Synchronous current control scheme with reference voltage estimation for voltage-fed PWM inverter

A new current control scheme with the reference voltage estimation for a voltage-fed pulsewidth modulated (PWM) inverter is presented. This scheme is simple and can provide smaller current error than predictive control with the same switching frequency when the load parameters are mismatched.<>     

Deadbeat control of PWM inverter with modified pulse patterns foruninterruptible power supply

A modified algorithm of pulse-width-modulation (PWM) inverter deadbeat control suitable for uninterruptible-power-supply (UPS) systems is presented. Two state variables are measured at each sampling interval, then, using the data, the pulse width is computed in real time in order to force the output voltage equal to the reference at each sampling instant which is called the deadbeat control. Two kinds of PWM pulse patterns are used to increase the fundamental component of the output voltage, considering the microprocessor computation time. Experimentation and simulation has verified that the proposed control scheme increased the output-voltage amplitude, providing an excellent transient response and accurate phase positioning for various load conditions. This algorithm is suitable for applications of high-power UPS systems, in which the switching frequency is in the range of a few kHz and the precise control of power flow is required     

Two-level switching pattern deadbeat DSP controlled PWM inverter

A two-level switching algorithm of the deadbeat controlled PWM inverter is presented. Two levels, instead of three levels, are used in the pulse pattern. This scheme allows the use of higher switching frequency for a given computation time delay, which results in lower total harmonic distortion (THD) at the output. Control algorithms are derived. The proposed control scheme is implemented using a TI TMS320C14 DSP controlling an inverter to produce a very low THD sinusoidal output voltage. Simulation and experimental results are presented to verify the performance     

An active circuit for cancellation of common-mode voltage generatedby a PWM inverter

This paper proposes an active common-noise canceler (ACC) that is capable of eliminating the common-mode voltage produced by a pulsewidth modulation (PWM) inverter. An emitter follower using complementary transistors and a common-mode transformer are incorporated into the ACC, the design method of which is also presented in detail. Experiments using a prototype ACC, whose design and construction are discussed in this paper, verify its viability and effectiveness in eliminating common-mode voltage in a 3.7 kW induction motor drive using an insulated gate bipolar transistor (IGBT) inverter. Some experimental results show that the ACC makes significant contributions to reducing a ground current and a conducted electromagnetic interference (EMI). In addition, the ACC can prevent an electric shock on a nongrounded motor frame and can suppress motor shaft voltage     

FPGA-based implementation of online selective harmonic elimination PWM for voltage source inverter

This paper presents a field programmable gate array (FPGA)-based real-time selective harmonic elimination pulse width modulation (SHE-PWM) scheme for voltage source inverter (VSI). The proposed algorithm can generate the switching angles in real time through the approximation of the angles trajectories by simple variable coefficients-based polynomial equations. The proposed algorithm is first presented, analysed, and then its accuracy is checked through angle error analysis. Afterwards, an FPGA-based implementation is used and an induction motor drive is experimentally tested to validate the simulation results. Experimental results showed a good agreement with simulation and proved the validity as well as precision of the proposed algorithm. All intended selected harmonics are eliminated and simultaneously the fundamental is controlled. The output voltage and current present an excellent frequency spectrum with low harmonic distortion and power loss values.     

逆变器电压补偿参数离线辨识及其应用研究

在异步电机三相逆变中,当电机低速运行时,因输出电压较低,由死区时间和信号传播延迟造成的电压损失会使输出电流发生明显的畸变。为改善逆变器输出电流波形,需要进行电压补偿。常用的电压补偿方法有电压反馈补偿、电流反馈补偿、死区解耦补偿、自适应死区补偿等,最常用且容易实现的方法就是电流反馈补偿。电流反馈补偿需要知道电流采样通道及开关器件延迟、开关器件压降、死区时间等参数,为避免直接查阅芯片资料造成的参数误差,本文提出了一种逆变器电压补偿参数离线辨识方法,并研究了该方法在电压补偿中的应用。     

A ZVS PWM inverter with active voltage clamping using the reverse recovery energy of the diodes

This paper presents a zero-voltage-switching (ZVS) pulsewidth modulated inverter with active voltage clamping using only a single auxiliary switch. The structure is particularly simple and robust. It is very attractive for single-phase high-power applications. Switching losses are reduced due to implementation of the simple active snubber circuit that provides ZVS conditions for all switches, including the auxiliary one. Its main features are: simple modulation strategy, robustness, low weight and volume, low harmonic distortion of the output current and high efficiency. The principle of operation for steady-state conditions, mathematical analysis and experimental results from a laboratory prototype are presented.     

