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In this paper, we demonstrate 20 A operation and high switching frequency 980 KHz of single chip DC/DC converter. The fabricated chip consists of the digitally control block, the low on-resistance MOSFET switches and the drivers. The chip adopted low impedance metal bump technology. The on resistance of Nch MOSFET is 4.3m (@drain current=10 A, gate voltage=5 V) comparable to the discrete device. The...
This paper focuses on the non-inverting buck-boost converter supplying an adjustable DC voltage to a WCDMA RF power amplifier (RFPA) in order to improve the system efficiency under different transmitted RF power levels. It is shown that precise output voltage positioning and low output voltage ripple over a wide output voltage range, including buck, boost and buck/boost transition modes, can be accomplished...
This paper introduces an LED drive circuit implemented by series input connected converter cells with a common duty cycle control approach operating from a dc voltage bus. With this structure, low voltage high frequency ICs and low profile components can be applied in high voltage applications. Flexibility is provided for the cells to work under different voltage supply conditions by simply changing...
To overcome the drawbacks of the conventional gate drive, in this paper a closed-loop gate control method is proposed. In this novel method, the switching speed, specifically di/dt, is measured from the voltage across the parasitic inductance of the IGBT module and a closed-loop control is employed to adaptively adjust the gate drive voltage to control the switching speed according to a preset control...
To improve efficiency over a wide load range, it is important to dynamically adjust the operational phase number in multiphase voltage regulators. This paper analyzes in detail the power loss profile of a synchronous multi-phase buck converter and defines the optimal phase number under different load conditions. Experimental results are provided to verify the theoretical results.
In this paper, an active gate control method for high power IGBTs in wind power generation system is investigated. With this method, the turn off voltage of the high power IGBTs using Trench-/Field-Stop technology can be clamped at proper level. The implementation of the control strategies is also introduced, which has been used in the practical wind power generation system. It is based on the control...
High brightness (HB) LED provides higher efficacy and reliability over incandescent light bulb. Different from incandescent light bulb, HB LED needs to be driven by accurate constant current for consistent brightness and color-temperature light emission. With a novel method pulse-level-modulation (PLM) control applied on conventional switched-mode power stage, a more robust, power-efficient and accurate...
The peak-current control that is modeled in this paper is a novel variable-frequency control that maintains regulation in a flyback converter by enabling and disabling cycles instead of modulating the pulse-width, which allows for elimination of feedback compensation and can provide for peak power 3 times higher than the rated full load power without increasing the power supply component sizes. A...
Design consideration of a three-phase inverter with 1200 V Si-IGBT and SiC-JBS hybrid pairs has been implemented to further reduce the power loss and increase the power density. A low-on-voltage SiC-JBS has been developed to reduce the conduction loss. In order to minimize the switching loss of Si-IGBT, a high-speed gate driving technique is introduced. A 4 kVA class three-phase hybrid pair inverter...
To integrate low on-resistance high voltage power devices with control circuits in single chip is difficult, since lateral power devices usually have higher on-resistance and higher process costs compared to vertical power devices. Using trench lateral power devices, single chip 5 A DC-DC converter have been designed and fabricated. In order to simplify fabrication processes and to reduce chip area,...
This paper proposes a new recovery circuit for the capacitive load. Connecting the one side of windings to the load together, the resonant current is shared in both windings, hence the conduction loss is reduced. Simple circuit structure with transformer achieves the reduced the number of devices. Furthermore, the current-balance transformer enables ZVS operation of the switching device. To confirm...
Conventional wisdom that the SiC JFET is only a normally on device has recently been superseded by the first practical normally off SiC JFET. This new true enhancement mode, three-terminal, pure-SiC design provides designers with a normally off solution that retains all the benefits of the normally on SiC JFET. With only a simple change in series gate impedance, the EM SiC JFET can be used with common...
Multilevel inverters are traditionally seen as a step forward in DC/AC conversion, providing more output voltage levels, better quality of the generated waveform and lower switching losses than the two-level and can process higher voltages with a given forced commutated switch technology. There are also drawbacks associated with this technology: more switching devices and associated gate driver circuitry,...
In a commutation cell, the implementation of IGBT and MOS requires an insulated signal. Traditionally, the insulated signal is carried out by a DC supply with a high insulation transformer for energy transmission and an optical fiber or pulse transformer for the switch control information. A new approach seems promising: the switch control information by a wireless transmission. Analog or digital...
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