Mikko Kuisma

A New Passive Hybrid Air-Core Foil Filter for Modern Power Drives

This paper introduces an alternative implementation of the traditional LC filter, called hybrid LC filter (HLCF). The construction described in this paper contains two foil windings that integrate inductance and capacitance into one unit. The main aspects of the HLCF design are considered. The experimental data show that the device proposed here can be used, instead of traditional LC filters, as an alternative solution for the mitigation of the adverse effects of the pulse-width modulation (PWM).

Using spectrograms in EMI-analysis - an overview

Spread-spectrum techniques have raised their importance as a common EMI-reduction technique in power supplies. Ability to track and measure such a signal is vital. Analysis and synthesis of an effective spread-spectrum sequence is also important. Pulse-type and apparently random interference are other types of signals which are hard to detect and measure, but still very common in practice. In this paper a spectrogram, a time-dependent spectrum analysis is proposed as a practical tool for EMC-design and measurements. Basic theory and selected examples of spectrogram in EMC-engineering are presented.

Acoustic Emission in Power Semiconductor Modules—First Observations

Traditionally, condition monitoring of power semiconductor modules has been based on electrical measurements. Acoustic emission has been utilized for condition monitoring in many other applications, but is an unknown phenomenon in power semiconductor modules. In this paper, the authors present an experimental setup used to show that acoustic emission does occur because of the switching of power semiconductor components. An analysis based on propagation delays is used to determine the source of the acoustic emission.

Sliding mode control for buck-boost converter using control desk dSPACE/sup /spl trade//

Switch mode power supplies have been controlled using different control algorithms like PID control, current mode programmed control etc. Many control tools were used to implement these control techniques e.g. analog operational amplifier, microprocessor. This paper focuses on using a new control tool called dSPACE/sup /spl trade// for controlling the switch mode power supply. Programming the control circuit via MATLAB/Simulink/sup /spl trade// can be made. The prototype of the basic three converters buck, boost, and buck-boost can be controlled by the simulation model via real time hardware. Buck-boost converter was chosen as our prototype converter. The sliding mode control (SMC) was chosen as a control algorithm in MATLAB/Simulink/sup /spl trade// for controlling the buck-boost prototype model. The reason behind choosing SMC is that it is an efficient control and simple to implement in MATLAB/Simulink/sup /spl trade//. The paper shows that the control algorithm represented by SMC in MATLAB/Simulink/sup /spl trade// and using the dSPACE/sup /spl trade// as control toolbox is able to control the prototype model.

Analyzing voltage ripple in variable-frequency DC/DC boost converter

Numerous variable-frequency (VF) EMI-reduction schemes have been proposed over the last decades. The aim of these VF or spread-spectrum techniques is to reduce both the measurable and effective undesirable electromagnetic noise of a switch mode power supply. Conducted RF-interference measurements have been reported in literature. However, low frequency output voltage ripple has been considered as a major problem in VF DC/DC converters and the majority of these papers do not consider this aspect of VF operation. Analysis of the output voltage ripple with four different VF techniques in six different configurations is made in this paper, and prototype measurements with a boost converter are presented.

Sounds from semiconductors - Acoustic emission experiment with a power module

A recent paper showed that the switching operation of a power semiconductor module causes an acoustic emission to take place. In this study, that experiment is repeated using a different kind of acoustic emission sensor. The same conclusion is reached in this stydy as in the previous paper: an acoustic emission takes place as a result of the switching of a power module.

Analyzing Current Ripple in Variable-Frequency Boost Converter

Electromagnetic interference (EMI) remains one of the main problems in switch mode power supplies (SMPS). Various EMI reduction schemes for switching converters using switching modulation have been proposed over the last decades. These variable-frequency (VF) modulation techniques include quasi-random system clock generation, random or quasi-random modulation of the system clock frequency, frequency modulation (FM) of the system clock, sigma-delta modulation, chaotic peak current control and hysteresis control. Voltage and current ripple have been considered a major problem with VF-modulated power supplies. The analysis of input current in boost converter using VF modulation is presented in this paper.

Acoustic emission caused by the failure of a power transistor

The authors show for the first time that acoustic events are related to the failure of transistors. An experimental setup is presented, that was used to make a sample of 26 insulated gate bipolar transistors (IGBT) to fail. The acoustic events in the transistors were monitored. It was discovered that two distinct types of acoustic events are related to the failure. This study complements recent work where it was shown that the switching operation of power transistors causes acoustic emissions to take place.

Time-variant electrical equivalent circuit of a dry bacteriorhodopsin sensor

Modeling the photoelectric response of dry bacteriorhodopsin (bR) sensors has commonly been carried out by following the theory of linear time-invariant systems. However, it has been reported that the time constants of the photovoltage responses of such sensors vary depending on whether the sensor is measured when the incident light is switched on or off. In this paper, we propose an electrical equivalent circuit for dry bR sensors. Unlike the models presented in the literature, the proposed circuit also considers the illumination on the bR sensor. The model is experimentally verified by photocurrent measurements. Further, a new result concerning the photocurrent dependence on the illumination of dry bR sensors is introduced.

Using Switching Function in Preliminary EMI-analysis of a Switching Power Supply

Electromagnetic interference (EMI) is usually difficult to predict and the interference problems may dramatically lengthen the time-to-market of a new power supply product. The possibility of predicting the EMI-spectrum from the switching function of a switching power supply by means of simulation is analyzed in this paper. Simulated spectra are compared to the measurements made with a spread-spectrum DC-DC converter