The most important sources are some IEEE Transactions. In addition, some people are publishing about this topic in

1) Electric Power Systems Research (Elsevier, Impact Factor: 2.688, CiteScore: 3.32)

2) International Journal of Power Electronics and Drive Systems (IJPEDS) (CiteScore: 1.08)

3) IET Power Electronics (Impact Factor: 3.547, CiteScore: 4.310)

4) International Journal of Circuit Theory and Applications (Wiley,  Impact Factor: 1.571)

5) Journal on Wireless Communications and Networking (Springer, Impact Factor: 1.529)

6) International Journal of Wireless Information Networks (Springer, SNIP: 1.231)

Dear Adrian,

I'm so thankful for the proposed journals

Regards

In addition to Adrian's helpful suggestions, you can find some papers on WPT in the following journals:

1- Sensors and Actuators: A Physical (IF:2.5, CiteScore: 2.79)

2- Sensors Journal (MDPI) (IF: 2.677)

3- IET microwave, antenna, propagation (IET-MAP)

Regards

There are some relevant works in journal of circuit theory and application (Wiley)

Thank You, Mr  Iman for your suggestions 

1. Energies (MDPI).

2. Microwave and optical technology letters (Wiley).

3. Radio engineering.

4. Progress in electromagnetics.

5. Sensors and Actuators A (Elsevier).

I have read some really good WPT papers on

1. Cambridge wireless power transfer journal. (no impact factor yet, was launched in 2014, I think)

2. Applied Physics letters

3. AIP Advances