Linear generator design for concentrating solar power technologies: Optimization and prototype development

Abstract

Abstract An alternative way to generate electricity from solar energy is through the use of generators comprising Stirling engines with a parabolic collector. This study describes a parabolic collector with Stirling engine and investigates the design of a linear mobile generator for these systems. Especially for direct drive in free piston mechanisms proposed for these systems, linear generators are important due to their advantages such as compact structure, light weight, high efficiency and high power intensity. Although conventional one‐phase and three‐phase multi slot/pole models are widely available in the literature, three phase is considered for lower PM cost and to reduce the cost of power electronics and 3/2 slot/pole combination is considered for high speed and frequency. In this study, a new 3/2 slot/pole three‐phase tube‐type linear generator was designed and evaluated for performance and manufacturability. Objective functions were defined for power and efficiency increase to reduce generator power ripple, and the results of Mixed‐Integer Sequential Quadratic Programming, Multi‐Objective Genetic Algorithm (MOGA), and Screening methods were compared and examined. Performance of the two‐dimensional and optimized models was evaluated in terms of induced voltage, power density, efficiency, and output power. The best results were found with MOGA compared to other methods. When compared with the initial value, there was a 97.3% increase in power density for a 32.4% increase in moving weight. Moreover, the efficiency of the MOGA model is improved by 16.2% compared with the initial model. Additionally, significant improvements were shown in terms of thrust coefficient, voltage coefficient, power, and no‐load voltage. A prototype of the model was made and a motor‐driven crank mechanism system was used in place of the Stirling engine to undertake practical measurements.

Keywords

• electric machine analysis computing
• linear machines
• optimization
• solar energy concentrators