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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...
This paper proposes a new topology for a pulse width modulation (PWM) rectifier which can achieves both sinusoidal input current on the ac side and ripple power decoupling on the DC side without additional switches. The AC inductor of the conventional H-bridge circuit is divided into two parts and only an auxiliary decoupling capacitor is added in the proposed circuit. Control scheme is also proposed...
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...
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,...
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...
This paper analyzes the stability issue of the Flyback converter which utilizes a second stage LC filtering circuit at its output side. The small signal models of the Flyback converter using second stage filter, in both DCM and CCM, are presented with experimental data collected to verify the theoretical analysis. Finally, guidelines for designing the second stage LC filter are derived to facilitate...
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...
In this paper, a computational method that uses only the input voltage and current to identify the impedances of multiple loads in wireless power transfer systems without any direct load measurements is proposed. The method has been practically realized in a wireless power domino-resonator system comprising 8 resonators. A good degree of accuracy has been achieved in the practical verification. Although...
Soft-switching ac-link buck-boost converters, also known as ac-link universal power converters and partial resonant ac-link converters, have received remarkable attention during the last few years. These converters, which can be configured as dc-dc, dc-ac, ac-dc, or ac-ac (single-phase or multi-phase), are compact, reliable, and expected to offer longer lifetime compared to the other types of converters...
A comparison between the open-chain (OC) and daisy-chain (DC) transformer structures for current-balancing multiple LED strings will be presented. The methodology starts with deriving a general analytical expression for describing the current distribution in both structures. The derived model is then used to study the differences in the string currents to the variations of the LED string voltages,...
Dead-times, power devices voltage drops and total output capacitance represent the most important sources of distortion of the average output voltage in voltage-fed PWM inverters. Their effect is a function of actual parameters of the drive system and of the operating conditions, and is often intolerable in many drives applications, thus requiring a proper compensation strategy. Many techniques are...
This paper presents a control method to improve the efficiency and dynamic response of wind energy control systems (WECS) that use a permanent magnet synchronous generator (PMSG) operating under a wide input and load range. An adaptive passivity-based nonlinear controller (APBC) is developed and tested. This controller is designed to overcome the limitations of conventional dq-control methods, which...
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