CN107656133B - Method and device for detecting resonant current of transmitting end of wireless charging system - Google Patents
Method and device for detecting resonant current of transmitting end of wireless charging system Download PDFInfo
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Abstract
The invention relates to a method and a device for detecting resonant current of a transmitting end of a wireless charging system, which are used for acquiring a current signal of a previous period to obtain a signal period T; according to the signal period T, calculating the corresponding time of the phase to be measured in the previous period
Adding the signal period T to obtain the corresponding time of the phase to be measured in the current period
Collecting
And obtaining the current value of the phase to be measured in the current period by the current signal at the moment. The invention has simple realization and higher real-time property, can quickly lock the frequency, the amplitude and the effective value of the current high-frequency resonant current, and further can participate in the control and the protection of a wireless charging system.
Description
Technical Field
The invention belongs to the technical field of wireless charging, and particularly relates to a method and a device for detecting resonant current of a transmitting end of a wireless charging system.
Background
At present, wireless charging adopts radio wave and electromagnetic induction technology, current is induced and generated through a coil in a wireless charger and a coil in equipment to be charged, the induced current is converted into an electromagnetic wave signal, and after the electromagnetic wave signal is transmitted to the equipment to be charged from the wireless charger, the received electromagnetic wave signal is converted into a direct current power supply used for charging the equipment through a receiving device in the equipment to be charged, so that the battery of the equipment is charged.
Fig. 1 shows a structure diagram of a wireless charging system, and the transmission mechanism thereof is as follows: when the LC self-resonance frequency of the transmitting end is consistent with the switching frequency of the inverter power supply, the transmitting end LC is in the working state with the strongest resonance, and at the moment, if the LC self-resonance frequency of the receiving end is consistent with the resonance frequency, the L of the receiving end and the L of the transmitting end can generate strong magnetic coupling, namely the condition of wireless power transmission is met.
The energy transmission of the wireless charging transmitting end is mainly realized by full-bridge inversion by using power electronic devices, and the switching frequency is generally between 20kHz and 100 kHz. The detection of the resonant current of the transmitting end of the wireless charging system is an indispensable part in the wireless charging power transmission, the frequency, the effective value and the amplitude of the resonant current are used as control objects, and the frequency regulation and the duty ratio regulation can be conveniently realized by controlling the switch tube, so that the frequency tracking and the power control are realized. Therefore, the real-time performance and the accuracy of updating the frequency, the effective value and the amplitude value of the system directly influence the setting of the control parameters of the whole system and the stability of the performance.
The detection method for the frequency, the amplitude and the effective value of the resonant current of the transmitting end of the wireless charging system at home and abroad mainly adopts a software detection method. Software detection mainly calculates a real part and an imaginary part of a fundamental wave of the resonant current through acquisition of a fixed point in a single period by a Fourier algorithm, so as to obtain amplitude and phase information of the resonant current, but the current period of the fundamental wave is required to be known, so that the sampling interval time of the resonant current can be divided according to the number of acquisition points of the Fourier algorithm, and the current frequency is obtained by an external frequency locking device; the resonant current is a high-frequency signal, the sampling time interval is limited by the sampling rate of the sampling chip, the cost of the sampling chip is indirectly increased, meanwhile, the implementation of a Fourier algorithm is complex, the requirement on the operation speed of the control chip is high, and the general control chip cannot meet the requirements on the operation and the real-time performance of the general control chip; in conclusion, software detection has the defects of high requirements on sampling rate and control chip operation rate, complex algorithm realization and the like.
Disclosure of Invention
The invention aims to provide a method and a device for detecting resonant current of a transmitting end of a wireless charging system, which are used for solving the problems of complex algorithm and high requirement on a control chip when resonant current information is detected in the prior art.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the invention provides a method for detecting resonant current of a transmitting end of a wireless charging system, which comprises the following method schemes:
the first method scheme comprises the following steps:
collecting a current signal of a previous period to obtain a signal period T;
according to the signal period T, calculating the corresponding time of the phase to be measured in the previous period
Adding the signal period T to obtain the corresponding time of the phase to be measured in the current period
Collecting
And obtaining the current value of the phase to be measured in the current period by the current signal at the moment.
