Input Phase Voltage Research Articles

Reconstructed Phase Voltages Based Power Following Control for Three-Phase Buck Rectifier Under Unbalanced Phase Voltages and Wide AC Input Frequency

In wide ac input frequency applications, such as more electric aircraft, ac input frequency of the three-phase buck rectifier varies in the range of 360–800 Hz. In this article, a reconstructed phase voltages based power following control for the three-phase buck rectifier under unbalanced input phase voltages in wide ac input frequency application is proposed. The input phase voltages are reconstructed to get more balanced modulation signals compared with the input phase voltages. The input currents are controlled to be in proportion to the reconstructed phase voltages to mitigate the imbalance of the input currents. The control strategy is simple and easy to be realized in digital. The analysis and design of the proposed control strategy and digital implementation are illustrated. An experimental prototype with 1.5 kW is built. The experimental results show that the sinusoidal input currents can be obtained when input phase voltages are unbalanced in wide ac input frequency application.

A DPWM Modulation Strategy to Reduce Common-Mode Voltage for Indirect Matrix Converters Based on Active-Current Vector Amplitude Characteristics

Based on the characteristics that the amplitude of active-current vector in the rectifier stage is zero when the zero-voltage vector is used in the inverter stage, and any one from the six active-current vectors can be selected, a novel discontinuous pulsewidth modulation (DPWM) strategy for the indirect matrix converter is proposed in this article to reduce the common-mode voltage (CMV). In this DPWM strategy, the reference current vector in the rectifier stage is synthesized by two adjacent active-current vectors, and the reference voltage vector in the inverter stage is synthesized by two adjacent active-voltage vectors and one zero-voltage vector. When zero-voltage vectors are used in the inverter stage, an appropriate active-current vector with the lowest input phase voltage among the two adjacent active-current vectors is used to produce a lower CMV. Under the same switching loss, the proposed strategy has a better input performance and better output performance in high voltage transfer ratio than conventional SVM. Finally, the effectiveness of the modulation strategy is verified by simulation and experiments.

Design of an AC Voltage Regulator Using a Harmonic Free TCR

In this work, a T-connected phase voltage-controlling scheme is presented. The mid branch of the T-configuration is a pure susceptance controlled smoothly in inductive and capacitive operating modes. This susceptance is built of a TCR shunted by a filtering circuit, which is designed to suppress the three significant odd harmonics released by the TCR. The left hand branch is a pure inductive impedance, while the right hand one is a pure capacitive impedance equal in magnitude to the left hand one. If the input phase voltage is below its rated value VLrated, then the controlling susceptance is capacitive and its value is set such that it can raise the load voltage to its desired rated value. If the input voltage is above its rated value, then the susceptance is inductive causing the load voltage reduce to its desired rated value. The regulator is harmonic free and capable of keeping its output voltage within its rated value even though its input voltage is varying in the range of (0.75-1.25)VLrated. Once a voltage disturbance occurs, the regulator approaches its steady state response within five cycles of the input phase voltage. The regulator is capable of supplying 220 V, 50 Hz, 3 kVA loads.

Three-phase Active Tracking AC-AC Voltage Regulator based on Buck Converter with an Efficient Hybrid Control Technique

This study proposes a switch-mode three-phase active tracking AC-AC voltage regulator based on the buck converter. The regulator topology incorporates a moderate number of components with less complexity and high efficiency. An efficient hybrid control technique, based on a closed-loop PID controller that is supported with a new designed feedforward controller, is proposed for the regulator control different to the similar studies in the literature. The hybrid control technique augments the response of active tracking of the reference output phase voltages to achieve an improved quality close to sine-wave output phase voltages for either the input AC phase voltages that are ideal pure sine-wave or include various harmonics. The regulator topology has a modular structure for independent control of each output phase. So, the regulator can help to achieve close to sine-wave output phase voltages to supply a balanced/unbalanced wye-connected three-phase load or independent single-phase loads. The presented three-phase regulator and the control technique are tested with simulation and experimental studies. The laboratory set-up of the regulator is designed for 2.2 kW output power, 0-300 Vp input phase voltages (50 Hz), and 0-200 Vp output phase voltages. The results demonstrated that the proposed switch-mode three-phase buck-type active tracking voltage regulator can provide the desired AC phase voltages with less than 5% THD (total harmonic distortion) and low harmonics for different operating conditions.

