Some system design considerations for a high switching frequency PWM inverter

A sinusoidal PWM inverter is required to faithfully reproduce the control waveforms at the output with minimum distortion. This paper presents some design considerations for such an inverter. The choice of switching frequency is the main criterion which affects the output voltage harmonic distortion at high switching frequencies. This paper shows that there exists an optimum switching frequency above which the output harmonic distortion becomes more visible. The dead time generator circuit for a low cost inverter and effect of driver circuits on the output waveform are discussed. Experimental results from laboratory models are presented.     

Optimal PWM design for high power three-level inverter throughcomparative studies

Comparative studies between harmonic elimination and optimal PWM strategies are given for high power three-level inverter feeding an induction motor. An effective PWM map construction method based on the valid region on the frequency modulation index plane is suggested. Thereby, an optimal map including asynchronous space vector PWM, harmonic elimination and optimal PWM method is generated covering all of the low, middle and high modulation index regions. The PWM map was designed for 1 MVA rated general purpose GTO inverter and implemented with a digital signal processor. Experimental results are presented for 10 kVA prototype     

基于TMS320F28234的SVPWM等效方法在逆变系统中的应用

基于两电平情况下,分析SVPWM与载波PWM之间的相互关系,得出SVPWM的基于载波PWM的统一实现方法,给出算法流程图并进行仿真。最后通过基于DSP（TMS320F28234）的逆变电路分别进行开环逆变实验和有源逆变闭环实验。结果证明了该等效方法在逆变系统中的应用是切实可行的。     

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     

PWM逆变器消谐方法及仿真研究

本文提出了多电平PWM逆变器抑制谐波的新方法,介绍了H桥级联式（CHB）逆变器的梯形调制法。并通过电力电子仿真实验软件PSIM 6.0,进行仿真实验,验证了同伦算法在SHE-PWM方程组求解中的傅立叶级数运算的推理结果,最终得出了同伦算法在用于非线性数学分析中,具有比牛顿迭代法更高的收敛速度和更广范围的收敛性的结论。     

Zero-phase odd-harmonic repetitive controller for a single-phase PWM inverter

In this paper, a zero-phase odd-harmonic repetitive control scheme is proposed for pulse-width modulation inverters. The proposed repetitive controller combines an odd-harmonic periodic generator with a noncasual zero-phase compensation filter. It occupies less data memory than a conventional repetitive controller does. Moreover, it offers faster convergence of the tracking error, and yields very low total harmonics distortion (THD) and low tracking error. Analysis and design of the proposed system are presented. Experimental results with the proposed repetitive controller are presented to validate the approach. The phenomena of even-harmonic residues in the proposed control system is discussed and experimentally demonstrated.     

A digital control technique for a single-phase PWM inverter

This paper describes the closed-loop control of a single-phase pulsewidth modulated (PWM) inverter using the generalized predictive control (GPC) algorithm. This approach determines the desired switching signals by minimizing a cost function that reduces the tracking error and the control signals. Experimental results have demonstrated that the prototype system performs well     

Performance analysis of a PWM inverter VAr compensator

The performance of a three-phase solid-state reactive power compensator with fast dynamic response is analyzed. The compensator consists of a three-phase pulse-width modulated voltage-source inverter connected to a self-controlled DC bus. The principal advantage of this scheme is that it can maintain a near-unity source power factor without sensing and computation of the associated reactive power component. A mathematical model for the compensator connected across a variable power factor load is derived. The frequency response is obtained for open-loop operation. This allows the design of the controller. Predicted results are verified experimentally for both open and closed-loop responses     

A robust hysteresis current-controlled PWM inverter for linear PMSMdriven magnetic suspended positioning system

Hysteresis current-controlled pulsewidth modulation (PWM) is very robust but it possesses nonconstant switching frequency, and it is difficult to use for high-performance position servo applications. This paper presents a robust hysteresis current-controlled PWM scheme for a magnetic suspended positioning system driven by an inverter-fed linear permanent-magnet synchronous motor having improved performance in these two areas. In the proposed control scheme, the conventional hysteresis PWM mechanism is augmented by a robust harmonic spectrum-shaping controller. The error signal, which represents the switching frequency deviated from the set one, is detected using a notching filter inverse model. Then, the current command is adjusted by a robust compensation signal. The hysteresis band can be equivalently varied to let the dominant harmonic frequency of inverter output be constant, wherein the frequency can easily be changed by tuning the center frequency of the notch filter. The gating signal of switches is not needed to be sensed for making the proposed control. The constant-frequency control performance yielded by the proposed controller is rather insensitive to the system disturbances and the neutral voltage variation due to isolated Y connection. Through applying the proposed PWM inverter, satisfactory position control requirements can be achieved by properly setting the dominant harmonic frequency according to the electromechanical model of the positioning system     

Linear feedback system design

Via fractional representation methods, this paper tries to clarify the role of various conditions used in the feedback system design and stability with respect to the well-posedness of the system, the existence of a solution for stability and design, and the parameterization of the set of complete solutions. The design criterion for stable feedback system design can be used for filters design, as shown in Section 5. Systems to be considered in this paper include the linear time-varying case and results can easily be extended to the case where systems do not have the same number of inputs and outputs.     

