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A recently proposed third harmonic injection rectifier (two half-bridge legs) - serving as optional solution for passive three-phase diode bridge systems with LC output filter - is characterized by unity power factor (λ ≈ 1) and low harmonic input currents (THD < 5%). The rectifier at hand, furthermore sticks out of the crowd due to a very low number of active and passive switches compared to similar...
This paper presents a neutral point deviation compensating control algorithm applied to a 3-level NPC converter. The neutral point deviation is analyzed with a focus on the current flowing out of or into the neutral point of the dc-link. Based on the zero sequence components of the reference voltages, this paper analyzes the neutral point deviation and balancing control for 3-level NPC converter....
A complete control system of smart microgrid is proposed in this paper, in order to realize the smooth mode transfer of the grid-connected mode (GTM) and islanding mode (ILM). In the system, every DG unit will work as the voltage source and use the same control method of output voltage, whatever in GTM or ILM. The only difference of GTM and ILM is how to regulate of the reference voltage of the voltage...
This paper proposes synchronization strategies for cascaded H-Bridge multi level inverter (CHBMLI) topologies with carrier based sinusoidal pulse width modulation (PWM) techniques. It is presented how synchronous carriers are generated in desired phase and frequency from the instantaneous voltage references to maintain 3-Φ, half wave and quarter wave symmetries among inverter pole voltage outputs...
In this paper, design and implementation of a sinusoidal flux controller has been proposed for a core loss tester for eliminating the higher order harmonics from the flux passing through the core. The core loss test is performed with a toroidal transformer that consists of a main and sense windings wound on a toroidal core. The flux through the core is calculated with the numerical integration of...
Concerning cost, volume, and efficiency, Adjustable Speed Drive (ASD) systems are commonly employed with diode rectifiers or Silicon Controlled Rectifiers (SCR) as the front-ends (i.e., ac-dc converters). Apart from low cost, small volume, and high reliability, harmonic currents are significantly produced at the grid side by the rectification apparatus (i.e., diode rectifiers or SCR). As a simple...
Adjustable Speed Drives (ASDs) based on double-stage conversion systems may inject interharmonics distortion into the grid, other than the well-known characteristic harmonic components. The problems created by interharmonics make it necessary to find their precise sources, and, to adopt an appropriate strategy for minimizing their effects. This paper investigates the ASD s input current interharmonic...
This paper presents an active islanding detection method which has zero non-detection zone. This method is the advanced version of the conventional slip mode frequency shift islanding detection method (SMS IDM). In this method the parameters of SMS IDM change based on the local load impedance value. The parameters value are calibrated periodically by measuring the impedance of the local load. The...
In high power conversion, low device switching frequency operation is preferred in order to satisfy the thermal constraints of the semiconductor devices and also to improve efficiency. However, low device switching frequency operation leads to higher total harmonic distortion (THD) of the converter output currents. Synchronous optimal pulse-width modulation (SOP) technique is an emerging low device...
This paper presents a new control scheme for a single-phase PWM rectifier with Auxiliary Current Injection Circuit (ACIC) to improve the load transient response and DC bus voltage controller bandwidth. The PWM rectifier and ACIC are controlled to mitigate the 2nd harmonic ripple in the DC bus under steady-state as well as the peak undershoot and overshoot during load transients. Analytical equations...
Critical conduction mode(CRM) Buck power factor correction(PFC) with peak current-controlled of currentmode control, its traditional control is constant on-time control, the switching frequency varies with the input voltage and load variations, and a relatively large frequency range, lead to a large of switching loss. This paper proposes a variable on-time control strategy for a CRM Buck PFC converter...
Industrial and academic interest on multiphase electric machines have been steadily increasing due to the advantages they provide compared to their three phase counterparts. They offer higher efficiency and better fault tolerance. The power is distributed across a larger number of machine phases and inverter legs, which allows the use of semiconductor devices with lower ratings. These advantages are...
This paper proposes a general and an improved methodology for the design of the passive elements of Active Regenerative Rectifiers (ARR). The proposed strategy for the L-filter is based on the current area error in the time domain and on the high order current harmonics in the frequency domain. This strategy is independent of the type of control technique and it can be implemented for different modulation...
Current fed multilevel converters have several advantages in terms of high power capability, transformer less operation, short circuit protection and excellent quality of waveforms. For high power applications, these converters are required to be operated under low device switching frequency to necessitate thermal constraints of the semiconductor devices. However, the converter output currents under...
There has been a growing demand of using multi-function inverters for grid-connected systems applied to nonconventional energy sources, such as solar, wind and so on. In addition to power quality conditioning, the inverter can also be used for bidirectional active power exchange with a three-phase four-wire grid. Therefore, the inverter acts as a multi-function compensator. The functions of the proposed...
Ac transmission line emulator is the bridge to interconnect ac systems to fulfill the grid emulation function, where all the emulator elements such as generators, loads and lines are implemented by universal three-phase voltage source converters. In this paper, three design issues are addressed. First, the impact of ac voltage switching noise on the performance of a transmission line emulator in terms...
In stand-alone brushless doubly fed generator (BDFG) based shaft power generation system, the output voltage of BDFG is strong influenced by the filter of load side converter (LSC) because of the coupling caused by the stator power winding leakage inductance. In order to eliminate the harmonic of the voltage, the LC-L filter based on the leakage inductance is put forward in this paper. The relationship...
This paper analyzes the inverter nonlinearity effect resulting in issues such as narrow pulses and the even order harmonics in three-level T-type inverters. These issues make the compensation of the inverter nonlinearity be difficult. Based on the analysis of the output voltage distortion, carrier-based PWM methods to avoid these issues and to balance dc-link voltages simultaneously are proposed using...
In single-phase AC onboard chargers for electrified vehicles, second-order harmonic current and corresponding ripple voltage exist on the DC bus. The low-frequency harmonic current is normally filtered using a bulk capacitor or an additional active filter (AF) circuit. This presents an obstacle for improving the power density as well as reducing the cost. In this paper, a dual active bridge (DAB)-based...
Due to relatively low cost and flexible performance, Dynamic Capacitor (D-CAP) is often designed to implement dynamic reactive power compensation, whose output current might distort under the effects of background harmonic voltage from the grid or non-ideal PWM mode caused by non-linear switch characteristics. This paper presents a reactive power compensation control strategy with waveform quality...
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