How to change the polarity of DC generator terminal voltage?

Circuits that change the positive and negative polarity of DC generator terminal voltage can be seen everywhere in real life, such as children's electric toy cars, which can move forward or backward, so it is necessary to adjust the positive and negative polarity of DC motor voltage. The implementation method is as follows:

1. adopt professional DC motor drive chip. For example: L298N

2. This is realized by bridge circuit design. Four transistors or MOS transistors are connected to a bridge circuit, and the positive-negative conversion is completed by controlling these four transistors. Pay attention to leave a certain dead time when two pairs of transistors are turned on, otherwise the positive and negative electrodes will be short-circuited.

The above two methods plus PWM can also complete the speed regulation function, haha, very simple.