Motor Drive Current Gain Switching for Disturbance Stability
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Solution Overview
Problem
Existing gain adjustment methods struggle to maintain stable current control during disturbances, leading to unstable performance due to steep changes in current.
Innovation Solution
A motor drive device with a controller that dynamically adjusts current control gains based on the control state, using a control state judgement unit and a control gain change unit to switch between normal and high-gain settings, employing low-pass filters or integrators to manage gain changes and stabilize current control during disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If high-gain setting is applied to suppress current pulsation, then current pulsation is suppressed, but control responsiveness deteriorates due to increased impact of calculation delay and parameter errors
Solution Approach 1:
The patent applies dynamic gain adjustment by switching between high-gain and normal-gain settings based on the control state. The control state judgment unit determines whether the system is in steady state or transient state, and the gain adjustment means accordingly switches between high-gain setting (for steady state to suppress pulsation) and normal-gain setting (for transient state to maintain responsiveness). This dynamic adaptation resolves the contradiction by making the gain parameter state-dependent rather than fixed.
Solution Approach 2:
The patent changes the control gain parameter based on the control state. By detecting whether the system is in steady state or transient state through the control state judgment unit, the system adjusts the gain parameter accordingly - using high gain during steady state to suppress current pulsation and normal gain during transient state to maintain fast response. This parameter change strategy allows the system to optimize performance for different operating conditions.
2Reliability
If gain setting is switched according to control state, then control responsiveness is improved, but stable current control cannot be performed during disturbance due to steep current changes
Solution Approach 1:
The patent uses feedback through the control state judgment unit that continuously monitors the control state (steady state or transient state) and provides feedback to the gain adjustment means. This feedback mechanism allows the system to detect disturbances through steep current changes and respond by switching to normal-gain setting, preventing unstable control. The feedback loop ensures that gain switching is based on actual system conditions rather than predetermined sequences.
Solution Approach 2:
The patent implements dynamic gain adjustment that adapts to changing system conditions. When a disturbance occurs causing steep current changes, the control state judgment unit detects the transient state and triggers switching to normal-gain setting, which provides stable control during the disturbance. This dynamic adaptation allows the system to maintain stability during transient events while preserving responsiveness during normal operation.
Data Source
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AI summary
Stable current control is performed even at the time of occurrence of disturbance, while the steadily occurring current pulsation is suppressed. A motor drive device 100 includes a power conversion circuit 103 that drives an alternating-current motor 101, and a controller 102 that controls the power conversion circuit 103. The controller 102 includes a voltage command calculation unit 108, a control state judgement unit 112, and a control gain change unit 113. When the determination signal output from the control state judgement unit 112 is switched from a determination signal representing a steady state to a determination signal representing a transient state, the control gain change unit 113 immediately changes the control gain to a value of normal setting, and when the judgement signal output from the control state judgement unit 112 is switched from a determination signal representing the transient state to a judgement signal representing the steady state, the control gain change unit 113 changes, with a predetermined delay time, the control gain to a value of high-gain setting.