Harmonic rejection circuit for an inductively coupled energy transfer system

Abstract

The application provides a harmonic suppression circuit of an inductive coupling energy transmission system, which places an auxiliary receiving circuit with a resonance frequency of 3 times, 5 times, 7 times or 2n+1 (n=1, 2, 3…) times of a fundamental frequency on a secondary side, configures a corresponding voltage stabilizing circuit on a direct current voltage output side of the auxiliary receiving circuit, and realizes a self-power supply function of a power utilization device such as a control circuit on the secondary side, and a quality factor Q of the auxiliary receiving circuit is i The harmonic suppression method is simple, does not affect power transmission of a main circuit, and can improve the efficiency of the inductive coupling energy transmission system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wireless power transmission, and particularly relates to a harmonic suppression circuit of an inductive coupling energy transmission system. BACKGROUND

[0002] The inductive coupling energy transmission system is a new power supply mode for transmitting electric energy to a load in a non-contact manner through electromagnetic induction principle. Since the inductive coupling energy transmission system does not need physical connection, is safe and reliable, and is environmentally friendly, the technology has been widely applied to small-power occasions such as electronic products and medical devices, and large-power occasions such as electric vehicles and rail transit.

[0003] In the inductive coupling energy transmission system, since the output voltage of the high-frequency inverter is a square wave, the square wave voltage contains many harmonic components, thereby causing large current distortion, which may pose a certain threat to the operation of the switching tube and the control circuit, and the loss caused by the harmonics may reduce the transmission efficiency of the system, so it is necessary to suppress the harmonics of the primary current.

[0004] The existing harmonic elimination methods of inductive coupling energy transmission system are to change the conduction angle of inverter or to use phase-shifted ladder wave synthesis method. Li Yong, Mai Ruiqun, Lu Liwen, et al. analyzed the relationship between high-frequency inverter output voltage harmonic distortion and conduction angle in the literature "A Harmonic Elimination and Power Regulation Method for IPT System Using Cascaded Multilevel Technology[J]. Transactions of Electrical Engineering, 2015, 35(20): 5278-5285", and set the conduction angle to 80°-180°, thereby limiting the output power regulation range of the inductive coupling energy transmission system. Shin J G, Shin S, Kim Y, et al. used a two-inverter cascaded inductive coupling energy transmission system to eliminate the 3rd harmonic in the literature "Design and implementation of shaped magnetic-resonance-based wireless power transfer system for roadway-powered moving electric vehicles[J]. IEEE Transactions on Industry Electronics, 2014, 61(3): 1179-1192", but this method increases the number of inverters used, and the engineering cost is also increased accordingly; Fan Manyi, Shi Liming, Yin Zhengang, et al. used a three-inverter cascaded inductive coupling energy transmission system to eliminate the 3rd and 5th harmonics in the literature "Harmonic Elimination and Pulse Density Power Regulation Method for Inductive Power Transfer System Based on Ladder Wave Synthesis Technology[J]. Proceedings of the Chinese Institute of Electrical Engineers, 2017, 37(22): 6516-6522", and similarly, the use of this technology will further increase the engineering cost and control complexity, which is not conducive to engineering implementation; Cochran Spencer, Zhao Chongwen, Costinett Daniel, et al. used a multi-level switched capacitor to synthesize a ladder wave to eliminate harmonics in the literature "Multilevel switched-capacitor AC-DC step-down rectifier for wireless charging with reduced conduction loss and harmonic content[J]. IEEE Transactions on Power Electronics, DOI: 10.1109 / TPEL.2022.314 1607", and similarly, this method increases the number of capacitors and switches, and the control is relatively complex, which increases the engineering cost.

[0005] Currently, the research on the original side current harmonic suppression technology of the inductive coupling energy transmission system is relatively less, and there is no better solution to the above problems. SUMMARY

[0006] In order to effectively suppress the current harmonics in the inductive coupling energy transmission system, the application proposes a harmonic suppression circuit of the inductive coupling energy transmission system to overcome the above problems or at least partially solve the above problems. At the same time, the inductive coupling energy transmission system using the auxiliary receiving circuit provides the voltage required by the control circuit on the secondary side, that is, realizes the self-power function of the control circuit and other power devices on the secondary side.

