High-power and high-efficiency electrostatic actuator

Abstract

The authors have previously developed two types of concatenated electrostatic actuators which are driven by pulse excitation profiles. One of these actuators had excellent performance comparable to that of electromagnetic motors. However, the efficiency of the driving circuit for the actuator was insufficient for practical applications. To improve the efficiency, a new type of electrostatic acluator that can be driven by an ac excitation profile was developed. The new actuator is a linear surface-drive actuator weighing 7g and consisting of a thin slider and a stator. Each element has 3-phase electrodes with the same pitch and 3-phase ac driver connected to the electrodes operate the actuator. A new electrode structure and operation method improve the efficiency by a factor of approximately four. In addition, force and power generation performances are improved. It produces a large power of 1.6W and a propulsive force of 4.4N. The power / weight ratio is improved by a factor of about three, reaching top values of 230Wkg.

Next generation actuators leading breakthroughs

“…Both films are made using flexible printed circuit (FPC) technology. In both of them, three-phase parallel electrodes, which are aligned with regular intervals like 200 µm, are fabricated [18,19].…”

An electrostatic master–slave mechanism with force enhancement by external inductors for cancellation of self- and parasitic capacitances

“…Such an idea was demonstrated by Niino et al in the surface drive type electrostatic film motor named DEMED (dual excitation multi-phase electrostatic drive) [10]. A maximum power-to-weight ratio of 230 W/kg [11] and a thrust force of 310 N [12] was demonstrated with this motor, which shows enough performance to replace electromagnetic motors in macro-scale applications.…”

Evaluation of an Electrostatic Film Motor Driven by Two-Four-Phase AC Voltage and Electrostatic Induction

“…On the other hand, in some industrial or scientific equipments, such as electron beam (EB) lithography system and magnetic resonance imaging (MRI) scanners, nonmagnetic actuators are required that do not interfere with their functions [1] [2]. To fulfill those requirements, various new actuators such as pneumatic actuators, ultrasonic actuators, shape-memory-alloy actuators (SMA), and electrostatic actuators have been studied [3][4][5][6][7][8].…”

“…Electrostatic motors were originally well-known in the field of micro-machines because of its high power density in micro region. However, recent studies have revealed that even centimeter-sized electrostatic actuators can possess high power density by patterning fine electrodes on a large plastic film using the flexible printed circuit (FPC) technology [7][8][9], which are called electrostatic film motors. For example, the film motor called dual excitation multiphase electrostatic drive (DEMED) showed superior output performance (e.g.…”

“…In one type, electric power is supplied to both stator and slider [8], [9]. In the other type, electric power is supplied only to stator [7].…”