基于空间矢量调制三相电压型PWM整流系统的仿真

正弦脉冲宽度调制(SPWM)技术应用于传统的电压型PWM整流中,SPWM的控制波形可由相间解耦得到。然而,这个过程复杂且直流电压利用率很低。本文提出了一种在同步参考坐标下的三相电压模型的控制策略,空间矢量脉冲宽度调制(SVPWM)。整流器具有高质量的直流侧电压和功率因数。文章提供了MATLAB/SIMULINK的仿真模型。结果证实了模型的正确性及其控制方法。仿真结果表明,与传统的SPWM方法相比,这种方法能明显提高系统的动态性能。     

Voltage harmonics generated by voltage-fed inverters using PWMnatural sampling

The harmonics generated by natural sampled pulse width modulation are investigated experimentally and by theoretical models for the outputs obtained with triangular and sawtooth carrier signals. These equations are valid for synchronous and asynchronous operation. It is shown that triangular carriers generate less harmonics than sawtooth carriers, and that in synchronous operation with single-phase modulation, the carrier-to-output frequency ratio may be any integer value     

Optimal control of three-level PWM inverters

An harmonic loss-minimized optimal PWM strategy for three-level inverters is investigated. The different PWM methods for low-, middle-, and high-speed regions are presented. It is shown that, for three-level inverters, the optimized strategy in all speed regions differs from the optimal PWM strategy of two-level inverters. The developed optimal control ensures a minimum of harmonic losses for a predetermined number of commutations of three-level PWM inverters and for a given value of the fundamental harmonic voltage     

Predictive current control of voltage-source inverters

A new predictive current controller for a voltage-source inverter is presented in this paper. Practical aspects of realizing the new controller in a system with a digital signal processor (DSP) are considered. Delays introduced by measurements are considered and an improved algorithm with one-period prediction of current is presented. The controller was realized in an experimental system with DSP and field-programmable gate array circuits. Results of the simulations and experiments are presented.     

Digital phase control for resonant inverters

This letter presents an approach for direct digital phase control of resonant inverters that is based on inductor current or voltage sensing. Compared to frequency control, phase control provides the advantages of self-tuning to the tank resonant frequency, reduced sensitivity for improved control near resonance, and inherent protection against operation below resonance to avoid hard switching. The digital control algorithm suitable for implementation using standard CMOS logic is derived. The design details of an experimental test platform based on a Xilinx field programmable gate array (FPGA) and experimental results for a typical resonant inverter are provided.     

基于ATmega48的三相无刷电机控制方法

介绍了采用ATmega48单片机实现三相无刷直流电机控制器的方法.利用Atmega48获得带死区的脉宽调制(PWM)、霍尔传感器的换相处理、正弦驱动信号的产生和电机转速的控制等功能.采用该方法的优点是所需的外围器件少,成本低.     

Novel current control method for PWM inverters

A new current control scheme is suggested which is suitable for AC servo drives. The scheme has a simple feedback configuration to determine an optimal stator voltage vector. Minimisation of either current deviations or switching frequency is possible without changing the controller configuration.     

Adaptive control in series load PWM induction heating inverters

Permanent variations of the electric properties of the load in induction heating equipment make difficult to control the plant. To overcome these disadvantages, the authors propose a new approach based on adaptive control methods. For real plants it is enough to present desired performances or start-up variables for the controller, from which the algorithms tune the controllers by itself. To present the advantages of the proposed controllers, comparisons are made to a PI controller tuned through Ziegler–Nichols method.     

A vector control technique for medium-voltage multilevel inverters

This paper presents a switching strategy for multilevel cascade inverters, based on the space-vector theory. The proposed switching strategy generates a voltage vector with very low harmonic distortion and reduced switching frequency. This new control method is an attractive alternative to the classic multilevel pulsewidth modulation techniques considering the following aspects: (1) voltage and current total harmonic distortion; (2) range of linear operation; and (3) number of commutations.     

A voltage control strategy for current-regulated PWM inverters

Alternative voltage control strategies for current-regulated PWM inverters are analyzed, including previously established feedforward and feedforward/feedback controllers and a newly proposed decoupling feedback control strategy. The steady-state and dynamic characteristics of each of these control methods are illustrated and compared for a selected inverter design. It is shown that the feedforward controller exhibits steady-state error and an undesirable overshoot of the output voltages during startup. The addition of a feedback loop eliminates the steady-state error and reduces the overshoot; however, the natural response is underdamped regardless of the choice of feedback gains. A decoupling feedback control strategy that eliminates the disadvantages of the feedforward and feedforward/feedback controllers is described. Using the decoupling feedback controller, it is possible to eliminate the steady-state error and place the closed-loop poles wherever desired. Moreover, if the closed-loop poles are selected appropriately, it is possible to eliminate the overshoot of the output voltages during startup transients     

A digital dual-modulation control for single-phase UPS inverters

A trip-point modulation strategy is proposed for single-phase uninterruptible power supply inverters with an LC filter, which operates simultaneously with pulse-width modulation, named dual-modulation (DM) control. Current estimation and offset current approximation are used conjointly to facilitate the proposed control law. It is shown analytically that the DM control leads to reduced total harmonic distortion (THD) and gains fast transient-state recovery. The simulation and experimental results demonstrate significant amelioration to THD and dynamic state compared to proportional–integral–derivative control under both linear and non-linear loads.     

