Protective Functions And Operating Sequence; Short Circuit Protection - Mitsubishi Electric PSS**S72FT Manual

<Dual-In-Line Package Intelligent Power Module>
1200V Mini DIPIPM with BSD Series APPLICATION NOTE

2.2 Protective Functions and Operating Sequence

Mini DIPIPM has Short circuit (SC), Under Voltage of control supply (UV) and temperature output (VOT) for
protection function. The operating principle and sequence are described below.

2.2.1 Short Circuit Protection

1. General
Mini DIPIPM uses external shunt resistor for the current detection as shown in Fig.2-2-1. The internal
protection circuit inside the IC captures the excessive large current by comparing the CIN voltage generated at
the shunt resistor with the referenced SC trip voltage, and perform protection automatically. The threshold
voltage trip level of the SC protection Vsc(ref) is typ. 0.48V.
In case of SC protection happens, all the gates of N-side three phase IGBTs will be interrupted together with
a fault signal output. To prevent DIPIPM erroneous protection due to normal switching noise and/or recovery
current, it is necessary to set an RC filter (time constant: 1.5μ ~ 2μs) to the CIN terminal input (Fig.2-2-1, 2-2-2).
Also, please make the pattern wiring around the shunt resistor as short as possible.
P
P-side IGBTs
N-side IGBTs
SC protection external
Shunt resistor
NU
NV
N1
R
NW
C
CIN
V
NC
Fig.2-2-1 SC protecting circuit
2. SC protection Sequence
SC protection (N-side only with the external shunt resistor and RC filter)
a1. Normal operation: IGBT ON and carrying current.
a2. Short circuit current detection (SC trigger).
It is necessary to set RC time constant so that IGBT shut down within 2.0μs when SC. (1.5~2.0μs is recommended generally.)
a3. All N-side IGBTs' gate are hard interrupted.
a4. All N-side IGBTs turn OFF.
a5. Fo outputs. The pulse width of the Fo signal is set by the external capacitor C
a6. Input = "L". IGBT OFF
a7. Fo finishes output, but IGBTs don't turn on until inputting next ON signal (LH).
IGBT of each phase can return to normal state by inputting ON signal to each phase.
a8. Normal operation: IGBT ON and outputs current.
Lower-side control
input
Protection circuit state
Internal IGBT gate
Output current Ic
Sense voltage of
the shunt resistor
Error output Fo
Publication Date: September 2015
Drive Circuit
U
V
W
Drive Circuit
SC Protection
SC trip current level
a1
Fig.2-2-3 SC protection timing chart
Collector
current
0 2
Fig.2-2-2 Filter time constant setting
a6
SET
a3
a4
a2
SC reference voltage
Delay by RC filtering
a5
11
SC protective level
Input pulse width tw (μs)
.
FO
RESET
a8
a7