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High bandwidth Linear Regulator can be applied in high bandwidth Tracking Power Supply or high bandwidth Current Source. This paper proposes a 3-Port model for Linear Regulator to predict and improve its performance in those applications. The performance includes Tracking Bandwidth and Power Supply Rejection Ratio for high bandwidth Linear Tracking Power Supply as well as Slew-Rate and Overshoot for...
Photovoltaic (PV) energy has been widely interested today because it is clean and endless energy without causing pollution. To produce electricity from solar energy, it would be required an inverter to convert the direct current into alternating current. The inverter is the cause of problems that affect the stability of the power system because it is a switching device served to adjust the frequency...
Lighting system is an important part in everyday life. Today, lighting technology has been developing in many aspects. Technology such as Light Emitting Diode (LED) luminaire has been applied to indoor lighting system to replace conventional luminaire. LED lamps have many advantages such as less energy consumption, long life cycle and environmental friendly issue due to without toxic component. However,...
A compact 2-terminal, series-pass active damping circuit utilizing semiconductor device is proposed. It is implemented with linearly-operated device such as MOSFET using current feedback control at very low dropout voltage. The damping device features a simple internal structure and is connected in series with a generic switching mode power supply (SMPS). It can damp unwanted oscillation due to the...
In high-frequency (HF) pulsating voltage injection-based sensor-less surface-mounted permanent magnet synchronous motor (SPMSM) control, inverter nonlinearities and motor parameter asymmetries lead to harmonic errors in the estimated position. To eliminate these errors, the second-order generalized integrator (SOGI) is applied. An enhanced position observer with a selective harmonic error eliminator...
Magnetic components are very important part in the power electronics system. Given weight and constrain space in the power converter, high power density converter is increasely required. In the whole system, half of the weight are the magnetic components. For the grid-connected system, the LCL filter is a necessary part to suppress the noise due to the high switching frequency transistor appeared...
This paper presents the development of a position sensorless controlled synchronous reluctance motor (SynRM) drive. First, the basic vector controlled SynRM drive is established, including power circuit, sensing and commutation schemes. Then the high-frequency injection (HFI) based rotor position estimator is developed to yield the rotor position for making the vector control. After comprehending...
DC power distribution gains popularity in future residential, renewable energy, transportation and data centers. Such dc system can be connected to ac system through bidirectional interface converter. Compared with isolated converters, transformerless solutions have the advantages of higher power density, efficiency, and lower cost. One concern about the non-isolated connection is the coupled common-mode...
Interior permanent magnet synchronous motors often work under flux weakening state in electrical vehicles for higher speed but faults, such as overcurrent and overvoltage, might occur during that process, after which the power transistors are closed immediately and the battery packs are charged through three-phase uncontrolled rectifier composed of six fly-wheel diodes. It is called uncontrolled generation...
This paper proposes a controller design to compensate the current harmonics from the nonlinear load when a grid-connected inverter operates as an active power filter. When the LCL filter is installed at the output of inverter, the controller should be designed differently depending on the location of the nonlinear load. As this nonlinear load is connected to the grid before or after the grid side...
The nonlinear loads in microgrid not only distort the voltage but also degrade the harmonic power distribution in a conventional droop-controlled microgrid. This paper starts with analyzing the trade-off between voltage total harmonic distortion (VTHD) and harmonic sharing effectiveness. A multi-framed droop controller is proposed to improve the harmonic power sharing without deteriorating VTHD by...
This study proposes an enhanced current control strategy to eliminate DC and harmonic current at the output current of three-phase grid-connected inverters caused by DC offset and scaling error in grid voltage measurement. The proposed current controller designed in the stationary (α-β) reference frame is developed with a proportional integral (PI) plus three resonant controllers where the resonant...
In this work, load current in a multi-unit microgrid is decomposed into components. These components reflect the nature of total connected load at the point of common coupling (PCC) with the utility grid. Each unit (composed of distributed energy resources (DER), interfacing converter, and filtering elements), contributes to the total current fed by the microgrid. The current supplied by a unit is...
This paper presents a grid-connected bi-directional modular multilevel converter (MMC) with division-summation (D-Σ) digital control to achieve power injection and rectification functions. The D-Σ digital control is adopted to track current reference, regulate dc-bus voltage and cell voltage, and balance the upper and lower dc-bus voltages. It can accommodate wide filter inductance variation and take...
This study examines the P+ multi resonant based voltage control for the voltage harmonics compensation under the islanded mode of a microgrid. In islanded mode, the inverter is defined as a voltage source to supply the full local load demand without a connection to the grid. On the other hand, the output voltage waveform is distorted by the negative and zero sequence and current harmonics due to the...
With the requirement of high power density converters, the volume of the EMI filter needs to shrink as much as possible. This paper studies a super small volume and high insertion loss active EMI filter. Firstly, a high current and high efficient AC-DC converter is analyzed. The CM interference is predicted precisely. Secondly, traditional active EMI filters are analyzed by calculating. A high performance...
This study investigates the cell voltages and arm currents in double-star modular multilevel converters (DSMMCs) based on power balance and current tracking control law. DSMMCs have been widely applied to static synchronous compensators, high-voltage direct-current transmission, back-to-back power transfer systems, wind/solar power generation and battery storage systems. The size of capacitors in...
The Renewable power generations are sometimes located in remote area from the load centers and connected through the long transmission lines. In such case, the AC voltage likely varies along with the renewable power variation. The static Var compensator (SVC) is required to stabilize the AC voltage for stable power transmission [1]. In long transmission lines, the geomagnetic disturbance possibly...
This study presents design of D-Σ digital controlled hybrid-frequency inverters with LCL filter for grid-connected applications. Hybrid-frequency inverters consist of inverters with different frequencies and power ratings connected in parallel. The lower frequency inverter has higher power rating, while the higher frequency inverter has lower one. The inverters are controlled to cancel out low-frequency...
In this paper, a simple THD improving method for a CCM boost PFC converter is proposed. Due to its small inductor current ripple, small conduction loss, and small input filter, the conventional CCM boost PFC converter is widely used in medium to high power applications. But, although it is designed to operate with CCM, it starts to operate with DCM in light load condition. This mode is called the...
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