[0007] In order to achieve the above purpose, the technical scheme adopted by the application is:

[0008] A harmonic suppression circuit of an inductive coupling energy transmission system, which is composed of a primary side and a secondary side, the primary side includes a primary side DC voltage source, a high-frequency inverter, a loss equivalent resistor, a primary side compensation capacitor and a primary side transmitting coil; the secondary side includes a main receiving coil, a compensation capacitor, a loss equivalent resistor, a first rectifier filter circuit and a resistance load of a main receiving circuit of the secondary side; the DC voltage source of the primary side is connected to the input end of the high-frequency inverter, and the output end of the high-frequency inverter is connected to the loss equivalent resistor, the primary side compensation capacitor and the primary side transmitting coil in series; the main receiving coil, the compensation capacitor and the loss equivalent resistor of the main receiving circuit of the secondary side are connected in series and connected to the input end of the first rectifier filter circuit, and the output end of the first rectifier filter circuit is connected to the resistance load; further comprising a compensation network adopting a series-series topology, characterized in that: the compensation network is an auxiliary receiving circuit arranged on the secondary side, including an auxiliary receiving coil, a compensation capacitor, a loss equivalent resistor, a second rectifier filter circuit and a resistance load of the auxiliary receiving circuit of the secondary side, and a corresponding power and voltage level voltage stabilizing circuit; the auxiliary receiving coil, the compensation capacitor and the loss equivalent resistor of the auxiliary receiving circuit of the secondary side are connected in series and connected to the input end of the second rectifier filter circuit, and the output end of the second rectifier filter circuit is connected to the resistance load and the corresponding power and voltage level voltage stabilizing circuit; the working frequency f r of the high-frequency inverter is equal to the resonance frequency of the primary side circuit and the main receiving circuit of the secondary side, and the resonance frequency f si of the auxiliary receiving circuit of the secondary side is equal to the current harmonic frequency to be suppressed, wherein i is the harmonic number to be suppressed (i=3, 5, 7, …, 2n+1; n≥1).

[0009] Further, the quality factor Q i of the auxiliary receiving circuit of the secondary side is set to a higher value, that is, Q i ≥25, wherein i is the harmonic number to be suppressed (i=3, 5, 7, …, 2n+1; n≥1).

[0010] Further, the primary side transmitting coil self-inductance L p , the primary side compensation capacitor value C p and the secondary side main receiving circuit main receiving coil self-inductance L s , the compensation capacitor value C s , the high-frequency inverter operating frequency f r is calculated as:

[0011]

[0012] Further, the secondary side auxiliary receiving circuit resonance frequency f si satisfies:

[0013] f si = i·f r (i=3,5,7,…,2n+1;n≥1).

[0014] Further, the secondary side auxiliary receiving circuit auxiliary receiving coil self-inductance L si , the compensation capacitor value C si parameters satisfy the following relationship:

[0015]

[0016] Where i is the harmonic number to be suppressed (i=3,5,7,…,2n+1;n≥1).

[0017] Further, the secondary side auxiliary receiving circuit quality factor Q i and related parameter expressions are:

[0018]

[0019] Where ω si =2πf si is the auxiliary receiving circuit resonance angular frequency, r si is the auxiliary receiving circuit loss equivalent resistance value, R i is the resistance load value of the auxiliary receiving circuit, R a is the equivalent input resistance value of the voltage stabilizing circuit, V in , I in are the input voltage and input current of the voltage stabilizing circuit, R i ' is the resistance value of R i in parallel with R a , R ei is the auxiliary receiving circuit AC equivalent resistance.

[0020] Further, the output power of the secondary side auxiliary receiving circuit is used for power consumption of the secondary side control circuit and other power consumption equipment.

[0021] Compared with the prior art, the present application has the advantages of:

[0022] 1. By adding an auxiliary receiving circuit, the current harmonics are reduced without affecting the power regulation range of the inductive coupling energy transmission system.

[0023] 2. The high-frequency inverter only needs to use simple phase-shift control, and the control is relatively simple.

