**4. Practical design approach for industrial wireless power transfer charging system**

#### **4.1 Power electronic system configuration**

Electrical engineers responsible for the design of the wireless transfer chargers must consider standard grid network connection during design process. Because many issues are nowadays address on the quality of the supply grid, the main goal during design of any power electronic system is to achieve the best performance related to the power factor parameter at any power consumption of the system. In addition to this fact, it is also required to have fully symmetrical 3-phase current with as low total harmonic distortion as possible [25–28].

$$\text{THDi} = \frac{\sqrt{\sum\_{\mu=2} i\_{ac(\mu)}^2}}{i\_{ac(1)}} \mathbf{100} \tag{54}$$

example), followed by the active PFC/THDC rectifier supplying the voltage source inverter (VSI). For both cases (low or high power) the VSI is sourcing primary/ transmitting coil with relevant compensation. This configuration of power electronic system (**Figure 19** – orange blocks) is providing low ripple input current with sinusoidal character, low THDi, excellent power factor and controllable output voltage. Therefore, it is not required to implement another dc/dc converter stage

The recommended topologies are summarized in **Figure 19** according to system

The concept of power electronic system for the secondary side also differs based

A more detailed example above described solution, which could meet all necessary technical requirements on high power applications and simultaneously having

on the type of the load, and level of the power delivery. Basically, it consists of secondary side coil equipped by relevant compensation, passive or active rectifier

and dc/dc converter stage providing required functionality of the charger. Finally, the system connection to the grid considering all the power levels established as WPT categories by SAE TIR J2954 is seen in conceptual layout shown

in **Figure 20**, valid especially for central Europe [32–35].

*Theoretical and Practical Design Approach of Wireless Power Systems*

*DOI: http://dx.doi.org/10.5772/intechopen.95749*

excellent operational properties, is seen in **Figure 21**.

within the system [29–31].

dedicated power level.

**Figure 20.**

**Figure 21.**

**63**

*WPT system categories – Connection to the grid.*

*Recommended system configuration for high power application.*

Regarding above mentioned facts, each power electronic system, which must undergo strict normative given on the qualitative indicators of the grid variables, must be equipped with input active or passive power factor corrector (PFC) and total harmonic distortion correction (THDC). These blocks are consequently followed by diode rectifier, dc/dc converter (step-up or step-down) and the voltage source inverter. Such power electronic system configuration is robust and verified by many similar applications (mostly power supplies and battery chargers). The main negative drawback of such concept lies in higher price and build-in dimensions along with the increase in power rating. This topology should therefore be recommended for low or medium power WPT chargers (**Figure 19** – blue blocks).

Second group of WPT chargers considering the value of power delivery is medium to high power concepts. Here it is recommended to use the configuration composed of input filter (inductive – designed as distribution transformer for

#### **Figure 19.**

*Power electronics configuration on the primary side of the wireless power charger indicating differences related to the level of the power transfer.*
