Reduced-order extended luenberger observer based sensorless vector control driven by matrix converter with nonlinearity compensation

This paper presents a new sensorless vector control system for high-performance induction motor drives fed by a matrix converter with nonlinearity compensation. The nonlinear voltage distortion that is caused by commutation delay and ON-state voltage drop in the switching devices is corrected by a new matrix converter model. A reduced-order extended Luenberger observer is employed to bring better response in the whole speed operation range, and a method to select the observer gain is presented. Experimental results are shown to illustrate the performance of the proposed system.     

Research on a novel capacitor clamped multilevel matrix converter

A new multilevel matrix converter that can be applied to medium or high voltage ac drives is presented to alleviate harmonic components in the output voltage. The proposed converter contains six flying capacitors to balance the voltage distribution of series connection bidirectional switch modules and provide middle voltage levels. Stable flying capacitors voltage must be maintained to facilitate the operation of the converter. When the converter is working, the voltage of flying capacitors can be controlled by swapping two switching modes with opposite charging current corresponding to each middle voltage levels. A simple output voltage vector synthesis method is described and utilized. The operation and commutation strategies are discussed. Simulations and experiments are carried out to validate the proposed converter. Comparisons are made between proposed converter and conventional matrix converter.     

An improved DTC-SVM method for matrix converter drives using a deadbeat scheme

In this paper, a simple direct torque control (DTC) method for sensorless matrix converter drives is proposed, which is characterized by a simple structure, minimal torque ripple and unity input power factor. Also, a good sensorless speed-control performance in the low speed operation is obtained, while maintaining constant switching frequency and fast torque dynamics. It is possible to combine the advantages of matrix converters with the advantages of the DTC strategy using space vector modulation a deadbeat algorithm in the stator flux reference frame. Experimental results are shown to illustrate the feasibility of the proposed strategy.     

低损耗软开关Boost变换器

介绍一种新的软开关Boost变换器。传统的Boost变换器在开通和关断时将产生开关损耗,因此使整个系统的效率下降。新的Boost变换器利用软开关方法增加了辅助开关管和谐振电路。这样,相比硬开关情况下,变换器减小了开关损耗。这种变换器可以应用在光伏系统、功率因子校正等装置中。详细分析电路的工作原理以及实现软开关的条件,利用Pspice9．2软件进行仿真验证。仿真结果表明,该变换器的所有开关器件都实现了软开关,从而使效率得到提高。     

A New Bidirectional Switch With Regenerative Snubber to Realize a Simple Series Connection for Matrix Converters

A new bidirectional switch and snubber circuit are proposed for medium-voltage AC/AC converters. The proposed switch can be constructed using 2-in-1 insulated-gate bipolar transistor and 2-in-1 diode modules, and can reduce the voltage stress of the switching device by series connection. The proposed snubber configuration is very simple and can regenerate absorbed energy. On the other hand, timing errors in the switching between the series-connected switches cause a voltage imbalance in the snubber circuit. Therefore, a simple method is proposed for reducing the voltage imbalance that uses one voltage sensor for each switch circuit. This proposed method controls the snubber voltages by adjusting the switch timings. Furthermore, application of the proposed switch circuit to a matrix converter is discussed and is confirmed by experiment.     

ARCP soft-switching technique in matrix converters

An alternative concept used to avoid the need for staggered switching in matrix converters is discussed. The features of the auxiliary resonant commutated pole (ARCP) soft switching technique are used to reduce the number of active switches and gate drives in comparison to conventional matrix converter technology, avoid commutation voltage spikes, and reduce switching losses. Three different ARCP matrix converters are reviewed and their operational boundaries are discussed. The ARCPMC technology is critically evaluated with respect to a potential industrial application     

A rugged soft commutated PWM inverter for AC drives

A novel DC-DC power converter for variable-speed AC power drives using the zero-voltage switching technique is described. This converter combines the advantages of soft commutated inverters and those of conventional pulsewidth modulated (PWM) inverters. In the proposed scheme, the soft commutation reduces the constraints on the switches, and the PWM enables simple and efficient regulation of the power flow. Furthermore, the zero-voltage switching technique makes operation safe, and the switching of bipolar transistors at 20 kHz is easily achieved without compromising the efficiency of the system     

