Metallic foreign object detection device and method for high-power swpit system

Abstract

The present application relates to the technical field of metal foreign matter detection, and particularly relates to a metal foreign matter detection device and method of a high-power SWPIT system, comprising: a power-transmission-adjustable data communication system, an energy coupling system, and a magnetic control switch module; the data communication system comprises a primary-side data transceiving circuit and a secondary-side data transceiving circuit with adjustable power levels; one end of the primary-side data transceiving circuit and one end of the secondary-side data transceiving circuit are respectively connected to two ends of the magnetic control switch module; through cooperation of the data communication system, the energy coupling system, and the magnetic control switch module, the data communication system transmits data signals through high-frequency carrier waves; during data transmission, a coupling link is shared by data transmission and power transmission; when foreign matter appears, the foreign matter affects both data transmission and power transmission, so that the existence of the foreign matter can be more sensitively sensed, interference on foreign matter detection signals is reduced, and the accuracy of foreign matter detection is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal foreign matter detection, and particularly relates to a metal foreign matter detection device and method of a high-power SWPIT system. BACKGROUND

[0002] The high-power SWPIT system is a wireless power and information synchronous transmission system combining wireless energy transmission and wireless information transmission functions to realize real-time information exchange between a transmitter and a receiver; in industrial production, the existence of metal foreign matters may cause the metal foreign matters to be embedded into the produced products or enter the equipment, affecting the normal operation of the equipment; in order to ensure the continuous operation of the production line and reduce downtime, metal foreign matter detection needs to be performed on the high-power SWPIT system.

[0003] At present, the metal foreign matter detection method for the high-power SWPIT system is usually to detect the foreign matters by measuring the change of the magnetic flux of the detection coil and the induced voltage; although the relative position between the detection coil and the transmitting coil is fixed, the influence of the coupling effect on the parameters of the detection coil is fixed, but in a high-power density environment, the strong coupling between the transmitting coil and the receiving coil may still cause non-negligible interference to the detection coil, affecting the accuracy of the detection result, therefore, we need to propose a metal foreign matter detection device and method of a high-power SWPIT system to solve the above problems, so that the existence of foreign matters can be more sensitively perceived, the interference to the foreign matter detection signal is reduced, and the accuracy of the foreign matter detection is improved. SUMMARY

[0004] In view of the above problems, the application provides a metal foreign matter detection device of a high-power SWPIT system, which comprises a power transmission adjustable data communication system, the data communication system comprises a primary side data transceiving circuit and a secondary side data transceiving circuit with adjustable power levels, and the primary side data transceiving circuit and the secondary side data transceiving circuit each comprise a signal sending module and a signal receiving module.

[0005] An energy coupling system, the energy coupling system comprises an energy transmitting coil and a secondary side power receiving coil.

[0006] A magnetic control switch module, the magnetic control switch module comprises a detection trigger unit for foreign matter detection and a control response unit for on-off control.

[0007] One end of the primary side data transceiving circuit and one end of the secondary side data transceiving circuit are connected to two ends of the magnetic control switch module, respectively, the other end of the primary side data transceiving circuit is connected to the energy transmitting coil, and the other end of the secondary side data transceiving circuit is connected to the secondary side power receiving coil.

[0008] The primary side data transceiving circuit and the secondary side data transceiving circuit transmit data signals through high frequency carrier, so that the data transmission and the power transmission share a coupling link, and the foreign matter affects the data transmission and the power transmission.

[0009] Further, the signal sending module and the signal receiving module on the primary side are connected in parallel to the energy transmitting coil, and the signal sending module and the signal receiving module on the secondary side are connected in parallel to the secondary side power receiving coil. The primary side data transceiving circuit is responsible for modulating and transmitting data signals through high frequency carrier injection. The secondary side data transceiving circuit receives the modulated signals from the primary side and performs demodulation processing to realize data communication between the primary side and the secondary side. The primary side data transceiving circuit and the secondary side data transceiving circuit are connected in parallel to the energy transmitting coil and the secondary side power receiving coil, so that they share a coupling link for data transmission.

[0010] Further, the primary side data transceiving circuit modulates the data to be transmitted as follows:

[0011] A1, set the baseband signal as m(t), and the high frequency carrier signal as A c cos(w c t), wherein A c is the carrier amplitude before modulation, w c is the carrier angular frequency;

[0012] A2, calculate the modulation index k a according to the high frequency carrier signal, and the calculation formula is as follows:

[0013] wherein ΔA is the maximum change of the carrier amplitude;

[0014] A3, superimpose the baseband signal m(t) and the high frequency carrier signal A c cos(w c t) to obtain the modulated signal s(t), and the superimposition formula is as follows:

[0015] s(t)=A c [1+k a m(t)]cos(w c t).

[0016] Further, the secondary side data transceiving circuit demodulates the modulated signal received from the primary side as follows:

[0017] B11, receive the modulated signal s(t) from the primary side coupling;

[0018] B12, rectify the received modulated signal s(t) using a rectifier diode to obtain a rectified signal s r(t), the rectified signal has the following two cases:

[0019] When s r (t)≥0, s r (t)=s(t);

[0020] When s r (t)<0, s r (t)=0, indicating no signal;

[0021] B13, the rectified signal is filtered, and the filtering formula is as follows:

[0022]

[0023] Y(s)=H(s)*s r (t),

[0024] Where w c is the carrier angular frequency, Q is the quality factor, s is the complex frequency variable, H(s) is the transfer function of the low-pass filter, s r (t) is the rectified signal, and Y(s) is the filtered signal;

[0025] B14, the filtered signal is processed for baseband signal restoration, and the baseband signal restoration formula is as follows:

[0026] M(s)=H(s)*Y(s), where M(s) is the restored baseband signal, H(s) is the transfer function of the low-pass filter, and Y(s) is the filtered signal.

