A Multi-Frequency and Multi-Load Wireless Power Transfer Control Method

Abstract

The present invention relates to a multi - frequency and multi - load wireless power transfer control method. Based on the wireless connection of the mutual inductance of coils between the transmitting end and the receiving ends respectively connected to at least one preset load, and the connection of the DC power supply in the transmitting end to the transmitting coil through an inverter, the design includes single - frequency energy transfer control and dual - frequency energy transfer control, providing stable voltage for the corresponding load. Both designs adopt closed - loop control to balance the output power. By directly controlling the driving signal of the inverter, the output voltage of the inverter is changed, without the need to add an additional step - up / step - down circuit, reducing the system volume and cost. And the design is applicable to the application scenarios of single - power - source and multi - load wireless power transfer. In both the single - frequency output mode and the dual - frequency output mode, load selective conduction can be achieved. In addition, in both the single - frequency output mode and the dual - frequency output mode, the load power can track the target power, realizing multi - load power balance and being applicable to the occasion of multi - load time - division multiplexing conduction.

Description

Technical Field

[0001] The present invention relates to a multi - frequency and multi - load wireless power transfer control method, belonging to the technical field of wireless power transfer control. Background Art

[0002] Wireless power transfer (WPT) technology has many advantages such as reliability, safety, and convenience. Compared with traditional cable transmission technology, it can better adapt to humid and harsh environments. Currently, WPT technology has been applied in fields such as electric vehicles and motor drives.

[0003] According to different transmission mechanisms, WPT systems can be divided into categories such as magnetic - field - coupled type, electric - field - coupled type, electromagnetic - radiation type, and ultrasonic type. The magnetic - field - coupled type can be divided into two categories: magnetic - coupled inductive type and magnetic - coupled resonant type. The magnetic - coupled inductive type is suitable for occasions of short - distance transmission, while the magnetic - coupled resonant type can achieve energy transmission over a longer distance compared with the magnetic - coupled inductive type. The magnetic - coupled resonant WPT system mainly includes: a power source, an inverter, a transmitting coil and its compensation network, a receiving coil and its compensation network, a rectifier, and a load.

[0004] The power supply objects of WPT systems can be divided into single - load and multi - load. The single - load WPT system has the disadvantages of a unique load and low system utilization rate. Therefore, the multi - load WPT system came into being. Currently, the multi - load WPT system can be divided into single - input multi - output (SIMO) and multi - input multi - output (MIMO) systems. The transmitting end of the MIMO system contains multiple power sources and inverters, which makes the structure of the transmitting end large and the design of loop parameters and coil parameters complex. The transmitting end of the SIMO system contains only one power source, has a large output power density, a simple structure, and low cost.

[0005] Most of the existing multi - load WPT systems focus on the simultaneous transmission of multi - load energy, while the WPT system with the ability of selective load conduction can only achieve single - frequency energy transmission. The existing systems cannot meet the requirements of both single - frequency energy transmission and dual - frequency energy transmission at the same time.

[0006] In practical applications, the multi - load WPT system should have the characteristics of load identification ability and power controllability. In particular, the motor drive field usually requires the power balance of each phase of the motor to reduce torque ripple. Currently, the research on the output power balance of the multi - load WPT system mainly focuses on the optimization of topological structure and parameter design, which can achieve load power balance under the open - loop operation of the system, but the system cannot automatically adjust parameters to track the change of the target power. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a multi - frequency and multi - load wireless power transfer control method, which can automatically adjust parameters to balance the output power and achieve selective single - frequency energy transmission and dual - frequency energy transmission.

[0008] The present invention adopts the following technical solutions to solve the above technical problems: The present invention designs a multi-frequency and multi-load wireless power transmission control method, which is wirelessly connected based on the mutual inductance of coils between the transmitting end and the receiving ends respectively connected to at least one preset load, and a DC power supply in the transmitting end is connected to a transmitting coil through an inverter. The control method includes single-frequency energy transmission control, which is carried out according to the following steps A1 to A5 to achieve voltage control of the load;

[0009] Step A1. Collect the actual voltage U of a specified target load 目 and the operating frequency f of the target load 目 , and obtain the difference between U 目 and a preset reference voltage U ref , and then enter Step A2;

[0010] Step A2. Perform PI adjustment on the difference between U 目 and U ref to obtain the duty ratio D S of the switching tube drive signal of the inverter, and then enter Step A3;

[0011] Step A3. Based on the Taylor expansion of the output voltage U S on the AC side of the inverter in the transmitting end at the duty ratio D = D S of the switching tube drive signal of the inverter, according to the following formula:

[0012]

[0013] Obtain the control quantity G1(S) of the output voltage on the AC side of the inverter;

[0014] At the same time, according to the following formula:

[0015]

[0016] Obtain the interference quantity G2(S) of the output voltage on the AC side of the inverter, and then enter Step A4;

[0017] Step A4. According to the following formula:

[0018]

[0019] Obtain the output voltage U S on the AC side of the inverter in the transmitting end, and then enter Step A5;

[0020] Step A5. Based on the inverter operating at the operating frequency f O = f 目 to operate, the output voltage U SWirelessly transmit in the direction of the receiving coils in the respective receivers connected to each load via the transmitting coil, and each load with a working frequency equal to f 目 receives through the receiving coils in the respective receivers connected thereto, stably controls the voltage across each load, and then returns to step A1.

