- Keywords: lithium battery, DC/DC converter
- Summary: Modern energy storage systems using lithium-ion batteries can provide excellent performance, but each battery must be closely monitored to ensure proper charging and avoid battery imbalance, overcharging, deep discharge or critical temperature.
Modern energy storage systems using lithium-ion batteries can provide excellent performance, but each battery must be closely monitored to ensure proper charging and avoid battery imbalance, overcharging, deep discharge or critical temperature. This requires a separate, isolated power supply voltage control circuit for each unit or unit array. For battery arrays with nominal voltages up to 48V, standard industrial DC/DC power converter modules that provide 500V or 1600V isolation barriers can be used to generate this power supply voltage.
But for higher power systems connected to AC power supply and providing hundreds of kilowatt hours or even several megawatt hours of energy storage capacity, the voltage on the battery array can reach 600-800V, and a solution with higher isolation barriers is required.
The customer is looking for solutions that meet the requirements of overvoltage category III and 4kV isolation barriers. Each battery monitoring circuit requires a 30W converter, and hundreds of converters are connected in parallel. The total leakage current on the converter is another challenge.
Low isolation capacitance enhances anti noise capability
P-DUKE has a series of medical power converters with 5kV isolation barriers, even higher than the required 4kV. For this project, MPD30-24S12 is selected, which can generate the necessary 12V/30W power supply voltage from the public 24Vdc bus.
The input and output capacitance of a typical industrial 30W DC/DC power converter is up to 1500pF. When up to 200 converters are connected in parallel, the total capacitance between the battery unit (connected to the AC power grid through the charger) and the 24V bus can reach 300 nF, resulting in AC leakage current exceeding 20 mA. The current exceeding 10mA may cause serious electric shock and accident.
The input and output capacitance of MPD30-24S12 is only 20pF, the total capacitance of 200 converters in parallel is only 4nF, and the leakage current is less than 1mA.
This very low capacitance also avoids transient or any noise from the AC/battery side cross converter coupling to the sensitive communication signal of the central battery management system.
Through this solution, the requirements of 4kV isolation and low leakage current have been solved.
For the communication in the whole installation, the central BMS controller uses a Wifi router and is powered by a 25W 53V power supply through Ethernet. According to the final installation, the power supply voltage can be generated by the 230Vac main power supply or the internal 24Vdc bus. For 230Vac, TSD30 series converters can be used. It also offers a Din rail version for easy installation in the controller rack.
Success stories
The RCD30 series converter can generate 53V voltage from the 24Vdc bus and adjust the output from 54V to 53V. It also has an integrated radiator for easy cooling
Architecture diagram
Example 1:
BMS circuit Solution-
Example 2:
54Vdc/25W is used for PoE WiFi router Solution-
Large battery storage systems benefit from the application of P-DUKE products:
MPD30/MPD30W series is a series of 30W DC/DC power converters with enhanced 5000Vac isolation voltage, which can meet the requirements of medical applications. They have different input voltage ranges and provide single or dual outputs. This series meets the 2MOPP standard, and the clearance and creepage distance are 8mm. This makes them suitable not only for medical equipment, but also for other applications requiring high isolation and extremely low input and output capacitance.
The TSD30 series is a ready to use AC/DC solution for Din rail applications. Like the RCD30W series, it provides different output voltages and installation options for various applications.
Original link: https://www.pduke.com.cn/sc/news_detail5_136.htm
MPD30/MPD30W： https://www.pduke.com/sc/product_list322.htm
TSD30: https://www.pduke.com/sc/product_list353.htm
RCD30W: https://www.pduke.com/sc/product_list257.htm
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