A power-factor controller for single-phase PWM rectifiers

A novel power-factor controller for single-phase pulsewidth modulated rectifiers is proposed. The unity power-factor controller for a sinusoidal input current is derived using the feedback linearization concept. Two active switches and two diodes are utilized for AC-to-DC power conversion. Experimental results obtained on a 4 kW prototype are discussed     

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 new PWM controller with one-cycle response

This paper proposes a new nonlinear control technique that has one-cycle response, does not need a resetable integrator in the control path, and has nearly constant switching frequency. It obtains one-cycle response by forcing the error between the switched variable and the control reference to zero each cycle, while the on and off pulses of the controller are adjusted each cycle to ensure near constant switching frequency. The small switching frequency variation due to changes in the reference signal and supply voltage and delays in the circuit are quantified. Using double-edge modulation, the switching frequency variation is further reduced, thus, the associated signal distortion is minimized. An experimental 0-20 kHz bandwidth 95 W RMS power audio amplifier using the control method demonstrates the applicability of this control technique for high-fidelity audio applications. The amplifier has a power supply ripple rejection (PSRR) of 63 dB at 120 Hz. Additionally, the total harmonic distortion plus noise (THD+N) is less than 0.07% measured with a power supply ripple of 15%     

A single-phase controlled-current PWM rectifier

The analysis and test results are given for an experimental single-phase controlled-current PWM (pulse-width-modulated) rectifier that operates at unity power factor with near sinusoidal current waveform and that has power reversal capability. The twice-line-frequency AC power is identified as a source of voltage harmonics in the DC link. The harmonics enter into the voltage regulation feedback loop to distort the AC current waveform. These undesirable harmonics can be removed by a low-pass filter. It is noted that the overall design must address the possibility of instability due to the low-pass filter in the feedback path     

A high-power PWM quadrature booster phase shifter based on amultimodule AC controller

Pulse-width-modulated (PWM) phase shifters allow the smooth control of power flow in a transmission line. This paper analyzes a PWM quadrature booster phase shifter based on a multimodule AC controller structure to attain high voltage levels and improve the harmonic spectrum. The modules are based on a three-phase PWM AC controller topology that employs only four force-commutated switches and is controlled by duty-cycle variation. The PWM technique is carrier based and the individual modules are gated through phase-shifted triangular carriers. As a result, harmonic cancellation takes place in the input current and output voltage. Low-order harmonics are therefore eliminated and the amplitude of remaining components reduced. An additional operating mode with negligible harmonic generation and step-like control is identified. The feasibility and advantages of the proposed phase shifter are demonstrated by means of a power system simulator     

A new single-phase five-level PWM inverter employing a deadbeat control scheme

A single-phase five-level PWM inverter is presented to alleviate harmonic components of the output voltage and the load current. Operational principles with switching functions are analyzed. To keep the output voltage sinusoidal and to have the high dynamic performances even in the cases of load variations and the partial magnetization in filter inductor, the deadbeat controller is designed and implemented on a prototype. The validity of the proposed inverter is verified through simulation and experiments. To assess the proposed inverter, it is compared with the conventional single-phase three-level PWM inverter under the conditions of identical supply DC voltage and switching frequency. In addition, it is compared with the five-level cascaded PWM inverter.     

A new control scheme for single-phase PWM multilevel rectifier withpower-factor correction

A new control scheme for a single-phase bridge rectifier with three-level pulsewidth modulation is proposed to achieve high power factor and low current distortion. The main circuit consists of a diode-bridge rectifier, a boost inductor, two AC power switches, and two capacitors. According to the proposed control scheme based on a voltage comparator and hysteresis current control technique, the output capacitor voltages are balanced and the line current will follow the supply current command. The supply current command is derived from a DC-link voltage regulator and an output power estimator. The major advantage of using a three-level rectifier is that the blocking voltage of each AC power device is clamping to half of the DC-link voltage and the generated harmonics of the three-level rectifier are less than those of the conventional two-level rectifier. There are five voltage levels (0, ±V_DC/2, ±V_DC) on the AC side of the diode rectifier. The high power factor and low harmonic currents at the input of the rectifier are verified by software simulations and experimental tests     

A mixed-mode PWM controller

In this article, a mixed-mode (MM) PWM controller for dc–dc power converter topologies is presented and analysed. Compared to the conventional peak current-mode (PCM) controller, the proposed controller exhibits better results in terms of robustness towards load and reference voltage variations while maintaining better dynamic response. In the PCM controller, the control signal is a combination of inductor or, most often, switch current and a suitable compensation ramp which in the most common applications is constant. In the proposed controller, the constant compensation ramp has been replaced by a ramp voltage which is proportional to the output voltage taking into consideration the output voltage variations during load and reference transients. Consequently, the proposed controller, which exhibits the same advantages as with the PCM controller, additionally exhibits better load and reference performance for constant output voltage and output tracking applications without increasing the cost and the complexity of the control circuit. Finally, in order to verify the theoretical analysis and conclusions, both control schemes (i.e. PCM and MM) have been simulated and experimentally tested using a 75 W buck converter unit.     