In a second method, on the basis of the first method, the current value of the phase to be measured in the current cycle includes an effective value of the current and/or an amplitude of the current.
In a third method, on the basis of the first method, the acquiring the current signal of the previous period to obtain the signal period T includes:
collecting a current signal of a previous period, and converting the current signal into a rectangular pulse with a phase consistent with that of the current signal;
and obtaining the signal period T according to the interval duration of the rising edge or the falling edge of the rectangular pulse.
Method scheme four, on the basis of method scheme two, the acquisition
The current signal at the moment, and the obtaining of the current value of the phase to be measured in the current period, includes:
collecting
The current signal at the moment is the effective value of the current of the phase to be measured in the current period;
according to the effective value of the current of the phase to be measured in the current period, calculating the sine value of the phase to be measured, and obtaining the amplitude value of the current of the phase to be measured in the current period:
wherein, ImAmplitude of the current of the phase to be measured of the current cycle, IrmsIs the effective value of the current of the phase to be measured of the current cycle,
in order to measure the phase position of the phase,
the sine value of the phase to be measured is obtained.
In the fifth method, on the basis of the first method, the time corresponding to the previous cycle of the phase to be measured is:
wherein the content of the first and second substances,
t is the signal period for the phase to be measured,
the phase to be measured corresponds to the time of the previous period.
The invention also provides a device for detecting the resonant current of the transmitting end of the wireless charging system, which comprises the following device scheme:
the device comprises a first device scheme and a second device scheme, wherein the first device scheme comprises an acquisition module and a controller;
the acquisition module is used for acquiring a current signal of the previous period and
a current signal at a time;
the controller is used for calculating the corresponding moment of the phase to be measured in the previous period according to the signal period T
Adding the signal period T to obtain the corresponding time of the phase to be measured in the current period
And collected according to a collection module
And the current signal at the moment obtains the current value of the phase to be measured in the current period.
And in a second device scheme, on the basis of the first device scheme, the current value of the phase to be measured in the current period comprises an effective value of the current and/or an amplitude value of the current.
The device scheme III is based on the device scheme I, and further comprises a conversion module, wherein the conversion module is used for converting the current signal of the previous period acquired by the acquisition module into a rectangular pulse with the same phase as the current signal of the previous period; the processor is further used for obtaining the signal period T according to the interval duration of the rising edge or the falling edge of the rectangular pulse.
And on the basis of the third device scheme, the conversion module comprises a comparator, the in-phase input end of the comparator is used for being connected with the output end of the acquisition module, the reverse-phase input end of the comparator is grounded through a resistor, and the output end of the comparator is used for being connected with the controller.
And on the basis of the fourth device scheme, the output end of the comparator is connected with the controller through an optical coupling isolation element.
And on the basis of the fifth device scheme, the output end of the acquisition module is connected with the non-inverting input end of the comparator sequentially through the voltage follower and the amplifier.
And a seventh device scheme, wherein on the basis of the first device scheme, the controller comprises a DSP and an FPGA.
The device scheme eight, on the basis of the device scheme two, the controller is used for collecting
The current signal at the moment, and the obtaining of the current value of the phase to be measured in the current period, includes:
collecting
The current signal at the moment is the effective value of the current of the phase to be measured in the current period;
according to the effective value of the current of the phase to be measured in the current period, calculating the sine value of the phase to be measured, and obtaining the amplitude value of the current of the phase to be measured in the current period:
wherein, ImAmplitude of the current of the phase to be measured of the current cycle, IrmsIs the effective value of the current of the phase to be measured of the current cycle,
in order to measure the phase position of the phase,
the sine value of the phase to be measured is obtained.
And on the basis of the first device scheme, the time corresponding to the previous period of the phase to be measured is as follows:
wherein the content of the first and second substances,
t is the signal period for the phase to be measured,
the phase to be measured corresponds to the time of the previous period.
