IC-SP-06027 R0
Reset
signal
VTR pin
voltage
Over current detected
Delay
Current limit setting
IO
Delay
Power Supply current
IS
Lower arm IGBT operation
ON
OFF
ON
Current limitation
performed
Current limitation reset
IGBT off
Fig. 5-3. Timing chart for current limitation
(b) How to set up
The current limitation setting IO is calculated as follows ;
IO = Vref / Rs
where
Vref: Standard voltage for current limitation
Rs: Shunt resistor
In setting a current limit, you should allow for Vref variance, Rs resistance variance, and the delay
between the time the over current limitation is detected and the time the IGBT is turned off.
This function is not effective for currents that do not flow forward through the shunt resistor, such as
reflux current and power regenerative current (see Figs. 5-4 and 5-5). In practice, users are
requested to observe and check the output currents (the coil currents of the motor) of the IC.
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