[0021] As a preferred technical solution of the present invention: Based on an inverter including a first bridge arm and a second bridge arm connected in parallel, the first bridge arm includes a first switching tube Q1 and a second switching tube Q2 connected in series, and the second bridge arm includes a third switching tube Q3 and a fourth switching tube Q4 connected in series. The control method includes dual-frequency energy transfer control, and is performed according to the following steps B1 to B5 to achieve voltage control of the load;

[0022] Step B1. Collect the actual voltage U of a specified first target load 目1 , the actual voltage U of the second target load 目2 , as well as the working frequency f of the first target load 目1 , the working frequency f of the second target load 目2 , and obtain the difference between U 目1 and the preset reference voltage U ref , as well as the difference between U 目2 and the preset reference voltage U ref , and then enter step B2;

[0023] Step B2. Perform PI regulation on the difference between U 目1 and U ref to obtain the duty cycle D of the drive signals of the first switching tube Q1 and the second switching tube Q2 on the first bridge arm of the inverter S1 , and perform PI regulation on the difference between U 目2 and U ref to obtain the duty cycle D of the drive signals of the third switching tube Q3 and the fourth switching tube Q4 on the second bridge arm of the inverter S2 , and then enter step B3;

[0024] Step B3. Based on k = 1, 2, according to the output voltage of the corresponding k-th target load on the AC side of the inverter in the transmitter at the duty cycle D of the drive signals of the switching tubes on the k-th bridge arm of the inverter Ok = D Sk perform Taylor expansion, according to the following formula:

[0025]

[0026] obtain the control quantity of the output voltage of the corresponding k-th target load on the AC side of the inverter

[0027] Meanwhile, according to the following formula:

[0028]

[0029] Obtain the interference amount of the output voltage corresponding to the k-th target load on the AC side of the inverter Then enter step B4; Step B4. According to the following formula:

[0030]

[0031] Obtain the output voltage corresponding to the k-th target load on the AC side of the inverter in the transmitting end Then enter step B5;

[0032] Step B5. Based on each switching tube on the first bridge arm in the inverter operating at the operating frequency f O1 = f 目1 to operate, the output voltage of the AC side of the inverter is wirelessly transmitted in the direction of the receiving coil in the receiving end connected to each load through the transmitting coil, and each load with an operating frequency equal to f 目1 receives through the receiving coil in the receiving end connected thereto, and the voltage across each load is stably controlled;

[0033] Meanwhile, based on each switching tube on the second bridge arm in the inverter operating at the operating frequency f O2 = f 目2 to operate, the output voltage of the AC side of the inverter is wirelessly transmitted in the direction of the receiving coil in the receiving end connected to each load through the transmitting coil, and each load with an operating frequency equal to f 目2 receives through the receiving coil in the receiving end connected thereto, and the voltage across each load is stably controlled; Then return to step B1.

[0034] As a preferred technical solution of the present invention: In the wireless connection of the mutual inductance of the coils between the transmitting end and the receiving ends connected to each load, the transmitting end further includes an LCC-type compensation network, and the inverter further includes diodes corresponding to the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 respectively. In the structure of the transmitting end: the drain electrodes of the switching tubes in the inverter are connected to the cathodes of the corresponding diodes, and the source electrodes of the switching tubes are connected to the anodes of the corresponding diodes; the positive electrode of the DC power supply V in is connected to the drain electrode of the first switching tube Q1 and the drain electrode of the third switching tube Q3, and the negative electrode of the DC power supply V in is connected to the source electrode of the second switching tube Q2 and the source electrode of the fourth switching tube Q4;

[0035] The source electrode of the first switching tube Q1 is connected to the drain electrode of the second switching tube Q2, and the connected end is connected to the series inductor L in the LCC-type compensation networkp One end of the third switching transistor Q3 is connected to the drain of the fourth switching transistor Q4, and the connected end is connected to the parallel compensation capacitor C in the LCC compensation network P One end of the internal resistance R in the transmitting coil T One end of the series inductor L in the LCC compensation network p The other end of the parallel compensation capacitor C in the LCC compensation network P The other end of the compensation capacitor C in the transmitting coil T One end of the compensation capacitor C in the transmitting coil T The other end of the compensation capacitor C in the transmitting coil is connected to one end of the transmitting coil inductor L T One end of the internal resistance R in the transmitting coil T The other end of the internal resistance R in the transmitting coil is connected to the other end of the transmitting coil inductor L T The other end of the transmitting coil inductor L T The transmitting coil inductor L is wirelessly connected to the receiving coil inductance L in the receiving end connected to each load, where m = {1,..., n}, and n represents the number of all loads; m The structures of the receiving ends connected to each load are the same. Each receiving end further includes a rectifier and a filter capacitor C

[0036] In the structure of each receiving end: One end of the receiving coil inductance L fm is connected to one end of the receiving coil compensation capacitor C m One end of the receiving coil inductance L m is connected to one end of the receiving coil compensation capacitor C m The other end of the receiving coil inductance L is connected to one end of the receiving coil internal resistance R m One end of the receiving coil internal resistance R m The other end is connected to one end of the AC side of the rectifier. The other end of the receiving coil compensation capacitor C m is connected to the other end of the AC side of the rectifier; One end of the DC side of the rectifier is connected to one end of the filter capacitor C fm is connected to one end of the corresponding load; The other end of the DC side of the rectifier is connected to the other end of the filter capacitor C fm is connected to the other end of the corresponding load.

[0037] As a preferred technical solution of the present invention: In the single - frequency energy transmission control, when the output voltage U of the AC side of the inverter is wirelessly transmitted in the direction of the receiving coil in the receiving end connected to each load, according to the following formula: S When the output voltage U of the AC side of the inverter is wirelessly transmitted in the direction of the receiving coil in the receiving end connected to each load, according to the following formula:

[0038]

[0039] Obtain the load equivalent resistance \(R\) referred to the AC side of the rectifier in each receiver connected to the load Leqm , where \(R\) Leqm represents the load equivalent resistance referred to the AC side of the rectifier in the receiver connected to the \(m\)th load, and \(R\) Lm represents the resistance of the \(m\)th load;

[0040] Then, according to the following formula:

[0041]

