DIODE NEUTRAL POINT CLAMPED THREE LEVEL INVERTER CURRENT LIMITING CONTROL METHOD AND RELATED CIRCUIT THEREOF

摘要

A diode neutral point clamped three level inverter current limiting control method and a related circuit thereof. The circuit at least comprises: a bridge arm formed by four switching tubes sequentially connected in series and a detection control circuit. The detection control circuit comprises: a first controller (801) a second controller (802) an inverting current collection circuit (803) and an overcurrent occurrence detection circuit (804). The inverting current collection circuit (803) is used for collecting current in a switching tube and providing the collected current to the overcurrent occurrence detection circuit (804); the overcurrent occurrence detection circuit (804) is used for detecting whether the current in switching tube collected by the inverting current collection circuit (803) exceeds a current set value generating a corresponding overcurrent detecting signal and providing the overcurrent detecting signal to the second controller (802); the first controller (801) is used for generating at least two sine pulse width modulation (SPWM) pulse signals with dead zone time; the second controller (802) is used for: when receiving an overcurrent invalid signal indicating that the current in the switching tube is reduced from a value greater than the current set value to a value not greater than the current set value driving one of the switching tubes at the inner side of the bridge arm to be switched on; after a first delay time driving another one of the switching tubes at the inner side to be switched on; after a second delay time controlling one of the switching tubes at the inner side to be switched off and another one of the switching tubes to be normally switched on; and finally controlling all the switching tubes to be switched on or switched off in a normal time sequence. Through the control method and the related circuit the voltage stress of the switching tubes can be reduced so as to ensure that the voltage stress of the switching tubes does not exceed the standard even if the limited current is exceeded.