Input Power Factor Control Research Articles

A Matrix-Type Back-to-Back Converter With Single-Arm Current Injection

A matrix-type back-to-back converter (MT-BBC) with single-arm current injection, consisting of a three-phase rectifier with a small film dc-link capacitor and a three-phase inverter, is proposed in this paper. A clamped modulation strategy is applied to the rectifier, which is featured by only one high-frequency switching bridge arm, reduced switching losses, and enhanced input reactive power control range. By controlling and injecting the quasi-third harmonic current into the phase with a high-frequency switching bridge arm of the rectifier, sinusoidal input currents and controllable input power factor are achieved. A carrier modulation strategy with variable carrier is applied to the inverter to compensate for the time-varying six-pulse dc-link voltage. The presented converter inherits the advantages of both the conventional voltage-source back-to-back converter (V-BBC) and the matrix converter (MC) including simple main circuit structure, sinusoidal inputs and outputs, bidirectional power flow capability, potentially high power density, high reliability, high efficiency, and direct ac-ac conversion. Additionally, the input reactive power control range is extended significantly. The effectiveness of the proposed methods is verified by a 6-kW experimental prototype.

A Novel Unidirectional Three-Phase Multilevel Rectifier Composed of Star-Connected Three Single-Phase Topology Based on Five-Level Flying Capacitor DC–DC Converter

A novel unidirectional three-phase multilevel rectifier composed of star-connected three single-phase topology based on five-level flying capacitor DC-DC converter is proposed, which can be widely applied to many industrial applications, especially for the front-end of multilevel converters for AC adjustable motor drives with open-end winding connection. In addition to not requiring transformers (either line-frequency or high-frequency), compared to other high voltage rectifiers, this proposed topology features fewer active switches with lower voltage stress, a high voltage common DC bus, high input power factor and low input current harmonics. In this paper, a comprehensive analysis to the basic operating principles including the topology configuration, the steady-state modeling and phase-shifted SPWM modulation are presented. A hybrid control strategy is studied, including the input power factor control, the dc-link voltage balancing control and the flying capacitor voltage balancing control with balanced and unbalanced loads. Finally, the experimental results are presented to validate the feasibility and correctness of the proposed solution.

Practical Implementation of the Indirect Control to the Direct 3 × 5 Matrix Converter Using DSP and Low-Cost FPGA

The popularity of multiphase drives is increasing due to the growing interest in drives with more than three phases. One promising topology is the multiphase matrix converters, which enable the implementation of a single-stage AC/AC power conversion system with bidirectional power flow capability. In this paper, we present the implementation of indirect control for a practical sample of the direct matrix converter. To reduce the overall cost of the control solution for these types of converters, we utilized low-cost FPGA and DSP. The usage of only DSP itself was not possible due to low number of available PWM output needed for 3 × 5 MxC driving. Another reason is commutation, which must be precise and fast to avoid any hazardous states in the converter. Due to these problems, the authors decided to implement an algorithm of a combination of DSP and FPGA, where FPGA is used for time critical operations. The indirect algorithm treats the converter as two separate parts, the rectifier and the inverter, with the DC-LINK being fictitious. The matrix converter is composed of compact modules, and the entire system is verified. The practical verification demonstrates that matrix converters can produce a wide range of output frequencies and achieve input power factor control. Finally, we compare and review the practical model with the simulation model, examining efficiency and other parameters.

Three-Level Indirect Matrix Converter With Neutral-Point Potential Balance Scheme for Adjustable Speed Drives

To improve the performance and explore a new solution of adjustable speed drive systems, a T-type three-level indirect matrix converter (T3LIMC) topology and its modulation scheme are presented in this article. The presented topology is composed of an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> input filter, a current-source rectifier, and a T-type three-level inverter, where the split dc source voltage of the inverter is formed by two input line-line voltages and the neutral-point voltage. A multicarrier-based modulation scheme for the inverter and a specific zero-sequence voltage are also developed, and the desired neutral-point current of the inverter is constructed to compensate for the input currents. Consequently, the balanced neutral-point potential and symmetric sinusoidal input currents are achieved without additional control effort. In addition to advantages such as bidirectional power flow, sinusoidal input–output currents, controllable input power factor, no dc-link energy storage elements, and compact structure, the T3LIMC also improves the output waveform quality by generating the three-level output voltages. Meanwhile, the zero current switching (ZCS) operation of the rectifier helps to improve efficiency. Finally, the functionality and effectiveness of the presented topology and modulation scheme are verified by experimental results.