[0024] 3. The harmonic power received by the auxiliary receiving circuit is relatively small, so the rectifier circuit can select a rectifier circuit with a smaller voltage and current level. By reasonably designing the auxiliary receiving circuit receiving coil, compensation capacitor and resistance load, the volume of the auxiliary receiving circuit can be reduced, and the engineering cost can be reduced.

[0025] 4. By configuring a required power and voltage level voltage stabilizing circuit on the DC voltage output side of the auxiliary receiving circuit, power can be supplied to the control circuit and other electrical equipment on the secondary side, realizing the self-power function of the control circuit and other electrical equipment on the secondary side of the inductive coupling energy transmission system, and realizing the effective application of harmonic energy. BRIEF DESCRIPTION OF DRAWINGS

[0026] The present application will be further described below in conjunction with the drawings and specific embodiments.

[0027] Figure 1 The auxiliary receiving circuit-based inductive coupling energy transmission system harmonic suppression circuit structure of the present application;

[0028] Figure 2 The influence of auxiliary receiving circuits with different quality factors on the main receiving circuit;

[0029] Figure 3 The primary current waveform and THD value of the auxiliary receiving circuit-based inductive coupling energy transmission system under the present application;

[0030] Figure 4 The primary current FFT waveform of the auxiliary receiving circuit-based inductive coupling energy transmission system under the present application;

[0031] Figure 5 The primary current waveform and THD value of the traditional inductive coupling energy transmission system circuit;

[0032] Figure 6 The primary current FFT waveform of the traditional inductive coupling energy transmission system circuit;

[0033] Figure 7 The current waveform of the main receiving circuit and the auxiliary receiving circuit of the auxiliary receiving circuit-based inductive coupling energy transmission system under the present application;

[0034] Figure 8 The DC voltage waveform output by the auxiliary receiving circuit-based inductive coupling energy transmission system receiving coil and the voltage waveform output by the voltage stabilizing circuit are obtained.

[0035] Figure 1 In the application, 1 is the primary side, 101 is a primary side DC voltage source, 102 is a high-frequency inverter, 103 is a loss equivalent resistor, 104 is a primary side compensation capacitor, and 105 is a primary side transmitting coil; 2 is the secondary side, 210 is a secondary side main receiving circuit, 220 is a secondary side auxiliary receiving circuit, 211 is a main receiving coil of the secondary side main receiving circuit, 212 is a compensation capacitor, 213 is a loss equivalent resistor, 214 is a first rectifier filter circuit, and 215 is a resistor load; 221 is an auxiliary receiving coil of the secondary side auxiliary receiving circuit, 222 is a compensation capacitor, 223 is a loss equivalent resistor, 224 is a second rectifier filter circuit, 225 is a resistor load, 226 is a voltage stabilizing circuit corresponding to the power and voltage level, 121 is mutual inductance M between the primary side transmitting coil and the secondary side main receiving coil, and 122 is mutual inductance M3 between the primary side transmitting coil and the auxiliary receiving coil. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the examples of the application. The described embodiments are only some of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the application.

[0037] The inductive coupling energy transmission system harmonic suppression circuit of the application is composed of a primary side device and a secondary side composed of a secondary side main receiving circuit and a secondary side auxiliary receiving circuit. The primary side includes a primary side DC voltage source, a high-frequency inverter, a loss equivalent resistor, a primary side compensation capacitor, and a primary side transmitting coil. The secondary side includes a main receiving coil of the secondary side main receiving circuit, a compensation capacitor, a loss equivalent resistor, a first rectifier filter circuit, and a resistor load. The harmonic suppression circuit further includes mutual inductance M between the primary side transmitting coil and the secondary side main receiving coil and mutual inductance M3 between the primary side transmitting coil and the auxiliary receiving coil. i The high-frequency inverter is composed of bidirectional controllable power switching devices S1, S2, S3, and S4. The first rectifier filter circuit is composed of diodes D1, D2, D3, and D4 and a filter capacitor. The filter capacitor capacity is represented as C o The voltage of the primary side DC voltage source is represented as v dc The self-inductance of the primary side transmitting coil is represented as L p The resistance value of the loss equivalent resistor is represented as r p, the compensation capacitor value is represented as C p , the main receiving coil self-inductance of the secondary side main receiving circuit is represented as L s , the compensation capacitor value is represented as C s , the loss equivalent resistance resistance value is represented as r s , and the resistance load resistance value is represented as R.

