An uninterruptible power supply (UPS) system is widely used as a backup power supply for various important infrastructure during a short-term power outage, which is quite a mature application. However, the rapid development of silicon carbide (SiC) technology has brought new design concepts to the UPS system and improved its operational efficiency. This article will show you the development of the UPS system and the power MOSFET solution introduced by onsemi.
UPS provides a stable power supply for infrastructure
An uninterruptible power supply (UPS) system is widely used to protect many applications such as telecommunications, data centers, hospitals, industrial facilities, etc., and provides power for critical components in these systems. In addition to being a backup power supply when the power grid is a short-term power cut, the UPS system also provides a power filter function to ensure reliable voltage supply.
UPS system usually has two main configurations: offline and online. The offline system is connected in parallel with the main supply line and provides support for the main line. The difference is that the online system is located on the main supply line and can provide better performance and power quality, common in higher power or more demanding applications.
Infrastructure such as telecommunications, data centers and hospitals need to achieve efficient and reliable power at the lowest possible cost, and the UPS system plays an important role in it. Compared with traditional silicon-based power devices and other options, adopting SiC-based technology to design UPS systems will greatly improve the energy efficiency of these infrastructures.
Recently, SiC transistors have been adopted in the UPS power stage, and the efficiency has been significantly improved to over 98%. Such high efficiency is attributed to using wide band gap (WBG) semiconductors such as SiC, which can work in higher temperatures, frequencies, and voltages than traditional silicon-based devices such as MOSFET and IGBT. UPS based on SiC has better heat dissipation, so it can work at higher temperatures. UPS using SiC devices will be smaller, lighter and more efficient.
Provide a complete SiC power semiconductor solution
onsemi has long-standing expertise and leadership in power management and conversion, helping customers worldwide develop a UPS system with cutting-edge technology that maximizes load power quality and reliability and reduces the cost of ownership. With SiC, SiC/Si hybrid and IGBT module technology, onsemi provides advanced discrete SiC MOSFET, IGBT and medium voltage SJ MOSFET, as well as versatile gate driver, power conversion, sensing and protection IC series, which can help meet various requirements of low, medium and high power UPS design.
onsemi developed SiC module that consists of SiC MOSFET and SiC diode, and SiC MOSFET and SiC driver by using SiC technology. onsemi's SiC MOSFET features robustness and durability, with 10x dielectric breakdown field strength, 2x electron saturation velocity, 3x energy band gap, and 3x thermal conductivity. All of onsemi's SiC MOSFETs include AEC-Q101 and PPAP compliant options designed and certified specifically for automotive and industrial applications. Its system advantages include maximum efficiency by reducing power loss, higher power density, higher operating frequency, higher operating temperature, reduced EMI and, most importantly, reduced system size and cost.
Ideal for high power applications, onsemi's high-performance GaN, IGBT, MOSFET, galvanic isolation, optical isolation and SiC MOSFET drivers are designed for high system efficiency, high reliability, short propagation delay, etc. The ideal performance characteristics of these gate drivers enable them to meet the requirements of automotive, industrial, cloud power supply and computing applications. onsemi's SiC related solutions will be described as follows.
SiC modules for improving efficiency or power density
The NXH006P120MNF2 SiC module introduced by onsemi is a half-bridge or two-PACK SiC module with two 6 mΩ 1200V SiC MOSFET switches and an F2 package thermistor. SiC MOSFET switches use powerful M1 planar technology and are driven by 18V-20V gate drivers. They improve reliability through planar technology and lower die thermal resistance, operate at 20V to reduce losses, and are compatible with other modules if operated at 18V. The NXH006P120MNF2 SiC module can be applied to DC-AC conversion, DC-DC conversion and AC-DC conversion. Common end products include UPS, energy storage system, electric vehicle charging station and solar inverter.
The other NXH010P120MNF1 SiC module is a two-PACK half-bridge topology that containing a 10 mΩ 1200V SiC MOSFET half-bridge and an NTC thermistor in the F1 module. The NXH010P120MNF1 SiC module has a recommended gate voltage of 18V-20V, with low thermal resistance, Thermal Interface Material (TIM) or no TIM option, which can improve RDS(ON) at higher voltage, resulting in improved efficiency or increased power density. It is a flexible solution with a highly reliable thermal interface, and can be used in AC/DC conversion, DC-AC conversion and DC-DC conversion. The end products include an electric vehicle charger, energy storage system, three-phase solar inverter and UPS.
Easy-to-mount integrated module with higher output power
onsemi's NXH400N100H4Q2 SiC hybrid module is a power integrated module (PIM), which contains an I-type NPC stage, including 100 A, 1200 V SiC diodes for the neutral point clamps, 400 A, 1000 V IGBTs for the outer IGBT, and 400 A, 1000 V IGBTs for the inner IGBTs. An onboard thermistor is included. The NXH400N100H4Q2 SiC hybrid module has a low thermal impedance baseplate module, soldering and press-fit options, and an optimized combination of 1000V low VCE(SAT) IGBT and 1200V SiC diode, which can be used for DC-AC conversion, featuring easy module mounting and higher output power, flexible support for different manufacturing processes, excellent efficiency and thermal loss under normal and reactive power conditions. It is an IGBT solution with output power higher than 1200V and can be applied to DC-AC conversion of 1500V system. The end products include a 1500V decentralized utility solar inverter and a 1500V energy storage system.
