Method and processing unit for checking an overvoltage protection circuit for an electric machine, and converter arrangement

A method for checking an overvoltage protection circuit (200) for an electric machine (100),

• wherein the overvoltage protection circuit (200) has a series connection of at least two overvoltage protection units (210, 220),
• wherein a switching unit (215, 225) is connected in parallel to each of the at least two overvoltage protection units (210, 220), so that the particular overvoltage protection unit (210, 220) is bridged by closing the switching unit (215, 225),
• wherein each of the at least two overvoltage protection units (210, 220) includes at least one overvoltage protection component (211, 221, 222),
• wherein each overvoltage protection component (211, 221, 222) limits a voltage, dropping across this component, to a component voltage limit,
• wherein at least one of the at least two overvoltage protection units (210, 220) includes at least two overvoltage protection components (211, 221, 222),
• wherein a voltage tap (230a) is provided between two of the at least two overvoltage protection components (211, 221, 222) of the at least one overvoltage protection unit (220),
• comprising the steps:
• detecting a voltage present at the overvoltage protection circuit (200),
• switching the at least two switching units (215, 225) into at least two different switching configurations and determining a measured value of a voltage present at the voltage tap (230a) in each of the at least two different switching configurations,
• comparing the at least two measured values in each case to an associated comparative value that is determined as a function of the voltage present at the overvoltage protection circuit (200) and the component voltage limits,
• determining the functionality of the overvoltage protection circuit (200) based on at least one comparison result.