[0027] Further, the primary data transceiver circuit and the secondary data transceiver circuit share a coupling link when transmitting data and transmitting power, so that they can enter the power transmission and communication cooperative process. The power transmission and communication cooperative process is as follows:

[0028] B21, when there is no communication signal influence, calculate the transmission power P1 without communication signal influence, and the calculation formula is as follows:

[0029] P1=w1*M1*I1*I2*k1, where w1 is the working angular frequency, M1 is the mutual inductance value, I1 is the primary coil current value, I2 is the secondary coil current value, and k1 is the coupling coefficient, the value range of the coupling coefficient is 0≤k1≤1;

[0030] B22, when the data communication system adopts high-frequency carrier injection master mode to send signals, the communication signal current will be superimposed on the current of the primary coil and the secondary coil, and the total current of the primary coil is I 原 =I1+I 1C , where I 1CI1 is the primary side communication signal current, I1 is the primary side non-communication signal coil current; the total current of the secondary side coil is I 副 = I2+I 2C , wherein I 2C is the secondary side communication signal current, I2 is the secondary side non-communication signal coil current;

[0031] B23, according to the total current of the primary side coil and the total current of the secondary side coil, calculate the new transmission power P2, the calculation formula is as follows:

[0032] P2 = w1*M1*I 原 *I 副 *k1, wherein w1 is the operating angular frequency, M1 is the mutual inductance value, I 原 is the total current value of the primary side coil, I 副 is the total current value of the secondary side coil, and k1 is the coupling coefficient, the value range of the coupling coefficient is 0≤k1≤1;

[0033] B24, according to the transmission power P1 and the new transmission power P2, the amplitude of the primary side communication signal voltage U 原 and the amplitude of the secondary side communication signal voltage U 副 , the calculation formula is as follows:

[0034]

[0035] B25, according to the amplitude of the primary side communication signal voltage U 原 and the amplitude of the secondary side communication signal voltage U 副 , the attenuation of the communication signal is calculated, and the calculation formula is as follows:

[0036]

[0037] B26, according to the calculated attenuation A dB , the attenuation degree of the communication signal is judged, and there are the following two cases:

[0038] B261, when A dB =10dB, it is judged that the attenuation of the communication signal is small, and power regulation is not needed;

[0039] B262, when A dB =30dB, it is judged that the attenuation of the communication signal is large, and power regulation is needed;

[0040] The power regulation mode is as follows: according to the transmission power P1 and the new transmission power P2, the power regulation coefficient n is calculated, and the power regulation is carried out according to the power regulation coefficient n, and the power regulation coefficient n calculation formula is as follows:

[0041]

[0042] Further, the energy coupling system further comprises a DC-AC conversion unit for connecting with the DC power supply and converting the input voltage into AC signal, a compensation network unit, and a load unit, the compensation network unit is connected with the energy transmitting coil and the secondary side power receiving coil respectively, the load is connected at one end of the compensation network unit at the secondary side, and the DC-AC conversion unit is connected at one end of the compensation network unit at the primary side; the compensation network unit is used for improving the efficiency and performance of energy transmission; and the load is used for representing the consumption device after receiving the energy at the secondary side.

[0043] Further, the compensation network unit adjusts the resonance characteristics of the circuit by connecting the capacitor C1 in series with the energy transmitting coil and connecting the capacitor C2 in series with the secondary side power receiving coil, so as to achieve better energy coupling effect; and the flow of adjusting the resonance characteristics of the compensation network unit is as follows.

[0044] C11, the primary side resonance frequency when the primary side is connected in series with the compensation is calculated according to the capacitor C1 connected in series with the primary side and the inductance value of the energy transmitting coil at the primary side, and the calculation formula is as follows:

[0045] Wherein, w0 is the calculated primary side resonance frequency, L1 is the inductance value of the energy transmitting coil at the primary side, and C1 is the capacitance value of the capacitor C1 connected in series.

[0046] C12, when the working frequency of the circuit is equal to the primary side resonance frequency w0, the circuit resonates, at this time, the equivalent impedance of the primary side circuit is minimum, the effective value of the primary side current at resonance is calculated according to the effective value of the power supply voltage and the equivalent impedance value of the primary side, and the calculation formula of the effective value of the primary side current is as follows:

[0047] Wherein, i 1r is the effective value of the primary side current, U ac is the effective value of the power supply voltage, and R1 is the effective value of the equivalent impedance of the primary side.

[0048] C13, the secondary side resonance frequency when the secondary side is connected in series with the compensation is calculated according to the capacitor C2 connected in series with the secondary side and the inductance value of the secondary side power receiving coil, and the calculation formula is as follows:

[0049] Wherein, w'0 is the calculated secondary side resonance frequency, L2 is the inductance value of the secondary side power receiving coil, and C2 is the capacitance value of the capacitor C2 connected in series.

[0050] C14, when the circuit resonates, the equivalent impedance value of the secondary side induced electromotive force in the secondary side circuit is minimum, the effective value of the secondary side current is calculated according to the secondary side induced electromotive force and the equivalent impedance value of the secondary side, and the calculation formula of the effective value of the secondary side current is as follows:

[0051] wherein I 2r is the secondary side current effective value, e2(t) is the secondary side induced electromotive force, and R2 is the secondary side equivalent impedance effective value.

