Providing higher energy efficiency in inverter applications, this IGBT module

However, this shift has led to a rapid increase in demand for electricity, which has put a great deal of pressure on the power grid. Despite their high energy efficiency, applications such as electric vehicles, data centers, and heat pumps still require a lot of energy to operate.

New renewable energy sources such as solar, wind, and wave energy are gaining popularity and are gradually becoming mainstream . Only applications that use renewable energy completely can be considered truly “clean” applications.

The solar energy market has been developing for many years and is relatively mature. According to a report by Fortune Business Insights, the current solar energy market size is estimated to be US$273 billion and is expected to grow to US$436 billion by 2032. In 2023, North America's solar energy market share exceeded 40%.

Solar power generation is growing rapidly. According to the International Energy Agency (IEA), in 2022, electricity generated by solar energy increased by 26% over the previous year to 1,300 TWh. This means that solar power generation has surpassed wind power to become the largest source of renewable electricity.

Solar photovoltaic (PV) panels generate direct current (DC), while the grid requires alternating current (AC), so central PV inverters are an integral part of large grid-connected installations. All the energy generated by the PV panels goes through the inverter, so inverter efficiency plays a major role. Although solar energy is inexhaustible, poor conversion efficiency means that the amount of energy delivered to the grid is very limited. The energy wasted in the process is converted into heat, which poses a serious challenge because many solar installations are often located in sunny and hot environments, such as deserts.

Cost is also a very important consideration, which directly affects the electricity bills of consumers and the profitability of power companies. To achieve higher power, many central inverters use multiple conversion modules in parallel, the specific number of which is determined by the power rating of each module. The higher the power capacity of each module, the fewer modules are required, which can reduce costs.

While electric vehicles have made great strides, CAVs have been slow to make the transition to electric propulsion. Larger in size, they consume more fuel and produce more emissions per trip, and although they only make up 2% of all vehicles, they account for 28% of total transportation greenhouse gas emissions. While the electrification of commercial passenger vehicles (such as buses) has begun to take off, most large trucks, construction machinery and agricultural vehicles (such as tractors) still rely on diesel. Now, things are starting to change. Electric truck sales (pure electric and hybrid) are expected to increase from the current 5% to 40%-50% by 2030 to meet strict zero-emission regulations in global markets such as the European Union, China and California in the United States.

Compared to fossil fuel commercial vehicles, electric commercial vehicles have a simpler structure and fewer moving parts. With the same load capacity, electric vehicles are smaller, more reliable, and have lower maintenance-related costs. With battery costs significantly reduced, the total cost of ownership of electric CAVs is already lower than that of internal combustion engine (ICE) vehicles.

Similar to solar applications, efficiency is also a key requirement for electric CAVs . Each vehicle has a limited battery capacity, and the more efficient the conversion process in the inverter is, the longer the vehicle can travel. Or less power is required to travel the same distance.

Given our future reliance on solar power and electric CAVs, reliability will naturally become very important.

In high power applications such as three-phase solar photovoltaic inverters, the three-level active neutral point clamped (ANPC) converter is a common topology. This multi-level topology is specifically designed to improve the performance and efficiency of the system.

The normal neutral point clamped (NPC) converter uses a diode to connect the neutral point of the DC link capacitor to the output. In the ANPC configuration (Figure 1), the clamping is performed by the switch, which improves control, reduces switching losses and improves efficiency, and can correspondingly reduce the need for heat sinking measures, thus helping to achieve a smaller and lower cost solution.

The topology is arranged in such a way that the voltage stress on the individual switches is reduced, thus improving reliability. In addition, ANPC can achieve waveforms that are beneficial to the grid.

Figure 1: ANPC converters can be easily constructed using building blocks

By paralleling multiple power modules, such as ON Semiconductor's QDual 3 IGBT modules, design engineers can create high-performance three-level active neutral point clamped modules with system output powers of up to 1.6 MW to 1.8 MW.

Figure 2: QDual3 IGBT module

The QDual 3 module integrates the next generation 1200 V Field Stop 7 (FS7) IGBT and diode technology to provide improved performance for high power applications. FS7 technology significantly improves conduction losses compared to previous generations.

