Method for monitoring a controller of a three-phase electric motor and/or the electric motor

1. A method for monitoring a controller for controlling and/or monitoring a three-winding, three-phase, permanently-excited synchronous electric motor connected in a star configuration in a household appliance, said method comprising the steps of:

measuring two out of three phase currents;

checking whether one of the two measured phase currents is essentially zero;

generating a first error signal when at least one of the two measured phase currents is essentially zero;

checking whether both of the two measured phase currents are essentially not equal to zero;

forming a sum of the two measured phase currents;

generating a second error signal when the formed sum of the two measured phase currents is essentially zero;

incrementing a first count when either the first error signal or the second error signal occurs;

incrementing a second count when the first count repeatedly exceeds a first threshold within a defined period; and

determining a loss of at least one phase current when the second count exceeds a second threshold,

wherein the two measured currents are used to control the synchronous motor with a field oriented vector regulation.

2. The method of claim 1 , further comprising starting a timing operation when the first count exceeds a first threshold within a defined period.

3. The method of claim 2 , wherein the defined period is a specifiable time.

4. The method of claim 1 , wherein the first count is reset when exceeding the first threshold.

5. The method of claim 1 , wherein the second count continues to be incremented as long as the first count exceeds the first threshold within the defined period.

6. The method of claim 1 , wherein the electric motor is used to operate a dishwasher or a washing machine.

7. A household appliance, comprising:

a three-winding, three-phase, permanently-excited synchronous electric motor connected in a star configuration;

a controller for controlling and/or monitoring the motor, wherein the controller is adapted to

measure two out of three phase currents;

check whether one of the two measured phase currents is essentially zero;

generate a first error signal when at least one of the two measured phase currents is essentially zero;

check whether both of the two measured phase currents are essentially not equal to zero;

form a sum of the two measured phase currents;

generate a second error signal when the formed sum of the two measured phase currents is essentially zero;

increment a first count when either the first error signal or the second error signal occurs;

increment a second count when the first count repeatedly exceeds a first threshold within a defined period; and

determine a loss of at least one phase current when the second count exceeds a second threshold,

wherein the two measured currents are used to control the synchronous motor with a field oriented vector regulation.

8. The household appliance of claim 7 , constructed in the form of a dishwasher or a washing machine.

9. A household appliance, comprising:

a three-winding, three-phase, permanently-excited electric motor connected in a star configuration for operating a component of the household appliance;

a current measuring device configured to measure phase currents of at least two of the three phase windings;

a detector circuit which checks whether or not the measured phase currents have non-zero values and;

generates a first error signal if one of the at least two measured phase currents is essentially equal to zero,

generates a second error signal if none of the at least two measured phase currents is essentially equal to zero, but if a sum formed of two measured phase currents is essentially zero,

increments a first count when either the first error signal or the second error signal occurs;

increments a second count when the first count repeatedly exceeds a first threshold within a defined period; and

determines a loss of at least one phase current when the second count exceeds a second threshold,

wherein the two measured currents are used to control the synchronous motor with a field oriented vector regulation.