Lusheng Ge

A New High Efficiency Current Source Driver With Bipolar Gate Voltage

A novel bipolar current source driver (CSD) for power MOSFETs is proposed in this paper. The proposed bipolar CSD alleviates the gate current diversion problem of the existing CSDs by clamping the gate voltage to a flexible negative value (such as -3.5 V) during turn-off transition. Therefore, the proposed driver is able to turn off the MOSFET much faster with a higher effective gate current. The idea presented in this paper can also be extended to other CSDs to further improve the efficiency with high output currents. The experimental results verify the benefits of the proposed CSD. For buck converters with 12 V input at 1 MHz switching frequency, the proposed driver improves the efficiency from 80.5% using the existing CSD to 82.5% (an improvement of 2%) at 1.2 V/30 A, and at 1.3 V/30 A output, from 82.5% using the existing CSD to 83.9% (an improvement of 1.4%).

Research on current control strategy for grid-connected inverter based on passivity based control

In the micro-grid, the grid-connected inverter and its filter are important to convert and transmit the energy. In this paper, a T filter is used to reduce the harmonics of the grid-current. However, it will be lack of enough stability. In order to overcome this obstacle, a new passivity based controller, namely IDA-PBC is proposed in this paper. And the paper analyses the stability of the controller in detail. The correctness and validity of the proposed control algorithm are proved to achieve stability with good stability and dynamic ability by simulation and experimental results.

Research of WSN Node localization algorithm based on Weighted DV-HOP

The node localization algorithm is one of the key technologies in WSN. In the paper, a Weighted DV-HOP algorithm is proposed based on traditional DV-HOP algorithm. And a improving simulation model is employed to confirm the changes of localization accuracy. Comparing DV-HOP algorithm, simulation shows that the WDV-HOP algorithm can increase localization accuracy by above 2% with the same conditions which includes the percentage of anchor node, the scope of radio range and the network connectivity. Conversely, under the same accuracy request, the number of percentage of anchor node can be reduced obviously to lower the network investment cost.

The study on DC/DC converter based on fixed-frequency sliding mode control method

The sliding variable structural control method has been used in DC/DC converter widely and show the excellent dynamic performance and the strong robustness, but the conventional sliding mode control, whose control rule is sign function, has some shortcomings, for which switching frequency is uncertain and control result is serious influenced by the sliding surface parameters and the circuit parasitic. In this paper, a novel fixed-frequency sliding mode control is proposed for control rule changed with duty cycle. The proposed method can make system worked at a fixed frequency, having better dynamic characteristics than the traditional sliding control. It is easy to realize with digital circuit after analysis. The correctness and validity of proposed control algorithm are proved by simulation results.

Dual channel current-source gate drivers for high-frequency dc-dc converters

In this paper, resonant gate driver techniques for power MOSFETs are reviewed at first. To solve the exiting problems of the drive circuits previously proposed, new dual channel current-source gate drivers are presented here. The new drive circuits can achieve quick turn-on and turn-off transition time to reduce the switching loss of power MOSFETs significantly by constant gate drive currents due to the parasitic inductance, especially the common source inductance. A 12 V synchronous buck VR prototype at 1 MHz switching frequency was built to demonstrate the advantages of the new drive circuits. A significant efficiency improvement over the conventional gate voltage driver is achieved.

A Communication Protocol With Data Compression for Isolated Digital Power Supplies

High-cost isolators and their speed limits are the shortcomings of digital control in isolated power supplies. Different feedback schemes result in different numbers and speed requirements of the isolators, which impact the cost and the decision making. This paper compares existing solutions, and proposes a communication solution featuring data compression and time-division multiplexing, which provides the highest output accuracy and many advanced features of digital control, whereas the cost can potentially be in the range of conventional analog solutions.

Research on static VAR generator with direct current control strategy

The operating principle of three-phase static VAR generator (SVG) with voltage source inverter (VSI) structure is analyzed in detail. Adopting a novel direct current control strategy under abc coordinate system, this paper realizes the rapid detection of system reactive current by applying instantaneous reactive power theory. On the basis of double closed-loop controlling method with voltage and current, the hybrid control approach based on the feed-forword control of grid voltage and DC voltage is proposed, which can eliminate the disturbance of grid voltage fluctuation and flicker and suppress the fluctuation of capacitor voltage at DC side effectively. The excellent static and dynamic performances of the system could be obtained. Finally, system simulation and experimental studies are performed respectively, and the results further verify the feasibility and effectiveness of the proposed control strategy.

A single-phase grid connected inverter with a power pulsation decoupling circuit on the AC output

In the single-phase grid connected inverter, a power pulsation with twice the grid frequency is contained in the input power. In the conventional inverter, electrolytic capacitor with large capacitance has been used in order to decouple the pulsation. But, the electrolytic capacitor has a drastically shortened lifespan when used in high-temperature environment. This paper presents a single-phase grid connected inverter with a power decoupling circuit on the AC output. A most distinctive feature of the proposed system is that the ripple energy appeared on the input DC capacitor is transferred into the energy in an inductance on the additional decoupling circuit. Hence, the large electrolytic capacitor can be replaced by the small film capacitor. This paper presents the proposed topology and its control requirement. Finally, the new topology is verified through MATLAB simulation.

Double integral sliding mode control of paralleled dc/dc converters

The use of dc-dc converters connected in parallel is a suitable way to solve the technological problems that arise in large-capability power supply systems. This paper presents a new approach to parallel converters using double integral sliding mode control. This approach could alleviating the steady-state regulation error and enhancing dynamic current-sharing property by increasing the order of the proportional integral sliding mode (ISM) controllers using an additional integral term. Theoretical analysis and simulation results are provided for verification.

Research on delay-dependent stability of parallel DC-DC converter system based on a Wireless communication

The current-sharing technology based on Wireless communication allows the current of DC-DC parallel system to be divided equally very well. However, the information transmitted by the network inevitably exist a transmission delay, which makes the traditional system into a time-delay systems. This paper presents a method to compute the Critical Delay of a DC-DC Parallel delay system. The method uses frequency-domain techniques and the DC-DC Parallel System linearized average model to obtain the critical delay. Then a Simulation Model with two parallel modules was built. And the main circuit of the modules is BUCK converter. Finally using the MATLAB simulation tools, we demonstrate the correctness of the method.