The invention has the beneficial effects that:
according to the method and the device for detecting the resonant current of the transmitting end of the wireless charging system, based on the thought that the resonant current frequency cannot change suddenly in adjacent periods and the real-time value, the phase angle, the amplitude and the effective value of the trigonometric function are related, the phase moment to be detected in the previous period is obtained according to the period of the resonant current signal in the previous period, the phase moment to be detected in the current period is further obtained, the trigger signal is output to the sampling module to start sampling at the phase moment to be detected in the current period, and the current at the phase moment to be detected in the current resonant period can be obtained. The method is simple to implement, high in real-time performance, capable of quickly locking the frequency, the amplitude and the effective value of the current high-frequency resonant current, easy to implement and capable of participating in control and protection of the wireless charging system.
Further, the acquired transmitting end resonant current signal is converted into a rectangular pulse with the same phase, and the period and the frequency of the resonant current are obtained through the interval duration of the rising edge or the falling edge of the rectangular pulse. The method is simple, easy to implement and low in cost.
Drawings
Fig. 1 is a schematic diagram of a resonant current detection device at a transmitting end of a wireless charging system according to the present invention;
fig. 2 is a schematic circuit diagram of a conversion module in the resonant current detection device of the transmitting terminal of the wireless charging system according to the present invention;
fig. 3 is a flowchart of a method for detecting a resonant current at a transmitting end of a wireless charging system according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.
Referring to fig. 1, a schematic diagram of a resonant current detection device for a transmitting terminal of a wireless charging system according to the present invention is shown, wherein the resonant current detection device is arranged between L, C of the transmitting terminal, includingThe collection module is connected with the conversion module, and the conversion module is connected with the controller; the acquisition module is used for acquiring the current signal of the previous period
A current signal at a time; the conversion module is used for converting the current signal of the previous period acquired by the acquisition module into a rectangular pulse with the same phase as the current signal of the previous period; the processor is used for obtaining a signal period T according to the interval duration of the rising edge or the falling edge of the rectangular pulse, and is also used for calculating the time corresponding to the previous period of the phase to be measured according to the signal period T
Adding the signal period T to obtain the corresponding time of the phase to be measured in the current period
And collected according to a collection module
And the current signal at the moment obtains the current value of the phase to be measured in the current period.
When the wireless charging system meets the wireless charging condition, the detection device collects the resonant current of the transmitting end of the wireless charging system through the current transformer, conditions the signal through the circuit shown in figure 3, and sends the conditioned signal to the controller for calculation. The TMS320F28335 and XC6SLX9-2FTG256I of TI are used as control chips of the wireless charging system, the working dominant frequency reaches 150MHz, and the calculation of various digital control algorithms can be completed in a fast and real-time manner.
As shown in fig. 3, the conversion module includes a first op-amp U2, a second op-amp U1A, a third op-amp U1B, and an isolation optocoupler U3. The first operational amplifier U2 and its peripheral circuit form a comparator, the second operational amplifier U1A and its peripheral circuit form a voltage follower, and the third operational amplifier U1B and its peripheral circuit form an amplifier.
The resonance current of the transmitting end of the wireless charging system to be collected is firstly followed by the voltage following circuit, and the signal is buffered, isolated and the load capacity is improved. The voltage follower circuit includes a second op amp U1A. A resonant current signal of an emitting end of the wireless charging system is connected to a non-inverting input end of a second operational amplifier U1A through a current limiting resistor R1, an output end of a second operational amplifier U1A is connected to a non-inverting input end of a third operational amplifier U1B through a resistor R2, and an output end of the second operational amplifier U1A is further connected to an inverting input end of a second operational amplifier U1A. The positive power supply end of the second operational amplifier U1A is connected with VCC +5.0V, the positive power supply end is further connected with a grounding capacitor C2, the reverse power supply end of the second operational amplifier U1A is connected with VCC-5V, and the reverse power supply end is further connected with a grounding capacitor C1. The second op-amp U1A may employ AD8066 AR.
