Analysis of Spherical Core and Laminated Core

Compared with laminated iron cores, the three-dimensional wound iron cores have three significant improvements in structure: the laminations are transformed into windings; the planar arrangement of the core columns is changed to a three-dimensional arrangement; and the cross-sectional shape of the core columns is changed from a stepped shape to a quasi-polygonal shape. This makes the three-dimensional wound Iron Core Transformers have five major advantages over laminated iron core transformers.
1. Material saving and cost reduction
The reason why three-dimensional wound iron core transformers save materials compared to laminated iron core transformers is determined by the unique structure of the three-dimensional wound iron core. The average length of the three magnetic paths of the three-dimensional wound iron core is significantly shorter than that of the laminated iron core. Therefore, the weight of the three-dimensional wound iron core is significantly lighter than that of the laminated iron core, thus saving materials and reducing costs.
Under the same core column cross-sectional area, the same window height size, and the same core column center distance, the weight of the three-dimensional wound iron core is 20% lighter than that of the laminated iron core. Thus, the three-dimensional wound iron core saves 20% of silicon steel sheet compared to the laminated iron core, reducing the cost of iron core materials by 20%. When the silicon steel sheet of the three-dimensional wound iron core is processed into trapezoidal sheet materials, the cutting method of overlapping is used for cutting, so there is no waste during the cutting process and no materials are wasted. In contrast, during the processing of laminated iron core silicon steel sheets, angles need to be punched, and the punched angle waste becomes waste, resulting in about 4% material waste. The cross-sectional shape of the core columns of the three-dimensional wound iron core is a polygon, and the cross-sectional filling coefficient can reach 0.95 to 0.96, while the cross-sectional shape of the core columns of the laminated iron core is stepped, with a cross-sectional filling coefficient of 0.89 to 0.925. Therefore, under the same cross-sectional area, the average winding length of the three-dimensional wound iron core is 2% to 3% shorter, thereby saving copper material by 2% to 3%. 
2. Enhance performance and reduce losses
The reason why the three-dimensional wound core transformer outperforms the Laminated Core Transformer and reduces losses is determined by the structure of the three-dimensional wound core. There are two specific aspects:
(1) Due to the fact that the weight of the three-dimensional wound core is significantly lighter than that of the laminated core, under the same process coefficient and the same unit loss of silicon steel sheets, the no-load loss of the three-dimensional wound core is significantly lower and the performance is better. The relationship can be expressed as: P0=p0·G·K
In the formula:
P0 —— No-load loss; p0 —— Unit loss of silicon steel sheet; G —— Weight of the core; K —— Process coefficient
(2) Due to the fact that the three-dimensional rolled core undergoes annealing treatment during the manufacturing process, the process coefficient is 1.05 to 1.1, while the laminated core generally does not undergo annealing treatment during the manufacturing process, and the process coefficient is 1.2 to 1.4. Under the same silicon steel strip material, the same cross-sectional area of the core column, the same window height dimension, and the same center distance of the core column, the no-load loss of the three-dimensional rolled core transformer is reduced by approximately 30% compared to the laminated core transformer, and the no-load current is reduced by 70% to 80%. 
3. Reducing Noise
The laminated iron core is formed by stacking silicon steel sheets of a certain shape in a specific pattern. The sheets are not closely attached to each other, and during operation, due to the action of electromagnetic force, they vibrate, resulting in high noise. In contrast, the three-dimensional wound iron core is made by winding several trapezoidal strips in sequence. The sheets are more closely attached to each other, and during operation, there is less vibration and lower noise. The noise level of the three-dimensional wound iron core transformer is 7 to 10 dB lower than that of the laminated iron core transformer. 
4. Three-phase balance
Since the three core columns of the laminated iron core transformer are arranged in a planar manner, this causes the magnetic path lengths of the three core columns to be inconsistent. The magnetic path length of the middle core column is shorter, while the magnetic path lengths of the two side columns are more than 20% longer than the average magnetic path length of the middle column. As a result, the no-load currents of the three core columns differ significantly, with the middle column having a smaller no-load current and the no-load currents of the two side columns being larger, leading to three-phase imbalance.
The three core columns of the three-dimensional laminated iron core are arranged in an equilateral triangle, and the magnetic path lengths of the three core columns are exactly the same and short. The no-load currents of the three core columns are equal, thus achieving three-phase balance.