Boost Converter Based 3-phase AC-AC Active Tracking Voltage Regulator Controlled by a Robust Hybrid Control Method

In this study, a switch-mode three-phase active tracking AC-AC voltage regulator based on the boost converter is proposed with a moderate number of active and passive elements used in the topology. A robust hybrid control, where a novel designed feedforward controller supports the closed-loop PID controller, is proposed for the control of the regulator apart from similar studies in the literature. Active tracking response of the reference output phase voltages is augmented by the proposed hybrid control method. Thus nearly close to sine-wave output phase voltages can be obtained, whether the input AC phase voltages are ideal pure sine or not. Also, the modular structure of the regulator topology enables independent control for each output phase. Thus, the supply of balanced/unbalanced wye-connected three-phase loads or independent single-phase loads with nearly close to ideal sine wave voltages can be achieved by the modularity of the regulator. Both experimental and simulation test studies are performed for the proposed regulator system. A laboratory set-up for the regulator is designed for 0-200 Vp input phase voltages (50 Hz), and 0-300 Vp output phase voltages, and 1.8 kW output power. The achieved results for both simulation and experimental tests verify the proposed switch-mode boost-type regulator’s ability to provide output phase voltages nearly close to sine wave with total harmonic distortion (THD) values under 5%.

Space-vector modulation for three-phase indirect matrix converters to reduce common-mode voltage

This paper presents a space vector modulation strategy for a three-phase indirect matrix converter to reduce the common-mode voltage and maintain the output performance. To reduce the peak value of the common-mode voltage to 57.7% of the input phase voltage, three active voltage vectors are used to generate the desired output voltage with arbitrary amplitude and frequency, instead of using both active and zero voltage vectors as in the traditional space vector modulation strategy. Although the common-mode voltage is reduced, the output waveform quality of the three-phase indirect matrix converter deteriorates due to the absence of the zero voltage vectors. To overcome this problem, the proposed space vector modulation strategy is redesigned to control the rectifier stage of the indirect matrix converter by utilizing three active current vectors instead of two as usual. Consequently, the constant average dc-link voltage is achieved, which can improve the output performance in terms of the output voltage and current harmonic distortion. The simulation is implemented by PSIM software and experimental results are provided to verify the effectiveness of the proposed space vector modulation strategy.

Exploring the Theoretical Limit of Voltage Transfer Ratio of Matrix Converter Under the Constraint of Rotating Vector

The rotating vectors of a matrix converter are uniquely featured by producing zero common-mode voltage, and control methods using them have the advantage of inherently achieving common-mode voltage minimization. However, the existing knowledge of their low voltage transfer ratio (VTR) has made it difficult for rotating vectors to get practical applications. This paper derives the theoretical limit of the VTR under the constraint of rotating vector. Firstly, the principle of selecting the voltage vector for maximum VTR is analyzed. Then the range of matrix converter input voltage phase angle is divided into intervals, and the phase angle of the selected rotating vector within each interval is determined. Finally, through integral and average calculations, the maximum VTR, 9/ $\pi ^{2}$ , is obtained, which is more than 80% higher than that of the linear modulation limit. Simulation and experiments are carried out to verify the correctness of the conclusion.

An Improved Three-Phase Buck Rectifier With Low Voltage Stress on Switching Devices

An improved three-phase buck rectifier (3ph-BR) with low voltage stress on switching devices is proposed in this letter. In the conventional 3ph-BR, the voltage stress on MOSFET s is higher than the amplitude of input phase voltage. However, in the proposed 3ph-BR, the voltage stress on MOSFET s is lower than the amplitude of input phase voltage, which results in reduction of voltage stress on MOSFET s. Therefore, the cost-efficient and low voltage rating MOSFET s with low on-resistance can be utilized, which makes the proposed 3ph-BR suitable for applications that require high-efficiency and high-density. A 1.5-kW experimental prototype of the proposed rectifier is built to verify the analysis results.

Analytical Calculation of Performance of Line-Start Permanent-Magnet Synchronous Motors Based on Multidamping-Circuit Model

This article presents a new analytical method for calculating performance of line-start permanent-magnet synchronous motor (LSPMSM) based on multidamping-circuit model (MDCM) to take spatial harmonic components of LSPMSM into account. First, MDCM of damping bar in the rotor is established according to Kirchhoff's current law. Second, an eleven-order system of LSPMSM is deduced from a group of differential equations according to the equations of flux linkage, voltage, torque, and motion. Then, starting process of LSPMSM is simulated with the proposed analytical method, including speed, current, and electromagnetic torque waveforms versus time, respectively. The starting performance and synchronization capability are analyzed and compared under different effective value of input phase voltage, moment of inertia, and load torque. The simulation time with finite element method is about 1235 times longer than the simulation time with the proposed analytical method to calculate the starting process of LSPMSM with the same computer. Finally, the validation of the developed analytical method based on MDCM is verified by comparing simulating results with experimental results and direct axis and quadrature axis (DQ) model. The results based on this new method are reliable. It is conducive to calculate, analyze, and design LSPMSM with less time.

