Method and apparatus for failsafe monitoring an electromotive drive
First Claim
1. A method for failsafe monitoring of a motor (10) with a three-phase control comprising the steps:
- detecting current and voltage profiles, as provided to a motor (10) by drive electronics (12);
determining a load speed (nL) of the motor (10) using the delected current and voltage profiles; and
failsafe switching off of the motor (10) when the determined load speed (nL) does not correspond to a preset desired speed within a framework of preset tolerances;
wherein determining the load speed (nL) takes place by calculating an observer model with reference to the detected current profile (Imess, Ieff), to the detected voltage profile (Umess, Ueff), to a frequency (fFU, fsync) preset by the three-phase control and characteristic data of the motor (10);
wherein the motor is an asynchronous motor and determining the load speed takes place with reference to the formula;
n =nsyn(1−
s)wherein nsync is the synchronous speed and s is the slip; and
wherein a tilting torque (Mk) and a tilting slip (sk)is calculated from characteristic data of the motor (10) and the load torque (ML) is determined together with the slip (s) and the failsafe switching off takes place on exceeding a limit value.
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Abstract
A method and an apparatus for the failsafe monitoring of an electromotive drive without additional sensors, including a drive having a three-phase control of an electric motor, detection of the current and voltage profiles of each of the three phases, as they are forwarded to the motor by drive electronics, determination of the load speed while using the detected current and voltage values, where the determination of the load speed takes place by calculating an observer model with reference to the detected current, to the detected voltage, to the frequency preset by the control and to the characteristic data of the motor and generation of a failsafe switch signal for the motor when the calculated load speed does not correspond to a preset desired speed within the framework of preset tolerances. The load torque can also be determined and monitored with reference to the observer model.
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Citations
17 Claims
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1. A method for failsafe monitoring of a motor (10) with a three-phase control comprising the steps:
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detecting current and voltage profiles, as provided to a motor (10) by drive electronics (12); determining a load speed (nL) of the motor (10) using the delected current and voltage profiles; and failsafe switching off of the motor (10) when the determined load speed (nL) does not correspond to a preset desired speed within a framework of preset tolerances; wherein determining the load speed (nL) takes place by calculating an observer model with reference to the detected current profile (Imess, Ieff), to the detected voltage profile (Umess, Ueff), to a frequency (fFU, fsync) preset by the three-phase control and characteristic data of the motor (10); wherein the motor is an asynchronous motor and determining the load speed takes place with reference to the formula;
n =nsyn(1−
s)wherein nsync is the synchronous speed and s is the slip; and wherein a tilting torque (Mk) and a tilting slip (sk)is calculated from characteristic data of the motor (10) and the load torque (ML) is determined together with the slip (s) and the failsafe switching off takes place on exceeding a limit value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for the failsafe monitoring of a motor (10) with a three-phase control of an electric motor, the apparatus comprising:
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means (20) for detecting current and voltage profiles of each of the three phases (U, V, W) as provided to the motor (10) by drive electronics (12); means (26) for determining a load speed (nL) of the motor while using the detected current and voltage profiles (Imess), (Umess;
Ieff, Ueff);wherein the determination of the load speed (nL) takes place by calculating an observer model with reference to the detected current profile, to the detected voltage profile, to a frequency (fFU) preset by the three-phase control and to characteristic data of the motor (10); means (28) for generating a failsafe switching signal (30) for the motor (10) when the calculated load speed (nL) does not correspond to a preset desired speed within a framework of preset tolerances; and wherein the apparatus further comprises two redundant microprocessors (22, 24) being provided on which diverse algorithms run. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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Specification