An Insulated Gate Bipolar Transistor, IGBT, switch circuit, comprising: an IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016), comprising an IGBT (T 21) and a first diode (d 21), the first diode (d 21) being connected in parallel with the IGBT (T 21), the anode of the first diode (d 21) being connected to the emitter of the IGBT (T 21) and the cathode of the first diode (d 21) being connected to the collector of the IGBT (T 21), the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) serving as a modulating switch connected to an electric machine and a load thereof; an active clamping protection circuit coupled to the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016), the protection circuit comprising a transient suppression diode and a second diode (d 22), a cathode of the transient suppression diode is coupled to the IGBT (T 21), an anode of the transient suppression diode is connected to an anode of the second diode (d 22); a switch (S 2) also being connected between the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) and the protection circuit, the second diode (d 22) of the protection circuit being connected to the switch (S 2), and a control circuit (C 2), which issues a control signal to control the opening and closing of the switch (S 2), characterized in that, the control signal is a square wave signal of a specific frequency, which controls the switch (S 2) to be in a closed state, when the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) is switched on, so that the protection circuit operates normally, to maintain the closed state for a time period (t 3), when the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) is switched off, to ensure that the protection circuit operates normally in order to effectively suppress a spike value (V TR), and after the time period (t 3), when the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) is still switched off, to be in an open state, so that the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) is not erroneously switched on, wherein the switch (S 2) comprises a PMOS, with a source thereof connected to a cathode of the second diode (d 22) of the protection circuit, and a drain thereof connected to a gate of the IGBT (T 21) of the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016). an IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016), comprising an IGBT (T 21) and a first diode (d 21), the first diode (d 21) being connected in parallel with the IGBT (T 21), the anode of the first diode (d 21) being connected to the emitter of the IGBT (T 21) and the cathode of the first diode (d 21) being connected to the collector of the IGBT (T 21), the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) serving as a modulating switch connected to an electric machine and a load thereof; an active clamping protection circuit coupled to the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016), the protection circuit comprising a transient suppression diode and a second diode (d 22), a cathode of the transient suppression diode is coupled to the IGBT (T 21), an anode of the transient suppression diode is connected to an anode of the second diode (d 22); a switch (S 2) also being connected between the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) and the protection circuit, the second diode (d 22) of the protection circuit being connected to the switch (S 2), and a control circuit (C 2), which issues a control signal to control the opening and closing of the switch (S 2), characterized in that, the control signal is a square wave signal of a specific frequency, which controls the switch (S 2) to be in a closed state, when the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) is switched on, so that the protection circuit operates normally, to maintain the closed state for a time period (t 3), when the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) is switched off, to ensure that the protection circuit operates normally in order to effectively suppress a spike value (V TR), and after the time period (t 3), when the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) is still switched off, to be in an open state, so that the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016) is not erroneously switched on, wherein the switch (S 2) comprises a PMOS, with a source thereof connected to a cathode of the second diode (d 22) of the protection circuit, and a drain thereof connected to a gate of the IGBT (T 21) of the IGBT circuit (2011, 2012, 2013, 2014, 2015, 2016).