[0042] Obtain the impedance \(Z\) of each receiver m , where \(Z\) m represents the impedance of the receiver connected to the \(m\)th load, \(\omega\) o represents the operating angular frequency of the inverter, \(i\) is the imaginary unit, \(L\) m represents the receiving coil inductance of the receiver connected to the \(m\)th load, \(C\) m represents the receiving coil compensation capacitance of the receiver connected to the \(m\)th load, and \(R\) m represents the internal resistance of the receiving coil of the receiver connected to the \(m\)th load;

[0043] Then, based on the mutual inductance between the receiving coils of each receiver being 0, according to the following formula:

[0044]

[0045] Successively obtain the reflected impedance \(Z\) ref and the equivalent input impedance \(Z\) S , where \(M\) Tm represents the mutual inductance between the transmitting coil and the receiving coil in the receiver connected to the \(m\)th load, and / / represents the parallel relationship formed between the two objects;

[0046] Finally, based on \(j\) representing the sequence number of each load in the controlled sorting of the loads with the same operating frequency as the target load, according to the following formula:

[0047]

[0048] Obtain the voltage gain \(K\) received by each load with the same operating frequency as the target load j \((\omega\) o )R Leqj , where \(R\) Leqj represents the load equivalent resistance referred to the AC side of the rectifier in the receiver connected to the \(j\)th load in the controlled sorting, and \(K\) j \((\omega\) o )R Leqj represents the voltage gain received by the \(j\)th load in the controlled sorting, and \(Z\) j represents the impedance of the receiver connected to the \(j\)th load in the controlled sorting, and \(M\)Tj It represents the mutual inductance between the transmitting coil and the receiving coil in the receiving end connected to the jth load in the controlled sorting.

[0049] As a preferred technical solution of the present invention: in the dual-frequency energy transmission, the output voltage of the AC side of the inverter is in a wireless transmission state in the direction of the receiving coil in the receiving end respectively connected to each load through the transmitting coil, and the output voltage of the AC side of the inverter is in a wireless transmission state in the direction of the receiving coil in the receiving end respectively connected to each load through the transmitting coil. According to the following formula:

[0050]

[0051] the equivalent load resistance R reduced to the AC side of the rectifier in the receiving end connected to each load is obtained Leqm , where R Leqm represents the equivalent load resistance reduced to the AC side of the rectifier in the receiving end connected to the mth load, and R Lm represents the resistance of the mth load;

[0052] Then, according to the following formula:

[0053]

[0054] the impedance of each receiving end corresponding to the kth target load is obtained where represents the impedance of the receiving end connected to the mth load corresponding to the kth target load, ω ok represents the operating angular frequency of the switching tube of the kth bridge arm of the inverter, l is the imaginary unit, L m represents the inductance of the receiving coil in the receiving end connected to the mth load, C m represents the compensation capacitor of the receiving coil in the receiving end connected to the mth load, and R m represents the internal resistance of the receiving coil in the receiving end connected to the mth load;

[0055] Then, based on the mutual inductance between the receiving coils of each receiver being 0, according to the following formula:

[0056]

[0057] the reflected impedance corresponding to the kth target load is obtained in sequence the equivalent input impedance corresponding to the kth target load where M Tm represents the mutual inductance between the transmitting coil and the receiving coil in the receiving end connected to the mth load, and / / represents the parallel relationship formed between two objects;

[0058] Finally, based on e representing the sequence numbers of each load with the same operating frequency as the first target load in the first controlled sorting, and g representing the sequence numbers of each load with the same operating frequency as the second target load in the second controlled sorting, according to the following formula:

[0059]

[0060]

[0061] Obtain the voltage gain received by each load with the same operating frequency as the first target load where, R Leqe represents the load equivalent resistance reduced to the AC side of the rectifier in the receiving end connected to the e-th load in the first controlled sorting, represents the voltage gain received by the e-th load in the first controlled sorting, represents the impedance of the receiving end connected to the e-th load in the first controlled sorting, M Te represents the mutual inductance between the transmitting coil and the coil connected in the receiving end connected to the e-th load in the first controlled sorting;

[0062] And obtain the voltage gain received by each load with the same operating frequency as the second target load where, R Leqg represents the load equivalent resistance reduced to the AC side of the rectifier in the receiving end connected to the g-th load in the second controlled sorting, represents the voltage gain received by the g-th load in the second controlled sorting, represents the impedance of the receiving end connected to the g-th load in the second controlled sorting, M Tg represents the mutual inductance between the transmitting coil and the coil connected in the receiving end connected to the g-th load in the second controlled sorting.

[0063] For the multi-frequency and multi-load wireless power transmission control method described in the present invention, compared with the prior art by adopting the above technical solutions, it has the following technical effects:

[0064] The present invention designs a multi - frequency and multi - load wireless power transfer control method. Based on the wireless connection of mutual inductance of coils between the transmitter and the receivers respectively connected to at least one preset load, and the DC power supply in the transmitter is connected to the transmitting coil through an inverter, the design includes single - frequency energy transfer control and dual - frequency energy transfer control, which provides a stable voltage for the corresponding load. The design adopts closed - loop control to balance the output power. By directly controlling the driving signal of the inverter, the output voltage of the inverter is changed, without adding an additional step - up / step - down circuit, reducing the system volume and cost. And the design is applicable to the application scenarios of single - power - supply and multi - load wireless power transfer. In both the single - frequency output mode and the dual - frequency output mode, load selective conduction can be achieved. In addition, in both the single - frequency output mode and the dual - frequency output mode, the load power can track the target power to achieve multi - load power balance, and it is applicable to the occasion of multi - load time - division multiplexing conduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 is a flowchart of a multi - frequency and multi - load wireless power transfer control method designed by the present invention

[0066] Figure 2 is a schematic diagram of the overall structure of a multi - frequency and multi - load circuit of the present invention;

[0067] Figure 3 is an equivalent circuit diagram of the single - frequency output mode of a multi - frequency and multi - load circuit of the present invention;

[0068] Figure 4 is a power flow diagram of the single - frequency output mode of a multi - frequency and multi - load circuit of the present invention;

[0069] Figure 5 is an equivalent circuit diagram of the dual - frequency output mode of a multi - frequency and multi - load circuit of the present invention;

[0070] Figure 6 is a power flow diagram of the dual - frequency output mode of a multi - frequency and multi - load circuit of the present invention;

[0071] Figure 7 is a closed - loop control block diagram in the single - frequency output mode;

[0072] Figure 8 is a closed - loop control block diagram in the dual - frequency output mode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0073] The following further details the specific embodiments of the present invention with reference to the accompanying drawings of the specification.

