Asymmetric coupling type multi-frequency wireless power transmission wide range voltage equalization control method

Abstract

The application discloses an asymmetric coupling type multi-frequency wireless power transmission wide-range voltage equalization control method and belongs to the field of wireless power transmission. Based on asymmetric mutual inductance wireless connection between a transmitting end and three loads connected with receiving ends, and connection of a transmitting coil with a direct current power supply in the transmitting end through an inverter, a load voltage closed-loop control is designed, multi-frequency SPWM wave modulation degree control is adopted, and receiving coil dynamic offset control is combined, so that balanced and stable voltage is provided for three-phase loads; under the premise of efficient energy transmission, the load voltage adjustable range of the voltage equalization output system is widened under the condition of fixed load, and the variable range of each phase load is widened under the condition of fixed load voltage reference, so that the application is suitable for voltage equalization control of a multi-frequency multi-load wireless power transmission system under the condition of variable load. The application has wide application prospect and is suitable for intelligent charging of multiple portable devices, dynamic charging of electric vehicles, wireless motor driving and the like.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, specifically relating to a wide-range voltage equalization control method for asymmetric coupled multi-frequency wireless power transmission. Background Technology

[0002] Wireless power transfer (WPT) transmits electrical energy directly to the load through space without the need for wires or other physical connections, offering advantages such as flexible and convenient power transmission. With the development of WPT technology, its research and application have gradually expanded from the traditional single-load power supply mode to multi-load power supply modes.

[0003] Multi-load WPT systems can be divided into single-frequency multi-load systems and multi-frequency multi-load systems. Single-frequency multi-load WPT systems employ decoupled coil designs or add a DC-DC converter at the receiver to achieve independent control of each load, but they struggle to power loads with different resonant frequencies. Multi-frequency multi-load WPT systems operate at different frequencies according to requirements, thus constructing multi-frequency energy transmission channels and achieving decoupled control of multi-load output power, avoiding additional power losses caused by the internal resistance of multiple transmitting coils and the DC-DC converter. Simultaneously, to reduce or eliminate crosstalk caused by non-target resonant frequencies, auxiliary circuitry is typically added at the receiver to suppress the negative impact of crosstalk in a three-load system.

[0004] In practical applications, system loads often change continuously with operating conditions, such as battery, LED light, and motor loads. For multi-frequency, multi-load systems, since each load operates at a different frequency, it is difficult to maintain equal voltage output under varying load conditions. Therefore, basic load voltage closed-loop control is essential. However, the upper limit of equal voltage output for multiple loads depends on the load with the smallest upper voltage output, which inevitably leads to premature saturation of the inverter's output voltage amplitude adjustment. Consequently, traditional control suffers from a narrow adjustable range for equal voltage output and a narrow variable range for the load under rated voltage reference. Summary of the Invention

[0005] The technical problem to be solved by this invention is that the upper limit of the voltage equalization output of multiple loads depends on the one with the smallest upper limit of voltage output among the loads, which will inevitably lead to the premature saturation of the inverter output voltage amplitude adjustment. Therefore, traditional control has the problem of narrow adjustable range of voltage equalization output and narrow variable range of load under rated voltage reference.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A wide-range voltage equalization control method for asymmetric coupled multi-frequency wireless power transmission is disclosed. This method is based on a wireless power transmission system with asymmetric coil mutual inductance wireless connection between the transmitter and three loads connected to the receiver. The DC power supply in the transmitter is connected to the transmitting coil via an inverter. The inverter includes two parallel bridge arms. The first bridge arm includes an upper bridge arm switch Q1 and a lower bridge arm switch Q2 connected in series. The second bridge arm includes an upper bridge arm switch Q3 and a lower bridge arm switch Q4 connected in series. The three loads are connected to receivers A, B, and C, respectively. The following steps are performed to achieve voltage control of the three loads.

[0008] Step A1: Collect the actual voltage u corresponding to the three loads respectively. LA u LB u LC and the operating frequencies f corresponding to the three loads respectively. A f B f C and obtain u LA u LB u LC With preset reference voltage u ref Find the difference between them, and then proceed to step A2;

[0009] Step A2: For u respectively LA u LB u LC With preset reference voltage u ref The difference between them is PI-regulated to obtain the SPWM modulation level a corresponding to phases A, B, and C respectively. rA a rB a rC Then proceed to step A3;

[0010] Step A3: For a respectively rA a rB a rC Amplitude limiting is applied, with the limiting range set to [0, a]. rth If a rA a rB a rC None of them are greater than the preset modulation threshold a rth Adjustment system a rA a rB a rC Keeping the voltage unchanged, proceed to steps A4 and A5 to adjust the voltages corresponding to the three loads to the preset reference voltage u. ref This enables voltage control of three loads; if there exists a rm Greater than the preset modulation threshold a rth Execute step A6 to adjust the m-phase modulation regime a rm Limit to a rthThen, perform steps A4 to A5 to adjust the voltages corresponding to the three loads to the preset reference voltage u. ref This enables voltage control of three loads; where m represents the receiving end, m = A represents receiving end A, m = B represents receiving end B, and m = C represents receiving end C.

[0011] Step A4: Adjust the modulation a rA With sin(2πf) A t) multiplication, a rB With sin(2πf) B t) multiplication, a rC With sin(2πf) C Multiply by t) to obtain the modulation waves a corresponding to phases A, B, and C respectively. rA sin(2πf A t), a rB sin(2πf B t), a rC sin(2πf C t);

[0012] Step A5: Drive switches Q1 and Q4 based on the multi-frequency SPWM control signal obtained by subtracting the sum of the modulation waves of phases A, B, and C from the preset carrier wave; drive switches Q2 and Q3 based on the multi-frequency SPWM control signal obtained by subtracting the sum of the modulation waves of phases A, B, and C from the preset carrier wave and then inverting it; so that the voltages corresponding to the three loads reach the preset reference voltage u. ref This enables voltage control of three loads;

[0013] Step A6: Start the m-phase receiving coil offset adjustment, targeting the corresponding a for m. rm With a rth The difference is adjusted using a PI controller to obtain the offset of the m-phase receiving coil.