Deadbeat control of a three-phase inverter with an output LC filter

The discrete-time control of a three-phase inverter with an output LC filter is described based on space vectors. The mathematical model of the inverter-filter system is first obtained by using space vectors to represent three-phase quantities. Deadbeat control laws are derived for no-load and resistive-load cases. Then, a deadbeat control law is obtained for the case when the load draws current of any waveshape from the inverter-filter. It is shown that deadbeat control of output voltage can be achieved in two control steps. The manipulated variable, which is the voltage vector demanded from the inverter, is implemented using the space vector modulation technique. Simulation results for various operating conditions are presented     

Source voltage sensorless estimation scheme for PWM rectifiers under unbalanced conditions

A source voltage sensorless estimation scheme is proposed for a pulsewidth-modulation (PWM) rectifier in unbalanced circumstances. The negative sequence is accompanied by the unbalance among phases, and acts as an ac disturbance to a normal-mode estimator and controller. Hence, without considering voltage unbalance, a PWM rectifier yields a voltage ripple in the dc-link voltage and large reactive currents. With the proposed sensorless scheme, both positive and negative components are estimated separately by using a full- (or reduced-) order estimator. The feasibility of the proposed sensorless scheme is confirmed through computer simulation and experiment.     

A new pulse-width modulation (PWM) scheme for modular structured multilevel voltage source inverter

This work proposes a new switching scheme for a particular multilevel topology, known as the modular structured multilevel inverter (MSMI). The proposed scheme is based on symmetric regular sampled unipolar PWM, with multiple modulating waveforms and a single carrier. Mathematical equations that define the PWM switching instants are derived. These equations are suitable for digital implementation. An experimental five-level MSMI test-rig is built to implement the proposed algorithm. The derived equations are implemented by a low-cost fixed-point microcontroller. Several tests to quantify the performance of the inverter under the proposed modulation scheme are carried out.     

Design and performance of a passive EMI filter for use with a voltage-source PWM inverter having sinusoidal output voltage and zero common-mode voltage

This paper deals with integrating a small-sized passive electromagnetic interference (EMI) filter with a voltage-source pulse-width modulated (PWM) inverter. The purpose of the filter is to eliminate both high-frequency common-mode and normal-mode voltages from the three-phase output voltages of the inverter. A laboratory system consisting of a 5-kVA inverter, a 3.7-kW induction motor, and a specially-designed passive EMI filter was constructed to verify the viability and effectiveness of the filter. As a result, both line-to-line and line-to-neutral output voltages look purely sinusoidal as if the inverter were an ideal three-phase variable-voltage, variable-frequency power supply when viewed from the motor terminals. This results in a complete solution to serious EMI issues related to high-frequency common-mode and normal-mode voltages produced by the PWM inverter.     

Inductor commutation soft-switched PWM inverter driven byfrequency-modulated PWM signal

This paper presents a novel technique using frequency modulation (FM) to improve the efficiency of an inductor commutation soft-switched pulse-width-modulation (PWM) inverter (ICSI). In the ICSI, a circulating current for soft switching always flows through the switches of the inverter, independent of the load and input signal. The circulating current significantly deteriorates the efficiency of ICSI. With the FM technique, the circulating current is effectively suppressed without sensing any current or voltage in the inverter. Efficiencies of ICSI and ICSI with FM (FM ICSI) are analyzed and verified experimentally. As a result, the efficiency of FM ICSI rises about 20%-40% compared with the ICSI     

