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 (6, 7) comprises an AC terminal (8, 9), DC terminals (10, 11), two rectifier arms (12, 13, 14, 15) and a sensing resistor (16, 17); - each rectifier arm (12, 13, 14, 15) is connected between the AC terminal (8, 9) and one of the DC terminals (10, 11) and comprises at least one diode; - the sensing resistor (16, 17) of each phase module (6, 7) is connected in series with the diode(s) of the corresponding rectifier arms (12, 13, 14, 15) of each phase module (6, 7), 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 (10, 11) of the first and the second phase module are electrically connected with each other and have ground potential; - the sensing resistors (16, 17) are connected at one end to one of the rectifier arms (13, 15) and at the other end to one of the DC terminals; wherein the AC terminals (8, 9) of the phase modules (6, 7) are coupled to the power semiconductor device through a connection interface, wherein the connection interface comprises two clamps (23, 24). - a diode rectifier circuit having a first and a second phase module; - each phase module (6, 7) comprises an AC terminal (8, 9), DC terminals (10, 11), two rectifier arms (12, 13, 14, 15) and a sensing resistor (16, 17); - each rectifier arm (12, 13, 14, 15) is connected between the AC terminal (8, 9) and one of the DC terminals (10, 11) and comprises at least one diode; - the sensing resistor (16, 17) of each phase module (6, 7) is connected in series with the diode(s) of the corresponding rectifier arms (12, 13, 14, 15) of each phase module (6, 7), 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 (10, 11) of the first and the second phase module are electrically connected with each other and have ground potential; - the sensing resistors (16, 17) are connected at one end to one of the rectifier arms (13, 15) and at the other end to one of the DC terminals;