulation ratio, and filter components’ parameters. On the other hand, the firing angles of the switching components were designated as controlling parameters in multilevel inverter. From the study, it was found that the best THD values of the designed SPWM inverter are 4.2% (voltage) and 1.7% (current), while those of multilevel inverter are 27% and 11%, for voltage and current, respectively. Thus, it can be concluded that SPWM inverter is better than 5-level inverter for the application in solar panel due to its lower THD. In our study, 5-level inverter did not satisfy the THD requirement specified in IEEE 512-1992, i.e. 5%.

In some applications of microgrids and distributed generation, it is necessary to feed islanded or stand-alone loads with high-quality voltage to provide low total harmonic distortion (THD). To fulfil these demands, an LC filter is usuallyconnected to the output terminals of power electronics converters. A cascaded voltage and current control loop with pulse-width modulation schemes are used to regulate the voltages and currents in these systems. However, these strategies have some drawbacks, particularly when multiple-input–multiple-output plants (MIMO) are controlled using single-input–single-output (SISO) design methods. This methodology usually produces a sluggish transient response and cross–coupling between different control loops and state variables. In this paper, a model predictive control (MPC) strategy based on the concept of optimal switching sequences (OSS) is designed to control voltage and current in an LC filter connected to a three-level neutral-point clamped converter. The strategy solves an optimisation problem to achieve control of the LC filter variables, i.e., currents and output voltages. Hardware-in-the-loop (HIL) results are obtained to validate the feasibility of the proposed strategy, using a PLECS–RT HIL platform and a dSPACE Microlab Box controller. In addition to the good dynamic performance of the proposed OSS–MPC, it is demonstrated using HIL results that the control algorithm is capable of obtaining low total harmonic distortion (THD) in the output voltage for different operating conditions.

Recently, great attention has been addressed for multilevel inverters, as they exhibit low total harmonic distortion (THD) in the output voltage and low electromagnetic interference (EMI). This paper proposes a single-phase five-level pulse width modulation (PWM) inverter for grid connection. The proposed PWM technique has some switches operated at fundamental line frequency and the others operate at inverter switching frequency. The proposed inverter has advantages of less number of components and low THD compared with the conventional multilevel inverter. The inverter operational principles and the switching functions are analyzed in this paper. Moreover, a proportional integral (PI) current control algorithm is designed and implemented in DSPACE DS1103 to keep the current injected into the grid sinusoidal and in-phase with the grid voltage for unity power factor. Simulation and experimental results prove the powerful merits of the proposed multi-level inverter and the capabilities of the proposed PWM technique.

This paper analyzes the Total Harmonic Distortion (THD) performance of a single phase 5-level CHB MLI. The multi level inverter is simulated using the carrier overlapping APOD Pulse Width Modulation (PWM) switching control technique. The total harmonic distortion (THD) of the output voltage is observed for the PWM control technique at varying modulation index of 0.7-1.0. The performance of a 5-level CHB MLI is simulated using MATLAB/SIMULINK. It is observed that the carrier overlapping APODPWM provides output with relatively low THD.

This paper presents a closed loop controller for bidirectional high-frequency link inverter. Deadbeat control is adopted to achieve fast dynamic response. The controller consists of inner current loop and outer voltage loop. To improve overall performance of the system, additional decoupling networks are employed. Output voltage decoupling network is included to improve the response of current loop; while load current decoupling network is used to increase the robustness of the inverter towards load variation. Simulation results are presented for the closed loop system under linear and nonlinear loads. It is shown that the control method provides good dynamic response with low total harmonic distortion, even under full-bridge rectifier loads.

Проведено огляд топологій інверторів напруги, що знаходять широке використання у системах електроживлення з альтернативними джерелами енергії, визначено переваги та недоліки кожної з топологій. Більш детально розглянуто будову та принцип функціонування інверторів з імпедансним та квазі-імпедансним ланцюгом у вхідному колі. Проведено порівняння багаторівневої каскадної топології, топології з імпедансним ланцюгом у вхідному контурі (z-інверторів), топології з квазі-імпедансним ланцюгом у вхідному контурі (квазі-z-інверторів), а також багаторівневих каскадних топологій з використанням z- та квазі-z-інверторів у якості топології силової частини окремого модуля за коефіцієнтом нелінійних спотворень вихідної напруги. За результатами отриманими в результаті досліджень наведено рекомендації щодо застосування досліджених топологій виходячи з вимог навантаження до якості вихідної напруги та типу використовуваного джерела альтернативної енергії.