Then, the following signal is sent to an amplifier, the signal output by the voltage follower is amplified by two times, and the amplified signal is in phase with the resonance current. The amplifier comprises a third operational amplifier U1B, wherein the output end of the third operational amplifier U1B is connected with the non-inverting input end of a first operational amplifier U2 through a resistor R6, the output end of the third operational amplifier U1B is also connected with the inverting input end of a first operational amplifier U2 through a resistor R5, the inverting input end of the first operational amplifier U2 is also grounded through a resistor R3, and a capacitor C3 is connected between the inverting input end and the non-inverting input end of a first operational amplifier U2. The third op-amp U1B may also employ AD8066 AR.
Then, the amplified signal is passed through a comparator to convert the sine wave into a square wave of the same phase. The comparator comprises a first operational amplifier U2, the inverting input end of the first operational amplifier U2 is grounded through a resistor R7, and the output end of the first operational amplifier U2 is connected with the primary side pin 1 of an isolation optocoupler U3 through a resistor R8; the negative power supply end of the first operational amplifier U2 is connected with-5V and is also grounded through a capacitor C4; the positive power terminal of the first operational amplifier U2 is connected to VCC +5.0V and is also grounded through a capacitor C5. The first handler U2 may employ TL3016 ID.
And finally, the signal converted into the square wave is sent to pin 1 of the optical coupling isolation U3 through a resistor R3, and pin 5 of the output end of the optical coupling isolation U3 is sent to the FPGA through a current limiting resistor R11.
Based on the circuit, the acquired transmitting end resonant current signal can be converted into a rectangular pulse consistent with the phase of the signal. On the basis, the frequency, the amplitude and the effective value of the resonance current can be calculated. Specifically, the method comprises the following steps:
1) after the FPGA detects a square wave signal sent by a conditioning circuit of the resonant current of the wireless charging transmitting terminal, the frequency f of the resonant current in the previous period is 2 pi/T by calculating the period value T of the previous period through the rising edge and falling edge of the signal.
2) Because the resonant current frequency can not change suddenly in the adjacent period, the period value of the current period and the period value of the previous period can be approximately regarded as the same, and the period T of the resonant current signal of the previous resonant period is obtained and is also T.
3) Calculating the corresponding time t of the previous period of 45 degrees of phase to be measured45°And then, adding the period T to obtain the time corresponding to the current period of 45 degrees:
4) when the FPGA detects that the time in the current period is equal to t45°When the real-time value I of the resonant current of the transmitting end is acquired, the FPGA outputs a pulse signal to the DSP, and the DSP is triggered to acquire the real-time value I of the resonant current of the transmitting end by an ADC (analog to digital converter) sampling module45°The value is the effective value I of the current resonance currentrmsNamely:
Irms＝I45°
5) due to the amplitude I of the present resonant currentmMultiplying sin 45 DEG to the effective value I of the current resonance currentrmsTherefore, the amplitude of the present resonant current can be obtained, namely:
besides FPGA and DSP, other control chips can be used to calculate frequency, effective value and amplitude.
As another embodiment, triggering the AD module to sample the current real-time value of the resonant current at 30 ° of the resonant current period may also be adopted.
Or, an external AD sampling chip can be triggered to acquire a real-time value of the resonant current of the wireless charging transmitting terminal.
While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.
Claims (10)
1. A method for detecting a resonant current of a transmitting end of a wireless charging system is characterized by comprising the following steps:
collecting a current signal of a previous period to obtain a signal period T;
according to the signal period T, calculating the corresponding time of the phase to be measured in the previous period
Adding the signal period T to obtain the corresponding time of the phase to be measured in the current period
Collecting
Obtaining the current value of the phase to be measured in the current period according to the current signal at the moment;
the collecting of the current signal of the previous period to obtain the signal period T includes:
collecting a current signal of a previous period, and converting the current signal into a rectangular pulse with a phase consistent with that of the current signal;
obtaining a signal period T according to the interval duration of the rising edge or the falling edge of the rectangular pulse;
the time corresponding to the phase to be measured in the previous period is as follows:
wherein the content of the first and second substances,
t is the signal period for the phase to be measured,
the phase to be measured corresponds to the time of the previous period.
