AC parameter regulated power supply and its suppression of harmonics
1、 Overview
With the wide application of power electronics, on the one hand, it has brought huge economic benefits, on the other hand, it has also brought about a decline in power supply quality, affecting many electrical equipment that are very sensitive to power quality. Experts agree that most of the failure causes of microelectronic instruments and computer systems are caused by power supply quality problems, such as impact, low power factor, Voltage sag, harmonic distortion, power failure There are many methods to solve these power quality problems, such as flicker and interference signal voltage, with significant differences in investment costs. AC parameter stabilized power supply, also known as stabilized voltage transformer (CVT), is one of the more effective methods to solve power interference and is receiving increasing attention. Currently, it has been widely used in communication base stations, aerospace, nuclear industry, railways, hospitals, banks, financial securities, public security, and other industrial and mining enterprises and institutions in large, medium-sized Minicomputer, computer network numerical control system, program control system, analytical measuring instruments, metrological inspection, photocopier, medical equipment and other equipment are used together, and good results have been achieved.
2、 The basic principle and characteristics of AC parameter regulated power supply
1. AC parameter regulated power supply, also known as Constant Voltage Transformers, is abbreviated as CVT.
2. The main differences between constant voltage transformers and ordinary transformers are:
① Functionally, although it separates the primary and secondary windings of an iron core, it does not follow the proportional relationship between input and output voltage and the number of turns of the primary and secondary windings, and the output voltage does not remain constant with changes in input voltage.
② The magnetic shunt core of a constant voltage transformer has saturation and unsaturated zones in each section.
③ Parallel capacitors and compensation windings with boost resonance.
3. Main characteristics of technical parameters
① Simple structure, no control components, only composed of two individual components.
② Simple structure, high reliability, and average time between failures are among the highest among various AC regulated power supplies.
③ High voltage stability and wide voltage stabilization range. From the source voltage effect, it can be seen that when the input voltage changes by ± 20%, the output voltage changes by ± 1.5%, and when the input voltage changes by ± 30%, the output voltage changes by ± 3.5%. If the ratio of rated output load to actual load is appropriately selected, the voltage stabilization range can be extended to a good state, so it is particularly suitable for areas with high voltage fluctuations in the power grid.
4. Anti interference performance: CVT is a transformer that integrates voltage stabilization, isolation, and transformation. The input and output are completely isolated, and it has good bidirectional suppression and attenuation effects on pulse interference signals in the power grid. At the same time, it has good anti-interference ability against surge impact, instantaneous sudden change, instantaneous flicker, electrostatic lightning, and other disturbances in the power grid.
5. The reaction time is fast, within 40ms.
6. Overload automatic protection
When the output power exceeds the rated value, the output voltage automatically decreases to ensure that the electrical equipment is not damaged even if the output load is short circuited. After the load short circuit is lifted, the output voltage will be automatically restored; After starting with load or power grid outage, the output will not generate overvoltage, if there is twice the voltage
