E-Mobility for Components and EMC – Simulation and Measurement
This article highlights IMG Electronic & Power Systems and University of Ruse Angel Kanchev simulation models of E Mobility for Components and EMC.
For the current simulation are taken into account only conducted emissions. Radiated emissions can be implemented in the future in a three dimensional model. The created simulation models are designed in order to be connected with other PSpice models in order to make a complete model of the test E-car.
The depletion of fossil fuels and the rising of the fuel prices in the recent years have led to an increased interest of the car manufacturers in the construction of hybrid and electrical cars. On the other hand the requirements that are set for EMC of the elements of such new machines are very strict and hard to accomplish. Having in mind the high price of the car elements for these new types of cars it was found more acceptable and cost effective to simulate the behaviour of the machine in software applications and to test the EMC effects on the simulation model until good results are achieved.
Data for the simulation / Technical parameters
The schematic of the test electrical car is presented on figure 1. The elements of the car with highest EMC emissions are used for this study.
Figure 1: Schematic of the test E-car
For the simulation is used data from the technical parameters of the corresponding real devices in the test E-car, namely:
- Motor drive
- Frequency-voltage converter,
- DC/DC voltage converter,
- Battery with BMS.
EMC Simulations results
The frequency of the PWM control signal is 50 KHz. The duty cycle depends on the form of the required sinusoid. The selected frequency of the sinusoid is 660 Hz, which corresponds to the maximum load of the electrical motor and it is the heaviest operational mode.
Figure 2: Wave forms of phase A signal and PWM control signal
The red line (Vn005) in the graphics represents the form of the sinusoid measured between phases A and B. In the current simulation model are used no additional filtering capacitors. That‘s why the sinusoid on the graphic has some fluctuations from the ideal sinusoid form. The green line (Vn008) is the control signal of the upper transistor from the bridge and the blue line (Vn004) shows the control signal for the lower transistor.
On figure 3 is presented the Fast Fourier Transformation (FFT) of the output sinusoid.
Figure 3: FFT of the output sinusoid
On the figure can be seen that there is one main harmonic at 50 kHz, followed by higher harmonics. There is one peak at around 20 MHz, which has the highest negative effect on the signal and has to be eliminated.
EMC Measurement results
At the following measurement figures 4 and 5 the very high disturb EMC voltage is at the grafics.
Figure 4: EMC voltage measurement at the battery line
Figure 5: EMC voltage measurement at the frequency/ voltage transducer
The result of the practical measurement is, that the EMC test at the standard EN 61000-6-4 is NOT PASSED.
We have many very high disturb effects. The simulation result have the same characteristic of the measurement grafics, but the simulation result is not full the same characteristic like the practical measurement.
The reason is, that the EMC model have only the galvanic coupling effect and not all EMC coupling effects.
But the simulation and the measurement result is, that the EMI is very high and not pass the test.
The simulation models of the e-car components were made based on default parameters. The technical characteristics of the real experimental device can be different from the simulation ones and thus the simulation results might differ from the experimental results. Based on the result from the simulation can be concluded that an external input filter have to be used in order to improve the EMC characteristics of the device. The simulation results invoke the conclusion that the operating frequency of the filter has to be DC up to 60 Hz and the current should be rated according to the batteries used.
For output filter we recommend that a sine wave filter for motor drives with motor frequency 0- 1000 Hz and motor power up to 35 kW should be used. Such filters are easily available on the market.
About the Authors
F. Gräbner or Frank Gräbner received his Theoretical Electrical Engineering, Materials of Electrical Engineering degree at Technical University Ilmenau. He worked as an assistant professor at University of Ruse Angel Kanchev Bulgaria.
L. Iliev or Iliya Iliev received his industrial heat engineering at University of Ruse Angel Kanchev, and water treatment and fuel technologies at Moscow Power Engineering Institute (Technical University). He worked as a full-time professor at University of Ruse Angel Kanchev Bulgaria.
S. Yanev or Stoyan Yanev received his Doctor of Philosophy in Electrical and Electronics Engineering at Ruse Angel Kanchev. He worked as an ISO specialist at Steiner Electric Ltd.
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This article originally appeared in the Bodo’s Power Systems magazine.