[0038] The compensation network of the application adopts the series-series compensation topology circuit commonly used in the inductive coupling energy transmission system, and sets an auxiliary receiving circuit on the secondary side, mainly including an auxiliary receiving coil, a compensation capacitor, a loss equivalent resistance, a second rectifier filter circuit, a resistance load, and a voltage stabilizing circuit of corresponding power and voltage level. i1 , D i2 , D i3 , D i4 and a filter capacitor. The filter capacitor value is represented as C oi . The auxiliary receiving coil self-inductance of the secondary side auxiliary receiving circuit is represented as L si , the compensation capacitor value is represented as C si , the loss equivalent resistance resistance value is represented as r si , and the resistance load resistance value is represented as R i . Wherein, i is the harmonic number to be suppressed (i=3, 5, 7, …, 2n+1; n≥1).

[0039] The positive and negative poles of the primary side DC voltage source are respectively connected with the collector of the bidirectional controllable power switch device S1 and the emitter of the bidirectional controllable power switch device S2, and the emitter of the bidirectional controllable power switch device S1 is connected with the collector of the bidirectional controllable power switch device S2 as one output end of the high-frequency inverter, and the emitter of the bidirectional controllable power switch device S2 is connected with the collector of the bidirectional controllable power switch device S4 as another output end of the high-frequency inverter.

[0040] The cathodes of diodes D1 and D3 and the anodes of diodes D2 and D4 are respectively connected with the positive and negative poles of a filter capacitor, the anode of diode D1 and the cathode of diode D2 are connected as one input end of the first rectifier filter circuit, and the anode of diode D3 and the cathode of diode D4 are connected as another input end of the first rectifier filter circuit, wherein the filter capacitor value is represented as C o ; the cathodes of diodes D i1 , D i3 and the anodes of diodes D i2 , D i4 are respectively connected with the positive and negative poles of a filter capacitor, and the anodes of diodes D i1 and the cathodes of diodes Di2 The cathode of diode D is connected as an input terminal of the second rectifier filter circuit. i3 anode and diode D i4 The cathode is connected as another input terminal of the second rectifier filter circuit, and the capacitance value of the filter capacitor is expressed as C. oi .

[0041] The high-frequency inverter operates at frequency f. r It equals the resonant frequency of the primary side circuit and the secondary side main receiving circuit, and the resonant frequency f of the auxiliary receiving circuit. si It is equal to the frequency of the current harmonic to be suppressed, and the quality factor Q of the auxiliary receiving circuit is... i It should be set to a higher value, i.e., Q. i ≥25.

[0042] The equivalent resistance r of the loss on the primary side is obtained by measuring with an LCR meter. p The capacitance value C of the primary side compensation capacitor p , self-inductance L of the primary side transmitting coil p The self-inductance L of the main receiving coil in the secondary side main receiving circuit s The capacitance value C of the compensation capacitor s The equivalent resistance value r of the loss s And the self-inductance L of the auxiliary receiving coil in the secondary-side auxiliary receiving circuit si The capacitance value C of the compensation capacitor si The equivalent resistance value r of the loss si Parameters; the resistance values ​​R and R' of the load are obtained by measuring with a multimeter. i The input voltage V of the voltage regulator circuit is obtained by measuring with an oscilloscope. in and input current I in .

[0043] The operating frequency f of the high-frequency inverter r for:

[0044]

[0045] The resonant frequency f of the auxiliary receiving circuit si It should meet the following requirements:

[0046] f si =i·f r (i = 3, 5, 7, ..., 2n+1; n ≥ 1)

[0047] According to the resonant frequency f of the auxiliary receiving circuit si The self-inductance L of the auxiliary receiving coil in the auxiliary receiving circuit si The capacitance value C of the compensation capacitor si The following relationship should be satisfied:

[0048]

[0049] Quality factor Q of auxiliary receiving circuit i And the related parameter expression is:

[0050]

[0051] Wherein, R i Is the resistance load resistance value of auxiliary receiving circuit, R a Is the equivalent input resistance value of voltage stabilizing circuit, V in , I in Respectively, the input voltage of voltage stabilizing circuit, input current, R i 'Is the resistance value of R i Parallel R a , R ei Is the ac equivalent resistance of auxiliary receiving circuit, r si Is the loss equivalent resistance value of auxiliary receiving circuit, ω si = 2πf si Is the resonance angular frequency of auxiliary receiving circuit.

