Magnetic Bearing Vacuum Pump Control With Switchable Rigidity Modes
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Solution Overview
Problem
Conventional vacuum pump controllers face challenges in achieving accurate and stable control during steady operations, are susceptible to disturbances, and require larger size and higher power consumption due to multiple power supplies and amplifier circuits, which also lead to increased braking time when omitting the regenerative resistor.
Innovation Solution
A vacuum pump system with a rotating body supported by an electromagnet, equipped with a position sensor and an excitation control circuit that employs two excitation control modes, adjusts the output signals based on a ratio to reduce size and power consumption, and omits the regenerative resistor by using a single direct-current power supply, allowing for quick disturbance suppression and stable control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple power supplies and amplifier circuits are used for high-speed position control during resonance passage, then control accuracy and disturbance resistance are improved, but device size and power consumption increase
Solution Approach 1:
The patent merges multiple power supplies into a single power supply unit. The controller integrates both high-voltage and low-voltage amplifier circuits within one device, combining functions that were previously separated into multiple independent units. This integration maintains the dual-voltage capability while reducing overall device size and component count.
2Reliability
If multiple power supplies and amplifier circuits are used for high-speed position control during resonance passage, then disturbance resistance is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic switching between high-voltage and low-voltage modes based on operational requirements. The controller automatically selects high-voltage mode during resonance passage or disturbance conditions to maintain strong control force, and switches to low-voltage mode during normal operation to reduce power consumption. This dynamic adaptation optimizes the balance between disturbance resistance and energy efficiency.
3Device complexity
If regenerative resistor is omitted to reduce size, then device size is reduced, but braking time increases
Solution Approach 1:
The patent replaces the regenerative resistor with an electromagnetic braking system. The electromagnet, already present for magnetic levitation control, is utilized to generate braking force by creating magnetic drag on the rotating body. This substitution eliminates the need for a separate regenerative resistor while achieving effective braking, thus maintaining compact device size.
4Speed
If high voltage is used to quickly increase current through electromagnetic windings, then response speed is improved, but power consumption increases
Solution Approach 1:
The patent employs periodic switching between high-voltage and low-voltage power supplies based on control requirements. High voltage is applied only during transient conditions requiring rapid response (such as resonance passage or sudden disturbances), while low voltage is used during steady-state operation. This periodic action pattern maintains fast response capability when needed while minimizing overall power consumption.
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
The solution enables accurate and stable control, reduces size and power consumption, and shortens the pump stop time by using a single amplifying means and adjusting the signal ratios dynamically, thus improving operational efficiency and reducing heat generation.
Implementation Method 1
a rotating body supported and floated in the air by an electromagnet
Implementation Method 2
a position sensor that detects the radial or axial position of the rotating body
Implementation Method 3
an excitation control circuit that controls excitation of the electromagnet so as to set the rotating body at a predetermined position
Data Source
AI summary
A position deviation calculated by a subtractor of a vacuum pump is input to the PIDs of three modes. The first PID is a PID controller for a high-bias mode, the second PID is a PID controller for a high-rigidity mode, and the third PID is a PID controller for a low-rigidity mode. The output signal of the third PID is extracted as a change of an indicator current for each clock of a PWM frequency and then the mean value of a change of an indicator current for several clocks is determined in a calculating unit. At this point, a switching control unit performs an operation on whether the mean value of the averaged change of the indicator current is larger than a preset redetermined value and then according to the result, an α value is outputted in the range of 0 to 1 from the switching control unit.