Coupling coefficient in wireless charging (power supply)
Release Time:
2024-06-18
Based on the distance between the transmitting coil and the receiving coil, only a small portion of the magnetic flux generated by the transmitting coil will penetrate the receiving coil and facilitate power transmission. The more magnetic flux reaches the receiver, the better the coil coupling effect. The tightness of coupling is represented by the "k value", which is the "coupling coefficient".
Based on the distance between the transmitting coil and the receiving coil, only a small portion of the magnetic flux generated by the transmitting coil will penetrate the receiving coil and facilitate power transmission. The more magnetic flux reaches the receiver, the better the coil coupling effect. The tightness of coupling is represented by the "k value", which is the "coupling coefficient".
The coupling coefficient "k value" ranges from 0 to 1, where 1 represents complete coupling, meaning that all magnetic flux generated by Tx passes through Rx. On the contrary, 0 represents that there was no coupling between the Tx and Rx coils in the system before.
The coupling coefficient is determined by the distance and relative size between the inductors (Tx and Rx coils), as well as the shape of the coils and the angle between them. As shown in the figure below, the coupling coefficient between flat coils with a diameter of 30mm is used to illustrate the coupling coefficients of two parallel coil coils at different axial distances and horizontal offsets. When the coils are axially aligned, an increase in the distance between the coils will lead to a decrease in the value of k; Within a certain distance range, when the distance between coils is fixed, an increase in horizontal displacement between coils will also lead to a decrease in k value. From the figure, it can also be seen that 0.3 to 0.6 are typical k values between the two coils in the example.
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