[0014] As a preferred embodiment of the present invention, the m-phase receiving coil offset adjustment includes longitudinal offset adjustment, lateral offset adjustment, and angular offset adjustment.

[0015] As a preferred embodiment of the present invention, in step A6, the offset of the m-phase receiving coil is obtained through the following steps:

[0016] When the m-phase receiving coil offset adjustment is set to longitudinal offset adjustment, for m-phase a rm With a rth The difference is used for PI adjustment, combined with limiting the adjustment range [h] ma h mb ], obtain the longitudinal offset h of the m-phase receiving coil m ;

[0017] When the m-phase receiving coil offset adjustment is set to lateral offset adjustment, for m-phase a rm With a rth The difference is used for PI adjustment, combined with limiting the adjustment range [Δ]. ma Δ mb ], obtain the lateral offset Δ of the m-phase receiving coil m ;

[0018] When the m-phase receiving coil offset adjustment is set to angle offset adjustment, for m-phase a rm With a rth The difference is used for PI adjustment, combined with limiting the adjustment range [α]. ma α mb ], obtain the angular offset α of the m-phase receiving coil. m .

[0019] As a preferred embodiment of the present invention, the limiting adjustment ranges of the m-phase longitudinal offset adjustment, lateral offset adjustment, and angular offset adjustment are specifically obtained through the following steps:

[0020] Step B1: Obtain the outer diameter r of the transmitting coil To Number of turns N T Turn spacing p, internal resistance R T Obtain the outer diameter r of the m-phase receiving coil mo Number of turns N m , turn spacing p m Internal resistance R m Furthermore, the outer diameters of the receiving coils in phases A, B, and C are the same, i.e.: r Ao =r Bo =r Co Then proceed to step B2;

[0021] Step B2: Obtain the initial longitudinal offset h0, initial lateral offset Δ0, and initial angular offset α0 of the receiving coils of phases A, B, and C relative to the transmitting coil, and then proceed to step B3;

[0022] Step B3: Based on the preset transmission efficiency threshold η of the wireless power transmission system th m-phase load resistance R Lm The operating frequency f corresponding to the m-phase load m The minimum adjustable mutual inductance M between the m-phase receiving coil and transmitting coil is obtained according to the following formula. Tma Proceed to step B4:

[0023]

[0024] Step B4: The adjustment range for the longitudinal offset adjustment of phase m is obtained through steps B5-B6; the adjustment range for the lateral offset adjustment of phase m is obtained through steps B7-B8; the adjustment range for the angular offset adjustment of phase m is obtained through steps B9-B10.

[0025] Step B5: Obtain the radius r of the i-th turn of the transmitting coil according to the following formula. Ti The radius r of the j-th turn of the receiving coil mj :

[0026]

[0027] In this case, the turn spacing between the transmitting coil and the receiving coil is the same, that is: p = p m ;

[0028] Furthermore, based on the initial lateral offset Δ0 of phase m, the initial angular offset α0, and the minimum adjustable mutual inductance M between the phase m receiving coil and transmitting coil... Tma The upper limit h of the longitudinal offset adjustment range of phase m is obtained according to the following formula. mb :

[0029]

[0030] Where μ0 represents the free permeability; θ is the angle between the x-axis and the length vector of the transmitting coil in the coordinate system corresponding to the transmitting coil. It is the angle between the x' axis and the length vector of the receiving coil in the coordinate system corresponding to the m-phase receiving coil, where x represents the unit vector (1, 0, 0), y represents the unit vector (0, 1, 0), and z represents the unit vector (0, 0, 1). Then proceed to step B6.

[0031] Step B6: Based on the distance between the m-phase receiving coil and the transmitting coil, obtain the lower limit h of the longitudinal offset adjustment range of the receiving coil. ma Thus, the limiting adjustment range of the m-phase longitudinal offset adjustment [h] is obtained. ma h mb ];

[0032] Step B7: Based on the initial longitudinal offset h0 of phase m, the initial angular offset α0, and the minimum adjustable mutual inductance M between the phase m receiving coil and transmitting coil. Tma The upper limit Δ of the lateral offset adjustment range of phase m is obtained according to the following formula. mb Then proceed to step B8;

[0033]

[0034] Step B8: Obtain the lower limit Δ of the lateral offset adjustment range of the receiving coil according to the following formula. maThus, the limiting adjustment range of the m-phase longitudinal offset adjustment [Δ] is obtained. ma Δ mb ]:

[0035]

[0036] Step B9: Based on the initial longitudinal offset h0 of phase m, the initial lateral offset Δ0, and the minimum adjustable mutual inductance M between the phase m receiving coil and transmitting coil. Tma The upper limit α of the lateral offset adjustment range of phase m is obtained according to the following formula. mb Then proceed to step B10:

[0037]

[0038] Step B10: Lower limit α of the receiving coil angle offset adjustment range ma Setting it to 0, we obtain the limiting adjustment range [α] for the m-phase angle offset adjustment. ma α mb ].

[0039] A topology based on the aforementioned asymmetric coupled multi-frequency wireless power transfer wide-range voltage equalization control method is characterized by: including a transmitter, receiver A, receiver B, and receiver C, wherein the transmitter and the three receivers are wirelessly connected via asymmetric coil mutual inductance; the transmitter includes a DC power supply V. in Inverter, DC-side filter capacitor C r Compensation network, internal resistance R of transmitting coil T The inductance of the transmitting coil L T The inverter includes two parallel bridge arms. The first bridge arm includes an upper bridge arm switch Q1 and a lower bridge arm switch Q2 connected in series. The second bridge arm includes an upper bridge arm switch Q3 and a lower bridge arm switch Q4 connected in series. The compensation network is an LCC high-order compensation network, including an LCC series inductor L. p LCC parallel compensation capacitor C P , transmitting coil compensation capacitor C T ;