[0052] From the above formula, it can be seen that the quality factor Q i Related to the auxiliary receiving coil self-inductance L si And resistance value R i 'Of auxiliary receiving circuit, blindly increasing the self-inductance of auxiliary receiving coil of auxiliary receiving circuit will increase the system volume and engineering cost, therefore, the quality factor of auxiliary receiving circuit is selected to be reduced to improve the quality factor of auxiliary receiving circuit and reduce the volume of inductive coupling energy transmission system. It is worth noting that the existence of the resistance load of the auxiliary receiving circuit is necessary, which can ensure that the inductive coupling energy transmission system can still operate safely and stably when the control circuit and other electrical equipment on the secondary side are disconnected.

[0053] By placing the auxiliary receiving circuit with high quality factor on the secondary side, the current harmonic amplitude can be effectively suppressed, the harmonic distortion rate can be reduced, and the inductive coupling energy transmission system efficiency can be improved. At the same time, the inductive coupling energy transmission system with auxiliary receiving circuit can provide the voltage required by the control circuit on the secondary side, that is, realize the self-power function of the control circuit and other electrical equipment on the secondary side.

[0054] The theoretical analysis of the current harmonic amplitude suppression of the present application is as follows:

[0055] Since the high-frequency inverter usually adopts phase-shift control, the dead time of the high-frequency inverter is ignored, therefore, the expression of the root mean square (RMS) value of the i-th harmonic component of the input voltage v ab Of compensation network is:

[0056]

[0057] Among them, v dc α is the voltage value of the DC voltage source on the primary side, and α is the phase shift angle.

[0058] Because the designed auxiliary receiving circuit has a high quality factor, the mutual influence between the receiving coils can be ignored. Therefore, the reflection impedance Z of the auxiliary receiving circuit is... mi The expression is:

[0059]

[0060] Among them, M i R represents the mutual inductance between the transmitting coil and the auxiliary receiving coil of the auxiliary receiving circuit, where j is an imaginary number. ei To assist the AC equivalent resistance of the receiving circuit, L si C si r si These represent the self-inductance of the receiving coil, the capacitance of the compensation capacitor, and the equivalent resistance of the loss in the auxiliary receiving circuit, respectively. si =2πf si This is the resonant angular frequency of the auxiliary receiving circuit.

[0061] The frequency of the auxiliary receiving circuit designed in this invention is equal to the harmonic frequency, Z. mi To further simplify:

[0062]

[0063] Therefore, the amplitude I of the i-th primary harmonic current pi The expression is:

[0064]

[0065] Among them, L p C p r p These represent the self-inductance of the primary side transmitting coil, the capacitance of the compensation capacitor, and the equivalent resistance of the loss, respectively.

[0066] As can be seen from the above formula, due to the higher quality factor Q i The design and placement of the auxiliary receiving circuit can reduce the amplitude of the primary current harmonics. When the secondary-side voltage regulator circuit is not connected to control circuits or other electrical equipment, R i '=R i However, when the voltage regulator circuit on the secondary side is connected to control circuits or other electrical equipment for operation, Resistance value R i 'Further reduction, reflection impedance Z mi As the current increases further, the amplitude of the current harmonics will also decrease further.

[0067] Therefore, reducing the load resistance of the auxiliary receiving circuit can not only improve the quality factor of the auxiliary receiving circuit, but also effectively reduce the current harmonic amplitude.

[0068] In summary, the auxiliary receiving circuit with high quality factor placed on the secondary side can effectively reduce the current harmonic amplitude, reduce the original side current harmonic distortion rate, and improve the system efficiency.

[0069] The application will be described in detail below with specific embodiments.

[0070] Taking the suppression of the third (i=3) current harmonic as an example, the circuit diagram of the harmonic suppression circuit of the inductive coupling energy transmission system is obtained as shown in Figure 1 .

