Performance of a high-voltage dc amplifier for electrostatic levitation applications

Abstract

High-voltage amplifiers as a means of amplifying the low-output voltage signals of the feedback controllers to the suspension voltages typically in the kilovolts range are often required for electrostatic force generation in electrostatic levitation. This paper proposes a high-voltage do amplifier including an amplitude modulator, a power amplifier, a step-up transformer, a pair of peak detectors, and a voltage feedback channel to stabilize the amplifier outputs in an effort to provide high suspension voltage and fast dynamic response. Since the various carrier frequencies have virtually no effect on the power consumption of the do amplifier by filtering out the high-frequency carrier components with peak detectors while keeping the input signal unaffected, satisfactory dynamic performance can be achieved by choosing a sufficiently high carrier frequency. The operating principle of the dc amplifier is analyzed, followed by an experimental performance evaluation and discussion for electrostatic levitation applications. The experimental results demonstrate the superiority of the high-voltage do amplifier over classical ac amplifiers in terms of dynamic response, force-voltage coefficient, voltage ripple, power consumption, and long-time stability using a carrier frequency of 30 kHz and the closed-loop control scheme.