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How can I insert dead time into a PWM circuit?
One option is to use RCD delay circuits (resistor in parallel with a diode, feeding a capacitor hooked to the input of your gate driver). This circuit will delay turn on of your switch but not turn off so you’ll have deadtime inserted in hardware.
How to calculate the dead time to incorporate in the game?
Dead time is to prevent shoot through i.e. both MOSFETs conducting appreciable current at the same time. That’s good because you are almost there. Should I add the turn off delay of both these to get my dead time?
Why does unipolar complementary switching need dead time insertion?
This mode needs dead time insertion (DTI) between the top and bottom switches to avoid any phase short-circuit, this will be explained more later. Unipolar complementary switching leads to lower switching losses and current ripple.
When does the third quadrant loss occur in a FET?
The third quadrant loss in a FET occurs when the current flows from the source to drain while the FET gate is low (FET is off). In silicon FETs, there is a parasitic body diode in the structure which typically
What happens if you switch a PWM multiple times?
This effect, even for short a duration causes large current spikes, which increases thermal output, and when switching a few thousand times a second quickly wears out the MOSFET. Worst case you blow up your whole circuit.
Are there different types of PWM control schemes?
The first of the two being the PWM control scheme. There are 4 main variants of PWM control schemes for a 3 phase BLDC controller. I originally was just under the naive impression that there was one standard way to perform the functionality, and was no so surprised to find that “there is more than one way to skin a cat.”
Which is better bipolar or independent PWM control?
However, from a back-EMF “sensorless” perspective, the bipolar complementary switching is the better choice as explained above. The complementary or independent approaches refer to the relationship of the two signals controlling one of the phases. The independent approach applies to the PWM only on one side of the phase.