[0040] DC power supply V in One end is connected to the DC-side filter capacitor C. r One end of the circuit, the drain of switching transistor Q1 and the drain of switching transistor Q3, DC power supply V in The other end is connected to the DC-side filter capacitor C. r The other end, the source of switch Q2 and the source of switch Q4; the source of switch Q1, the drain of switch Q2, and the LCC series inductor L. p One end of the three components is connected in parallel; the source of switching transistor Q3, the drain of switching transistor Q4, and the LCC are connected in parallel with the compensation capacitor C. POne end of the transmitting coil, internal resistance R T One end of the four components is connected in series; LCC series inductor L p At the other end, LCC is connected in parallel with compensation capacitor C. P At the other end, the transmitting coil compensation capacitor C T One end of the three components is connected in parallel; the transmitting coil compensation capacitor C T The other end is connected to the transmitting coil inductance L T One end of the transmitting coil is connected to the other end; the internal resistance R of the transmitting coil is... T The other end is connected to the transmitting coil inductance L T The other end is connected;

[0041] Receiver A, Receiver B, and Receiver C have the same structure. The structure of each receiver is as follows: it includes a receiving coil and an inductor L. m The internal resistance R of the receiving coil m Receiver filter capacitor C mf rectifier and load resistor R Lm ;

[0042] Receiver coil inductance L m One end of the receiver coil is connected to one end of the AC side of the rectifier; the receiving coil inductance L m The other end is connected to the internal resistance R of the receiving coil. m One end is connected; the internal resistance R of the receiving coil m The other end is connected to the other end of the AC side of the rectifier; one end of the DC side of the rectifier, the receiving end filter capacitor C mf One end, load resistor R Lm One end of the three components is connected in parallel; the other end of the rectifier's DC side and the receiving end filter capacitor C mf The other end, load resistor R Lm The other end of the three are connected.

[0043] As a preferred embodiment of the present invention, the receiving end further includes an S-type compensation network and a blocking network; the receiving coil inductance L m One end of the circuit is sequentially connected to one end of the rectifier's AC side via a blocking network and an S-type compensation network; the blocking network includes a blocking network inductor L. m1 Blocking network inductor L m2 Blocking network compensation capacitor C m1 Blocking network compensation capacitor C m2 The S-type compensation network includes a receiving coil compensation capacitor C. m ; Receiver coil inductance L m One end of the blocking network inductor L m1 One end of the blocking network compensation capacitor C m1One end of the three components is connected to the other; blocking network inductor L m1 The other end, the blocking network compensation capacitor C m1 The other end, blocking network inductor L m2 One end of the blocking network compensation capacitor C m2 One end of the four components is connected to each other; blocking network inductor L m2 The other end, the blocking network compensation capacitor C m2 The other end, receiving coil compensation capacitor C m One end of the three components is connected in parallel; the receiving coil compensation capacitor C m The other end is connected to one end of the AC side of the rectifier.

[0044] The beneficial effects of this invention are as follows: This invention proposes an asymmetric coupled multi-frequency wireless power transmission wide-range voltage equalization control method; based on the asymmetric coil mutual inductance wireless connection between the transmitter and the three loads connected to the receiver, and the DC power supply in the transmitter connected to the transmitting coil via an inverter, the design employs load voltage closed-loop control, based on multi-frequency SPWM waveform modulation control, combined with receiving coil dynamic offset control, including longitudinal offset control, lateral offset control, and angular offset control, thereby providing a balanced and stable voltage for the three-phase loads; with efficient energy transmission as a prerequisite, under constant load conditions, it widens the adjustable range of the load voltage of the voltage equalization output system, and under constant load voltage reference conditions, it widens the variable range of each phase load, applicable to voltage equalization control of multi-frequency multi-load wireless power transmission systems under variable load conditions. This invention has broad application prospects, including intelligent charging of multiple portable devices, dynamic charging of electric vehicles, and wireless motor drive, etc. Attached Figure Description

[0045] Figure 1 This invention includes a multi-frequency, multi-load wireless power transmission topology, a wide-range voltage equalization control block diagram for wireless power transmission, and an asymmetric coupling structure.

[0046] Figure 2 This invention provides a comparison of the load voltage regulation range under asymmetric and symmetric coupling conditions in the embodiments of the present invention.

[0047] Figure 3 This is a curve showing the change of load voltage with load resistance under symmetrical coupling conditions in an embodiment of the present invention;

[0048] Figure 4 This is a curve showing the change of load voltage with load resistance under asymmetric coupling conditions in an embodiment of the present invention. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings. The following embodiments will enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way.

[0050] like Figure 1 As shown in Figure (a), this scheme designs a topology based on an asymmetric coupled multi-frequency wireless power transmission wide-range voltage equalization control method, including a transmitter, receiver A, receiver B, and receiver C. The transmitter and the three receivers are wirelessly connected by asymmetric coil mutual inductance, so the mutual inductance between the transmitter coil and the multiple receiver coils is different, i.e., the so-called asymmetric coil mutual inductance wireless connection; the transmitter includes a DC power supply V. in Inverter, DC-side filter capacitor C r Compensation network, internal resistance R of transmitting coil T The inductance of the transmitting coil L T The inverter includes two parallel bridge arms. The first bridge arm includes an upper bridge arm switch Q1 and a lower bridge arm switch Q2 connected in series. The second bridge arm includes an upper bridge arm switch Q3 and a lower bridge arm switch Q4 connected in series. The compensation network is an LCC high-order compensation network, including an LCC series inductor L. p LCC parallel compensation capacitor C P , transmitting coil compensation capacitor C T .

[0051] DC power supply V in One end is connected to the DC-side filter capacitor C. r One end of the circuit, the drain of switching transistor Q1 and the drain of switching transistor Q3, DC power supply V in The other end is connected to the DC-side filter capacitor C. r The other end, the source of switch Q2 and the source of switch Q4; the source of switch Q1, the drain of switch Q2, and the LCC series inductor L. p One end of the three components is connected in parallel; the source of switching transistor Q3, the drain of switching transistor Q4, and the LCC are connected in parallel with the compensation capacitor C. P One end of the transmitting coil, internal resistance R T One end of the four components is connected in series; LCC series inductor L p At the other end, LCC is connected in parallel with compensation capacitor C. P At the other end, the transmitting coil compensation capacitor C T One end of the three components is connected in parallel; the transmitting coil compensation capacitor C T The other end is connected to the transmitting coil inductance L T One end of the transmitting coil is connected to the other end; the internal resistance R of the transmitting coil is... T The other end is connected to the transmitting coil inductance L T The other end is connected.