[0052] Further, the detection triggering unit performs the foreign matter detection process as follows:

[0053] D11, when the system is normally running, there is a stable magnetic field distribution between the primary side and the secondary side, the initial magnetic field strength at the position of the magnetic control switch is set as B0(t), and the magnetic field strength threshold B th of the magnetic control switch is set.

[0054] D12, when foreign matter appears, the foreign matter will interfere with the magnetic field, so that the magnetic field strength at the position of the magnetic control switch becomes B(t), and the change amount ΔB(t) of the magnetic field strength is calculated, and the calculation formula is as follows: ΔB(t) = B(t) - B0(t).

[0055] D13, according to the comparison between the calculated change amount ΔB(t) of the magnetic field strength and the magnetic field strength threshold B th , there are the following two cases:

[0056] D131, when the magnetic field change amount satisfies |ΔB(t)|≥B th , the magnetic control switch will be triggered to change the state, that is, the magnetic control switch changes from the normal initial state to another state.

[0057] D132, when the magnetic field change amount satisfies |ΔB(t)|<B th , the magnetic control switch will not be triggered to change the state, that is, the magnetic control switch remains in the normal initial state.

[0058] Further, the control response unit performs the on-off control process as follows:

[0059] D21, after the state of the magnetic control switch changes, an electrical signal u out (t) will be sent to the control response unit.

[0060] D22, after the control response unit receives the electrical signal u out (t) from the magnetic control switch, it performs judgment processing according to the preset logic, if the power transmission parameters need to be adjusted, the control voltage input to the energy transmitting coil is adjusted, by changing the size or waveform of the control voltage, the primary side current can be changed, and then the power transmission situation is affected.

[0061] Based on the above description, the application further provides a metal foreign matter detection device for a high-power SWPIT system, and a metal foreign matter detection method for a high-power SWPIT system, which comprises the following steps:

[0062] S1, turn off the magnetic control switch, and close the system pipe;

[0063] S2, check whether the secondary side is connected, if not, return to S1, if connected, go to S3;

[0064] S3, the primary side magnetic control switch is closed;

[0065] S4, the primary side data transmission circuit transmits fixed data code with different power levels in multiple rounds;

[0066] S5, the secondary side data transceiver circuit receives data signals with different power levels, and judges whether the secondary side receiving circuit can correctly decode the data signals with different power levels:

[0067] If not, it is determined that there is a foreign object, and the system alarms;

[0068] If yes, go to S6;

[0069] S6, after the secondary side correctly decodes, sends a handshake signal to the primary side, and the primary side judges whether the handshake signal is received:

[0070] If not, it is determined that there is a foreign object, and the system alarms;

[0071] If yes, start power transmission, and go to S7;

[0072] S7, after the power transmission starts, the secondary side data transceiver circuit sends data signals with different power levels at regular intervals, and judges whether there is a handshake signal returned:

[0073] If not, it is determined that there is a foreign object, and the system alarms and turns off the power transmission;

[0074] If yes, keep the power transmission, and continue to detect at regular intervals, to monitor in real time whether there is a foreign object suddenly entering to affect the power transmission during the charging process.

[0075] The beneficial effects of the present application are:

[0076] 1, through the cooperation of the data communication system, the energy coupling system and the magnetic control switch module, the data communication system transmits data signals through high-frequency carrier, and the data transmission and the power transmission share a coupling link, so that when a foreign object appears, the foreign object affects both the data transmission and the power transmission, thereby more sensitively sensing the existence of the foreign object, reducing the interference on the foreign object detection signal, and improving the accuracy of the foreign object detection.

[0077] 2, the magnetic control switch module composed of the detection trigger unit and the control response unit, so that the system can adjust the power transmission according to the change of the magnetic field when a foreign object appears, to ensure the normal operation of the whole system.

[0078] Additional features and advantages of the present application will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the application. The objectives and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0079] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0080] Figure 1 A schematic diagram of the internal structure of a dry distillation furnace body according to an embodiment of the present application is shown;

[0081] Figure 2 A flow chart of demodulation processing of a received primary side modulated signal according to an embodiment of the present application is shown;

[0082] Figure 3 A flow chart of power transmission and communication cooperation according to an embodiment of the present application is shown;

[0083] Figure 4 A flow chart of a foreign matter detection method according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0084] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0085] The present application provides a metal foreign matter detection device for a high-power SWPIT system, as shown in Figures 1-3As shown, including power transmission adjustable data communication system, energy coupling system and magnetic control switch module, the data communication system includes power level adjustable primary side data transceiver circuit and secondary side data transceiver circuit, one end of the primary side data transceiver circuit and one end of the secondary side data transceiver circuit are connected at both ends of the magnetic control switch module respectively; the energy coupling system includes energy transmitting coil and secondary side power receiving coil, the other end of the primary side data transceiver circuit is connected to the energy transmitting coil, the other end of the secondary side data transceiver circuit is connected to the secondary side power receiving coil, the primary side data transceiver circuit and the secondary side data transceiver circuit both transmit data signal through high frequency carrier, so that the data transmission and power transmission share a coupling link, and the sensitivity of foreign object detection is improved when foreign object appears.

[0086] The primary side data transceiver circuit and the secondary side data transceiver circuit both include signal sending module and signal receiving module, the signal sending module and the signal receiving module on the primary side are connected in parallel to the energy transmitting coil, and the signal sending module and the signal receiving module on the secondary side are connected in parallel to the secondary side power receiving coil, the primary side data transceiver circuit is responsible for modulating the data signal and sending it out through high frequency carrier injection, the secondary side data transceiver circuit receives the modulated signal from the primary side and performs demodulation processing to realize data communication between the primary side and the secondary side, and the primary side data transceiver circuit and the secondary side data transceiver circuit are connected in parallel with the energy transmitting coil and the secondary side power receiving coil to share the coupling link for data transmission.

