[Objective] With the rapid development of new energy

the weak anti-interference capability of new energy inverters intensifies the risk of cascading grid disconnection after fault disturbances

posing new challenges to current risk prevention and control technologies for protection. This paper investigates the cycle-by-cycle (CBC) current limiting control methods for the fault condition of active neutral point clamped (ANPC) inverters when an AC side short circuit occurs. [Methods] In traditional CBC current limiting control methods

all switching devices of the inverter were turned off when the current exceeded the over-current threshold. However

this frequently triggered current limiting control

resulting in high current change rate di/dt of switching devices

and excessive current flowing through the anti-parallel diode of the insulated gate bipolar transistor (IGBT)

which failed to effectively protect the switching devices in the inverter. Between the control strategy of forcibly turning off all switching devices and the new energy grid disconnection accidents caused by allowing over-current to develop

this paper proposed a technology that controlled the inverter in an intermediate state—partial-switching-off CBC "soft" current limiting control technology. When the control was triggered

the specified switching devices were turned off while the remaining ones were kept on. Finally

a simulation model was established using MATLAB/Simulink to verify the proposed CBC current limiting control method. [Results] The results indicated that this method could effectively reduce the number of triggers

lower the di/dt of the switching devices

and decrease the current peak value of the internal switching devices in the inverter

thereby enhancing the reliability of the inverter. Compared with the full-switching-off CBC current limiting method

the trigger cycles of the partial-switching-off CBC "soft" current limiting were longer

and the trigger frequency was lower. Moreover

the CBC "soft" current limiting method limited the peak current of the switching devices to a lower level

which was beneficial for improving the reliability of the inverter and optimizing the CBC current limiting control method. [Conclusion] The proposed CBC "soft" current limiting control method for ANPC inverters can effectively control inverter current under short-circuit faults

improve the inverter’s short-circuit fault ride-through capability

and provide technical support for the safe operation of new energy grid connection.