Power Electronics Intelligence at the Network Edge (PINE)—An Approach to Interface PV and Battery Energy Storage Systems at the Grid Edge

In this article, a self-organizing power electronic converter with control intelligence at the edge of the distribution network is proposed. The proposed converter is called power electronics intelligence at the network edge (PINE), and it has the potential to add intelligence at the network edge to the electricity delivery system of the present and in the future. The proposed approach consists of a power electronic converter (rectifier/dc-link/inverter) termed PINE to supply residential loads. The rooftop solar and battery energy storage system is connected to the dc link. With the bidirectional characteristic of the PINE, the load voltage is regulated via feedback, whereas input distribution voltage can be allowed to vary in a range. This type of configuration allows for control of input power factor to be unity and reactive power to be injected at the grid edge to regulate the voltage and also enable energy budgeting, i.e., limit the amount of power to the residential load under disaster situations. With the PINE converter at the distribution edge that can communicate with other PINEs as well as to the distribution system operator, intelligence at the distribution edge can be established. Such a system has many advantages that are discussed in this article. Furthermore, the impacts of increased penetration levels of PINE are shown using a test feeder based on the IEEE-37 test node feeder. Simulation and experimental results on a laboratory prototype system validate the PINE converter concept.

An Active Power Factor Corrected Power Supply fed Induction Motor Drive by Controlling the Leakage Inductance for Transformer with Soft Switching Strategy

Nowadays the use of electronic equipment finds a progressive development in the modern world. Hence it becomes a mandate to check whether the harmonic content of line current of any electronic device which is connected to the ac supply meets the appropriate standards. This demand is satisfied by implementing the Power Factor Correction (PFC) circuit in order to make the input current to be in sinusoidal in nature and in-phase with the input voltage. Numerous solutions are available to make the line current almost sinusoidal. This paper describes an isolated power factor corrected power supply that utilizes the leakage inductance of the isolation transformer to provide boost inductor functionality. The bulk capacitor is in the isolated part of the power supply allowing for controlled startup without dedicated surge limiting components. A control method based on switch timing and input/output voltage measurements is developed to jointly achieve voltage regulation and input power factor control.

An Improved Power Factor Correction with Control of Leakage Inductance

Nowadays the use of electronic equipment finds a progressive development in the modern world. Hence it becomes a mandate to check whether the harmonic content of line current of any electronic device which is connected to the ac supply meets the appropriate standards. This demand is satisfied by implementing the Power Factor Correction (PFC) circuit in order to make the input current to be in sinusoidal in nature and in-phase with the input voltage. Numerous solutions are available to make the line current almost sinusoidal. This paper describes an isolated power factor corrected power supply that utilizes the leakage inductance of the isolation transformer to provide boost inductor functionality. The bulk capacitor is in the isolated part of the power supply allowing for controlled startup without dedicated surge limiting components. A control method based on switch timing and input/output voltage measurements is developed to jointly achieve voltage regulation and input power factor control.

Improvised multi‐objective model predictive control of matrix converter using fuzzy logic and space vectors for switching decisions

Finite control set model predictive control (FCS-MPC) has lately received noteworthy attention in the control of power converters. Such converters have a finite number of switching states, which ensure a small sample space of predictions and minimum computational burden. Although unanimously popular in most converters, multi-objective FCS-MPC (Mo-FCS-MPC) is a particularly attractive choice in the control of matrix converters (MCs), as it enables attainment of multiple objectives with relative ease. Conventionally, a weighing factor-based approach is undertaken in the implementation of Mo-FCS-MPC wherein a cost-function is framed such that each of its constituent objectives, is assigned a relative weight according to its significance. However, the tuning of weights is empirical in nature and hence tedious. This study proposes an improvised technique for implementing Mo-FCS-MPC in MCs while simultaneously meeting a number of objectives such as load current, source current, and input power factor control. Sector information from space vectors of reference output voltages and reference input currents, coupled with a fuzzy decision-making criterion is used to make the final switching decision, hence eliminating the conventional weighing factor-based approach. The inclusion of space vector modulation into predictive control enhances the quality of both loads as well as source current waveforms.

