EMI testing is an important part of testing in the automotive sector

The automobile industry attaches great importance to safety. In addition to the power electrification of automobiles in recent years, the role of digitalization is increasing. The traditional vehicle EMC electric testing technology has long been unable to meet the requirements, and EMI testing in EMC has always been an important part of vehicle testing. However, the test takes a long time. The problem of not capturing detailed signals is a problem that the whole industry has to face. I used to be a person in the process of EMC online live broadcast. I heard some users and solution providers share some information based on the new EMI technology in EMC. The following points will be briefly sorted out according to what I heard.

1、 Vehicle EMI introduction

First, let's know what it is called. EMI。

EMI (interference signal) refers to the interference signal of equipment to external environment during normal operation. EMI mainly includes CE (conducted interference) and RE (radiated interference) CE refers to the influence of power line, power line or control line transmission, and RE refers to the influence of product shell radiation.

Theoretically, many electronic products are installed in a very tight space with great differences, which may spread EMI to the outside world. The vehicle route is complex, and the motor control system is complex. Multimedia entertainment. Bluetooth communication GPS electronic products may also send interference signals to the external environment, that is, vehicle EMI.

2、 Necessity of vehicle EMI test

Speaking of vehicle EMI industry, people can cite a lot of typical cases, such as:

During the performance test of the ABS of the oil-electric hybrid bus, the wheel speed curve of the test equipment fluctuates abnormally when the vehicle is started but not running; However, the wheel speed curve of the instrument is completely normal in terms of the characteristics of ABS for traditional diesel passenger cars

A car is equipped with sensitive ABS. When it rains, the interference signal caused by the wiper operation mistakenly triggers the ABS, resulting in a rear-end collision accident

The integrated console of a mass production vehicle displays the instrument panel mosaic caused by the camera signal

FM radio noise fault caused by engine ignition of a certain vehicle

So, how to solve the vehicle EMI hazard? Technical shielding can be used to eliminate, ground, reduce effective wiring and other forms of EMI, and vehicle EMI detection.

Today, vehicles are developing rapidly towards electrification, intelligence and networking. EMC testing of new energy vehicles faces more tests: large current, large current and high power lead to more serious interference signals, and the coupling mode between components is more complex; High-frequency switchgear. Perceived load is a serious electromagnetic transmission and radiation interference generated by automotive equipment and systems in the normal operation process, and electromagnetic compatibility is facing greater challenges; The control circuit is complex and the anti-interference requirement is high.

How to operate the vehicle in this more complex electromagnetic environment? In order to ensure safety, EMI detection and evaluation are more critical.

3、 Relevant reference standards and standards of vehicle EMC

EMI test is a part of EMC test, and EMC test has veto power. If the corresponding regulatory test requirements are not met, auto products cannot be sold. Next, sort out some common Chinese and international vehicle EMC specifications.

ISO11451-4: Road vehicles - Interference signals generated by narrowband radiated electromagnetic energy - Vehicle test methods - Part 4: Introduction of large current (BCI) method

ISO11451-4: Road vehicles - Electrical disturbance from narrowband radiated electromagnetic energy - Vehicle test methods - Part 2: External radiation sources

CISPR12: Vehicles - Limits and methods of measurement of radio scratch characteristics of motor boats and internal combustion engine driving devices

CISPR25: For maintenance vehicles - Limits and methods of measurement of radio scratch characteristics on motor boats and equipment

GB/T36282-2018: Electromagnetic Compatibility Requirements and Test Methods for Electric Vehicle Drive Motor Systems

GB4824: Measurement methods and limits of electromagnetic disturbance characteristics of industrial, scientific and medical (ISM) frequency shooting equipment

The problem of vehicle EMC has been paid more and more attention. Many standards and regulations limiting vehicle electromagnetic compatibility have been formulated around the world and relevant global institutions. In addition to China and international vehicle EMC standard systems, the United States, Europe, and international electrician and other EMC standard systems, the natural vehicle factory also has its own EMC Volkswagen standard systems, such as VQTL81000 and SAIC SMTC3800006.

