A high voltage converter circuit providing a plurality of power semiconductor devices connected in series, each power semiconductor device is equipped with a monitoring device for monitoring voltage polarity across the power semiconductor device , the monitoring device comprises: - a diode rectifier circuit having a first and a second phase module; - each phase module comprises an AC terminal , DC terminals , two rectifier arms and a sensing resistor ; - each rectifier arm is connected between the AC terminal and one of the DC terminals and comprises at least one diode ; - the sensing resistor of each phase module is connected in series with the diode(s) of the corresponding rectifier arms of each phase module , such that during a positive duty cycle of operation of the circuit a voltage is sensed across the sensing resistor connected to the first phase module and during a negative duty cycle of operation of the circuit a voltage is sensed across the sensing resistor connected to the second phase module ; - a positive voltage monitoring unit for monitoring the voltage sensed across the sensing resistor of the first phase module ; - a negative voltage monitoring unit for monitoring the voltage sensed across the sensing resistor of the second phase module ; - a power supply unit connected with a connection point between the diodes of the rectifier arms of a phase module and the sensing resistor of the phase module; - the DC terminals of the first and the second phase module are electrically connected with each other and have ground potential; - the sensing resistors are connected at one end to one of the rectifier arms and at the other end to one of the DC terminals ; wherein the AC terminals of the phase modules are coupled to the power semiconductor device through a connection interface , wherein the connection interface comprises two clamps . - a diode rectifier circuit having a first and a second phase module; - each phase module comprises an AC terminal , DC terminals , two rectifier arms and a sensing resistor ; - each rectifier arm is connected between the AC terminal and one of the DC terminals and comprises at least one diode ; - the sensing resistor of each phase module is connected in series with the diode(s) of the corresponding rectifier arms of each phase module , such that during a positive duty cycle of operation of the circuit a voltage is sensed across the sensing resistor connected to the first phase module and during a negative duty cycle of operation of the circuit a voltage is sensed across the sensing resistor connected to the second phase module ; - a positive voltage monitoring unit for monitoring the voltage sensed across the sensing resistor of the first phase module ; - a negative voltage monitoring unit for monitoring the voltage sensed across the sensing resistor of the second phase module ; - a power supply unit connected with a connection point between the diodes of the rectifier arms of a phase module and the sensing resistor of the phase module; - the DC terminals of the first and the second phase module are electrically connected with each other and have ground potential; - the sensing resistors are connected at one end to one of the rectifier arms and at the other end to one of the DC terminals ; <EOS>