2. The method according to claim 1, wherein the current value of the phase to be measured in the current cycle includes an effective value of a current and/or an amplitude of a current.
3. The method of claim 2, wherein the collecting is performed by a wireless charging system transmitting end resonant current detection method
The current signal at the moment, and the obtaining of the current value of the phase to be measured in the current period, includes:
collecting
The current signal at the moment is the effective value of the current of the phase to be measured in the current period;
according to the effective value of the current of the phase to be measured in the current period, calculating the sine value of the phase to be measured, and obtaining the amplitude value of the current of the phase to be measured in the current period:
wherein, ImIs the current periodOf the phase to be measured, IrmsIs the effective value of the current of the phase to be measured of the current cycle,
in order to measure the phase position of the phase,
the sine value of the phase to be measured is obtained.
4. A wireless charging system transmitting end resonance current detection device is characterized by comprising an acquisition module and a controller;
the acquisition module is used for acquiring a current signal of the previous period and
a current signal at a time;
the controller is used for calculating the corresponding moment of the phase to be measured in the previous period according to the signal period T
Adding the signal period T to obtain the corresponding time of the phase to be measured in the current period
And collected according to a collection module
The current signal at the moment obtains the current value of the phase to be measured in the current period;
the device also comprises a conversion module, wherein the conversion module is used for converting the current signal of the previous period acquired by the acquisition module into a rectangular pulse with the same phase as the current signal of the previous period; the controller is further used for obtaining a signal period T according to the interval duration of the rising edge or the falling edge of the rectangular pulse;
the time corresponding to the phase to be measured in the previous period is as follows:
wherein the content of the first and second substances,
t is the signal period for the phase to be measured,
the phase to be measured corresponds to the time of the previous period.
5. The wireless charging system transmitting end resonant current detection device according to claim 4, wherein the current value of the phase to be measured of the current cycle comprises an effective value of a current and/or a magnitude of a current.
6. The device for detecting the resonant current of the transmitting end of the wireless charging system according to claim 4, wherein the converting module comprises a comparator, a non-inverting input end of the comparator is used for being connected with an output end of the collecting module, an inverting input end of the comparator is grounded through a resistor, and an output end of the comparator is used for being connected with the controller.
7. The device for detecting the resonant current of the transmitting end of the wireless charging system according to claim 6, wherein an output end of the comparator is connected to the controller through an optical coupling isolation element.
8. The device for detecting the resonant current of the transmitting end of the wireless charging system according to claim 7, wherein the output end of the acquisition module is connected to the non-inverting input end of the comparator through a voltage follower and an amplifier in sequence.
9. The wireless charging system transmitting end resonant current detection device as recited in claim 4, wherein the controller comprises a DSP and an FPGA.
10. The device as claimed in claim 5, wherein the controller is configured to collect the resonant current of the transmitting terminal of the wireless charging system
The current signal at the moment, and the obtaining of the current value of the phase to be measured in the current period, includes:
collecting
The current signal at the moment is the effective value of the current of the phase to be measured in the current period;
according to the effective value of the current of the phase to be measured in the current period, calculating the sine value of the phase to be measured, and obtaining the amplitude value of the current of the phase to be measured in the current period:
wherein, ImAmplitude of the current of the phase to be measured of the current cycle, IrmsIs the effective value of the current of the phase to be measured of the current cycle,
in order to measure the phase position of the phase,
the sine value of the phase to be measured is obtained.
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| CN106532977A (en) * | 2016-11-18 | 2017-03-22 | 许继电源有限公司 | Control device based on wireless power transmission system and wireless power transmission system |
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| CN101706527B (en) * | 2009-10-30 | 2012-01-04 | 西安交通大学 | Method for detecting arc faults based on time-frequency characteristics of high-frequency current component |
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| CN106532977A (en) * | 2016-11-18 | 2017-03-22 | 许继电源有限公司 | Control device based on wireless power transmission system and wireless power transmission system |
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