FPGA realization of space-vector PWM control IC for three-phase PWMinverters

This paper presents a new circuit realization of the space-vector pulse-width modulation (SVPWM) strategy. An SVPWM control integrated circuit (IC) has been developed using state of-the-art field-programmable gate array (FPGA) technology. The proposed SVPWM control scheme can be realized using only a single FPGA (XC4010) from Xilinx, Inc. The output fundamental frequency can be adjusted from 0.094 to 1500 Hz. The pulse-width modulation (PWM) switching frequency can be set from 381 Hz to 48.84 kHz. The delay time for the PWM gating signals is adjustable. This SVPWM IC can also be included in the digital current control loop for stator current regulation. The designed SVPWM IC can be incorporated with a digital signal processor (DSP) to provide a simple and effective solution for high-performance AC drives. Simulation and experimental results are given to verify the implemented SVPWM control IC     

Interleaved PWM with discontinuous space-vector modulation

This paper describes the effect of interleaved discontinuous space-vector modulation (SVM) in paralleled three-phase systems using three-phase pulsewidth modulation (PWM) rectifiers as an example. At the discontinuous point of the SVM, the phase shift between the switching signals of the paralleled modules generates a zero-sequence excitation to the system. Because the conventional control in a balanced three-phase system with only dq channels cannot reject this disturbance, a beat-frequency circulating current will develop on the zero axis. Based on this observation, a SVM without using zero vectors is used to eliminate the cause of pure zero-sequence current for parallel operation. Using this SVM, the circulating current is observable in dq channels. It can be suppressed dynamically by strong current loops of power-factor-correction (PFC) circuits. The concept is verified experimentally on a breadboard system     

Relationship between space-vector modulation and three-phasecarrier-based PWM: a comprehensive analysis [three-phase inverters]

This paper comprehensively analyzes the relationship between space-vector modulation and three-phase carrier-based pulse width modulation (PWM). The relationships involved, such as the relationship between modulation signals (including zero-sequence component and fundamental components) and space vectors, the relationship between the modulation signals and the space-vector sectors, the relationship between the switching pattern of space-vector modulation and the type of carrier, and the relationship between the distribution of zero vectors and different zero-sequence signal are systematically established. All the relationships provide a bidirectional bridge for the transformation between carrier-based PWM modulators and space-vector modulation modulators. It is shown that all the drawn conclusions are independent of the load type. Furthermore, the implementations of both space-vector modulation and carrier-based PWM in a closed-loop feedback converter are discussed     

Real-time multi-DSP control of three-phase current-source unitypower factor PWM rectifier

The design of a real-time multi-DSP controller for a high-quality six-valve, three-phase current-source unity power factor pulse-width-modulated (PWM) rectifier is discussed. With the decoupler preprocessor and the dynamic trilogic PWM trigger scheme, each of the three input currents can be controlled independently. The pole-placement control method implemented, which is based on the a-b- c frame system model and fast parallel computer control, achieves fast AC current response. The low-frequency resonance in the AC filter L-C networks is damped effectively. The experimental results were obtained for a 1 kVA bipolar transistor current-source PWM rectifier with a real-time controller using three TMS320C25 DSPs     

Minimum-loss strategy for three-phase PWM rectifier

In this paper, the conduction and switching losses of a voltage-fed three-phase pulsewidth modulation (PWM) rectifier are analyzed for various PWM schemes. On the basis of this result, a novel PWM strategy which minimizes the loss of a three-phase PWM rectifier is developed. This minimization result is derived from the following two factors: (1) less switching frequency ratio; and (2) the absence of switching in the vicinity of peak input current. As a result, it is anticipated that the switching loss of the rectifier is reduced by 46%, compared with continuous space-vector PWM rectifiers, and 20% compared with conventional discontinuous space-vector PWM rectifiers. Moreover, the proposed PWM scheme can produce the highest available output voltage because it is based on the concept of the voltage space vector. The effectiveness of the proposed PWM strategy is verified by experiments     

Fuzzy logic control of a space-vector PWM current regulator forthree-phase power converters