[0074] The present invention designs a multi - frequency and multi - load wireless power transfer control method. Based on the wireless connection of mutual inductance of coils between the transmitter and the receivers respectively connected to at least one preset load, the design is for the wireless power transfer control of multi - frequency and multi - load. Among them, as Figure 2As shown, the transmitting end includes a DC power supply, an inverter, an LCC type compensation network, and a transmitting coil; wherein the inverter includes a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4, and diodes corresponding to each switch tube; in the structure of the transmitting end: the drain of each switch tube in the inverter is connected to the cathode of the corresponding diode, and the source of each switch tube is connected to the anode of the corresponding diode; the DC power supply V in The positive electrode of the first switch tube Q1, the drain of the third switch tube Q3 are connected, and the DC power supply V in The negative electrode of the first switch tube Q1, the source electrode of the second switch tube Q2, and the source electrode of the fourth switch tube Q4 are connected; the source electrode of the first switch tube Q1 is connected to the drain electrode of the second switch tube Q2, and the connected end is connected to the series inductor L in the LCC type compensation network. p The source of the third switch tube Q3 is connected to the drain of the fourth switch tube Q4, and the connected end is connected to the parallel compensation capacitor C in the LCC type compensation network. P One end of the transmitting coil, the internal resistance R T One end of the LCC compensation network; the series inductor L p The other end of the LCC compensation network is connected in parallel with the compensation capacitor C P The other end of the transmitting coil, the compensation capacitor C T The three are connected to each other at one end; the compensation capacitor C in the transmitting coil T The other end of the transmitting coil inductor L T One end of the transmitting coil is connected to the other, and the internal resistance R T The other end of the transmitting coil inductor L T The other end of the transmitting coil is connected; the inductance L T The receiving coil inductance L in the receiving end connected to each load m The coil mutual inductance is wirelessly connected, wherein m={1, ..., n}, and n represents the number of all loads.

[0075] The structures of the receiving ends to which the loads are connected are the same, and each receiving end also includes a rectifier, a filter capacitor C fm , in the structure of each receiving end: the receiving coil inductance L m One end of the receiving coil compensation capacitor C m One end of the receiving coil is connected to the inductance L m The other end of the receiving coil is connected to the internal resistance R m One end of the receiving coil is connected; the internal resistance R m The other end is connected to one end of the rectifier AC side, and the receiving coil compensation capacitor C m The other end of the rectifier is connected to the other end of the AC side of the rectifier; one end of the DC side of the rectifier is connected to the filter capacitor C fmOne end of which is connected, and the connected end is connected to one end of the corresponding load; the other end of the DC side of the rectifier is connected to the other end of the filter capacitor C fm The other end of which is connected, and the connected end is connected to the other end of the corresponding load.

[0076] Based on the wireless connection of the mutual inductance of the coils between the transmitting end and the receiving ends respectively connected to the preset at least one load, the multi-frequency and multi-load wireless power transmission control method designed by the present invention includes single-frequency energy transmission control and dual-frequency energy transmission control. Among them, the single-frequency energy transmission control is as Figure 3 shown. Denote f1, f2,... f n as the resonance frequencies of the receiving ends 1, 2,... n. The single-frequency output mode means that the operating frequency of the inverter at the transmitting end is f o , then the output voltage of the inverter only contains the voltage fundamental component with the frequency of f o In this mode, ω o is the system operating angular frequency; D is the duty cycle of the driving signal of the switching tube Q1; R Leqm is the equivalent load resistance in the rectifier circuit; is the current at the transmitting end; are the currents on the loads 1, 2,... n; are the voltages on the loads 1, 2,... n.

[0077] As Figure 4 shown, in the single-frequency output mode, if there are h (0 < h ≤ n) target receiving ends with the loop resonance frequencies f j = f o (j = 1, 2,... h), then at the same moment, the loops of the target receiving ends are in series resonance, and the reflected impedance formed at the transmitting end is much larger than that of the non-target receiving ends. The voltage fundamental component with the frequency of f o excites the target receiving ends 1, 2,... h.

[0078] The single-frequency energy transmission control is as Figure 1 and Figure 7 shown. The specific design is implemented according to the following steps A1 to A5 to achieve the voltage control of the load.

[0079] Step A1. Collect the actual voltage U 目 of the specified target load and the operating frequency f 目 of the target load, and obtain the difference between U 目 and the preset reference voltage U ref , and then enter step A2.

[0080] Step A2. For the difference between U 目 and U ref ​​Perform PI regulation on the difference to obtain the duty cycle D of the switching tube drive signal of the inverter S , and then enter step A3.

[0081] In practical applications, in the above steps A1 to A2, such as designing to use a voltage sensor to collect the actual voltage U of a specified target load 目 , and transmit it to the controller through a preset communication method such as Bluetooth. The controller processes this to obtain U 目 The difference between and the preset reference voltage U ref , and perform PI regulation on the difference between U 目 and U ref to obtain the duty cycle D of the switching tube drive signal of the inverter S .

[0082] Step A3. Based on the Taylor expansion of the output voltage U of the AC side of the inverter in the transmitter at the duty cycle D = D S of the switching tube drive signal of the inverter, according to the following formula: S Obtain the control quantity G1(S) of the output voltage of the AC side of the inverter.