Research on power supply of booster based on PWM rectifier

The magnet power supply system of HEPS mainly includes the linear magnet power supply, the booster power supply, the transportation line magnet power supply and the storage ring magnet power supply. According to the physical design requirements, the output current of the booster magnet power supply is a current with a DC bias period of 1 Hz, and the waveform can be a sine wave or a trapezoidal wave (Jiang et al. Sci Sin Phys Mech Astron 44(10):1075–1094, 2014). The dipole magnet of the booster should be powered in series, the inductance value is relatively large (about 160 mH), and the power of the power supply reaches several hundred kilowatts. The three-phase PWM rectifier controls the orderly turn-on of power electronic devices and takes the input voltage phase of the power grid as the command current phase to make the input current waveform follow the power grid voltage, so as to achieve the purpose of improving the power factor. In this paper, the PWM rectifier is modeled and simulated, and based on the simulation, an experimental prototype is built. The experimental results of the power supply prototype of the PWM rectifier show that the PWM rectifier can achieve high power factor operation on the grid side (Akagi and Sato, in: Control and performance of a flywheel energy storage system based on a doubly-fed induction generator–motor for power conditioning, 1999). The PWM rectifier can be used in the power supply of the booster and has a very good application prospect.

Rotating sector switching table‐based direct torque control of matrix converter‐fed PMSM drives for common‐mode voltage minimisation

A novel direct torque control (DTC) using rotating sector switching table is proposed for a matrix converter (MC) fed permanent magnet synchronous motor (PMSM) system in order to minimise common-mode voltage of the system, exploiting MC rotating vector's advantage of generating zero common-mode voltage. To overcome the difficulty that the angle between adjacent rotating vectors varies according to the phase of input voltage, the rotating vectors are classified into two groups, and each group of vectors have identical rotating direction and fixed angle between adjacent vectors. Rotating sectors of the vector plane are then established, and concise switching table is put forward for the MC-DTC. Experiments are carried out on a 1.6 kW prototype. The results demonstrate considerable common-mode voltage reduction and adequate dynamic performance of the proposed MC-DTC.

Direct Torque Control of Matrix Converter-Fed PMSM Drives Using Multidimensional Switching Table for Common-Mode Voltage Minimization

A novel direct torque control (DTC) is proposed for a matrix converter (MC)-fed permanent magnet synchronous motor (PMSM) drive system in order to minimize common-mode voltage. Rotating vectors are utilized due to the fact that they produce zero common-mode voltage. As the distribution of rotating vectors varies with the input voltage phase, the DTC switching table has to vary for numerous different values of input voltage phase, which will lead to a highly complicated control structure. The merit of the proposed MC-DTC method is that it provides a feasible and fairly simple way to establish a multidimensional switching table for rotating vectors. To fulfill that, six specific values of input voltage phase are selected to approximately represent the whole range of (0, 2π), and the corresponding six switching tables are combined as the multidimensional switching table. Experiments are carried out, and the results show that adequate dynamic and steady-state performance and considerable common-mode voltage reduction are achieved by using the proposed MC-DTC.

Investigation of automatic electric drives balancing transformers with lead control angles

Analysis were carried out of power rectifiers’ commutation in balancing transformers at lead control angles, positive effect of shielding angle against surge voltage on the equipment main performance indicators was established, equations and experimental characteristics of this component operation were provided. As a result of theoretical and experimental investigations of the surge protection device operation, a significant positive effect on the quality of switching power rectifiers in the balancing transformer in case of lead control angles was detected. The relationship between the degree of reduction of overvoltage in the input phase voltage of the converter and the capacitance values of the capacitor, the angle of the first switching stage and the lead control angle of the converter were determined. A further study of the unit operation is to establish practically applicable quantitative relations between the specified values.

Optimal Switching Frequency Variation Range Control for Critical Conduction Mode Boost Power Factor Correction Converter

Critical conduction mode boost power factor (PF) correction converter is widely used in low-to-medium power applications for its advantages of high PF, zero-current turn-on of the switch, and no reverse recovery in diode. Nevertheless, the switching frequency varies continually with the input voltage phase angle with traditional constant on-time control. This makes the electromagnetic interference (EMI) spectra display great differences and complicates the design of EMI filter. An optimal switching frequency variation range control strategy is proposed in this article. The optimal harmonics amounts for the lowest switching frequency variation range without and with a limited PF are both figured out. In addition, a lower output voltage ripple is obtained. A prototype has been built and tested in the lab to demonstrate the validity of the theoretical analysis.

A Novel Direct Torque Control of Matrix Converter-Fed PMSM Drives Using Dynamic Sector Boundary for Common-Mode Voltage Minimization

In this article, a novel direct torque control (DTC) using dynamic sector boundary is proposed for a matrix converter (MC) fed permanent magnet synchronous motor drive system in order to minimize common-mode voltage (CMV) of the system, based on the fact that rotating vectors produce zero CMV. According to the feature of rotating vectors that their relative position varies with the varying of the phase of input voltage, the vector plane is divided into sectors with dynamic boundaries, and the rotating vectors are redenoted dynamically. A novel switching table and a mapping table of rotating vectors are established according to the control effects of each rotating vector in each sector, and DTC with only rotating vectors is achieved. Experiments with a 2-kW prototype are carried out. The results show that adequate dynamic performance and considerable CMV reduction is achieved by using the novel MC-DTC.