Direct Power-Based Three-Phase Matrix Rectifier Control with Input Power Factor Adjustment

In a current source rectifier such as a matrix rectifier, input voltage and current cannot be in phase unless an additional input power factor control technique is implemented. This paper proposes such a technique for a matrix rectifier using power-based space vector modulation (SVM). In the proposed method, the modulation index and phase required in order to apply the SVM are calculated based on the active and reactive power of the rectifier for intuitive power factor control. The active power that the rectifier should generate for the regulation of the output inductor current is obtained by the PI (proportional-integral) controller. The reactive power, which is supplied by the rectifier for adjustment of the power factor, is assigned differently depending on the output condition: for the output condition capable of unity power factor, it is set to a negative value of reactive power of the input capacitor, and when the unity power factor is not achievable, it is set with the maximum reactive power the rectifier can generate under the given condition to attain the maximum possible input power factor. It is determined whether the given condition is the light load condition by comparing the absolute value of the reactive power supplied by the input capacitor with the maximum rectifier reactive power that can be produced under the given condition. The SVM based on the active and reactive power of the rectifier in this technique allows the input power factor control to be intuitive and simple. The performance and feasibility of the technique were proved by simulation and experimentation.

An Isolated Power Factor Corrected Power Supply Utilizing the Transformer Leakage Inductance

The widespread use of electronic devices increases the need for compact power factor corrected power supplies. This paper describes an isolated power factor corrected power supply that utilizes the leakage inductance of the isolation transformer to provide boost inductor functionality. The bulk capacitor is in the isolated part of the power supply allowing for controlled startup without dedicated surge limiting components. A control method based on switch timing and input/output voltage measurements is developed to jointly achieve voltage regulation and input power factor control. A prototype design is implemented with detailed measurements and waveforms shown to confirm the desired functionality.

Power Factor Control Method Based on Virtual Capacitors for Three-Phase Matrix Rectifiers

This paper proposes a novel input power factor control method based on a concept of virtual capacitors to provide unity input power factor for three-phase matrix rectifiers. The proposed algorithm introduces, at the input terminal of the matrix rectifier, an imaginary input capacitor generated by modifying a reference vector of the space vector modulation method. The virtual input capacitor, which is fictitiously built in parallel with an input LC filter, successfully compensates for the leading power factor of the LC filter of the matrix rectifier. Thus, the proposed method yields a unity power factor operation despite the presence of the LC filter of the three-phase matrix rectifier. In addition, under a condition when the unity power factor operation cannot be realized, the proposed algorithm adjusts a virtual capacitance to obtain a maximum achievable power factor operation. Because the proposed technique yields the input power factor control by introducing the virtual capacitor and adjusting a reference space vector, the proposed algorithm can be easily incorporated with conventional space vector modulation algorithms for the three-phase matrix rectifiers. Thus, the proposed method can control input power factor without employing proportional–integral controllers used in conventional power factor control methods for the matrix rectifiers, leading to simple control structure and straightforward tuning process for power factor control.

Comparative Analysis of Input Power Factor Control Techniques in Matrix Converters Based on Model Predictive and Space Vector Control Schemes

Model Predictive Control (MPC) with a finite control set and space vector modulation (SVM) are the most common control methods for the matrix converters (MCs). This paper is focused on the input and output currents performance analysis of the matrix converter controlled by SVM and MPC. A closed-loop control of the input current displacement angle is employed in the SVM strategy to provide unity input power factor over a wide range of voltage transfer ratio. For MPC, a discrete-time model of the converter, including the input filter and load, are used to predict the input and output currents for each valid switching state. The MPC, SVM, and power factor controlled SVM (PFC-SVM) methods are analyzed in detail, and their performance in controlling the input power factor, current quality, and transient response are compared through numerical simulations and experimental tests.