[0083]

[0084] At the same time, according to the following formula:

[0085] Obtain the interference quantity G2(S) of the output voltage of the AC side of the inverter, and then enter step A4.

[0086]

[0087]

[0088] Step A4. According to the following formula:

[0089]

[0090] Obtain the output voltage U of the AC side of the inverter in the transmitter S , and then enter step A5.

[0091] Step A5. Based on the inverter operating at the operating frequency f O = f 目 to operate, the output voltage U of the AC side of the inverter is wirelessly transmitted in the direction of the receiving coil in each load-connected receiver through the transmitting coil, and is received by each load with an operating frequency equal to f S 目 through the receiving coil in the receiver connected to it, and the voltage across each load is stably controlled, and then return to step A1.

[0092]

[0092] Correspondingly, in practical applications of single - frequency energy transmission control, the output voltage U of the AC side of the inverter S is in a wireless transmission state in the direction of the receiving coil in each receiver connected to each load through the transmitting coil. According to the following formula:

[0093]

[0094] the equivalent load resistance R reduced to the AC side of the rectifier in each receiver connected to each load is obtained Leqm , where R Leqm represents the equivalent load resistance reduced to the AC side of the rectifier in the receiver connected to the m - th load, and R Lm represents the resistance of the m - th load.

[0095] Then, according to the following formula:

[0096]

[0097] the impedance Z of each receiver is obtained m , where Z m represents the impedance of the receiver connected to the m - th load, ω o represents the operating angular frequency of the inverter, l is the imaginary unit, L m represents the inductance of the receiving coil in the receiver connected to the m - th load, C m represents the compensation capacitor of the receiving coil in the receiver connected to the m - th load, and R m represents the internal resistance of the receiving coil in the receiver connected to the m - th load.

[0098] Then, based on the mutual inductance between the receiving coils of each receiver being 0, according to the following formula:

[0099]

[0100] the reflected impedance Z ref and the equivalent input impedance Z S are obtained in sequence, where M Tm represents the mutual inductance between the transmitting coil and the receiving coil in the receiver connected to the m - th load, and / / represents the parallel relationship formed between two objects.

[0101] Finally, based on j representing the sequence number of each load in the controlled sorting of each load with the same operating frequency as the target load, according to the following formula:

[0102]

[0103] the voltage gain K received by each load with the same operating frequency as the target load is obtained j (ω o )R Leqj, where R Leqj Indicates the load equivalent resistance of the receiving end connected to the jth load in the controlled sequence, which is calculated to the AC side of the rectifier, K j (ω o )R Leqj It represents the voltage gain received by the jth load in the controlled sequence, Z j It represents the impedance of the receiving end connected to the jth load in the controlled sequence, M Tj It represents the mutual inductance between the transmitting coil and the coil connected to the receiving end of the jth load in the controlled sequence.

[0104] Dual frequency energy transmission control, such as Figure 5 As shown, the driving signal frequency f of the first bridge arm switch tube Q1, Q2 of the transmitter inverter o1 , the second bridge arm switch tube Q3, Q4 drive signal frequency f o2 (f o1 ≠f o2 ), then the inverter output voltage contains a frequency of f o1 , f o2 The voltage fundamental component It can be regarded as the superposition of two single-frequency systems. In this mode, ω o1 With ω o2 is the system operating angular frequency; D o1 With D o2 They are the duty cycle of the driving signal of the upper bridge arm switch tube Q1 of the first bridge arm and the duty cycle of the driving signal of the upper bridge arm switch tube Q3 of the second bridge arm. The driving signals of the upper and lower tubes of each bridge arm are complementary. The operating frequency is f oi (i=1,2), is the transmitter current, is the current on loads 1, 2, ...n, is the voltage on loads 1, 2, ...n

[0105] like Figure 6 As shown, in dual-frequency output mode, if there is p(0 <p<n)个回路谐振频率f e =f o1 (e=1,2,…p) target receiving end, q(0 <q<n且0<p+q≤n)个回路谐振频率f g =f o2 (g=p+1,p+2,…p+q) is the target receiving end. At the same time, the target receiving end loop is in series resonance, and the reflected impedance formed at the transmitting end is much greater than that of the non-target receiving end. The frequency is f o1 The voltage fundamental component Stimulate the target receiving end 1, 2, ... p, with a frequency of f o2 The voltage fundamental component Stimulate the target receiving terminals p+1, p+2, …p+q.

[0106] Specifically regarding the dual - frequency energy transfer control, as Figure 1 and Figure 8 shown, the following steps B1 to B5 are designed to implement the voltage control of the load.

[0107] Step B1. Collect the actual voltage U of the specified first target load 目1 , the actual voltage U of the second target load 目2 , as well as the operating frequency f of the first target load 目1 , the operating frequency f of the second target load 目2 , and obtain the difference between U 目1 and the preset reference voltage U ref , and the difference between U 目2 and the preset reference voltage U ref , then enter Step B2.

[0108] Step B2. Perform PI regulation on the difference between U 目1 and U ref to obtain the duty cycle D of the drive signals of the first switch Q1 and the second switch Q2 on the first arm of the inverter S1 , and perform PI regulation on the difference between U 目2 and U ref to obtain the duty cycle D of the drive signals of the third switch Q3 and the fourth switch Q4 on the second arm of the inverter S2 , then enter Step B3.

[0109] In practical applications, in the above Steps B1 to B2, for example, it is designed to use a voltage sensor to collect the actual voltage U of the specified first target load 目1 , the actual voltage U of the second target load 目2 , and transmit it to the controller through a preset communication method such as Bluetooth. The controller processes this to obtain the difference between U 目1 and U ref , and perform PI regulation to obtain the duty cycle D of the drive signals of the first switch Q1 and the second switch Q2 on the first arm of the inverter S1 , and the difference between U 目2 and U ref , and perform PI regulation to obtain the duty cycle D of the drive signals of the third switch Q3 and the fourth switch Q4 on the second arm of the inverter S2 .

