Vehicle-mounted DC -DC converter
As usual, we'll start by looking at DC/DC converters and their role in new energy vehicles from a product /system perspective.
The image below shows the DC/DC converter from Xinrui Technology . Xinrui Technology and Fute are leading companies in OBC and DC/DC converters.
Traditional gasoline-powered vehicles are equipped with a low-voltage generator assembly, which charges the vehicle's 12V or 24V low-voltage battery and provides all low-voltage power to the entire vehicle. In new energy vehicles, the generator is replaced by a DC/DC converter, which draws power from the vehicle's power battery (400V/800V) to charge the vehicle's 12V or 24V low-voltage battery and provide all low-voltage power to the entire vehicle.
Product Features:
Technology Platform: G5/G6
Input voltage: 30V~1500V
Output voltage: 12V/24V/36V/48V
Power range: 800W~6kW
Conversion efficiency: 96%+
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Indicators of on-board DC/DC converters
The main technical specifications of DC-DC converter components are as follows: (Compiled from Zhineng Automotive)
Power rating : Different vehicle classes often have significant differences in configuration, leading to variations in the dynamic power requirements of the 14V system. Following the modular development concept, different power ratings are selected to match different vehicle classes. After electrical balancing, higher power ratings are generally used to cover different platforms.
Conversion efficiency : Efficiency is a crucial objective, determining the heat dissipation method of the entire unit and the lifespan of the entire component. Efficiency is typically evaluated using an efficiency curve corresponding to the output current . The lower half of the figure below shows the losses of different units.
Volume, weight, and power density: The integrated design of components currently has stringent requirements on the size and weight of components, which are all installed in large systems, making the design requirements quite high; the current mainstream is to integrate DC/DC and OBC, or DC/DC and OBC, and PDU to improve power density and reduce size;
Heat dissipation methods: Similar to most power electronic components, at around 2KW, there are two methods: active air cooling and liquid cooling.
Cost: The cost requirements for components are very strict, so topologies like the full-bridge MOSFETs require more MOSFETs and are therefore often abandoned.
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Onboard DC/DC converter topology
Previously, when introducing the DC-DC module in charging piles , we provided an in-depth introduction to PFC and DC-DC power supply topologies. (Link: High-Power Charging Pile Series)
Although automotive DC-DC converters have lower power outputs, their operating principle is similar. The following material comes from a special presentation given by Wang Zhengshi of the School of Electrical Engineering at Zhejiang University on 21st Century Power Supply Network, which introduces different topologies and their respective advantages and disadvantages.
TI C2000-based reference design
Image source: Texas Instruments official website
Image source: ST Automotive WeChat Official Account
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BAIC Three-in-One (Small Three-Electric) Main Chip List
BAIC Small Three-Electric Integration Main Component List
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Teardown photos of GAC (Fute) vehicle-mounted DC/DC converter
Excerpted from the WeChat official account "Drive Vision," this refers to the DC/DC converter supplied by Fute to GAC Group.
Input voltage 200VDC~480VDC, output voltage 12~15VDC, output current 0~220A, water cooling method, the main control chip is TI's C2000 TMS320F280049;
