ISO7637 automotive EMC immunity test introduce

Since the development of the modern automobile industry, a large number of on-board electronic devices have been introduced. Among them, the most common ones are lighting systems, anti-theft systems, automatic air conditioning systems in traditional cars, as well as car navigation, audio-visual entertainment systems and more complex connected car Tboxes in modern cars, ADAS driver assistance systems and so on. Various electronic loads work at the same time and cooperate with each other, requiring a stable power supply system. Therefore, high-performance in-vehicle power supply design is the key to the safe, stable and reliable operation of modern vehicles.

Below we will gradually expand the various interference waveforms of ISO7637 automotive EMC testing, including a brief test method, so that you can understand the test significance of ISO7637 in a short period of time. ISO7637 specifies 5 pulse tests in the EMC requirements for automotive electronic equipment on power supplies:
Test 1: When simulating the product in parallel with the inductive load, if the power supply is suddenly disconnected, the voltage between the two ends of the inductive load will be applied to the product power supply end in reverse, which is a medium speed and medium energy pulse interference in the ISO7637 automotive EMC test, and it is necessary to rely on the anti-reflective circuit at the product power supply to withstand both interference and destruction of the tested device.

Waveform plot1

Test 2: One is to simulate the stray inductance on the power supply harness, due to a load disconnection in parallel, causing the current change in the stray inductor of the wiring harness at the power supply, and then produce a positive voltage superimposed on the power supply, which requires the product power supply port to have a surge clamping device, which is a positive pulse interference with fast speed and small energy in the ISO7637 automotive EMC test. The other is to simulate a DC motor acting as a generator, igniting the transient phenomenon when the switch is turned off. When the power supply is disconnected, the DC motor is equivalent to a generator, generating a positive voltage applied to the power supply, which is a bit like energy recovery in the ISO7637 automotive EMC test.

Waveform plot2

Test 3: Simulate transient phenomena caused by switching processes. The characteristics of these transient phenomena are affected by the distributed capacitance and distributed inductance of the wiring harness, which are high-speed, low-energy small pulses in the ISO7637 automotive EMC test, which can often cause malfunction of devices controlled by microprocessing or digital logic.

Waveform plot3

Test 4: Simulates the reduction of the power supply voltage generated by the starting motor circuit of the internal combustion engine when it is energized, which in turn causes the voltage fluctuation at the power supply of the product.

Waveform plot4

Test 5: The load-throwing test is a very brutal and destructive test. The alternator on a running car suddenly cuts off the load, called a single throw; At the same time as cutting off the load, the battery is cut off, which is called double throw, which is a relatively large pulse of energy in the ISO7637 automotive EMC test. Load-dump testing is to simulate the phenomenon of load-dumping transients, while disconnecting the battery, the alternator is generating charging current, and there are still transients generated when other loads are on the generator circuit, the current in the coil of the generator is larger when it is not disconnected, and the sudden current becomes smaller when disconnected, generating a reactionary potential. In practice, cars due to cable corrosion, poor contact, disconnection from the battery while the engine is running are all causes of load dumping.

Waveform plot5

ISO7637 Part 2《Electrical Transient Conduction Testing of Power Supply Lines》specifies bench tests for conducted electrical transient electromagnetic compatibility testing of equipment installed in passenger cars and light commercial vehicles with 12V electrical systems or commercial vehicles with 24V electrical systems, including transient injection and measurement, and also specifies the severity classification of transient immunity failure modes. This standard applies to road vehicles with a variety of independent powertrains.

Therefore, Shanghai LISUN GROUP launched EMS-ISO7637 automotive multifunctional immunity test system fully meets newest ISO7637-2 <Road Vehicles – Conductive Coupling Electrical Interference – Part 2 Electrical Transient Conductivity Tests for Power Lines> , ISO16750-2, ISO7637-1, GB-T21437.2 requirements. This standard was issued by international organization for standardization. LISUN EMS-ISO7637 system includes all the waveforms required by ISO7637-2 and it meets most of automotive manufacturer’s requirement for automotive electronic immunity test.

Technical Characteristics:
• This system includes all the waveforms required by ISO7637-2: 2011 standard (ISO16750-2 is optional).
• Operation screen: Adopted with big colorful LCD touch screen and applied with main module expand technology architecture design.
• Designed for 12V/24V automotive electronic immunity test.
• Built-in various host interfaces and can work with LISUN software on a PC.
• The software includes all relevant standards, and customers can also add or update the standards.

EMS-ISO7637_ Multifunctional Immunity Test System For Automotive Electronics

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

Our main products are Goniophotometer, Integrating Sphere, Spectroradiometer, Surge Generator, ESD Simulator Guns, EMI Receiver, EMC Test Equipment, Electrical Safety Tester, Environmental Chamber, Temperature Chamber, Climate Chamber, Thermal Chamber, Salt Spray Test, Dust Test Chamber, Waterproof Test, RoHS Test (EDXRF), Glow Wire Test and Needle Flame Test.

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