Charging circuit using transformer step-down method

Charging circuit using transformer step-down method

A transformer is used to step down the voltage, and then it is rectified and filtered to form a low-voltage DC charging circuit , as shown in the figure. This method has a simple structure
. low cost. The output voltage of the rectifier and filter circuit is not stable enough and has large ripples. There are two main problems. First, because the secondary voltage of the transformer is directly related to the grid voltage, when the grid voltage fluctuates, it will inevitably cause secondary voltage fluctuations, which will make the output of the rectifier filter circuit unstable . Second, because the rectifier filter circuit There is always internal resistance. When the load current changes, the voltage across the internal resistance also changes, thus making the voltage obtained by the load (ie, the output voltage ) unstable. In order to provide a more stable DC power supply, a voltage stabilizing circuit needs to be added after the rectifier and filter.