Compared with traditional passenger cars, electric buses have increased high-voltage and high-power electronic and electrical equipment such as DC/AC inverters, DC/DC converters, drive motors and chargers, and frequently accelerate, decelerate and downhill during their driving. At the same time, power conversion and energy feedback are required. The electromagnetic interference generated by these devices during rectification, frequency conversion and current conversion makes the electromagnetic compatibility (EMC) problem of electric passenger cars more serious. Due to the variety of electric vehicles and electric motors, the working current is large and the harness is long. The voltage and current of the on-board electrical equipment will change drastically during the work. The surge current or spike voltage can be passed through the power line, signal line and control line. Conducting interference is formed directly in the CAN bus communication network of other electrical components and vehicles; electromagnetic energy emitted by itself or the outside world (such as lightning, broadcasting stations, mobile phone base stations, etc.) can also be transmitted by vehicle antennas and lines through space propagation. Cables and holes are coupled into the in-vehicle sensitive electronic equipment, causing electromagnetic interference problems.
Because electromagnetic compatibility problems are invisible, intangible, and random, the electric bus is more prone to "unexplained" faults, affecting the normal operation and safe driving of certain functions. The current domestic EMC standards related to electric vehicles/bus vehicles are mainly: GB14023 "Limitations and Measurement Methods for Protecting Vehicle Exterior Vehicles by Radio Disturbance Characteristics of Vehicles, Ships and Internal Combustion Engines", GB/T18387 "Electromagnetic Field Radiation of Electric Vehicles" Limits and methods of measurement of broadband 9 kHz to 30 MHz and GB 18655 "Limitations and measurement methods for the protection of vehicle receivers by radio disturbance characteristics of vehicles, ships and internal combustion engines" and GB/T19951 "Electrical disturbance tests by electrostatic discharge of road vehicles" method". At present, in the "announcement" and 3C management of automobiles, electric vehicles must meet the requirements of GB14023, GB/T18387 and GB18655. Electric vehicle export certification is generally carried out in accordance with the 72/245/EEC Directive on "Radio Disturbance of Vehicles (Electromagnetic Compatibility)" or the ECER10 Regulation "On Uniform Provisions for Approval of Vehicles in Electromagnetic Compatibility" for electromagnetic compatibility of complete vehicles and components. Testing and evaluation. At present, the domestic anti-interference of the vehicle and parts is formulated with reference to IS011451 "Test method for immunity of narrow-band radiated electromagnetic energy of road vehicles" and IS011452 "Test method for electric disturbance components produced by narrow-band radiated electromagnetic energy of road vehicles". standard test.
The power system of electric buses generally adopts high voltage systems of more than 300V, including drive motors, drive motor controllers, DC converters (high-voltage DC to low-voltage DC), high-voltage battery packs, and some vehicles using high-voltage electric air-conditioning compressors. High-voltage chargers, etc., these components also generally contain low-voltage working components for controlling high-voltage switching. In addition to the power drive system, conventional components such as vehicle controllers, instruments, lights, ABS, wipers, and automatic doors of electric buses use the same low-voltage system (usually 12V or 24V) as conventional buses.
For the high-voltage component system and low-voltage component system of electric bus, the current domestic electromagnetic compatibility (EMC) standards mainly include: GB18655 "Car, ship and internal combustion engine radio disturbance characteristics for the protection of vehicle receiver limits and measurement methods", GB /T21437.2 "Electrical disturbances caused by conduction and coupling of road vehicles - Part 2: Electrical transient conduction along power lines", GB/T19951 "Electrical disturbance test methods for electrostatic discharge of road vehicles" and GB/T17619 Electromagnetic radiation immunity limits and measurement methods for electric and electronic components of motor vehicles. Because it is usually isolated inside the parts and between the high-voltage system and the low-voltage system of the vehicle, no high-voltage system is required in the conduction test in GB18655, GB/T21437.2 and GB/T17619. The high-voltage harness of the component is tested; however, in the radiation test of GB18655 and GB/T17619, the high-voltage harness and the low-voltage harness should be placed together for testing.
Electric buses have added a special component to the conventional bus. This is the charging system connected to the external power grid. The national standard GB/T18487.2 "Electrical Vehicle Conductive Charging System Connection Requirements for Electric Vehicles and AC DC Power Supply" is in the 9th. In the chapter, special requirements are imposed on the electromagnetic compatibility of the electric bus charging system; the new version of the European Directive ECE R10.04 "On the Uniform Provisions for Approval of Vehicles in Electromagnetic Compatibility" has been added to the charging of electric vehicles coupled to the grid. Test requirements for the energy storage system charging mode.
After the rapid development of electric buses in recent years, the standards for the whole vehicle have been relatively complete. However, for electric bus parts, whether it is domestic or foreign, its EMC standards are still not perfect, and are still being researched and formulated.
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