[0110] Step B3. Based on k = 1, 2, according to the output voltage of the corresponding k - th target load on the AC side of the inverter at the transmitting end at the duty cycle D of the drive signals of the switch on the k - th arm of the inverter Ok = DSk Taylor expansion at [specific location] is carried out according to the following formula:

[0111]

[0112] Obtain the control quantity of the output voltage of the inverter's AC side corresponding to the k-th target load

[0113] Meanwhile, according to the following formula:

[0114]

[0115] Obtain the interference quantity of the output voltage of the inverter's AC side corresponding to the k-th target load Then enter step B4.

[0116] Step B4. According to the following formula:

[0117]

[0118] Obtain the output voltage of the inverter's AC side corresponding to the k-th target load in the transmitter Then enter step B5.

[0119] Step B5. Based on the switching tubes on the first bridge arm of the inverter operating at the working frequency f O1 = f 目1 to operate, the output voltage of the inverter's AC side is wirelessly transmitted via the transmitting coil in the direction of the receiving coils in the receivers connected to each load respectively, and is received by each load with a working frequency equal to f 目1 via the receiving coils in the receivers connected to it respectively, and the voltage across each load is stably controlled.

[0120] Meanwhile, based on the switching tubes on the second bridge arm of the inverter operating at the working frequency f O2 = f 目2 to operate, the output voltage of the inverter's AC side is wirelessly transmitted via the transmitting coil in the direction of the receiving coils in the receivers connected to each load respectively, and is received by each load with a working frequency equal to f 目2 via the receiving coils in the receivers connected to it respectively, and the voltage across each load is stably controlled; then return to step B1.

[0121] Correspondingly, in the practical application of dual-frequency energy transfer control, when the output voltage of the inverter's AC side is in the state of being wirelessly transmitted via the transmitting coil in the direction of the receiving coils in the receivers connected to each load respectively, and when the output voltage of the inverter's AC side In the wireless transmission state of transmitting to the receiving coils of the receivers respectively connected to each load through the transmitting coil, according to the following formula:

[0122]

[0123] Obtain the load equivalent resistance R reduced to the AC side of the rectifier in the receivers connected to each load Leqm , where R Leqm represents the load equivalent resistance reduced to the AC side of the rectifier in the receiver connected to the m-th load, and R Lm represents the resistance of the m-th load.

[0124] Then, according to the following formula:

[0125]

[0126] Obtain the impedance of each receiver corresponding to the k-th target load where represents the impedance of the receiver connected to the m-th load corresponding to the k-th target load, ω ok represents the operating angular frequency of the switching tube of the k-th bridge arm of the inverter, l is the imaginary unit, L m represents the inductance of the receiving coil of the receiver connected to the m-th load, C m represents the compensation capacitor of the receiving coil of the receiver connected to the m-th load, and R m represents the internal resistance of the receiving coil of the receiver connected to the m-th load.

[0127] Then, based on the mutual inductance between the receiving coils of each receiver being 0, according to the following formula:

[0128]

[0129] Successively obtain the reflected impedance corresponding to the k-th target load The equivalent input impedance corresponding to the k-th target load where M Tm represents the mutual inductance between the transmitting coil and the receiving coil in the receiver connected to the m-th load, and / / represents the parallel relationship formed between two objects.

[0130] Finally, based on e representing the sequence number of each load in the first controlled sorting of each load with the same operating frequency as the first target load, and g representing the sequence number of each load in the second controlled sorting of each load with the same operating frequency as the second target load, according to the following formula:

[0131]

[0132]

[0133] Obtain the voltage gains received by each load having the same operating frequency as the first target load wherein, R Leqe represents the load equivalent resistance referred to the AC side of the rectifier in the receiving end connected to the e-th load in the first controlled sorting, represents the voltage gain received by the e-th load in the first controlled sorting, represents the impedance of the receiving end connected to the e-th load in the first controlled sorting, M Te represents the mutual inductance between the transmitting coil and the coil connected in the receiving end connected to the e-th load in the first controlled sorting.

[0134] And obtain the voltage gains received by each load having the same operating frequency as the second target load wherein, R Leqg represents the load equivalent resistance referred to the AC side of the rectifier in the receiving end connected to the g-th load in the second controlled sorting, represents the voltage gain received by the g-th load in the second controlled sorting, represents the impedance of the receiving end connected to the g-th load in the second controlled sorting, M Tg represents the mutual inductance between the transmitting coil and the coil connected in the receiving end connected to the g-th load in the second controlled sorting.

[0135] The multi-frequency and multi-load wireless power transmission control method designed by the above technical solution is based on the wireless connection of the mutual inductance of the coils between the transmitting end and the receiving ends respectively connected to at least one preset load, and the DC power supply in the transmitting end is connected to the transmitting coil through an inverter. The design includes single-frequency energy transmission control and dual-frequency energy transmission control, provides stable voltage for the corresponding load, and the design adopts closed-loop control to balance the output power. By directly controlling the driving signal of the inverter, the output voltage of the inverter is changed, without adding an additional step-up / step-down circuit, reducing the system volume and cost; and the design is applicable to the application occasion of single-source multi-load wireless power transmission. In the single-frequency output mode and the dual-frequency output mode, load selective conduction can be realized. In addition, in the single-frequency output mode and the dual-frequency output mode, the load power can track the target power, realizing multi-load power balance, and is applicable to the occasion of multi-load time-division multiplexing conduction.

[0136] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made without departing from the spirit of the present invention within the knowledge of those of ordinary skill in the art.

