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This paper analyzes the behavior of a pure capacitive output filter in parallel and series-parallel resonant converters. Unlike traditional resonant voltage-and current-driven rectifiers, pure capacitive output filters present interruptions in power transfer from the transformer primary to the secondary, owing to the existence of a parallel resonant capacitor. Therefore, existing formulas for different...
“Peak Current Mode Control” (CPM) is usually implemented in analogue and brings the advantage of cycle by cycle protection, higher bandwidth rejection of input voltage disturbance or equivalently increases a converter's input impedance. “Average Current Mode Control” (ACM) allows inductor current control to a “true average” and will facilitate an accurate current limit loop or Power Factor Correction...
Common Source Inductance (CSI) is the inductance shared by the main current loop and the gate drive loop in a synchronous buck converter. Any voltage induced on CSI will change the effective gate-source voltage of the FET and has significant impacts on converter performance. This paper will explore and verify the impacts of High Side (HS) CSI on converter switch node ringing and power loss. New equations...
One of the main technical challenges of the Modular Multilevel Converter (MMC) for medium-voltage adjustable-speed motor drive applications is the large magnitude of the SubModule (SM) capacitor voltage ripple under low-speed operation. This paper proposes two new techniques to reduce the magnitude of SM capacitor voltage ripple of the MMC for motor drive applications. The paper presents a comprehensive...
This paper presents a study of a generalized multilevel asymmetric inverter based on a H-Bridge Cell with one Arm Series (CHB-as) and five switches. It is shown several asymmetrical arrangements of input source combinations that produce several equally spaced voltage levels with few components. Equations for determining the switching frequency employed in the low power processing cells are developed,...
The characteristic parameters of the micro-grids determine its transient response and the stability. The generation, the grid structure and the electric loads of all the whole micro-grids are always changing randomly due to the random load changes and the integration of large-scale batch energy, indicating that the characteristic parameters of the micro-grids also changes. A novel real-time and on-line...
It is well known that that source inductance could significantly increase turn-on and turn-off time, and therefore increase switching power loss. Also, it is well understood that switching loop inductance could reduce voltage stress during turn-on and increase voltage stress during turn-off. In this paper, a new inductive switching loss model that includes source inductance and switching loop inductance...
This paper proposes a single-phase three-level split DC-bus inverter for individual maximum power point tracking (MPPT) controls. With only eight switches and one filter inductor, the proposed system provides compact and cost-effective circuits in comparison with conventional single-phase individual MPPTs topologies. The proposed system has two split DC-buses from conventional single-phase three-level...
This paper proposes a complete maximum power point tracking (MPPT) solution for grid-connected photovoltaic (PV) systems. The proposed MPPT algorithm is a multi-stage algorithm combined with the golden section search (GSS) method and two other commonly used methods: the perturb and observe (P&O) and the incremental conductance (INC). The GSS method is used for its fast convergence time and robustness...
In this paper, an autonomous photovoltaic (PV) power generation/storage system connected to an AC nonlinear load is investigated. Depending on the load demand, the PV output power and the battery condition, five modes of operation are feasible with the changing load power. The steady-state analysis of the system for the entire operating modes is presented. Based on the concept of controllability sensitivity,...
The losses of realistic litz wires are characterized while explicitly accounting for their construction, using a procedure that computes the current-driven and magnetic-field-driven copper losses using fast numerical simulations. We present a case study that examines loss variation in one- and two-level litz wires as a function of twisting pitch, over a wide range of values and in small increments...
This paper investigates inverter time ratings and short-time electrical and thermal limitations in peak duty intermittent-load motor drives. An inverter electro-thermal model is developed and validated to complement prior motor thermal models. The inverter model is used to assess short-time capabilities of IGBT inverters. The results show that the inverter is the thermal bottleneck for short-term...
Maximum torque per ampere (MTPA) control scheme for internal permanent magnet (IPM) machine is presented in this paper. Proposed control scheme was developed based on measurement of only DC link quantities eliminating the necessity of 3-phase current feedback. The scheme employs an online search algorithm with initial condition computed from a-priory system information. Hybridization of search based...
Conventionally in wireless power transfer applications, symmetrical resonant tank (SRT) type, which employs an identical physical geometry for transmitter coil (Tx) and receiver coil (Rx), has been popular because it minimizes the leakage flux. However, for portable applications it is desirable to minimize size and weight of Rx, while Tx should provide stronger and more uniform magnetic field. Consequently,...
The unipolar gate driving method provides a low cost and simple solution for inverter system design. However, the unipolar gate driving can cause issues like ‘parasitic oscillation’ during turn-on of power switches and ‘unintended parasitic turn-on’ caused by the Miller-effect of power semiconductors. Hence the maximum value of gate resistance has to be limited. To overcome the above mentioned issues,...
A distributed power balance strategy applied for DC/DC stage in Solid State Transformer (SST) is presented in this paper. Firstly, the essence of unbalanced power issue in dc/dc stage of SST is analyzed theoretically. Then an adapted droop method is developed. The proposed control strategy can not only distributed balance the dc/dc stage output power, but eliminate the voltage drop caused by the conventional...
In conventional power system operation, droop control methods are used to facilitate load sharing among different generation sources. This method compensates for both active and reactive power imbalances by adjusting the output voltage magnitude and frequency of the generating unit. Both P-ω and Q-V droops have been used in synchronous machines for decades. Similar droop controllers were used in this...
The output voltage transient of a buck regulator during a load current step is often a key performance specification. However, many practical design approaches are based on frequency domain specifications like bandwidth and phase margin, without explicitly considering the constraints of the output filter. This paper derives an analytical expression for the peak transient output voltage due to a load...
This paper presents the small-signal modeling and controller design of an isolated Quasi-Switched-Capacitor (QSC) dc/dc converter. The converter serves as an auxiliary power supply in automotive applications, connecting the highvoltage battery and the 14 V power net. It employs a front-stage QSC dc/ac circuit with a 3:1 voltage step-down ratio, and a poststage synchronous-rectifier, current-doubler...
This paper investigates how to integrate state-trajectory control functions of LLC resonant converter within a commercial low-cost microcontroller, including Simplified Optimal Trajectory Control (SOTC) for load transient, burst mode and soft start up. Simplified calculation process is proposed for SOTC to minimize digital delay. Guideline to select a proper microcontroller is presented to limit calculation...
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