Microcontroller drives H bridge to power a permanent-magnet dc motor

摘要

A traditional method of driving a low- to medium-power permanent-magnet dc motor involves using four MOSFET or bipolar transistors in an H-bridge configuration. For example, in Figure 1, the motor connects between collector pairs C{sub}1 and C{sub}2 and C{sub}3 and C{sub}4. Turning on diagonally opposite transistor pairs Q{sub}1 and Q{sub}3 or Q{sub}2 and Q{sub}4 steers current through the motor and allows for reversal of its direction of rotation. However, this method requires that each of the four transistors receive its own control input. Depending on the motor's voltage requirements, the upper two drive signals may require electrical isolation or a level-shifter circuit to match the microcontraller's output-voltage limitations.