B4 Inverter Research Articles

Performance Evaluation of the B4 Topology for Implementing Grid-Connected Inverters in Microgrids

The B4 topology is an interesting alternative to the conventional B6 inverter due to its reduced number of parts and lower cost. Although it has been widely used in the past, especially in low-power motor drive applications, its application as a grid-connected inverter is an open area of research. In this regard, this paper analyses the feasibility of the B4 inverter topology for grid-connected applications. A versatile 7 kW inverter prototype, which may be configured as B4 and B6, was built, allowing for a comprehensive evaluation of the performance of both topologies. Through an analytical study and experimental tests, the performance of the B4 and B6 topologies was comparatively evaluated in terms of efficiency, total harmonic distortion of line currents, current unbalance, cost, and mean time between failures. The study was carried out in the context of microgrid systems, highlighting their role in the integration of renewable energy and distributed generation.

An adaptive, observer-based switching method for B4 inverters feeding three-phase induction motors

Abstract A four-switch inverter called the B4 inverter is a reconfigured topology of a B6 inverter, one leg of which is damaged. The four-switch topology provides the overall system with fault-tolerant characteristics. However, this reconfiguration will not only change the system dynamics but also degrade the system performance. For overcoming with these issues, this paper presents an adaptive switching method based on DC-link voltage control. In the proposed method, the selection of active vectors and the calculation of switching times are made according to an adaptive, observer-based algorithm which will reduce DC-link voltage oscillations and adjust unbalanced currents fed to induction machines. In this algorithm, an online, designed observer is utilized so as to estimate the DC amount of the DC-link voltage. Applying this method, we will decrease flux and torque ripples as well as increase the inverter efficiency and performance. The simulation results presented in the MATLAB environment evaluate and validate the performance and effectiveness of this approach.

A new space vector modulation technique for quasi Z-source B4 inverter

A Quasi Z-Source (qZS) network has been utilized in a B4 inverter topology to provide voltage boosting effect by turning on the upper and lower switches simultaneously which is known as zero shoot-through states. However, the design of a qZS B4 inverter is not as straightforward as adding a qZS LC impedance network to the front-end of a B4 inverter. This is because there is no zero vectors available in a B4 inverter topology to insert the shoot through zero states, as in the case of a B6 inverter. This paper proposes a new Space Vector Modulation (SVM) technique for a qZS B4 inverter. Additional zero vectors have been appropriately added and distributed in the proposed SVM to avoid altering the existing volt-sec per switching cycle for the existing active vectors. The voltage vectors switching placement is carefully designed in order to enable the voltage boosting effect for this topology without altering the initial output voltage. In addition, an approach to compensate the DC-link voltage ripple has also been taken into consideration in its initial calculation to achieve balanced output voltage. The performance of the proposed modulation technique is verified using MATLAB/Simulink. It is shown that by using the proposed modulation technique, there is an overall improvement on the line to line output voltage where by it is able to produce balanced output voltages for the three-phase loads with or without boosting effect.

Efficiency Analysis of Vienna Rectifier-Based Grid interface Systems for Low-Power PM WECS

Losses of power semiconductor switching devices used in grid-connected wind energy conversion systems (WECSs) are regarded as one of the main issues to be considered when comparing different types of grid interface systems (GISs). This loss is more highlighted for low-power applications, because it directly affects the reliability and efficiency of the system. Recently, a GIS using Vienna rectifier (VR) as generator-side converter is investigated for a permanent magnet synchronous generator-based WECS. Due to its cost advantage, this reduced switch count rectifier is specifically attractive for low-power applications. In this study, the analytical relations for switching and conduction losses of a VR-based GIS are derived and compared to conventional back-to-back systems. As for the grid-side converter, two types of inverters, conventional six-switch inverter and B4 inverter, are considered and the efficiency of GIS is investigated analytically. In order to derive the loss equations for VR, a new current PWM method is presented explaining the formulas required for its implementation. Finding the relations for switching loss and efficiency, different GISs are compared and the most efficient ones are determined for different ratings. The GISs are also simulated, and their switching power losses for different operating points are shown.

Sensorless Model Predictive Force Control with a Novel Weight Coefficients for 3-Phase 4-Switch Inverter Fed Linear Induction Motor Drives

The sensorless model predictive force control (SMPFC) is a strong method for controlling the drives of three-phase 4(6)-switch inverter linear induction motors. This kind of inverter can be employed for fault tolerant control in order to solve the problem of open/short circuit in 6-switch inverters (B6). This paper proposed a method for the SMPFC of a linear induction motor (LIM) with a 4-switch inverter fed along with DC-link voltage offset suppression. Numerical simulations have been performed on several different LIMs in MATLAB software for determine the weight coefficients of the stator flux and the reduced of the capacitor voltage offset. Then, a relationship has been extracted for determining the weight coefficients of the stator flux and DC-link voltage in the cost function of the SMPFC. Using weight coefficients in the cost function, the B4 inverter voltage vectors under the DC-link capacitor voltage swing were obtained for the exact prediction. The balance among the currents was improved by determining the appropriate value for the weight coefficient of the reduced of the capacitor voltage offset. Simulation results were provided for the validation of the suggested control method.