In the present scenario, renewable energy source like solar power is the more convenient source of energy. Sustaining a steady DC link voltage and regulation of grid-current are challenging task in grid-tied photovoltaic (PV) system. These issues are overcome by designing a dual-loop control schemes; outer dc-link voltage loop which generates the reference signal for the inner current loop. The grid-tried inverter is used in photovoltaic (PV) system to inject the current with low total harmonic distortion (THD) into the utility grid by designing the efficient current controller. Generally, proportional-integral (PI) controller, proportional-resonant (PR) controller, dead-beat controller and hysteresis current controller are used in PV system to regulate the grid-current. These controllers are implemented in any one of the reference frames like; synchronous (d-q), stationary (α-β) or natural (a-b-c) reference frame. In this paper, the above-mentioned grid-current controllers are employed in all three reference frames and evaluate the steady-state performance of the controllers in terms of THD. The advantages and disadvantages of all grid-current controllers in each reference frames are briefly discussed and compared. This paper provides the best possible grid-current controller in three different reference frames. Finally, the simulation results from a two-stage 5.5 kW, 440 V (L-L), three-phase grid-tied PV system are provided to confirm the theoretical analysis and effectiveness of the control schemes.

In this paper, the mathematical model and work principle of the three-phase voltage source pulse width modulation (PWM) rectifier (VSR) are analyzed. Then, the control strategies without feed-forward and with feed-forward are compared, which based on the power factor, the total harmonic distortion (THD) and DC voltage stability. Voltage-Oriented Control (VOC) and direct current control method were adopted to obtain current tracking control. Meanwhile, a simplified algorithm was presented for space vector PWM (SVPWM), which simplifies the arithmetic process. Contrastive analysis of two control strategy results show that without feed-forward control strategy exits the faults of low power factor, high THD and so on, although its model is simple. While feed-forward control strategy has been proved more effective.

The aim of this paper is to obtain the AC voltage from DC source with the help of Space vector based Inverter. In a space-vector PWM (Pulse Width Modulation) inverter, which is widely used, the voltage utilization factor can be increased to 0.906, normalized to that of the six step operation. Three phase voltage-source pulse width modulation inverters have been widely used for dc/ac power conversion since they can produce a variable voltage and variable frequency power. However, they require a dead time to avoid the arm-short and snubber circuits to suppress the switching spike. Apart from these ancillary aspects, the PWM inverters have an essential problem that they cannot produce voltages as large as the six-step inverters can. That is, the dc bus voltage cannot be utilized to the maximum. To increase the voltage utilization of the sinusoidal PWM inverter, a method of the addition of the third harmonics to the reference voltage was proposed by which the fundamental component can be increased by 15.5%. In a space-vector PWM inverter, which is widely used, the voltage utilization factor can be increased to 0.906, normalized to that of the sixstep operation. On the other hand, different discontinuous PWM strategies were analyzed, where the modulation waveform of a phase has at least one segment of 60 which is clamped to the positive and/or negative dc bus for, at most, a total of 120 in a fundamental period during which no switching in either inverter arm occurs. Recently, it is shown that discontinuous PWM schemes and the space-vector PWM can be obtained by properly adding a zero-sequence voltage to the original modulation waveform.

This paper proposes an “active common-mode noise canceler” that is capable of eliminating the common-mode voltage produced by a voltage source PWM (pulsewidth modulated) inverter. It generates a compensating voltage which has the same amplitude as, but the opposite phase to, the common-mode voltage produced by the PWM inverter. The compensating voltage is superimposed on the inverter output by a common-mode transformer. As a result, the common-mode voltage applied to the load is canceled completely. The design method of the active common-mode noise canceler is also presented in detail. A prototype has been constructed and tested to verify the effectiveness for an induction motor drive system of 3.7 kW using an IGBT (insulated gate bipolar transistor) inverter. Some experimental results show that the proposed active common-mode noise canceler makes a significant contribution to eliminating the common-mode current or the ground current, and it prevents an electric shock from being received by anyone handling it. © 1998 Scripta Technica, Electr Eng Jpn, 124(3): 64–72, 1998

