Motor Encoder Switching for Precise Current and Speed Control
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Solution Overview
Problem
Existing motor control methods using multiple encoders fail to accurately control current and rotation speed due to inadequate consideration of encoder resolution and detection cycle, leading to detection errors and poor control performance.
Innovation Solution
A power conversion device employing a first encoder with high resolution but slow detection cycle and a second encoder with low resolution but fast detection cycle, along with an encoder switching operation process that dynamically switches between their signals based on rotation speed, using a threshold value with hysteresis to optimize encoder selection and adjust signal ratios for accurate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-resolution encoder is used, then measurement precision is improved, but detection speed deteriorates
Solution Approach 1:
The system dynamically switches between two encoders based on operating conditions. A first encoder with high resolution is used when precise measurement is needed, while a second encoder with fast detection speed is used when rapid detection is required. The encoder switching operation process unit determines which encoder to use based on current operational parameters, making the system adaptable to different speed-precision requirements.
2Productivity
If encoder detection cycle is reduced, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The system adapts its detection cycle based on operational requirements by switching between encoders. When high productivity is needed, the second encoder with faster detection cycle is selected. When measurement precision is prioritized, the first encoder with higher resolution is selected. This dynamic adaptation allows the system to optimize for either productivity or precision depending on the operational context.
3Device complexity
If encoder switching is performed without considering detection phase, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The encoder switching operation process unit incorporates feedback mechanisms to monitor detection phase and determine optimal switching timing. By considering the detection phase in the switching decision, the system maintains measurement precision while performing encoder switching. The feedback ensures that switching occurs at appropriate phases to avoid loss of synchronization or detection accuracy.
Data Source
AI summary
Power conversion device has first position/rotation detector 14, second position/rotation detector 15 whose resolution per rotation of motor is higher than the first position/rotation detector 14 but whose detection cycle is slower than the first position/rotation detector 14 and encoder switching operation process unit 18. The encoder switching operation process unit 18 switches signals between the first and second position/rotation detectors 14, 15 and outputs the signal of the first position/rotation detector 14 or of the second position/rotation detector 15, or adjusts a ratio of the signal between the first and second position/rotation detectors 14, 15 and output a signal obtained by adding adjusted signals. With this, in the power conversion device, the encoder having high resolution and slow detection time and the encoder having low resolution and fast detection time are properly used according to rotation speed, and current and the rotation speed are controlled with high accuracy.