Application of New Switching Power Supply
Since the beginning of the 21st century, with the continuous development of power electronics technology, high-frequency switching power supplies have been increasingly widely used in more and more widespread occasions due to their high efficiency, high performance, low weight, and small size. DC switching regulated power supplies are also being used more and more widely. In some industrial applications, it is necessary to provide AC and DC voltage and current sources, with a wide adjustment range and small ripple. If multiple functional single power supply devices are used, the volume and weight will increase significantly, which is not economical and cannot meet the requirements of work. Therefore, our company has professionally researched and developed a set of power supply solutions for safety.
This power supply system adopts switch power technology and digital control scheme, which can be used as an AC voltage source, DC voltage source, AC current source, and DC current source. As a voltage source, the output regulation range is 1-250V, and as a current source, the regulation range is 1-30A, with a working frequency of 0-400Hz. Output selectable.
Main circuit structure
The main circuit of the power supply is divided into two parts: the upper part is the voltage source part and the lower part is the current source part. Each part adopts a two-stage structure. After the AC input is rectified and filtered, it is first transformed into DC/DC and then output through the inverter. DC/DC adopts a half bridge circuit to provide stable DC bus voltage and isolate the input and output stages. The inverter part adopts a conventional full bridge inverter circuit, which is suitable for high-power applications. The output uses a two-stage LC filter to filter out high-frequency ripple. Lc1, Lc2, and Lc3 are common mode suppressors. The high-frequency switching actions of the front and rear stages of the voltage source can easily cause mutual interference between the two stages, especially when the bus voltage is relatively high. Therefore, a common mode suppressor Lc1 is connected in series between the two stages to isolate their mutual interference. Lc2 and Lc3 are connected between the output terminal and the load, and their function is similar to that of Lc1, used to suppress high-frequency common mode components passing through the load. The difference is that the voltage source front-end DC/DC adopts full bridge rectification, while the current source adopts full wave rectification.
However, the input current of the inverter is not the true DC current. In addition to the DC component, it also contains an AC component and a high-frequency component that are twice the output frequency. When the output current of the current source is *, these high-frequency components will be large, and the busbar needs to provide a large high-frequency ripple current. Therefore, when increasing the electrolytic capacitor as much as possible, more capacitors with superior high-frequency performance should be used. Not only can it meet the requirements of high-frequency ripple current in the later stage, but it can also reduce the impact of high-frequency components in the later stage on the previous stage.
