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Use Cases
Use Cases

Measuring Shield Current of High-Voltage Cables in Electric Vehicles

The high-voltage cables of the high-voltage vehicle electrical systems in modern electric vehicles are exposed to strong current and voltage ripples, which induce currents in the braided shields. If these shield currents exceed the capacity of the braided shield, cable fires and damage to connected accessories are the result. To ensure the safety of the system, extensive measurements of the shield currents are necessary.

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Background

High-voltage cables have an braided shield for safety and mitigation of electromagnetic interference. Large current and voltage ripples, which can occur due to high-frequency switching power electronics, determine the curve and the level of these shield currents. The length and diameter of the cables can further increase the effects. If the braided shield is not sufficiently dimensioned, cable fires can be caused due to the high temperature of the cables and PG glands on housings, and damage the entire system.

Measurement task

Measurement of currents in the braided shield to ensure that the capacity of the shield is not exceeded.

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Challenge

High voltage electrical system of an electric vehicle
Shield current measurement on an electric truck. The length of the cables causes different shield currents in the different areas of the high-voltage electrical system. At the measuring points marked in red, the shield current is measured in the individual HV cables with CSM HV breakout modules.

Shield currents must be measured in all cables of the high-voltage vehicle electrical system, which means that a large number of measurement points is required. The measurement data must be recorded synchronously at a high sampling rate of 1 MS/s. This is the only way to acquire current peaks and analyse the effects of different load conditions on all areas of the system. Another challenge is the actual application of the shield current measurement, as the braided shield must be separated from the inner conductor and a low-resistance connection must be established between the measurement technology and the braided shield. In addition, high-voltage safety must be ensured, as voltages continue to be applied to the inner conductor during the measurement. At the same time, temperatures on the cables and screwed connections should be measured in order to be able to make statements about the stress on the power installation.

Cross section through a HV cable
Construction of high-voltage cables.
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The CSM-Solution

  • For the measurement of shield currents, HV Breakout Modules (BM) 1.2 /S are inserted directly into the HV cables. This version of the CSM HV Breakout Modules was developed especially for the measurement of shield currents: The cable shield is applied to the measurement shunt, through which the shield currents are measured at a high sampling rate.
  • A temperature measurement module HV TH4 evo can simultaneously acquire temperatures on the cables and fittings.
  • The XCP Gateway pro captures the measurement data synchronously via EtherCAT® and CAN bus and converts them to XCP-on-Ethernet. With the XCP Gateway, the measurement setup can also be easily extended with further measurement modules, such as HV BM 1.2 for parallel current, voltage and power measurement.
  • With the Vector software vMeasure exp or CANape the acquired data is analyzed and recorded in real time. The partnered solution from CSM Hard- and Vector Informatik Software allows all necessary performance parameters to be calculated online with the eMobilityAnalyzer.
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Benefits

Thanks to the HV BM 1.2 /S, shield currents can be acquired synchronously and at a high data rate at many points in the vehicle electrical system. Due to the robust design, testing is also possible in road tests and the high-voltage vehicle electrical system can be designed safely. The high-voltage safe CSM measurement modules ensure the safety of the user and the measured object during the measurement.

Due to the coordinated software and hardware, up to 40 measurement channels, each at 1 MHz, can be acquired simultaneously and synchronized with the Vector-CSM measurement system, in order to also carry out multi-channel, distributed vehicle applications. The Precision Time Protocol (PTP) ensures data synchronization in the measurement system.

Users can trigger on specific events or calculate other variables relevant to the test. Examples are current peaks or signal derivations to correlate certain events with other measured variables over time. The measurement system can be expanded with a Vector interface if the vehicle is to be calibrated with the analysis computer via the serial POD (Plug on Device) interface. Advantageous is that control unit measurement variables are recorded simultaneously with the measured values of the CSM modules.

Download

Here you find the complete application report for download as PDF.

Verwendete Produkte

Verwendete Hardware

Hochvolt Breakout-Module zu Leistungsmessung

HV Breakout Modules

Direct measurement of current, voltage and power

The HV Breakout Modules (BM) have been specifically designed for safe measurement applications on cables carrying high voltage. Current and voltage are evaluated and the power calculated online in the module.

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XCP-Gateway

XCP-Gateway

The protocol converter for EtherCAT® and CAN to XCP-on-Ethernet

XCP-Gateway is the interface between the data acquisition software (e. g. vMeasure, CANape®, INCA®, Vision® ...) and the EtherCAT® measurement modules from CSM. It includes an EtherCAT® master and an XCP-on-Ethernet slave.

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Product HV TH

HV TH Measurement Modules

Safe temperature measurements with thermocouples on high-voltage components: the high-voltage-safe temperature measurement modules are specifically designed for the reliable acquisition of temperatures in electric and hybrid vehicles.

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Verwendete Software

Software CSMconfig

Logo CSMconfig

Swift configuration of measurement chains: CSMconfig is the reliable configuration software for all CAN and EtherCAT® based measurement modules from CSM. The clearly arranged and easy-to-use user interface allows an easy setting of all measurement parameters. This helps speeding up the measurement setup considerably.

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vMeasure exp

vMeasure exp

vMeasure exp, developed by Vector Informatik, is an easy-to-use software tool for the acquisition and analysis of measurement data that can be used in combination with all CAN- and EtherCAT®-based CSM measurement modules. CSMconfig was integrated directly to ensure swift configuration.

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