Simplified Space-Vector Modulation Strategy for Indirect Matrix Converter With Common-Mode Voltage and Harmonic Distortion Reduction

This paper presents a simple space vector modulation (SVM) strategy for a three-phase indirect matrix converter (IMC) to reduce common-mode voltage (CMV) and output harmonic distortion. To suppress the CMV peak value to 57.7% of the input phase voltage, three active voltage vectors are used to generate the desired output voltage with arbitrary amplitude and frequency. However, the output waveform quality of the IMC deteriorates due to the absence of zero voltage vectors. To overcome this problem, this paper proposes to redesign control of the rectifier stage by utilizing three active current vectors instead of two, as is common. Consequently, a constant average DC-link voltage is achieved, which can improve the output performance in terms of output voltage and current harmonic distortion. Compared to the existing strategies, the proposed strategy can reduce the CMV and maintain output harmonic distortion without increasing the computation burden. Implementation of the proposed strategy is also straightforward and simple. Simulated and experimental results are provided to verify the effectiveness of the proposed strategy.

Reduction of Common-Mode Voltage in Matrix Convert-Fed Permanent Magnet Synchronous Motor System With Rotating Vectors

A novel direct torque control (DTC) strategy is proposed to reduce common- mode voltage in matrix converter (MC)- fed permanent magnet synchronous motor (PMSM) system, by way of replacing some of the active vectors in the traditional DTC switching table with rotating vectors. According to the variation of the direction distribution of the rotating vector with the input voltage phase angle, the range of input voltage phase angle is divided into two intervals. In one interval, some of the active vectors are replaced by rotating vectors; in the other, all vectors used are rotating vectors. The novel DTC switching table is obtained accordingly. Experimental study verified the effectiveness of the new control strategy. The results show that more than 60% of the common-mode voltage can be suppressed, while the waveform quality of torque and current can be reserved.

An Improved Three-Phase Buck Rectifier Topology With Reduced Voltage Stress on Transistors

The three-phase buck rectifier (3ph-BR) is suitable for applications where a voltage step-down function is required. In this paper, an improved 3ph-BR topology is proposed to reduce the voltage stress on the transistors. The freewheeling diode in the conventional topology is split into two diodes in series and the input neutral point is connected to the common point of the two diodes. With the proposed topology and the corresponding modified modulation scheme, the transistors only need to withstand the input phase voltage instead of the line-to-line voltage, bringing about the significant reduction of voltage stress. The proposed topology enables a more cost-efficient and flexible selection of the transistors. Experimental results have verified the validity of the modified topology and associated modulation scheme.

The novel short circuit withstand test configuration for ITER VS1 power transformer

The ITER (International Thermonuclear Experimental Reactor) Coil power supplies will be installed to provide controlled DC power to the superconducting tokamak magnets for plasma operation. The short circuit withstand test is required to the ITER power supply for safety. Among several ITER coil power supplies, VS1 power supply is to dedicate plasma vertical stabilization (VS). In accordance with IEC standards, the single phase input voltage which is different from the three phase input voltage could be used for the short circuit withstand. To satisfy the electromagnetic force deviation of IEC standard, we propose a novel short circuit withstand test method using the single phase voltage. The short circuit withstand test of VS1 power transformer is successfully performed by the proposed method in the KERI (Korea Electrotechnology Research Institute).

Unbalanced Three-Phase <inline-formula> <tex-math notation="LaTeX">$LLC$</tex-math> </inline-formula> Resonant Converters: Analysis and Trigonometric Current Balancing

Three-phase $LLC$ resonant converters can handle very high power levels beyond the capabilities of half-bridge and full-bridge $LLC$ topologies. Among other characteristics, three-phase $LLC$ structures reduce output current ripple (small output filter), enable parallel power processing (low peak current), and provide good thermal distribution. However, all these key advantages can be severely compromised due to passive components tolerances, leading to undesired current balance issues in three-phase $LLC$ resonant converters. Tolerances in resonant tank passive components are inevitable and lead to unequal peak currents between phases, uneven temperature distribution, and large output current ripple. This paper investigates the imbalances in three-phase $LLC$ converters and proposes a novel trigonometric current balancing (TCB) technique using phasor analysis. In this strategy, the required input voltage phase angles are calculated to achieve balanced phase currents, even under severe unbalanced conditions. In some cases, the output filter current ripple is reduced to less than half. The methodology is verified with a 3-kW experimental prototype, which validates the analytical framework and effectiveness of TCB.