# Effective Scheme for Inductive Wireless Power Coil Design Using Scan-and-Zoom Optimization
## 3 Proposed Coil Design Method
### Proposed Coil Design Method  
In this section, the proposed coil design method using the scan-and-zoom algorithm is explained. The proposed coil design flowchart is shown in Figure 4 and the detailed design process is shown as follows:  
Figure 3: Scan and zoom algorithm. Step (1) Defining the objective function: At first, the target inductive power transfer and the compensation circuit are decided. For example, a series-series compensation circuit can have higher PTE than other compensation circuits and but another compensation network such as series-parallel, parallel-series, or parallel-parallel can also be considered [16; 17]. When the compensation network is determined, the objective function can be defined as the system performance index. Typically, PTE is the objective function that can be maximized. The PTE formula is usually obtained by solving the circuit equations and is determined by the compensation network [18]. Step (2) Selecting the design parameters and the design constraints: Design parameters can be determined after the coil shape is selected. Design constraints are the parameters that the designer limits for the system design such as the coil radius, air gap, wire diameter, etc. Typically, circular coils can achieve high PTE and high coupling coefficient [19]. In this shape, the outer and inner radii can be designed as parameters and the design constraints are specified by the overall coil size. Step (3) Interfacing MATLAB with ANSYS Maxwell: To calculate the objective function, the coil shape parameter values and the circuit parameter values are exchanged between MATLAB and ANSYS Maxwell, as shown in Figure 5. This process can be automated by interfacing interface MATLAB with ANSYS Maxwell using the script. MATLAB should compute PTE and run the optimization algorithm and ANSYS Maxwell extracts the circuit parameter values such as the inductance, resistance, and coupling coefficient by analyzing the coil in design. To automatically implement this process, the script function of ANSYS Maxwell is internally called MATLAB script. Figure 4: The proposed IPT coil design flowchart. Step (4) Executing the scan-and-zoom algorithm: The scan-and-zoom algorithm is implemented and executed through MATLAB. However, since the circuit parameter values corresponding to each coil shape parameter value are required to calculate the PTE, MATLAB sends the information of the coil shape parameter values during the optimization. The circuit parameter values are then extracted by ANSYS Maxwell and sent back to MATLAB. At this time, the PTE is calculated through the circuit equations, and it is repeatedly executed until the termination condition in Section 3.2 is met. Step (5) Obtaining the PTE and coil shape parameter value results and checking the target PTE. After the algorithm is terminated, the maximum PTE and the corresponding coil shape parameter values are obtained. If the maximum PTE obtained from the algorithm does not reach the target PTE defined in Step 2, the initial coil design constraints are released to satisfy the target \(PTE\). If the target PTE is met, the design is completed and \(Tx\) and \(Rx\) coils are configured with the corresponding coil shape parameter values to build the IPT system. Indeed, the proposed method offers another distinct advantage by utilizing the circuit simulation tool in MATLAB (MATLAB Simulink) as shown in Figure 6. This advantage allows for the consideration of semiconductor losses, which cannot be directly accounted for in the optimization function of ANSYS Maxwell. By incorporating the circuit simulation tool, we can more accurately evaluate the impact of semiconductor losses on the overall system performance, providing a comprehensive analysis that enhances the reliability and effectiveness of the optimization process. This capability further reinforces the superiority of the proposed method in capturing real-world performance aspects that might be overlooked using ANSYS Maxwell alone.