With economic and social development, the traditional energy situation is becoming increasingly strained. Against the backdrop of rising energy demands, actively developing new energy sources has become a consensus across society. New energy vehicles are a typical example of this development. One of the biggest differences between new energy vehicles and traditional vehicles is their powertrain. The powertrain is the core of a car and is key to energy conservation.
The core components of a new energy vehicle's power system are the motor and controller. The performance of the motor and controller directly affects the overall performance of the new energy vehicle. With traditional energy sources becoming increasingly scarce and new energy sources emerging rapidly, strengthening electromagnetic compatibility testing of motors and controllers used in new energy vehicles helps ensure the quality and improve the performance of these vehicles.
1. Reasons for compatibility testing of new energy vehicle powertrain systems
Currently, the main power system used in my country's new energy vehicles is the drive motor system, which has significant advantages over traditional internal combustion engine systems. However, the power system for new energy vehicles in my country is still in the research stage and has not yet been widely adopted. During normal operation, the power system of new energy vehicles emits strong radiation and electromagnetic interference due to the extremely short fluctuations in current and the rapid movement of high-power semiconductor switches. For example, the switching on and off of an insulated-gate bipolar transistor, although only lasting tens of nanoseconds, can generate strong electromagnetic interference within those few nanoseconds. Electromagnetic interference from the power system can seriously affect the performance of new energy vehicles and severely impact their electrical systems. Therefore, to reduce electromagnetic interference, we must strengthen electromagnetic compatibility testing.
Currently, my country's new energy vehicle compatibility testing technology is not yet mature and lags significantly behind other countries. Most compatibility tests for new energy vehicle powertrain systems in my country rely on traditional internal combustion engine drive systems and low-voltage electrical systems standards. my country currently lacks a complete and scientific standard for new energy powertrain system compatibility testing. This is an area that warrants our reflection.
2. Contents of Electromagnetic Compatibility Testing for Power Systems
Electromagnetic compatibility (EMC) testing for new energy vehicle powertrain systems mainly refers to two aspects: interference testing and immunity testing. To achieve scientific testing, it is essential to accurately grasp the meaning of these two aspects and to strictly adhere to relevant national standards.
2.1 Harassment Testing Harassment testing primarily refers to testing the ability to protect personnel within a certain distance. The current standard for harassment testing is GB14023-2006. While this standard has expanded its content compared to the previous one, adapting to certain requirements for new energy vehicles, it is ultimately a standard for internal combustion engines.
This standard makes scientific testing impossible. It primarily calculates the operating status of the tested object in kilometers per hour, whereas new energy vehicles are measured in revolutions per minute. The calculation standards are significantly different. Furthermore, the different setup methods are also a major reason for the failure of compatibility testing. Measuring the powertrain separately is significantly different from testing the powertrain installed in a new energy vehicle. The setup methods are significantly different, rendering compatibility testing meaningless.
2.2 Immunity Testing Immunity testing mainly refers to testing the electromagnetic radiation immunity of electronic components in motor vehicles. Currently, the reference standard for immunity testing in my country is GB/T17619-1998. This standard clearly specifies the immunity limits and test methods. Since the electromagnetic compatibility testing environment for drive motor systems is roughly the same as that for traditional vehicle compatibility testing, using GB/T17619-1998 as a reference is feasible.
3. Feasibility Study for Electromagnetic Compatibility Testing of New Energy Power Systems
Having understood the main content of power system compatibility testing, this article will discuss feasible solutions for electromagnetic compatibility testing of motors and controllers used in new energy power systems. For drive motor system compatibility testing, we mainly need to consider two factors: first, clearly defining the test object; and second, scientifically arranging the drive electromechanical system and effectively monitoring its operation.
Define the test target.
Our primary focus in electromagnetic compatibility (EMC) testing of motors used in the electrical systems of new energy vehicles is the drive motor as a whole. Traditional testing methods separate the major components of the electrical system and the inverter for independent testing. This layered testing approach yields poor results and is costly. Therefore, we adopt a holistic measurement approach to conduct compatibility testing of the drive motor system.
The scientific arrangement of the drive motor system is crucial. The arrangement of the drive electromechanical system significantly impacts test results. Careful selection of the arrangement during testing is key to ensuring accurate measurements. Currently, relevant Chinese standards do not specifically specify arrangement methods, or while some provisions exist, they are not suitable for drive motor system testing. Therefore, when arranging the drive motor system, we primarily refer to the arrangement methods used in simulation experiments.
During system compatibility testing, it is generally necessary to load the drive motor system. Loading the drive electromechanical system can effectively improve the launch performance. I have conducted experiments specifically on this topic, and together with professionals, I built a special testing trolley. In this trolley, the drive motor system is primarily loaded using a chassis dynamometer.
After using this loading method, the author observed through experimental data that the emission level was significantly improved, increasing by 50 dB compared to the average level. System loading is key to improving the performance of the drive electromechanical system. During the measurement process, conditions must be utilized to load the system. While recognizing the benefits of system loading, it's also important to be aware of the many limiting factors currently existing in the loading process of new energy vehicle systems in my country. Two of the most typical factors are: first, achieving system loading requires a specially designed semi-anechoic chamber, which significantly increases testing costs; second, current system loading technology in my country is not yet mature and cannot adapt to complex situations. When conducting compatibility testing on drive motor systems, these two factors must be fully considered. Optimization of compatibility testing under given conditions is crucial.
4 Compatibility Testing Standards
After understanding the feasibility of measuring the electrical systems of new energy vehicles, it is also crucial to accurately grasp the various testing standards. Mastering these compatibility testing standards is essential for scientific testing. Our selection of reference standards for compatibility testing is primarily based on the following aspects:
Firstly, we examine the issue from the perspective of radiated emissions. Currently, the main reference standards for radiation protection are GB18655-2002 and GB/T18655-2002. These two standards are primarily used for measuring the receiving devices inside new energy vehicles. These standards have a very wide range of applications. If the drive motor system is compatible with these two standards, then the various devices inside the vehicle can achieve better performance. For example, through a professional examination of the drive motor system of a new type of new energy sedan from the perspective of radiated emissions, the author found that while the vehicle meets the GB18655-2005 standard, its radiation protection performance still needs improvement.
Secondly, radiated immunity. For measuring radiated immunity, we primarily use the GB/T17619-1998 standard. The main reason for using this standard is that it clearly specifies the immunity limits and measurement methods, and also clearly defines the measurement frequency range. While this standard is not specifically designed for measuring the electromagnetic compatibility of motors used in new energy power systems, we adopt it because the electromagnetic radiation environment is not significantly different from that described in the standard.
Thirdly, conducted immunity. Testing of conducted immunity is primarily conducted according to standards such as ISO 7637-3-2007 and ISO 7637-2-2004D. These standards clearly specify the test methods for transient conducted immunity of the vehicle's 24V power supply line. According to these standards, there are eight pulse forms for conducted immunity: 1, 2a, 3a, 3b, 2b, 4, 5a, and 5b. The first four forms can be used for compatibility testing.
With the increasingly strained traditional energy situation in my country, accelerating the development of new energy sources has become a consensus across all sectors of society. Currently, the development and application of new energy vehicles in my country has effectively alleviated the energy shortage. However, because the power systems of new energy vehicles emit strong electromagnetic radiation during normal operation, electromagnetic compatibility testing of the motors and controllers becomes extremely important.
This article provides a detailed analysis of the reasons for compatibility testing, its main content, testing methods, and reference standards. The author believes that the key to successful compatibility testing lies in developing innovative and feasible solutions.