A DSP-based single-phase AC power source

This paper presents the development of a single-phase AC power source, which is capable of generating high-quality sinusoidal waveforms with adjustable amplitudes and frequencies over a wide range. Moreover, various types of arbitrary waveforms can also be generated. The system consists essentially of a well-controlled single-phase pulsewidth modulated inverter. To perform tight closed-loop control of the inverter, a digital controller based on the generalized predictive control approach has been developed. The controller gains are determined by minimizing a cost function that reduces both the tracking error and the control signals. To evaluate the proposed approach, a digital-signal-processor-based experimental prototype has been constructed. Experimental results under various loading conditions have demonstrated that the system performs well     

A novel PWM scheme for single-phase three-levelpower-factor-correction circuit

This paper presents a control scheme for a single-phase AC-to-DC power converter with three-level pulsewidth modulation. A single-phase power-factor-correction circuit is proposed to improve the power quality. The hysteresis current control technique for a diode bridge, with two power switches is adopted to achieve a high power factor and low harmonic distortion. A control scheme is presented where the line current is driven to follow the reference sinusoidal current which is derived from the DC-link voltage regulator, the capacitor voltage balance compensator and the output power estimator. The blocking voltage of each power device is clamped to half of the DC-link voltage. The high power factor and low current total harmonic distortion are verified by computer simulations and hardware tests     

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     

A single-phase PCS with a novel constantly sampledcurrent-regulated PWM scheme

The error-tracking mode (ETM) is a novel constantly sampled pulsewidth modulation (PWM) scheme for a voltage-source power conversion system (PCS) interconnecting with a utility network to regulate its AC current waveform. It guarantees, theoretically, the AC actual current to be settled within an arbitrary target allowable error. Generated current harmonics can be restricted by a relatively small filter. Both the minimum on- and off-duration times of switching commands are assured by the PWM scheme itself. A four-quadrant 1-kVA PCS in which gate commands are produced by the novel PWM scheme has been successfully experimented upon for the first time, and it has justified the ETM-PWM theory. This paper describes the design procedure and experimental results of the trial setup     

Control of the single-phase three-leg AC/AC converter

This paper investigates the control of a single-phase three-leg ac/ac reversible converter in which a leg is shared by both the grid and the load side. Pulsewidth-modulation (PWM) techniques based on scalar and vector approaches are developed, introducing the concept of local and general apportioning factor and, also, a complete equivalence between scalar and space vector PWM. A hysteresis current controller capable of taking into account the shared leg is developed and a zero current error linear controller is presented. Furthermore, a control strategy to obtain maximum utilization of the dc-bus voltage is proposed. In addition, several relevant characteristics of the converter are addressed, such as voltage rating, harmonic distortion, shared leg and capacitor currents, and power rating. The converter is compared to four-leg and two-leg converters. Experimental results are presented.     

电流型PWM整流器的控制器设计

电流型PWM整流器因其良好的功率因数和直流电流源特性,可望在某些场合取代产生大量谐波的二极管或晶闸管相控整流装置,但是由于其本身的强耦合非线性特性,使得变流器常采用复杂的直接电流控制策略,从而使控制器的设计非常复杂。文中提出一种改进的基于d-q坐标系的间接电流控制方法,在电网电压平衡情况下,通过解耦控制,能获得线性的动态响应。     

A new state feedback based transient control of PWM AC to DCvoltage type converters

This paper presents a new state feedback based control strategy for a PWM AC to DC voltage type converter with phase and amplitude control. In this control strategy the state variables of the LC filter connected to the AC side of the converter are fed back to the PWM pattern generator, thereby eliminating a DC offset of the AC input currents as well as oscillations of the DC output current during transients. Computer simulation of the converter system with the proposed control strategy shows that the transient waveforms of AC input and DC output currents are improved greatly even if the damping effect of the AC side resistance can not be expected. The DC voltage regulation with good dynamic response is also achieved even if DC capacitance is substantially reduced. Experimental results from a low power laboratory model are also included to confirm the simulated results and to demonstrate the effectiveness of the proposed control strategy     

一种新型的单相数字锁相环

本文提出了一种新型的高精度数字锁相环（DPLL）技术,以一个改进的鉴相器（PD）环节代替常用的二阶通用积分器构成的PD环节,为了抑制该方法在同步信号频率上引入的二次谐波干扰,本文分析了引入谐波的原因,提出针对同步信号频率二次谐波的带阻滤波器,并研究了基于FPGA的数字锁相环实现方法。该方法锁相精度高,速度快,结构简单,计算量较小。仿真和实验结果表明该方法是有效可行的。     

移相型PWM控制器UCC3895

详细介绍了移相型PWM控制器UCC3895的特性、引脚功能、主要参数、工作原理以及典型应用电路等。     

Fast controller design for single-phase power-factor correctionsystems

A fast controller is presented for single-phase boost-type power factor correction circuits. The twice-line-frequency ripple component is removed from the measured output voltage with an adaptive estimator. This enables the closed-loop time constants and overshoots to be reduced by two orders of magnitude compared to traditional designs. The controller copes with considerable uncertainty in input voltage magnitude, line frequency and output capacitance. All sections of the control system are shown to be asymptotically stable. Experimental results are presented to verify the excellent dynamics and robust behavior of the design     

A PWM buck-boost AC chopper solving the commutation problem

A novel pulsewidth modulation buck-boost AC chopper using regenerative DC snubbers is proposed and analyzed. Compared to the previous buck-boost AC choppers, AC snubbers causing power loss are eliminated using regenerative DC snubbers. Experimental results show that the proposed scheme gives good steady-state performance of the AC chopper, which coincides with the theoretical results