Matrix Converter Based Open-End Winding Drives With Common-Mode Elimination: Topologies, Analysis, and Comparison

Matrix converter based open-end winding drives modulated with rotating vectors eliminate the high-frequency common-mode output voltage that could otherwise cause motor failure. Unlike back-to-back converters, no intermediate dc bus capacitor is required—better power density and reliability may, therefore, be achievable. A high voltage transfer ratio and input power factor control capability put these open-end winding drives at a significant advantage over conventional matrix converters. At least three realizations of the matrix converter based open-end drive are possible. This paper compares these three realizations to identify the best topology and presents experimental results validating its capabilities. Filter optimization, loss-optimal vector sequences, and other practical considerations are also discussed. Finally, a comparison with the state-of-the-art back-to-back converters is provided to investigate if the potential improvements are in fact attainable.

Control and applications of direct matrix converters: A review

In recent decades, the matrix converter (MC) has emerged as a promising AC/AC converter that performs the direct AC-to-AC conversion. Because of its attractive features such as compact volume, bidirectional power flow, controllable input power factor and sinusoidal waveforms, there has been an increase in MC related research work. Many control techniques have been proposed to control MCs and many potential applications have been investigated. This paper presents the state-of-the-art review in the recent development of control strategies and applications of MCs, starting with MC fundamentals. Some relevant simulation and experimental results are presented to show the performance of the corresponding controllers in specific applications. A wide range of control techniques and potential application fields are covered. Industrial products and modules are also discussed. Comparisons of different control strategies and different applications are summarized and presented. It is concluded that the MC is a promising converter and more research and industry interest is expected, particularly in AC motor drives and renewable energy microgrids.

Constant Switching Frequency DTC for Matrix Converter Fed Speed Sensorless Induction Motor Drive

The paper presents a constant switching frequency scheme for speed sensorless Direct Torque Control (DTC) of Matrix Converter fed Induction Motor Drive. The use of matrix converter facilitates improved power quality on input as well as motor side, along with Input Power Factor control, besides eliminating the need for heavy passive elements. Moreover, DTC through Space Vector Modulation helps in achieving a fast control over the torque and flux of the motor, with added benefit of constant switching frequency. A constant switching frequency aids in maintaining desired power quality of AC mains current even at low motor speeds, and simplifies input filter design of the matrix converter, as compared to conventional hysteresis based DTC. Further, stator voltage estimation from sensed input voltage, and subsequent stator (and rotor) flux estimation is done. For speed sensorless operation, a Model Reference Adaptive System is used, which emulates the speed dependent rotor flux equations of the induction motor. The error between conventionally estimated rotor flux (reference model) and the rotor flux estimated through the adaptive observer is processed through PI controller to generate the rotor speed estimate.

Dual Three-Phase Indirect Matrix Converter With Carrier-Based PWM Method

This paper proposes an indirect matrix converter (IMC) topology with dual three-phase outputs and its effective carrier-based pulse width modulation (PWM) method. The proposed IMC topology can independently supply ac power for two three-phase loads from a single three-phase ac power source. This converter consists of a rectifier stage used in traditional three-phase IMC and a five-leg inverter. Besides a proposed IMC topology, the carrier-based PWM method suitable for this converter is also introduced. The proposed PWM method is easily implemented by using only one symmetrical triangular carrier signal to generate the PWM signals for a rectifier and five-leg inverter. Proposed IMC topology features the advantages of conventional three-phase IMC, such as sinusoidal input/output current waveforms, controllable input power factor, and simple commutation at the rectifier stage. Analysis, simulation, and experimental results are provided to demonstrate the advantages of the proposed IMC topology with dual three-phase outputs and to validate the effectiveness of the applied modulation strategy.