[0087] When the primary side data transceiver circuit transmits through high frequency carrier injection, the data to be transmitted is modulated and loaded onto the high frequency carrier signal, and then the modulated signal is sent out through the signal sending module on the primary side, and since the signal sending module on the primary side is connected in parallel with the energy transmitting coil, the modulated signal can be coupled with the energy transmitting coil and the secondary side receiving coil for communication.

[0088] The process of modulating the data to be transmitted by the primary side data transceiver circuit is as follows:

[0089] A1, set the baseband signal as m(t) and the high frequency carrier signal as A c cos(w c t), wherein A c is the carrier amplitude before modulation, w c is the carrier angular frequency;

[0090] A2, calculate the modulation index k a according to the high frequency carrier signal, and the calculation formula is as follows:

[0091] Where ΔA is the maximum change of the carrier amplitude.

[0092] A3, the baseband signal m(t) and high frequency carrier signal A c cos(w c t) are superimposed to obtain the modulated signal s(t), and the superimposed formula is as follows:

[0093] s(t)=A c [1+k a m(t)]cos(w c t);

[0094] As Figure 2 shown, the flow of the secondary side data transceiver circuit for demodulating the modulated signal received from the primary side is as follows:

[0095] B11, receiving the modulated signal s(t) from the primary side coupling;

[0096] B12, using a rectifier diode to rectify the received modulated signal s(t) to obtain a rectified signal s r (t), and the rectified signal has the following two cases:

[0097] When s r (t)≥0, s r (t)=s(t);

[0098] When s r (t)<0, s r (t)=0, indicating no signal;

[0099] B13, filtering the rectified signal, and the filtering formula is as follows:

[0100]

[0101] Y(s)=H(s)*s r (t),

[0102] where w c is the carrier angular frequency, Q is the quality factor, s is the complex frequency variable, H(s) is the transfer function of the low-pass filter, s r (t) is the rectified signal, and Y(s) is the filtered signal;

[0103] B14, baseband signal restoration processing is performed on the filtered signal, and the baseband signal restoration formula is as follows:

[0104] M(s)=H(s)*Y(s), where M(s) is the restored baseband signal, H(s) is the transfer function of the low-pass filter, and Y(s) is the filtered signal;

[0105] The primary data transceiver circuit and the secondary data transceiver circuit share a coupling link during data transmission and power transmission, so that they can enter a power transmission and communication coordinated process, and achieve the purpose of adjustable power transmission, such as Figure 3 As shown in the figure, the power transmission and communication coordinated process is as follows:

[0106] B21, without the influence of communication signals, calculate the transmission power P1 without the influence of communication signals, the calculation formula is as follows:

[0107] P1=w1*M1*I1*I2*k1, wherein w1 is the operating angular frequency, M1 is the mutual inductance value, I1 is the primary coil current value, I2 is the secondary coil current value, and k1 is the coupling coefficient, the value range of the coupling coefficient is 0≤k1≤1;

[0108] B22, when the data communication system adopts high-frequency carrier injection main mode to send signals, the communication signal current will be superimposed on the current of the primary coil and the secondary coil, the total current of the primary coil is I 原 =I1+I 1C , wherein I 1C is the primary communication signal current, and I1 is the primary coil current without communication signals; the total current of the secondary coil is I 副 =I2+I 2C , wherein I 2C is the secondary communication signal current, and I2 is the secondary coil current without communication signals;

[0109] B23, according to the total current of the primary coil and the total current of the secondary coil, calculate the new transmission power P2, the calculation formula is as follows:

[0110] P2=w1*M1*I 原 *I 副 *k1, wherein w1 is the operating angular frequency, M1 is the mutual inductance value, I 原 is the total current value of the primary coil, I 副 is the total current value of the secondary coil, and k1 is the coupling coefficient, the value range of the coupling coefficient is 0≤k1≤1;

[0111] B24, according to the transmission power P1 and the new transmission power P2, calculate the primary communication signal voltage amplitude U 原 and the secondary communication signal voltage amplitude U 副 , the calculation formula is as follows:

[0112]

[0113] B25, according to the primary communication signal voltage amplitude U 原 and the secondary communication signal voltage amplitude U 副 , calculate the attenuation amount of the communication signal, the calculation formula is as follows:

[0114]

[0115] B26、According to the calculated attenuation A dB There are two cases for judging the attenuation degree of the communication signal:

[0116] B261、When A dB = 10dB, it is judged that the attenuation of the communication signal is small, and power adjustment is not needed;

[0117] B262、When A dB = 30dB, it is judged that the attenuation of the communication signal is large, and power adjustment is needed;

[0118] The power adjustment mode is as follows: the power adjustment coefficient n is calculated according to the transmission power P1 and the new transmission power P2, and the power adjustment is performed according to the power adjustment coefficient n, and the power adjustment coefficient n is calculated according to the following formula:

[0119]

[0120] When the energy transmitting coil transmits energy, the primary side passes through the energy transmitting coil to pass alternating current, according to the principle of electromagnetic induction, the alternating current will generate an alternating magnetic field around it, and the alternating magnetic field will pass through the secondary side power receiving coil to realize the coupling of the magnetic field, and the calculation formula of the alternating magnetic field strength is:

