Design of Three phase to DC zener regulated supply for DC battery charging

Description The Zener diode block modeled in this example presents a practical implementation that uses parameters commonly provided on datasheets. These parameters are (1) Zener Voltage Vz (2) Dynamic Impedance Zzt (3) Knee Impedance Zzk (4) Max Continuous Current Izm (5) Forward Voltage Drop Vf (6) On Resistance Ron This block can effectively model three regions of operation of the zener diode I-V characteristics - forward-biased, reverse-biased before breakdown and reverse-biased after breakdown. Beyond the maximum reverse continuous current Izm, the zener is assumed to burn up and is treated as an open circuit. The implementation of the zener diode can be seen by looking under the mask of the block. Zener diodes are commonly employed in applications as voltage regulators. The circuit shows an AC source fed to a step-down transformer. The output of the transformer is then rectified using a diode bridge and smoothened using a capacitive filter. The zener diode then acts to regulate the output voltage to the zener voltage 10V. The input current into the zener is limited by the resistor Rlimit to permissible values. The programmable voltage source is setup to increase its output voltage at 0.1s. As the source output increases, so does the voltage applied at the input of the zener. However, the zener can regulate the output only as long as its input current is below the maximum specified value. This current increases as we increase the source voltage and the zener ultimately fails at about 0.112s. With the zener acting as an open-circuit at fault, voltage regulation is lost and the output of the capacitive filter gets applied to the load. Result:

Three Phase flying capacitor inverter

Project ideas: Design and analysis of three phase cycloconverter for variable load

The objective of this study is to observe the correlations between variable operating conditions and power quality parameters for a three-phase to single-phase cycloconverter. The cycloconverter is examined in its most straightforward form without additional output filters or elaborate control methods. Variable operating conditions include input frequency, output frequency, and resistive load size. The power quality parameters of interest are power factor, input current total harmonic distortion (THD), output voltage THD, and efficiency. The scope of the project includes analytical calculations, Matlab/Simulink simulations, and /or hardware implementation. The results show that output frequency has minimal effect on power quality. Total harmonic distortion undesirably peaks at a combination of low input frequency and high output frequency. Extrapolations can be made for the cycloconverter operating at different frequencies and loads based on the trends observed within the test matrix. This can be a good design and innovative exercise to perform.

SCR Rectifier Full wave

Parallel operation of chopper Simulink model

This model simulates the parallel operation of a boost converter. The results of simulations can be analysed in the next figure

Model of current controlled voltage source