[0052] Receiver A, Receiver B, and Receiver C have the same structure. The structure of each receiver is as follows: it includes a receiving coil and an inductor L. m The internal resistance R of the receiving coil mReceiver filter capacitor C mf rectifier and load resistor R Lm ; Receiver coil inductance L m One end of the receiver coil is connected to one end of the AC side of the rectifier; the receiving coil inductance L m The other end is connected to the internal resistance R of the receiving coil. m One end is connected; the internal resistance R of the receiving coil m The other end is connected to the other end of the AC side of the rectifier; one end of the DC side of the rectifier, the receiving end filter capacitor C mf One end, load resistor R Lm One end of the three components is connected in parallel; the other end of the rectifier's DC side and the receiving end filter capacitor C mf The other end, load resistor R Lm The other end of the three are connected.

[0053] The topology is specifically a multi-frequency, multi-load wireless power transmission topology with a blocking network. Furthermore, the receiving end also includes an S-type compensation network and a blocking network; the receiving coil inductance L... m One end of the circuit is sequentially connected to one end of the rectifier's AC side via a blocking network and an S-type compensation network; the blocking network includes a blocking network inductor L. m1 Blocking network inductor L m2 Blocking network compensation capacitor C m1 Blocking network compensation capacitor C m2 The S-type compensation network includes a receiving coil compensation capacitor C. m ; Receiver coil inductance L m One end of the blocking network inductor L m1 One end of the blocking network compensation capacitor C m1 One end of the three components is connected to the other; blocking network inductor L m1 The other end, the blocking network compensation capacitor C m1 The other end, blocking network inductor L m2 One end of the blocking network compensation capacitor C m2 One end of the four components is connected to each other; blocking network inductor L m2 The other end, the blocking network compensation capacitor C m2 The other end, receiving coil compensation capacitor C m One end of the three components is connected in parallel; the receiving coil compensation capacitor C m The other end is connected to one end of the AC side of the rectifier.

[0054] Figure 1 In the middle, V in C is the DC power supply voltage. r For DC-side filter capacitors; u Si is the AC output voltage of the primary-side inverter; S L is the AC output current of the primary-side inverter. p For LCC series inductor; L T C is the inductance of the transmitting coil. P For LCC parallel compensation capacitor; C T For compensating the transmitting coil; R T M is the internal resistance of the transmitting coil; Tm (m = A, B, C) represents the mutual inductance between the transmitting coil and the receiving coil, i.e., the mutual inductance between the transmitting coil and the receiving coil at the receiving end; M mk (k = A, B, C, m ≠ k) represents the mutual inductance between the receiving coils, i.e., the mutual inductance between the receiving coil at receiving end m and the receiving coil at receiving end k; L m For the receiving end m, the inductance of the receiving coil is; C m For the receiving coil compensation capacitor at the receiving end m; L m1 ~L m2 For the receiving end m, the blocking network inductance; C m1 ~C m2 For the receiver m-blocking network compensation capacitor; R m The internal resistance of the receiving coil at the receiving end m; u m The voltage on the AC side of the rectifier at the receiving end m; i m For the AC side current of the rectifier at the receiving end m; i Lm The receiver's load current is m; u Lm C is the load voltage at the receiving end m; mf For the receiving end, m is the filter capacitor; R Lm Let m be the load resistance at the receiving end.

[0055] like Figure 1 As shown in Figure (b), this is a block diagram for a wide-range voltage equalization control of asymmetric coupled multi-frequency multi-load wireless power transmission based on the above topology. Specifically, it is a wide-range voltage equalization control method for asymmetric coupled multi-frequency wireless power transmission, based on a wireless power transmission system with asymmetric coil mutual inductance wireless connection between the transmitter and the receivers connected to the three loads. The DC power supply in the transmitter is connected to the transmitter coil via an inverter. The inverter includes two parallel bridge arms. The first bridge arm includes an upper bridge arm switch Q1 and a lower bridge arm switch Q2 connected in series. The second bridge arm includes an upper bridge arm switch Q3 and a lower bridge arm switch Q4 connected in series. The receivers connected to the three loads are receiver A, receiver B, and receiver C, respectively. The control method includes a wide-range voltage equalization control method for asymmetric coupled multi-frequency multi-load wireless power transmission, which specifically executes the following steps to achieve voltage control of the three loads.

[0056] Step A1: Collect the actual voltage u corresponding to the three loads respectively. LA u LB uLC and the operating frequencies f corresponding to the three loads respectively. A f B f C and obtain u LA u LB u LC With preset reference voltage u ref Find the difference between them, and then proceed to step A2;

[0057] Step A2: For u respectively LA u LB u LC With preset reference voltage u ref The difference between them is PI-regulated to obtain the SPWM modulation level a corresponding to phases A, B, and C respectively. rA a rB a rC Then proceed to step A3;

[0058] Step A3: For a respectively rA a rB a rC Amplitude limiting is applied, with the limiting range set to [0, a]. rth If a rA a rB a rC None of them are greater than the preset modulation threshold a rth Adjustment system a rA a rB a rC Keeping the voltage unchanged, proceed to steps A4 and A5 to adjust the voltages corresponding to the three loads to the preset reference voltage u. ref This enables voltage control of three loads; if there exists a rm Greater than the preset modulation threshold a rth Execute step A6 to adjust the m-phase modulation regime a rm Limit to a rth Then, perform steps A4 to A5 to adjust the voltages corresponding to the three loads to the preset reference voltage u. ref This enables voltage control of three loads; where m represents the receiving end, m = A represents receiving end A, m = B represents receiving end B, and m = C represents receiving end C.

