Protection Functions And Operating Sequence; Short Circuit Protection - Mitsubishi Electric PSSxxMC1Fx Manual

< Dual-In-Line Package Intelligent Power Module >
DIPIPM+ Series Application note

2.2 Protection functions and operating sequence

DIPIPM+ has two protection functions of short circuit (SC) and under voltage of control supply (UV). And it has
also temperature output function of LVIC (VOT). The operating principle and sequence are described as follows.

2.2.1 Short circuit protection

(1) Outline
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 0.48V typical.
In case of SC protection works, 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.
External parts
Shunt resistor
N1
V
R
C
CIN
Fig.2-2-1 SC protection circuit
(2) SC protection sequence for only low-side with external shunt resistor and RC filter
a1. Normal operation: IGBT ON and outputs current.
a2. Short circuit current detection (SC trigger)
(It is recommended to set RC time constant 1.5~2.0μs so that IGBT shut down within 2.0μs when SC.)
a3. All N-side IGBT's gates are hard interrupted.
a4. All N-side IGBTs turn OFF.
a5. LVIC starts outputting fault signal (fault signal output time is controlled by 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 2016
Drive circuit
P
P-side IGBTs
N-side IGBTs
N
NC
Drive circuit
SC protection circuit
SC trip current level
a1
Fig.2-2-3 SC protection timing chart
U
V
W
0
DIPIPM
Fig.2-2-2 Filtering time constant setting
a6
SET
a3
a4
a2
SC reference voltage
Delay by RC filtering
a5
14
SC protection level
Collector
Current
waveform
2
Input pulse width tw (μs)
)
FO
RESET
a8
a7