This paper presents a fuzzy logic implementation of space-vector pulse-width modulation (PWM) for three-phase power converters. The conventional space-vector PWM current regulator implementation is generally computationally complex. The fuzzy logic controller implementation relieves the processor of a number of computations, thereby accommodating a less expensive microprocessor. The AC-side rectifier voltages are used as fuzzy-state variables. The fuzzy logic control has two outputs: magnitude and angle of reference voltage. Both conventional space-vector PWM and the fuzzy logic controller are implemented to evaluate performance using a 16-b microcontroller (68HC16). Experimental results are provided for both controllers at the same operating point, where the power drawn by the load is about 3 kW. The fuzzy logic controller reduces the computational burden on the processor by about 30%     

Control of a three-phase PWM rectifier using estimated AC-side andDC-side voltages

A new control method of a pulsewidth modulation (PWM) rectifier without measuring AC- and DC-side voltages is proposed. As information about these voltages is necessary for the controller, all required voltage values are estimated from the measured line currents and the calculated values of the input reactor voltage during switching of the rectifier circuit. The input reactor voltage can be obtained by using a differentiator that produces the derivative of the line current or by detecting the voltage induced in a secondary winding wound on the input reactor. The secondary winding creates the electric isolation between the main circuit and the controller. The proposed method is verified by experiment. This paper describes the estimation method, gives the configuration of the controller, and discusses steady-state and transient performances of the rectifier     

三相电压型PWM整流器新型双闭环控制策略研究

针对三相电压型PWM整流器交流侧电感值实际控制系统中存在误差,往往忽略掉耦合项,以及系统参数变化影响整流器的动、静态性能等问题,提出了一种新型的双闭环控制策略。其中电流内环采用同步旋转d-q坐标系下无电感L参数的解耦控制与内模控制相结合的方法,电压外环采用滑模控制,在Matlab中利用Simulink工具箱搭建三相电压型PWM整流器数值仿真数学模型,数值仿真结果表明系统仍获得了较好的动、静态性能,鲁棒性强。并通过实验平台验证该控制策略的正确性和优越性。     

A new control algorithm for three-phase PWM buck rectifier withinput displacement factor compensation

A new control algorithm for the three-phase buck rectifier with an input filter is developed. The algorithm employs a separate control loop for compensation of the input current displacement factor in steady-state, in addition to the standard output voltage regulation loop. The algorithm allows separate design of the input filter and of closed-loop output voltage control. The design procedure is explained and illustrated with an example. The algorithm is verified experimentally on a 1 kW, 100 kHz, three-phase isolated buck converter     

Simple direct torque control of induction machine using space vector modulation

A new method for direct torque control (DTC) based on load angle control is developed. The use of simple equations to obtain the control algorithm makes it easier to understand and implement. Fixed switching frequency and low torque ripple are obtained using space vector modulation, overcoming the most important drawbacks of classic DTC.     

A three-phase half-controlled rectifier with pulse width modulation

A three-phase pulse-width-modulated (PWM) half-controlled rectifier using a novel PWM control strategy whereby the low-order harmonic content in both the input current and the output voltage is reduced is presented. The circuit operates with a unity displacement factor at its input and uses minimum power components. The PWM strategy developed can be implemented on a three-phase half-controlled rectifier bridge with only three controlled switches to obtain PWM controlled rectification. Although the circuit operation is explained with force-commutated SCR switches, the basic controlled PWM operation is valid for any type of switch control. The circuit has wide applications ranging from rectifiers to battery chargers to motor drives. Even if an input current filter is desired, its size will be small due to the PWM pattern used     

A novel discrete control strategy for independent stabilization of parallel three-phase boost converters by combining space-vector modulation with variable-structure control

We propose a discrete nonlinear controller, developed in a synchronous frame, for a parallel three-phase boost converter consisting of two modules. The basic idea, however, can be extended to a system with N modules. Each of the closed-loop power-converter modules operates asynchronously without any communication with the other modules. The controller stabilizes the currents on the dq-axes and limits the flow of the pure-zero sequence current. It combines the space-vector modulation scheme with a variable-structure control, thereby keeping the switching frequency constant and achieving satisfactory dynamic performance.     