[0071] As shown in Figure 1 , the harmonic suppression circuit is composed of the primary side 1 composed of the primary side device and the secondary side 2 composed of the secondary side main receiving circuit 210 and the secondary side auxiliary receiving circuit 220. The primary side includes the primary side DC voltage source 101, the high-frequency inverter 102, the loss equivalent resistor 103, the primary side compensation capacitor 104, and the primary side transmitting coil 105. The secondary side includes the main receiving coil 211, the compensation capacitor 212, the loss equivalent resistor 213, the first rectifier filter circuit 214, and the resistor load 215 of the secondary side main receiving circuit. The secondary side also includes the auxiliary receiving coil 221, the compensation capacitor 222, the loss equivalent resistor 223, the second rectifier filter circuit 224, the resistor load 225, and the voltage stabilizing circuit 226 of the corresponding power and voltage level of the secondary side auxiliary receiving circuit. The harmonic suppression circuit also includes the mutual inductance M1 121 between the primary side transmitting coil and the secondary side main receiving coil, and the mutual inductance M3 122 between the primary side transmitting coil and the auxiliary receiving coil. The high-frequency inverter 102 is composed of bidirectional controllable power switching devices S1, S2, S3, and S4. The first rectifier filter circuit 214 is composed of diodes D1, D2, D3, and D4, and a filter capacitor (with a capacitance value of C o ). The second rectifier filter circuit 224 is composed of diodes D 31 , D 32 , D 33 , D 34 , and a filter capacitor (with a capacitance value of C o3 ). The voltage of the primary side DC voltage source is represented as v dc . The self-inductance of the primary side transmitting coil is represented as L p , the resistance value of the loss equivalent resistor is represented as r p , and the capacitance value of the compensation capacitor is represented as C p . The self-inductance of the main receiving coil of the secondary side main receiving circuit is represented as L s , and the capacitance value of the compensation capacitor is represented as C s, the loss equivalent resistance value is represented as r s , the resistance load value is represented as R. The auxiliary receiving coil self-inductance of the secondary side auxiliary receiving circuit is represented as L s3 , the compensation capacitor value is represented as C s3 , the loss equivalent resistance value is represented as r s3 , the resistance load value is represented as R3.

[0072] Figure 1 In the embodiment, the primary side DC voltage source 101 is connected to the input end of the high frequency inverter 102, and the output end of the high frequency inverter 102 is connected in series with the loss equivalent resistance 103, the primary side compensation capacitor 104 and the primary side transmitting coil 105. The main receiving coil 211, the compensation capacitor 212 and the loss equivalent resistance 213 of the secondary side main receiving circuit are connected in series and connected to the input end of the first rectification filter circuit 214, and the output end of the first rectification filter circuit 214 is connected with the resistance load 215. The auxiliary receiving coil 221, the compensation capacitor 222 and the loss equivalent resistance 223 of the secondary side auxiliary receiving circuit are connected in series and connected to the input end of the second rectification filter circuit 224, and the output end of the second rectification filter circuit 224 is connected with the resistance load 225 and the corresponding power and voltage level voltage stabilizing circuit 226.

[0073] The primary side loss equivalent resistance value r p = 0.033 Ω, the primary side compensation capacitor value C p = 1.27 μF, the primary side transmitting coil self-inductance L p = 22.14 μH, the secondary side main receiving circuit main receiving coil self-inductance L s = 980 μH, the compensation capacitor value C s = 28.7 nF, the loss equivalent resistance value r s = 0.495 Ω, and the secondary side auxiliary receiving circuit auxiliary receiving coil self-inductance L s3 = 965 μH, the compensation capacitor value C s3 = 3.24 nF, the loss equivalent resistance value r s3 = 0.5 Ω; the resistance load value R = 15 Ω, R3 = 3 Ω is measured by the multimeter; the voltage stabilizing circuit input voltage V in = 2.1 V, the input current I in = 2.4 A is measured by the oscilloscope.

[0074] The high frequency inverter working frequency f r is:

[0075]

[0076] To suppress the third harmonic in the primary current, the resonance frequency f s3 Should be satisfied:

[0077] f s3 = 3f r = 90 kHz

[0078] Where f r Is the fundamental frequency.

