Current Converter Step-Response Error Voltage Compensation
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Solution Overview
Problem
Existing methods for determining and compensating error voltage in three-phase machines, such as asynchronous machines, are inaccurate due to current-dependent factors like switching delays and voltage drops, which complicate parameter identification and voltage correction.
Innovation Solution
A method that determines error voltage by measuring step responses to desired voltage jumps in a high current range, using the resistance of the load to correct for error voltage influences, allowing for precise compensation and characterization of error voltage behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If error voltage is determined using conventional methods at low currents, then parameter identification is simpler, but measurement precision deteriorates due to error voltage influences
Solution Approach 1:
The patent changes the operating parameter from low current to high current range (at least 30% of nominal current) for resistance determination. This parameter change reduces the relative influence of error voltage on the measurement, thereby improving measurement precision without requiring complex error compensation during the identification process.
Solution Approach 2:
The patent performs resistance determination in advance at high current before normal operation. By establishing the resistance value beforehand under conditions where error voltage is less significant, the system prepares accurate parameters for subsequent error voltage compensation during normal operation, improving overall measurement precision.
2Reliability
If resistance is determined in low current range, then measurement is easier, but error voltage influence increases reducing reliability
Solution Approach 1:
The patent specifies determining resistance in a high current range (at least 30% of nominal current) rather than low current range. This parameter change reduces the relative impact of error voltage on the voltage measurement, thereby improving the reliability of resistance determination despite requiring higher current operation.
3Manufacturing precision
If error voltage compensation is not applied, then control is simpler, but manufacturing precision deteriorates due to voltage deviations
Solution Approach 1:
The patent implements error voltage compensation using the previously determined resistance value. The compensation mechanism uses feedback from the measured current and the stored resistance to calculate and apply the necessary voltage correction, improving output voltage accuracy through a systematic feedback approach.
Solution Approach 2:
The patent determines the resistance value in advance at high current before normal operation begins. This preliminary determination provides accurate parameters for subsequent error voltage compensation during operation, improving manufacturing precision without adding real-time measurement complexity.
Data Source
AI summary
The invention relates to a method for determining an error voltage of a current converter to which a load, in particular in the form of a three-phase machine such as an asynchronous machine, is connected, is determined and if necessary compensated, wherein an output voltage on the current converter is increased stage-by-stage or step-by-step and which is measured here as a current adjusting a step response. The invention further relates to a three-phase machine, for example in the form of an asynchronous machine having power electronics comprising a current converter and in the form of a compensation device for compensating the error voltage of the current converter. The invention further relates to a method for operating and/or controlling such a three-phase machine, in which the error voltage of the current converter is determined and compensated. According to the invention, the error voltage is determined from the current measured as a step response and from a resistance of the load, wherein said resistance is determined from a target voltage jump and from a simultaneously measured actual current jump in a relatively high current range of at least 30% of at least 50% of the rated current of the end stage of the current converter.