A design method for double-terminal compensation network of WPT system with strong anti-bias

Abstract

The present invention discloses a method for designing a double-end compensation network of a WPT system with strong anti-offset performance, comprising the following steps: first, establishing a WPT system based on an SS compensation topology; second, introducing an inverse G-type compensation network at a detuned transmitting end of the WPT system; and third, introducing an impedance inversion network between the compensation network and a load at a receiving end of the WPT system to complete the double-end design of the WPT system. The present invention introduces an inverse G-type compensation network at a transmitting end and an impedance inversion network at a receiving end, so that the WPT system can achieve an output power level equivalent to that of a full-resonance SS network at an optimal coupling coefficient, and realizes that the output power fluctuation degree of the receiving end can be arbitrarily configured, thereby improving the output power level of the system, and at the same time realizes the stability of the output power within a wide coupling coefficient range, thereby expanding the spatial freedom of the power receiving device.

Description

Technical Field

[0001] The present invention relates to the field of equipment technology, and in particular to a design method for a double-terminal compensation network of a WPT system with strong anti-deviation performance. Background Art

[0002] Wireless Power Transfer (WPT) technology has been widely used in consumer electronics, biological engineering, household appliances and other fields due to its many unique advantages such as safe, flexible and reliable power supply.

[0003] In order to enhance the practicality and reliability of the system, the WPT system needs to have the ability to output power smoothly within a wider coupling coefficient range. In practical applications, changes in the relative positions of the transmitting and receiving coils will cause large fluctuations in the power output of the system, thereby affecting the control efficiency and reliability of the system. In existing research, three methods are usually used to improve the stability of the system output power: designing control strategies, optimizing coil structures, and improving compensation topologies.

[0004] Traditional resonant SS and LCC-S compensation topologies are sensitive to the coupling coefficient and have large output power fluctuations. The wireless power transmission system pursues stable power transmission within a wide coupling coefficient range. Therefore, the traditional topology is not suitable for occasions where the coupling coefficient changes drastically. Therefore, the present invention proposes a double-ended compensation network design method for a WPT system with strong anti-offset performance to solve the problems existing in the prior art. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to propose a two-end compensation network design method for a WPT system with strong anti-bias. The two-end compensation network design method for a WPT system with strong anti-bias introduces an inverse Г-type compensation network at the transmitting end and an impedance inversion network at the receiving end, thereby achieving arbitrary configuration of the output power fluctuation degree at the receiving end, improving the output power level of the system, and achieving the stability of the output power within a wide coupling coefficient range, thereby expanding the spatial freedom of the powered equipment.

[0006] To achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: a design method of a double-terminal compensation network for a WPT system with strong anti-bias, comprising the following steps:

[0007] Step 1: Establish a WPT system based on SS compensation topology and perform detuning analysis on the transmitter output power;

[0008] Step 2: Introduce an inverse Г-type compensation network into the detuned transmitter of the WPT system established in step 1, and use the reflection impedance theory to represent the entire receiving circuit equivalently to form an improved LCC-S circuit topology, and then simplify the circuit equivalently according to the circuit theory;

[0009] Step 3: Based on the introduction of the inverse Г-type compensation network at the transmitting end, an impedance inversion network is introduced between the compensation network and the load at the receiving end of the WPT system to transform the equivalent load resistance, forming an improved LCC-CLC circuit topology and completing the double-end design of the WPT system.

[0010] A further improvement is that in the equivalent simplification process in step 2, the following relationship holds true:

[0011]

[0012] in, is the equivalent power supply voltage, is the full-bridge inverter output voltage, is the system operating angular frequency, To compensate the network inductance, To compensate for network capacitance;

[0013] Let the adjustment variable

[0014] From the above formula (1), we can get the inverter output voltage After equivalent transformation by the inverse Г-type compensation network, the voltage amplitude at the transmitting end can be adjusted;

[0015] In the equivalent simplified circuit, let and:

[0016] in, is the equivalent resistance, X is the reactance, is the equivalent power inductance, is the self-inductance of the transmitting coil, Compensation capacitor for the transmitter;

[0017] When reactance and resistance exist in a circuit at the same time, When the load power is the largest, the system input impedance angle is 45°. for The calculated reflected resistance is ; is the coupling coefficient, is the coupling coefficient when the system output power reaches the maximum;

[0018] Combining equations (1) to (3), we can get the maximum output power: for:

[0019] From formula (4), we can get the adjustment variable Make changes to the maximum output power;

[0020] Based on the above derivation process, the following equation is established:

[0021] By configuring the inductor in formula (5) and capacitor Parameters compensate for the power drop caused by detuning compensation.

