Method for detecting low impedance condition at output of electrical converter, control unit, computer program product and electrical converter

A method for detecting a low impedance condition at an output of an electrical converter, wherein the method comprising:

• determining a first current value of a first current and a second current value of the first current, and determining a first current difference between the first and the second current values, and
• comparing the first current difference to a first current difference threshold, and if the first current difference is of a predefined magnitude with respect to the first current difference threshold,
• turning off a first voltage driving the first current,
• after said turning off the first voltage,
• determining a decay time of the first current, and
• comparing the decay time to a decay time threshold, and if the decay time is of a predefined magnitude with respect to the decay time threshold,
• detecting the low impedance condition,
• after said comparing the first current difference to the first current difference threshold,
• determining a third current value of the first current at a third time instance, and said determining the decay time comprises determining a time interval during which the first current reduces to a predetermined portion of the third current value.

An electrical converter comprising

• a number of output phases,
• a number of semiconductor switches configured for producing a corresponding number of output phase currents with respect to the number of output phases,
• current determining means for determining the number of output phase currents,
• a control unit for controlling an operation of the electrical converter, and is communicatively connected to said semiconductor switches and said current determining means,
• wherein the control unit is configured to perform a method for detecting a low impedance condition at an output of the electrical converter, the method comprising:
• determining a first current value of a first current and a second current value of the first current, and determining a first current difference between the first and the second current values, and
• comparing the first current difference to a first current difference threshold, and if the first current difference is of a predefined magnitude with respect to the first current difference threshold,
• turning off a first voltage driving the first current,
• after said turning off the first voltage,
• determining a decay time of the first current, and
• comparing the decay time to a decay time threshold, and if the decay time is of a predefined magnitude with respect to the decay time threshold,
• detecting the low impedance condition,
• after said comparing the first current difference to the first current difference threshold,
• determining a third current value of the first current at a third time instance, and said determining the decay time comprises determining a time interval during which the first current reduces to a predetermined portion of the third current value.