Applications of New - Type Switching Power Supplies
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 a wide range of applications due to their high efficiency, high performance, low weight, and small size. DC switching power supplies are becoming more and more widely used. In some industrial settings, it is necessary to provide AC and DC voltage and current sources, with a wide range of regulation and low 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 the work. Therefore, our company has conducted professional research and developed a set of power supply solutions.
This power system adopts switch power technology and digital control scheme, which can be used as 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. The operating frequency is 0-400Hz. The output can be selected.
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 AC input rectification and filtering, it first goes through DC/DC conversion and then outputs through the inverter. The DC/DC adopts a half bridge circuit to provide stable DC bus voltage and isolate the input stage and output stage. The inverter part adopts a conventional full bridge inverter circuit, which is suitable for high-power applications. The output uses two-stage LC filters to filter out high-frequency ripples. Lc1, Lc2, and Lc3 are common mode suppressors. The high-frequency switching action 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, similar in function to 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 AC and high-frequency components that are twice the output frequency. When the output current of the current source is , these high-frequency components will be very large, requiring the bus to provide a large high-frequency ripple current. Therefore, while maximizing the electrolytic capacitor, capacitors with superior high-frequency performance should be used more often. Not only can it meet the requirements of high-frequency ripple current in the rear stage, but it can also reduce the impact of high-frequency components in the rear stage on the front stage.