[0022] A further improvement is that: the WPT system connection relationship after the introduction of the inverse Г-type compensation network at the transmitting end and the introduction of the impedance inversion network at the receiving end is the power supply After connecting to the inverse Г-type compensation network and the capacitor and inductance Connect in series to form the transmitter; inductor With capacitor After connecting in series, connect to the impedance inverter network, and then connect the load in series The receiving end is composed of the impedance inversion network: The T-shaped structure Series connection.

[0023] The beneficial effects of the present invention are as follows: the present invention introduces an inverse G-type compensation network at the transmitting end and an impedance inversion network at the receiving end, thereby achieving arbitrary configuration of the output power fluctuation degree of the receiving end, improving the output power level of the system, and achieving the stability of the output power within a wide coupling coefficient range, thereby expanding the spatial freedom of the powered device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a circuit diagram of the WPT system based on the SS compensation topology of the present invention.

[0025] Figure 2 The detuned SS topology of the present invention Graph.

[0026] Figure 3 The output power characteristic curves of the two compensation methods of the present invention are shown in FIG.

[0027] Figure 4 This is the circuit diagram of the “improved LCC-S” compensation topology of the present invention.

[0028] Figure 5 This is a simplified schematic diagram of the "improved LCC-S" compensation topology circuit of the present invention.

[0029] Figure 6 The output power characteristic curve diagram of the present invention under different compensation modes.

[0030] Figure 7 This is the “improved LCC-CLC” compensation topology circuit diagram of the present invention.

[0031] Figure 8 The three improved compensation topologies of the present invention are Schematic diagram.

[0032] Fig. 9 The three improved compensation topologies of the present invention are Graph.

[0033] Fig.10 The inverter output voltage and current waveform diagram of a typical coupling coefficient in the experimental verification process of the present invention.

[0034] Fig.11 The output power curves of three improved compensation topologies in the experimental verification process of the present invention are shown.

[0035] Fig.12 The efficiency characteristic curves of three improved compensation topologies in the experimental verification process of the present invention are shown. DETAILED DESCRIPTION

[0036] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0037] according to Figure 1-Figure 12 As shown, this embodiment provides a method for designing a double-end compensation network for a WPT system with strong anti-offset performance, including anti-offset design of a detuned SS compensation network, parameter design of an "inverse Г-type compensation network" at the transmitting end, and parameter design and experimental verification of an "impedance inversion network" at the receiving end.

[0038] 1. Anti-offset design method of detuned SS compensation network

[0039] As the instruction manual Figure 1 As shown in the figure, it is a WPT system based on SS compensation topology, where E is the DC power supply voltage, , are the output voltage and transmitter current of the full-bridge inverter respectively, , are the output voltage and the receiving current respectively. , are the self-inductances of the transmitting coil and the receiving coil, , are the compensation capacitors at the transmitting end and the receiving end, respectively, and M is the mutual inductance between the transmitting coil and the receiving coil. To simplify the analysis, the parasitic resistance at the transmitting end and the receiving end is not considered.

[0040] Write the KVL equation for this SS compensation topology: in is the system operating angular frequency, is the coupling coefficient between the transmitting coil and the receiving coil.

[0041] The receiving end adopts full compensation, that is:

[0042] Transmitter capacitance Partial compensation of transmitter inductance

[0043]

[0044] in, is called the detuning rate, Indicates the absolute value of *. Figure 1 The circuit shown is a detuned SS compensation topology.

[0045] Substituting equation (9) into equation (6), the output power of the detuned SS compensation topology is obtained as:

[0046]

[0047] When the detuning rate , that is, when both the transmitter and the receiver are resonant, the system output power is:

[0048]

[0049] According to formula (10), when other parameters in the system are known, the output power It can be regarded as the coupling coefficient The function of The preset coupling coefficient varies from arrive , and satisfy:

[0050]

[0051] in , They are the minimum and maximum coupling coefficients respectively. Figure 2 is the output power-coupling coefficient of the detuned SS compensation topology curve.

