In the first quarter of this year, Littelfuse’s silicon carbide MOSFET products were successfully bid for a domestic photovoltaic system project, and the product was successfully applied to the three-phase solar inverter auxiliary power circuit. Littelfuse’s design scheme has been recognized by the market again, and a long-term cooperation opportunity has been obtained.
As a professional supplier of power control, circuit protection and sensor products and services for nearly a century, Littelfuse has been focusing on and investing in the research and development of renewable energy applications for a long time. Today, many product series such as silicon carbide, TVS diodes, temperature Sensors, IGBTs, varistors, gate drives, etc. have been adopted by global core customers, and photovoltaic inverters are one of the important applications.
From the perspective of the scheme, the photovoltaic inverter architecture is roughly divided into micro inverters, centralized inverters and string inverters. No matter what kind of solution, product reliability, cost performance and technical support are indispensable in the process of winning customers. From the perspective of technological development trends, the power of micro-inverters continues to increase; centralized inverters are easy to cause the entire system to be disconnected from the grid, which brings losses and risks to users. At present, the system integration mode of string inverters is more popular. Favored by the market, it is increasingly becoming the mainstream application architecture. In the design of string inverters, Littelfuse’s power MOSFETs, IGBTs, rectifier diodes, fast recovery diodes, gate drivers, TVS diodes, fuses, varistors, gas discharge tubes and many other products are essential in the solution. An indispensable electronic device, Littelfuse can provide high-quality products of power devices and protection devices at the same time, providing users with high power density, high reliability, and cost-effective overall solutions. .
There are several ways to get electricity in the design of the auxiliary power supply scheme of the photovoltaic system. The maximum DC voltage of a 1000 V system is about 900 V, and a 1500 V system is about 1400 V. The design of this scheme is relatively simple and the cost is low, but the disadvantage is that the DC voltage transmitted on the photovoltaic panel The voltage fluctuation is relatively large, and the reliability is relatively lacking; electricity is obtained through the grid, and the general grid side voltage is AC400~800 V. This solution has high reliability, but the design is relatively complex and the cost is relatively high. Littelfuse recommends the 1700V SiC MOSFET LSIC1MO170E0750 as the power control device for the auxiliary power supply in the inverter. Due to the cost-effective advantage of Littelfuse 1700V Sic Mosfet, some customers even use this device to cover low-voltage to high-voltage application scenarios to reduce part number management and costs.
Littelfuse Silicon Carbide LSIC1MO170E0750 Series
In addition, the work efficiency and power consumption of the inverter are also the core concerns of the solution. Taking LSIC1MO170E0750 as an example, the device is a 750 mΩ N-channel silicon carbide process MOSFET. This process makes switching speed and parasitic parameters more advantageous than traditional MOSFETs, which can improve efficiency by nearly 3% and greatly improve heat dissipation. performance. Fast switching frequency, high conversion efficiency, and high voltage capability of 1700 V make it the perfect choice for high-voltage, high-efficiency inverter applications. The device’s extremely low gate charge, ultra-low on-resistance, and output capacitance make it suitable for a variety of high-frequency switching applications.
Products are tested to the most stringent standards on the market, and helping customers’ end products meet various standards is an important consideration in Littelfuse product development. Photovoltaic product applications are mostly deployed at higher altitudes or inland with dry climate. In harsh environments such as high temperature and sandstorms, users have extremely high requirements for product reliability. Products need to meet many strict requirements in system design, testing, and verification. strict industry standards. For example, high voltage and high temperature reverse bias test (HV-HTRB), HV-H3TRB, etc. Although these limit test standards are not included in the industry mandatory standards, they will be used as the user’s internal selection reference standard to ensure the power in the photovoltaic system. The device can operate stably for a long time in extremely harsh environments. The reason why Littelfuse can pass the system test at the first time is because of its long-term investment in product quality control. The verification test process is always performed according to the limit standard, so that it can stand out in the competition.
In addition, providing customers with one-stop supply with a wide range of product series is more conducive to optimization and complete solutions, and to control costs. Littelfuse is the most comprehensive supplier of product series in the fields of power control, circuit protection and sensing in the world. , Peripheral devices, on the basis of fully considering the product advantages and the core value of the design, to provide users with the best overall solution to maximize the performance of the product. Today’s product lines used by customers in this market include power MOSFETs, IGBTs, rectifier diodes, fast recovery diodes, gate drivers, TVS diodes, fuses, varistors, gas discharge tubes and many other products. The figure below is a recommended typical application circuit diagram for reference.
Single-phase string solar inverter application
Three-phase string solar inverter application
Overvoltage protection of three-phase strings