Wind Turbine Project: IGBT Shunt Tutorial

Well, the linear shunt did not work well. It could have been from wire-wound resistors causing an excessive voltage spike, or the linear model did not share the current equally, causing a cascade failure. I think it was the voltage spike. Anyway, I developed a different shunt controller using just one IGBT chip rated at 600V/75A. The chip is hit with a gate driver chip (TL4429) and opens fully. This is a bang-bang controller, hitting the dump load with the full current. A built in hysteresis and delay prevents dangerous oscillations that would destroy the chip. So far the unit has worked well, using a 30 ohm/4kw load.

The design has a high static load of 25w when the wind turbine is putting out 2.3kw. It is only 1w when it is putting out 50w. This is a consequence of the design conditions. The unit needs to be able to divert power to the shunt when the turbine voltage exceeds 234v. This usually will happen if the grid goes down. I wanted the unit to be self-contained and not rely on the 120v household voltage. The shunt controller needs to divert power if the grid is on or off; it is the threshold voltage that is truly important.

In order to do this I needed a steady voltage source for the IC chips. It had to be steady over a range of 0-350v. The 2300 ohm resistor going to the 18v regulator accomplishes this task. The regulator had to be able to deliver enough milliamps to the 4429 gate drive chip to rapidly charge the IGBT gate capacitance to take the chip through saturation as quickly as possible. Conducting 9A @ 235v could easily destroy the chip if it lingered in the linear region for too long.

Here is the basic schematic. The actual unit has an LED tied in with the load. The fan is set up to run when the load is active, cooling the unit. Head sinks take care of the warming at lower voltages which do not trigger the dump load.

So far this topology has worked well without any failures.


Cooling fans are set to engage when unit activates. Aluminum bars serve as heatsinks.

There are two chains of 8 120R/250W Dale resistors.


-----> Click here if you want to read how to make circuit this circuit and develop your own printed circuit boards.