Magnetostatic MEMS relays for the miniaturization of brushless DC motor controllers

Abstract

Magnetostatic MEMS relays which are capable of commutating the field windings of a DC brushless motor are presented. The commutation system based on these relays is less than 10% the mass and volume of the electronics it replaces, it eliminates all but two wires from the wiring harness, it requires no external control and it dissipates less than 1/1 OOOth the total motor power. Closure forces greater than 5 millinewton are generated in the relays providing four-wire contact resistance readings of less than 35 milliohms. Utilizing gold-to-gold contacts, hot switching of currents greater than 1 amp has been demonstrated. For lifetimes greater than 10 million cycles (greater than 50 hours of continuous motor operation), switched currents should be limited to less than 120 milliamp. At signal levels of less than 1 milliamp, no failure is seen after greater than half a billion cycles. No contact bounce is seen during make or break. Motor commutation in vacuum down to 5 microtorr and from room temperature down to-30 degrees celsius has been demonstrated.

A MEMS Microreed Switch With One Reed Embedded in the Silicon Substrate

“…There have been several reports on the MEMS magnetic switch, including the latching switch [4], [5], the passive magnetostatic switch [6]- [9], and the microreed switch [10], [11]. Compared to the latching switch and the passive magentostatic switch, the microreed switch has advantages of higher sensitivity and smaller footprint.…”

Μελέτη Και Βελτιστοποίηση Των Ηλεκτρικών Ιδιοτήτων Λεπτών Μονωτικών Υμενίων Που Χρησιμοποιούνται Σε Μικρο-Ηλεκτρο-Μηχανικά Συστήματα (MEMS)

“…Το 1991 ο Larry Larson κατασκεύασε τον πρώτο διακόπτη RF MEMS [3] για μικροκυματικές εφαρμογές και παρά το ότι η διάταξη αυτή παρουσίαζε αρκετά προβλήματα, κίνησε το ενδιαφέρον πολλών ερευνητικών ομάδων. Ακολούθησε η σχεδίαση και κατασκευή διατάξεων RF MEMS με διάφορους μηχανισμούς ενεργοποίησης (ηλεκτροστατικοί [4], μαγνητοστατικοί [5], ηλεκτρομαγνητικοί [6] και ηλεκτροθερμικοί [7]) και με διάφορες τοπολογίες (διατάξεις μοχλών, γέφυρες και μεμβράνες).…”

Design and fabrication of micromachined RF switches and integrated switching circuits

“…The displacement is induced by a microactuator. Various actuation mechanisms then exist, including electrostatic [15][16][17], electrothermal [18], magnetostatic [19] and electromagnetic [20][21][22][23][24] means. Most often, the RF MEMS switch relies on electrostatic actuation, which is based on the attractively electrostatic force exiting between charges of opposite polarity.…”

“…The effect of the beam parameters of w\, wj and w A i on the threshold voltage, V^, is summarized in Table 3-3 The frequency response of the cantilever beam is useful to determine the switching time of the lateral switch and the mechanical bandwidth over which the lateral switch can be used. The frequency response can be determined by d'Alembert's principle as [122] my"+by'+ky = f ex , (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) where (') denotes the derivative with respect to time /, y is the lateral displacement of the cantilever beam relative to the origin of the fixed electrode, m is the effective mass, k and h are the effective stiffness and the damping coefficient of the simplified system, and /^xt(0 is the electrostatic force. The electrostatic force, foJf), between the two electrodes generated by a bias voltage, V, can be simplified as…”

“…(3-21) when y = g 0 . Substitute Eqs (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22), and into Eq (3-21), the dynamic response equation can be obtained as…”