AC Motor Controller Feedforward Frequency Removal
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Solution Overview
Problem
Existing controllers for AC electric motors face instability in speed and position estimation, making it difficult to accurately estimate rotational speed due to external disturbances, and the control system may not return to a stable state even with notch filters.
Innovation Solution
A controller that uses feedforward control with a frequency component remover to stabilize the system by removing predetermined frequency components from the output voltage and estimated rotational speed, reducing unstable control and allowing for stable estimation of rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control with notch filters is used to remove frequency components, then manufacturing precision of speed estimation is improved, but stability of the control system deteriorates when external disturbances occur
Solution Approach 1:
The patent applies preliminary action by using feedforward control to remove frequency components from the output voltage before they can cause instability in the feedback control system. The frequency component remover processes the voltage command value in advance, preventing harmful frequency components from entering the speed estimation process and causing control instability.
Solution Approach 2:
The patent segments the control system into two independent parts: feedforward control for frequency component removal and feedback control for speed estimation. This segmentation allows each part to perform its function optimally without interfering with the stability of the other, resolving the contradiction between precision and stability.
2Measurement precision
If multiple notch filters are added to improve speed estimation accuracy, then measurement precision is improved, but device complexity increases and control stability may be compromised
Solution Approach 1:
The patent replaces the mechanical approach of adding multiple notch filters with a feedforward control mechanism that mathematically removes frequency components. This substitution reduces device complexity by eliminating the need for multiple filter stages while maintaining or improving speed estimation accuracy.
Solution Approach 2:
The patent changes the control approach from passive filtering (notch filters) to active feedforward control with parameter-based frequency component removal. By using voltage command values and current detection values to calculate and remove specific frequency components, the system achieves precise speed estimation without increasing device complexity.
Data Source
AI summary
A controller for an AC electric motor includes an acquirer that acquires at least one of a frequency of an output voltage of a power converter and an estimated value of a rotational speed of the AC electric motor, and a frequency component remover that removes a predetermined frequency component from an acquired value by feedforward control, using the acquired value acquired by the acquirer as an input value.