Closed-loop control method and device for single-transmitting-side analog circuit of wireless power transmission system

Abstract

The invention discloses a closed-loop control method and device for a single transmitting side analog circuit of a wireless power transmission system, and the method comprises the steps: constructing a power transmission structure of the wireless power transmission system based on an SS-type two-coil wireless power transmission topology and an E-type power amplifier, and carrying out the power transmission; obtaining a voltage signal and a current signal by using a signal detection circuit; inputting the signal into a receiving side information back calculation circuit to obtain a coupling coefficient of a primary side coil and a secondary side coil and the size of a load; the duty ratio when the power transmission structure of the wireless power transmission system has the optimal transmission efficiency and output power is obtained through the transmitting side switching tube control structure, control square waves of the E-type power amplifier switching tube are generated according to the duty ratio, the control square waves are sent into the switching tube driving circuit, the control square waves are amplified, and the power transmission efficiency of the E-type power amplifier switching tube is improved. And opening and closing of the switch tube are controlled to complete closed-loop control. The device is simple in structure, high in efficiency, low in cost and wide in application range, and has good practical application value.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical equipment and electrical engineering construction, and in particular to a closed-loop control method and device for a single-transmitter-side analog circuit of a wireless power transmission system. Background Art

[0002] With the development of 5G and the internet, personal portable electronic products have experienced explosive growth. However, the incompatibility of interfaces between different electronic products has brought inconvenience to charging. At the same time, traditional wired power supply methods are becoming increasingly difficult to meet the needs of productivity development in terms of power supply safety and construction costs. Therefore, people hope to find a WPT (Wireless Power Transfer) method to completely break free from the constraints of traditional wired power supply methods. New technologies are urgently needed to improve the performance of wireless power transmission systems. As a type of WPT, magnetically coupled resonant WPT has attracted much attention in recent research due to its long transmission distance and high efficiency. However, the perturbation of the coil's coupling coefficient and the perturbation of the load's impedance parameters work together to affect the overall transmission characteristics of the system.

[0003] In recent years, research teams in related fields have used Class E power amplifiers as the excitation source for wireless power transmission systems to further improve system efficiency at high frequencies. However, the Class E power amplifier topology is sensitive to impedance variations. The equivalent input impedance of actual power loads varies continuously during the power supply process due to differences in operating conditions or charging strategies, making the design of wireless power transmission systems driven by Class E power amplifiers more difficult. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for closed-loop control of a single transmitter-side analog circuit of a wireless power transmission system, so as to realize closed-loop control of the transmitter side of the wireless power transmission system at high frequencies, so that the system can have stable and high output power and transmission efficiency.

[0005] The present invention adopts the following technical solution: a closed-loop control method for a single transmitter-side analog circuit of a wireless power transmission system, comprising the following steps:

[0006] S1. Based on the SS-type two-coil wireless power transmission topology and the Class E power amplifier, a wireless power transmission system power transmission structure is constructed to perform power transmission.

[0007] S2. Based on the power obtained in step S1, a voltage signal and a current signal are obtained using a signal detection circuit.

[0008] S3. Input the signal obtained in step S2 into the receiving side information inverse calculation circuit to obtain the coupling coefficient of the primary and secondary coils and the size of the load.

[0009] S4. Based on the data obtained in step S3, the duty cycle of the wireless power transmission system power transmission structure when it has optimal transmission efficiency and output power is obtained through the transmitter-side switch tube control structure. According to the duty cycle, a control square wave of the class E power amplifier switch tube is generated. The control square wave is sent to the switch tube drive circuit, the control square wave is amplified, and the switching tube is controlled to be turned on and off to complete closed-loop control.

[0010] Furthermore, in step S1, the output end of the class E power amplifier is connected to the input end of the SS type two-coil wireless power transmission topology to obtain a power transmission structure of the wireless power transmission system.

[0011] Furthermore, in step S2, the signal detection circuit includes a voltage sensor and a current sensor.

[0012] Furthermore, in step S3, the receiving side information inverse calculation circuit includes a bandpass filter, a low-pass filter, a peak detection circuit, an analog multiplier and a parameter information inverse calculator.

[0013] The voltage signal and current signal are input into the information inverse calculation circuit on the receiving side, and are respectively passed through a bandpass filter to extract the fundamental frequency component of the signal waveform. The specific expression is:

[0014] U(t)=U m sin(ω u t+θ u )

[0015] I(t)=I m sin(ω i t+θ i )

[0016] Among them, U(t) represents the voltage fundamental wave at the tth moment, U m Indicates the voltage fundamental amplitude, ω u Indicates the frequency of the voltage fundamental wave, θ u represents the phase of the voltage fundamental wave, I(t) represents the current fundamental wave at the tth moment, I m Indicates the fundamental amplitude of the current, ω i Indicates the frequency of the current fundamental wave, θ i Indicates the phase of the current fundamental wave; ω u =ω i =ω0, ω0 represents the frequency of the square wave controlled by the switch tube.

[0017] The fundamental frequency component of the signal waveform is divided into two paths. One path is multiplied by the first analog multiplier to obtain the first waveform UI(t). The specific expression is:

[0018] UI(t)=0.5U mI m sin(ω u t+θ u +ω i t+θ i )+0.5U m I m sin(ω u t+θ u -(ω i t+θ i )).