[0121] B(t) = μ0jil(t), wherein B(t) is the alternating magnetic field strength, μ0 is the vacuum permeability, j is the number of turns per unit length of the coil, and il(t) is the alternating current value passed in;

[0122] When the secondary side power receiving coil receives energy, the secondary side power receiving coil is in the alternating magnetic field generated by the primary side, and according to Faraday's law of electromagnetic induction, an electromotive force will be induced in the secondary side power receiving coil, and then an induced current will be formed in the secondary side power receiving coil, realizing the transmission of energy from the primary side to the secondary side, and in the whole process, the magnetic field environment of energy transmission will be affected by the magnetic field generated by the communication signal current due to the common coupling link of the communication system; wherein the calculation process of the electromotive force induced in the secondary side power receiving coil is as follows:

[0123] 1) First, calculate the magnetic flux φ(t) passing through the secondary side power receiving coil, and the calculation formula is as follows:

[0124] φ(t) = B(t) * S * k1, wherein B(t) is the alternating magnetic field strength, S is the effective cross-sectional area of the secondary side power receiving coil, and k1 is the coupling coefficient;

[0125] 2) Calculate the electromotive force according to the magnetic flux φ(t), and the calculation formula is as follows:

[0126] Wherein, dφ(t) is the small change amount of magnetic flux φ(t), dt is the small change amount of time, N2 is the number of turns of the secondary power receiving coil, e(t) is the electromotive force;

[0127] The energy coupling system further comprises a DC-AC conversion unit for connecting with the DC power supply and converting the input voltage, a compensation network unit, and a load unit, the compensation network unit is connected with the energy transmitting coil and the secondary power receiving coil respectively, the load is connected at one end of the compensation network unit at the secondary side, and the DC-AC conversion unit is connected at one end of the compensation network unit at the primary side, so that the DC power supply is converted into an alternating current source by the DC-AC conversion unit, providing an alternating current source for subsequent energy transmission through the coil; the compensation network unit is used to improve the efficiency and performance of energy transmission, and by adjusting the parameters of the compensation network, the energy can be better coupled and transmitted between the primary and secondary sides, and energy loss is reduced; the load is used to represent the consumption device after the energy is received by the secondary side, and embodies the final use and effect of energy transmission.

[0128] The DC-AC conversion unit converts the DC input voltage into AC output voltage through a DC-AC converter, and loads the AC output voltage on the primary energy transmitting coil, so that an alternating current passes through the primary energy transmitting coil, and an alternating magnetic field is generated, thereby preparing for subsequent energy coupling with the secondary power receiving coil; wherein the DC-AC converter contains an IGBT power switching device and a control circuit, the control circuit drives the IGBT power switching device to be continuously turned on and turned off according to the control strategy of sinusoidal pulse width modulation, so as to convert the DC input into AC output, the voltage of the AC output has a certain frequency (such as frequency f, and the corresponding angular frequency is w=2πf) and amplitude, and the waveform can present different forms according to the adopted modulation mode, such as when SPWM modulation is adopted, the output voltage waveform is approximately sinusoidal.

[0129] The compensation network unit adjusts the resonant characteristics of the circuit by connecting a capacitor C1 in series with the energy transmitting coil and connecting a capacitor C2 in series with the secondary power receiving coil, so as to achieve a better energy coupling effect; the process of adjusting the resonant characteristics by the compensation network unit is as follows:

[0130] C11, calculate the primary resonant frequency when the primary side is connected in series with the compensation capacitor C1 and the inductance value of the primary energy transmitting coil, and the calculation formula is as follows:

[0131] Wherein, w0 is the calculated primary resonant frequency, L1 is the inductance value of the primary energy transmitting coil, and C1 is the capacitance value of the series capacitor C1.

[0132] C12, when the circuit operating frequency is equal to the primary resonant frequency w0, the circuit resonates, at this time the equivalent impedance of the primary circuit is minimum, according to the effective value of the power supply voltage and the equivalent impedance value of the primary, the effective value of the primary current is calculated, the formula of the effective value of the primary current is as follows:

[0133] Wherein, I 1r is the effective value of the primary current, U ac is the effective value of the power supply voltage, R1 is the effective value of the primary equivalent impedance;

[0134] C13, according to the series capacitance C2 of the secondary side and the inductance value of the secondary power receiving coil, the secondary resonant frequency when the secondary side is compensated in series is calculated, and the calculation formula is as follows:

[0135] Wherein, w'0 is the calculated secondary resonant frequency, L2 is the inductance value of the secondary power receiving coil, C2 is the capacitance value of the series capacitance C2;

[0136] C14, when the circuit resonates, the equivalent impedance value of the secondary induced electromotive force in the secondary circuit is minimum, the effective value of the secondary current is calculated according to the secondary induced electromotive force and the equivalent impedance value of the secondary, and the formula of the effective value of the secondary current is as follows:

[0137] Wherein, I 2r is the effective value of the secondary current, e2(t) is the secondary induced electromotive force, R2 is the effective value of the secondary equivalent impedance.

