一种改进的单相逆变器重复控制方案

提出一种新的重复控制方案,通过电容电流内环反馈,消除逆变器固有的谐振峰,简化了重复控制器的设计;改进内模中的Q（z）,采用零相移低通滤波器,提高了系统的稳态精度。Matlab仿真结果表明,该控制方案可以获得高质量的电压输出,在非线性负载条件下THD仅为0.65%,稳态误差只有0.12%。     

Design method of single-phase inverters for UPS systems

This article presents the complete design of a low power voltage source inverter (VSI) dedicated for a UPS system. The analysis of the rectangular PWM-AC voltage spectrum allows for a choice of the basic architecture of the inverter. Output filter parameters were calculated to reduce the maximum amplitude of the output VSI voltage harmonics for the steady-state inverter mode. The choice of the feedback loop type was based on a discussion of the inverter output impedance using a continuous model of the inverter. The parameters of the inner loop digital control for the discrete inverter model were calculated using the Coefficient Diagram Method. The influence of the step load was modelled. The time constant of the inverter closed loop system was selected to ensure sufficient system robustness. An outer feedback loop with a plug-in repetitive controller, simplified owing to the properties of the PID/CDM inner loop control, was introduced to eliminate the periodic disturbances generated by the non-linear rectifier load and the deadtime influence. The experimental verification of the design method is presented.     

重复控制在IGBT逆变电源中的应用

为了有效解决由非线性负载和死区等因素引起的输出波形畸变问题,提高稳态控制精度,研究并实现了基于重复控制算法的单相逆变电源。研究工作主要集中在建立单相逆变电源的数学模型和状态方程;分析重复控制器的基础理论和稳定性,详细讨论周期延时环节、超前环节、补偿环节的陷波器、二阶低通滤波器等各组成部分的设计方案,总结出工程实用的重复控制器设计步骤;利用MATLAB/Simulink进行建模和仿真分析;对控制系统的核心算法使用基于模型的设计方法,直接生成C代码;最终在3KVA的单相IGBT逆变电源实验样机上进行算法验证。实验结果表明该方案的有效性和可行性。     

Reducing the manufacturing costs associated with hard disk drives-a new disturbance rejection control scheme

A new disturbance rejection control scheme is developed for cost-effective hard disk drive manufacturing. The proposed disturbance rejection controller is capable of attenuating both repeatable disturbances and nonrepeatable disturbances, which are two of the major detractors to hard disk drive quality and performance. The control scheme overcomes the drawback of typical internal-model-based repetitive control schemes which cancel repeatable disturbances, but amplify disturbances at other frequencies. This is achieved by a systematic combination of the internal-model-based repetitive controller with a loop shaping filter. It is shown that the internal-model-based repetitive controller is a special case of the proposed controller. Robustness of the controller is also studied. Simulations using disturbances reconstructed from actual drive level position error signal (PES) measurements have been carried out to show the effectiveness of this control scheme.     

Digital repetitive learning controller for three-phase CVCF PWMinverter

In this paper, a plug-in digital repetitive leaning control scheme is proposed for three-phase constant-voltage constant-frequency (CVCF) pulsewidth modulation inverters to achieve high-quality sinusoidal output voltages. In the proposed control scheme, the repetitive controller (RC) is plugged into the stable one-sampling-ahead-preview-controlled three-phase CVCF inverter system using only two voltage sensors. The RC is designed to eliminate periodic disturbance and/or track periodic reference signal with zero tracking error, The design theory of plug-in repetitive learning controller is described systematically and the stability analysis or overall system is discussed. The merits of the controlled systems include features of minimized total harmonic distortion, robustness to parameter uncertainties, fast response, and fewer sensors. Simulation and experimental results are provided to illustrate the effectiveness of the proposed scheme     

电压型逆变器输出波形控制技术

文中将目前逆变器输出波形控制技术分为基于周期的控制和瞬时值反馈控制。基于周期的控制是通过对误差的周期性补偿,实现稳态的无静差效果,主要包括重复控制和谐波反馈控制。瞬时值反馈控制利用快检测,及时对逆变器的输出波形进行校正,主要包括瞬时值内环反馈控制、PID（单闭环）控制、双闭环控制、线性多变量状态反馈控制等。在对这些控制方法的特点作了相应的分析,从波形控制的实际要求出发,提出了最有前途的方案。     

A discretized current control technique with delayed input voltagefeedback for a voltage-fed PWM inverter

A current control technique for a voltage-fed PWM inverter is presented. The discretized state equation of an inverter and a load independent of operating conditions with the delayed input voltage feedback has been derived using the averaging concept. The discretized current controller is proposed to reduce the current error as fast as possible using the deadbeat control strategy and to stabilize the closed loop system asymptotically when the variations of load parameters are given in the predetermined stabilized region. This proposed control scheme is realized by the symmetrical uniform sampling method and is easily implemented using a microprocessor-based system. Computer simulation for the proposed controller has been carried out and the results show good static and dynamic performances     

Admittance Compensation in Current Loop Control for a Grid-Tie LCL Fuel Cell Inverter

