Energy savings in concrete production
by O Dobzhanskyi and R Gouws, North-West University
Electricity+Control, August 2014, pages 18 - 23
Enquiries: Tel. 018 299 1902 or email Rupert.Gouws@nwu.ac.za
Download the full article on Energy savings in concrete production in PDF format.
Concrete production technology is a complicated process and electric power is used almost in every stage of the concrete preparation. One of the most energy consuming stages is when the concrete is mixed in concrete mixers. There are many techniques proposed in the literature on how to make concrete mixers more efficient through control applications [1, 2]. Williamson  and Zhao et al  discuss various energy-saving technologies for the concrete mixing process. Most articles are not concerned about electric motors which drive the mixers. Mechanical power of the mixer blades is developed by the electrical drive connected through a gear or directly to the shaft where the blades are attached. Hence, the electric drive efficiency is important for the energy consumption of the concrete plant.
The issue of Permanent Magnet (PM) machines versus induction motors for concrete mixers exists. Some concrete mixer producers  suggest applying PM machines which usually have higher power density, higher efficiency, but also higher cost. Induction machines, however, still dominate in the concrete production process.
This article introduces a novel design of a PM drive for concrete mixers. The high efficiency and simple structure of the proposed motor promises energy savings and lower cost advantages. The motor discussed is not a conventional synchronous PM motor. The machine is designed in such a way that ‘To Degrees of Mechanical Freedom’ (TDMF) of the rotor is achieved by the magnet’s skew on its surface. In other words, the rotor of the machine moves helically (rotary and linear movements are combined). There are various designs of electric machines with TDMF that have been proposed in the literature.
NB: Refer to attached pdf or article in Electricity+Control for list of references.
- Electric power is used in almost every stage of concrete preparation.
- Electric drive efficiency is important for the energy consumption of the concrete plant.
- Whether to use Permanent Magnet (PM) machines or induction motors for concrete mixers is an issue.