This paper presents a new bridgeless buck-boost power factor corrector with the use of the active virtual ground technique, which is named as the Manitoba Rectifier. The proposed topology can convert the grid ac voltage into a wide range of voltage outputs within a single-stage circuit. It is in a bridgeless structure and simple in design. During the operation, an LC filter is generated at the system input, where continuous grid current is guaranteed in a buck-boost characteristic topology. In addition, the filter capacitor helps to clamp the voltage ripple between the grid and the output bus terminal. Both leakage current and common mode noise are kept in a relatively small value. Thus, a single-stage and low common-mode buck-boost converter system is built. The proposed topology is successfully implemented on an 800 W prototype, and the performance is experimentally verified, which shows good agreement with the theoretical findings.

In this paper, a module-based plug-n-play (PnP) dc microgrid is introduced to help rural electrification. It provides a bottom-up way to form a microgrid (MG) with multilayer expandability and Plug-n-Play feature. The module-based MG overcomes the drawback of conventional MG that requires central design and implementation which leads to high upfront cost and long lead time. It provides an organic way to form a MG that allows user to scale up the system as their demands growing, and fully utilize the existing resources. The proposed MG module is expandable on different layers that can meet requirements of customers with different power consumption requirements. Each module, which contains PV generation and energy storage, can work as a standalone solar home system. Multiple modules can be connected as a group to scale up the local power supply. Groups can be interconnected through a public bus with gateway converter modules to form a community network, which can supply public usages and enables power exchange in a community range with relatively high distribution efficiency. The control of proposed MG is in a fully decentralized manner, that central control and communication network can be omitted, which makes the system more user-friendly and highly robust. Detailed design, analysis and implementation of the proposed PnP MG is provided in this paper. Simulation and experimental results have been provided to verify the concept and analytical study.

A new E?-shape coupled inductor structure and its magnetic circuit models are presented. The proposed E?-shape coupled inductor structure retains the advantages of high power density and tackles the drawback of high air-gap fringing flux losses in conventional E-shape coupled inductor structure. Besides, the proposed E-shape structure gives the advantages of shorter winding length and more uniform thermal distribution compared with the conventional E-shape structure. The proposed E-shape structure and its magnetic models are successfully simulated by ANSYS and Maxwell 2-D, and implemented to apply to interleaving bidirectional dc/dc converters. The simulated and experimental results show that the proposed E?-shape structure of coupled inductors is superior to the same volume E?-shape structure of coupled inductors in terms of temperature, inductance, losses, inductor ripple currents, and efficiencies. The theoretical prediction and experimental results are in good agreement.

An efficient single-phase Transformerless grid-connected voltage source inverter topology by using the proposed active virtual ground (AVG) technique is presented. With the AVG, the conventional output L filter can be reconfigured to LCL structure without adding additional inductor. High-frequency differential mode current ripple can be significantly suppressed comparing to the available single-phase grid-connected inverter topologies. Additionally, strong attenuation to the high-frequency common-mode current is achieved. It is particularly important for some applications such as photovoltaic and motor drives. High efficiency can be achieved due to fewer components involved in the conduction loss. Cost of the magnetic device can be reduced since the required inductance of the filter becomes smaller. Performance of the proposed inverter has been evaluated analytically. Experimental verification is performed on a 1-kW, 400-V input, and 110-V/60-Hz output prototype.

The paper presents a new bridgeless power factor correction (PFC) topology, using a recently proposed controllable LCL filter, namely active virtual ground to achieve efficient power conversion, and high-frequency common mode voltage (CM) reduction. The proposed PFC circuit consists of high-frequency semiconductors for shaping inductor current and low-frequency semiconductors to form two different LCL structures for different conditions. This reduces grid differential mode current ripple or inductance. Besides, the PFC CM voltage, a main problem of bridgeless PFCs, is significantly reduced, since the capacitor in the LCL filter clamps the voltage between the grid and the converter ground. The performance of the proposed PFC is experimentally verified. The results show that the proposed PFC guarantees sinusoidal input current, low high-frequency common-mode voltage noise, and has a good agreement with the theoretical findings.

An electrical transient model (ETM) of insulated-gate bipolar transistor (IGBT)-diode switching cell is developed by coupling a temperature-dependent IGBT model with power loss model. The nonlinear behavior of IGBT and the reverse recovery characteristic of the diode are considered in this model to simulate the transient switching waveforms. Based on the transient waveforms of ETM under various operating conditions, the power loss estimation method (PLEM) for IGBT is developed. In addition to traditional modeling techniques that only uses ideal switch, this paper uses the model to replicate the power loss behaviors of semiconductor devices in circuit simulation by looking up tables. The proposed ETM is simulated in PSCAD/EMTDC with nanosecond time step, whereas the overall system application can be simulated with conventional time step in range of microsecond. By this way, the model can promise reasonable accuracy as well as an acceptable fast solving speed. The proposed ETM and PLEM have been implemented in PSCAD/EMTDC simulator and validated by experimental results using a double pulse test bench and boost converter test platform.