[0019] The other path passes through the peak detection circuit to obtain the voltage fundamental amplitude U m and the current fundamental amplitude I m , the two amplitudes are divided into two paths for corresponding processing, one path is multiplied by the second analog multiplier to obtain U m I m The other path passes through the peak compensator, and the compensation coefficient of the amplitude is obtained according to the transfer function of the bandpass filter and the low-pass filter, and the amplitude is compensated to obtain the compensated voltage fundamental amplitude U m ' and the current fundamental amplitude after compensation I m '.

[0020] The first waveform UI(t) is filtered by a low-pass filter to obtain the second waveform UI_1(t). The specific expression is:

[0021] UI_1(t)=0.5U m I m sin((ω u t-ω i t)+(θ u -θ i ))=0.5U m I m sin(θ u -θ i )

[0022] U m I m and UI_1(t) pass through the parameter information inverse calculator to obtain the phase θ of the voltage fundamental wave u and the phase θ of the current fundamental wave i ;According to the transfer function of the bandpass filter and the low-pass filter, the phase compensation coefficient is obtained, and the phase angle compensator is used to compensate the phase to obtain the compensated voltage fundamental phase θ u ' and the current fundamental phase after compensation θ i '.

[0023] Coupling coefficient k between primary and secondary coils 12 and the load resistor R L The calculation formula is:

[0024]

[0025] Wherein, ω represents the operating frequency of the wireless power transmission system; L1 represents the first inductor in the SS-type two-coil wireless power transmission topology; C1 represents the first capacitor in the SS-type two-coil wireless power transmission topology; L2 represents the second inductor in the SS-type two-coil wireless power transmission topology; C2 represents the second capacitor in the SS-type two-coil wireless power transmission topology; L b Represents the residual inductance in a Class E power amplifier.

[0026] Furthermore, in step S4, obtaining the duty cycle includes the following:

[0027] At the parity-time symmetric operating frequency point within the parity-time symmetry region, the SS-type two-coil wireless power transmission topology in the power transmission structure of the wireless power transmission system has the best output power and transmission efficiency. The calculation formula for its operating frequency within the parity-time symmetry region is:

[0028]

[0029] Among them, ω PT represents the operating frequency in the parity-time symmetry region; Γ2=(r2+R L ) / (2L2), r2 represents the internal resistance of the receiving coil.

[0030] Critical coupling coefficient k c The expression is:

[0031]

[0032] When k 12 Greater than k c When ω = ω, it indicates that the wireless power transmission system is located in the parity-time symmetry region. At this time, the operating frequency of the system is ω = ω PT ; When k 12 Less than k c When ω = ω, it indicates that the wireless power transmission system is located in the symmetry breaking region. At this time, the operating frequency of the system is ω = ω n , where ω n Indicates the natural operating frequency of the wireless power transmission system, When k 12 Equal to k c When , it indicates that the wireless power transmission system is in the critical symmetry area.

[0033] The expression of the steady-state equation of the class E power amplifier is:

[0034]

[0035] Where I1 represents the DC supply current; D represents the duty cycle of the switch tube; φ represents the current phase difference between the switch tube and the class E power amplifier load network; V I Indicates the DC supply voltage.

[0036] The zero voltage turn-on condition is introduced into the class E power amplifier, and its constraint formula is:

[0037]

[0038] By combining the steady-state equation of the class E power amplifier and the constraint formula of the zero voltage conduction condition, the duty cycle D of the switch tube is obtained.

[0039] Furthermore, the present invention also proposes a device for a closed-loop control method of a single transmitter-side analog circuit of a wireless power transmission system, comprising:

[0040] Wireless power transmission system power transmission structure, signal detection circuit, receiving side information inversion circuit, transmitting side switch tube control structure and switch tube drive circuit.

[0041] The input end of the signal detection circuit is connected to the transmitting side of the SS-type two-coil wireless power transmission topology in the power transmission structure of the wireless power transmission system, the output end of the signal detection circuit is connected to the input end of the receiving-side information inversion circuit, the output end of the receiving-side information inversion circuit is connected to the input end of the transmitting-side switch tube control structure and is grounded, the output end of the transmitting-side switch tube control structure is connected to the input end of the switch tube drive circuit, and the output end of the switch tube drive circuit is connected to the Class E power amplifier in the power transmission structure of the wireless power transmission system.

[0042] Furthermore, the SS type two-coil wireless power transmission topology includes a first inductor L1, a first capacitor C1, a second inductor L2, a second capacitor C2, a transmitting coil internal resistance r1, a receiving coil internal resistance r2 and a load resistor R L .

[0043] The first capacitor C1, the first inductor L1, and the transmitting coil internal resistance r1 are located on the transmitting side, the second capacitor C2, the load resistor R L , the internal resistance r2 of the receiving coil, and the second inductor L2 are located on the receiving side.

[0044] The class E power amplifier includes a choke inductor L f , switch tube D1, switch tube parallel capacitor C3 and residual inductance L b .