[0052] The output power fluctuation range is defined as ;

[0053]

[0054] in , It is the maximum and minimum output power within the preset coupling coefficient range. , the system output power reaches the maximum value, that is .

[0055] make The derivative of is zero and solve ,Right now

[0056]

[0057] Substituting equation (14) into equation (10), we can get the maximum output power of the system: :

[0058]

[0059] according to In the curve , , The size relationship between the three is When equation (16) is satisfied, the fluctuation amplitude of the output power is minimal.

[0060]

[0061] Solving equation (16), we get the detuning rate :

[0062] According to the experimental parameters, the SS compensation topology with detuned transmitter and the full resonant SS compensation topology are The curve is as shown in the instruction manual. Figure 3 shown.

[0063] Attached to the instruction manual Figure 3 It can be seen that the output power within the preset coupling coefficient range is Meet the power fluctuation range However, the disadvantages of the detuning design can be clearly seen: although the detuning design at the transmitter does not affect the system efficiency, the presence of the reactance part in the input impedance reduces the effective value of the transmitter current, and the active part of the output power decreases accordingly, which will restrict the application of the detuning compensation strategy.

[0064] 2. Parameter design method of “reverse Г-type compensation network” at the transmitter

[0065] In order to solve the problem of low output power level in detuned design, an “inverse Г-type compensation network” is introduced at the transmitting end to increase the amplitude of the system equivalent power supply voltage and thus achieve an increase in the output power level.

[0066] In the instruction manual Figure 1Based on the detuned circuit shown in the figure, an “inverse Г-type compensation network” is introduced. To simplify the analysis, the entire receiving end circuit is equivalent to , forming an "improved LCC-S" circuit topology, as shown in the attached manual Figure 4 shown.

[0067] According to circuit theory, the instructions are attached Figure 4 The circuit shown is simplified equivalently. The simplified circuit is shown in the attached manual. Figure 5 shown.

[0068] In the equivalent simplification process, the following relationship holds true:

[0069]

[0070] in, is the equivalent power supply voltage, is the full-bridge inverter output voltage, is the system operating angular frequency, To compensate the network inductance, To compensate for network capacitance;

[0071] Let the adjustment variable:

[0072] From the above formula (1), we can get the inverter output voltage After equivalent transformation through the inverse Г-type compensation network, the amplitude is adjustable;

[0073] As the instruction manual Figure 5 In the simplest equivalent circuit shown, let and:

[0074] in, is the equivalent resistance, X is the reactance, is the equivalent power inductance, is the self-inductance of the transmitting coil, Compensation capacitor for the transmitter;

[0075] When reactance and resistance exist in a circuit at the same time, When the load power is the largest, the system input impedance angle is 45°. for The calculated reflected resistance is ; is the coupling coefficient, is the coupling coefficient when the system output power reaches the maximum;

[0076] Combining equations (1) to (3), we can get the maximum output power: for:

[0077]

[0078] From formula (4), we can get the adjustment variable Change the maximum output power, so by introducing the "reverse Г-type compensation network", it can not only compensate for the power drop caused by detuning compensation, but also achieve various output power requirements;

[0079] Based on the above derivation process, in order to compensate for the power drop caused by detuning compensation, the following equation is established:

[0080]

[0081] By using formula (5), the inductor in the “reverse Г-type compensation network” is configured. and capacitor parameter.

[0082] According to the duality phenomenon in the circuit, the instruction manual Figure 4 The "inverse Γ-type compensation network" shown can also be in the "CL" form.

[0083] Under the same DC power input conditions, the compensation topologies of “resonant SS”, “conventional LCC-S” and “improved LCC-S” The curve is as shown in the instruction manual. Figure 6 shown.

[0084] Attached to the instruction manual Figure 6 It can be seen that the "improved LCC-S" compensation topology based on the transmitter detuning design and the introduction of the "inverse Г-type compensation network" has an output power of Meet the 10% power fluctuation requirement and the best coupling coefficient The same power level as the full resonant SS compensation topology is achieved.

