EMC Partner AG

Whitepapers from EMC Partner AG

Charging station and EV connected through Coupling/Decoupling Network: A Signal Analysis

This EMC Partner white paper analyzes the signal distortions that arise when a standard IEC 61000-4-5 Coupling/Decoupling Network (CDN) is interposed between a DC charging station and an electric vehicle (EUT) during surge and burst immunity testing. DC charging stations typically use PWM-modulated trapezoidal current pulses, and when the CDN's decoupling inductors interact with the capacitances in the charging circuit, both voltage and current at the EUT terminals become distorted — most critically, negative voltage and current spikes appear that can cause errors or interrupt the charging process. The paper uses circuit simulation to quantify these effects and to evaluate the two remedies introduced in Amendment 1 of IEC 61000-4-5 Edition 3: using a CDN rated for a higher current (reducing decoupling inductance), which only partially mitigates the negative distortions, and inserting a diode-resistor network between the power source and the CDN. Simulation results across three cases show that a parallel resistance of 100 ohms across the diode completely eliminates negative voltage and current distortions at the EUT terminals. The paper concludes that distortion severity scales with the PWM voltage slew rate, the decoupling inductance value, and the EUT input capacitance, and recommends using the lowest parallel resistance value that fully eliminates negative disturbances to avoid potential overvoltage.

Automotive EMC

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Damping Factor (Q) computation for MIL-STD-461 CS116 signal with new TEMA3000 formulae function

This EMC Partner application note explains how to use the formulae function introduced in TEMA3000 software version 4.9.0 to automatically compute the damping factor (Q) required for MIL-STD-461 CS116 conducted susceptibility testing. The CS116 requirement specifies a damping sinusoidal transient waveform with a Q value of 15 ± 5, calculated from the ratio of the first current peak to a later peak near 50% decay. The note describes how TEMA3000's "Do advanced measurements" DSO trigger action allows operators to define custom formulae using oscilloscope measurement variables, mapping the first current peak and the fourth peak to the standard Q equation and expressing it directly in TEMA3000 syntax. Step-by-step configuration is covered for three components: the MIL-MG3 generator with MIL3-10K10M plugin and CN-BT6 coupler, the oscilloscope channel and gating settings needed to isolate the correct peaks, and the TEMA3000 Single Test definition including trigger setup and limit bounds of 10 to 20. The resulting Q factor is computed automatically for every impulse and included directly in the test report alongside frequency, amplitude, and oscilloscope screenshots, eliminating manual post-processing and reducing the risk of calculation errors.

MIL-STD-461Oscilloscopes

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Experiences with level 5 requirements for indirect lightning tests to RTCA DO-160

This whitepaper from EMC Partner examines the practical challenges of conducting indirect lightning tests to RTCA DO-160 Section 22 at the highest severity level — Level 5. It begins by distinguishing between DO-160's two lightning-related sections: Section 22, which covers lightning-induced transient susceptibility tested at the equipment (LRU) level, and Section 23, which addresses direct lightning strikes on whole aircraft. The document explains how equipment location within an aircraft determines which of four protection zones applies and, consequently, which waveform sets and test levels are required — ranging from Level 1 for well-protected cabin environments to Level 4 or 5 for landing gear and propulsion controls in composite-heavy airframes. A key technical focus is the distinction between PIN injection and cable bundle tests, clarifying that generator impedance is defined solely by PIN injection parameters and that "Test" and "Limit" values for cable bundle tests are frequently misunderstood. The paper works through the generator output voltage demands of Waveform 3 at 1MHz and 10MHz, demonstrating how cable inductance can cause voltages to reach tens of kilovolts under certain conditions, making simultaneous achievement of both voltage and current test levels difficult. For longer, higher-energy waveforms (WF1, WF4, WF5), the paper notes that Level 5 single-stroke generators must deliver twice the output of Level 4 equipment, and that separate generator designs are typically needed for single-stroke versus multiple-stroke testing. The document concludes by recommending a modular, scalable approach to test equipment investment: rather than purchasing a dedicated Level 5 system for occasional use, laboratories are better served by expanding an existing Level 3 or 4 platform, which reduces costs, avoids retraining, and preserves flexibility for future requirements.

DO-160

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Indirect Lightning Testing and the Influence of Couplers

This EMC Partner whitepaper examines the role of inductive couplers in DO-160/ED-14 indirect lightning cable bundle testing and explains how coupler design choices directly affect waveform integrity and system impedance. The paper contrasts capacitive and inductive coupling methods, noting that while capacitive coupling is simpler and more predictable, it is impractical for aircraft power systems and high-energy waveforms. Inductive couplers must be built from the correct core material — ferrite for low-energy, short-duration waveforms and laminated silicon steel for high-energy, long-duration pulses — because saturation of the core material causes significant waveform distortion. The coupler turns ratio is shown to have a direct and counterintuitive effect on virtual system impedance: increasing the turns ratio to reach higher test currents simultaneously reduces virtual impedance, which can make it impossible to achieve both the voltage limit and current limit simultaneously on hybrid cable bundles. Measured waveform data illustrates that inserting a short-circuit cable loop inside a coupler during WF2 application causes voltage distortion and suppresses current well below the required limit level. The paper concludes that hybrid generator/coupler systems can overcome these calibration and impedance issues but are large, heavy, and costly, making practical DO-160 compliance difficult.

CouplersDO-160

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Indirect Lightning Testing using Waveform 3

This EMC Partner whitepaper addresses a fundamental technical limitation in performing indirect lightning testing using Waveform 3 (WF3) at 10 MHz as defined in RTCA/DO-160 and EUROCAE ED-14. WF3 is a damped sinusoidal waveform derived from lightning transients near aircraft, and its frequency is inversely proportional to cable length. While WF3 at 1 MHz presents no serious challenges for PIN injection or cable bundle testing — the required generator impedance of 25 ohms and short-circuit current of 128A are achievable — applying WF3 at 10 MHz introduces significant practical problems. Load impedance increases by a factor of ten between 1 MHz and 10 MHz, and a 1-metre coaxial cable more than doubles the effective test equipment impedance at 10 MHz, distorting the waveform and severely limiting achievable current. When a coupler is added for cable bundle testing, the required series inductance to maintain the correct oscillation frequency results in very high impedances, meaning that reaching the DO-160 limit current of 640A at level 5 would require generator charging voltages of tens of kilovolts — impractical and potentially damaging to the device under test. The paper concludes that the DO-160 provision allowing the generator to not produce the associated limit current in such cases should be rigorously applied, and presents the EMC Partner AVI-LV3 combined generator as a practical compliant solution.

DO-160Couplers

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