[0059] Step A4: Adjust the modulation level a rA With sin(2πf) A t) multiplication, a rB With sin(2πf) B t) multiplication, a rC With sin(2πf) C Multiply by t) to obtain the modulation waves a corresponding to phases A, B, and C respectively.rA sin(2πf A t), a rB sin(2πf B t), a rC sin(2πf C t);

[0060] Step A5: Drive switches Q1 and Q4 based on the multi-frequency SPWM control signal obtained by subtracting the sum of the modulation waves of phases A, B, and C from the preset carrier wave; drive switches Q2 and Q3 based on the multi-frequency SPWM control signal obtained by subtracting the sum of the modulation waves of phases A, B, and C from the preset carrier wave and then inverting it; so that the voltages corresponding to the three loads reach the preset reference voltage u. ref This enables voltage control of three loads; the preset carrier is a centrally symmetrical triangular carrier with amplitudes of 1 and -1.

[0061] Step A6: Start the m-phase receiving coil offset adjustment, targeting m-phase a rm With a rth The difference is PI-adjusted to obtain the offset of the m-phase receiving coil. That is, when a rm >a rth This indicates that the m-phase SPWM waveform modulation control is saturated, and it is necessary to activate the m-phase offset adjustment to adjust the mutual inductance M between the m-phase receiving coil and the transmitting coil. Tm .

[0062] The m-phase receiving coil offset adjustment includes longitudinal offset adjustment, lateral offset adjustment, and angular offset adjustment. That is, by selecting any offset adjustment, changing the longitudinal, lateral, or angular offset of the receiving coil, the mutual inductance between the transmitting and receiving coils is altered. This expands the multi-load voltage equalization control range and increases the load variability while maintaining efficient energy transmission. In this scheme, phases A, B, and C correspond to receiving terminals A, B, and C, respectively. Furthermore, the offset in this scheme refers to the offset of the receiving coil relative to the transmitting coil, based on the coordinate system corresponding to the transmitting coil, with the center of the transmitting coil as the origin, any direction on the plane containing the transmitting coil as the x-axis, and the direction perpendicular to the plane containing the transmitting coil... If the direction of the plane is the z-axis, and the direction perpendicular to the x-axis in the plane containing the transmitting coil is the y-axis, then the longitudinal offset of the m-phase receiving coil is the distance along the z-axis between the center of the m-phase receiving coil and the center of the transmitting coil in the transmitting coil coordinate system. The lateral offset of the m-phase receiving coil is the distance along the x-axis between the center of the m-phase receiving coil and the center of the transmitting coil in the transmitting coil coordinate system. The angular offset of the m-phase receiving coil is the spatial angle in the transmitting coil coordinate system between the straight line passing through the center of the transmitting coil and perpendicular to the plane containing the transmitting coil, and the straight line passing through the center of the m-phase receiving coil and perpendicular to the plane containing the m-phase receiving coil. During the adjustment of the m-phase receiving coil offset, if adjusting the position of the receiving coil cannot bring the voltage corresponding to the three loads to the preset reference voltage u...ref Then the parameters of the topology system of this scheme will be redesigned. The offset of the m-phase receiving coil is obtained through the following steps:

[0063] When the m-phase receiving coil offset adjustment is set to longitudinal offset adjustment, for m-phase a rm With a rth The difference is used for PI adjustment, combined with limiting the adjustment range [h] ma h mb ], obtain the longitudinal offset h of the m-phase receiving coil m ;

[0064] When the m-phase receiving coil offset adjustment is set to lateral offset adjustment, for m-phase a rm With a rth The difference is used for PI adjustment, combined with limiting the adjustment range [Δ]. ma Δ mb ], obtain the lateral offset Δ of the m-phase receiving coil m ;

[0065] When the m-phase receiving coil offset adjustment is set to angle offset adjustment, for m-phase a rm With a rth The difference is used for PI adjustment, combined with limiting the adjustment range [α]. ma α mb ], obtain the angular offset α of the m-phase receiving coil. m .

[0066] The adjustment ranges for the m-phase longitudinal offset, lateral offset, and angular offset are based on the system transmission efficiency threshold η in practical applications. th Regarding space placement limitations, the specific steps are as follows:

[0067] Step B1: Obtain the outer diameter r of the transmitting coil To Number of turns N T Turn spacing p, internal resistance R T Obtain the outer diameter r of the m-phase receiving coil mo Number of turns N m , turn spacing p m Internal resistance R m Furthermore, the outer diameters of the receiving coils in phases A, B, and C are the same, i.e.: r Ao =r Bo =r Co Asymmetric coupling structures, such as Figure 1 As shown in (c), the asymmetric magnetic coupling mechanism is a magnetic coupling mechanism in which the longitudinal offset, lateral offset, and angular offset of the multiple receiving coils are not completely the same. In contrast, the traditional symmetric magnetic coupling mechanism is a magnetic coupling mechanism in which the longitudinal offset, lateral offset, and angular offset of the multiple receiving coils are completely the same. Then proceed to step B2;

[0068] Step B2: Obtain the initial longitudinal offset h0, initial lateral offset Δ0, and initial angular offset α0 of the receiving coils of phases A, B, and C relative to the transmitting coil, and then proceed to step B3;

[0069] Step B3: Based on the preset transmission efficiency threshold η of the wireless power transmission system th m-phase load resistance R Lm The operating frequency f corresponding to the m-phase load m The minimum adjustable mutual inductance M between the m-phase receiving coil and transmitting coil is obtained according to the following formula. Tma Proceed to step B4:

[0070]

[0071] Step B4: The adjustment range for the longitudinal offset adjustment of phase m is obtained through steps B5-B6; the adjustment range for the lateral offset adjustment of phase m is obtained through steps B7-B8; the adjustment range for the angular offset adjustment of phase m is obtained through steps B9-B10.