[0138] The load is the induced current I 2r generated by the secondary power receiving coil, through the connected load RL, a voltage drop u L (t) will be generated on the load, the calculation formula of the voltage drop u L (t) is u L (t) = I 2r * RL, and the power consumed by the load PL is calculated according to the calculated voltage drop u L (t), and the calculation formula of the power PL is:

[0139] The calculated power PL is the energy transmitted from the primary through the energy coupling system and actually utilized by the load, which reflects the final effect of energy transmission and completes the complete process of energy transmission from the DC power supply to the load consumption;

[0140] The magnetic control switch module comprises a detection trigger unit for foreign matter detection and a control response unit for on-off control, and the flow of foreign matter detection of the detection trigger unit is as follows:

[0141] D11, when the system is running normally, there is a stable magnetic field distribution between the primary side and the secondary side, the initial magnetic field strength at the position of the magnetic control switch is set as B0(t), and the magnetic field strength threshold B of the magnetic control switch is set th ;

[0142] D12, when there is a foreign object, the foreign object will interfere with the magnetic field, so that the magnetic field strength at the position of the magnetic control switch becomes B(t), and the change amount ΔB(t) of the magnetic field strength is calculated, and the calculation formula is as follows: ΔB(t) = B(t) - B0(t);

[0143] D13, according to the comparison of the calculated magnetic field strength change amount ΔB(t) and the magnetic field strength threshold B th , there are the following two cases:

[0144] D131, when the magnetic field change amount satisfies |ΔB(t)|≥B th , the magnetic control switch will be triggered to change the state, that is, the magnetic control switch changes from the normal initial state to another state, such as the initial state is the open state, and the state after the change is the non-closed state;

[0145] D132, when the magnetic field change amount satisfies |ΔB(t)|<B th , the magnetic control switch will not be triggered to change the state, that is, the magnetic control switch remains in the normal initial state;

[0146] The flow of the control response unit for on-off control is as follows:

[0147] D21, the magnetic control switch will send an electrical signal u out (t) to the control response unit after the state is changed;

[0148] D22, after the control response unit receives the electrical signal u out (t) from the magnetic control switch, it processes according to the preset logic, if the power transmission parameter needs to be adjusted, it is adjusted by adjusting the control voltage input to the energy emitting coil, by changing the size or waveform of the control voltage, the primary side current can be changed, and then the power transmission situation is affected to cope with the influence of the foreign object, such as: if the primary side current needs to be increased, the control voltage is correspondingly increased; by detecting the magnetic control switch module composed of the trigger unit and the control response unit, the system can adjust the power transmission when the foreign object appears, and guarantee the normal operation of the whole system.

[0149] Through cooperation of the data communication system, the energy coupling system and the magnetic control switch module, the data communication system transmits data signals through high-frequency carrier waves, and the data transmission and the power transmission share a coupling link, so that the foreign matter can affect the data transmission and the power transmission when the foreign matter appears, the existence of the foreign matter can be sensed more sensitively, the interference on the foreign matter detection signal is reduced, and the accuracy of the foreign matter detection is improved.

[0150] Based on the above-described metal foreign matter detection device of the high-power SWPIT system, the application further provides a metal foreign matter detection method of a high-power SWPIT system, as shown in the figure, comprising the following steps: Figure 4

[0151] S1, turn off the magnetic control switch, and close the system pipe;

[0152] S2, check whether the secondary side is connected, if not, return to S1, if yes, go to S3;

[0153] S3, turn off the primary side magnetic control switch;

[0154] S4, the primary side data transmission circuit transmits fixed data codes in different power levels in multiple rounds;

[0155] S5, the secondary side data transceiver circuit receives data signals of different power levels, and judges whether the secondary side receiving circuit can correctly decode the data signals of different power levels:

[0156] If not, it is determined that there is a foreign matter, and the system alarms;

[0157] If yes, go to S6;

[0158] S6, after the secondary side correctly decodes, sends a handshake signal to the primary side, and the primary side judges whether the handshake signal is received:

[0159] If not, it is determined that there is a foreign matter, and the system alarms;

[0160] If yes, start power transmission, and go to S7;

[0161] S7, after the power transmission starts, the secondary side data transceiver circuit sends data signals of different power levels at regular intervals, and judges whether there is a handshake signal returned:

[0162] If not, it is determined that there is a foreign matter, the system alarms and turns off the power transmission;

[0163] If yes, keep the power transmission, and continue to detect at regular intervals, to monitor in real time whether there is a foreign matter suddenly entering to affect the power transmission during the charging process.

[0164] ​The principle of foreign matter detection by the above method is: when the secondary side load needs to be charged, the secondary side is placed in the range of the energy transmitting coil, at this time the magnetic control switch works, the primary side magnetic control switch is turned on, the primary side magnetic control switch controls the operation of the data communication system, at this time the primary side signal sending module transmits the fixed data code using different transmission power levels, and performs multiple rounds of data transmission with different power levels, the secondary side signal receiving module receives data information and judges whether the data code with different power levels can be normally decoded, if all data codes can be normally decoded, it is determined that there is no foreign matter affecting power transmission in the power transmission system link at this time, at this time the secondary side signal sending module transmits the handshake signal to the primary side, the primary side decodes the handshake signal and then starts the power transmission part, in order to judge whether foreign matter will suddenly enter during the system charging process, the fixed code data transmission will be transmitted and handshake at regular intervals, when foreign matter affecting power transmission suddenly enters during charging, data transmission will also fail, at this time the system will turn off the power transmission to ensure system safety.