[0045] Choke inductor L f One end is connected to the positive pole of the DC power supply, the negative pole of the DC power supply is grounded, and the choke inductor L f The other end is connected to the drain of the switch tube D1, one end of the switch tube parallel capacitor C3, and the residual inductance Lb The source of the switch tube D1 is connected to the other end of the switch tube parallel capacitor C3, the residual inductance L b to the other end of the

[0046] In the power transmission structure of the wireless power transmission system, the second inductor L2, the second capacitor C2, and the load resistor R L and the internal resistance r2 of the receiving coil are connected in series to form a series circuit; the choke inductor L f One end is connected to the positive pole of the DC power supply, the negative pole of the DC power supply is grounded, and the choke inductor L f The other end is connected to the drain of the switch tube D1, one end of the switch tube parallel capacitor C3, and the residual inductance L b The source of the switch tube D1 is connected to the other end of the switch tube parallel capacitor C3 and one end of the transmitting coil internal resistance r1 respectively. The residual inductance L b The other end of is connected to one end of the first capacitor C1, the other end of the first capacitor C1 is connected to one end of the first inductor L1, the other end of the first inductor L1 is connected to the other end of the transmitting coil internal resistance r1, and the gate of the switch tube D1 is connected to the output end of the switch tube driving circuit.

[0047] Furthermore, the inductance of the first inductor L1 is equal to the inductance of the second inductor L2, and the capacitance of the first capacitor C1 is equal to the capacitance of the second capacitor C2.

[0048] Furthermore, the peak detection circuit includes a diode, a capacitor and a resistor; the positive electrode of the diode is connected to one stage of the bandpass filter output end, the negative electrode of the diode is connected to one end of the capacitor and the resistor, the other end of the capacitor and the resistor is connected, and connected to the other stage of the bandpass filter output end.

[0049] The output end of the signal detection circuit is connected to the input end of the bandpass filter, the output end of the bandpass filter is respectively connected to the input end of the peak detection circuit and the input end of the first analog multiplier, the output end of the first analog multiplier is connected to the input end of the low-pass filter, the output end of the peak detection circuit is connected to the input end of the second analog multiplier, and the output end of the low-pass filter and the output end of the second analog multiplier are both connected to the parameter information inverse calculator.

[0050] Furthermore, the parameter information inverse calculator includes a first resistor R C , the second resistor R c , the first to sixth transistors T1 to T6 and a current source.

[0051] Power supply V CC Respectively with the first resistor R C One end of the second resistor R c One end of the first resistor R CThe other end is connected to the emitter of the first transistor T1, the emitter of the third transistor T3, and the positive electrode of the first voltage u0 respectively; the second resistor R c The other end is connected to the emitter of the second transistor T2, the emitter of the fourth transistor T4, and the negative electrode of the first voltage u0; the second voltage U X The positive electrode is connected to the base of the first transistor T1 and the base of the fourth transistor T4 respectively; the second voltage U X The negative electrode of the transistor is connected to the base of the second transistor T2 and the base of the third transistor T3 respectively; the collector of the first transistor T1 is connected to the collector of the second transistor T2 and the emitter of the fifth transistor T5 respectively; the collector of the third transistor T3 is connected to the collector of the fourth transistor T4 and the emitter of the sixth transistor T6 respectively; the third voltage U Y The positive electrode is connected to the base of the fifth transistor T5, and the third voltage U Y The negative electrode is connected to the base of the sixth transistor T6; the collector of the fifth transistor T5 is connected to the collector of the sixth transistor T6, and is commonly connected to one end of the current source I, and the other end of the current source I is grounded.

[0052] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0053] 1. The present invention adopts an analog circuit implementation method to enable the wireless power transmission system to still collect key waveform information at MHz or even higher frequencies, and to use this information to inversely calculate the parameters of the secondary side of the system.

[0054] 2. The present invention can calculate the Class E power amplifier switch tube control square wave corresponding to the optimal output power and transmission efficiency of the wireless power transmission system based on the system secondary side parameters obtained by inverse calculation. Using this square wave signal as the excitation signal of the switch tube can enable the system to have the optimal output power and transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is an implementation flow chart of the closed-loop control method of the present invention.

[0056] Figure 2 It is a schematic diagram of the receiving side information inverse calculation circuit of the present invention.

[0057] Figure 3 It is a structural diagram of the closed-loop control device of the present invention.

[0058] Figure 4 It is a circuit structure diagram of the parameter information inverse calculator of the present invention.

[0059] Figure 5 4 is a closed-loop control simulation diagram of an embodiment of the present invention.

[0060] Figure 6 4 is a graph showing the relationship between frequency and coupling coefficient according to an embodiment of the present invention.

[0061] Figure 7 4 is a diagram showing a voltage waveform at the switch end of a Class E power amplifier according to an embodiment of the present invention.

[0062] Figure 8 FIG. 4 is a graph showing the relationship between transmission efficiency and output power as the operating frequency changes according to an embodiment of the present invention. DETAILED DESCRIPTION

[0063] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0064] To achieve the above objectives, the present invention proposes a closed-loop control method for a single transmitter-side analog circuit of a wireless power transmission system, such as Figure 1 The specific steps are as follows:

[0065] S1. Connect the output of the class E power amplifier to the input of the SS-type two-coil wireless power transmission topology to build a wireless power transmission system power transmission structure for power transmission.

[0066] S2. Based on the power obtained in step S1, a voltage signal and a current signal are obtained using a signal detection circuit. The signal detection circuit includes a voltage sensor and a current sensor.

