These diodes protect the mosfets from current spikes

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: when the MOSFETs are switched off. These diodes are only needed if the internal MOSFET diodes are not sufficient for dissipating the BEMF current. Bidirectional control of a BDC motor requires a circuit called an H-bridge. The H-bridge, named for its schematic appearance, is able to move current in either direction through the motor winding. To understand this, the H-bridge must be broken into its two sides, or half-bridges. Referring to Figure 8, Q1 and Q2 make up one half-bridge while Q3 and Q4 make up the other half-bridge. Each of these half-bridges is able to switch one side of the BDC motor to the potential of the supply voltage or ground. When Q1 is turned on and Q2 is off, for instance, the left side of the motor will be at the potential of the supply voltage. Turning on Q4 and leaving Q3 off will ground the opposite side of the motor. The arrow labeled IFWD shows the resulting current flow for this configuration. FIGURE 8: The capacitors (C1-C4) are optional. The value of these capac...
View Full Document

This note was uploaded on 01/29/2014 for the course AA AA taught by Professor Aa during the Winter '10 term at ENS Cachan.

Ask a homework question - tutors are online