THE INFLUENCES OF T-JOINT CORE DESIGN ON NO-LOAD LOSSES IN

TRANSFORMERS

Guide : Sruthi Nath.S Gokul P K

Asst. Professor PIAKEEEO14

Dept. of EEE

INTRODUCTION

Transformer Efficiency can be as high as 99%.

Depends on the design of the joints between the limbs and the yokes.

Performance is compared based on T-Joint configurations of 23°, 45°, 60°, and 90°.

Flux distribution and loss calculation are analyzed using Finite Element Method.

Designed and Simulated Using Quick Field Software

To find the best core design based on T-Joint configuration in terms of No-Load losses and Flux distribution.

A LOOK AT LOSSES Two types of transformer losses,

1. Load losses.

2. No-load losses .

NO Load losses depends on1. Type of Joints.

2. Air gaps.

3. Overlap area at the Joints.

4. Accuracy of dimensions (angles at the corner joints).

5. Flatness of the laminations.

6. Grade of the material used.

No load losses do not vary , will be constant over the life time.

Forms less than 1% of the Power Rating.

Represents sizable operating expense, when energy costs are high.

Can be reduced by understanding localized flux and loss distributions in the Transformer core.

Alternatively Load losses arise from the resistive components of the windings.

TRANSFORMER CORE LOSSES

Efficiency depends on the type of corner joint between Yokes and limbs.

Two types of joints,1. Mitred Joints

2. Non-Mitred Joints

Non-Mitred Joints are used in small rating Transformers.

Here we are considering Mitred joints.

Flux crosses from limb to the yoke along Grain orientation.

Rolling direction of the strip is in the easy direction of magnetization.

Flux deviates from rolling direction at the corners.

Power losses will increase, as well as the Magneto static and the noise output of the core.

Selection of core material affects the performance of Transformers.

TRANSFORMER MODELING

Accurate characterization of the Electromagnetic behavior is done by Finite Element Method.

Concept of dividing original problem’s domain in to a group of sub-domains.

Applying Numerical formulation based on Interpolation theory to the elements.

Quick Field can perform both linear and non-linear Magneto static analysis.

Modeling of the core design and calculation of No- load losses.

CALCULATIONS

No-load loss = Energy density * f * volume surface.

Efficiency = Output power/Input power

THE SIMULATION OF TRANSFORMER DESIGN

After simulation , we will obtain the output data such as flux density, flux flow, energy density, permeability etc.

Now we can determine winding Inductance and Transformer losses.

General problem parameters are stored as in the problem.

DEVELOPMENT

Three stages

1. Geometry description and Manipulation.

2. Definition of properties , Field sources, and boundary conditions.

3. Mesh Generation

RESULT AND DISCUSSION

Results were analyzed according to different core configurations.

Graphical Representation of Transformer behavior such as direction of flux, flux density, permeability, energy density

Four packets consisting of four different angles of T-joint were analyzed.

FLUX DISTRIBUTION

Flux density in the centre limb is maximum.

Due to collection of both left and right flux directions

Highest flux density was recorded with a 90° T-Joint.

Energy will be stored in regions such as air gaps, insulation between conductors, and spaces within the conductors.

Highest Energy density was with a 90° T-joint.

23° and 60° of the T-joint was recorded the highest values of permeability.

Loss calculation are achieved using these data

Highest loss was recorded with a 90° and lowest loss was recorded with a 60° T-Joint.

CONCLUSION

Flux distribution and transformer losses have been investigated for the overall packages.

Observed that 60° T-Joint is the optimal configuration.

Losses increase by internal compressive stresses through out the yokes and limbs.

A higher energy density will increase the transformer losses.

Core losses can be minimized by controlling the flux distribution.

Adjusting the shape and angle of the core reduces noise due to the electromagnetic forces.

Small size Transformers with high capacity and performance should be designed in future.

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