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Wireless Power Transfer Topologies for Electric Vehicle Battery Charging

Wireless Power Transfer Topologies for Electric Vehicle Battery Charging

Electric vehicles are gaining an edge over the internal combustion engine vehicles used in the transportation sector. These vehicles are environment-friendly and contribute towards the global sustainability concern. As the vehicles run on battery, wireless charging of EV batteries is introduced to replace the traditional wired methods of charging. 

In this blog, we’re going to discuss the two techniques, Static & Dynamic Wireless Power Transfer Topologies, for EV battery charging. 

Classification of Wireless Power Transfer Techniques

Wired EV Battery charging systems create a lot of problems during extreme climatic conditions such as rainfall and snowfall. Hence, the WPT system is used for EV battery charging to eliminate the drawbacks of wired systems. The WPT techniques are of two types: 

  1. Static EV Battery Charging
  2. Dynamic EV Battery Charging

Static Wireless EV Battery Charging Technique

In this technique, inductive and capacitive methods are utilised for transferring power. EV is charged when it is in parking or static condition. One side of the coupled coil is placed in the charging point, while the other side is placed at the bottom of the vehicle for wireless power transfer. Now, let’s have a look at the different static EV battery charging techniques.  

1. Microwave Power Transfer 

The MPT method consists of a rectifier, high power microwave generator, rectenna, DC-DC Converter, EV battery, and a utility grid. The voltage of the utility grid which is operating at a frequency of 50 Hz is converted into DC voltage using a rectifier. This DC voltage is sent to microwave signal generators to convert it into microwave radio waves and then sent to the rectenna. Rectenna converts it again into DC voltage to transfer it to the DC-DC converter for converting the output in the required levels of DC voltage to charge the EV battery efficiently.

2. Inductive Power Transfer 

In this technique, two magnetically coupled inductors are used in a single magnetic field without having any physical contact between them. Then, AC voltage with high-frequency is sent from one side to the other side of the coupled inductor. Here, the utility grid AC Voltage is converted into DC voltage using a rectifier. This DC Voltage is converted into AC Voltage of high-frequency for wireless power transfer. 

3. Inductively Coupled Power Transfer 

The ICPT technique was invented to increase the efficiency of the IPT charging system. Under this, extra capacitors are connected to the two coils of the coupled inductor for compensating leakage in its magnetic field and boosting the efficiency of the system.  

4. Capacitive Power Transfer 

The IPT technique also produces interference in the communication which is close to the wireless power transfer system. Under this, a coupling capacitor helps to transfer power between transmitter and receiver plates. The utility grid voltage is converted into DC voltage using a rectifier. Then, this DC voltage is converted into AC voltage of high-frequency using an inverter circuit. Lastly, this is transferred from one side plate to another of the CPT system.  

Dynamic Wireless EV Battery Charging Technique

This technique utilizes only an inductive method for transferring power. The ICPT method can also be used in dynamic EV battery charging. Here, the primary side of the magnetic coupled network is placed in the charging system and secondary side is placed in the electric vehicle. The EV battery is charged when the vehicle is in running condition. This system helps in the reduction of the size and weight of EV batteries. As this system is used in the roadway so people can come in contact with the electromagnetic radiations. To ensure safety, it is necessary to take the permissible limit of radiation while designing the system.   

Conclusion

So, these were the two Wireless Power Transfer topologies for charging an EV battery. After focussing on aspects such as different types of ferrite cores, compensation, converters, and controllers, we can say that the ICPT Technique is ideal for designing an efficient EV battery charging system. Alisha Coils & Transformers is a global supplier of ferrite core transformers and wound magnetic components that are used for manufacturing EV battery charging systems. You can contact their technical support team for any enquiry or guidance.