[0079] The self-inductance L s3 of the auxiliary receiving coil in the auxiliary receiving circuit, the compensation capacitance value C s3 Should be satisfied:

[0080]

[0081] The quality factor Q3 of the auxiliary receiving circuit is:

[0082]

[0083] Where R3 is the resistance load value of the auxiliary receiving circuit, R a Is the equivalent input resistance value of the voltage stabilizing circuit, V in , I in The input voltage and input current of the voltage stabilizing circuit, R3' is the parallel resistance value of R3 and R a , R e3 Is the AC equivalent resistance of the auxiliary receiving circuit, r s3 Is the loss equivalent resistance value of the auxiliary receiving circuit, ω s3 = 2πf s3 = 565486.68 rad / s is the resonance angular frequency of the auxiliary receiving circuit.

[0084] Under different working frequencies of the high-frequency inverter, the current amplitude I s3 Flowing through the auxiliary receiving circuit is expressed as:

[0085]

[0086] Where f is the working frequency of the high-frequency inverter, ω = 2πf is the working angular frequency of the high-frequency inverter, M3 is the mutual inductance between the transmitting coil and the auxiliary receiving circuit receiving coil, I p Is the primary transmitting coil current.

[0087] Under different quality factors Q3, the unit current amplitude flowing through the auxiliary receiving circuit changes with frequency as shown in Figure 2 . From Figure 2It can be seen that the current-frequency curve presents a bell shape, and the current peak value is near the resonance frequency point of the auxiliary receiving circuit, and the auxiliary receiving circuit presents high resistance to the fundamental power transmission, so the auxiliary receiving circuit has little influence on the fundamental power transmission. When Q3 is larger, the current-frequency curve is more sharp, and the mutual influence between the receiving coils is further reduced, but the problem of quality factor and engineering cost needs to be considered comprehensively.

[0088] The reflection impedance expression of the auxiliary receiving circuit to the primary side third harmonic circuit is:

[0089]

[0090] The amplitude expression of the primary side third harmonic current is:

[0091]

[0092] Wherein, V ab3 is the third harmonic voltage RMS value of the compensation network input voltage v ab , L p , C p , r p are the self-inductance of the primary side transmitting coil, the compensation capacitor value and the loss equivalent resistance value respectively.

[0093] Therefore, the third current harmonic amplitude can be effectively suppressed, and the primary side current harmonic distortion rate is reduced.

[0094] In the embodiment, the voltage stabilizing circuit realizes 5V constant voltage output.

[0095] Figure 3 The primary side current waveform and THD value when the phase shift angle α of the present application is 0° are shown in the figure, and the THD is 0.88%.

[0096] Figure 4 The FFT waveform of the primary side current when the present application is adopted is shown in the figure, and the third current harmonic amplitude is 0.60A.

[0097] Figure 5 The primary side current waveform and THD value when the phase shift angle α of the traditional inductive coupling energy transmission system is 0° are shown in the figure, and the THD is 2.09%.

[0098] Figure 6 The FFT waveform of the primary side current when the traditional inductive coupling energy transmission system is adopted is shown in the figure, and the third current harmonic amplitude is 3.86A.

[0099] Figure 7 The current waveforms of the main receiving circuit and the auxiliary receiving circuit when the present application is adopted are shown in the figure, and the current i s3 of the auxiliary receiving circuit is 3 times the frequency of the current i s1 of the main receiving circuit.

[0100] Figure 8 The DC voltage waveforms output by the main receiving circuit, the auxiliary receiving circuit and the voltage stabilizing circuit under the application are as follows: the DC output voltage of the main receiving circuit is v o1 , the DC voltage output by the auxiliary receiving circuit is v o3 , and the DC voltage output by the voltage stabilizing circuit is V out The voltage stabilizing circuit can realize 5V constant voltage output, thereby supplying power for the control circuit and other power consumption devices.

[0101] In summary, the application has the advantages of simple control, large power adjustable range, effective reduction of current harmonic amplitude and current harmonic distortion rate, realization of self-power function of the control circuit and other power consumption devices on the secondary side of the inductive coupling energy transmission system, and the like.

