钠电池 PACK 的主动均衡和被动均衡有什么区别？

What are the differences between active balancing and passive balancing of sodium-ion battery PACK?

主动、被动均衡是 PACK 两类主流均衡技术，在能耗、效率、硬件成本、适用场景四大维度差异明显。一工作原理：被动均衡依靠功率电阻将高压电芯多余电能转化热量耗散；主动均衡借助电容、电感、变压器储能元件把富余电量转移至低压电芯循环复用。二均衡效率：被动均衡不足 60，电能全部浪费发热；主动均衡效率 90 以上，电量循环利用大幅减少能量损耗。三硬件造价：被动均衡电路简单，BMS 成本低廉，适配小型低成本路灯、外卖电动车 PACK；主动均衡电路板元器件增多，成本上浮 30~80。四均衡速度：被动均衡电流小，抹平大压差耗时久；主动均衡均衡电流大，快速修复压差。五适配场景：被动均衡用于低附加值小型储能；主动均衡专供工商业兆瓦储能、电网调频、船舶等高循环高价值项目，降低电站度电损耗。

Active balancing and passive balancing are two mainstream PACK balancing technologies with obvious differences in four dimensions: energy consumption, efficiency, hardware cost and applicable scenarios. First working principle: passive balancing dissipates excess electric energy of high-voltage cells into heat via power resistors; active balancing transfers surplus electricity to low-voltage cells for recycling by energy storage components such as capacitors, inductors and transformers. Second balancing efficiency: passive balancing efficiency is below 60 with all electric energy wasted as heat; active balancing exceeds 90 and recycles electricity to greatly reduce energy loss. Third hardware cost: passive balancing circuits are simple with low BMS cost, suitable for small low-cost street lamp and food delivery vehicle PACKs; active balancing circuit boards add components with 30~80% higher cost. Fourth balancing speed: passive balancing carries small current and takes long time to eliminate large voltage difference; active balancing delivers large current to rapidly repair voltage gaps. Fifth applicable scenarios: passive balancing applies to low-value small energy storage; active balancing is exclusively for high-cycle high-value projects such as industrial megawatt storage, grid frequency regulation and ships to reduce power loss per kilowatt-hour of power stations.