[0067] S3: Input the signal obtained in step S2 into the receiving side information inverse calculation circuit to obtain the coupling coefficient of the primary and secondary coils and the size of the load.

[0068] like Figure 2 As shown, the receiving side information inverse calculation circuit includes BPF (Band Pass Filter, band pass filter), LPF (Low Pass Filter, low pass filter), PK (Peak, peak detection circuit), analog multiplier and parameter information inverse calculator.

[0069] The voltage signal and current signal are input into the information inverse calculation circuit on the receiving side, and are respectively passed through a bandpass filter to extract the fundamental frequency component of the signal waveform. The specific expression is:

[0070] U(t)=U m sin(ω u t+θ u )

[0071] I(t)=I m sin(ω i t+θ i )

[0072] Among them, U(t) represents the voltage fundamental wave at the tth moment, U m Indicates the voltage fundamental amplitude, ω u Indicates the frequency of the voltage fundamental wave, θ u represents the phase of the voltage fundamental wave, I(t) represents the current fundamental wave at the tth moment, I m Indicates the fundamental amplitude of the current, ω i Indicates the frequency of the current fundamental wave, θ i Indicates the phase of the current fundamental wave; ω u =ω i =ω0, ω0 represents the frequency of the square wave controlled by the switch tube.

[0073] The fundamental frequency component of the signal waveform is divided into two paths. One path is multiplied by the first analog multiplier to obtain the first waveform UI(t). The specific expression is:

[0074] UI(t)=0.5U m I m sin(ω u t+θ u +ω i t+θ i )+0.5U m I m sin(ω u t+θ u -(ω i t+θ i )).

[0075] The other path passes through the peak detection circuit to obtain the voltage fundamental amplitude U m and the current fundamental amplitude I m , the two amplitudes are divided into two paths for corresponding processing, one path is multiplied by the second analog multiplier to obtain U m I m Since the voltage and current waveforms have passed through the bandpass filter and the low-pass filter, the amplitude and phase information obtained are deviated. Then the other path passes through the AC (Amplitude Compensation, peak compensator), and the amplitude compensation coefficient is obtained according to the transfer function of the bandpass filter and the low-pass filter. The amplitude is compensated to obtain the compensated voltage fundamental amplitude U m ' and the current fundamental amplitude after compensation I m '.

[0076] The first waveform UI(t) is filtered by a low-pass filter, where the waveform output by the analog multiplier contains ω u -ω i 、ω u +ω iThe two operating frequency points are filtered by a low-pass filter, and the high-frequency components are filtered out to obtain the second waveform UI_1(t). The specific expression is:

[0077] UI_1(t)=0.5U m I m sin((ω u t-ω i t)+(θ u -θ i ))=0.5U m I m sin(θ u -θ i ).

[0078] U m I m and UI_1(t) pass through the parameter information inverse calculator to obtain the phase θ of the voltage fundamental wave u and the phase θ of the current fundamental wave i The phase compensation coefficient is obtained according to the transfer function of the bandpass filter and the low-pass filter, and the phase is compensated using PAC (Phase Angle Compensation) to obtain the compensated voltage fundamental phase θ u ' and the current fundamental phase after compensation θ i '.

[0079] Coupling coefficient k between primary and secondary coils 12 and the load resistor R L The calculation formula is:

[0080]

[0081] Wherein, ω represents the operating frequency of the wireless power transmission system, which is equal to the driving frequency of the switch tube in the Class E power amplifier; L1 represents the first inductor in the SS-type two-coil wireless power transmission topology; C1 represents the first capacitor in the SS-type two-coil wireless power transmission topology; L2 represents the second inductor in the SS-type two-coil wireless power transmission topology; C2 represents the second capacitor in the SS-type two-coil wireless power transmission topology; L b Represents the residual inductance in a Class E power amplifier.

[0082] The center frequency of the bandpass filter needs to be close to the operating frequency of the class E power amplifier switch tube. In addition, this part can also be implemented by any active or passive circuit with bandpass filtering function; the cutoff frequency of the low-pass filter needs to be set to ω uIn addition, this part can also be implemented by any active or passive circuit with low-pass filtering function; the peak detection circuit can use a peak detection circuit built by an active circuit to implement this function; since the voltage and current waveforms are positive and negative, the analog multiplier needs to be able to work in four quadrants, which can be implemented by a four-quadrant variable transconductance analog multiplier circuit.

[0083] S4. Based on the data obtained in step S3, the duty cycle of the wireless power transmission system power transmission structure when it has optimal transmission efficiency and output power is obtained through the transmitter-side switch tube control structure. According to the duty cycle, a control square wave of the class E power amplifier switch tube is generated. The control square wave is sent to the switch tube drive circuit, the control square wave is amplified, sufficient drive power is provided, and the switch tube is controlled to be turned on and off to complete closed-loop control.

[0084] Among them, obtaining the duty cycle includes the following:

[0085] At the parity-time symmetric operating frequency point within the parity-time symmetry region, the SS-type two-coil wireless power transmission topology in the power transmission structure of the wireless power transmission system has the best output power and transmission efficiency. The calculation formula for its operating frequency within the parity-time symmetry region is:

[0086]

[0087] Among them, ω PT represents the operating frequency in the parity-time symmetry region; Γ2=(r2+R L ) / (2L2), r2 represents the internal resistance of the receiving coil.