Power Factor Correction of Four-Switch Three-Phase Inverter-Fed Sensorless Induction Motor Drives with Partial Electrical Free Measurement

In this article, a novel partial electrical free measurement method to improve the power-factor of four-switch three-phase (B4) inverter for sensorless induction motor drives is proposed. This method uses a simple-free of measuring current or voltage for the power factor correction circuit. The proposed controller of the B4 inverter improves the power factor to be closed to a unity with a high power quality performance and with a minimum total harmonic distortion of the supply current. The complete drive system is carried out utilizing Matlab/Simulink. Also, it is executed in real-time using a prototype system composed of a dSPACE DS-1104 digital control board and a laboratory 1.1 kW three-phase squirrel cage induction motor. The simulation and experimental waveforms prove the efficacy of the proposed drive system under various operating conditions. It is found that the proposed drive system has a reduced number of switches and sensors with a minimum cost which suitable for low commercial power applications. Moreover, it enhances noise isolation between power circuit and controller.

Sensorless Control of PMSM by a Four-Switch Inverter with Compensation of Voltage Distortion and Adjustment of Position Estimation Gain

This paper proposes performance improvement schemes for sensorless PMSM control drive using a four-switch three-phase inverter (so-called B4 inverter). In the proposed scheme, the back-EMF estimation-based sensorless control algorithm is used to control the brushless PMSM without position sensors. In order to have stable operation, this paper presents a gain adjustment scheme that compensates the reduction of stable sensorless operation range as long as the rotor speed increases. In B4 topology, the center point of dc-link capacitors is connected to 3-phase load, and it is prone to have the load current distortion. Hence, to mitigate this problem, a distortion compensation scheme by modifying voltage commands using measured dc-link potentials is proposed in this paper. The validity of the proposed method is evaluated by simulations and experiments.

Design and Implementation of a Low Cost Grid-Connected 5 kVA Photovoltaic System with Load Compensation Capability

Design and implementation of a low cost grid-connected 5kVA solar photovoltaic (PV) system is proposed in this paper. Since the inverter is a major component of the PV system, the B4 inverter used in this paper reduces the total cost of the PV system. In order to eliminate the massive transformer, the PV system is connected to the grid through IGBT switches. In addition to injection of active power into the grid, the B4 inverter can compensate reactive power and reduce harmonics of the nonlinear loads. A TMS320F28335 DSP processor is used for effective control of the B4 inverter. Various features of this processor enable the implementation of the necessary control algorithms. As a first step, the PV system is simulated and evaluated in Matlab/Simulink. In the second step, hardware circuits are designed and implemented based on the simulation results. The operation of the PV system has been evaluated under balanced, unbalanced, linear and nonlinear loads which proves its accuracy and efficiency.

Analysis and control of a reduced switch hybrid active power filter

A hybrid B4 active power filter (APF) with reduced switches is proposed in this study, which is composed of a inductance–capacitance (LC) passive filter and a four-switch three-phase inverter (B4 inverter) in series connection. The LC filter is used to supply reactive power, and the active filter is responsible for mitigating the harmonics. Compared with the previous proposed four-switch hybrid APF, it can overcome the drawback of large dc voltage components appearing in the ac capacitors. Basic principles and steady-state analysis of hybrid B4 APF are introduced in detail. A control scheme based on source current detection is presented. Multiple parallel vector resonance controllers are adopted in the current control loop, and the gains of these resonance controllers are optimised by a particle swarm optimisation approach. Experimental results have verified the effectiveness of the proposed hybrid B4 APF.

Design and Implementation of Modified Buck Boost Converter Fed B4 Inverter for Brushless Dc motor Drive using Low Cost DSPIC Controller

The Research deals with the speed control of Brushless DC Motor drive by low cost dsPIC controller and B4 Inverter with new converter design (Four Switch Inverter) rather than conventional inverter (Six Switch Inverter) is proposed. The conventional Six switch Inverter is modified into B4 Inverter in order to reduce the switch leg failure, and Total Harmonic Distortion. This facilitates the operation of voltage source Inverter at fundamental frequency switching by using the Electronic commutation technique rather than Mechanical commutation. In addition we propose single phase Rectifier and Three phase voltage source Inverter, dsPIC controller to generate the multiple carrier PWM pulses for B4 Inverter which is fed to the Permanent Magnet Brushless DC Motor to obtain the desired motor speed. The proposed Research mainly focused on the new topology of Buck boost converter design for B4 inverter, By this new modified buck boost Enhancement converter design motor speed are controlled and voltage imbalance in the capacitors are avoided the capacitor voltage is similar voltage level is obtained during the buck and the boost mode operation of the converter side, So results with improved quality of Boosted up output DC Power is obtained. Simulation Modeling Results are carried out by Matlab/Simulink environment and Portable Experimental Hardware is developed Results are carried out Sucessfully and Validated for various operating parameter conditions.

