Series of articles catalog
1. Component foundation
2. Circuit design 3. PCB design 4. Component soldering 6. Program design
Recently, I have seen netizens have a great misunderstanding about IGBT anti-parallel diodes, and I feature this article to tell you the truth.
This picture is a three-phase two-way inverter circuit. In the picture we can see the usage of anti-parallel diodes.
When the input DC voltage is higher than the back EMF of the load, it is an inverter circuit that converts the DC power into an AC power with a peak value equal to (or less than) the DC voltage (the waveform is determined by the driving signal. The common driving signal is SPWM sinusoidal pulse width modulation. That is, sine wave alternating current).
When the input DC voltage is lower than the reverse electromotive force of the load, it is a three-phase rectifier bridge. At this time, the reverse charging current from the load flows back to the DC power supply through the rectifier bridge to realize electric braking.
Why encapsulate the two together. In fact, most of the IGBT applications are the circuits shown in the figure above (two-phase, three-phase or more phases). Packaged together can reduce costs, simplify circuits, and increase reliability. When the IGBT is used alone, the reverse diode usually does not work, which does not affect the circuit design. Just be careful that the motor may malfunction when the wires are connected reversely.