Application of new switching power supplies
Into the 21st century, with the continuous development of power electronics technology, high-frequency switching power supply with its high efficiency, high performance, low weight, small size, in more and more widely expanding occasions also gained an increasingly wide range of applications, DC switching regulated power supply is used more and more widely. In some industrial applications need to provide AC and DC voltage and current sources, and requires a wide range of regulation, ripple is small. If you use more than one single function power supply equipment, the volume and weight will increase a lot, not economic, and can not meet the requirements of the work. Therefore, our company specialises in researching and developing a set of power supply solutions.
This power supply system adopts switching power supply technology and digital control programme, it can be used as AC voltage source, DC voltage source, AC current source and DC current source, the output adjustment range is 1~250V as voltage source, the adjustment range is 1~30A as current source, the working 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, the lower part is the current source part, each part adopts two-stage structure, the AC input is rectified and filtered, and then converted to DC/DC first, and then output through the inverter. The DC/DC adopts a half-bridge circuit to provide a stable DC bus voltage and isolate the input and output stages. The inverter section uses a conventional full-bridge inverter circuit, which is suitable for larger power applications. The output is filtered by a two-stage LC filter to remove 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, which is especially obvious when the bus voltage is relatively high. Therefore, the common mode suppressor Lc1 is connected in series between the two stages to isolate the mutual interference, and Lc2 and Lc3 are connected between the output terminal and the load, which are similar to Lc1, and are used to inhibit the high-frequency common mode component through the load. The difference is that the voltage source adopts full-bridge rectification for the DC/DC front stage, and the current source adopts full-wave rectification.
However, the inverter input current is not a true DC current, in addition to the DC component, but also contains double the output frequency of the AC component and high-frequency component. For the current source in the output current is the maximum, these high-frequency components will be very large, need to bus to provide a large high-frequency ripple current, so while trying to increase the electrolytic capacitance, should be used more high-frequency performance of superior capacitance. Not only can meet the requirements of the rear high-frequency ripple current, but also reduce the impact of the rear high-frequency components on the front stage.
