Wireless charging high-frequency current sampling system and sampling method thereof
阅读说明：本技术 一种无线充电高频电流采样系统及其采样方法 (Wireless charging high-frequency current sampling system and sampling method thereof ) 是由 宋凯 张子明 姜金海 梁策 张航 逯仁贵 朱春波 于 2020-07-13 设计创作，主要内容包括：本发明是一种无线充电高频电流采样系统及其采样方法。本发明属于无线电能传输技术领域,所述系统包括：DSP处理器、电流互感器、输入采集模块、偏置与信号放大模块和电压跟随模块；通过电流互感器采集电路中的高频交流电流,偏置与信号放大模块对输入信号进行放大,放大后的信号输入至电压跟随模块中,起到缓冲作用,将缓冲后的信号再次输入至输入采集电路中,由输入采集模块输入至DSP处理器中完成电流硬件采样；所述输入采集模块输出量输入至DSP处理器中的ADC模块进行电流采样,经电流采样处理后输入至DSP处理器中,进行高频电流采样。本专利提出的方法具有精度高、速度快、系统结构简单等优点。(The invention discloses a wireless charging high-frequency current sampling system and a sampling method thereof. The invention belongs to the technical field of wireless power transmission, and the system comprises: the device comprises a DSP (digital signal processor), a current transformer, an input acquisition module, a bias and signal amplification module and a voltage following module; the input signal is amplified by a bias and signal amplification module through high-frequency alternating current in a current transformer acquisition circuit, the amplified signal is input into a voltage following module to play a buffering role, the buffered signal is input into an input acquisition circuit again, and the buffered signal is input into a DSP (digital signal processor) by an input acquisition module to finish current hardware sampling; the output quantity of the input acquisition module is input to an ADC module in the DSP processor for current sampling, and the current is input to the DSP processor after current sampling processing for high-frequency current sampling. The method provided by the patent has the advantages of high precision, high speed, simple system structure and the like.)
1. A wireless high frequency current sampling system that charges, characterized by: the system comprises: the device comprises a DSP (digital signal processor), a current transformer, an input acquisition module, a bias and signal amplification module and a voltage following module;
the DSP processor control signal data signal input end is connected with the input acquisition module data signal output end, the current transformer data signal output end is connected with the input acquisition module data signal input end, the input acquisition module control signal output end is connected with the control signal input end of the bias and signal amplification module, the control signal output end of the bias and signal amplification module is connected with the control signal input end of the voltage following module, and the data signal output end of the voltage following module is connected with the input acquisition module.
2. The wireless charging high-frequency current sampling system according to claim 1, characterized in that: the voltage following module employs OPA340 and the bias and signal amplification module employs INA 128.
3. A wireless charging high-frequency current sampling method based on the wireless charging high-frequency current sampling system of claim 1, characterized in that: the method comprises the following steps:
step 1: alternating current in the circuit is acquired through the current transformer, and is input to the offset and signal amplification module after being subjected to amplitude limiting and low-pass filtering through the input acquisition module;
step 2: the bias and signal amplification module amplifies an input signal, and inputs the amplified signal to the voltage following module for signal conditioning;
and step 3: inputting the collected signal into the input collection circuit again, and inputting the collected signal into the DSP processor by the input collection module to finish current hardware sampling;
and 4, step 4: the output quantity of the input acquisition module is input to an ADC module in the DSP processor for current sampling, and the current is input to the DSP processor after being sampled and processed for output constant current control.
4. The wireless charging high-frequency current sampling method according to claim 3, characterized in that: carrying out interval breakpoint on the collected current, wherein the initial collection point is alpha, the termination collection point is b, carrying out n equal division on the collected input current, determining step length h, and node xkMean evenly inserted node xk+1/2Node xkCorresponding sine function value f (x)k) Mean value evenly inserted node xk+1/2Corresponding sine function value f (x)k+1/2)，k＝1,2,…n-1；
Determining sine function value f (x) of each nodek) Is denoted as sum1(ii) a Uniformly inserting the mean value into the node sine function value f (x)k+1/2) The sum is denoted sum 2; the integrated value S is calculated by using the simpson algorithm, and is expressed by the following formula:
wherein f (alpha) is a starting collection point function, and f (b) is a terminating collection point function;
acquiring the amplitude voltage Um according to the integral value S, and solving the amplitude voltage Um through the following formula:
wherein T is a sampling period, f is frequency, and T is time;
and determining the collected current according to the amplitude voltage to finish current sampling.
5. The wireless charging high-frequency current sampling method according to claim 3, characterized in that: the sampling delay is controlled within 0.25 period.
