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This paper presents a mid-voltage experimental voltage generator used for the testing mainly of distribution power equipment, high-power drives and renewable power generation. It utilizes thyristor-controlled zigzag transformer as its primary circuit. Based on the analysis of the operation mechanism, the voltage equations are derived and control strategy is proposed. This power electronic zigzag transformer...
This paper presents a method to shed off the least important loads in a microgrid operated at constant frequency under the contingency of inadequate power generation. Different from conventional frequency deviation based load shedding, this paper discusses in detail how to shed off load based on the voltage deviation. The key issue is to differentiate whether the voltage deviation is due to sudden...
According to the requirement of the power factor and the dynamic performance of the asynchronous machine tool field, an asynchronous motor inverter with active power factor correction is proposed. The proposed inverter is a 3kW asynchronous motor drive control platform. At first, the proposed single phase converter with APFC is realized by using the MATLAB/SIMULINK. Then, the boost APFC is designed...
This paper presents a new speed control system for a flux-modulated permanent-magnet (FMPM) in-wheel motor. It is based on deadbeat-direct torque and flux control (DB-DTFC) to reduce the torque ripple and improve the steady performance compared with conventional SVPWM-DTC system. DB-DTFC calculates the control input of next control period so that a new stator current observer is proposed to predict...
In this paper, a novel supply voltage harmonic mitigation method using a simple DVR without harmonic detection is proposed. In contrast to the conventional DVRs control methods, the proposed method realizes two independent control objectives at fundamental and harmonic frequencies without couplings, with the adoption of the proposed voltage controller with two independent inputs focusing on different...
A DC bus voltage ripple suppression method based on super-capacitor (SC) was proposed under unbalanced load. Firstly, the influence of unbalanced load on DC microgrid was analyzed. And then, depending on the mathematical model of the SC compensation device, current control strategy of the SC was designed using the sliding mode control (SMC) to precisely track the pulsating current. Furthermore, parameters...
In this paper, a novel three-port converter(TPC) for stand-alone photovoltaic(PV) power system application is proposed, and also presents the control strategy and power management of this converter. This converter uses three power switches, two inductors and switched capacitor structure to obtain a higher voltage gain and reduce the voltage stress of the power switches. The control for the converter...
The performance of reactive power sharing in an islanded microgrid is significantly affected by feeder impedance, mismatch parameters and unbalanced local load. To reduce the negative impact of mismatched link impedance on reactive power sharing, the adaptive virtual impedance strategy for voltage compensation is proposed with paralleled inverters in an islanded mode. The on-line adaptive control...
This paper is concerned with the process of current commutation and overvoltage protection in matrix converters. The mechanisms involved in the commutation process and clamp circuit are described and simulation waveforms are presented. A four-step semi-soft commutation strategy is described that this technique relies on knowledge of the output current direction and the ability to control the direction...
Traditional PI controllers can have poor regulation performance due to steady state errors when tracking sinusoidal signals. Hence synchronous PI controllers are often used, although this controller requires reference frame transformations. In this paper, a modified PI controller, which uses current feedforward, is developed to control the output currents of a matrix converter. The controller is implemented...
The direct matrix converter has been regarded as a promising AC/AC conversion topology and it is being researched. Motor drives are one of the main potential applications of the matrix converter. This paper carries forward the application of matrix converters in AC motor drives using direct torque control (DTC). In the common DTC scheme for the matrix converter, two vectors with the maximum amplitudes...
According to the traditional control of three-phase inverter, basing on the transient mathematical model of second order of virtual synchronous generator, the three loops control of power-voltage-current with virtual synchronous generator (VSG) by using the feedback of capacitance's voltage and current was built. And the proportional and integral control was applied in the loop of voltage to ensure...
In this paper, a novel smart fast charging system is proposed to meet various types of charging needs. Based on the modular design principle, the system can be flexibly configured according to the number of electric vehicles and charging power needs, and the configuration is carried out in the use of the charging station. A power distribution unit based on a power electronic device rather than a switch...
A switching circuit system based on FPGA is designed and implemented in this paper to provide high- frequency adjustable-phase voltages for the ultrasonic motor. For the existing drive systems of the ultrasonic motor, the bus voltage is usually 12 V DC or 24 V DC supporting by an external adapter, the driving voltages of the ultrasonic motor, however, are required to be boosted yet. Then, the step-up...
To improve the dynamic performance and the anti-disturbance capability of the photovoltaic energy storage system, a control strategy of the bidirectional DC-DC converter based on Linear Active Disturbance Rejection Control (LADRC) is proposed in this paper. Firstly, the mathematical model of the bidirectional DC-DC converter is established. And then, the double closed-loop control strategy based on...
With more renewable resources integrated to the grid, energy storage is expected to rise to the challenge of the grid caused by the characteristics of the intermittent renewable sources. This paper presents an innovative battery energy storage system (BESS) combined with the decoupled PQ control and adaptive capacity-based droop control for both grid-connected operation and stand-alone operation....
Permanent Magnet Synchronous Motors (PMSMs) operating among wide speed range needs optimal flux-weakening method to reach to higher speed level. For motors whose critical point locates within the current limit circle, two different flux-weakening algorithms are discussed comparatively in this paper. One is the traditional feedback flux-weakening control strategy, the other is a revised feedback flux-weakening...
Model predictive direct power control (MPDPC) has been widely noticed in the field of doubly fed induction generator (DFIG) control. The optimal vector is selected based on the principle of power error minimization. However, conventional MPDPC will produce high power ripples and large current distortion under unbalanced grid voltage condition. To achieve sinusoidal stator currents and/or constant...
This paper presents a novel control strategy to reduce the DC-link voltage ripple for electrolytic capacitor-less PMSM drive system. By injecting the 3rd harmonic current into the driver system, the instantaneous power balance between the grid output power and the motor output power is achieved, so the DC-link voltage ripple is reduced obviously. For further improving the PMSM performance under DC-link...
Model predictive current control (MPCC) is a powerful control strategy for the control of three-phase power converters. Conventional MPCC achieves good steady state performance and quick dynamic response by selecting the optimal voltage vector. However, this method is highly dependent on the accuracy of the model and parameters, which means that the steady state performance will deteriorate when the...
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