A kind of lc resonance frequency search circuit and search method

Abstract

The invention discloses an LC resonant frequency search circuit, which includes an output of an amplitude modulation detector connected to a data acquisition and recording circuit, an output of the data acquisition and recording circuit connected to a comparison, judgment and control circuit, and the output of the comparison, judgment and control circuit is simultaneously connected Programmable frequency synthesizer, data acquisition and recording circuits. The output of the programmable frequency synthesizer is connected to the gate driver, the output of the gate driver is connected to the current switch, the output of the current switch is connected to one end of the resonant capacitor, and the other end of the resonant capacitor is connected to one end of the resonant inductor and the input of the AM detector, the resonant inductor The other end is connected to the current switch. The resonant inductor is coupled with the inductor through the space electromagnetic field, and the coupled inductor is connected to the equivalent impedance. The device enables the production of the resonant LC drive circuit for electromagnetic induction energy transmission to realize the non-adjustment of L and C parameters, the energy conversion efficiency is always at the highest state, and can reduce its variation with temperature.

Description

technical field [0001] The invention belongs to the technical field of analog and digital mixed signal integrated circuits, and in particular relates to an LC resonant frequency search circuit and a search method. Background technique [0002] In the electromagnetic induction energy transmission circuit, the electromagnetic wave transmitting coil must work in the resonance step, so as to transmit energy efficiently. In order to ensure the accuracy of the resonance frequency, the main measures taken in the prior art are as follows: [0003] The first is to use high-precision instruments to manually screen devices with basically consistent parameters from existing commercial LC devices, for example, use a precision bridge to select qualified products from existing commercial LC devices, so that the error of device parameter values ​​​​is within 1%. , to ensure that the system resonance frequency error is within 2.5%, this method is often used in laboratory research and small-...

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Problems solved by technology

[0004] The second method is to entrust device manufacturers to produce high-precision dedicated LC devices. This method needs to improve the existing production process and increase testing equipment. The cost is high, but it is conducive to mass production

[0005] The third is to reserve pads and space on the PCB, and use capacitors in series and parallel for on-site matching on the production line. For example, a positive error L and a negative error C are combined to form a resonant frequency that meets the requirements, or Adjust the resonant frequency by adjusting the position of the magnetic core. This method requires more stations and reduces production efficiency. It is suitable for small batch production

[0006] Among the three common solutions above: Although the first solution is simple and easy to implement, the highest nominal accuracy of commercialized capacitors and inductors is only 5% at present. It is necessary to screen qualified devices from a large number of LC devices and deal with a large number of unqualified ones. Devices are time-consuming and labor-intensive, and the cost is too high; Option 2 requires custom-made high-precision LC devices. Although the quality can be guaranteed, it increases the cost of finished products and reduces market competitiveness; Option 3 requires more stations on the assembly line, which reduces production efficiency. , poor product consistency

[0007] Therefore, the current solutions are not suitable for overcoming the resonance frequency shift caused by the parasitic reactance on the circuit board, nor can it eliminate the resonance frequency shift caused by the LC parameters changing with temperature. The existing technology is difficult to meet the production needs of large quantities and low cost.

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