Vacuum Pump Motor Control for Safe Regeneration Mode Transition
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Solution Overview
Problem
Existing vacuum pump systems face instability in transitioning to regeneration mode due to erroneous power restoration detection, leading to potential overvoltage issues during the transition from normal operation to regeneration mode.
Innovation Solution
The system determines whether a power failure is primary or secondary based on the voltage difference between the primary and secondary voltages of the backflow prevention diode, allowing for a controlled transition to the regeneration mode with a sufficient margin to prevent overvoltage, and adjusts the current command value according to the rotational speed of the motor to manage regenerated power effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the system transitions to regeneration mode when the secondary voltage drops to the power-failure detection threshold, then the system can respond quickly to power failures, but voltage overshoot may cause erroneous power-restoration detection and unstable control
Solution Approach 1:
The system performs preliminary classification of power failure type (primary vs. secondary) before transitioning to regeneration mode. By detecting whether the primary voltage has also dropped, the system prepares the appropriate response strategy in advance, preventing erroneous detection and ensuring stable control during the transition.
Solution Approach 2:
The system continuously monitors both primary and secondary voltages of the backflow prevention diode, using feedback from voltage difference detection to determine power failure type. This feedback mechanism allows the system to adjust its transition strategy based on real-time voltage conditions, preventing overshoot-induced errors.
2Reliability
If the system waits for sufficient voltage drop margin before transitioning to regeneration mode, then overvoltage is prevented, but the transition response becomes delayed
Solution Approach 1:
The invention segments power failure detection into two distinct types: primary power failure (both primary and secondary voltages dropped) and secondary power failure (only secondary voltage dropped). This segmentation allows the system to apply different transition strategies - immediate transition for primary failures and delayed transition for secondary failures - optimizing both response speed and safety.
Solution Approach 2:
The system dynamically adjusts the transition timing based on the detected power failure type. For primary power failures, the system transitions immediately to regeneration mode. For secondary power failures, the system waits for sufficient voltage drop margin before transitioning. This dynamic adaptation resolves the contradiction between fast response and overvoltage prevention.
3Device complexity
If the system uses only the secondary voltage for power failure detection, then the detection circuit is simple, but voltage overshoot causes erroneous power restoration detection
Solution Approach 1:
The system merges the detection of primary and secondary voltages into a unified power failure detection mechanism. By combining information from both voltage signals and analyzing their difference, the system achieves accurate power failure type classification without significantly increasing circuit complexity, thereby preventing erroneous detection.
4Productivity
If the system transitions immediately to regeneration mode upon detecting power failure, then productivity is maintained, but overvoltage may adversely affect devices
Solution Approach 1:
The system performs preliminary classification of power failure type before initiating regeneration mode transition. This preliminary action ensures that the system only transitions when safe to do so, preventing overvoltage damage while maintaining productivity by enabling immediate transition for primary power failures where it is safe.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures a safe and stable transition to the regeneration mode by preventing overvoltage occurrences and simplifying control parameters, thereby maintaining system stability during power failures.
Implementation Method 1
the regenerated power of a motor 95 rotates a rotor, which is not illustrated. In the regeneration mode, the regenerated power of the motor 95 is supplied as driving power
Data Source
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AI summary
A vacuum pump and a motor controller that make a safe transition to a regeneration mode while avoiding an overvoltage are provided. A turbo molecular pump includes a power supply unit that converts alternating-current power to direct-current power and outputs the power, the alternating-current power being obtained from an alternating-current power supply, and the motor controller that controls a motor. The motor controller includes: a motor driving circuit that drives the motor when receiving direct-current power or regenerated power; a backflow prevention diode interposed between the power supply unit and the motor driving circuit; a power-failure detection circuit that detects a primary voltage of the backflow prevention diode; a driving-voltage sensing circuit that detects a secondary voltage of the backflow prevention diode; and a motor control circuit that determines, when the primary voltage drops to a predetermined power-failure detection threshold value, whether a power failure is a primary power failure of the alternating-current power or a secondary power failure of the direct-current power based on a voltage difference between the primary voltage and the secondary voltage, and controls the motor driving circuit so as to enter a regeneration mode.