Asymmetrical voltage-cancellation control for full-bridge series resonant inverters

This paper presents and analyzes the asymmetrical voltage-cancellation (AVC) control, a generalized control technique for resonant inverters. It is applied to the popular full-bridge series resonant inverter. The proposed control technique achieves better efficiency performances than conventional fixed-frequency control strategies, while considering zero-voltage-switching operation, output power and load variations. The theoretical results are verified experimentally, using a prototype for an induction-heating cooking appliance.     

A novel control method to minimize distortion in AC inverters

In pulse-width-modulation (PWM) AC inverters, the duty-cycle modulator transfer function must be highly linear to achieve low distortion. Current-mode (CM) control, inherently nonlinear, is needed to actively “damp” otherwise high-Q LC noise-reduction filters. A novel CM control approach is proposed which tailors external ramp characteristics to achieve “perfect” transfer function linearity-regardless of duty cycle-and guarantee subharmonic stability. Supporting mathematical analysis and prototype measurements are included. The method, when applied to DC/DC power converters, provides fixed gain bandwidth in the continuous conduction mode over a broad line and load range     

Phase compensation second-order repetitive control for CVCF PWM inverters

Phase compensation for high-order repetitive control (HORC) can improve system transient and steady-state performances. The phase compensator is often designed as the inverse transfer function of a closed-loop system. No other phase compensation methods for HORC have been reported up to now. Hence, in this paper, a simple approximate phase cancellation second-order repetitive control (RC) is proposed. The compensator is a linear combination of two different linear phase lead compensators, which can better fit the inverse of a plant model phase curve compared with the conventional linear phase compensator. Optimisation is introduced to design the parameters of the approximate phase cancellation second-order RC. Analysis and design of the second-order repetitive controlled pulse width modulation inverter system are presented. Simulations and experiments are provided to demonstrate the effectiveness of the optimisation method and verify the advantage of the approximate phase cancellation compensator.     

Input current harmonic analysis of pseudo 12-pulse 3-phase to6-phase cycloconverters

A general analytic approach is presented for input current harmonics in a pseudo 12-pulse 3-phase to 6-phase cycloconverter system. The results can be used to predict the existence or absence of a particular frequency component in the input current of such systems under both symmetrical and asymmetrical operating conditions. A quantitative relationship is established to estimate the amplitudes of the harmonics based on the analysis of a typical 6-pulse 3-phase to single-phase cycloconverter     

Efficiency optimization in ZVS series resonant inverters with asymmetrical voltage-cancellation control

This paper presents a time-domain analysis and a computerized search algorithm for optimizing the efficiency in zero-voltage switching (ZVS) full-bridge series resonant inverters with asymmetrical voltage-cancellation (AVC) control for different load quality factors. The optimum AVC control found allows all the switches to be turned on with zero voltage with the minimum switching frequency. In order to minimize losses, the switching frequency is kept as close as possible to resonance. The optimum AVC control is compared with previous fixed or narrow frequency range control strategies to show that it improves performance over all the output power range for different loads. The detailed steady-state analysis carried out here increases the precision of the first-harmonic analysis of a previous work, which is especially important with distorted output currents due to low load quality factors or highly asymmetrical modulation strategies. The theoretical results are verified experimentally.     

Logic drive circuit for 3-phase charge-coupled devices

A simple logic circuit is escribed which acts as a modulo-3 ring counter and provides three driving phases suitable to operate a 3-phase c.c.d. The circuit is driven by a clock, the rate of which corresponds to three times the desired element rate in the c.c.d. The pulsewidth of the clock determines the amount of mutual overlap between subsequent phases. An additional gating input permits stopping the counter in a predetermined state, such as would be required to switch a c.c.d. into the integration mode. The circuit contains only 12 gates, and when implemented with a t.t.l. high-speed logic component runs up to input clock rates of 50 MHz.     

High-performance SAW convolver using 3-phase unidirectional transducers

The development of a new SAW convolver with a bandwidth 45 MHz, interaction time 12 ?s and which employs 3-phase unidirectional transducers is discussed. The resulting device has high efficiency (?58 dBm) and displays good self-convolution suppression. Only single-stage fabrication is required.     

High-performance current control techniques for application tomultilevel high-power voltage source inverters

Several high-performance current control techniques are developed for applications to multilevel high-power voltage source inverters (VSIs). The logical sequence of the design choices is described, resulting in a very robust and reliable control system that allows an adequate switching optimization, excellent dynamic responses, and high accuracy in steady-state operation. The advantages of using various accessible DC potentials are fully exploited. The validity of the proposed schemes has been confirmed by digital simulations involving the generation of five-level voltage waveforms; however, the current control strategies developed can easily be extended to any multilevel inverter structure, even in the case of n-level voltage waveforms and three-phase systems     

Application of neural networks to the optimal control ofthree-phase voltage-controlled inverters

A novel concept of application of neural networks for generation of optimal switching patterns in voltage-controlled inverters is described. The pulsewidth modulator (PWM), based on hardware analog neural networks, responds with high accuracy to any desired value of the modulation index. No microprocessor or large memory typical for the existing optimal PWM schemes is required. Theoretical analysis of the proposed so-called sparse neural network is provided, and experimental results that confirm the high performance and technical advantages of the developed modulator are presented