Entering the second quarter of 2026, exports of energy storage products remain robust. Whether large-scale energy storage power stations or portable outdoor power supplies, energy storage devices are gradually expanding from industrial scenarios into daily life of ordinary consumers. The efficient and stable operation of these devices relies on a critical category of components: power devices. Inside energy storage systems, MOSFETs and resistors serve as core switches and auxiliary measuring components respectively. Their selection directly determines system efficiency, heat management and long-term reliability.

Core Modules of Energy Storage Devices

An energy storage device generally consists of several core internal modules: Battery Management System (BMS), inverter, DC-DC converter and various protection circuits. The BMS monitors battery status and manages charging and discharging processes. Inverters convert direct current into alternating current for output, while DC-DC converters adjust power between different voltage levels. Collaborative operation of these modules realizes energy storage and release. Power devices are embedded across all modules, and their operating conditions directly govern overall system performance.

MOSFETs in Energy Storage Systems

MOSFETs serve as the primary power switching components in energy storage systems. They are categorized into medium-low voltage MOSFETs and high-voltage MOSFETs according to voltage ratings and application scenarios.

In main switching applications of BMS, MOSFETs control the on-off status of battery strings. Such applications demand low on-resistance: lower resistance translates to smaller conduction loss and easier heat dissipation. Taking Heketai HKTG90N03 as an example, it features 30V withstand voltage, 90A current rating and 3.8mΩ on-resistance, fully meeting switching requirements of main BMS circuits. For higher current-carrying demands, HKTG150N03 maintains 30V withstand voltage while upgrading current rating to 150A and reducing on-resistance to 2mΩ, making it ideal for large-scale battery packs.

DC-DC conversion circuits in energy storage systems require multi-stage voltage conversion, including stepping down high battery-pack voltage to low auxiliary power supply and converting input charging voltage to load output voltage. Medium-low voltage MOSFETs are widely used as power switches in such circuits. Unlike BMS main switches, DC-DC circuits prioritize a balance between switching speed and conduction loss. Operating under high-frequency switching, device designers must strike an optimal trade-off between energy efficiency and heat generation.

At inverter output stages, high-voltage MOSFETs undertake key switching tasks in small and medium-power energy storage inverters. Heketai HKTD7N65 boasts a 650V withstand voltage that delivers sufficient voltage margin for inversion output. Combined with 7A current rating and TO-252 package, it fits mainstream power-grade inverter designs. These high-voltage MOSFETs withstand voltage stress from AC output while maintaining low switching loss.

Resistors in Energy Storage Systems

If MOSFETs act as primary switches in energy storage systems, resistors function as behind-the-scenes critical components.

Distributed in current sampling circuits, protection circuits and discharge loops, resistors are inconspicuous yet directly affect system measurement accuracy and safety. For current sampling, BMS tracks real-time charging and discharging current of battery packs to calculate state of charge and execute balancing strategies. Sampling precision largely depends on resistor performance. Alloy resistors commonly adopted in energy storage systems feature low temperature coefficient and outstanding stability, keeping consistent resistance across wide temperature ranges and delivering accurate current signals to BMS. Energy storage systems impose extremely strict safety requirements.

Functions including overcurrent protection, overtemperature protection and short-circuit protection all rely on power resistors. In short-circuit protection loops, power resistors limit peak fault current and delay response time for subsequent protective components. These resistors require high power endurance and stable performance to avoid failure under abnormal operating conditions.

Conclusion

With years of technical expertise in power devices, Heketai provides comprehensive component solutions for energy storage applications. For medium-low voltage MOSFETs, HKTG90N03 and HKTG150N03 adopt PDFN5×6 packages, with on-resistance of 3.8mΩ and 2mΩ respectively, suitable for BMS main switches and DC-DC conversion circuits. On the high-voltage side, HKTD7N65 adopts TO-252 package, and its 650V/7A specifications fully satisfy voltage stress requirements of inverters. Meanwhile, Heketai’s resistor portfolio covers current sampling and high-power scenarios, supporting matching component selection for energy storage protection circuits.

For engineers developing energy storage products, understanding functions and parameter specifications of various power devices lays the fundamental groundwork for stable system efficiency and long-term reliability.