[0088] In order to increase the actual running speed of the program, the frequency f and duty cycle D of the switch tube control square wave need to be pre-calculated and stored in advance. 12 Scan from 0 to 1, with a point interval of 0.001, and the variable R L Scan from 5Ω to 20Ω, with a point interval of 0.01. The specific scanning range can be determined according to the actual application system.

[0089] Critical coupling coefficient k c The expression is:

[0090]

[0091] When k 12 Greater than k c When ω = ω, it indicates that the wireless power transmission system is located in the parity-time symmetry region. At this time, the operating frequency of the system is ω = ω PT ; When k 12 Less than k cWhen ω = ω, it indicates that the wireless power transmission system is located in the symmetry breaking region. At this time, the operating frequency of the system is ω = ω n , where ω n Indicates the natural operating frequency of the wireless power transmission system, When k 12 Equal to k c When , it indicates that the wireless power transmission system is in the critical symmetry area.

[0092] The expression of the steady-state equation of the class E power amplifier is:

[0093]

[0094]

[0095] Where I1 represents the DC supply current; D represents the duty cycle of the switch tube; φ represents the current phase difference between the switch tube and the class E power amplifier load network; V I Indicates the DC supply voltage.

[0096] In order to ensure that the Class E power amplifier has low switching loss at high frequencies, it is also necessary to introduce the zero voltage turn-on condition. The constraint formula is:

[0097]

[0098] By combining the steady-state equation of the class E power amplifier and the constraint formula of the zero voltage conduction condition, the duty cycle D of the switch tube is obtained.

[0099] The present invention proposes a device for closed-loop control of a single transmitter-side analog circuit of a wireless power transmission system, such as Figure 3 Shown, including:

[0100] Wireless power transmission system power transmission structure, signal detection circuit, receiving side information inversion circuit, transmitting side switch tube control structure and switch tube drive circuit.

[0101] The input end of the signal detection circuit is connected to the transmitting side of the SS-type two-coil wireless power transmission topology in the power transmission structure of the wireless power transmission system, the output end of the signal detection circuit is connected to the input end of the receiving-side information inversion circuit, the output end of the receiving-side information inversion circuit is connected to the input end of the transmitting-side switch tube control structure and is grounded, the output end of the transmitting-side switch tube control structure is connected to the input end of the switch tube drive circuit, and the output end of the switch tube drive circuit is connected to the Class E power amplifier in the power transmission structure of the wireless power transmission system.

[0102] The SS type two-coil wireless power transmission topology includes the first inductor L1, the first capacitor C1, the second inductor L2, the second capacitor C2, the transmitting coil internal resistance r1, the receiving coil internal resistance r2 and the load resistor R L .

[0103] The first capacitor C1, the first inductor L1, and the transmitting coil internal resistance r1 are located on the transmitting side, the second capacitor C2, the load resistor R L , the internal resistance r2 of the receiving coil, and the second inductor L2 are located on the receiving side.

[0104] The class E power amplifier includes a choke inductor L f , switch tube D1, switch tube parallel capacitor C3 and residual inductance L b .

[0105] Choke inductor L f One end is connected to the positive pole of the DC power supply, the negative pole of the DC power supply is grounded, and the choke inductor L f The other end is connected to the drain of the switch tube D1, one end of the switch tube parallel capacitor C3, and the residual inductance L b The source of the switch tube D1 is connected to the other end of the switch tube parallel capacitor C3 and the residual inductance L b to the other end of the

[0106] In the power transmission structure of the wireless power transmission system, the second inductor L2, the second capacitor C2, and the load resistor R L and the internal resistance r2 of the receiving coil are connected in series to form a series circuit; the choke inductor L f One end is connected to the positive pole of the DC power supply, the negative pole of the DC power supply is grounded, and the choke inductor L f The other end is connected to the drain of the switch tube D1, one end of the switch tube parallel capacitor C3, and the residual inductance L b The source of the switch tube D1 is connected to the other end of the switch tube parallel capacitor C3 and one end of the transmitting coil internal resistance r1 respectively. The residual inductance L b The other end of is connected to one end of the first capacitor C1, the other end of the first capacitor C1 is connected to one end of the first inductor L1, the other end of the first inductor L1 is connected to the other end of the transmitting coil internal resistance r1, and the gate of the switch tube D1 is connected to the output end of the switch tube driving circuit.

[0107] The inductance of the first inductor L1 is equal to the inductance of the second inductor L2 , and the capacitance of the first capacitor C1 is equal to the capacitance of the second capacitor C2 .

[0108] The peak detection circuit includes a diode, a capacitor and a resistor; the positive electrode of the diode is connected to the first stage of the bandpass filter output end, the negative electrode of the diode is connected to one end of the capacitor and the resistor, the other end of the capacitor and the resistor is connected and connected to the other stage of the bandpass filter output end.

[0109] The output end of the signal detection circuit is connected to the input end of the bandpass filter, the output end of the bandpass filter is respectively connected to the input end of the peak detection circuit and the input end of the first analog multiplier, the output end of the first analog multiplier is connected to the input end of the low-pass filter, the output end of the peak detection circuit is connected to the input end of the second analog multiplier, and the output end of the low-pass filter and the output end of the second analog multiplier are both connected to the parameter information inverse calculator.

