Recently, BYD released a charging technology that subverts the industry's cognition-megawatt flash charging, which for the first time realizes the energy supplement efficiency of "charging for 4 minutes and endurance for 400 kilometers" on mass production vehicles. This article will analyze this breakthrough innovation from the three dimensions of hardware design innovation, advantages and disadvantages analysis, and future prospects.
hardware design innovation
Single gun current is limited by the interface standard (national standard upper limit 600A), so there is a physical limit of single gun charging in theory at present, but BYD has taken another path, using dual DC charging guns in parallel to realize current superposition, bypassing the single gun limit. How does that specifically achieve dual-gun megawatt charging? This requires the cooperation of charging pile hardware and vehicle-side hardware, both of which are indispensable.
The core modules of BYD double-gun super-charging pile include: power conversion system, double-gun output module, intelligent control system and communication module.
In the power system, the rectifier stage uses a three-phase VIENNA rectifier topology to convert alternating current into high-voltage direct current; the filter stage uses an LCL filter to suppress high-frequency harmonics; the DC/DC stage uses an LLC resonant converter to adjust the output voltage to adapt to different battery platforms. In order to improve energy efficiency, the rectifier stage and the DC/DC stage may both involve the key device SiC MOSFET, which has the characteristics of high temperature resistance and low conduction loss.
In the design of the dual-gun output module, an independent dual-channel design is adopted, and each charging gun corresponds to an independent DC/DC module to support dynamic power distribution. Among them, in the dual-gun flow control, the real-time PID algorithm of FPGA is used to reduce the double-gun charging current deviation and avoid the power loss caused by the impedance difference. In addition, the core liquid-cooled gun line of the overcharge is not a traditional wire, and the double-layer stainless steel liquid-cooled pipe coolant combination can effectively reduce the heat generation and support continuous high-power output.
In the intelligent control system, the processing unit monitors the voltage, current, temperature and other parameters in real time, and dynamically adjusts the charging strategy. One of the core BMS collaborates to dynamically balance battery SOC (state of charge) and temperature control requirements through AI algorithm, supporting full environment adaptation from -30 ℃ to 55 ℃.
The communication module generally supports CAN, Ethernet, 4G/5G for remote monitoring and OTA upgrade.
On the hardware of the vehicle side, the physical interface layout adopts dual charging interfaces to realize technological innovation. The battery is BYD's own flash charging blade battery. The integrated design of the battery pack and the vehicle body is realized through the internal skeleton CTB structure, which improves the structural strength and heat dissipation efficiency. Through the optimization of high nickel and low cobalt positive electrode + silicon carbon negative electrode material, the internal resistance of the battery is reduced by 50%, and 10C ultra-high rate charging is supported. The heat dissipation of the battery is particularly important during the charging process. The flash charging blade battery adopts a double-sided direct cooling plate design, which increases the heat exchange area by 100. Combined with the refrigerant phase change technology, the battery temperature is controlled in the best range of 25-35 ℃. The battery terminal uses gradient electrodes and superconducting electrolyte to shorten the lithium ion transmission path, and can also realize terminal pulse charging with intelligent BMS.
In general, BYD MW flash charging is a collaborative innovation. Through the dual-gun high-voltage interface (breaking through the power limit) and flash charging blade battery (material and structural innovation), a hardware innovation of "the same speed of oil and electricity" is constructed. Its technical path takes into account both performance and compatibility, providing the industry with an ultra-fast charging solution that can be reused on a large scale.
analysis of advantages and disadvantages
First, let's talk about advantages: from the perspective of cost-effectiveness, compared with the single gun scheme (such as the 1000A scheme), the double gun can save the cost of liquid cooling gun line, and BYD's double gun megawatt flash charging multiplexes the existing national standard interface, that is, there is no need to redevelop the new supply chain and save the cost. In terms of safety, the double gun circuit design effectively reduces the large current of single gun charging and the contactor arc risk, reduce local overheating; The compatibility consideration is also very comprehensive. The single gun mode is compatible with the common DC pile, and the 400V/800V platform can be automatically switched and adapted through DC/DC.
There are advantages, of course, the challenge is not small. From the perspective of user experience, only one charging gun was plugged in before, but now two charging guns need to be plugged in and out manually, which requires at least 30 seconds of operation time. In addition, infrastructure is a big challenge, megawatt charging requires 1250kVA transformer (ordinary fast charging pile is only 300kVA); Technically speaking, the error balance of double gun charging should lead to a lost power loss; in addition, charging in a low-temperature environment "forever" is a pain point for electric vehicles.
Future outlook
It can be said that BYD's megawatt flash charging has opened a Pandora's box in the electric era. The original hardware can still be so innovative. The future overcharging technology is bound to be more powerful. For example, if the current of a single gun is increased to 800A or even higher with the new copper alloy interface, the two guns will not be higher (the 3 guns and 4 guns will go against the weather
Summary
The core value of BYD's megawatt flash charging is to break through the physical boundary with engineering wisdom-when the industry is trapped in the zero-sum game of "high voltage vs high current", it opens up a third way through double guns in parallel. This technology is not only a parameter breakthrough in the laboratory, but also an inclusive innovation within reach of ordinary consumers. With the improvement of super-charging ecology, electric vehicles will eventually cross the energy gap and truly become the terminator of fuel vehicles.
