PhD Thesis Proposal: Yanqiao Li

For Zoom link, contact yanqiao.li.th@dartmouth.edu.

"Pseudo-resonant switched-capacitor drive circuits for electrostatic loads"

Abstract

In recent years, piezoelectric and other electrostatic actuators have gained traction in a variety of small-scale electromechanical applications including mm- and cm-scale robotics and human-tactile feedback (haptics) due to improved force-displacement, more flexible geometries, and smaller size compared to conventional electro-magnetic actuators. However, electrostatic actuators (including piezoelectric devices) typically require high-voltage drive signals to achieve maximum benefit; the use of these devices in small electromechanical systems further motivates stringent size and weight constraints of the drive circuitry. Example system constraints in 'micro' robotic applications include a need for drive voltages of hundred volts to several kilovolts, volume << 1 cm³, and weight <<1g.

This proposal explores new topologies and integration strategies for the drive circuitry for small-scale, high-voltage electrostatic actuators. Specifically the proposal outlines a reconfigurable series-parallel switched-capacitor (SC) DC-DC converter that can both provide the needed voltage conversion (boost) from a low-voltage supply or battery and control the actuator drive voltage waveform. Importantly, the proposed system is both efficient and small size. The SC driver can be modelled as a pseudo-resonant system which can both provide and recover the reactive (CV²) power which dominates power flow in typical electrostatic loads. The proposal will provide an overview of past work in electrostatic drive systems, including hard-switching drivers and strategies which use predominantly magnetic-boost topologies. An overview of the switched-capacitor approach will be provided in order to outline advantages of the pseudo-resonant SC converter. Implementation details of several integrated-circuit (IC) prototypes will be presented including the need for scalable high-voltage level shifters, local voltage references, and embedded control. Future work which extends the concept to other applications, specifically gate drivers for modern power semiconductor devices will be discussed.

Thesis Committee

• Prof. Jason T. Stauth (Chair)
• Prof. Charles R. Sullivan
• Prof. John X.J. Zhang

Contact

For more information, contact Theresa Fuller at theresa.d.fuller@dartmouth.edu.