一种新型开关表的PWM整流器直接功率控制

为了提高三相电压电压型PWM整流器的性能,改善传统开关表的直接功率控制时开关损耗大且不固定,以及有功功率和无功功率控制解耦能力不足的问题,文中通过对PWM整流器和瞬时功率理论研究的基础上,提出一种基于三电平比较器的新的开关表直接功率的方法,并通过设置扇形边界死区的控制策略细分开关表,这种新开关表通过消除两个扇区中间区域的错误控制,能较好的降低主电路开关频率,增加功率控制性能,使交流侧电流输入谐波率更小,提高整流器的功率因数。在MATLAB/Simulink环境下,对改进前后直接功率控制的稳态性能进行比较,验证了该设计方法的可行性,具有应用参考价值。     

峰值电流控制提高三相整流功率因数的方法

在对大电容滤波的三相不控整流电路仿真研究的基础上,指出了该电路存在的工程应用局限性。在分析电流谐波畸变与功率因数之间的理论关系的基础上,提出了一种峰值电流控制提高三相不控桥式整流电路功率因数的方法,并进行了试验验证,证明其在提高功率因数的同时,有效地降低了滤波电感的体积及重量,实现三相整流滤波电路的小型化设计,具有一定的工程应用价值。     

Indirect current control of a unity power factor sinusoidal currentboost type three-phase rectifier

The indirect current control scheme has evolved from the success of the hysteresis current controlled voltage regulated rectifier, which has been shown to be capable of: unity and even leading power factor operation; near sinusoidal current waveforms; and bilateral power transfer without the need of bi-directional solid state power switches. The advance consists of replacing the inner hysteresis current feedback loop by the standard sinusoidal PWM control and in the process saving the cost of the current measuring transducers. The scheme is evaluated through tests on 1 KW size laboratory models and through digital simulations. A theory of the system dynamics is developed and stability boundaries are presented     

New space-vector control strategies for three-phase step-up/downAC/DC converter

In this paper, an equivalent DC duty cycle for the generalized zero-voltage space vectors is proposed such that control of the three-phase AC part and the DC part of the converter circuit can be integrated to achieve the ideal characteristic of single-stage step-up/down AC/DC converter. Depending upon how many modes are chosen and which class of generalized zero-voltage space vectors is selected to increase the equivalent DC duty cycle, different control strategies can be obtained. It is seen that not only the control of the six switches is simplified but also the deadtime circuit for avoiding short circuit of the same arm can be eliminated for the proposed converter. In addition, some guidelines for selecting the LC parameters are described briefly and experimental results given for verifying the validity of the proposed converter     

Optimal operation of single-stage three-phase power factorcorrection circuit using modular PWM DC-to-DC converters

A critical conduction parameter K_3Φ is derived for the three-phase modular system. This parameter optimises the output filter to achieve the highest power factor of the system. The voltage conversion ratio required to achieve a high power factor to fulfil the harmonic requirements is also derived. Both simulations and experimental results from a 1.5 kW prototype using full-bridge converters have confirmed the analysis     

Active filtering function of three-phase PWM boost rectifier under different line voltage conditions

Slight hardware and algorithm modifications as well as a higher power ratio of a three-phase pulsewidth-modulation (PWM) rectifier make compensation of neighboring nonlinear power load possible. The active filtering function enlarges the functionality of PWM rectifiers, which decreases the cost of additional installation of compensating equipment. It gives a chance to fulfill both shunt active filter (SAF) and PWM rectifier tasks in a multidrive system by one advanced converter. Thanks to the idea of virtual flux, the direct power control space-vector-modulated (DPC-SVM) and new synchronous double reference frame phase-locked loop approach, the control system is resistant to a majority of line voltage disturbances. This assures proper operation of the system for abnormal and failure grid conditions. Simulation and experimental results have proven excellent performance and verify the validity of the proposed system.     

A novel load current control method for a leading power factorvoltage source PWM rectifier

A novel PWM voltage source rectifier, controlled by the load DC current instead of the DC voltage, has been developed. Its main characteristics are: (a) there is neither input current sensors nor DC voltage sensor; (b) it works with an unchangeable and predefined PWM pattern; (c) it presents a very strong stability; (d) its stability does not depend on the size of the DC capacitor; (e) it can work at leading power factor for all load conditions; and (f) it can also work with zero regulation for all load conditions. Digital simulations, analyses, and experiments confirm all these characteristics of the control method     

A novel control method for three-phase PWM rectifiers using asingle current sensor

This paper proposes a control method for three-phase voltage-source PWM rectifiers using only a single current sensor in the DC-link. A PWM modulation strategy for reconstructing three phase currents from the DC-link current is given. When 3φ input currents cannot be reconstructed, a method for modifying the switching state of the PWM rectifier and a method for the predictive state observer is proposed. Compensation of the 2 sampling delays is also included, and this method is combined with all of the experiments. Performance differences between the two methods in a typical voltage source PWM rectifier are investigated experimentally