Design and control of adaptive vibration absorbers mounted on an air conditioning compressor

Previous research works investigated the application of adaptive vibration absorbers (neutralizers) to an airconditioning unit to reduce the vibration due to the disturbance force of rotational systems with fixed excitation frequency. The work presented in this paper now takes the next step by applying the adaptive vibration neutralizers to a compressor with variable rotational speed driven by a frequency converter. In order to have the ability to cover a broad scope of application, the vibration neutralizers are developed from modular components to ensure scaling possibility. The vibration neutralizers are built from masses attached to the ends of two cantilever beams, acting as springs, with attached piezoelectric patch transducers. Corresponding to the rotational speed of the air conditioning compressor, three vibration neutralizers with resonance frequency of 24.2 Hz are manufactured. The resonance frequency can be tuned dynamically by emulate either "virtual" dynam ic mass or "virtual" dynamic stiffness respectively. The "virtual" dynamic stiffness will be implemented in this paper by feeding back the strain of the beam with corresponding gain factor to achieve the needed resonance frequency. The control method is implemented separately in each mounting point of the adaptive vibration neutralizers at the compressor. The gain for tuning the virtual mass is adapted in real-time due to the difference in phase between the acceleration of the masses and the mounting. The effects of the adaptation of the vibration neutralizers compared to the passive vibration neutralizers are shown by the reduction of the acceleration of the compressor mounting plate at the disturbance frequency.