The existence of battery technology is the foundation for the completion of APC UPS uninterruptible power supply systems. Since French scientist Prandt made lead-acid batteries with lead electrodes in 1859, lead-acid batteries have been developed and improved for more than a hundred years and have become a widely used chemical battery in the world. Due to their low cost, large capacity, safety and reliability, lead-acid batteries are widely used in communication Railway, military, electric vehicles, photovoltaic power generation and other fields have universal applications, gradually becoming indispensable equipment in social consumption and human life. Battery charging is essentially a process of energy conversion. In practice, battery charging installation is a charging power source, which is controlled by a certain algorithm to ensure that the output voltage and output current match the battery charging curve. At present, there are three commonly used charging power sources: phase controlled power supply, linear power supply, and switching power supply.
(1) Phase controlled power supply is compared to traditional power supply. It directly rectifies and filters the mains power to output DC, and changes the conduction phase angle of the thyristor rectifier to control the output voltage of the power supply. The transformer used in phase controlled power supply is a power frequency transformer, which has a large volume, resulting in the phase controlled power supply itself being bulky and inefficient. Moreover, this type of power supply has poor dynamic response and low reliability. At present, phased power supplies have a tendency to gradually be phased out.
(2) Linear power supply is another common type of power supply that can be continuously controlled through series adjustment tubes. The power regulator of a linear power supply operates in the amplification region, and the current passing through it is continuous. Due to the high power loss on the adjustment tube, it is necessary to use high-power adjustment tubes and assemble large volume radiators.
(3) The research on switch mode power supplies has a relatively short history. Relevant research began in the mid-1960s, and DC/DC converters were developed at that time, laying the foundation for the development of switch mode power supplies. In the 1970s, rectifiers using high-frequency conversion technology were introduced, which directly rectified and inverted AC power without passing through a power frequency converter, and then rectified and filtered into DC power. With the development of power electronics technology and automatic control technology, especially the emergence of new high-frequency switching devices such as high-power high-voltage field-effect transistors, the switching frequency of power converters has been greatly improved, reducing the volume and weight of transformers in power converters, thereby greatly reducing the volume and weight of switching power supplies. The initial low-frequency switching power supplies in switching power supplies have been developed into high-frequency switching power supplies, with higher switching frequencies and more perfect control technology. In the design of battery charging installation, it is precisely because the performance of switching power supplies is becoming more and more perfect that they have gradually become the first choice for the design of charging power main circuits.