[0072] Step B5: Obtain the radius r of the i-th turn of the transmitting coil according to the following formula. Ti The radius r of the j-th turn of the receiving coil mj :

[0073]

[0074] In this case, the turn spacing between the transmitting coil and the receiving coil is the same, that is: p = p m ;

[0075] Furthermore, based on the initial lateral offset Δ0 of phase m, the initial angular offset α0, and the minimum adjustable mutual inductance M between the phase m receiving coil and transmitting coil... Tma The upper limit h of the longitudinal offset adjustment range of phase m is obtained according to the following formula. mb :

[0076]

[0077] Where μ0 represents the free permeability; θ is the angle between the x-axis and the length vector of the transmitting coil in the coordinate system corresponding to the transmitting coil. This is the angle between the x' axis (x-axis) and the length vector of the receiving coil in the coordinate system corresponding to the m-phase receiving coil, where x represents the unit vector (1, 0, 0), y represents the unit vector (0, 1, 0), and z represents the unit vector (0, 0, 1). Then proceed to step B6; as... Figure 1As shown in (C), the coordinate system corresponding to the transmitting coil is with the center of the transmitting coil as the origin, any direction in the plane where the transmitting coil is located as the x-axis, the direction perpendicular to the plane where the transmitting coil is located as the z-axis, and the direction perpendicular to the x-axis in the plane where the transmitting coil is located as the y-axis; the coordinate system corresponding to the receiving coil is the coordinate system obtained after transforming the coordinate system corresponding to the transmitting coil by the initial longitudinal offset h0, the initial lateral offset Δ0, and the initial angular offset α0, with the center of the receiving coil as the origin.

[0078] Step B6: Based on the coil spacing limit, i.e., based on the spacing between the m-phase receiving coil and the transmitting coil, obtain the lower limit h of the longitudinal offset adjustment range of the receiving coil. ma Thus, the limiting adjustment range of the m-phase longitudinal offset adjustment [h] is obtained. ma h mb ];

[0079] Step B7: Based on the initial longitudinal offset h0 of phase m, the initial angular offset α0, and the minimum adjustable mutual inductance M between the phase m receiving coil and transmitting coil. Tma The upper limit Δ of the lateral offset adjustment range of phase m is obtained according to the following formula. mb Then proceed to step B8;

[0080]

[0081] Step B8: Based on the geometric position constraints of the multi-coil system, obtain the lower limit Δ of the lateral offset adjustment range of the receiving coil according to the following formula. ma Thus, the limiting adjustment range of the m-phase longitudinal offset adjustment [Δ] is obtained. ma Δ mb ]:

[0082]

[0083] Step B9: Based on the initial longitudinal offset h0 of phase m, the initial lateral offset Δ0, and the minimum adjustable mutual inductance M between the phase m receiving coil and transmitting coil. Tma The upper limit α of the lateral offset adjustment range of phase m is obtained according to the following formula. mb Then proceed to step B10:

[0084]

[0085] Step B10: Lower limit α of the receiving coil angle offset adjustment range ma Setting it to 0, we obtain the limiting adjustment range [α] for the m-phase angle offset adjustment. ma α mb ].

[0086] like Figure 2The figure shows a comparison of the load voltage regulation range under asymmetrical and symmetrical coupling conditions. Based on R... Lm =R0, based on the system transmission efficiency threshold η th The lower limit M of the three mutual induction regulation can be obtained. Tma (m = A, B, C), adjust the lower limit h of the longitudinal offset range of the receiving coil. ma Horizontal offset adjustment range lower limit Δ ma , Lower limit of angle offset adjustment range α ma The upper limit of the three-way mutual induction adjustment M can be obtained. Tmb .

[0087] Under the initial position conditions, i.e., when the receiving coils of phases A, B, and C are offset in the same way (i.e., longitudinal offset h0, lateral offset Δ0, and angular offset α0), the mutual inductance value M can be calculated. TA =M TB =M TC =M0, using traditional symmetrical coupling condition load voltage closed-loop control to obtain the load voltage regulation range under symmetrical coupling conditions; using asymmetrical coupling multi-frequency multi-load wireless power transmission wide-range voltage equalization control, after dynamic offset adjustment of the receiving coil, M TA =M TB =M0, M TC =M1, the load voltage regulation range increases significantly.

[0088] like Figure 3 The figure shows the curve of load voltage versus load resistance under symmetrical coupling conditions, where the mutual inductance M between the three-phase receiving coil and transmitting coil is... TA =M TB =M TC =M0, when R Lm When R = 0, the load voltage of phases A and B is U. ref C-phase load voltage U LC ref Based on the voltage equalization control requirement, namely: the upper limit of voltage equalization control is the minimum upper limit of the three-phase load voltage, it can be known that the adjustable range of the load voltage is [0, U]. LC ].

[0089] like Figure 4 The figure shows the load voltage variation curve with load resistance under asymmetrical coupling conditions. After dynamic offset adjustment of the receiving coil, the mutual inductance between the three-phase receiving coil and the transmitting coil is M. TA =M TB =M0, M TC =M1, based on the voltage equalization control requirements, it can be known that the adjustable range of the load voltage is [0, U]. ref ].

[0090] contrast Figure 3 and​ Figure 4 Fixed load R Lm With R0, the adjustable range of the load voltage in the asymmetric coupling system after dynamic offset adjustment of the receiving coil is wider; the fixed load voltage reference value U ref In this case, the asymmetric coupling system with dynamic offset adjustment of the receiving coil has a wider load variable range.

[0091] This invention designs an asymmetric coupled multi-frequency wireless power transfer wide-range voltage equalization control method. Based on the asymmetric coil mutual inductance wireless connection between the transmitter and the three loads connected to the receiver, and the DC power supply in the transmitter connected to the transmitting coil via an inverter, the method employs load voltage closed-loop control based on multi-frequency SPWM waveform modulation control, combined with dynamic offset control of the receiving coil, including longitudinal offset control, lateral offset control, and angular offset control, thereby providing a balanced and stable voltage for the three-phase loads. With efficient energy transfer as a prerequisite, under constant load conditions, it widens the adjustable range of the load voltage of the voltage equalization output system; under constant load voltage reference conditions, it widens the variable range of each phase load, making it suitable for voltage equalization control in multi-frequency, multi-load wireless power transfer systems under variable load conditions. This invention has broad application prospects, including intelligent charging of multiple portable devices, dynamic charging of electric vehicles, and wireless motor drive.

