Patent ID: 8344682
Filing Date: 2013-01-01
Classification: G05B,H02P

Abstract:
1. A method for failsafe monitoring of a movement variable on an electrical drive having a stationary part and a moving part, the method comprising the steps of: generating a first and at least one second drive current as a function of a nominal value of the movement variable, generating an alternating magnetic field in the electrical drive by means of the first and second drive currents, with the alternating magnetic field causing movement of the moving part, determining a first measurement signal, which represents the first drive current, and determining a second measurement signal, which represents the second drive current, by means of a measurement device, determining a field-producing direct-axis current component and a torque-producing quadrature-axis current component as a function of the first and second measurement signals, and determining an actual value of the movement variable as a function of the first and second measurement signals, wherein at least one of the drive currents is generated with a variable test current component which forms a defined test pattern for checking the measurement device, with the test current component being selected such that the defined test pattern appears in the direct-axis current component, while the quadrature-axis current component is substantially free from the test pattern.