[0165] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A metal foreign object detection device for a high-power SWPIT system, characterized in that: include: A power-adjustable data communication system, the data communication system including a primary-side data transceiver circuit and a secondary-side data transceiver circuit with adjustable power levels, the primary-side data transceiver circuit and the secondary-side data transceiver circuit each including a signal transmitting module and a signal receiving module; An energy coupling system, the energy coupling system comprising an energy transmitting coil and a secondary power receiving coil; A magnetically controlled switch module, comprising a detection trigger unit for foreign object detection and a control response unit for on / off control; One end of the primary-side data transceiver circuit and one end of the secondary-side data transceiver circuit are respectively connected to the two ends of the magnetic control switch module. The other end of the primary-side data transceiver circuit is connected to the energy transmitting coil, and the other end of the secondary-side data transceiver circuit is connected to the secondary-side power receiving coil. Both the primary-side data transceiver circuit and the secondary-side data transceiver circuit transmit data signals via high-frequency carrier waves, so that data transmission and power transmission share a single coupling link, ensuring that foreign objects do not affect data transmission and power transmission when they are present. The modulation process of the primary-side data transceiver circuit for the data to be transmitted is as follows: A1. Set the baseband signal to m(t) and the high-frequency carrier signal to A. c cos(w c t), where A c w represents the carrier amplitude when unmodulated. c The carrier angular frequency; A2. Calculate the modulation index k based on the high-frequency carrier signal. a The calculation formula is as follows: Where ΔA is the maximum change in carrier amplitude; A3. Combine the baseband signal m(t) and the high-frequency carrier signal A c cos(w c The modulated signal s(t) is obtained by superimposing the modulated signals t and t, and the superposition formula is as follows: s(t)=A c [1+k a m(t)]cos(w c t)。 2. The metal foreign object detection device of the high-power SWPIT system according to claim 1, characterized in that: The signal transmitting module and signal receiving module located on the primary side are connected in parallel to the energy transmitting coil, and the signal transmitting module and signal receiving module located on the secondary side are connected in parallel to the secondary power receiving coil. The primary side data transceiver circuit is responsible for modulating the data signal and transmitting it out through high-frequency carrier injection. The secondary side data transceiver circuit receives the modulated signal from the primary side and performs demodulation processing to realize data communication between the primary and secondary sides. The primary side data transceiver circuit and the secondary side data transceiver circuit are connected in parallel with the energy transmitting coil and the secondary power receiving coil, so that they share a coupling link for data transmission.

3. The metal foreign object detection device of a high-power SWPIT system according to claim 2, characterized in that: The demodulation process of the secondary-side data transceiver circuit for receiving the modulated signal from the primary side is as follows: B11. Receive the modulated signal s(t) coupled from the primary side; B12. Use a rectifier diode to rectify the received modulated signal s(t) to obtain the rectified signal s. r (t), the rectified signal has the following two cases: When s r When (t)≥0, s r (t) = s(t); When s r When (t) < 0, s r (t) = 0, indicating no signal; B13. The rectified signal is filtered using the following formula: Y(s)=H(s)*s r (t), Among them, w c Let be the carrier angular frequency, Q be the quality factor, s be the complex frequency variable, and H(s) be the transfer function of the low-pass filter. r Y(t) is the rectified signal, and Y(s) is the filtered signal. B14. Perform baseband signal restoration processing on the filtered signal. The formula for baseband signal restoration is as follows: M(s) = H(s) * Y(s), where M(s) is the restored baseband signal, H(s) is the transfer function of the low-pass filter, and Y(s) is the filtered signal.

4. The metal foreign object detection device of the high-power SWPIT system according to claim 3, characterized in that: The primary-side data transceiver circuit and the secondary-side data transceiver circuit share a coupling link during data transmission and power transmission, enabling them to enter the power transmission and communication coordination process. The power transmission and communication coordination process is as follows: B21. Calculate the transmission power P1 without the influence of communication signals. The calculation formula is as follows: P1 = w1 * M1 * I1 * I2 * k1, where w1 is the operating angular frequency, M1 is the mutual inductance value, I1 is the primary coil current value, I2 is the secondary coil current value, and k1 is the coupling coefficient, with the value of the coupling coefficient ranging from 0 to 1. B22. When a data communication system uses a high-frequency carrier injection method to transmit signals, the communication signal current will be superimposed on the currents of the primary and secondary coils. The total current of the primary coil is I. 原 =I1+I 1C , among which, I 1C I0 is the primary-side communication signal current, and I1 is the primary-side current without a communication signal coil; the total current of the secondary-side coil is I0. 副 =I2+I 2C , among which, I 2C I0 is the secondary communication signal current, and I2 is the secondary non-communication signal coil current. B23. Calculate the new transmission power P2 based on the total current of the primary coil and the total current of the secondary coil. The calculation formula is as follows: P2=w1*M1*I 原 *I 副 *k1, where w1 is the operating angular frequency, M1 is the mutual inductance value, and I 原 I is the total current value of the primary coil. 副 is the total current value of the secondary coil, and k1 is the coupling coefficient, which has a range of 0 ≤ k1 ≤ 1; B24. Calculate the primary-side communication signal voltage amplitude U based on the transmission power P1 and the new transmission power P2. 原 and secondary side communication signal voltage amplitude U 副 The calculation formula is as follows: B25. Based on the voltage amplitude U of the primary-side communication signal. 原 and secondary side communication signal voltage amplitude U 副 The formula for calculating the attenuation of communication signals is as follows: B26. Based on the calculated attenuation A dB To determine the degree of attenuation of a communication signal, there are two possibilities: B261, when A dB When the value is 10dB, it is determined that the communication signal attenuation is small and no power adjustment is required. B262, When A dB When the signal strength is 30dB, it is determined that the communication signal attenuation is large and power adjustment is required. The power adjustment method is as follows: Calculate the power adjustment coefficient n based on the transmitted power P1 and the new transmitted power P2, and then adjust the power according to the power adjustment coefficient n. The formula for calculating the power adjustment coefficient n is as follows:

5. The metal foreign object detection device of a high-power SWPIT system according to claim 4, characterized in that: The energy coupling system further includes a DC-AC conversion unit for connecting to a DC power supply and performing DC-AC conversion on the input voltage, a compensation network unit, and a load unit. The compensation network unit is connected to the energy transmitting coil and the secondary power receiving coil, respectively. The load is connected to one end of the compensation network unit located on the secondary side, and the DC-AC conversion unit is connected to one end of the compensation network unit located on the primary side. The DC-AC conversion unit converts the DC power supply into an AC signal. The compensation network unit is used to improve the efficiency and performance of energy transmission. The load represents the energy consumption device after the secondary side receives the energy.