[0092] The above are merely preferred embodiments of the present invention, but do not limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of the present invention specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of the present invention.

Claims

1. A wide-range voltage equalization control method for asymmetric coupled multi-frequency wireless power transfer, characterized in that: A wireless power transmission system based on the asymmetrical coil mutual inductance wireless connection between the transmitter and the receivers connected to three loads. The DC power supply in the transmitter is connected to the transmitting coil via an inverter. The inverter includes two parallel bridge arms. The first bridge arm includes an upper bridge arm switch Q1 and a lower bridge arm switch Q2 connected in series. The second bridge arm includes an upper bridge arm switch Q3 and a lower bridge arm switch Q4 connected in series. The receivers connected to the three loads are receiver A, receiver B, and receiver C, respectively. The following steps are performed to achieve voltage control of the three loads. Step A1: Collect the actual voltage u corresponding to the three loads respectively. LA u LB u LC and the operating frequencies f corresponding to the three loads respectively. A f B f C and obtain u LA u LB u LC With preset reference voltage u ref Find the difference between them, and then proceed to step A2; Step A2: For u respectively LA u LB u LC With preset reference voltage u ref The difference between them is PI-regulated to obtain the SPWM modulation level a corresponding to phases A, B, and C respectively. rA a rB a rC Then proceed to step A3; Step A3: For a respectively rA a rB a rC Amplitude limiting is applied, with the limiting range set to [0, a]. rth If a rA a rB a rC None of them are greater than the preset modulation threshold a rth Adjustment system a rA a rB a rC Keeping the voltage unchanged, proceed to steps A4 and A5 to adjust the voltages corresponding to the three loads to the preset reference voltage u. ref This enables voltage control of three loads; if there exists a rm Greater than the preset modulation threshold a rth Execute step A6 to adjust the m-phase modulation regime a rm Limit to a rth Then, perform steps A4 to A5 to adjust the voltages corresponding to the three loads to the preset reference voltage u. ref This enables voltage control of three loads; where m represents the receiving end, m = A represents receiving end A, m = B represents receiving end B, and m = C represents receiving end C. Step A4: Adjust the modulation level a rA With sin(2πf) A t) multiplication, a rB With sin(2πf) B t) multiplication, a rC With sin(2πf) C Multiply by t) to obtain the modulation waves a corresponding to phases A, B, and C respectively. rA sin(2πf A t), a rB sin(2πf B t), a rC sin(2πf C t); Step A5: Drive switches Q1 and Q4 based on the multi-frequency SPWM control signal obtained by subtracting the sum of the modulation waves of phases A, B, and C from the preset carrier wave; drive switches Q2 and Q3 based on the multi-frequency SPWM control signal obtained by subtracting the sum of the modulation waves of phases A, B, and C from the preset carrier wave and then inverting it; so that the voltages corresponding to the three loads reach the preset reference voltage u. ref This enables voltage control of three loads; Step A6: Start the m-phase receiving coil offset adjustment, targeting the corresponding a for m. rm With a rth The difference is adjusted using a PI controller to obtain the offset of the m-phase receiving coil.

2. The asymmetric coupled multi-frequency wireless power transfer wide-range voltage equalization control method according to claim 1, characterized in that: The m-phase receiving coil offset adjustment includes longitudinal offset adjustment, lateral offset adjustment, and angular offset adjustment.

3. The asymmetric coupled multi-frequency wireless power transfer wide-range voltage equalization control method according to claim 2, characterized in that: In step A6, the offset of the m-phase receiving coil is obtained through the following steps: When the m-phase receiving coil offset adjustment is set to longitudinal offset adjustment, for m-phase a rm With a rth The difference is used for PI adjustment, combined with limiting the adjustment range [h] ma h mb ], obtain the longitudinal offset h of the m-phase receiving coil m ; When the m-phase receiving coil offset adjustment is set to lateral offset adjustment, for m-phase a rm With a rth The difference is used for PI adjustment, combined with limiting the adjustment range [Δ]. ma Δ mb ], obtain the lateral offset Δ of the m-phase receiving coil m ; When the m-phase receiving coil offset adjustment is set to angle offset adjustment, for m-phase a rm With a rth The difference is used for PI adjustment, combined with limiting the adjustment range [α]. ma α mb ], obtain the angular offset α of the m-phase receiving coil. m .