Claims

1. A multi - frequency and multi - load wireless power transfer control method, characterized in that: Based on the wireless connection of coil mutual inductance between the transmitting end and the receivers respectively connected to at least one preset load, and the DC power supply in the transmitting end is connected to the transmitting coil through an inverter, the control method includes single-frequency energy transfer control, which is carried out according to steps A1 to A5 as follows to achieve voltage control of the load; Step A1. Collect the actual voltage U of the specified target load 目 , and the operating frequency f of the target load 目 , and obtain the difference between U 目 and the preset reference voltage U ref , and then proceed to Step A2; Step A2. For U 目 The difference between U and ref is PI adjusted to obtain the duty cycle D of the inverter switch tube drive signal S , and then go to Step A3; Step A3. Based on the output voltage U of the AC side of the inverter at the transmitter S At the duty cycle D = D of the driving signal of the inverter switch tube S Perform Taylor expansion at this point, according to the following formula: Obtain the control quantity G1(S) of the output voltage on the AC side of the inverter; Meanwhile, according to the following formula: Obtain the interference quantity G2(S) of the output voltage on the AC side of the inverter, and then enter step A4; Step A4. According to the following formula: Obtain the output voltage U of the AC side of the inverter at the transmitting end S , and then proceed to step A5; Step A5. Based on the inverter operating at the operating frequency f O = f 目 to operate. The output voltage U of the AC side of the inverter S is wirelessly transmitted via the transmitting coil in the direction of the receiving coil in each receiving end connected to each load, and is received by each load with an operating frequency equal to f 目 via the receiving coil in its connected receiving end. The voltage across each load is stably controlled, and then return to Step A1; Based on the inverter including a first bridge arm and a second bridge arm connected in parallel, the first bridge arm includes a first switching tube Q1 and a second switching tube Q2 connected in series, and the second bridge arm includes a third switching tube Q3 and a fourth switching tube Q4 connected in series. The control method includes dual-frequency energy transfer control, which is carried out according to steps B1 to B5 as follows to achieve voltage control of the load; Step B1. Collect the actual voltage U of the specified first target load 目1 , the actual voltage U of the second target load 目2 , and the operating frequency f of the first target load 目1 , the operating frequency f of the second target load 目2 , and obtain the difference between U 目1 and the preset reference voltage U ref , as well as the difference between U 目2 and the preset reference voltage U ref , then proceed to Step B2; Step B2. For U 目1 and the difference between U ref , perform PI regulation to obtain the duty cycle D of the drive signals of the first switch Q1 and the second switch Q2 on the first leg of the inverter S1 , and for the difference between U 目2 and U ref , perform PI regulation to obtain the duty cycle D of the drive signals of the third switch Q3 and the fourth switch Q4 on the second leg of the inverter S2 , and then proceed to Step B3; Step B3. Based on k = 1, 2, according to the output voltage of the corresponding k-th target load on the AC side of the inverter at the transmitting end At the duty cycle D of the driving signal of the switching tube of the k-th bridge arm of the inverter Ok = D Sk Perform Taylor expansion at this point according to the following formula: Obtain the control quantity of the output voltage corresponding to the k-th target load on the AC side of the inverter Meanwhile, according to the following formula: Obtain the interference amount of the output voltage corresponding to the k-th target load on the AC side of the inverter Then enter step B4; Step B4. According to the following formula: Obtain the output voltage of the AC side of the inverter corresponding to the k-th target load at the transmitting end Then enter step B5; Step B5. Based on each switching tube on the first bridge arm in the inverter operating at the operating frequency f O1 = f 目1 to operate, the output voltage on the AC side of the inverter is wirelessly transmitted via the transmitting coil in the direction of the receiving coils in the receivers respectively connected to each load, and is received by each load with an operating frequency equal to f 目1 via the receiving coils in the receivers respectively connected to it, and the voltages across each load are stably controlled; Meanwhile, based on the switching tubes on the second bridge arm in the inverter operating at the operating frequency f O2 = f 目2 The output voltage U of the AC side of the inverter S (2) is wirelessly transmitted in the direction of the receiving coils in the receivers respectively connected to each load through the transmitting coil, and is received by each load with an operating frequency equal to f 目2 through the receiving coils in the receivers respectively connected to it, and the voltage across each load is stably controlled; then return to step B1.

2. The multi - frequency and multi - load wireless power transfer control method according to claim 1, wherein: In the inductive wireless connection between the transmitting end and the receiving ends respectively connected to each load, the transmitting end further includes an LCC compensation network, and the inverter further includes diodes corresponding to the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 respectively. In the structure of the transmitting end: the drains of the switches in the inverter are connected to the cathodes of the corresponding diodes, and the sources of the switches are connected to the anodes of the corresponding diodes; the positive electrode of the DC power supply V in , the drain of the first switch Q1, and the drain of the third switch Q3 are connected together, and the negative electrode of the DC power supply V in , the source of the second switch Q2, and the source of the fourth switch Q4 are connected together; The source electrode of the first switching transistor Q1 is connected to the drain electrode of the second switching transistor Q2, and the connection end is connected to one end of the series inductor L in the LCC type compensation network. p One end of the source electrode of the third switching transistor Q3 is connected to one end of the drain electrode of the fourth switching transistor Q4, and the connection end is connected to one end of the parallel compensation capacitor C in the LCC type compensation network, one end of the internal resistance R in the transmitting coil. P One end of the source electrode of the third switching transistor Q3 is connected to one end of the drain electrode of the fourth switching transistor Q4, and the connection end is connected to one end of the parallel compensation capacitor C in the LCC type compensation network, one end of the internal resistance R in the transmitting coil. T One end of the series inductor L in the LCC type compensation network. p The other end of the series inductor L in the LCC type compensation network, the other end of the parallel compensation capacitor C in the LCC type compensation network, and one end of the compensation capacitor C in the transmitting coil are butted against each other. P One end of the compensation capacitor C in the transmitting coil. T One end of the compensation capacitor C in the transmitting coil. T The other end of the compensation capacitor C in the transmitting coil is butted against one end of the transmitting coil inductor L. T One end of the internal resistance R in the transmitting coil. T The other end of the internal resistance R in the transmitting coil is butted against the other end of the transmitting coil inductor L. T The other end of the transmitting coil inductor L. T The transmitting coil inductor L is wirelessly connected to the receiving coil inductor L in the receiving end connected to each load, where m = {1,..., n}, and n represents the number of all loads. m The transmitting coil inductor L is wirelessly connected to the receiving coil inductor L in the receiving end connected to each load, where m = {1,..., n}, and n represents the number of all loads. The structures of the receivers connected to each load are the same as each other, and each receiver further includes a rectifier and a filter capacitor C fm , in the structure of each receiver: the receiving coil inductance L m One end of which is connected to one end of the receiving coil compensation capacitor C m , the other end of the receiving coil inductance L m is connected to one end of the internal resistance R of the receiving coil m ; the other end of the internal resistance R of the receiving coil m is connected to one end of the AC side of the rectifier, and the other end of the receiving coil compensation capacitor C m is connected to the other end of the AC side of the rectifier; one end of the DC side of the rectifier is connected to one end of the filter capacitor C fm , and the connected end is connected to one end of the corresponding load; the other end of the DC side of the rectifier is connected to the other end of the filter capacitor C fm , and the connected end is connected to the other end of the corresponding load.

