An Ultracompact Dual-Stage Converter for Driving Electrostatic Actuators in Mobile Microrobots

Electrostatic actuators are being widely investigated to convert electrical energy into mechanical deformation in a broad variety of microrobotic applications. Both electrostatic gap closing and comb drive actuators require high excitation voltages for high performance operation. In the majority of applications, external bulky and heavy power supplies are used to provide such high voltages, which inevitably bring limitations on autonomous operation. One of the major challenges toward enabling operation of these systems without a bulky external power source is the development of ultralight and high power density power electronic interfaces (PEIs) with large step-up gains. In this paper, a special circuit topology, controlled by a pulse frequency modulation scheme, is introduced to meet stringent electrical and drive voltage requirements of electrostatic actuators. An ultracompact 63 mg (excluding PCB mass), 31.5 mm ², and 500 mW PEI has been designed and fabricated. Experimental validations have been carried out to verify the circuit´s ability to drive an 110-V-input electrostatic inchworm motor at 1-kHz actuating frequency.