From the types of power switches you use to the layout of your printed circuit board (PCB), numerous design decisions will affect the robustness of your high-power inverter designs. In this Power Hour webinar, Staff Product Manager, John Wilson, and Sr. Staff Applications Engineer, Long Nguyen, describe the key issues and solutions to consider when designing high-power inverter systems. They introduce the Si828x isolated gate drivers and explain how they can benefit your high-power designs. The following highlights are some key takeaways from the presentation.
One of the first decisions to make when designing your high-power inverters is the type of power switch you will use. Power switches have unique capabilities and requirements, such as voltage limits, temperature ranges, and operating frequencies, that will drive numerous design decisions for your high-power inverters, including which type of gate driver to use. The four main types of power switches are:
Working voltages are another essential factor to consider. Designers must evaluate the maximum voltages the system will be exposed to under normal conditions and ensure that the gate drivers and power switches can meet these power requirements. For the gate driver, the working voltage rating will exceed maximum expected peak voltages. For switches, a rule of thumb is that the maximum expected voltages should be less than 80% of the device family’s voltage rating.
Gate drivers and power switches have critical protection needs that must be addressed in the design. For example, undervoltage issues generate heat and efficiency loss. Overvoltage can cause switch damage. Fortunately, these issues can be mitigated with solutions such as desaturation detection, using a Miller clamp to prevent switch parasitic turn-on, and careful PCB layout techniques.
There are also application dependencies to consider. For example, a stable, high-power application, such as a steady-running industrial motor inverter, may not need much protection. In contrast, a dynamic application, such as an EV traction inverter, may require extensive system protection.
PCB board layout is also an important consideration when designing a power electronic circuit because it determines the power circuit's performance, efficiency, and reliability. A well-planned PCB layout minimizes parasitic inductance and capacitance and improves reliability and efficiency.
A final consideration is determining how to supply power to the secondary side of a half-bridge device. This task can be accomplished discreetly or in an integrated fashion.
As you design your high-power inverters, look for power switch technologies and gate drivers appropriate to the working voltages required by your system application. Consider the critical protection needs and choose gate drivers that can provide solutions accordingly.
Silicon Labs offers a full spectrum of solutions with our Si828x isolated gate drivers. An integrated dc-dc converter within these devices simplifies layout and provides each driver with its own power supply, which translates to reduced noise and inductances and a more compact and smaller PCB.
The Si8285 has all the apps and features of the Si828x family (desaturation detection, Miller clamp, etc.), as well as an industry-leading noise immunity of 125 kV/us. We also have a robust reference circuit that enables adjusting various parameters based on the type of power switch you are using.
In addition to the Si828x series, we offer an extensive isolated gate driver product family that is suitable for inverters. Altogether, these devices offer a broad range of benefits, from power robustness to extensive flexibility.