Energy Storage Systems (ESS) have become crucial for enhancing energy application efficiency. By storing the energy generated by photovoltaic systems, homes and businesses can still use stored energy when the photovoltaic system is operating at low efficiency, such as at night or on cloudy days, or even be fed back into the grid. This article will introduce the architecture and applications of ESS, along with the features of solutions offered by Murata.
ESS combine with renewable energy systems to store excess energy
An Energy Storage System (ESS) is a system designed to convert electrical energy into other forms for storage and then convert it back to electrical energy when needed. ESS can be worked with renewable energy systems such as solar and wind to store excess energy and provide stable power during adverse weather conditions or peak electricity demand.
ESS is also utilized to balance the energy supply and demand in microgrids, enhancing system stability and reliability. It serves as a backup power source, ensuring continuous operation during emergencies. ESS can charge during periods of low energy consumption and discharge during peak demand, effectively shifting energy consumption and reduce peak electricity costs. Additionally, ESS may also use in electric vehicles, offering efficient energy storage to extend driving range and enhance vehicle performance.
The architecture and applications of an Energy Storage System (ESS) can be adjusted based on different requirements and environments. Generally, an ESS architecture includes energy storage components, power converters, control systems, system cooling, and protection.
Energy storage components can consist of batteries and supercapacitors. In generally, the core of ESS is typically the battery, and common types include lithium-ion batteries, cobalt lithium batteries, nickel lithium batteries, and others. These batteries store electrical energy for later use. Additionally, supercapacitors also can be used to achieve rapid energy discharge, handling high-power demands in transient situations.
The power converter section comprises inverters and converters. Inverters are used to convert direct current (DC) into alternating current (AC) for use in homes, industries, or the electrical grid. Converters, on the other hand, are employed to convert electrical energy into other forms, such as mechanical or thermal energy.
The control system serves as the brain of the ESS, where intelligent controllers in the system can monitor the battery status, load requirements, and grid conditions. They regulate the charging and discharging processes of the battery to ensure optimal performance and lifespan. On the other hand, an Energy Management System (EMS) can be integrated to optimize the operation of the storage system, coordinate various energy resources, and optimize the overall system efficiency.
To ensure the safe operation of the ESS, a cooling system is essential to maintain the proper temperature of the batteries and electronic components, improving efficiency and prolonging lifespan. Safety protection features include overvoltage protection, overcurrent protection, temperature protection, and more, to ensure the secure operation of the energy storage system.
Thermistor is widely used in temperature sensing and control
A Thermistor is a semiconductor device whose resistance changes with temperature. It is primarily used in the field of temperature sensing and temperature control, playing a role in temperature sensing of an ESS control system. Depending on how the resistance changes with temperature, thermistors are divided into two major categories: Positive Temperature Coefficient Thermistor (PTC thermistor) and Negative Temperature Coefficient Thermistor (NTC thermistor).
PTC thermistors exhibit an increase in resistance with rising temperature. They are mainly used for overcurrent protection, temperature switches, and self-recovery protection of heating devices. In electronic devices, when the current exceeds the rated value, the resistance value of the PTC connected in series with the protected object in the circuit rises through its own heat, which can suppress the excess current. Additionally, PTC thermistors can also function as temperature switches, PTC resistance value increases, which can trigger corresponding switch actions when the system temperature exceeds a predetermined value.
On the other hand, NTC thermistors exhibit a decrease in resistance with rising temperature. This feature can be used to monitor the temperature of electronic devices or equipment to ensure their normal operation. In some applications, NTC thermistors are employed to compensate for temperature variations in devices, maintaining stable performance.
NTC thermistors are commonly found in our daily lives, serving as temperature sensors in thermometers, air conditioners, temperature controllers in smartphones, electric kettles, irons, and current controllers in power devices. With the increasing electrification of vehicles, NTC thermistors are also increasingly used in automotive products: such as on-board battery packs, LiDAR, etc. In addition, thermistors can be widely used in various industrial and energy projects, including electric vehicle fast charging infrastructure, solar inverters, energy storage inverters and battery packs, etc.
A comprehensive thermistor product line caters to various needs and requirements
Murata offers various types of thermistors to meet the needs of ESS applications. Murata's thermistor products can be divided into two main series: NTC thermistors and PTC thermistors. The NTC thermistor series includes the NCU high-reliability application type, NCP consumer-grade (civil) application type, and NCG conductive glue mounting type, among others. The PTC thermistor series includes the PRF overheat protection type and PRG overcurrent protection type. Among them, the NCU series is the most widely used in automotive and energy projects.
Murata's NCU series is an SMD-type NTC thermistor. Because of its special structure: the external copper electrode, it brings high reliability and can be flexibly applied in various scenarios that require temperature detection, even in demanding environments. It is the main member of Murata thermistors, mainly used for temperature detection (high reliability), especially suitable for the automotive market that requires high reliability, to achieve temperature detection and temperature compensation in a wide temperature range.
DC-DC converters meeting the requirements of new energy applications
Murata also offers a series of gate drive DC-DC converters specifically designed for gate drive circuits, including IGBT, SiC, MOS, GaN, and other product lines, typically used in new energy, motion control, mobility, and healthcare solutions. These products feature ultra-low isolation capacitance of 3pF, optimized bipolar output voltage for IGBT/SiC and MOS gate drive, DC link voltage withstand up to 3KV, reliability against partial discharge, withstand dv/dt immunity can be higher than 80kV/µS at 1.6kV and other characteristics.
Murata has commercialized insulated DC-DC converters specifically designed to cope with the high frequency of next-generation GaN power semiconductors, contributing to the rapid power conversion required for various applications. The MGN1 series of 1W output DC-DC converters from Murata are designed to provide the required voltage for GaN device gate drivers.
The MGN1 series devices offer a low-profile, small footprint, surface-mount technology to provide thin solution that can be easily integrated into space-constrained systems. They also have the advantage of lightweight design, providing greater deployment opportunities. The offered output voltages include +8V, +12V, and +6/-3V.
One of the key attributes of the MGN1 series DC-DC converters is the ultra-low isolation capacitance of 2.5pF (typical value). This minimizes transient coupling on the isolated gate, preventing signal distortion and mitigating system EMI issues. The devices boast >200kV/μs common-mode transient immunity (CMTI), making them well-suited for high-speed switching GaN-based systems, ensuring the integrity of gate driver signals. With their excellent immunity to partial discharge, these converters can reliably operate under high-voltage conditions.
The Murata MGN1 series DC-DC converters support a continuous isolation barrier withstand voltage of 1.1kV. These converters have a creepage distance and clearance data of 6.5mm, and their operating temperature range of -40°C to +105°C allows them to be installed in challenging environments. At the same time, they incorporate reverse polarity and short-circuit protection mechanisms.
These new DC-DC converters can be utilized in various GaN-based applications, including electric vehicle fast-charging infrastructure, battery storage converters, smart grid implementations, solar inverters, solid-state circuit breakers, ICT and data centers, wind turbines, and motor drives.
Conclusion
The integration of energy storage systems with new energy applications can significantly enhance the efficiency of energy usage. To effectively manage, control, and ensure the safety of energy storage systems in such applications, numerous key components are required. The market for these applications holds immense potential. Murata has introduced a comprehensive range of thermistors and DC-DC converters, offering improved monitoring capabilities and energy conversion efficiency for energy storage systems. Manufacturers interested in entering this market may find it beneficial to further explore and adopt Murata's solutions.