4. The asymmetric coupled multi-frequency wireless power transfer wide-range voltage equalization control method according to claim 3, characterized in that: The adjustment ranges for the longitudinal offset, lateral offset, and angular offset of the m-phase are obtained through the following steps: Step B1: Obtain the outer diameter r of the transmitting coil To Number of turns N T Turn spacing p, internal resistance R T Obtain the outer diameter r of the m-phase receiving coil. mo Number of turns N m , turn spacing p m Internal resistance R m Furthermore, the outer diameters of the receiving coils in phases A, B, and C are the same, i.e.: r Ao =r Bo =r Co Then proceed to step B2; Step B2: Obtain the initial longitudinal offset h0, initial lateral offset Δ0, and initial angular offset α0 of the receiving coils of phases A, B, and C relative to the transmitting coil, and then proceed to step B3; Step B3: Based on the preset transmission efficiency threshold η of the wireless power transmission system th m-phase load resistance R Lm The operating frequency f corresponding to the m-phase load m The minimum adjustable mutual inductance M between the m-phase receiving coil and transmitting coil is obtained according to the following formula. Tma Proceed to step B4: Step B4: The adjustment range for the longitudinal offset adjustment of phase m is obtained through steps B5-B6; the adjustment range for the lateral offset adjustment of phase m is obtained through steps B7-B8; the adjustment range for the angular offset adjustment of phase m is obtained through steps B9-B10. Step B5: Obtain the radius r of the i-th turn of the transmitting coil according to the following formula. Ti The radius r of the j-th turn of the receiving coil mj : In this case, the turn spacing between the transmitting coil and the receiving coil is the same, that is: p = p m ; Furthermore, based on the initial lateral offset Δ0 of phase m, the initial angular offset α0, and the minimum adjustable mutual inductance M between the phase m receiving coil and transmitting coil... Tma The upper limit h of the longitudinal offset adjustment range of phase m is obtained according to the following formula. mb : Where μ0 represents the free permeability; θ is the angle between the x-axis and the length vector of the transmitting coil in the coordinate system corresponding to the transmitting coil. It is the angle between the x' axis and the length vector of the receiving coil in the coordinate system corresponding to the m-phase receiving coil, where x represents the unit vector (1, 0, 0), y represents the unit vector (0, 1, 0), and z represents the unit vector (0, 0, 1). Then proceed to step B6. Step B6: Based on the distance between the m-phase receiving coil and the transmitting coil, obtain the lower limit h of the longitudinal offset adjustment range of the receiving coil. ma Thus, the limiting adjustment range of the m-phase longitudinal offset adjustment [h] is obtained. ma h mb ]; Step B7: Based on the initial longitudinal offset h0 of phase m, the initial angular offset α0, and the minimum adjustable mutual inductance M between the phase m receiving coil and transmitting coil. Tma The upper limit Δ of the lateral offset adjustment range of phase m is obtained according to the following formula. mb Then proceed to step B8; Step B8: Obtain the lower limit Δ of the lateral offset adjustment range of the receiving coil according to the following formula. ma Thus, the limiting adjustment range of the m-phase longitudinal offset adjustment [Δ] is obtained. ma Δ mb ]: Step B9: Based on the initial longitudinal offset h0 of phase m, the initial lateral offset Δ0, and the minimum adjustable mutual inductance M between the phase m receiving coil and transmitting coil. Tma The upper limit α of the lateral offset adjustment range of phase m is obtained according to the following formula. mb Then proceed to step B10: Step B10: Lower limit α of the receiving coil angle offset adjustment range ma Setting it to 0, we obtain the limiting adjustment range [α] for the m-phase angle offset adjustment. ma α mb ].

5. A topology based on the asymmetric coupled multi-frequency wireless power transfer wide-range voltage equalization control method according to any one of claims 1-4, characterized in that: It includes a transmitter, receiver A, receiver B, and receiver C. The transmitter and the three receivers are wirelessly connected via an asymmetrical coil mutual inductance system. The transmitter includes a DC power supply V. in Inverter, DC-side filter capacitor C r Compensation network, internal resistance R of transmitting coil T The inductance of the transmitting coil L T The inverter includes two parallel bridge arms. The first bridge arm includes an upper bridge arm switch Q1 and a lower bridge arm switch Q2 connected in series. The second bridge arm includes an upper bridge arm switch Q3 and a lower bridge arm switch Q4 connected in series. The compensation network is an LCC high-order compensation network, including an LCC series inductor L. p LCC parallel compensation capacitor C P Transmitter coil compensation capacitor C T ; DC power supply V in One end is connected to the DC-side filter capacitor C. r One end of the circuit, the drain of switching transistor Q1 and the drain of switching transistor Q3, DC power supply V in The other end is connected to the DC-side filter capacitor C. r The other end, the source of switch Q2 and the source of switch Q4; the source of switch Q1, the drain of switch Q2, and the LCC series inductor L. p One end of the three components is connected in parallel; the source of switching transistor Q3, the drain of switching transistor Q4, and the LCC are connected in parallel with the compensation capacitor C. P One end of the transmitting coil, internal resistance R T One end of the four components is connected in series; LCC series inductor L p At the other end, LCC is connected in parallel with compensation capacitor C. P At the other end, the transmitting coil compensation capacitor C T One end of the three components is connected in parallel; the transmitting coil compensation capacitor C T The other end is connected to the transmitting coil inductance L T One end of the transmitting coil is connected to the other end; the internal resistance R of the transmitting coil is... T The other end is connected to the transmitting coil inductance L T The other end is connected; Receiver A, Receiver B, and Receiver C have the same structure. The structure of each receiver is as follows: it includes a receiving coil and an inductor L. m The internal resistance R of the receiving coil m Receiver filter capacitor C mf rectifier and load resistor R Lm ; Receiver coil inductance L m One end of the receiver coil is connected to one end of the AC side of the rectifier; the receiving coil inductance L m The other end is connected to the internal resistance R of the receiving coil. m One end is connected; the internal resistance R of the receiving coil m The other end is connected to the other end of the AC side of the rectifier; one end of the DC side of the rectifier, the receiving end filter capacitor C mf One end, load resistor R Lm One end of the three components is connected in parallel; the other end of the rectifier's DC side and the receiving end filter capacitor C mf The other end, load resistor R Lm The other end of the three are connected.

6. The topology of the wide-range voltage equalization control method for asymmetric coupled multi-frequency wireless power transfer according to claim 5, characterized in that: The receiving end also includes an S-type compensation network and a blocking network; the receiving coil inductance L m One end of the circuit is sequentially connected to one end of the rectifier's AC side via a blocking network and an S-type compensation network; the blocking network includes a blocking network inductor L. m1 Blocking network inductor L m2 Blocking network compensation capacitor C m1 Blocking network compensation capacitor C m2 The S-type compensation network includes a receiving coil compensation capacitor C. m ; Receiver coil inductance L m One end of the blocking network inductor L m1 One end of the blocking network compensation capacitor C m1 One end of the three components is connected to the other; blocking network inductor L m1 The other end, the blocking network compensation capacitor C m1 The other end, blocking network inductor L m2 One end of the blocking network compensation capacitor C m2 One end of the four components is connected to each other; blocking network inductor L m2 The other end, the blocking network compensation capacitor C m2 The other end, receiving coil compensation capacitor C m One end of the three components is connected in parallel; the receiving coil compensation capacitor C m The other end is connected to one end of the AC side of the rectifier.

Images