[0110] like Figure 4 As shown, the parameter information inverse calculator includes a first resistor R C , the second resistor R c , the first to sixth transistors T1 to T6 and a current source.

[0111] Power supply V CC Respectively with the first resistor R C One end of the second resistor R c One end of the first resistor R C The other end is connected to the emitter of the first transistor T1, the emitter of the third transistor T3, and the positive electrode of the first voltage u0 respectively; the second resistor R c The other end is connected to the emitter of the second transistor T2, the emitter of the fourth transistor T4, and the negative electrode of the first voltage u0; the second voltage U X The positive electrode is connected to the base of the first transistor T1 and the base of the fourth transistor T4 respectively; the second voltage U X The negative electrode of the transistor is connected to the base of the second transistor T2 and the base of the third transistor T3 respectively; the collector of the first transistor T1 is connected to the collector of the second transistor T2 and the emitter of the fifth transistor T5 respectively; the collector of the third transistor T3 is connected to the collector of the fourth transistor T4 and the emitter of the sixth transistor T6 respectively; the third voltage U Y The positive electrode is connected to the base of the fifth transistor T5, and the third voltage U Y The negative electrode is connected to the base of the sixth transistor T6; the collector of the fifth transistor T5 is connected to the collector of the sixth transistor T6, and is commonly connected to one end of the current source I, and the other end of the current source I is grounded.

[0112] The inductors and capacitors on the transmitting side and the receiving side may be composed of components with lumped parameters or components with distributed parasitic parameters.

[0113] The class E power amplifier is an FPGA or a digital logic processing chip.

[0114] Example:

[0115] The closed-loop control simulation diagram obtained using power simulation software is as follows Figure 5As shown in the figure, the main circuit is an SS type two-coil wireless power transmission topology. On this basis, the transmitter side analog closed-loop control circuit is embedded. The U and I of the transmitter side circuit are used as input quantities, and the peak value detection circuit outputs the voltage and current peak value U m _out、I m _out, the above is combined with the output result of the analog multiplier to obtain the voltage waveform phase fai_out. m _out、I m _out and fai_out are used as output quantities to calculate the Class E power amplifier switch tube control square wave that can make the system have the best transmission efficiency and output power, and output it to the transmitting side to form an overall closed-loop control. Figure 6 、 Figure 7 As shown, Figure 6 The relationship between the simulation frequency of the wireless power transmission system and the theoretical calculation frequency and the coupling coefficient is obtained from Figure 6 It can be seen that the simulation values ​​are basically consistent with the theoretical calculation values, that is, the designed closed-loop control method can enable the wireless power transmission system to operate at the expected operating frequency.

[0116] Figure 7 (a) is the voltage waveform of the switch tube end of the Class E power amplifier in the wireless power transmission system at a point in the symmetrical region. It can be seen from the figure that the voltage of the switch tube end can achieve better zero voltage derivative conduction in these two regions, reducing the switching loss of the switch tube at high frequency. Figure 7 (b) is the voltage waveform of the switch tube end of the Class E power amplifier in the damaged area of ​​the wireless power transmission system. It can be seen from the figure that the voltage at the switch tube end also achieves a good zero voltage derivative conduction, reducing the switching loss of the switch tube at high frequencies. Figure 8 (a) and Figure 8 As shown in (c), in the symmetric region, the output power of the wireless power transmission system at the operating frequency is the maximum output power under the coupling coefficient, and the theoretical transmission efficiency is also close to 1; Figure 8 (b) and Figure 8 As shown in (d), in the symmetrically damaged region, the output power of the wireless power transmission system at the operating frequency is low under the coupling coefficient, and the transmission efficiency is still lower than 30% at the highest.

[0117] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A closed-loop control method for a single transmitter-side analog circuit of a wireless power transmission system, characterized in that: include: S1. Based on the SS-type two-coil wireless power transmission topology and the Class E power amplifier, a wireless power transmission system power transmission structure is constructed to perform power transmission. S2. Based on the power obtained in step S1, a voltage signal and a current signal are obtained using a signal detection circuit; S3, inputting the signal obtained in step S2 into the receiving side information inverse calculation circuit to obtain the coupling coefficient of the primary and secondary coils and the size of the load; S4. Based on the data obtained in step S3, the duty cycle of the wireless power transmission system power transmission structure when it has optimal transmission efficiency and output power is obtained through the transmitter-side switch tube control structure. According to the duty cycle, a control square wave of the class E power amplifier switch tube is generated. The control square wave is sent to the switch tube drive circuit, the control square wave is amplified, and the switching tube is controlled to be turned on and off to complete closed-loop control.

2. The closed-loop control method for a single transmitter-side analog circuit of a wireless power transmission system according to claim 1, characterized in that: In step S1, the output end of the class E power amplifier is connected to the input end of the SS type two-coil wireless power transmission topology to obtain a power transmission structure of the wireless power transmission system.

3. The closed-loop control method for a single transmitter-side analog circuit of a wireless power transmission system according to claim 1, characterized in that: In step S2, the signal detection circuit includes a voltage sensor and a current sensor.