[0102] Although the above describes the illustrative specific embodiments of the application in order to facilitate the understanding of the application by the person skilled in the art, it should be clear that the application is not limited to the scope of the specific embodiments, and any modification, equivalent replacement and improvement made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A harmonic rejection circuit for an inductively coupled energy transfer system, characterized by: The harmonic suppression circuit is composed of a primary side and a secondary side, the primary side includes a primary side DC voltage source, a high-frequency inverter, a loss equivalent resistor, a primary side compensation capacitor and a primary side transmitting coil; the secondary side includes a main receiving coil, a compensation capacitor, a loss equivalent resistor, a first rectifier filter circuit and a resistance load of a main receiving circuit of the secondary side; the DC voltage source of the primary side is connected to the input end of the high-frequency inverter, the output end of the high-frequency inverter is connected to the loss equivalent resistor, the primary side compensation capacitor and the primary side transmitting coil in series; the main receiving coil, the compensation capacitor and the loss equivalent resistor of the main receiving circuit of the secondary side are connected in series and connected to the input end of the first rectifier filter circuit, the output end of the first rectifier filter circuit is connected to the resistance load; further comprising a compensation network adopting a series-serial type topology, the compensation network is an auxiliary receiving circuit arranged in the secondary side, including an auxiliary receiving coil, a compensation capacitor, a loss equivalent resistor, a second rectifier filter circuit and a resistance load of the auxiliary receiving circuit of the secondary side and a corresponding power and voltage level voltage stabilizing circuit; The auxiliary receiving coil, compensation capacitor and loss equivalent resistance of the secondary side auxiliary receiving circuit are connected in series in turn and connected to the input end of the second rectification filter circuit, and the output end of the second rectification filter circuit is connected with a resistance load and a voltage stabilizing circuit of corresponding power and voltage level; the working frequency f r of the high-frequency inverter is equal to the resonance frequency of the primary side circuit and the secondary side main receiving circuit, and the resonance frequency f si of the secondary side auxiliary receiving circuit is equal to the current harmonic frequency to be suppressed, wherein i is the harmonic number to be suppressed, i=3, 5, 7, …, 2n+1; n≥1.

2. A harmonic rejection circuit for an inductively coupled power transfer system as claimed in claim 1, wherein: The quality factor Q of the auxiliary receiving circuit on the secondary side i is set to ≥ 25, where i is the number of harmonics to be suppressed.

3. A harmonic rejection circuit for an inductively coupled power transfer system as claimed in claim 1 or 2, wherein: The primary side transmitting coil self-inductance L is measured by the LCR meter p The primary side compensation capacitor value C p And the main receiving coil self-inductance L of the secondary side main receiving circuit s The compensation capacitor value C s The working frequency f of the high-frequency inverter is calculated as r ​ 。 4. A harmonic rejection circuit for an inductively coupled power transfer system as claimed in claim 1 or 2, wherein: The resonance frequency f of the secondary side auxiliary receiving circuit si satisfies: 。 5. A harmonic rejection circuit for an inductively coupled power transfer system as claimed in claim 1 or 2, wherein: The self-inductance L of the auxiliary receiving coil of the secondary side auxiliary receiving circuit si , the compensation capacitance value C si The parameters satisfy the following relationship: ； Wherein, i is the harmonic number to be suppressed.

6. A harmonic rejection circuit for an inductively coupled power transfer system as claimed in claim 5, wherein: Quality factor Q of the secondary side auxiliary receiving circuit i And the related parameter expression is: ； Wherein, ω si = 2πf si is the auxiliary receiving circuit resonance angular frequency, r si is the auxiliary receiving circuit loss equivalent resistance value, R i is the auxiliary receiving circuit resistance load resistance value, R a is the equivalent input resistance value of the voltage stabilizing circuit, V in , I in is the input voltage and input current of the voltage stabilizing circuit, respectively, is the R i parallel R a resistance value, R ei is the auxiliary receiving circuit AC equivalent resistance.

7. A harmonic rejection circuit for an inductively coupled power transfer system as claimed in claim 1 or 2, wherein: The output electric energy of the auxiliary receiving circuit of the secondary side is used for the power consumption of the control circuit of the secondary side.

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