Motor Speed Control with Buffered I-Term Limit Reversal Handling
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Solution Overview
Problem
In motor control systems, prolonged deviations between target and actual rotational speeds can lead to excessive integrated value accumulation, causing the operation amount to reach its upper limit, resulting in sharp decreases in motor rotational speed when deviations reverse, hindering desired rotational states, especially under high load conditions.
Innovation Solution
A motor control device with a deviation calculation part and an operation amount calculation part that includes first, second, and third calculation parts to manage the operation amount within predetermined limits, where the second value's upper limit is set larger than the difference between the first value and the operation amount upper limit, preventing sudden decreases in rotational speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an upper limit value is set for the I term value by subtracting the P term value from the operation amount upper limit value, then the integrated value can be prevented from becoming excessively large, but the operation amount responds immediately and tends to decrease sharply when the deviation sharply decreases or reverses, causing the rotational speed to decrease sharply
Solution Approach 1:
The patent applies preliminary action by setting a predetermined upper limit value for the I term that is larger than the difference between the operation amount upper limit value and the P term value. This pre-established larger buffer prevents the operation amount from responding too sharply when deviation reverses, while still preventing excessive integrated value accumulation. The larger predetermined limit acts as a cushion that smooths out sudden changes in the operation amount.
2Stability of the object's composition
If the I term upper limit is set to prevent excessive accumulation, then the control stability is improved, but the responsiveness of the operation amount decreases causing sharp rotational speed drops
Solution Approach 1:
The patent applies parameter changes by modifying the upper limit parameter for the I term from a dynamic calculated value (operation amount upper limit - P term) to a predetermined larger value. This parameter change creates a buffer zone that maintains control stability while preventing the operation amount from decreasing too sharply, thus maintaining both stability and appropriate responsiveness.
Data Source
AI summary
A motor control device includes: a target value acquisition part acquiring a target value of a control parameter of a motor; an operation amount calculation part calculating an operation amount; an output acquisition part acquiring an output of the control parameter; and a deviation calculation part calculating a deviation between the target value and the output. The operation amount calculation part includes: a first calculation part calculating a first value corresponding to the deviation; a second calculation part calculating a second value in a range not exceeding a predetermined upper limit value based on an integrated value of the deviation; and a third calculation part calculating the operation amount in a range not exceeding an operation amount upper limit value based on the first and second values. The predetermined upper limit value is larger than a value obtained by subtracting the first value from the operation amount upper limit value.