The authors present a novel topology for a single-phase PWM (pulse width modulation) inverter with sinusoidal output voltage at 50 Hz. The inverter is composed of power MOSFETs, fast recovery rectifying diodes, ferrite core transformers, and compact resonant filters tuned at 25 kHz switching frequency. It has high power-to-weight ratio, low total harmonic distortion, and good output voltage regulation for both input voltage and load current variations. The inverter is capable of operating at wide range of V/f ratios of the output voltage. The inverter can be used as a square wave inverter by giving a DC voltage as the modulating signal and commutating the relevant set of switches at the desired frequency. Inverter operation and the method of selecting power stage components are described, along with experimental results. >

In this study, an efficient technique to improve and maintain the voltage levels of Cascaded H-Bridge Multi-Level Inverter (CHB-MLI) which utilizing PhotoVoltaic (PV) panel sources is presented. It is designed to make fifteen level output voltage and tested under the various levels of resistive loads. It produces staircase output with reduced component size, increases the output voltage level, reduces the voltage stress across the load/switches, reduces the Total Harmonic Distortion (THD) and increases the voltage gain. The switching pulses are generated using Phase Opposition Disposition (POD)-Pulse Width Modulation (PWM) technique. It is modeled and simulated using SIMULINK graphical programming environment in MATLAB. Results prove that the system provides lower THD than conventional systems.

For medium- and high-power electronic application technologies, the three-level neutral-point-clamped (3L-NPC) inverter is an effective solution and modulation method is one of its research focuses. There are many modulation strategies for the 3L-NPC inverter, among them, the selective harmonic elimination pulse width modulation (SHEPWM) and selective harmonic mitigation pulse width modulation (SHMPWM) techniques are very useful technologies since they have the characteristics of selective harmonics reduction or elimination. In this paper, simulation models of the 3L-NPC inverter with 10kV grid based on total harmonic distortion (THD) using the SHEPWM and SHMPWM techniques are built in MATLAB/SIMULINK. Here, both the SHEPWM and SHMPWM techniques use fifteen switching angles to generate the switching pattern and the solutions of the nonlinear transcendental equations for these two kinds of PWM techniques are obtained by using the fmincon function with THD-based objective function in MATLAB. Finally, the comparative analysis of the SHEPWM and SHMPWM techniques for the 3L-NPC inverter with 10kV grid based on the THD of voltage and current up to the 50th and the 100th is proposed to verify the respective advantages of the SHEPWM and SHMPWM techniques in different harmonic suppression cases.

This paper presents the mathematical and harmonic analyses of output phase voltages of three-phase voltage source inverters which employ a hybrid two-dimensional-three-dimensional (2-D-3-D) space vector modulation (SVM) voltage control algorithm. The explicit time-domain representation of the harmonic components in addition to the total harmonic distortion (THD) of the output phase voltages is given in terms of system and control parameters. This paper also investigates the harmonic characteristics and THD performance against the linearity of the modulation region which helps in the harmonic performance and design studies of such inverters employing the hybrid 2-D-3-D SVM. The fundamental component of the output voltages follows the reference with lower THD in the linear modulation region rather than the overmodulation region. Experimental results are used to validate these analyses as well as the effectiveness of the hybrid 2-D-3-D SVM algorithm for generating balanced and low THD phase voltages.

A load current observer based feedforward control scheme for three-phase voltage source pulse width modulation (PWM) active rectifiers is presented. The observer is designed to identify the load current disturbance, which is then forwarded to an inner current controller. Details of the design of the inner current controller and outer dc voltage regulator are also presented. To cope with the delay time of the digital control loop, Smith-predictor is employed in the current control loop to stop overshoots and oscillations during transient current regulation. Simulation model has been set up using commercially available VisSim software and then implemented in a digitally controlled prototype of a three-phase PWM active rectifier. The simulation and experimental results show that without using an actual load current sensor, the proposed observer based feedforward control scheme provides almost the same performance as the traditional feedforward control based on actual load current measurement.