Technical information

Easy Automotive Modules

Evaluation Kit EASYKIT AUX DRIVES (FS50R07W1E3_B11A)

Experimental Results

Application Note 32 AN2012-10

Evaluation Kit EASYKIT AUX DRIVES (FS50R07W1E3_B11A)

6.2 Short Circuit Tests

Short circuits can be considered as most critical events for an inverter. Two different types of short circuits

were tested with the Evaluation KIT. Short circuit I is a short circuit close to the power module (e.g. on the

power connectors) and thus has a low inductance. The short circuit II appears in the system if e.g. the motor

windings generate a short.

The following tests were performed at 25°C, where higher short circuit currents and faster switching

characteristics (voltage overshoot) is achieved compared to Tj=150°C.

6.2.1 Short Circuit I (low inductance)

The power terminal of the phase output was directly connected to the DCL+ terminal. A current probe was

inserted in the short circuit cable to measure the currents of this short circuit (IL). The equivalent circuit

during this test is shown in Figure 22.

Figure 22 Equivalent circuit of the short circuit I test. The device under test is the right low-side

switch.

Figure 23 shows the measured waveforms of the IGBT (see Vce and Vge) and the short circuit current (IL).

The IGBT turns-on at 0 us. After approx 0.4 us the current is high enough that the IGBT desatures (Vce

voltage rises to high values despite the IGBT is still turned on). This desaturation is detected quite fast in the

gate driving circuit, which turns-off the IGBT at approx 1.5us. The turn-off overvoltage with <100V is

relatively low. All measured values were within the specification of the F4-50R07W1E3_B11A power module.

Supply

System

<450V

Short

Circuit

Vce

Vge