A three-phase multilevel converter for high-power induction motors

A new converter topology for drives is presented in this paper: a three-phase multilevel converter with separately regulated DC power supplies. The DC voltages are provided by medium-frequency DC-DC converters. The applications for the converter are especially high-power traction systems, where the voltage applied to the induction motor is bigger than 1 kV. The motor current is of a very high quality, compared to a classical three-phase converter. This allows keeping the switching frequency low by using phase-shifted pulsewidth modulation (PWM) carriers. Different modulation methods have been developed and simulated. Experimental tests have been made on a 12 kW prototype     

Module-type switching rectifier for cathodic protection of underground and maritime metallic structures

Cathodic protection is widely used to prevent corrosion of steel materials buried underground and in seawater. As a rectifier for cathodic protection, the conventional phase-controlled rectifiers with 50- or 60-Hz isolation transformers have been used so far in spite of such shortcomings as large volume, heavy weight, and poor power factor. In order to overcome such disadvantages, this paper proposes a new module-type switching rectifier for cathodic protection, which is composed of two parts, namely, ac/dc converter and module-type dc/dc converter. The ac/dc converter is a single-phase insulated gate bipolar transistor pulsewidth-modulation rectifier, thus resulting in almost unity power factor and controlled dc output voltage. The module-type dc/dc converter operates under zero-voltage switching/zero-current switching condition to permit high-frequency switching operation. It enables the use of a high-frequency transformer for electrical isolation, thus reducing volume and weight of the overall system and improving system efficiency. It is anticipated that the proposed rectifier techniques will apply to the similar technical areas such as multiple-module power supply systems and modular converter-fed dc motor drives.     

Control of Single-Phase-to-Three-Phase AC/DC/AC PWM Converters for Induction Motor Drives

This paper proposes a novel control scheme of single-phase-to-three-phase pulsewidth-modulation (PWM) converters for low-power three-phase induction motor drives, where a single-phase half-bridge PWM rectifier and a two-leg inverter are used. With this converter topology, the number of switching devices is reduced to six from ten in the case of full-bridge rectifier and three-leg inverter systems. In addition, the source voltage sensor is eliminated with a state observer, which controls the deviation between the model current and the system current to be zero. A simple scalar voltage modulation method is used for a two-leg inverter, and a new technique to eliminate the effect of the dc-link voltage ripple on the inverter output current is proposed. Although the converter topology itself is of lower cost than the conventional one, it retains the same functions such as sinusoidal input current, unity power factor, dc-link voltage control, bidirectional power flow, and variable-voltage and variable-frequency output voltage. The experimental results for the V/f control of 3-hp induction motor drives controlled by a digital signal processor TMS320C31 chip have verified the effectiveness of the proposed scheme     

零电流开关大功率DC/DC双全桥变换器设计

提出了一种基于双全桥结构的单向零电流开关大功率（兆瓦级）DC/DC变换器,该变换器通过采用两个全桥变换器来实现零电流开关,实现了较低的功率损耗和输出滤波电感。为了验证提出的变换器在大功率应用中的有效性,构建了小型样机并在大功率直流电网进行了实际测试。实验证明,相比传统的两种单向大功率全桥变换器,提出变换器所需的滤波电感和半导体器件的功率损耗均较少,分别仅为1.72mH和924.5kW。     

Power electronic converters for motion control

The historical development of power electronic converters to control electrical machines is traced up to the present state of the technology. The fundamental possibilities to control average power in a switching mode are considered and the concepts switching function, converter topology and converter structure defined. A systematic approach to developing more complicated topologies and structures for singular and composite converters is discussed and application to motion control systems given. A functional classification of motion control converters is also related to the switching nature of the power processing, illustrating the fundamental dilemma of this kind of highly efficient power control. The different control possibilities of using power electronic converters with electrical machines in motion control applications (DC drives, AC drives) are reviewed systematically. The paper does not attempt to compile a comprehensive list of all possible converter circuits and variations but focusses on generic issues and technologies. The switching technology in converters and its limitations is related to snubberless, snubbed, and resonant transition-type operation, with reference also to switch drive and converter protection technology. Some future generic possibilities related to electromagnetic integration of switching converters are discussed, also in relation to a motion control application     