Wideband chirp parameter estimation in sensor arrays through DPT

An estimation technique for multiple constant amplitude chirp signals is proposed. The estimation of the initial frequencies, frequency rates and direction of arrivals of individual chirp signals is achieved with 1D searches, hence it is computationally attractive. Simulation and comparative results are given to show the effectiveness of the technique     

A current source PWM inverter with actively commutated SCRs

Conventional SCR based current source inverters suffer from poor waveform quality due to six step switching. Pulse width modulated current source inverters typically require gate turn off devices with reverse voltage blocking capability which have limited their application. In this paper, a new pulse width modulated current source inverter topology using one gate turn off switch and six SCRs is presented. The converter uses active commutation to realize pulse width modulation in a conventional SCR based current source inverter. Modulation techniques for the proposed inverter, simulation and experimental results are described in the paper. This topology is suitable for high performance, high power applications     

PWM technique for power MOSFET inverter

A sinusoidal PWM (pulsewidth-modulated) inverter suitable for use with power MOSFETs is described. The output waveforms in the proposed PWM inverter are investigated both theoretically and experimentally. A modulating signal for the three-phase PWM inverter is obtained by adding the harmonic components of integer multiples of three to the three-phase sine waves. By using the proposed modulating signal, the amplitude of the fundamental component is increased about 15% more than that of a conventional sine-wave inverter and the commutation number of the inverter is decreased to two-thirds of a conventional one     

基于单电磁矢量传感器的MUSIC联合参数估计方法

在有电磁波信息链的条件下,飞行器通过单电磁矢量传感器接收来自基站的完全极化电磁波信号,并对该信号进行处理获得电磁波的波达角和极化角.本文提出了一种新的基于电磁矢量传感器的MUSIC极化-空城联合谱估计方法,此方法将极化空域导向矢量分解成矩阵旋转秉积的形式,并将其作进一步的演化成矩阵生成元的形式.最后用仿真验证了算法的有效性.     

Neutral-point-clamped inverter with improved voltage waveform andcontrol range

A hysteresis controller-based PWM method for neutral point clamped (NPC) inverters is proposed. The closed-loop system uses the two-axis components of the transformed line-to-line voltage vectors as the control variables. In its linear control range, the PWM method includes two operating modes, namely, low and high references. At high references' mode, the output voltage is generated by switching among four vectors instead of three to improve the waveform generation. The proposed system has a linear control range 15.5% wider than conventional phase control methods. Furthermore, the control range can be easily expanded beyond the higher linear controllable range up to the square waveforms without suddenly increasing the waveform distortion. Therefore, the fundamental component of the output voltage can be smoothly and continuously controlled from zero up to square waveforms. The control circuit includes a hysteresis controller that is capable of stabilizing the neutral point potential variations within fixed limits during steady and transient states. The control method also offers high performance and fast response. Computer simulations and experimental results on a laboratory-tested motor drive are given to validate the proposed control scheme     

基于电流无差拍控制的单相光伏并网逆变器研究

摘要：在单相光伏逆变并网系统中,传统控制器由于其控制算法简单使其电流响应速度慢,在电流发生变化时容易产生谐波污染电网,不能满足越来越高的电能质量要求。通过对单相光伏并网逆变器模型的研究,采用一种基于电流无差拍的控制方法,推导出其离散传递函数,并对其进行稳定性分析。在降低稳态误差和提高抗干扰能力的同时使得电流的响应速度提高,并且降低了逆变器并网电流的总谐波畸变率。最后通过仿真和实验验证了理论的正确性和控制方法的有效性。     

Power spectra of a PWM inverter with randomized pulse position

Random pulse width modulation in static power converters results in the partial transfer of power from the discrete spectrum of the output voltage to the continuous spectrum, with advantageous effects on the operation of the supplied electromechanical systems. In this paper, a random PWM technique with randomized pulse position for three-phase voltage-controlled inverters is analyzed. Closed-form equations for the discrete and continuous power spectra of the line-to-line and line-to-neutral voltages of the inverter have been derived and confirmed by experiments. Presented theory opens the way to numerical optimization of the voltage spectra of randomly modulated inverters