Frequency converter

A frequency converter, comprising:

• a DC voltage link, wherein the DC voltage link has a first connection pole at which, during operation of the frequency converter, a positive link potential is present, and a second connection pole at which, during the operation of the frequency converter, a negative link potential is present;
• an inverter, wherein the inverter has a first connection pole at which a positive inverter potential is present during the operation of the frequency converter, and a second connection pole at which a negative inverter potential is present during the operation of the frequency converter;
• a resistive shunt, which is looped-in between the first connection pole of the DC voltage link and the first connection pole of the inverter;
• a differential amplifier, which is designed to generate a test voltage from a potential difference across the resistive shunt, and
• an evaluation unit, which is designed to detect a ground fault on the basis of the test voltage, wherein
• the evaluation unit has a digital input, to which the test voltage is applied,
• the differential amplifier is designed to generate the test voltage, in the absence of a ground fault, at a level which corresponds to a first logic level of the digital input, and
• the differential amplifier is designed to generate the test voltage, in the event of a ground fault, at a level which corresponds to a second logic level of the digital input.

A frequency converter, comprising:

• a DC voltage link, wherein the DC voltage link has a first connection pole at which, during operation of the frequency converter, a positive link potential is present, and a second connection pole at which, during the operation of the frequency converter, a negative link potential is present;
• an inverter, wherein the inverter has a first connection pole at which a positive inverter potential is present during the operation of the frequency converter, and a second connection pole at which a negative inverter potential is present during the operation of the frequency converter;
• a resistive shunt, which is looped-in between the first connection pole of the DC voltage link and the first connection pole of the inverter;
• a differential amplifier, which is designed to generate a test voltage from a potential difference across the resistive shunt, and
• an evaluation unit, which is designed to detect a ground fault on the basis of the test voltage, wherein
• the differential amplifier comprises:
• a first transistor or a diode;
• and
• a second transistor,
• wherein the first transistor or the diode applies a bias to the second transistor such that, in an event of a ground fault, the second transistor alters its circuit state independently, when the potential difference across the resistive shunt is lower than 500 mV.