Predictive Torque Control Scheme for Three-Phase Four-Switch Inverter-Fed Induction Motor Drives With DC-Link Voltages Offset Suppression

The four-switch three-phase (B4) inverter, having a lower number of switches, was first presented for the possibility of reducing the inverter cost, and it became very attractive as it can be utilized in fault-tolerant control to solve the open/short-circuit fault of the six-switch three-phase (B6) inverter. However, the balance among the phase currents collapses due to the fluctuation of the two dc-link capacitor voltages; therefore, its application is limited. This paper proposes a predictive torque control (PTC) scheme for the B4 inverter-fed induction motor (IM) with the dc-link voltage offset suppression. The voltage vectors of the B4 inverter under the fluctuation of the two dc-link capacitor voltages are derived for precise prediction and control of the torque and stator flux. The three-phase currents are forced to stay balance by directly controlling the stator flux. The voltage offset of the two dc-link capacitors is modeled and controlled in the predictive point of view. A lot of simulation and experimental results are presented to validate the proposed control scheme.

A Simple Current Ripple Reduction Method for B4 Inverters

This paper proposes a simple current compensation method to improve the control performance of B4 inverters. Four-switch inverters so called B4 inverters employ only four switches. They have a split dc-link and one phase of three-phase motors is connected to the center-tap of split dclink capacitors in B4 inverters. The voltage ripples in the center tap of the dc-link generate unbalanced three-phase voltages causing current ripples. To solve this problem, this paper presents a simple compensation method that adjusts switching times considering dc-link voltage ripples. The validity of the proposed method is verified by simulations and experiments carried out with a 1 HP induction machine.

보상전압 첨가를 통한 B4 인버터 성능향상

This paper proposes a current ripple reduction method to improve the control performance of B4 type inverter that is studied for cost-effective drive systems. B4 inverters employ only four switches and they have a center-tapped connection between the split dc-link capacitors and one phase of a three-phase motor or load. In the B4 topology, unbalanced three-phase voltages will be generated due to the dc-link voltage ripple. To solve this problem, this paper presents a voltage distortion compensation method that adjusts the voltage reference with the consideration of dc-link voltage ripple. The validity of the proposed method is verified by simulation and excremental results with an induction machine.

Investigation of the performance of a DTC strategy dedicated to the control of B4 fed induction motor drives

Purpose – This paper seeks to investigate the performance of a DTC strategy dedicated to the control of four‐switch three‐phase (B4) inverter fed induction motor drives. The major advantage of the B4 inverter is the reduced number of the involved power switches which opens up crucial cost benefits.Design/methodology/approach – The principle of operation of the B4 inverter fed induction motor drive is recalled in a first step. Then, the basis of the proposed DTC strategy is presented. Following this, the synthesis of the corresponding vector selection table is carried out considering a subdivision of the space vector plan into sixteen sectors.Findings – It has been found experimentally that the B4 inverter fed induction motor drive offers, under the proposed control strategy, interesting performance.Research limitations/implications – This work should be extended considering a comparison between the performance of B4 inverter fed induction motor drive under the proposed DTC strategy and those of the B6 inv...

Adaptive SVM to compensate DC-link voltage ripple for four-switch three-phase voltage-source inverters

An adaptive space vector modulation (SVM) approach to compensate the DC-link voltage ripple in a B4 inverter is proposed and examined in detail. The theory, design, and performance of this pulsewidth modulation (PWM) method are presented, and the method effectiveness is demonstrated by extensive simulations and experiments. High-quality output currents are guaranteed by this approach even with substantial DC-voltage variations that might be caused by an unbalanced AC supply system, the diode rectification of the line voltages, and circulation of one output phase current through the split capacitor bank. The application of this approach to induction machine drives is also discussed. It is concluded that the DC-voltage ripple effect on the B4 inverter output can be minimized by an adaptive SVM algorithm with the advantage of improving the response of the DC-link filter and the output quality of the inverter becoming high.

A new optimized space-vector modulation strategy for a component-minimized voltage source inverter

This paper presents a new space-vector modulation strategy suitable for a low-cost pulse-width-modulation (PWM) voltage-source (VS) inverter employing only four switches, four diodes, and a split-capacitor bank in the DC link. The work is motivated by the need for an efficient and flexible modulation method, which is optimized with respect to minimum machine-torque ripple. The modulation strategy is named space-vector modulation for four-switch inverter (SVMFSI), and it is realized by planning the switching patterns between four active voltage vectors on the basis of a desired flux trajectory for the stator-flux vector in the AC machine. The strategy is implemented in a single 8-bit microcontroller as a double-sided modulation strategy. Simulations of the machine-torque ripple are performed at a switching frequency of 4 kHz and indicate a torque ripple of 14% at nominal load. Finally, selected results are verified experimentally on a 1.5-kVA prototype B4 inverter. The test results indicate high-quality output-voltage spectra with no low-order voltage harmonics and a harmonic-loss factor (HLF) of 1.12% at unity modulation index.