Juha-Pekka Ström

A Review of Microstrip T-resonator Method in Determination of Dielectric Properties of Printed Circuit Board Materials

When designing devices at microwave frequencies, the characteristics of printed circuit board materials should be well known in order to attain exact functionality. The characterization can be carried out for example with T-resonator test method. In this paper, microstrip T-resonator test method is analyzed. The analysis is based on literature search and experimental research, and the practicable calculation methods are introduced. The introduced modifications provide more precise calculation improving the accuracy of the method. The modifications also enable the determination of dielectric properties of high loss printed circuit board materials at broad frequency and temperature ranges

A new method to measure dielectric constant and dissipation factor of printed circuit board laminate material in function of temperature and frequency

In this article, a new method to measure the values of dielectric constant and dissipation factor of printed circuit board laminate material in function of temperature and frequency is presented. The method is based on the use of microstrip ring resonator structures and a climate chamber. The presented method is experimentally tested at frequency range from 1 GHz to 10 GHz and at the temperature range from -30/spl deg/C to 105/spl deg/C. With the presented method, frequency properties of different laminate materials and coatings can be measured at wide frequency and temperature range.

Modular double-cascade converter

A new multilevel converter topology with cascaded H-bridges and a multi-winding medium frequency isolation transformer is introduced. The proposed converter topology has a modular structure, which is achieved using cascaded H-bridges. The isolation for the H-bridges is provided by medium frequency isolation transformers which are small compared with line frequency transformers with the same power rating. The building blocks of the proposed converter topology can be connected in series or in parallel. Series connection adds voltage steps to output voltage, and parallel connection increases the power rating of the converter.

Active

Active du/dt is a new output-filtering method to mitigate motor overvoltages. The inverter pulse pattern edges are broken down into narrower pulses, which control the filter LC circuit. This results in an output voltage that does not have to exhibit the overshoot typically seen in common LC circuits in output-filtering applications. Furthermore, the shape of the output-voltage edge has properties well suited for output-filtering applications. An appropriate filter rise time is selected according to the motor-cable length to eliminate the motor overvoltage. The basis of the active du/dt method is discussed in brief. Considerations on the application of the active du/dt filtering in electric drives are presented together with simulations and experimental data to verify the potential of the method.

du/dt

A microstrip ring resonator structure is used to determine the dielectric constant and dissipation factor of FR-4 type printed circuit board material. The article presents essential information on the microstrip ring resonator measurement method, characteristics of the microstrip line losses, and dielectric constant and dissipation factor calculation techniques. Based on the presented information, the dielectric properties of high loss printed circuit board materials can be determined for a wide frequency band.

—New Output-Filtering Approach for Inverter-Fed Electric Drives

A new approach to determine dielectric properties of printed circuit board materials is presented. The new method is based on the use of a strip line ring resonator structure and utilization of the thru-reflect-line calibration method. An experimental research was carried out with one FR-4 type material in a frequency range from 1.0 GHz to 10.0 GHz and in a temperature range from -35/spl deg/C to 105/spl deg/C. The method was noted to be applicable for determination of dielectric properties as a function of frequency and temperature.

Determination of dielectric constant and dissipation factor of a printed circuit board material using a microstrip ring resonator structure

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.

A strip line ring resonator method for determination of dielectric properties of printed circuit board material in function of frequency

In this article a new method to evaluate, effects of moisture absorption on dielectric constant and dissipation factor in function of temperature and frequency are presented. The development of method is based on the experimental measurements and the use of ring resonator structures implemented to FR4-type material. The experimental measurement procedure was carried out at frequency range from 1 GHz to 10 GHz. The used temperature points were 23/spl deg/C and 85/spl deg/C. The results gained by the presented method were observed to be reproducible and consistent with the amount of the absorbed moisture. The method can be applied to different printed circuit board materials.

Acoustic Emission in Power Semiconductor Modules—First Observations

This paper addresses common-mode (CM) and radio frequency (RF) electromagnetic interferences (EMI) in a converter-fed low-voltage direct current (LVDC) distribution research network. The LVDC distribution is a novel approach to public electricity distribution, and a research site is set up to enable comprehensive studies concerning the LVDC distribution. Because the customers in the LVDC system are supplied with customer-end inverters (CEI), CM and RF EMI generated by the CEIs have to be analyzed. To this end, common-mode currents in the DC network and the customer-end networks are studied by on-site measurements. The objective is to determine whether there are disturbances that exceed the requirements of the standards or whether the CM current could cause safety issues in the converter-fed user-end network. In the DC network, the effect of the CM current on the feasibility of power line communication (PLC) in a DC network is analyzed. Finally, RF disturbances are measured and discussed.

A method to evaluate effects of moisture absorption on dielectric constant and dissipation factor of printed circuit board materials

Frequency converters are used to increase the controllability and efficiency of electric motor drives. Induction motors may experience an insulation failure caused by an overvoltage at the motor terminals. The overvoltage is caused by an impedance mismatch between the motor terminals and the motor cable. Fast pulse rise times compared with the propagation delay in the motor cable will make the terminal voltage exceed the DC link voltage level. Passive filtering techniques for two-level inverters have been developed to cancel out the overvoltage. In this paper, a control method for active du/dt filtering to reduce motor terminal overvoltage is introduced. A filter topology and the basis for setting the filter component values are presented. The size of the passive filter used in this filtering method is smaller than in traditional passive du/dt filters. Functional filtering can be achieved with a smaller filter by controlling the filter output voltage rise time with an accurately timed inverter output voltage. The control of the system is implemented on a field programmable gate array (FPGA) to provide precise gate drive signals with high time resolution.