This thesis presents a high-bandwidth multilevel power amplifier based on a flying capacitor topology. This amplifier is designed, in part, to drive a novel tunable magnetic actuator and other electromechanical actuators. These tunable actuators are based on a low-coercive-force AlNiCo magnet, which can be remagnetized in situ to generate a static force output. This is done to minimise heat dissipation. These actuators and others of their type require either high output power, high bandwidth or superior output quality, as is made clear in the literature. To meet these combined requirements, a multilevel power amplifier is proposed. Multilevel converters possess inherent properties, such as high effective output frequencies, lower transistor stresses, and high power density, which overlap with the needs of the power amplifier. The flying capacitor converter is identified as a suitable candidate for use as an amplifier. This converter operates on the principle of series-connected switches, with floating capacitors between the series nodes to generate multiple voltage levels. A simulation is made to further investigate the operating principle of this topology and its suitability for power amplifiers. As there is always a gap between simulation and reality, a hardware prototype is designed and built. The prototype is tested on multiple types of loads, including a hardware prototype of the tunable magnet actuator. The power amplifier prototype functions as expected and is subjected to further tests. During these tests, performance in line with the literature is measured. The overall system efficiency at the nominal operating point is established at 97%, with a worst-case efficiency of 96.2% and a best-case of 98.5%.


Furthermore, a THD of -38 dB, or 0.016%, at the nominal operating point is measured, rivalling theoretical and practical results from the literature. Finally, open-loop bandwidths of 10 kHz are measured, and closed-loop bandwidths of 4 kHz are achieved. While these results are positive, certain limitations of the system are also identified, mainly related to noise and control. Design flaws in the sensing and software are considered the primary culprits. These are not inherent to the core topology used, but are related to the practical challenges when implementing such a high-bandwidth and high-power amplifier.