VHDL–AMS modelling and simulation of a planar electrostatic micromotor

Abstract

System level simulation results of a planar electrostatic micromotor, based on analytical models of the static and dynamic torque behaviours, are presented. A planar variable capacitance (VC) electrostatic micromotor designed, fabricated and tested at LAAS (Toulouse) in 1995 is simulated using the high level language VHDL-AMS (VHSIC (very high speed integrated circuits) hardware description language-analog mixed signal). The analytical torque model is obtained by first calculating the overlaps and capacitances between different electrodes based on a conformal mapping transformation. Capacitance values in the order of 10 −16 F and torque values in the order of 10 −11 N m have been calculated in agreement with previous measurements and simulations from this type of motor. A dynamic model has been developed for the motor by calculating the inertia coefficient and estimating the friction-coefficient-based values calculated previously for other similar devices. Starting voltage results obtained from experimental measurement are in good agreement with our proposed simulation model. Simulation results of starting voltage values, step response, switching response and continuous operation of the micromotor, based on the dynamic model of the torque, are also presented. Four VHDL-AMS blocks were created, validated and simulated for power supply, excitation control, micromotor torque creation and micromotor dynamics. These blocks can be considered as the initial phase towards the creation of intellectual property (IP) blocks for microsystems in general and electrostatic micromotors in particular.

Experimental study of a variable-capacitance micromotor with electrostatic suspension

“…The rotation of the rotor is based on the principle of a planar variable capacitance motor [23] and controlled by the rotation electrodes located symmetrically above and below the rotor. Figure 3 depicts the electrode pattern of the top/bottom stators and rotor.…”

Drive and Control of Electromagnetic Drive Module on Reciprocally Rotating Disc Used for Micro-Gyroscope

“…On the other hand, though various patterns of micro-motors have been successively presented, such as electro-static [8,9], electro-magnetic [10] and piezo-electric [11,12], yet the collision between rotation disc and the bearing has not been deeply discussed and successfully prevented. Nevertheless, this issue gradually becomes an attractive topic in the micro-motor research field.…”

Contact dynamics between the rotor and bearing hub in an electrostatic micromotor

“…Many researches, which aim at analyzing [7,15] and simulating [8,[10][11][12] the dynamics of electrostatic micromotor, have been done in recent years. The first experimental prediction of dynamic friction comes from the work on micromotor dynamics by Tai and Muller [4].…”

“…Beerschwinger U et al [5,9] successfully applied finite element analysis (FEA) to simulating variable capacitance (VC) electrostatic micromotor, and calculated out the friction coefficients. Whereby electrostatic force, static and dynamic torques [10][11][12] have been computed by means of FEA simulations. While the motor is in operation, the rotor is intended to be in electrical contact with the ground plane, and the rotor and bearing hub form a pair of contact bodies.…”