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Electromagnetic Compatibility Assurance for High-Quality Vehicle Power Systems
As a key node in the vehicle power network, vehicle-mounted DC-DC converters perform core power conversion functions in automotive electronic systems. For example, they convert the high-voltage system of new energy vehicles (such as 400V to 1500V battery pack voltage) to low voltage (12V to 48V), providing stable and reliable power supply for vehicle electronic devices (such as infotainment systems, sensors, lighting equipment, etc.).
Electromagnetic Compatibility (EMC) testing is a systematic evaluation of electronic devices' ability to operate normally in an electromagnetic environment and avoid causing interference to other devices. Its core lies in ensuring that devices can both suppress their own electromagnetic emissions and resist external electromagnetic interference in complex electromagnetic environments, forming the fundamental link for maintaining the compatibility of automotive electronic systems.
Focuses on limiting the electromagnetic disturbance of equipment to the outside world, including radiated disturbance and conducted disturbance, based primarily on CISPR 25 and GB/T 18655
Evaluates the functional safety of equipment under external electromagnetic interference, requiring selection of test methods such as Bulk Current Injection (BCI), Free field, Conducted transient, and Electrostatic Discharge (ESD) based on product characteristics
The regulatory compliance and market access requirements for vehicle-mounted DC-DC products exhibit mandatory constraint characteristics globally, with their core manifestation being the mandatory application of mainstream regulations in China and the European Union and the rigid threshold for market access.
GB/T 18655-2025 "Vehicles, boats and internal combustion engines - Radio disturbance characteristics - Limits and methods of measurement for the protection of on-board receivers" (Effective from February 28, 2025)
CISPR 25:2021 (Fifth Edition) serves as the core standard, covering the frequency range from 150 kHz to 5925 MHz
The binding nature of regulations on DC-DC products is reflected in the dual aspects of supply chain access and official certification:
Analyzing from the perspective of the "interference source - coupling path - sensitive device" model, the electromagnetic compatibility of vehicle-mounted DC-DC products is directly related to the functional safety and reliability of the entire vehicle.
High-frequency noise intrudes into the low-voltage power supply network through power lines, potentially causing BMS (Battery Management System) voltage sampling deviations or unstable power supply to ADAS controllers
Utilizing the antenna effect of wiring harnesses, electromagnetic energy is radiated to surrounding sensitive devices, such as autonomous driving sensor wiring harnesses, causing signal distortion or false triggering
With the rapid evolution of intelligent connected and new energy vehicle technologies, the electromagnetic environment faced by vehicle-mounted DC-DC products is becoming increasingly complex. Electromagnetic Compatibility (EMC) performance has become a core element in technological development and market competition.
The application of C-V2X communication technology prompted the CISPR 25:2021 standard to add test requirements for the 5850-5925MHz frequency band
The GB/T 18655-2025 standard covers the 1553-1569MHz frequency band test to ensure navigation signals are free from interference
The ISO 7637-4:2021 standard has added transient conducted emission test requirements for 60-1500V high-voltage power systems
The international core standard system for vehicle electromagnetic compatibility is based on the framework of CISPR 25:2021, establishing a dual-dimensional normative system covering electromagnetic emission and immunity.
The domestic vehicle electromagnetic compatibility (EMC) testing standard system is centered on GB/T 18655 and GB 34660, and has been continuously updated in recent years with the development of intelligent connected vehicle technology.
| Standard Name | Effective Date | Main Updates |
|---|---|---|
| GB/T 18655-2025 | February 28, 2025 | Test frequency range extended to 6GHz, added Beidou navigation frequency band (1553-1569MHz) |
| GB 34660-2025 | 2025 | Radiated immunity test frequency band extended to 20MHz-6GHz, added functional failure judgment criteria |
Current domestic and international vehicle EMC standards show a development trend of "convergence as the main, differences as secondary." In terms of convergence, domestic and international standard systems are accelerating integration, with core technical content gradually unifying.
The core goal of Conducted Emission (CE) testing is to control the electromagnetic noise conducted by vehicle-mounted DC-DC products through power lines and signal lines, ensuring that their radio frequency emission levels comply with relevant standard limits to avoid polluting the vehicle power grid.
Radiated Emission (RE) testing is a key means to evaluate the intensity of electromagnetic energy propagated through space by vehicle-mounted DC-DC converters. Its core goal is to quantify the spatial electromagnetic interference generated during vehicle operation, ensuring that it does not cause interference to vehicle receivers and other electronic systems.
Antenna selection needs to be based on frequency band characteristics:
Radiated Immunity (RS) and Bulk Current Injection (BCI) testing are core methods for verifying the electromagnetic immunity of vehicle electronic devices. They simulate spatial electromagnetic fields and wiring harness conducted interference respectively, forming a complementary testing system.
Automotive power systems face various transient interferences during operation, such as load dump, ignition noise, and fast transients caused by switching operations. These interferences may cause DC-DC converter output voltage fluctuations, logic errors, or even functional failures, posing significant threats to system stability.
| Test Type | Standard Reference | Test Parameters |
|---|---|---|
| Transient Conducted Immunity | ISO 7637-2 | Pulse 1, 2a, 2b, 3a, 3b |
| Inductive/Capacitive/Direct Capacitive Coupling Clamp Method | ISO 7637-3 | Slow pulse 2a, Fast pulse 3a/3b |
| High Voltage System Testing | ISO 7637-4 | Pulse A and Pulse B test scenarios |
| Electrostatic Discharge (ESD) | ISO 10605 | Contact discharge and air discharge |
EMC testing of vehicle-mounted DC-DC products forms a logical closed loop of "EMC testing - product reliability - brand competitiveness" through construction, creating a complete chain from technical compliance to market value transformation. Its core value is reflected in multi-dimensional strategic support.
Meet international and domestic standards such as CISPR 25, IEC 61000-6-3, GB/T 18655, etc.
Prevent electromagnetic noise from high-voltage systems from interfering with low-voltage control systems
Adapt to 5G/C-V2X communication technology applications, high-voltage system popularization in new energy vehicles, and expansion of intelligent connected functions
To ensure the electromagnetic compatibility (EMC) compliance and technical competitiveness of vehicle-mounted DC-DC products, it is recommended that enterprises adopt a systematic path of "forward design + precise testing".