3. The multi - frequency and multi - load wireless power transfer control method according to claim 2, characterized in that: In the single-frequency energy transmission control, the output voltage U of the AC side of the inverter S In the wireless transmission state in the direction of the receiving coil in the receiving end respectively connected to each load through the transmitting coil, according to the following formula: Obtain the load equivalent resistance R referred to the AC side of the rectifier in each receiving end to which the loads are connected Leqm , where R Leqm represents the load equivalent resistance referred to the AC side of the rectifier in the receiving end to which the m-th load is connected, and R Lm represents the resistance of the m-th load; then according to the following formula: Obtain the impedance Z of each receiving end m , where Z m represents the impedance of the receiving end connected to the m-th load, ω o represents the operating angular frequency of the inverter, l is the imaginary unit, L m represents the receiving coil inductance of the receiving end connected to the m-th load, C m represents the receiving coil compensation capacitor of the receiving end connected to the m-th load, R m represents the internal resistance of the receiving coil of the receiving end connected to the m-th load; Then, based on the mutual inductance between the receiving coils of each receiver being 0, according to the following formula: Successively obtain the reflected impedance Z ref and the equivalent input impedance Z S , where M Tm represents the mutual inductance between the transmitting coil and the receiving coil connected to the m-th load, and / / represents the parallel relationship formed between two objects; Finally, based on j representing the sequence number of each load in the controlled sorting of each load with the same operating frequency as the target load, according to the following formula: Obtain the voltage gain K received by each load having the same operating frequency as the target load j (ω o )R Leqj , where R Leqj represents the load equivalent resistance referred to the AC side of the rectifier in the receiver connected to the j-th load in the controlled sorting, and K j (ω o )R Leqj represents the voltage gain received by the j-th load in the controlled sorting, Z j represents the impedance of the receiver connected to the j-th load in the controlled sorting, and M Tj represents the mutual inductance between the transmitting coil and the coil connected in the receiver connected to the j-th load in the controlled sorting.

4. The multi-frequency and multi-load wireless power transmission control method according to claim 2, wherein: In the dual-frequency energy transmission, the output voltage of the AC side of the inverter In the wireless transmission state in the direction of the receiving coil in the receiving end respectively connected to each load through the transmitting coil, and the output voltage of the AC side of the inverter In the wireless transmission state in the direction of the receiving coil in the receiving end respectively connected to each load through the transmitting coil, according to the following formula: Obtain the load equivalent resistance R referred to the AC side of the rectifier in each receiving end to which the loads are connected Leqm , where R Leqm represents the load equivalent resistance referred to the AC side of the rectifier in the receiving end to which the m-th load is connected, and R Lm represents the resistance of the m-th load; then according to the following formula: Obtain the impedance of the k-th target load corresponding to each receiving end Among them, represents the impedance of the receiving end connected to the m-th load corresponding to the k-th target load, ω ok represents the operating angular frequency of the switching tube of the k-th bridge arm of the inverter, l is the imaginary unit, L m represents the inductance of the receiving coil of the receiving end connected to the m-th load, C m represents the compensation capacitor of the receiving coil of the receiving end connected to the m-th load, R m represents the internal resistance of the receiving coil of the receiving end connected to the m-th load; Then, based on the mutual inductance between the receiving coils of each receiver being 0, according to the following formula: Successively obtain the reflection impedance corresponding to the k-th target load The equivalent input impedance corresponding to the k-th target load where M Tm represents the mutual inductance between the transmitting coil and the receiving coil connected to the m-th load, and / / represents the parallel relationship formed between the two objects; Finally, based on e representing the sequence number of each load in the first controlled sorting of each load with the same operating frequency as the first target load, and g representing the sequence number of each load in the second controlled sorting of each load with the same operating frequency as the second target load, according to the following formula: Obtain the voltage gains received by each load having the same operating frequency as the first target load wherein, R Leqe represents the load equivalent resistance referred to the AC side of the rectifier in the receiver connected to the e-th load in the first controlled sorting order, represents the voltage gain received by the e-th load in the first controlled sorting order, represents the impedance of the receiver connected to the e-th load in the first controlled sorting order, M Te represents the mutual inductance between the transmitting coil and the receiving coil in the receiver connected to the e-th load in the first controlled sorting order; and obtain the voltage gain received by each load having the same operating frequency as the second target load wherein, R Leqg represents the load equivalent resistance referred to the AC side of the rectifier in the receiver connected to the g-th load in the second controlled sorting represents the voltage gain received by the g-th load in the second controlled sorting represents the impedance of the receiver connected to the g-th load in the second controlled sorting, M Tg represents the mutual inductance between the transmitting coil and the receiving coil in the receiver connected to the g-th load in the second controlled sorting

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