Current loop transfer function of a single-phase grid-tie inverter has been systematically derived with representations of conventional transfer function format using admittance terms for controller design and loop compensation. The power circuit adopts the LCL type filter to allow universal output that can be operated in both standalone and grid-tie modes. The proposed admittance compensation along with a quasi-proportional-resonant controller is designed to achieve high gain at the fundamental frequency while maintaining enough stability margins. The entire current loop controller and admittance compensation have been simulated and tested with a 5-kW fuel cell prototype. Without the admittance path compensation, simulation results indicate that the system cannot start up smoothly and the zero current command cannot be tracked very well. At first simulation cycle, the power flow erratically fed back to the inverter that may cause catastrophe failure. With admittance path compensation, the time-domain current steady-state error can be easily reduced with the loop gain design in frequency-domain. Simulation and experimental results show that the inverter is capable of both standalone and grid-tie connection mode operations and smooth power flow control even with zero current command.      

Digital control of three-phase PWM inverter with LC filter

A digital control algorithm for the three-phase sinusoidal voltage inverter with an output LC filter has been developed. To take the transient of the LC filter during the discretization time into consideration, a fourth-order matrix state equation of the current and the voltage on the d-q frame is discretized. Precise discrete equations for the inverter are introduced. Using these equations, a deadbeat controller consisting of a d-g current minor loop and a d-q voltage major loop, with precise decoupling of the d-q components, was developed. The voltage major loop controller assures the sinusoidal output voltage and stabilizes the system. A deadbeat controller is used because both the current minor loop and the voltage major loop can used one sampling response. The validity of these techniques is confirmed by simulation studies. This method is expected to be useful for direct digital control of large-capacity sinusoidal voltage inverters using low-switching-frequency devices     

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.     

Microprocessor based robust digital control for UPS withthree-phase PWM inverter

This paper describes a novel method of robust (insensitive to system parameter variations and load current changes) and fast digital control for an uninterruptible power supply (UPS) with a three-phase PWM inverter. The purpose of this paper is to propose a method by which characteristics better than those by conventional methods are obtained using an algorithm simpler than that of conventional methods. The experiments show that the purpose is achieved and the proposed method offers a total harmonic distortion of 0.6% of the output voltage waveform at a full nonlinear load. The analysis shows that the stability of the method is sufficient. Three features of the method are: (a) a capacitor current observer for stabilization and a disturbance observer for robustness are used to compensate the time lag by the computation and the disturbances, in a minor loop of the capacitor current through an inductor-capacitor filter of the inverter; (b) new models of the inverter and the disturbances are established to simplify these observers; and (c) the output voltage control loop can be designed easily and exactly because the minor loop realizes a rapid and robust control of the current     

Quasi-Z Source Inverter Control of PV Grid-Connected Based on Fuzzy PCI

The photovoltaic grid-connected inverter is an important interface between the photovoltaic power generation system and power grid. Its high-quality operation is directly related to the output power quality of the power grid. In order to further optimize the control effect of the quasi-Z source grid-connected photovoltaic inverter, a fuzzy proportional complex integral control (PCI) method is proposed for the current internal loop control. This method can eliminate the steady-state error, and has the characteristic of zero steady-state error adjustment for the AC disturbance signal of a specific frequency. The inductance-capacitance-inductance (LCL) filter is adopted in the grid-connected circuit, and the feedback capacitive current is taken as the control variable of the inner loop to form the active damping control method, which can not only effectively suppress the resonance of the LCL circuit, but also significantly inhibit the high-order harmonics in the grid-connected current. Finally, a system simulation model is built in MATLAB/Simulink to verify the superiority and effectiveness of the proposed method.     

逆变器重复控制器设计与仿真

针对实际应用给出了重复控制器内模、补偿器以及周期延迟环节的优化设计方法,推导出了重复控制器的稳定性判断条件和收敛指数。基于3 kVA逆变器硬件和控制参数设计了重复控制器,给出了重复控制器各关键参数的设计过程,并进一步基于重复控制器稳定性判断条件对设计结果进行了稳定性验证。利用Matlab软件对设计结果进行了验证,仿真结果表明在逆变器控制中添加重复控制器后,能明显降低逆变器带非线性负载时输出电压的总谐波失真度值。     

Adaptive repetitive control of PWM inverters for very low THDAC-voltage regulation with unknown loads

An adaptive repetitive control scheme is proposed and applied to the control of a pulsewidth-modulated (PWM) inverter used in a high-performance AC power supply. The proposed control scheme can adaptively eliminate periodic distortions caused by unknown periodic load disturbances in an AC power supply. The proposed adaptive repetitive controller consists of a voltage regulator using state feedback control, a repetitive controller with tuning parameters and an adaptive controller with a recursive least-squares estimator (LSE). This adaptive repetitive controller designed for AC voltage regulation has been realized using a single-chip digital signal processor (DSP) TMS320C14 from Texas Instruments. Experimental verification has been carried out on a 2 kVA PWM inverter. Simulation and experimental results show that the DSP-based adaptive repetitive controller can achieve both good dynamic response and low total harmonic distortion (THD) under large-load disturbances and uncertainties     