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     

An adaptive hysteresis-band current control technique of avoltage-fed PWM inverter for machine drive system

An adaptive hysteresis-band control method where the band is modulated with the system parameters to maintain the modulation frequency to be nearly constant is described. Although the technique is applicable to general AC motor drives and other types of load, an interior permanent magnet (IPM) synchronous machine load is considered. Systematic analytical expressions of the hysteresis band are derived as functions of system parameters. An IPM machine drive system with a voltage-fed current-controlled PWM (pulse width modulation) inverter has been computer simulated to study the performance of the proposed method     

Switching frequency optimal PWM control of a three-level inverter

A pulse-width-modulation (PWM) method for the control of a three-level inverter is described. The switching frequency optimal-PWM method (SFO-PWM) works with a constant carrier frequency not synchronized with fundamental stator frequency. SFO-PWM gives an optimal utilization of the mean thyristor switching frequency permitted; therefore, PWM carrier frequency may be chosen to a value of two times the permitted mean thyristor switching frequency. The signal processing structure is simple. Many applications of three-level inverter work with a DC-link neutral point not stabilized from the power input converter. A neutral-point potential control is described, which is capable of stabilizing potential by varying the switching sequences of the three-level inverter itself. Results from computer simulation and practical experience show the good performance of SFO-PWM     

Failures-tolerance and remedial strategies of a PWM multicell inverter

The aim of this paper is to explain the intrinsic short-circuit tolerance of an IGBT multicell inverter when a commutation failure occurs. Such a failure may either be a wrong gate voltage (malfunctioning of the driver board, auxiliary power supply failure, dv/dt disturbance) or an intrinsic IGBT failure (over-voltage/avalanche stress, temperature overshoot). IGBT stresses are studied and show that no opening of the bonding can appear and consequently no risk of explosion. That is why, owing to the imbricated cells structure, an IGBT short-circuit failure may be withstood for a few switching periods, with nevertheless nonoptimized output waveforms. The design, the lab-test of a sensor able to perform monitoring as well as the failure diagnosis are also presented. This real-time diagnosis allows either a safe stop or a remedial control strategy based on the reconfiguration of the PWM modulator. The reconfiguration strategy enables decrease of internal stresses and optimization of the output shape. A fail-safe operating may be gained for high power applications.     

Secondary control for a series reactive compensator based on a voltage-source PWM inverter

This work describes a secondary control scheme of a series reactive compensator for a power system based on a single voltage-source pulse-width-modulated (PWM) inverter. The controllable capacitive reactance can be used as a supplementary control variable for the secondary (external) controller (SC) of a series capacitive reactance compensator to improve the dynamic transient and damping performances of the power system. From the viewpoint of agent-based global dynamic optimization of a system, the selection and use of suitable input signals for the SC are investigated. Detailed simulation results show that the SC with local feedback loop (LFL) has a powerful control performance; however, it requires the controllable compensation for a reference change due to different operating conditions. On the other hand, the SC with global feedback loop (GFL) avoids the need of reference compensation; moreover, its dynamic control performance is improved when the dual inputs (frequency and active power signal) are used, compared to when only the frequency is used as an input signal.     

Effects on commutation elements in inductor commutationsoft-switched PWM inverter and its design equations

The inductor commutation soft-switched PWM inverter (ICSI) and ICSI driven by frequency modulated PWM signal (FM-ICSI) are analyzed, considering the effects on the commutation elements for the soft switching. From the analysis, the design equations for the commutation elements is clarified and these are verified experimentally     

A simple and accurate method of computing average and RMS currentsin a three-phase PWM inverter

The design of three-phase pulse-width-modulated (PWM) inverters requires values for the average and RMS currents in the inverter in order to select the right components. A computer-aided investigation of approximate inverter current waveforms indicates that the average and RMS inverter currents are simple functions of a single factor equal to the product of the power factor and the modulation index. These functions are expressed as per-unit equations that are useful not only for designing new inverters, but also for evaluating existing designs     

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     

Zero tracking error controller for three-phase CVCF PWM inverter

A zero tracking error control scheme for three-phase CVCF PWM inverters is proposed. The proposed scheme uses repetitive controller (RC) to force output line voltages to track a sinusoidal reference signal with zero error. Minimised voltage distortion and a fast response are obtained. The validity of the proposed scheme has been verified by simulations