Control device for a bridge circuit for controlled AC current generation, the bridge circuit having at least one bridge branch (9, 10, 11) that has at least one high-side field-effect transistor, FET (12, 14, 16), at least one low-side FET (13, 15, 17), and an AC output (23, 24, 25) therebetween, wherein the control device has - a voltmeter (2, 3) for each FET of a bridge branch, wherein each voltmeter, in order to measure the drain-source voltage, is able to be connected to the respective FET and outputs measured values and/or state values; - a field-effect transistor in the form of a phase isolator (5, 6, 7) for each AC output, wherein the phase isolator/isolators is/are able to be connected to a respective AC output and is/are able to be switched by a respective control signal; and - a logic circuit for detecting the values of the voltmeters and for outputting control signals to a respective phase isolator, wherein the logic circuit outputs the control signals for turning off the corresponding phase isolator/isolators on the basis of the detected values, characterized in that the voltmeters are designed to determine and to output a first and a second state: - the first state is present if the measured voltage is below a predetermined value, in particular below -0.5 volts, and serves to determine the current direction; and - the second state is present if the measured voltage is above the predetermined value, in particular above -0.5 volts, and serves to determine that either no current is flowing through the body diode of the FET, or the FET has a drain-source short circuit and is damaged. - a voltmeter (2, 3) for each FET of a bridge branch, wherein each voltmeter, in order to measure the drain-source voltage, is able to be connected to the respective FET and outputs measured values and/or state values; - a field-effect transistor in the form of a phase isolator (5, 6, 7) for each AC output, wherein the phase isolator/isolators is/are able to be connected to a respective AC output and is/are able to be switched by a respective control signal; and - a logic circuit for detecting the values of the voltmeters and for outputting control signals to a respective phase isolator, wherein the logic circuit outputs the control signals for turning off the corresponding phase isolator/isolators on the basis of the detected values, characterized in that the voltmeters are designed to determine and to output a first and a second state: - the first state is present if the measured voltage is below a predetermined value, in particular below -0.5 volts, and serves to determine the current direction; and - the second state is present if the measured voltage is above the predetermined value, in particular above -0.5 volts, and serves to determine that either no current is flowing through the body diode of the FET, or the FET has a drain-source short circuit and is damaged. - the first state is present if the measured voltage is below a predetermined value, in particular below -0.5 volts, and serves to determine the current direction; and - the second state is present if the measured voltage is above the predetermined value, in particular above -0.5 volts, and serves to determine that either no current is flowing through the body diode of the FET, or the FET has a drain-source short circuit and is damaged.