Active electric machine control to reduce compressor noise in heat pumps

Thielecke A, Peréz Brovia S, Hübel J, Gänzle D, Herbst J, Becker S (2023)

Publication Type: Journal article

Publication year: 2023


Book Volume: 213

Article Number: 109601

DOI: 10.1016/j.apacoust.2023.109601


As heat pumps help to reduce CO2 emission in residential heating, rapidly growing heat pump sales are predicted. In order to install heat pumps in densely populated residential areas, they must comply with strict noise requirements. Due to advances in control technology in recent years, it seemed promising to investigate the noise reduction potential of a heat pump by means of optimized control. An active control strategy called Current Shaping (CS) has been applied to reduce compressor induced heat pump noise by applying suitable currents to the compressors electric machine. For this purpose, by CS we superimposed suitable current harmonics on the almost constant Iq driving current. In this article we focus on how these modified driving currents affect the noise emitted from the compressor and how this reduces heat pump noise. A compressor test bench was built to perform the CS optimization procedure and to determine noise optimal currents by minimizing compressor vibration. An important finding of this investigation is that the compressor vibrations can be efficiently reduced by CS, and hence also the noise emissions. The vibration reduction potential depends on the compressor harmonic and the operating condition. Additionally, pressure pulsations were measured within the refrigerant pipes and found not to be affected by CS. After the test bench optimization, we applied the optimized currents to a heat pump in a sound chamber to proof that these optimized currents efficiently reduce heat pump noise. For the investigated frequency range of up to 400 Hz our investigations show the three following: First, active electric machine control CS is a suitable method to reduce heat pump noise. Second, the test bench, presented in this paper is suitable to determine the CS current harmonics to reduce heat pump noise. Third, it can be confirmed that the main heat pump noise source is compressor vibration. In general, the two main noise sources of a heat pump are the fan and the compressor. For the compressor there are three noise paths, namely structure-borne and air-borne noise, both excited by compressor vibration, and fluid-borne noise, excited by pressure pulsations in the refrigerant in the piping system. Therefore, from the investigations presented here, it can be derived that the compressor noise is dominating heat pump noise. Moreover, compressor vibrations are dominating heat pump noise and not pressure pulsations in the piping system.

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Thielecke, A., Peréz Brovia, S., Hübel, J., Gänzle, D., Herbst, J., & Becker, S. (2023). Active electric machine control to reduce compressor noise in heat pumps. Applied Acoustics, 213.


Thielecke, Anja, et al. "Active electric machine control to reduce compressor noise in heat pumps." Applied Acoustics 213 (2023).

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