Boots – shoes – and leggings
Patent
1992-07-13
1994-02-22
Ruggiero, Joseph
Boots, shoes, and leggings
318811, 364176, G05B 1304, H02P 5408
Patent
active
052893669
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for correction of an actual value of a signal affected by harmonics, the actual value determined by means of a first integrating actual value acquisition device, which value is affected by errors, and the signal is generated from a harmonic-free setting signal by means of a modulation function which approximates a harmonic-free setting signal, and a control system.
In electrical drive technology, analog measurement variables, for example converter current, machine voltage, etc., are frequently converted into digital measurement values using integrating measurement value acquisition devices. With the use of an integrating measurement value acquisition device, measurement noise is filtered out and this measurement device can be structured in a very cost-effective manner. A typical structure of an integrating measurement value acquisition device is explained in greater detail in reference to FIG. 3.
Harmonics of a measurement variable are only filtered out, in this connection, if they have the mean value of zero during the measurement interval (gate time). This is brought about, for example, in space vector modulation, by approximation, in that the gate time is made exactly as large as the duration of a switching state sequence, which approximates a reference vector.
If the harmonics of the measurement variable cannot be ignored during the measurement interval (gate time), the actual value determined by means of the integrating measurement value acquisition device is affected by errors. This error is dependent on the mean value of the harmonics from one gate time to the next. The harmonics that impact the measurement variable, and the amplitude at which they impact it, are dependent on the device which excites these harmonics. In a pulse-width-modulated converter with an intermediate voltage circuit, the converter voltage can be controlled by means of precalculated, optimized pulse patterns. This converter voltage, which is affected by harmonics, is passed to an asynchronous machine. The harmonics are excited by the precalculated, optimized pulse patterns. If the torque is now supposed to be regulated in this asynchronous machine, the converter output current has to be acquired. However, since this is affected by harmonics, the actual value of the torque-producing current becomes incorrect by means of the integrating measurement value acquisition device, causing the torque regulation of the asynchronous machine to become incorrect.
SUMMARY OF THE INVENTION
The present provides a method and apparatus correction of this actual value of a measurement variable affected by harmonics, which value is affected by errors and determined by means of an integrating measurement value acquisition device. This allows an error-free actual value to be made available for further processing.
According to the invention, a harmonic signal is determined from a setting signal affected by harmonics, using the harmonic-free setting signal. The determined harmonic signal is provided to an equivalent model of the control system, and the mean value of the model signal is continuously determined during the gate time intervals of the first integrating actual value acquisition device, by means of a second integrating actual value acquisition device. The actual value affected by errors is corrected by means of the correction value made available at the end of each gate time interval.
Since the error of the actual value that is determined is the result of harmonics whose mean values are not equal to zero, a harmonic signal proportional to these harmonics is first determined. This harmonic signal is converted into a model signal by means of a model of the control system, for example of an inductance, which model signal is proportional to the harmonics of the signal affected by harmonics. Both signals are now passed to an integrating actual value acquisition device in each case, which continuously determines a mean value, within the gate time of the first integrating act
REFERENCES:
patent: 3875491 (1975-04-01), Abraham
patent: 4387421 (1983-06-01), Zach et al.
patent: 4499413 (1985-02-01), Izosimov et al.
patent: 4623830 (1986-11-01), Peneder et al.
Bauer Franz
Braun Michael
Heinle Georg
Schierling Hubert
Ruggiero Joseph
Siemens Aktiengesellschaft
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