4. The closed-loop control method for a single transmitter-side analog circuit of a wireless power transmission system according to claim 1, wherein: In step S3, the receiving side information inverse calculation circuit includes a bandpass filter, a low-pass filter, a peak detection circuit, an analog multiplier and a parameter information inverse calculator; The voltage signal and current signal are input into the information inverse calculation circuit on the receiving side, and are respectively passed through a bandpass filter to extract the fundamental frequency component of the signal waveform. The specific expression is: U(t)=U m sin(ω u t+θ u ) I(t)=I m sin(ω i t+θ i ) Among them, U(t) represents the voltage fundamental wave at the tth moment, U m Indicates the voltage fundamental amplitude, ω u Indicates the frequency of the voltage fundamental wave, θ u represents the phase of the voltage fundamental wave, I(t) represents the current fundamental wave at the tth moment, I m Indicates the fundamental amplitude of the current, ω i Indicates the frequency of the current fundamental wave, θ i Indicates the phase of the current fundamental wave; ω u =ω i =ω0, ω0 represents the frequency of the square wave controlled by the switch tube; The fundamental frequency component of the signal waveform is divided into two paths. One path is multiplied by the first analog multiplier to obtain the first waveform UI(t). The specific expression is: UI(t)=0.5U m I m sin(ω u t+θ u +oh i t+θ i )+0.5U m I m sin(ω u t+θ u -(oh i t+θ i )); The other path passes through the peak detection circuit to obtain the voltage fundamental amplitude U m and the current fundamental amplitude I m , the two amplitudes are divided into two paths for corresponding processing, one path is multiplied by the second analog multiplier to obtain U m I m The other path passes through the peak compensator, and the compensation coefficient of the amplitude is obtained according to the transfer function of the bandpass filter and the low-pass filter, and the amplitude is compensated to obtain the compensated voltage fundamental amplitude U m ' and the current fundamental amplitude after compensation I m '; The first waveform UI(t) is filtered by a low-pass filter to obtain the second waveform UI_1(t). The specific expression is: UI_1(t)=0.5U m I m sin((ω u t-w i t)+(θ u -θ i )); U m I m and UI_1(t) pass through the parameter information inverse calculator to obtain the phase θ of the voltage fundamental wave u and the phase θ of the current fundamental wave i ;According to the transfer function of the bandpass filter and the low-pass filter, the phase compensation coefficient is obtained, and the phase angle compensator is used to compensate the phase to obtain the compensated voltage fundamental phase θ u ' and the current fundamental phase after compensation θ i '; Coupling coefficient k between primary and secondary coils 12 and the load resistor R L The calculation formula is: Wherein, ω represents the operating frequency of the wireless power transmission system; L1 represents the first inductor in the SS-type two-coil wireless power transmission topology; C1 represents the first capacitor in the SS-type two-coil wireless power transmission topology; L2 represents the second inductor in the SS-type two-coil wireless power transmission topology; C2 represents the second capacitor in the SS-type two-coil wireless power transmission topology; L b Represents the residual inductance in a Class E power amplifier.

5. The closed-loop control method for a single transmitter-side analog circuit of a wireless power transmission system according to claim 1, wherein: In step S4, obtaining the duty cycle includes the following: At the parity-time symmetric operating frequency point within the parity-time symmetry region, the SS-type two-coil wireless power transmission topology in the power transmission structure of the wireless power transmission system has the best output power and transmission efficiency. The calculation formula for its operating frequency within the parity-time symmetry region is: Among them, ω PT represents the operating frequency in the parity-time symmetry region; Γ2=(r2+R L ) / (2L2), R L represents the load resistance in the SS type two-coil wireless power transmission topology, r2 represents the internal resistance of the receiving coil, and L2 represents the second inductor in the SS type two-coil wireless power transmission topology; k 12 Represents the coupling coefficient of the two coils; ω0 represents the frequency of the square wave controlled by the switch tube; Critical coupling coefficient k c The expression is: When k 12 Greater than k c When ω = ω, it indicates that the wireless power transmission system is located in the parity-time symmetry region. At this time, the operating frequency of the system is ω = ω PT ; When k 12 Less than k c When ω = ω, it indicates that the wireless power transmission system is located in the symmetry breaking region. At this time, the operating frequency of the system is ω = ω n , where ω n Indicates the natural operating frequency of the wireless power transmission system, C2 represents the second capacitor in the SS type two-coil wireless power transfer topology; when k 12 Equal to k c When , it indicates that the wireless power transmission system is in the critical symmetry area; The expression of the steady-state equation of the class E power amplifier is: Among them, I m represents the fundamental amplitude of the current; C1 represents the first capacitor in the SS type two-coil wireless power transmission topology; L b represents the residual inductance in the class E power amplifier; I1 represents the DC supply current; D represents the duty cycle of the switch tube; φ represents the current phase difference between the switch tube and the class E power amplifier load network; V I Indicates the DC supply voltage; The zero voltage turn-on condition is introduced into the class E power amplifier, and its constraint formula is: By combining the steady-state equation of the class E power amplifier and the constraint formula of the zero voltage conduction condition, the duty cycle D of the switch tube is obtained.