6. The metal foreign object detection device of a high-power SWPIT system according to claim 5, characterized in that: The compensation network unit adjusts the circuit's resonance characteristics by connecting a capacitor C1 in series with the energy transmitting coil and a capacitor C2 in series with the secondary power receiving coil, thereby achieving better energy coupling. The process for adjusting the resonance characteristics of the compensation network unit is as follows: C11. Calculate the primary resonant frequency when primary-side series compensation is applied, based on the capacitor C1 connected in series on the primary side and the inductance of the primary-side energy-emitting coil. The calculation formula is as follows: Where w0 is the calculated primary resonant frequency, L1 is the inductance of the primary energy emission coil, and C1 is the capacitance of the series capacitor C1. C12. When the circuit's operating frequency equals the primary resonant frequency w0, the circuit resonates. At this time, the equivalent impedance of the primary circuit is at its minimum. The effective value of the primary current at resonance can be calculated based on the effective value of the power supply voltage and the effective value of the primary equivalent impedance. The formula for calculating the effective value of the primary current is as follows: Among them, I 1r U is the effective value of the primary current. ac R1 is the effective value of the power supply voltage, and R1 is the effective value of the primary equivalent impedance. C13. Calculate the secondary resonant frequency under secondary-side series compensation based on the capacitor C2 connected in series on the secondary side and the inductance value of the secondary-side power receiving coil. The calculation formula is as follows: Where w'0 is the calculated secondary resonant frequency, L2 is the inductance of the secondary power receiving coil, and C2 is the capacitance of the series capacitor C2. C14. When the circuit resonates, the equivalent impedance generated by the induced electromotive force on the secondary side is at its minimum. The effective value of the secondary current is calculated based on the induced electromotive force and the equivalent impedance on the secondary side. The formula for calculating the effective value of the secondary current is as follows: Among them, I 2r R2 is the effective value of the secondary current, e2(t) is the induced electromotive force on the secondary side, and R2 is the effective value of the equivalent impedance on the secondary side.

7. A metal foreign object detection device for a high-power SWPIT system according to claim 6, characterized in that: The foreign object detection process of the detection trigger unit is as follows: D11. When the system is running normally, there is a stable magnetic field distribution between the primary and secondary sides. Set the initial magnetic field strength at the location of the magnetic switch to B0(t) and set the magnetic field strength threshold B of the magnetic switch. th ; D12. When a foreign object appears, it will interfere with the magnetic field, causing the magnetic field strength at the magnetic switch position to become B(t). Calculate the change in magnetic field strength ΔB(t). The calculation formula is as follows: ΔB(t)=B(t)-B0(t). D13. Based on the calculated change in magnetic field strength ΔB(t) and the magnetic field strength threshold B th The comparison revealed the following two scenarios: D131. When the change in magnetic field satisfies |ΔB(t)|≥B th When the magnetic switch is triggered, it will change its state, that is, the magnetic switch will change from its normal initial state to another state. D132. When the change in magnetic field satisfies |ΔB(t)|<B th When the magnetic switch is activated, it will not be triggered to change its state; that is, the magnetic switch will remain in its normal initial state.

8. A metal foreign object detection device for a high-power SWPIT system according to claim 7, characterized in that: The control response unit performs on / off control as follows: D21. After the magnetic switch changes state, it will send an electrical signal u to the control response unit. out (t); D22. The control response unit receives an electrical signal u from the magnetic switch. out After (t), the judgment and processing are carried out according to the preset logic. If the power transmission parameters need to be adjusted, the control voltage input to the energy transmission coil is adjusted. By changing the magnitude or waveform of the control voltage, the primary current can be changed, thereby affecting the power transmission.

9. A method for detecting metallic foreign objects in a high-power SWPIT system, based on a metallic foreign object detection device for a high-power SWPIT system according to any one of claims 1-8, characterized in that: Includes the following steps: S1. Disconnect the magnetic switch and shut down the system. S2. Check if the secondary edge is connected. If the secondary edge is not connected, return to S1; if the secondary edge is connected, proceed to S3. S3, Primary side magnetic control switch closed; S4. The primary-side data transmission circuit transmits fixed data codes in multiple rounds at different power levels. S5. The secondary-side data transceiver circuit receives data signals of different power levels and determines whether the secondary-side receiving circuit can correctly decode the data signals of each power level: If the system cannot decode correctly and determines that a foreign object is present, an alarm will be triggered. If the decoding is successful, proceed to S6; S6. After the secondary edge can correctly decode, it sends a handshake signal to the primary edge. The primary edge then determines whether it has received the handshake signal. If no foreign object is received, the system will detect the presence of a foreign object and trigger an alarm. If received, power transmission begins, proceeding to S7; S7. After power transmission begins, the secondary-side data transceiver circuit periodically sends data signals of different power levels to determine if a handshake signal has been returned. If no handshake signal is returned, it is determined that there is a foreign object, the system alarms and shuts down power transmission; If a handshake signal is returned, maintain power transmission and continue periodic checks to monitor in real time whether any foreign objects suddenly enter during the charging process and affect power transmission.

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