Figure 3: FS7 technology enhances key performance parameters

In the FS7 IGBT process, the narrow trench terrace brings low VCE(SAT) and high power density, while the proton implantation multiple buffers ensure robustness and soft switching characteristics (Figure 2). ON Semiconductor's medium-speed FS7 device has a VCE(SAT) as low as 1.65V, suitable for motion control applications; while its FS7 fast product has an EOFF of only 57 µJ/A, which is ideal for high-power applications such as solar inverters and CAVs.

Figure 4: FS7 IGBT has smaller size and higher power density

Innovative FS7 technology enables the chip size in the new QDual3 module to be 30% smaller than the previous generation (Figure 3). This miniaturization, combined with advanced packaging, allows for a significant increase in maximum current rating. In motor control applications operating at temperatures up to 150 degrees Celsius, the QDual3 has an output power range of 100 kW to 340 kW, which is about 12% higher than other products currently on the market.

Reliability is key for solar and CAV applications, so the way modules are constructed and tested is critical. For example, many similar solutions currently use wire bonding to fix the terminals, while ON Semiconductor chooses to use ultrasonic welding to weld the modules. The latter helps increase current carrying capacity, provides a better heat dissipation path, and is more robust than the former (Figure 4).

Figure 5: Ultrasonic welding reduces temperatures and increases reliability

This approach improves electrical conductivity, thereby reducing power losses and increasing efficiency. It also reduces operating temperatures, increases mechanical rigidity, and improves the overall reliability of the module.

The dedicated QDual 3 half-bridge IGBT module NXH800H120L7QDSG is suitable for central solar inverters, energy storage systems (ESS), uninterruptible power supplies (UPS); while the SNXH800H120L7QDSG is suitable for CAVs. Both devices are built on FS7 technology with improved VCE(SAT) and EOFF, which reduces losses and improves energy efficiency.

Currently, if a 1.725 MW inverter is designed using 600 A IGBT modules in an ANPC/INPC architecture, a total of 36 modules will be required. However, if the new NXH800H120L7QDSG and SNXH800H120L7QDSG with a rated operating current of 800 A are used, the number of modules required in the design will be reduced by 9. Accordingly, the size, weight and cost of the design will be saved by 25%. This is very valuable for both solar applications and CAV applications, because the weight reduction and efficiency improvement will increase the vehicle's mileage.

Figure 6: Greater current capability enables systems to be built using fewer modules

The modules include an isolated baseplate for thermal management and an integrated NTC thermistor, and support direct mounting of the modules to a PCB via solderable pins, using an industry-standard layout, making it easy to upgrade existing designs to the new QDual3 technology.

All of ON Semiconductor’s QDual3 modules undergo rigorous reliability testing, with reliability levels exceeding other similar devices on the market. Our humidity testing requires products to withstand 960V bias for up to 2000 hours, while similar devices only withstand 80V bias for 1000 hours. Vibration testing is critical for CAV applications, and our products are tested at 30G peak/10G RMS conditions for up to 22 hours to meet AQG324 requirements. Other devices are tested at vibration levels as low as 5G for as short as 1 hour.

The use of renewable energy is increasing around the world, and the power grid is under tremendous pressure. Solar power generation has matured and will surpass wind power in 2022 to become the main source of renewable electricity.

Although fossil fuel-powered vehicles remain a major source of pollution, the electrification of CAVs is progressing steadily and has already shown initial results.

New semiconductor technologies such as ON Semiconductor's FS7 enable the development of low-loss, high-power devices to meet the efficiency and reliability needs of these areas. Based on this technology, ON Semiconductor's new QDual3 device uses a compact package to achieve high power density and excellent energy efficiency. Well-welded terminals and certification testing that exceeds other devices in the industry help ensure the robust performance of QDual3 devices.

The new generation NXH800H120L7QDSG and SNXH800H120L7QDSG modules have a current capability of up to 800 A, which can reduce the number of modules required for inverter design by 25%, and can further simplify the design, reduce its size, weight and cost.

This is undoubtedly a significant development, and ON Semiconductor will continue to explore the high-performance potential of FS7 technology and strive to launch more modules that exceed existing standards to meet the growing needs of the solar industry and CAV manufacturers.

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