**Author: Zhongda Li, New Product Introduction Manager at United Silicon Carbide Company**
**Commitment to Wide Bandgap Devices**
Wide bandgap (WBG) devices such as silicon carbide (SiC) and gallium nitride (GaN) are currently hot topics in the power electronics industry. These technologies promise to reduce the size of wireless charging systems, power converters, and more. However, while they show great potential on paper, real-world performance often depends on how well these materials can be harnessed.
To understand WBG devices, it's important to first grasp what makes them different from traditional silicon (Si) devices. In semiconductors, electrons exist in two energy bands: the valence band and the conduction band. To allow current flow, electrons must transition from the valence to the conduction band, which requires a certain amount of energy. This energy difference is called the bandgap. In wide bandgap materials like SiC, this bandgap is significantly larger—3.2 eV for SiC compared to 1.1 eV for Si. This means that more energy is required to excite electrons into the conduction band, resulting in higher breakdown voltages and better thermal performance.
Because of this, SiC can operate at higher temperatures and has better thermal conductivity than silicon. These properties make WBG devices ideal for high-power, high-temperature applications where reliability and efficiency are crucial.
Initially, SiC was used primarily in simple diodes. But with advances in material technology, more complex devices like junction field-effect transistors (JFETs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and even bipolar transistors have become available. For example, a SiC JFET with a vertical trench structure offers much lower on-resistance compared to a GaN HEMT with a lateral structure.
Although SiC JFETs are normally "on" at zero gate voltage, when paired with a Si MOSFET in a "co-source" configuration, they form a hybrid device that is compatible with standard Si MOSFET gate drives while retaining the advantages of wide bandgap technology.
When comparing SiC and GaN, there are several key differences. While GaN has higher electron mobility and potentially faster switching speeds, its thermal conductivity is lower than SiC, limiting its power density. Additionally, SiC devices are more mature in terms of manufacturing and cost, especially at 650V and above. GaN is still emerging in the market and is expected to gain traction in areas like data centers, electric vehicles, and photovoltaics.
The supply chain for SiC is well-established, with products readily available from major distributors. In contrast, GaN is not yet mainstream. Market data suggests that by 2025, the total WBG market will reach $3.5 billion, with GaN accounting for only about $500 million.
In industrial systems, SiC has a clear advantage due to its ability to withstand overvoltage conditions, such as those caused by inductive loads. Manufacturers have demonstrated that SiC can handle high-voltage stress reliably, whereas GaN is typically rated only to a maximum voltage without additional protection.
Another key difference is packaging. SiC devices are commonly packaged in TO-247 or TO-220 packages, making them easy to replace existing MOSFETs. GaN, on the other hand, is often packaged in smaller, surface-mount formats that limit its use to new designs.
Designers also face challenges with EMI and dV/dt control when using fast-switching devices like SiC and GaN. Even though both can achieve high dV/dt values, stray capacitance can lead to large current spikes, requiring careful design considerations.
Currently, SiC cascode devices are available up to 1200V with currents up to 85A and on-resistance as low as 30mΩ. Some advanced SiC devices can even handle over 3.5kV. GaN devices, meanwhile, are typically limited to 650V with similar on-resistance but offer faster switching speeds.
Looking ahead, while IGBTs and traditional MOSFETs will continue to dominate the market, the adoption of WBG devices is expected to grow rapidly. The future will likely see different WBG technologies dominating various market segments based on their strengths and costs.
In high-power applications, SiC’s robustness under transient short-circuit and overvoltage conditions makes it an excellent choice. Its self-limiting behavior during high current events and superior thermal management further enhance its reliability.
For example, in a bridgeless totem pole PFC circuit using SiC JFETs, continuous conduction mode can be achieved, improving efficiency and reducing EMI. A 1.5kW, 230VAC circuit has demonstrated an impressive 99.4% efficiency.
Manufacturers like United Silicon Carbide Inc have shown that SiC components can withstand 1000 hours of operation under avalanche conditions at 150°C, proving their durability and reliability.
As the power electronics industry evolves, wide bandgap devices are set to play a pivotal role in enabling next-generation, high-performance systems. Whether in industrial, automotive, or consumer applications, the benefits of SiC and GaN are becoming increasingly evident.
Industrial UPS
Industrial UPS is a specialized power protection system designed to provide backup power to critical industrial equipment in the event of a power outage or fluctuation. It is commonly used in industries such as manufacturing, oil and gas, chemical processing, telecommunications, and data centers.
Performance:
Industrial UPS systems are built to withstand harsh environmental conditions and provide reliable and stable power to sensitive equipment. They offer high levels of protection against power disturbances like surges, spikes, sags, and voltage fluctuations. These UPS systems typically have a high fault tolerance and can provide instantaneous power transfer during a power outage, minimizing downtime and preventing damage to equipment.
Industrial UPS systems can deliver power in different forms, including online, line-interactive, and offline. Online UPS systems provide continuous power protection by continuously converting AC power to DC and then back to AC. Line-interactive UPS systems regulate voltage fluctuations while being connected to the AC power source. Offline UPS systems are the simplest and provide basic power backup during outages.
Application Scenarios:
1. Manufacturing: Industrial UPS systems are crucial in manufacturing plants where downtime can result in significant financial losses. They protect critical equipment such as robotic systems, programmable logic controllers (PLCs), and control systems, ensuring uninterrupted operation and preventing data loss.
2. Oil and Gas: In the oil and gas industry, UPS systems are used to safeguard critical equipment like pumps, compressors, and control systems. They ensure uninterrupted power supply, which is crucial for maintaining safety and preventing accidents in hazardous environments.
3. Chemical Processing: Industrial UPS systems are essential in chemical processing plants where precise control of equipment is necessary. They protect sensitive instruments, control systems, and data acquisition systems, ensuring uninterrupted operation and preventing loss of valuable data.
4. Telecommunications: UPS systems play a vital role in the telecommunications industry, protecting critical communication infrastructure such as servers, switches, routers, and data centers. They provide uninterrupted power supply, ensuring continuous connectivity and preventing service disruptions.
5. Data Centers: Industrial UPS systems are widely used in data centers to protect servers, storage systems, and networking equipment. They provide backup power during outages, preventing data loss and ensuring continuous operation of critical services.
Uninterruptible power supply, Industrial-grade, Reliable, Power protection, Backup power
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