Motor Driving Device Variable Feedback Gain Control
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Solution Overview
Problem
Existing motor driving devices face challenges in maintaining rotational speed feedback control at low speeds, leading to hunting issues due to fluctuations in rotational speed, which are difficult to avoid with existing methods that switch control gain based on external signals rather than internal conditions.
Innovation Solution
A motor driving device with a logic unit, reference clock signal generator, rotational speed signal generator, and rotational speed feedback control unit that adjusts feedback gain in response to the rotational speed signal, utilizing Frequency Locked Loop (FLL) and Phase Locked Loop (PLL) units to stabilize motor speed, along with an integral amplifier that varies gain step-by-step or continuously, and a soft processing unit to suppress frequency fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rotational speed feedback control is performed at low speed, then control precision is improved, but hunting occurs due to rotational speed fluctuation
Solution Approach 1:
The patent applies dynamics by making the feedback gain variable rather than fixed. The feedback gain is dynamically adjusted based on the rotational speed signal, allowing the control system to adapt to different operating conditions. Specifically, the feedback gain is set to a first value when rotational speed is below a threshold and a second value when above the threshold, enabling stable control across varying speeds without hunting.
Solution Approach 2:
The patent changes the parameter of feedback gain based on rotational speed conditions. By monitoring the rotational speed signal and adjusting the feedback gain accordingly (switching between first and second values based on whether speed is below or above a threshold), the system optimizes control precision while preventing hunting at low speeds.
2Adaptability or versatility
If control gain is switched based on external input signals, then adaptability is improved, but the system cannot switch gain based on internal conditions
Solution Approach 1:
The patent uses feedback by continuously monitoring the rotational speed signal (an internal system parameter) and automatically adjusting the feedback gain based on this feedback. The rotational speed feedback control unit receives the rotational speed signal and autonomously switches between different feedback gain values, eliminating the need for external input signals and enabling fully automatic adaptation to internal system conditions.
Solution Approach 2:
The control system performs self-service by automatically adjusting its own control parameters (feedback gain) based on its internal operational state (rotational speed). The system monitors its own performance through the rotational speed signal and autonomously optimizes its control characteristics without external intervention, making the gain switching process independent and self-regulating.
3Stability of the object's composition
If rotational speed feedback control is switched to open control to avoid hunting, then stability is improved, but rotational speed fluctuation occurs
Solution Approach 1:
The patent applies dynamics by implementing a variable feedback gain that adapts to rotational speed conditions. Instead of switching to open control, the system maintains feedback control with a dynamically adjusted gain - using a first feedback gain value at low speeds to prevent hunting and a second feedback gain value at higher speeds for precise control, thereby maintaining both stability and precision across all operating conditions.
Solution Approach 2:
The patent changes the feedback gain parameter based on the rotational speed signal to resolve the contradiction between stability and precision. By switching the feedback gain between first and second values depending on whether the rotational speed is below or above a threshold, the system maintains stable control at low speeds while preserving precision at higher speeds, eliminating the need to switch to open control.
Data Source
AI summary
A motor driving device includes a logic unit configured to control an electrical conduction of a motor, a reference clock signal generating unit configured to generate a reference clock signal based on a rotational speed indication signal, a rotational speed signal generating unit configured to generate a rotational speed signal based on a rotational speed of the motor, and a rotational speed feedback control unit configured to receive the reference clock signal and the rotational speed signal and control the logic unit so that the rotational speed of the motor reaches a target value. The rotational speed feedback control unit changes a feedback gain in response to the rotational speed signal.