4、 Vehicle EMI detection solution

Vehicle EMI test is divided into EMI full compatibility test and EMI pre-compatibility test.

（1） Vehicle EMI full compatibility test

The vehicle EMI testing industry mentioned above has two main problems: high cost of compliance testing, long time testing and traditional step scanning. It is unable to capture detailed signals. Keysight N9048BPXE exponentially accelerates EMI compliance detection and can seamlessly capture all signals.

Keysight N9048BPXE is a qualified EMI detection receiver equipped with frequency preselector and LNA design. Real-time scanning (RTS) is conducive to reducing the overall test time of vehicle EMI, and is easy to achieve seamless signal capture and analysis. The N9048BPXE has the following features

1Hz – 44GHz frequency range

Conform to the actual CISPR16-1-1:2019. MIL-STD-461G. ANSIC63.2 and FCC standards

Good sensitivity and dynamic range

Time domain scanning (TDS) overall test time can be significantly reduced

Instant scanning captures all signals

Intuitive multi-touch operation interface and PXE software

X can update the series to meet current and future test requirements

For example, in the process of vehicle EMI detection, the traditional step scan detection must take 9 hours for one face and 36 hours for four faces. The N9048BPXE time domain scan significantly reduces the test time. It only takes 50 seconds to detect one face and 200 seconds to detect four faces. Accelerated time domain scanning is more efficient. It only takes 6 seconds to detect one face and 24 seconds to detect four faces.

Traditional step scanning can not capture detailed signals, but real-time scanning RTS. It can conduct seamless scanning without any signal, capture the maximum bandwidth to 350MHz, quickly locate the interference source or cause, and is a powerful troubleshooting tool. At the same time, it can record up to 12000 data for future review and analysis.

（2） Vehicle EMI pre-compatibility test

In addition to the EMI full compatibility test, the EMI pre-compatibility test can also be carried out to check the problems that may occur in the compliance test in advance and prevent the compliance test, but it takes a long time to improve the detection efficiency and save the enterprise costs.

KeysightX - or MXR oscilloscope RTSA function fusion N9311X near-field probe. N6141EM0EEMI measurement system software system software EMI pre-compatibility test.

1. RTSA (real-time analysis)

RTSA of MXR oscilloscope, detection bandwidth up to 320MHz; As long as the signal duration reaches 5 microseconds, 100% can be detected; The rate is 400000 FFT/S; Applicable to Tupu, power, etc. It indicates that the heavier the color on the spectrum, the greater the probability of electromagnetic interference. Its characteristics are as follows

Choose aliasing FFT and fast hardware

Fast, 100% capture probability (POI)

It is applicable to fast signal spectrum detection, such as burst signal, pulse radar signal, unknown electromagnetic interference, etc.

2. Multi-touch monitoring software N6141EMOE

Keysight multi-touch software N6141EMOE is an electromagnetic compatibility testing software, which is satisfied with CISPR and GB embedded bandwidth standards. The detector and frequency band are preset to automatically test the limit line of laws and regulations, and has the capacity selected by customers; Antenna application. LISN. Cable. Amplitude calibration of preamplifier. Formation of test report; Through the extensive spectrum analysis level, the pre-compliant radiation and transmission transmission measurement are implemented to diagnose the non-compliant transmission. It has the following characteristics:

Simultaneous display of multiple frequency spans and three detectors

Reduce measurement time according to embedded signal catalog and supervision frequency band

Accelerate data acquisition based on optional time-domain scanning function

Multi-touch operation interface and SCPI remote page programming

3. N9311X near-field probe

Use the Keysight N9311X near-field probe to scan the circuit board in a targeted way, gradually locate the noise source and transmission path, and rectify the EMI problem.

EMI full compatibility tester N9048BPXEEMI fast receiver. Total wide time domain scan greatly reduces test time; According to the general X-series signal analysis platform, it has completed higher property efficiency and integrated the N9311X near-field probe. The multi-point touch software N6141EMOE searches the fault source, finds the interference signal problem, clears it in the morning, and speeds up the sales of qualified products. Therefore, such equipment and instruments help enterprises greatly improve EMI testing efficiency and save costs.