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Electric Vehicle Charging Station Categories and Latest Standards (Power Boosted to 800kW)
DC charging is significantly faster. In September 2023, China's Ministry of Industry and Information Technology released two electric vehicle charging standards (GB/T20234.1-2023 and GB/T20234.3-2023), raising the maximum charging current from 250A to 800A and the charging power to 800kW, while ensuring compatibility between new and old charging interfaces.
Increasing the range of electric vehicles requires larger battery capacity, while reducing charging time demands high-output charging stations. For example, a 360kW charger uses nine 40kW power modules. Typically, unidirectional chargers employ efficient three-phase Vienna rectifiers and LLC circuits, whereas bidirectional chargers use three-phase B6-PFC combined with dual active bridge circuits to enable bidirectional energy transfer, fulfilling the needs of EVs for grid and home power supply. In this process, the design and optimization of magnetic components, alongside power components, are crucial to ensure the efficient, safe, and reliable operation of the charging system.
Electric Vehicle Charging Station Categories and Latest Standards (Power Boosted to 800kW)
DC charging is significantly faster. In September 2023, China's Ministry of Industry and Information Technology released two electric vehicle charging standards (GB/T20234.1-2023 and GB/T20234.3-2023), raising the maximum charging current from 250A to 800A and the charging power to 800kW, while ensuring compatibility between new and old charging interfaces.
Increasing the range of electric vehicles requires larger battery capacity, while reducing charging time demands high-output charging stations. For example, a 360kW charger uses nine 40kW power modules. Typically, unidirectional chargers employ efficient three-phase Vienna rectifiers and LLC circuits, whereas bidirectional chargers use three-phase B6-PFC combined with dual active bridge circuits to enable bidirectional energy transfer, fulfilling the needs of EVs for grid and home power supply. In this process, the design and optimization of magnetic components, alongside power components, are crucial to ensure the efficient, safe, and reliable operation of the charging system.
Strategies for Optimizing Magnetic Components to Address High Frequency and Heat Dissipation
Electric vehicle power modules use a modular architecture. In an 800kW ultra-fast charging system, 26 groups of 30kW power modules are required. Due to space constraints, the modules need to be compact, but in a confined space, heat dissipation is challenging. This leads to higher module temperatures, which can cause component failure and reduce the reliability of the charging system.
The importance of magnetic components in high-power charging technology cannot be overlooked. Optimization and design can be approached from technical aspects such as magnetic core materials, increasing frequency, winding methods, and thermal management.
Optimizing and designing magnetic components from cores to windings is crucial for achieving 800kW high-power ultra-fast charging. The saturation flux density and permeability of the core material determine the amount of flux the core can handle under specific magnetic field strengths. High permeability materials easily saturate at low magnetic field strengths, and high currents cause a sharp increase in flux density, leading the core into saturation. High-frequency operation generates strong magnetic field variations, increasing the risk of core saturation. Additionally, rising operating temperatures reduce permeability, making cores more prone to saturation. When inductance decreases, filtering effectiveness weakens, common mode noise increases, transformer conversion efficiency deteriorates, and the stability and reliability of the entire charging system are affected.
↓↓Click below to download the document and learn how to optimize thermal management and saturation issues through core and winding process improvements.
Key to High-Power Charging Performance
Saturation Current and Temperature Rise in Magnetic Components
The saturation flux density and permeability of core materials determine the magnetic flux a core can handle under specific magnetic field strengths. High permeability materials saturate easily at low magnetic fields, and high currents can rapidly increase flux density, leading to core saturation. High-frequency operation causes strong magnetic field changes, also increasing saturation risk. Additionally, rising operating temperatures can reduce permeability, making the core more prone to saturation. This drop in inductance weakens filtering effects, increases common mode noise, reduces transformer efficiency, and affects the stability and reliability of the entire charging system.
Definition of Saturation Current (Isat)
Inductors typically contain a core, especially power inductors, which exhibit magnetic saturation. When the magnetic field intensity reaches a certain level, the increase in magnetic flux density slows down and eventually saturates. Concurrently, the core's permeability (μ) significantly decreases, leading to a substantial drop in inductance and a loss of its normal current suppression capability. Saturated current is defined as the rated current where the inductance value drops by 20-30%.
The definition of temperature rise current (Irms)
Due to the inherent parasitic DC resistance in inductors, the internal temperature of the inductor increases with the current during operation. Generally, the current at which the self-heating of the inductor does not exceed 20°C or 40°C is considered the temperature rise current, which is also the rated current for the application of the inductor. This ensures that the inductor will not be damaged by overheating when operating within this current range.
Magnetic saturation current and temperature rise current can be verified and tested through DC superposition. The MICROTEST DC Bias Current Test System offers a maximum current output of 640A and a frequency response of 100Hz to 10MHz. It provides current sweep analysis to examine the extent of inductance value reduction due to current impact, precisely verifying magnetic saturation and temperature rise characteristics.
Key to High-Power Charging Performance
Saturation Current and Temperature Rise in Magnetic Components
The saturation flux density and permeability of core materials determine the magnetic flux a core can handle under specific magnetic field strengths. High permeability materials saturate easily at low magnetic fields, and high currents can rapidly increase flux density, leading to core saturation. High-frequency operation causes strong magnetic field changes, also increasing saturation risk. Additionally, rising operating temperatures can reduce permeability, making the core more prone to saturation. This drop in inductance weakens filtering effects, increases common mode noise, reduces transformer efficiency, and affects the stability and reliability of the entire charging system.
Definition of Saturation Current (Isat)
Inductors typically contain a core, especially power inductors, which exhibit magnetic saturation. When the magnetic field intensity reaches a certain level, the increase in magnetic flux density slows down and eventually saturates. Concurrently, the core's permeability (μ) significantly decreases, leading to a substantial drop in inductance and a loss of its normal current suppression capability. Saturated current is defined as the rated current where the inductance value drops by 20-30%.
The definition of temperature rise current (Irms)
Due to the inherent parasitic DC resistance in inductors, the internal temperature of the inductor increases with the current during operation. Generally, the current at which the self-heating of the inductor does not exceed 20°C or 40°C is considered the temperature rise current, which is also the rated current for the application of the inductor. This ensures that the inductor will not be damaged by overheating when operating within this current range.
Magnetic saturation current and temperature rise current can be verified and tested through DC superposition. The MICROTEST DC Bias Current Test System offers a maximum current output of 640A and a frequency response of 100Hz to 10MHz. It provides current sweep analysis to examine the extent of inductance value reduction due to current impact, precisely verifying magnetic saturation and temperature rise characteristics.