A static and dynamic model of a space vector modulated matrix-reactance frequency converter

The determination of a converter's passive elements and loadability margin for various load and power grid conditions is of great importance to the proper operation of matrix-reactance frequency converters. The modulation strategy of power switches is very important to the voltage gain and input power factor control. The space vector modulation is the most commonly used algorithm for the control of three-phase power converters. In this paper the average-state space method and the two-frequency d–q transformation are proposed as aids in the process of fast verification of the matrix-reactance frequency converter operation under specific conditions. The experimental verification of the proposed model is also presented.

Elimination of common mode voltage using phase shifted dual source matrix converter with improved modulation index

Purpose – The high-frequency common-mode voltage introduced by power converters, using conventional modulation techniques, results in common-mode current that has the potential to cause physical damage to the shaft and bearings of electric drives as well as unwanted tripping of ground fault relays in motor drives and electrical networks. The paper aims to provide a complete elimination of common mode voltage using a matrix converter (MC) with a new modulation strategy that reduces the size of the power converter system considerably. Further, a new MC topology is proposed to eliminate the common mode voltage with improved voltage transfer ratio (VTR). Design/methodology/approach – The direct MC topology is selected, as it is the only converter topology that has the potential to eliminate common mode voltage in direct AC to AC systems. Using the rotating space vector technique, common mode voltage is eliminated but this reduces the VTR of the converter. To improve the VTR, a modified MC topology with a modified rotating space vector strategy is proposed. In addition, for improving the power factor at the input, the input current control strategy is developed. Findings – The use of rotating space vector technique eliminates the common mode voltage even under all input abnormalities like unbalance and harmonics. By applying positive and negative rotating space vectors, input power factor control can be achieved. However, the control range is limited from unity power factor to the output power factor. It is observed that in the current controlled technique the modulation index reduces further. It is also found that there is a reduction in switching stresses of individual switches in proposed topology compared to direct MC topology. Originality/value – In this paper, a modified rotating space vector technique is applied to the proposed converter topology for elimination of common mode voltage with an increased VTR. The topology can be used for common mode voltage elimination in existing electric drives without the need for modifying the drive system.

3상 Z-소스 PWM 정류기의 입력 AC 전압 센서리스 제어

Respect to the input AC voltage and output DC voltage, conventional three-phase PWM rectifier is classified as the voltage type rectifier with boost capability and the current type rectifier voltage with buck capability. Conventional PWM rectifier can not at the same time the boost and buck capability and its bridge is weak in the shoot-through state. These problems can be solved by Z-source PWM rectifier which has all characteristic of voltage and current type PWM rectifier. By shoot-through duty ratio control, the Z-source PWM rectifier can buck and boost at the same time, also, there is no need to consider the dead time. This paper proposes the input AC voltage sensorless control method of a three-phase Z-source PWM rectifier in order to accomplish the unity input power factor and output DC voltage control. The proposed method is estimated the input AC voltage by using input AC current and output DC voltage, hence, the sensor for the input AC voltage detection is no needed. comparison of the estimated and detected input AC voltage, estimated phase angle of the input voltage, the output DC voltage response for reference value, unity power factor, FFT(Fast Fourier Transform) of the estimated voltage and efficiency are verified by PSIM simulation.

Common-Mode Voltage Reduction Methods for Current-Source Converters in Medium-Voltage Drives

Common-mode voltages (CMVs) can lead to premature failure of the motor insulation system in medium-voltage current-source-fed drives. By analyzing the CMV values at all switching states under different operating conditions of a current-source-inverter (CSI)-based motor drive, this paper first indicates that the CMV peaks are produced by the zero states in most of the cases. The nonzero-state (NZS) modulation techniques employed in voltage-source converters are adapted for use in a space-vector-modulated current-source converter (CSC) to reduce the CMV magnitude. For NZS modulation in CSCs, the nearest three-state (NTS) modulation sequences are designed with good low-order harmonic performances in their linear modulation region of ma ≥ 0.67 and with no increase in the device switching frequency. A combined active-zero-state (AZS) modulation technique is also proposed as compensation, for a lower modulation index in the range of 0.4-0.67, when a compromise is made between the dc-link current minimization and high input power factor control. The simulation and experimental results are provided to validate the CMV reduction effects and harmonic performances of the NTS and combined AZS modulation methods in CSI-fed drives.