[0085] 3. Parameter design of "impedance inversion network" at the receiving end

[0086] The wireless power transmission system needs to have the ability to smoothly transmit power within a wide coupling coefficient range. After the transmitter is detuned and the "inverse Г-type compensation network" is introduced, the output power fluctuation range can only be met within a preset smaller coupling coefficient range. Therefore, in order to broaden the coupling coefficient variation range of the system's stable transmission power, an "impedance inversion network" is introduced between the receiving end compensation network and the load to transform the equivalent load resistance, forming an "improved LCC-CLC" circuit topology, as shown in the attached manual. Figure 7 shown.

[0087] The difference between “Improved LCC-S compensation topology” and “Improved LCC-CLC compensation topology” The curves should overlap at the end points of the set coupling coefficient interval, as shown in the attached manual. Figure 8 shown.

[0088] When the "impedance inversion network" is not introduced at the receiving end, the preset coupling coefficient is rewritten as When the "impedance inversion network" is introduced at the receiving end, The coupling coefficient interval on the left is set as , will be along The coupling coefficient interval on the right is set to , and satisfies

[0089]

[0090] Since the mutual inductance changes continuously,

[0091] Within the three coupling coefficient ranges, the output power fluctuation amplitude is the same, that is

[0092] Combined with formula (17), the equivalent resistance within the coupling coefficient range of each interval has the relationship of formula (21):

[0093]

[0094] Attached to the instruction manual Figure 8 It can be seen that the maximum output power in each coupling coefficient interval is equal, and the output power at the end points of the coupling coefficient interval is equal, that is:

[0095]

[0096] In the "impedance inverter network" of the "CLC" topology, the following conditions are met:

[0097] From equation (18) to equation (24), the parameters of inductor L and capacitor C in the “CLC” topology impedance inverter network are configured.

[0098] According to the duality phenomenon in the circuit, the instruction manual Figure 7 The "impedance inversion network" shown can also be in the form of "LCL", and the receiving end capacitor , inductor L can be equivalently combined into a dynamic element.

[0099] According to the star-delta transformation theory in circuit principles, the impedance inversion network of the "CLC" and "LCL" compensation topologies at the receiving end can perform star-delta equivalent transformation.

[0100] In order to distinguish the compensation network corresponding to each coupling coefficient interval, The impedance inverter network on the left is represented as "CLC2". The impedance inversion network on the right is represented by "CLC1".

[0101] Under the same DC power input condition, the compensation topologies of "Improved LCC-S", "Improved LCC-CLC2" and "Improved LCC-CLC1" are plotted in their respective coupling coefficient ranges. The curve is as shown in the instruction manual. Fig. 9 shown.

[0102] Attached to the instruction manual Fig. 9 It can be seen that when the coupling coefficient between the transmitter and the receiver varies in the range of (0.052, 0.1), (0.1, 0.192), and (0.192, 0.369), the maximum output power in each coupling coefficient interval is equal and the power fluctuation amplitude of each improved compensation topology is less than 10%, which verifies the effectiveness of the two compensation network parameter design methods.

[0103] IV. Experimental Verification

[0104] In order to verify the effectiveness of the two compensation network designs proposed in this invention to improve the compensation topology, a wireless power transmission anti-bias experimental platform was built. The transmitting and receiving coils adopt a circular structure, with an outer diameter of 11 cm, an inner diameter of 7 cm, 12 turns, and a Litz wire model of AWG38, 400 strands. The DC-AC inverter power supply is an inverter power supply with a bipolar square wave output and a rated power of 300w. The system circuit parameters are shown in Table 1 below.

[0105] Table 1 Circuit parameters

[0106]

[0107] The typical coupling coefficients of the compensation topologies of "Improved LCC-S", "Improved LCC-CLC2" and "Improved LCC-CLC1" The inverter outputs high-frequency voltage and current waveforms as shown in the attached manual. Fig.10 As shown, the typical coupling coefficient and the corresponding inverter output current peak , As shown in Table 2 and Table 3. The output voltage of the high-frequency inverter is a positive and negative square wave, but due to the influence of the on-resistance voltage drop of the switch tube, the amplitude of the positive and negative square waves is not a constant when they are positive and negative, and the voltage will drop.

