Method for starting and operating a bldc motor and bldc motor

A method for starting and operating a brushless direct current motor having a rotor with exciter magnets, a stator with at least three stator coils, and a control and evaluation unit, wherein one phase current is always able to be applied to each of the at least three stator coils, and a rotating stator magnetic field is generated by the stator coils, the method comprising:

• a) carrying out an initialization phase having a defined start time, a defined initial starting field angle of the stator magnetic field and a defined angle rising rate;
• b) carrying out a partial cycle, including:
• b1) carrying out a rising phase by increasing a current field angle with a change in voltage application to the stator coils until a final field angle is reached which exceeds a starting field angle by 60°, wherein the starting field angle corresponds to the initial starting field angle when the rising phase is carried out for the first rime and to a final field angle of a previous rising phase when carried out repeatedly;
• b2) carrying out an analysis phase by keeping the current field angle due to the voltage application to the stator coils being kept constant, continuously recording a difference in current between two phase currents of a same direction of flow, the control and evaluation unit analyzing the recorded difference in current for the presence of a current eye, wherein the current eye is formed between a time of a first occurrence of a current difference of 0 between the two phase currents of the same direction of flow and a time of a second occurrence of a current difference of 0 between the two phase currents of the same direction of flow, where immediate commutation takes place when a current eye is detected or where without detection of a current eye, commutation takes place after a pre-definable time interval has elapsed, terminating the analysis phase after commutation has been carried out;
• c) repeatedly carrying out the partial cycle until the final field angle has increased to a value of 360°, the partial cycles together defining a total cycle;
• d) repeatedly carrying out the total cycle.

A brushless direct current motor, comprising:

• a rotor having exciter magnets;
• a stator having three stator coils configured for always having one phase current applied to each of the three stator coils and said stator coils configured for generating a rotating stator magnetic field;
• a control and evaluation unit, said control and evaluation unit and said three stator coils configured for carrying out initialization phase having a defined start time, a defined initial starting field angle of the stator magnetic field, and a defined angle rising rate,
• said control and evaluation unit configured for carrying out a partial cycle having a rising phase and an analysis phase;
• the rising phase being carried out by increasing a current field angle with a change in voltage application to said stator coils until a final field angle is reached which exceeds a starting field angle by 60°, the starting field angle corresponding to the initial starting field angle when the rising phase is carried out for the first rime and to a final field angle of a previous rising phase when carried out repeatedly;
• the analysis phase being carried out by keeping the current field angle due to the voltage application to said stator coils being kept constant, continuously recording a difference in current between two phase currents of a same direction of flow, the control and evaluation unit analyzing the recorded difference in current for the presence of a current eye, wherein the current eye is formed between a time of a first occurrence of a current difference of 0 between the two phase currents of the same direction of flow and a time of a second occurrence of a current difference of 0 between the two phase currents of the same direction of flow, where immediate commutation takes place when a current eye is detected or where without detection of a current eye, commutation takes place after a pre-definable time interval has elapsed, terminating the analysis phase after commutation has been carried out;
• wherein the partial cycle is repeated until the final field angle has increased to a value of 360° and a total cycle is achieved when the final field angle increases to 360°;
• wherein the total cycle is configure to be carried out repeatedly.