The NXH300B100H4Q2 Si/SiC hybrid module is a three-channel flying capacitor boost module, each channel containing two 1000 V, 100 A IGBTs, two 1200 V, 30 A SiC diodes, and two 1600 V, 30 A bypass diodes. The module also includes an NTC thermistor, with a low thermal impedance baseplate module and soldering and press-fit options, supporting 1000V low VCE (SAT) fast switching IGBT, and optimized combination of 1200V SiC diode, which can be used for flying capacitor boost stage. It has easy module mounting and higher output power can flexibly support different manufacturing processes, has excellent efficiency and thermal loss, and is an IGBT solution with output power higher than 1200V. The NXH300B100H4Q2 Si/SiC hybrid module can be applied to the MPPT boost stage, and the end products include a 1500V decentralized utility-scale solar inverter and energy storage system.
onsemi's NXH200T120H3Q2 Si/SiC hybrid module is also a PIM that containing a split T-type neutral-point clamped three-level inverter consisting of two 200A/1200V half-bridge IGBTs with inverse diodes, two neutral point 100A/50V SiC diodes, two 150A/650V neutral point IGBTs with inverse diodes, two half-bridge 150A/1200V rectifiers, and a negative temperature coefficient (NTC) thermistor. The NXH200T120H3Q2 Si/SiC hybrid module has low VCE(SAT) fast switching IGBT, combined with SiC diode at the neutral point, low thermal impedance baseplate and solder pin, which has the highest power density and efficiency, high robustness under short-term high power conditions, can be mounting without press-fit tools, and can be applied to DC-AC stage. The end products include solar inverters, UPS and energy storage systems.
The NXH80T120L2Q0 is a PIM containing a T-type neutral point clamped (NPC) three-level inverter consisting of two 80 A/1200 V half-bridge IGBTs, 40 A/1200 V half-bridge diodes and two 50 A/600 V NPC diodes to form an IGBT with two 50 A/600 V NPC diodes. The module also contain an on-board thermistor. The NXH80T120L2Q0 is a high-speed 1200V and 650V IGBT with low VCE(SAT), with and without pre-applied TIM, and press-fit pins and solder pins for improved power efficiency, simpler mounting process, and a wider selection of module mounting processes. It can be applied to solar inverters, UPS inverters, and the end product is solar string inverters.
Development evaluation board for improving development efficiency
onsemi has also launched a variety of development evaluation boards for developing power systems. SEC-3PH-11-OBC-EVB is a three-phase onboard charger (OBC) PFC-LLC platform, which can realize the most advanced system efficiency through AEC-Q SiC power devices and drivers. The system boasts a high-performance SiC MOSFET 1200 V, 80 mΩ (NVHL080N120SC1), a SiC MOSFET 6A gate driver (NCV51705) and a 650 V, 30 A SiC diode (FFSB3065B-F085). The kit is designed in a modular approach and equipped with a user-friendly GUI (graphical user interface), which is helpful to evaluate SiC devices in OBC applications. LLC system is driven by embedded software in voltage or current control modes, which can be used as a learning environment for three-phase AC/DC power conversion.
SEC-3PH-11-OBC-EVB can be used to develop AC/DC three-phase PFC full bridge (voltage source inverter), DC/DC LLC full bridge, executable software FOC (field-oriented control), CC (constant voltage) and CV (constant voltage), with an input voltage of 195-265 Vac, DC bus current of max 735 Vdc, an output voltage of 200-450 Vdc, an output current of 0-40A, a sampling frequency of up to 400 Hz, and state-of-the-art proven achievable efficiency (> 95%) that facilitate system evaluation tests and measurements. It is proprietary for establishing three-phase PFC/LLC topology systems, applicable to OBC, electric vehicle charging, and three-phase AC/DC conversion.
Another SECO-GDBB-EVB is the baseboard of the gate driver plug-and-play ecosystem, which can be used to compare the dynamic performance and functions of different gate drivers and technologies (such as NCP51705, FOD8334 or NCV57000). In addition, the suite helps to select an optimized gate resistance (Rg) for the end application. SECO-GDBB-EVB can accommodate up to six different daughter cards with gate drivers, provide them with common PWM control signals, and provide the equal working conditions for reliable comparison between the gate drivers. The switching frequency (10-200 kHz) and duty cycle can be manually adjustable, and the frequency range can be fine-tuned and extended through BNC connectors. There are multiple test points on the circuit board for voltage and current measurement.
SECO-GDBB-EVB has an input voltage of 15 V ± 1 V. It has an onboard PWM generator with adjustable frequency and duty cycle, which can be used for BCN connectors generated by external PWM, and has isolation voltages of SiC and IGBT gate drivers (4 rails +15 V/-9 V and 2 rails +20 V/-4 V) and selected daughter cards. Various mini boards can be used for testing gate drivers out of the box. Examples are NCP51705SMDGEVB, SECO-NCD5700-GEVB, SECO-NCD57000-GEVB, SECO-NCP51530HB-GEVB, SECO-NCP51561BADWR2G-GEVB, which can be applied to the comparison of different gate driver technologies and facilitate the selection of gate resistance, and are used in industrial and automation fields.
Conclusion
UPS system is an important backup power supply for the important infrastructure of many applications such as telecommunications, data centers, hospitals, industrial facilities, etc. SiC technology can improve the operation efficiency of UPS and is the best solution for the new generation UPS design. onsemi offers complete SiC devices and modules solution and provides a convenient software and hardware development environment, which will be the best choice for developing a UPS system.