[0108] Table 2 Typical coupling coefficients of three improved compensation topologies

[0109]

[0110] Table 3 Inverter output current peak

[0111]

[0112] From the instruction manual Fig.10 It can be found that the inverter output current lags behind the inverter output voltage, that is, the inverter switch tube meets the soft switching condition, which is beneficial to reduce power loss. Fig.11 is the system output power measured within each coupling coefficient range.

[0113] Attached to the instruction manual Fig.11 It can be seen that the actual coupling ranges of the compensation topologies of "Improved LCC-CLC2", "Improved LCC-S" and "Improved LCC-CLC1" that meet the 10% power fluctuation level are (0.055, 0.097), (0.114, 0.189) and (0.206, 0.362), which have good anti-offset characteristics. Due to the parasitic resistance introduced by the high-frequency effect of the inductor and capacitor components, the loss resistance of the inverter switch tube and other factors, the actual coupling coefficient range deviates from the set range, and causes discontinuity between the three coupling coefficients.

[0114] Instructions attached Fig.12 It is the efficiency characteristic curve in each coupling coefficient range, which is the overall system efficiency from the DC power supply to the receiving end load. It can be seen from the figure that within the output power fluctuation range of 10%, the efficiency of the system is always higher than 72%, and the "improved LCC-CLC2 (CLC1)" compensation topology uses the largest number of dynamic components, and its efficiency is significantly lower than that of the "improved LCC-S" compensation topology.

[0115] In summary, the experimental results show the effectiveness of the two compensation network designs of the present invention to improve the compensation topology. In the coupling coefficient range of (0.055, 0.097), (0.114, 0.189), and (0.206, 0.362), the output power fluctuation is less than 10%, and the system energy transmission efficiency is higher than 72%.

[0116] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A design method for a double-terminal compensation network of a WPT system with strong anti-bias, characterized in that: The following steps are involved: Step 1: Establish a wireless power transmission system based on the SS compensation topology and perform a detuning analysis on the output power of the transmitter; Step 2: Introduce an inverse Г-type compensation network into the detuned transmitting end of the wireless power transmission system established in step 1, and use the reflection impedance theory to represent the entire receiving end circuit equivalently, forming an improved LCC-S circuit topology, and then simplify the circuit equivalently according to the circuit theory; In the equivalent simplification process, the following relationship holds true in, is the equivalent power supply voltage, is the full-bridge inverter output voltage, is the system operating angular frequency, To compensate the network inductance, To compensate for network capacitance; Let the adjustment variable n From the above formula (1), we can get the inverter output voltage After equivalent transformation by the inverse Г-type compensation network, the voltage amplitude at the transmitting end can be adjusted; In the equivalent simplified circuit, let and: in, is the equivalent resistance, is the reactance, is the equivalent power inductance, is the self-inductance of the transmitting coil, Compensation capacitor for the transmitter; When reactance and resistance exist in a circuit at the same time, When the load power is the largest, the system input impedance angle is 45°. for The calculated reflected resistance is ; is the coupling coefficient, is the coupling coefficient when the system output power reaches the maximum; Combining equations (1)-(3) we can get the maximum output power: for From formula (4), we can get the adjustment variable Make changes to the maximum output power; Based on the above derivation process, the following equation is established By configuring the inductor in formula (5) and capacitor Parameters compensate for the power drop caused by detuning compensation; Step 3: On the basis of introducing an inverse Г-type compensation network at the transmitting end, an impedance inversion network is introduced between the compensation network and the load at the receiving end of the wireless power transmission system to transform the equivalent load resistance, thereby forming an improved LCC-CLC circuit topology and completing the double-end design of the wireless power transmission system; The connection relationship of the wireless power transmission system after the introduction of the inverse Г-type compensation network at the transmitting end and the impedance inversion network at the receiving end is as follows: After connecting to the inverse Г-type compensation network and the capacitor and inductance Connect in series to form the transmitter; inductor With capacitor After connecting in series, connect to the impedance inverter network, and then connect the load in series The receiving end is composed of the impedance inversion network: The T-shaped structure Series connection.

Images