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Application note: MD line for EV service

Application note: MD line for EV service
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Application note: MD line for EV service - 1

Application Note MD line for EV service Electric vehicles have a new spectre of needs when it comes to servicing. Electrical faults, while essentially rare, can cause serious hazards to both the user and the service personnel. Electrical effects like electrolysis on material contact or battery leakage have to be considered during design. Regulation for electric cars is currently still weak. The UN regulation UNECE R100 prescribes safety features for the battery, most of which have to be tested by the manufacturer. After the battery is installed, internal systems in the car monitor its status. Few car models allow any kind of electrical testing and consider the on-board monitoring enough. Some tests should still be done in case of a suspected failure. MD 9070's main strengths are insulation measurement with up to 1000 VDC test voltage, and continuity test with 200 mA test current. It measures TRMS voltage up to 1000 V AC or DC, frequency with or without a VFD filter, resistance, diode test, and tests for continuity with audible signal. It allows for a number of diagnostic and safety tests in cars or elsewhere. • Testing battery pack’s nominal voltage with the voltmeter, • Faults on PCBs with audible continuity, resistance measurement and voltmeter, • Controlling signals on electric motors with VFD filtered frequency, • Testing insulation between any live and any accessible parts while live parts are off, • Testing continuity of wires, • lectric motor start-up test E with MAX/MIN/AVG recorder and a current clamp. MD 9272 is an AC clamp with lowest range down to 0.1 μA. It makes it a great tool for leakage analysis. In an EV, leakage is a powerful diagnostic tool at every point in its operation, from charging to driving. Its power functions and harmonic analysis offer additional layers of service. It can perform some functional tests on the inverters and motors, and particularly assure the inverters cause no

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Application note: MD line for EV service - 2

MD 9273 is the upgrade on the MD 9272. It contains all the features in MD 9272 and a number of extras, the main of which is Bluetooth connection to MI 3155 and work in tandem. It can trace inrush current and the application on MI 3155 will draw a graph. On the other hand, MI 3155 can generate a signal into the wiring system that can be traces with MD 9273. Bluetooth also enables easy upgrades of the firmware and the features list will eventually grow. Optional accessories provided by Metrel that are necessary for some of the mentioned measurements are the A 1734 reference resistance R0, and...

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Application note: MD line for EV service - 3

Testing insulation on the battery system Battery system is in the UN ECE R100 referred to as Rechargeable energy storage system or RESS. MD 9070 makes its name as basic installation tester also with testing for continuity. Continuity with 200 mA measuring current is mainly used to test the car’s PE wire from any higher-voltage device to the chassis. The car is not grounded as in actually connected to the ground, and the chassis is used as voltage reference. That makes it an IT system, and insulation is the more important safety parameter. 200 mA is a standard test current for 230 V...

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Application note: MD line for EV service - 4

Measuring motor controller with VFD frequency filter MD 9070 is equipped with a low pass filter for debugging VFD type of drives. VFD is a mainly industrial motor controller. It creates a pulse-width modulated signal to precisely control motor’s speed and torque. Motors equipped with it are amongst most energy efficient for variable-torque applications. It is not very common in the cars, but can be found in some models. The pulse-modulated signal is very rich in high-frequency components, making it impossible for the regular multimeter to measure its base frequency and voltage correctly....

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Application note: MD line for EV service - 5

Modern types are electronic and generally shouldn’t cause too much trouble, but faults or bad design can cause overheating and damage other parts of the installation or even the batteries. The system has to be tested for leakage, power parameters and distortion. Leakage is measured by turning the rotary switch to Ampere symbol and clamping the relevant wires. Usually, that is the PE for direct measurement, or both live and neutral wires for the differential measurement. Functional testing and harmonics Functional test is device-specific and often cannot be done using a measuring device....

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Application note: MD line for EV service 5Pages

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Application note: MD line for EV service
5Pages