Problem Simulating IGBT Desaturation with IR2127

[Van12]

Hello,

I am attempting to simulate Voltage desaturation for an IGBT as a short circuit protection scheme. I have imported the spice model into MultiSim and created the component. The IGBT I am using is an IRGPF40F. I want the 2127 to output low state to the IGBT gate when the current reaches 6A or the High voltage supply spikes to 650V.

I have included the IR2127 spice models, screen shot of the schematic editor and the application note that details how modify the 2127 for desaturation voltage monitoring for easy reference.

Initially, the collector of the IGBT is connected to ground. When 12V is applied to the IN pin of the 2127, the HO pin provides 14.6V to the resistor on the IGBT gate. The voltage appearing at the CS pin is 208mV, below the 250mV threshold. The FAULT pin at this point reports 15uV, which makes no sense to me. When switch J3 is toggled to the 650V supply, the HO pin provides 218mV and 230mV appears at the CS pin and the FAULT pin report 1.88nV.

The behavior of this chip is not making sense to me. Can someone please provide insight?

[johnsold]

I have not used that exact device bu thave used the IRS2011. It does not have a fault\ line.

The datasheet specifies that fault is an open drain connection. Your circuit needs a pull up resistor from fault to Vcc.

Be aware that models which use lots of switches, as this one does, can have convergence problems.

Lynn 

[Van12]

Thank you for catching that mistake. I appreciate your advice.