33.8 A Decentralized Daisy-Chain-Controlled Switched-Capacitor Driver for Microrobotic Actuators with 10× Power-Reduction Factor and Over 300V Drive Voltage

Abstract

Electrostatic and piezoelectric actuators are used in a number of mm- and cm-scale robotic applications due to their relatively high energy-density at small size and weight [1-3]. Such transducers typically require high drive voltages (100 to 300V) at relatively low frequencies (<; 1kHz) where they present as dominantly capacitive loads (1's to 10's of nF). Challenges associated with the drive circuits for these devices include: 1) a need to generate a high-voltage drive waveform, often boosted from a low-voltage supply; 2) extreme size (<; 1 cm2) and weight (<; <; 1g) constraints; 3) reactive power (CloadVOUT,pp 2fsw) is typically much higher than real power, i.e., mechanical work done by the actuator [4,5]; 4) solutions often require primary (non-rechargeable) batteries which can source but not sink power. Thus, the ideal actuator driver would supply reactive power efficiently, boosting from a low-voltage supply, but also recover this energy during discharge. To work with primary batteries, residual energy must be stored in passive components rather than returned to the supply.