6. A device for the closed-loop control method of a single transmitter-side analog circuit of a wireless power transmission system according to any one of claims 1 to 5, characterized in that: include: Wireless power transmission system power transmission structure, signal detection circuit, receiving side information inversion circuit, transmitting side switch tube control structure and switch tube drive circuit; The input end of the signal detection circuit is connected to the transmitting side of the SS-type two-coil wireless power transmission topology in the power transmission structure of the wireless power transmission system, the output end of the signal detection circuit is connected to the input end of the receiving-side information inversion circuit, the output end of the receiving-side information inversion circuit is connected to the input end of the transmitting-side switch tube control structure and is grounded, the output end of the transmitting-side switch tube control structure is connected to the input end of the switch tube drive circuit, and the output end of the switch tube drive circuit is connected to the Class E power amplifier in the power transmission structure of the wireless power transmission system.

7. The device for the closed-loop control method of a single transmitter-side analog circuit of a wireless power transmission system according to claim 6, characterized in that: The SS type two-coil wireless power transmission topology includes the first inductor L1, the first capacitor C1, the second inductor L2, the second capacitor C2, the transmitting coil internal resistance r1, the receiving coil internal resistance r2 and the load resistor R L ; The first capacitor C1, the first inductor L1, and the transmitting coil internal resistance r1 are located on the transmitting side, the second capacitor C2, the load resistor R L , the internal resistance r2 of the receiving coil, and the second inductor L2 are located on the receiving side; The class E power amplifier includes a choke inductor L f , switch tube D1, switch tube parallel capacitor C3 and residual inductance L b ; Choke inductor L f One end is connected to the positive pole of the DC power supply, the negative pole of the DC power supply is grounded, and the choke inductor L f The other end is connected to the drain of the switch tube D1, one end of the switch tube parallel capacitor C3, and the residual inductance L b The source of the switch tube D1 is connected to the other end of the switch tube parallel capacitor C3 and the residual inductance L b The other end of the connection; In the power transmission structure of the wireless power transmission system, the second inductor L2, the second capacitor C2, and the load resistor R L and the internal resistance r2 of the receiving coil are connected in series to form a series circuit; the choke inductor L f One end is connected to the positive pole of the DC power supply, the negative pole of the DC power supply is grounded, and the choke inductor L f The other end is connected to the drain of the switch tube D1, one end of the switch tube parallel capacitor C3, and the residual inductance L b The source of the switch tube D1 is connected to the other end of the switch tube parallel capacitor C3 and one end of the transmitting coil internal resistance r1 respectively. The residual inductance L b The other end of is connected to one end of the first capacitor C1, the other end of the first capacitor C1 is connected to one end of the first inductor L1, the other end of the first inductor L1 is connected to the other end of the transmitting coil internal resistance r1, and the gate of the switch tube D1 is connected to the output end of the switch tube driving circuit.

8. The device for the closed-loop control method of a single transmitter-side analog circuit of a wireless power transmission system according to claim 7, characterized in that: The inductance of the first inductor L1 is equal to the inductance of the second inductor L2 , and the capacitance of the first capacitor C1 is equal to the capacitance of the second capacitor C2 .

9. The device for the closed-loop control method of a single transmitter-side analog circuit of a wireless power transmission system according to claim 6, characterized in that: The peak detection circuit includes a diode, a capacitor and a resistor; the positive electrode of the diode is connected to the first stage of the bandpass filter output terminal, the negative electrode of the diode is connected to one end of the capacitor and the resistor, the other end of the capacitor and the resistor are connected and connected to the other stage of the bandpass filter output terminal; The output end of the signal detection circuit is connected to the input end of the bandpass filter, the output end of the bandpass filter is respectively connected to the input end of the peak detection circuit and the input end of the first analog multiplier, the output end of the first analog multiplier is connected to the input end of the low-pass filter, the output end of the peak detection circuit is connected to the input end of the second analog multiplier, and the output end of the low-pass filter and the output end of the second analog multiplier are both connected to the parameter information inverse calculator.

10. The device for the closed-loop control method of a single transmitter-side analog circuit of a wireless power transmission system according to claim 6, characterized in that: The parameter information inverse calculator includes a first resistor R C , the second resistor R c , first to sixth transistors T1 to T6 and a current source; Power supply V CC Respectively with the first resistor R C One end of the second resistor R c One end of the first resistor R C The other end is connected to the emitter of the first transistor T1, the emitter of the third transistor T3, and the positive electrode of the first voltage u0 respectively; the second resistor R c The other end is connected to the emitter of the second transistor T2, the emitter of the fourth transistor T4, and the negative electrode of the first voltage u0; the second voltage U X The positive electrode is connected to the base of the first transistor T1 and the base of the fourth transistor T4 respectively; the second voltage U X The negative electrode of the transistor is connected to the base of the second transistor T2 and the base of the third transistor T3 respectively; the collector of the first transistor T1 is connected to the collector of the second transistor T2 and the emitter of the fifth transistor T5 respectively; the collector of the third transistor T3 is connected to the collector of the fourth transistor T4 and the emitter of the sixth transistor T6 respectively; the third voltage U Y The positive electrode is connected to the base of the fifth transistor T5, and the third voltage U Y The negative electrode is connected to the base of the sixth transistor T6; the collector of the fifth transistor T5 is connected to the collector of the sixth transistor T6, and is commonly connected to one end of the current source I, and the other end of the current source I is grounded.

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