Reducing switching losses through MOSFET-IGBT combination

This paper introduces a configuration aimed at switching losses reduction trough a power leg constructed by combining a MOSFET and an IGBT. The combined use of these different switches leads to the turn-on losses reduction trough the use of the faster freewheeling diode of the IGBT, and the turn-off losses reduction trough use of the MOSFET’s lower losses because of the lack of tailing current, typical for IGBT’s. The introduced leg structure can be used to build single phase – full bridge invertors or three phase inverters. The proposed leg is realized, experimented and validated

Thermal design of transformers and inductors in power electronics

An overview of convection and radiation heat transfer in magnetic components is proposed. Firstly an introduction in ‘rule of the thumb’ is given. Secondly an improved modeling is proposed. It comprises natural convection heat transfer including also the effects of the orientation of the component and the influence of the ambient temperature. The proposed modeling is verified by comparison with experimental data obtained for an experimental box shape. The carried out accurate measurements for four different kinds of surfaces of the experimental model allow a fine-tuning of the improved expression for convection heat transfer coefficient. Thirdly an approach for forced convection is given. The derived results can be used in thermal design of magnetic components as well for other electronic equipment

Applications of combined MOSFET-IGBT power leg with reduced switching losses

This paper discusses power legs built upon the combination of a MOSFET and an IGBT. The suggested combined use of those different switches is intended to be applied in PWM controlled single and three phase inverters. The main advantage of the presented topology is the reduced switching losses in the overall inverter topology compared to the classical pure IGBT and MOSFET topologies. The paper presents and compares experimental results for the proposed power leg and the conventional pure IGBTs and pure MOSFETs legs. Realized applications of the proposed power leg are shown

Comparison of multiple stage braking circuits for wind driven generators

This paper presents multiple stage braking circuits for wind turbines with a permanent magnet synchronous generator. The system combines both passive converter circuit coupled to a resistive braking circuit. The second one is an over voltage protection when an emergency situation of no load is detected. The power converter control and braking are simulated and the output power/frequency graphics are derived. Three braking circuits are analyzed and compared. Design recommendations are formulated regarding the application of different topologies depending of the wind speed and the input assignment

Programmable logic device based brushless DC motor control

In this article a three-phase BLDC motor controller for use in an Ultra-Light Electrical Vehicle is presented. The control is performed using a Programmable Logic Device (CPLD), which doesn’t require any additional processor. In this way a robust and low-complexity control is obtained. For extending the speed range of the BLDC, a phase advance circuit is implemented as well. The power consumption of the controller is very low which is an interesting feature in battery applications

A simplified controller and detailed dynamics of constant off-time peak current control

A fast and reliable current control is often the base of power electronic converters. The traditional constant frequency peak control is unstable above 50 % duty ratio. In contrast, the constant off-time peak current control (COTCC) is unconditionally stable and fast, so it is worth analyzing it. Another feature of the COTCC is that one can combine a current control together with a current protection. The time dynamics show a zero-transient response, even when the inductor changes in a wide range. It can also be modeled as a special transfer function for all frequencies. The article shows also that it can be implemented in a simple analog circuit using a wide temperature range IC, such as the LM2903, which is compatible with PV conversion and automotive temperature range. Experiments are done using a 3 kW step-up converter. A drawback is still that the principle does not easily fit in usual digital controllers up to now

Design considerations and loss analysis of DC chokes

The paper presents design considerations and a loss analysis of dc chokes in kW range, realized by different magnetic materials. Five designs under the same input parameters are realized with three different materials: ferrite (3F3), powder (sendust MS) and amorphous material (Microlite 245). An optimal design procedure is considered aimed at minimizing losses and volume of the component. A set of operating and construction parameters is analyzed. The obtained design results are verified by carried out simulations. Three of the compared DC chokes are realized, experimented and measured under the real operating conditions. The comparison of the three different materials is summarized and design recommendations are formulated regarding their use is such applications