Current Weighting Distribution Control Strategy for Multi-Inverter Systems to Achieve Current Sharing

A current-weighting-distribution-control (CWDC) strategy for multi-inverter systems to achieve current sharing is presented in this paper. With a CWDC strategy, the inverters connected in parallel are allowed to have different power ratings and can achieve a weighted output current distribution by adding only simple circuits to each inverter. In such systems, each inverter has an outer voltage loop controller to govern system stability, an inner current loop controller to expedite dynamic response, and a weighting current controller to achieve current distribution and to reduce possible interactive effects among inverters. Experimental results from a two-inverter system and a three-inverter system have demonstrated the feasibility of the proposed strategy in weighting current distribution and fast regulation during a step-load change or hot-swap operation     

基于直接转矩控制的两轮自平衡车系统设计

两轮载人自平衡车控制系统是一种典型的类倒立摆动态平衡控制系统,为降低成本,提高系统操控性能,该文利用新型ARM微处理器STM32F373为控制核心,结合惯性传感器MPU6050,进行了平衡车控制方案设计。该文提出了电机的直接转矩控制法,并利用改进后的显性互补滤波算法得到车体倾斜角度的实时最优值,形成了以角度环、角速度环及电流环所构成的三闭环串级比例-积分-微分(PID)控制方式,实现了车辆的自平衡行驶。与传统使用电压开环控制及速度反馈控制的平衡车相比,该文设计的平衡车具有性价比高、响应速度快、控制平稳等优点。     

Three-Level Inverter-Based Shunt Active Power Filter in Three-Phase Three-Wire and Four-Wire Systems

This paper presents a direct current-space-vector control of an active power filter (APF) based on a three-level neutral-point-clamped (NPC) voltage-source inverter. The proposed method indirectly generates the compensation current reference by using an equivalent conductance of the fundamental component using APF's dc-link voltage control. The proposed control can selectively choose harmonic current components by real-time fast Fourier transform to generate the compensation current. The compensation current is represented in a rotating coordinate system with chosen switching states from a switching table implemented in a field-programmable gate array. In addition, a three-phase four-wire APF based on a three-level neutral-point-clamped inverter is also presented. The proposed APF eliminates harmonics in all three phases as well as the neutral current. A three-phase three-wire NPC inverter system can be used as a three-phase four-wire system since the split dc capacitors provide a neutral connection. To regulate and balance the split dc-capacitor voltages, a new control method using a sign cubical hysteresis controller is proposed. The characteristics of the APF system with an LCL-ripple filter are investigated and compared with traditional current control strategies to evaluate the inherent advantages. The simulation and experimental results validated the feasibility of the proposed APF.      

High-performance programmable AC power source with low harmonicdistortion using DSP-based repetitive control technique

This paper proposes a new control scheme based on a two-layer control structure to improve both the transient and steady-state responses of a closed-loop regulated pulse-width-modulated (PWM) inverter for high-quality sinusoidal AC voltage regulation. The proposed two-layer controller consists of a tracking controller and a repetitive controller. Pole assignment with state feedback has been employed in designing the tracking controller for transient response improvement, and a repetitive control scheme was developed in synthesizing the repetitive controller for steady-state response improvement. A design procedure is given for synthesizing the repetitive controller for PWM inverters to minimize periodic errors induced by rectifier-type nonlinear loads. The proposed control scheme has been realized using a single-chip digital signal processor (DSP) TMS320C14 from Texas Instruments. A 2-kVA PWM inverter has been constructed to verify the proposed control scheme. Total harmonic distortion (THD) below 1.4% for a 60-Hz output voltage under a bridge-rectifier RC load with a current crest factor of 3 has been obtained. Simulation and experimental results show that the DSP-based fully digital-controlled PWM inverter can achieve both good dynamic response and low harmonics distortion     

Parallel processing inverter system

A novel method of instantaneous voltage and power balance control of a parallel processing inverter system is proposed. It consists of a high-speed switching PWM (pulsewidth modulated) inverter with an instantaneous current minor loop controller, a voltage major loop controller, and a power balance controller. This system realizes the following functions with only one inverter: constant AC output voltage control with reactive power control, active filtering to absorb load current harmonics, DC voltage and current control as AC-to-DC converter, and uninterruptible power supply (UPS) for stand-alone operation. This system covers a wide application range, including UPS systems, new energy systems, and active filters with voltage control functions     

Sliding-mode control in voltage source inverter-based higher-order circuits

In this article, a new control methodology of sliding-mode control (SMC) for voltage source inverter (VSI)-based higher-order circuit is proposed. In this method, the SMC is used at the inner terminals for stable tracking of the voltage and current variables. An outer voltage control loop is included to reduce the steady-state error in tracking the reference load voltage. It is shown that when the SMC is applied on the load voltage terminal for higher-order VSI circuits, it leads to the instability. However, it well stabilises the system when the controller is implemented on the inner shunt capacitor terminals. Additional outer voltage control loop with proportional plus integral controller will ensure regulated voltage across the load. It has been shown that the controller is able to achieve good tracking accuracy with an acceptable stability margins. The performance of the proposed SMC has been verified on the fourth-order VSI circuit.