Magnetic Levitation Control Device Using Pre-calculated Voltage Sequences
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Solution Overview
Problem
Magnetic levitation systems face challenges in stabilizing the control loops due to delays and the need for balancing fast and slow changes in magnetic forces to maintain stability and stiffness, which is difficult to achieve with existing control methods.
Innovation Solution
A method and device for controlling magnetic levitation systems that select a control direction and voltage values for each control period to decrease position deviation by adjusting the resultant magnetic force, without requiring fast-reacting reference values, allowing for a more stable and stiff magnetic suspension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the outer control loop changes reference values quickly to provide stiff magnetic suspension, then the suspension stiffness is improved, but the inner control loop cannot follow the changes accurately causing instability
Solution Approach 1:
The invention calculates and stores optimal voltage sequences in advance for different position deviation scenarios. When control is needed, the pre-calculated voltage sequence is directly applied without real-time computation delays, allowing the system to respond quickly while maintaining stability. This preliminary preparation resolves the contradiction by enabling fast response without requiring the inner loop to track rapidly changing reference values.
Solution Approach 2:
The control method dynamically selects voltage sequences based on the current position deviation and control direction. The system adapts its control strategy in real-time by choosing from pre-calculated sequences that are optimal for the current state, enabling the outer loop to change reference values quickly while the inner loop follows accurately without instability.
2Stability of the object's composition
If the outer control loop changes reference values slowly to allow inner loop tracking, then control stability is maintained, but the suspension becomes too soft and cannot respond quickly to position deviations
Solution Approach 1:
By pre-calculating optimal voltage sequences for various position deviation scenarios, the system eliminates the need for slow, incremental reference value changes. The pre-computed sequences ensure that when voltages are applied, the inner loop can track accurately from the start, maintaining both stability and rapid response capability.
Solution Approach 2:
The invention replaces the traditional mechanical-like gradual reference value adjustment with a direct voltage application approach. Instead of slowly moving reference values and having currents track them, the system directly applies calculated voltages that produce the desired force changes, substituting the gradual mechanical tracking process with a more direct control mechanism.
3Reliability
If traditional outer and inner control loops are used, then comprehensive control is achieved, but delays are created that limit the speed of magnetic force changes
Solution Approach 1:
The invention extracts the outer loop reference value generation function and integrates it directly into the voltage control process. By removing the separate outer loop that generates reference values, the system eliminates the delay inherent in two-stage control. The voltage sequences are calculated considering both position control and current tracking requirements simultaneously, reducing overall control time while maintaining comprehensive control functionality.
Solution Approach 2:
The invention merges the outer loop position control function with the inner loop voltage control function. Instead of having separate loops operating sequentially, the system combines their functions into a unified control approach where voltage sequences are calculated to simultaneously achieve position correction and ensure accurate current tracking, eliminating the time loss associated with multi-loop delays.
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 enables improved stability and stiffness in magnetic levitation systems by adjusting magnetic forces effectively, reducing deviations and maintaining system stability without the limitations of traditional control loop speeds.
Implementation Method 1
a magnetic levitation system that comprises at least one magnetic actuator (104) comprising at least one winding (105x+, 105x-, 105y+, 105y-) for generating magnetic fluxes (Fx+, Fx-, Fy+, Fy-) for levitating an object (108)
Implementation Method 2
generating magnetic fluxes (Fx+, Fx-, Fy+, Fy-) for levitating an object (108)
Implementation Method 3
controlling voltages (Vx+, Vx-, Vy+, Vy-) directed to the windings (105x+, 105x-, 105y+, 105y-) so as to control magnetic forces (Fx, Fy) directed to the object (108)
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
A control device (101) for controlling a magnetic levitation system comprises a controller (103) for controlling one or more voltages directed to one or more windings of the magnetic levitation system on the basis of a deviation of a position of an object (108) to be levitated from a reference position so as to control a resultant magnetic force directed to the object. The controller selects, for each of temporally successive control periods, a control direction so that ability of the resultant magnetic force to decrease the deviation of the position is improved when the resultant magnetic force is changed in the selected control direction. Thereafter, the one or more voltages are selected in accordance with the selected control direction so as to decrease the deviation of the position by changing the resultant magnetic force. Thus, there is no need for nested control loops which are typically challenging to tune.