System Protection Function - Renesas RA6T2 Application Note

Sensorless vector control for permanent magnetic
synchronous motor - 1shunt current detection

3.1.6 System protection function

This control software has the following error status and executes emergency stop functions in case of
occurrence of respective errors. Table 3-5 shows each software threshold for the system protection function.
Over current error
-
There are two kind of overcurrent protection.
Hardware OCP: When emergency stop signal from the hardware is detected, PWM output ports are
automatically set to high impedance output (without software intervention).
Software OCP: U, V, and W phase currents are monitored in over current monitoring cycle. When an over
current is detected, the CPU executes emergency stop.
Over voltage error
-
The inverter bus voltage is monitored in over voltage monitoring cycle. When an over voltage is detected
(when the voltage exceeds the over voltage limit), the CPU performs emergency stop. Here, the over voltage
limit is set in consideration of the error of resistance value of the detect circuit. When this error occurs, the
CPU performs emergency stop in the side of the motor in which the error occurred.
Low voltage error
-
The inverter bus voltage is monitored in low-voltage monitoring cycle. The CPU performs emergency stop
when low voltage (when voltage falls below the limit) is detected. Here, the low voltage limit is set in
consideration of the error of resistance value of the detect circuit. When this error occurs, the CPU performs
emergency stop in the side of the motor in which the error occurred.
Over speed error
-
The rotation speed is monitored in rotation speed monitoring cycle. The CPU performs emergency stop
when the speed is over the limit. When this error occurs, the CPU performs emergency stop in the side of the
motor in which the error occurred.
Table 3-5 Setting Values of the System Protection Function
Error name Threshold
Over current error Over current limit [A]
Over voltage error Over voltage limit [V]
Low voltage error Low voltage limit [V]
Over speed error Speed limit [rpm]
R01AN6840EJ0100 Rev.1.00
May 23, 2023
For Renesas Flexible Motor Control Series
Monitoring cycle
3.54 Current control
60 Current control
8 Current control
4500 Current control
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