Hamidreza Ghorbani

A Novel Active Gate Driver for Improving SiC MOSFET Switching Trajectory

The trend in power electronic applications is to reach higher power density and higher efficiency. Currently, the wide band-gap devices such as silicon carbide MOSFET (SiC MOSFET) are of great interest because they can work at higher switching frequency with low losses. The increase of the switching speed in power devices leads to high power density systems. However, this can generate problems such as overshoots, oscillations, additional losses, and electromagnetic interference (EMI). In this paper, a novel active gate driver (AGD) for improving the SiC MOSFET switching trajectory with high performance is presented. The AGD is an open-loop control system and its principle is based on gate energy decrease with a gate resistance increment during the Miller plateau effect on gate–source voltage. The proposed AGD has been designed and validated through experimental tests for high-frequency operation. Moreover, an EMI discussion and a performance analysis were realized for the AGD. The results show that the AGD can reduce the overshoots, oscillations, and losses without compromising the EMI. In addition, the AGD can control the turn-on and turn-off transitions separately, and it is suitable for working with asymmetrical supplies required by SiC MOSFETs.

Posicast control — A novel approach to mitigate multi-machine power system oscillations in presence of wind farm

In this paper, application of Posicast control method to generator excitation system is presented. The method is one of the simplest possible control design methods that can be applied to damp the oscillations caused by changing the excitation reference signal. Stability and robustness of the designed controller are shown using extensive time domain simulations. All the detailed simulations are carried out in MATLAB/Simulink environment.

A novel active gate driver for silicon carbide MOSFET

A novel active gate driver (AGD) for silicon carbide (SiC) MOSFET is studied in this paper. The gate driver (GD) increases the gate resistance value during the voltage plateau area of the gate-source voltage, in both turn-on and turn-off transitions. The proposed AGD is validated in both simulation and experimental environments and in hard-switching conditions. The simulation is evaluated in MATLAB/Simulink with 100 kHz of switching frequency and 600 V of dc-bus, whereas, the experimental part was realised at 100 kHz and 100 V of dc-bus. The results show that the gate driver can reduce the over-voltage and ringing, with low switching losses.

Application of Posicast control method to generator excitation system

Application of Posicast control method to generator excitation system is presented in this paper. Presented control method is one of the simplest control design methods which can be installed in generators excitation to damp the oscillations caused by changing the excitation reference signal. Stability of the designed controller is shown using extensive time domain simulations. Performance of Posicast controller in IEEE power system standard models with presence of PV power plant is evaluated in MATLAB/Simulink environment.

Performance analysis of conventional PSS and fuzzy controller for damping power system oscillations

Electro-mechanical oscillations are produced, in the machines of an interconnected power network, followed by a disturbance or due to high power transfer through weak tie lines. These oscillations should be damped as quickly as possible to ensure the reliable and stable operation of the network. To damp these oscillations different controllers, based on local or wide area signals, have been the subject of many papers. This paper presents the analysis of the performance of Conventional Power System Stabilizer (CPSS) and Fuzzy Logic Controller. Two area 14 bus symmetrical system is considered to demonstrate the performance of these controllers using Simulink/MATLAB. Simulation results depict fuzzy logic based controller having dual inputs of rotor speed deviation and generators accelerating power is the better cost effective solution for damping the inter area oscillations specifically, in comparison with conventional power system stabilizer.

A novel EMI reduction design technique in IGBT gate driver for turn-on switching mode

This paper proposes a novel insulated gate bipolar transistor (IGBT) gate driver. The new gate driver (GD) has positive effect on the injected gate current to enhance the IGBT switching mechanism. The approach is based on the Posicast control method. Simple structure is the most important advantage of this feedforward controller. The main objective is to improve turn-on switching transients without harmful effect on the IGBT efficiency. The electro-magnetic interface (EMI) reduction has been discussed as another important benefit of this control method.

Impacts of wind energy in-feed on power system small signal stability

Integration of large amount of wind energy in an interconnected power system creates concerns about secure, reliable and economical operation of the entire power system. So it becomes very necessary to investigate the impacts of wind power infeed on the dynamic behavior of the power system. This paper presents the impacts of large amount of wind power in feed on the rotor oscillatory stability. Wind turbine generator types currently employed in wind farms, optimal location of the wind farms in the interconnected power system, reliable optimal dispatch of the wind power and the degree of tie line congestion have been thoroughly investigated. Kundurs two area network model has been utilized to study the mentioned impacts on the overall system using MATLAB/Simulink. Some of the key results show that the damping characteristics of the wind farms critically depend on the location of interconnection in the network and the optimal wind energy dispatch. Increasing the penetration of the wind energy generally improves the damping of the inter area oscillations. Moreover, reducing stress on the weak tie lines also improves the inter area mode of oscillation. So with the investigation of these impacts this study is helpful for the planning of new wind power projects.

Performance of a new gate drive controller for improving IGBT switching trajectory

This paper presents a new active gate control (AGC) approach for improving the switching behavior of insulated gate bipolar transistors (IGBTs). The proposed controller is applied on the gate driver (GD) of IGBT, which is based on Posicast control method. The reduction of stress in transient conditions without harmful effect on the efficiency is the main objective of this research that is accomplished by a simple feed-forward controller. The effectiveness of the proposed gate drive controller is verified by both MATLAB/Simulink and PSIM softwares. Moreover, the new GD is implemented in the experimental setup, and the results are reflected in this paper.

Embedding a feedforward controller into the IGBT gate driver for turn-on transient improvement

Abstract This paper proposes an active gate drive method based on a feedforward control for turn-on condition in IGBTs. The transient improvement with minimum undesirable effect on the efficiency is the main objective of this research. The new gate driver (GD) improves the trade-off between switching loss and device stress at the turn-on condition, without getting feedback from the output. The operation principle and implementation of the controller in the GD are presented. The effect of the proposed GD on the transient behaviour, efficiency, junction temperature and electromagnetic interference (EMI) during turn-on switching is evaluated by both simulation and experimental tests. The new GD is evaluated under hard switching condition and various frequencies. Advantages and disadvantages of the method have been discussed.

A simple gate drive for SiC MOSFET with switching transient improvement

This paper presents a new active gate drive for SiC MOSFETs switching. The proposed driver is based on feedforward control method. The switch is benefited from a simple and effective analog gate driver (GD). The main achievement of this GD is the transient enhancement with minimum undesirable effect on the switching efficiency. Also, the electromagnetic interference (EMI) as the main threat to the operation of SiC MOSFET is eliminated by this method. The proposed GD has been validated through the simulation and experimental tests. All the evaluation have been carried out in a hard switching condition with high-frequency switching.