Sensorless DTC-SVM for Induction Motor Driven by a Matrix Converter Using a Parameter Estimation Strategy

This paper presents a new direct torque controlled space vector modulated method to improve the sensorless performance of matrix converter drives using a parameter estimation scheme. The flux and torque error are geometrically combined in a new flux leakage vector to make a stator command voltage vector in a deadbeat manner. A new sensorless method of estimating the rotor speed, flux, stator resistance, and rotor resistance is derived and verified with experimental results. Common terms in the error dynamics are utilized to find a simpler error model involving some auxiliary variables. Using this error model, the state estimation problem is converted into a parameter estimation problem assuming the rotor speed is constant. The proposed adaptive schemes are determined so that the whole system is stable in the sense of Lyapunov. The effectiveness of the proposed algorithm is verified by experiments.     

Short term braking capability during power interruptions for integrated matrix converter-motor drives

The new trend in adjustable speed drives (ASD) is to integrate the inverter and the motor into a single unit in order to reduce the production cost, the commissioning time, and the physical size of the equipment. This last issue becomes more important, making the matrix converter topology more attractive. Sinusoidal input currents and bidirectional power flow are other advantages of the matrix converter but it is less immune to power grid disturbances compared to a standard ASD. In hoisting applications, short-term braking capability during a power outage is needed until the mechanical brake engages or to perform more effective a combined braking. This paper proposes a new method to provide short-term braking capability during a power outage for matrix converters. A braking chopper is needed in the clamp circuit, which allows for a drastically reduction of the capacitor size. The power flow in the clamp circuit may be reduced by increasing the harmonic content in the motor currents, which causes higher motor losses. Experiments prove the validity of the proposed method.     

Predictive Approach to Increase Efficiency and Reduce Switching Losses on Matrix Converters

The matrix converter stands as an alternative in power conversion. It has no energy storage devices, performing the energy conversion by directly connecting input with output phases through bidirectional switches based on power semiconductors, allowing high-frequency operation. For this reason, it is known as the all-silicon power converter, featuring reduced size and weight. Forced commutations of the high number of semiconductors cause switching losses that reduce the efficiency of the system and imply the use of large heat sinks. This paper presents a novel method to reduce switching losses based on predictive control. The idea is to predict switching losses for every valid switching state of the converter, if applied during the next sampling time, and then, select the optimum state based on an evaluation criterion. The proposed strategy was experimentally tested on an 18-kVA matrix converter driving an 11-kW induction machine, reducing energy losses and increasing efficiency up to 3% compared to the basic strategy. As a consequence, the converter misuses less energy and requires smaller heat sinks.     

Reverse matrix converter control method for PMSM drives using DPC

This paper proposes a control method for a reverse matrix converter (RMC) that drives a three-phase permanent magnet synchronous motor (PMSM). In this proposed method, direct power control (DPC) is used to control the voltage source rectifier of the RMC. The RMC is an indirect matrix converter operating in the boost mode, in which the power-flow directions of the input and output are switched. It has a minimum voltage transfer ratio of 1/0.866 in a linear-modulation region. In this paper, a control method that uses DPC as an additional control method is proposed in order to control the RMC driving a PMSM in the output stage. Simulations and experimental results verify the effectiveness of the proposed control method.     