Technical Field
The invention relates to the technical field of wireless power transmission, in particular to a wireless charging high-frequency current sampling system and a sampling method thereof.
Background
Nowadays, wireless charging technology is rapidly developing. The wireless charging technology enables the working equipment to be separated from the constraint of the wire when the working equipment moves, the problems of heating, aging, accidental electric shock of people and the like of the wire are avoided, the wireless charging device is safe and reliable to operate, and can be applied to occasions where electric energy transmission cannot be achieved due to the fact that the wire is limited, such as electric automobiles, implanted medical electronic equipment, industrial robots, underwater detection equipment, household electronic equipment and the like. The appearance of the wireless charging technology brings great convenience to production and life of people. In the technical field of wireless charging, in order to realize output constant current control, high-frequency current in a system is generally required to be collected, converted into effective value voltage and then input into an MCU (microprogrammed control unit) for subsequent control. Therefore, the acquisition time of the high-frequency current influences the analysis speed of the MCU, so that the response time of the output constant current is influenced, and the response time is prolonged and cannot meet the corresponding technical requirements. How to shorten the acquisition time of the effective value of the output high-frequency current is always a problem of industrial research. However, in the conventional technology, the complexity of the overall design is increased and the cost is high to ensure a fast acquisition speed.
Disclosure of Invention
The invention provides a wireless charging high-frequency current sampling system and a sampling method thereof for realizing rapid high-frequency current sampling, and the invention provides the following technical scheme:
a wireless charging high-frequency current sampling system, the system comprising: the device comprises a DSP (digital signal processor), a current transformer, an input acquisition module, a bias and signal amplification module and a voltage following module;
the DSP processor control signal data signal input end is connected with the input acquisition module data signal output end, the current transformer data signal output end is connected with the input acquisition module data signal input end, the input acquisition module control signal output end is connected with the control signal input end of the bias and signal amplification module, the control signal output end of the bias and signal amplification module is connected with the control signal input end of the voltage following module, and the data signal output end of the voltage following module is connected with the input acquisition module.
Preferably, the voltage following module employs OPA340, and the bias and signal amplification module employs INA 128.
A wireless charging high-frequency current sampling method comprises the following steps:
step 1: alternating current in the circuit is acquired through the current transformer, and is input to the offset and signal amplification module after being subjected to amplitude limiting and low-pass filtering through the input acquisition module;
step 2: the bias and signal amplification module amplifies an input signal, and inputs the amplified signal to the voltage following module for signal conditioning;
and step 3: inputting the collected signal into the input collection circuit again, and inputting the collected signal into the DSP processor by the input collection module to finish current hardware sampling;
and 4, step 4: the output quantity of the input acquisition module is input to an ADC module in the DSP processor for current sampling, and the current is input to the DSP processor after being sampled and processed for output constant current control.
Preferably, interval break points are carried out on the collected current, the initial collection point is alpha, the termination collection point is b, the collected input current is equally divided by n, the step length h and the node x are determinedkMean evenly inserted node xk+1/2Node xkCorresponding sine function value f (x)k) Mean value evenly inserted node xk+1/2Corresponding sine function value f (x)k+1/2)，k＝1,2,…n-1；
Determining sine function value f (x) of each nodek) Is denoted
wherein f (alpha) is a starting collection point function, and f (b) is a terminating collection point function;
acquiring the amplitude voltage Um according to the integral value S, and solving the amplitude voltage Um through the following formula:
wherein T is a sampling period, f is frequency, and T is time;
and determining the collected current according to the amplitude voltage to finish current sampling.
Preferably, the sampling delay is controlled within 0.25 period.
The invention has the following beneficial effects:
the integral of the absolute value of the half period of the sine quantity is proportional to the amplitude Um, so that the integral value of any half period of the sine quantity can represent the effective value of the complete period of the current sine quantity. The invention can realize the sampling speed faster than the single signal period by using the sampling circuit and the algorithm, and ensure that the system realizes the single signal period control. Compared with the problems that the corresponding speed is low due to traditional multi-period sampling, the operation amount is large due to complete period sampling, the system is complex and not easy to realize, and the like, the method provided by the patent has the advantages of high precision, high speed, simple system structure and the like.
Drawings
FIG. 1 is a block diagram of a wireless charging high frequency current sampling system;
FIG. 2 is a schematic diagram of an input acquisition module;
FIG. 3 is a schematic diagram of an offset and signal amplification module;
FIG. 4 is a schematic diagram of a voltage follower module;
fig. 5 is a flow chart of a method for sampling high-frequency current of a wireless charging system;
fig. 6 is a graph of the effect of current sampling of the coil at the transmitting end.
Detailed Description
The present invention will be described in detail with reference to specific examples.