Parallel Motor Control Switching for Load-Deviation Acceleration
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Solution Overview
Problem
Existing electric motor control devices fail to ensure simultaneous high-speed acceleration of multiple electric motors when load deviations occur between them, leading to acceleration failures.
Innovation Solution
An electric motor control device with a power conversion unit, current detection, and a controller that includes a first control unit for d-axis current feedback, a second control unit for speed feedback, and a switching determination unit to switch between these controls based on speed command values and drive information, ensuring load characteristics are accounted for.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single inverter device drives multiple electric motors in parallel, then device complexity is reduced, but acceleration reliability fails when load deviation occurs between motors
Solution Approach 1:
The control device is segmented into multiple independent control units (first control unit 7A, second control unit 7B) that can independently control different motors. This allows the system to handle load deviations between motors while maintaining a relatively simple overall structure by using modular control segments rather than a complex centralized controller.
Solution Approach 2:
The switching determination unit 7-16 dynamically changes control parameters by switching between different control modes (first control and second control) based on real-time motor status. This parameter switching enables the system to adapt to load deviations and maintain acceleration reliability without increasing structural complexity.
2Ease of operation
If synchronous current control is used for multiple motors, then control simplicity is maintained, but acceleration to high speed fails when load deviation occurs
Solution Approach 1:
The control system dynamically switches between synchronous current control (first control) and sensorless vector control (second control) based on real-time motor status. This dynamic adaptation allows the system to maintain simplicity during normal operation while achieving reliable high-speed acceleration when load deviations occur by transitioning to the more robust sensorless vector control mode.
Solution Approach 2:
The system changes control parameters by switching between different control strategies. The switching determination unit monitors motor status and changes the control mode parameter, enabling the system to achieve both control simplicity and reliable high-speed acceleration by selecting the appropriate control parameter based on operating conditions.
3Reliability
If control mode switching is implemented to handle load deviations, then acceleration reliability improves, but control system complexity increases
Solution Approach 1:
The control system is divided into modular segments (first control unit 7A, second control unit 7B, switching determination unit 7-16) that perform specific functions. This segmentation allows the system to implement complex control mode switching while keeping each individual component relatively simple, thereby improving acceleration reliability without excessive overall complexity.
Solution Approach 2:
The switching determination unit 7-16 automatically determines and switches between control modes based on real-time motor status without requiring external intervention. This self-service capability improves acceleration reliability through adaptive control while minimizing the complexity of external control systems by making the switching decision autonomous.
4Reliability
If automatic control switching is implemented, then acceleration failure is prevented, but control complexity increases
Solution Approach 1:
The controller performs automatic control switching through the switching determination unit 7-16 that autonomously monitors motor status and selects appropriate control modes without external intervention. This self-service mechanism prevents acceleration failures by adaptively responding to load deviations while keeping the controller structure relatively simple through automated decision-making rather than complex manual control systems.
Solution Approach 2:
The system implements feedback control where the switching determination unit 7-16 continuously monitors motor status (current, speed, load) and uses this feedback to automatically switch between control modes. This feedback mechanism prevents acceleration failures by detecting and responding to load deviations in real-time while maintaining a simple controller structure through rule-based automatic switching.
Data Source
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AI summary
The invention provides an electric motor control device that drives and controls a plurality of electric motors connected in parallel, the electric motor control device including: a power conversion device configured to convert power from a power supply, and to supply the power to the plurality of electric motors; a current detection device configured to detect an electric current flowing through each of the plurality of electric motors; and a controller configured to control the power conversion device according to a speed command value from an external device and a current value relating to detection from the current detection device, wherein the controller includes a first control unit configured to perform first control on each of the plurality of electric motors based on the electric current, a second control unit configured to perform second control of controlling the plurality of electric motors such that an estimated speed of each of the plurality of electric motors obtained based on the current value follows the speed command value, and a switching determination unit configured to perform switching determination processing of switching between the first control performed by the first control unit and the second control performed by the second control unit according to drive information on at least one or more of the plurality of electric motors.