Experimental evaluation of ride-through capabilities for a matrixconverter under short power interruptions

The matrix converters, which are direct power electronic converters, are able to provide important benefits such as bidirectional power flow, sinusoidal input currents with adjustable displacement angle, and a great potential for size reduction. Still, two major disadvantages exist: a lower than unity voltage transfer ratio and high sensitivity to power grid disturbances. Many solutions to provide continuous operation of adjustable speed drives (ASDs) during power grid disturbances have been proposed, but they are all applied to DC-link ASD. In this paper, a new solution to provide limited ride-through operation is presented with a matrix converter using a scalar controlled induction motor for a duration of hundreds of milliseconds, without any hardware modification. During the ride-through operation, the drive is not able to develop torque or to control the motor flux. By recovering the necessary power to feed the control hardware of the matrix converter, it is able to keep the ASD operating. When normal grid conditions are reestablished, the matrix converter is able to accelerate the motor from nonzero speed and flux by initializing the modulator with the estimated frequency and the initial angle of the reference output voltage vector. The maximum duration of the ride-through operation depends on the initial motor flux, speed level, rotor time constant, load torque, and inertia. This method is verified on a laboratory setup with a matrix converter     

Continuously motor-synchronized ride-through capability formatrix-converter adjustable-speed drives

The ride-through capability of adjustable-speed drives has become an important issue due to its direct impact on production and revenue losses. Moreover, different industrial surveys have shown that voltage sags are the main cause of converter tripping. Disturbances such as swells, distortion, and impulses were found far less common and did not cause any tripping nor production losses. Matrix-converter (MC) drives are also prone to voltage sags, furthermore the lack of the DC-link capacitor renders them somehow more vulnerable. This paper presents a ride-through strategy for MC adjustable-speed drives. The strategy is based on the reduced speed/load approach for conventional drives and is capable of enforcing constant volts/hertz operation regardless of the supply voltage conditions by first regulating the modulation index of the matrix converter, which counteracts the supply voltage drop, and second by reducing the speed reference if required. This reduction seeks to maintain the maximum torque capability of the drive and not to reduce the motor load as in conventional drives. Hence, the proposed strategy is suitable for both variable and constant torque loads. Moreover, the converter never loses synchronization with the motor, so it is capable of immediate acceleration to its former speed after the disturbance disappears. The proposed strategy was experimentally verified under typical industry disturbances using a TMS320C32 DSP based system. Particularly, three-phase and single-phase sags varying from 10% to 60% were tested. Results obtained showed the effectiveness of the proposed strategy for MC adjustable-speed drives     

A Three-Level Resonant Single-Stage Power Factor Correction Converter: Analysis, Design, and Implementation

This paper presents a new single-stage power factor correction ac/dc converter based on a three-level half-bridge resonant converter topology. The proposed circuit integrates the operation of the boost power factor preregulator and the three-level resonant dc/dc converter. A variable-frequency asymmetrical pulsewidth modulation controller is proposed for this converter. This control technique is based on two integrated control loops: the output voltage is regulated by controlling the switching frequency of the resonant converter, whereas the dc-bus voltage and input current are regulated by means of duty cycle control of the boost part of the converter. This provides a regulated output voltage and a nearly constant dc-bus voltage regardless of the loading condition; this, in turn, allows using smaller switches and consequently having a lower on resistance helping to reduce conduction losses. Zero-voltage switching is also achieved for a wide range of loading and input voltage. The resulting circuit, therefore, has high conversion efficiency making it suitable for high-power wide-input-voltage-range applications. The effectiveness of this method is verified on a 2.3-kW 48-V converter with input voltage (90–265 Vrms).      

Nonisolation Soft-Switching Buck Converter With Tapped-Inductor for Wide-Input Extreme Step-Down Applications

In this paper, a new zero-voltage switching (ZVS) buck converter with a tapped inductor (TI) is proposed. This converter improves the conventional tapped inductor critical conduction mode buck converters that have the ZVS operation range determined by the TI turn ratios. It includes another soft switching range extension method, the current injection method, which gives an additional design freedom for the selection of the turn-ratios and enables the optimal design of the winding ratio of the TI so that the efficiency may be maximized. This soft-switching buck converter is suitable for wide input range step-down applications. The principle of the proposed scheme, analysis of the operation, and design guidelines are included. Experimental results of the 100-W prototype dc-dc converter are given for hardware verification also. Finally, based on the proposed soft-switching technique, a new soft-switching topology family is derived.