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An integrated synchronous buck converter with a high resolution dead time control for input voltages up to 48V and 10MHz switching frequency is presented. The benefit of an enhanced dead time control at light loads to enable zero voltage switching at both the high-side and low-side switch at low output load is studied. This way, compact multi-MHz DCDC converters can be implemented at high efficiency...
The newly proposed FREEDM-Pair is an ideal and economical solution to address high cost issue in high power SiC power devices. The FREEDM-Pair, in which a Si IGBT and a SiC JFET are connected in parallel, combines the advantages of SiC JFET's low switching losses and Si IGBT's superior forward conduction characteristics. One issue of the JFET based FREEDM-Pair is the incompatible gate drive voltage...
This paper presents a gate driver integrated circuit (IC) for Silicon Carbide (SiC) devices to fully utilize their high switching speed capabilities in a phase-leg configuration. Based upon the intrinsic properties prevalent in SiC devices, gate assist circuitry is integrated into a gate driver IC to control the gate voltages seen by both devices in a phase-leg during different switching transients...
LLC resonant converters have gained popularity in a variety of applications due to their natural ability to provide soft switching conditions. Although LLC features good efficiency, conductive losses in the output rectifier remains a barrier to achieve enhanced efficiency, specially for high output current applications. This paper introduces a new strategy referred to as Coordinate Modulation, which...
Repetitive control strategies have been commonly applied in pulse-width modulated (PWM) inverters for many industrial applications. The phase delay in the overall control system, e.g. the delay caused by the digital duty cycle calculation, PWM generation and the repetitive controller, has to be compensated by elaborately designed phase lead filters in order to prevent control performance deterioration...
An isolated dc-dc series-resonant converter that is controlled by a combination of variable-frequency and secondary-side-switch delay-time control is employed as the output stage of the on-board charger module (OBCM) that operates with a wide battery-voltage range. The delay-time control which is implemented by the modulation of secondary-side switches is used to assist the conventional variable-switching-frequency...
A new method is implemented in designing of self-oscillating loop for driving piezoelectric transformers. The implemented method is based on combining both analog and digital control systems. Digitized delay, or digitized phase shift through the self-oscillating loop results in a very precise frequency control and ensures an optimum operation of the piezoelectric transformer in terms of voltage gain...
In this paper, the performance of different interleaving control methods for gallium-nitride (GaN) devices based MHz critical conduction mode (CRM) totem-pole power factor correction (PFC) circuit is compared. Both closed-loop interleaving and open-loop interleaving are good for low frequency CRM PFC; but for MHz very high frequency CRM PFC with microcontroller (MCU) implementation, open-loop interleaving...
For the grid-connected voltage source inverters, the feedforward scheme of grid voltage is commonly adopted to mitigate the current distortion caused by grid background voltages harmonics. This paper investigates the grid-voltage-feedforward active damping for grid connected inverter with LCL filter. It reveals that proportional feedforward control can not only fulfill the mitigation of grid disturbance,...
This paper analyzes first the stability of single-loop digital voltage control scheme for the LC-filtered voltage source inverters. It turns out that the phase lag, caused by the time delay of digital control system and by the use of integral controller, can stabilize the voltage loop without damping of LC-filter resonance. The stability regions are then identified with alternative voltage controller...
Insulated gate bipolar transistors (IGBTs) are usually connected in series to satisfy the requirements of high-power and high-voltage in power electronics applications. However, due to the parameter deviations of the series-connected IGBTs, it is difficult to ensure an equal voltage sharing between them during both transient and steady-state operations. This paper proposed a novel active gate drive...
Grid synchronization has always been an important challenge for three-phase grid-connected converters under unbalanced and distorted grid conditions. Moreover, how to quickly and accurately extract multiple harmonic sequence information is essential for control systems. In this paper, a three-phase multiple harmonic sequence detection method is proposed for estimating both the fundamental and harmonic...
Thomson coil actuators (also known as repulsion coil actuators) are well suited for vacuum circuit breakers when fast operation is desired such as for hybrid AC and DC circuit breaker applications. This paper presents investigations on how the actuator drive circuit configurations as well as their discharging pulse patterns affect the magnetic force and therefore the acceleration, as well as the mechanical...
Capacitively-coupled wireless power transmission utilizes electric field applied between physically separated metal plates. Especially in full wireless power system which has no battery inside the target object, how to provide the regulated output voltage through the resonant LC link are challenging task. In this paper, analysis and control design of such system are investigated. Transfer function...
This paper proposes a novel automatic mode transition control strategy for multiple inverters to operate in grid-connected and islanded modes without communication. When grid is available, all the inverters operate in grid-tied current control mode and transfer available power to the grid. On grid failure, they automatically shift to conventional droop control mode and shift back to grid-tied current...
Synchronization is a crucial aspect in grid-tied systems, including single-phase photovoltaic inverters, and it can affect the overall performance of the system. Among prior-art synchronization schemes, the Multi Harmonic Decoupling Cell Phase-Locked Loop (MHDC-PLL) presents a fast response under grid disturbances and high accuracy under harmonic distortions. However, major drawbacks of the MHDC-PLL...
In this paper, a new DSC-PLL (Delayed Signal Cancellation Phase Locked Loop) with FLL (Frequency Locked Loop) based on RDFT(recursive discrete fourier transform) method is proposed for coping with frequency variation. This method shows significant performance improvement for detection of fundamental positive sequence component voltage when the grid voltage is polluted by grid harmonics and frequency...
The Inrush Transient Current (ITC) in the output of the photovoltaic grid-connected inverters is usually generated when grid voltage sag occurs, which can trigger the protection of the grid-connected inverters, and even destroy the semiconductor switches. Then, the grid-connected inverters will thus fail to ride through the voltage sag and even further cause more serious grid faults. This paper analyzes...
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