Many types of industrial machines and electronic devices in multiple industrial applications—such as motor drives, PV inverters, UPS systems, and modular multilevel converters—require an auxiliary (aux) power supply for reliable operation. These systems often get their main power from a high-voltage line, typically from 300 V up to 1000 V. But smaller parts of the system such as control circuits, sensing circuits, and cooling fans only need low voltage power, approximately 5 to 48 volts.
Because these auxiliary power supplies are required to operate from a wide input voltage range, due to use of a common DC link or bus, the system requires a way to convert high voltage to low voltage safely and efficiently. Often single switch flyback topology is selected for this type of low-power DC-DC power conversion. A single-switch fly-back converter (a simple and inexpensive circuit that uses only a few parts to turn high voltage into low voltage) provides a simple structure, the lowest component count, and low cost.[1] [2]
Now, by using a newer type of electronic switch called a SiC MOSFET (a high-performance semiconductor switch made of silicon carbide), engineers can make these aux power supplies simpler, cheaper, and more reliable —especially for machines that work over a wide voltage range. Refer to the example schematic in Figure 1.
Figure 1. Single-switch flyback converter system using SiC MOSFET.
Applications
Some applications where SiC MOSFETs provide benefits:
- Motor Drives
- Photovoltaic (PV) inverters
- Battery Energy Storage Systems (BESS)
- Uninterruptible Power Supply (UPS) Systems
- Modular Multilevel Converters
Figure 2. Equipment where SiC MOSFETs can simplify aux power system design and lower costs.
Benefits
SiC MOSFETS are able to withstand high voltage while offering a sufficient amount of headroom. Operating at 1Ω Rds(on), they support up to 60 W of output power. They maintain operating performance even at high temperatures (up to 175° C). High frequency operation reduces the size of components including the magnetics and lower device capacitances with SiC Fast Body Diodes reduces switching losses.
Highlighted Product
Luminus offers high-quality SiC power products under the brand Analog Power Conversion Electronics (APC-E), including this SiC MOSFET:
- AMR1K0V170E1 – SiC MOSFET, 1700 V, 1 Ω, TO-247
APC employs state-of-the-art manufacturing processes conforming to the latest industry standards. All products are designed in the U.S. and built in the Philippines ensuring some of the shortest lead times in the industry.
You can purchase samples of Luminus Power Semiconductor products here. Our authorized distributors include Avnet Electronics, Mouser and Digikey.
Learn more about other applications that can benefit from SiC power products from APC:
Increasing Power Supply Efficiency with SiC Boost Diode and MOSFETs
Improving Solid State Motor Efficiency with SiC Three-Phase Motor Driver Inverters
Increasing the Efficiency of Bidirectional Converters with SiC Power Devices
For more information, please email apc-e@luminus.com
REFERENCES:
[1] Ray Ridley; Fly-back Converter Snubber Design; Switching Power Magazine; 2005
[2] Texas Instruments; UCCx8C4x BiCMOS Low-Power Current-Mode PWM Controller; Application Note; 2017
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