System and method for servo control of nonlinear electromagnetic actuators
US6208497A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 26, 1997 |
| Grant date | Mar 27, 2001 |
| Priority date | — |
| Expiry date | Jun 26, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01F7/1607
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
Servo control using ferromagnetic core material and electrical windings is based on monitoring of winding currents and voltages and inference of: magnetic flux, a force indication; and magnetic gap, a position indication. Third order nonlinear servo control is split into nested control loops: a fast nonlinear first-order inner loop causing flux to track a target by varying a voltage output; and a slower almost linear second-order outer loop causing magnetic gap to track a target by controlling the flux target of the inner loop. The inner loop uses efficient switching regulation, preferably based on controlled feedback instabilities, to control voltage output. The outer loop achieves damping and accurate convergence using proportional, time-integral, and time-derivative gain terms. The time-integral feedback may be based on measured and target solenoid drive currents, adjusting the magnetic gap for force balance at the target current. Incorporation of permanent magnet material permits the target current to be zero, achieving levitation with low power, including for a monorail deriving propulsion from the levitation magnets. Linear magnetic approximations lead to the simplest control…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.