Incremental Encoder Motor Control for Direct Rotor Start-Up
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Solution Overview
Problem
Existing methods for controlling electric motors with incremental encoders face challenges such as complex calibration processes, labor-intensive manual operations, and increased costs due to additional sensors or structures, which are not suitable for applications where mechanical structures cannot be freely rotated or moved upon power-on.
Innovation Solution
A controller with a quadruple frequency circuit, driver circuit, and non-volatile memory, coupled with a multi-phase control circuit, performs automatic calibration and direct start-up phases to achieve near-absolute-encoder accuracy without additional sensors, allowing the electric motor to start directly and accurately without rotor position initialization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors or structures are added to the incremental encoder to determine rotor position, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent performs preliminary action by conducting automatic calibration during the production phase to store offset counter values in non-volatile memory before the product is delivered to the user. This preliminary calibration eliminates the need for manual operations and enables direct start-up without rotation during normal use, resolving the contradiction by achieving high measurement precision through advance preparation rather than adding complex sensors.
Solution Approach 2:
The patent creates a copy of the absolute position information by storing the offset counter value (which represents the relationship between the rotor's 0 degree and the encoder's index angle) in non-volatile memory. This copied information allows the system to reconstruct the absolute position reference during direct start-up without requiring additional absolute encoders or complex sensing structures, thus achieving high measurement precision with simple hardware.
2Manufacturing precision
If manual calibration operations are performed to calibrate the difference between rotor 0 degree and encoder index angle, then manufacturing precision is improved, but ease of operation deteriorates due to complicated procedures
Solution Approach 1:
The patent implements self-service by designing an automatic calibration function that autonomously determines the offset counter value between the rotor's 0 degree and the encoder's index angle during production, without requiring manual intervention. The system automatically stores this calibration data in non-volatile memory, enabling direct start-up operations without manual calibration procedures, thus achieving high manufacturing precision while dramatically improving ease of operation.
Solution Approach 2:
The patent performs preliminary action by completing the calibration process during the production phase and storing the offset counter value in non-volatile memory before the product reaches the user. This preliminary calibration eliminates the need for complex manual operations during normal use, allowing the motor to start directly without rotation, thereby resolving the contradiction between manufacturing precision and ease of operation.
3Measurement precision
If the rotor is controlled to rotate to the index angle before normal operations, then measurement precision is improved, but productivity deteriorates due to additional initialization time
Solution Approach 1:
The patent performs preliminary action by storing the offset counter value (which contains the positional relationship between rotor 0 degree and encoder index angle) in non-volatile memory during production. This preliminary preparation enables the system to directly calculate the initial position during start-up without requiring the rotor to physically rotate to the index angle, thus achieving high measurement precision while eliminating the time-consuming rotation initialization process and improving productivity.
Solution Approach 2:
The patent creates a copy of the position reference information by storing the offset counter value in non-volatile memory. This copied information allows the system to directly determine the initial position during direct start-up without requiring the rotor to physically rotate to the index angle, thereby achieving high measurement precision while significantly improving start-up speed and productivity.
4Measurement precision
If additional circuits or structures are added to achieve absolute position functionality, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent creates a copy of the absolute position reference information by storing the offset counter value in non-volatile memory. This copied data allows the system to reconstruct the absolute position reference during direct start-up without requiring additional absolute encoders or complex absolute position generating circuits, thus achieving high measurement precision while keeping the control circuit simple and cost-effective.
Solution Approach 2:
The patent changes the operational parameters by introducing a multi-phase control mode that includes automatic calibration phase and direct start-up phase. By changing the control strategy rather than adding hardware, the system achieves high measurement precision through software-based offset compensation, avoiding the need for additional circuits or structures and keeping the device complexity low.
Data Source
AI summary
A controller for controlling an electric motor module equipped with incremental encoder and operation method thereof are provided. The controller includes a quadruple frequency circuit, a driver circuit, a non-volatile memory (NVM) and a multi-phase control circuit. The multi-phase control circuit can perform multi-phase control with aid of the NVM, for example: reading an offset counter value from the NVM; executing an initial angle estimation procedure, generating an initial counter value according to an estimated initial angle and the offset counter value, and starting utilizing the driver circuit to directly control the electric motor to start with the estimated initial angle and utilizing a counter to perform counting operations; calculating a counter value error and clear the current counter value to be zero; and performing compensation corresponding to a predetermined compensation times count according to the counter value error, respectively, to control the rotor to reach a target angle.