0

5

10

15

20

25

15

18

21

24

27

30

Ta = 25˚C

Added resistance=0

Ω

0.5k

Ω

1k

Ω

1.5k

Ω

PC928

Anode

Cathode

C

FS

GND

Application Circuit (IGBT Drive for Inverter)

Operations of Shortcircuit Protector Circuit

Anode

TTL, microcomputer, etc.

Photodiode

Amp.

Constant voltage circuit

Interface

PC928

IGBT protector circuit

GND

C

FS

GND

Feedback to primary side

Cathode

Anode

IGBT

1

2

3

8

9

10

11

12

13

14

Anode

Cathode

TTL, microcomputer, etc.

C

FS

GND

+

CP

IGBT

U

( + )

( - )

Anode

Feedback to primary side

+

V

W

Light emitting diode

Fig. 24 Overcurrent Detecting Voltage

vs. Supply Voltage

Overcurrent Detecting Voltage -

Supply Voltage Characteristics Test Circuit

V

V

FS = OPEN

terminal)

2. Reduction of the IGBT gate voltage, and suppression of the collector current

3. Simultaneous issue of signals to indicate the shortcircuit condition (FS signal) from FS terminal to the microcomputer

4. Judgement and processing by the microcomputer

In the case of instantaneous shortcircuit, run continues.

At fault, input to the photocoupler is cut off, and IGBT is turned OFF.

s

9