CN105958667A - Maximum efficiency point tracking method for bidirectional wireless electric energy transmission system - Google Patents

Abstract

The invention provides a maximum efficiency point tracking method for a bidirectional wireless electric energy transmission system. The maximum efficiency point tracking method includes the steps: replacing the resonant capacitors at the primary side and the secondary side of the bidirectional wireless electric energy transmission system as vacuum adjustable capacitors, and respectively connecting with one stepping motor; after the bidirectional wireless electric energy transmission system achieves the maximum transmission efficiency, and when a coupling coil offsets, by means of coaxial rotation of the stepping motors and the vacuum adjustable capacitors, adjusting the capacitance of the vacuum adjustable capacitors so as to adjust the resonant frequency of a system resonant cavity; and changing the switching frequency of converters at two sides at the same time to enable the switching frequency of the converters to be consistent with the resonant frequency of the resonant cavity so as to finally improve the system frequency to overcome the problem that the maximum efficiency is reduced.

Description

A kind of maximal efficiency point-tracking method of bidirectional radio energy transmission system

Technical field

The present invention relates to wireless power transmission field, the pressure point of maximum efficiency of a kind of bidirectional radio energy transmission system with Track method.

Background technology

At bidirectional radio energy transmission field, between both sides, carry out interactive worth research with how realizing energy efficient.Mesh Before the method such as using low-loss material coiling resonance coil has occurred to promote system effectiveness.Meanwhile, reasonable disposition is primary Side converter exit potential and primary side changer exit potential are also a kind of methods optimizing system transfers efficiency.But, In some cases, the coupling coil of both sides can occur dislocation thus causes its coupling factor to reduce and hence in so that optimize Efficiency reduces.How to use simple method to realize bidirectional radio energy transmission system pressure point of maximum efficiency to be tracked Urgently study, but the method at present solution of this problem also not occurred.

Summary of the invention

Goal of the invention: for solving to cause it to couple in bidirectional radio energy transmission system because coupling coil can occur to misplace Factor reduces and hence in so that the technical problem that reduces of the efficiency that optimizes, and the present invention provides a kind of bidirectional radio energy transmission system The maximal efficiency point-tracking method of system.

Technical scheme: for solving above-mentioned technical problem, the technical scheme that the present invention proposes is:

A kind of maximal efficiency point-tracking method of bidirectional radio energy transmission system, described bidirectional radio energy transmission system bag Include the symmetrical primary side of topological structure and primary side；Primary side includes power supply I, controller I, changer I and a LCL Resonant network；Primary side includes power supply II, controller II, changer II and the 2nd LCL resonant network；Oneth LCL The first resonant capacitance in resonant network and the second resonant capacitance in the 2nd LCL resonant network are vacuum tunable capacitor Device, the connection coaxial with the outfan of first, second motor respectively of the adjustable side of first, second resonant capacitance, pass through Motor and the coaxial rotation of vacuum adjustable condenser, the capacitance of the corresponding vacuum adjustable condenser of regulation, to change system The resonant frequency of resonator cavity；Described maximal efficiency point-tracking method includes step:

(1) adjust primary side and the controller of primary side, make the output voltage amplitude phase of primary side and primary side changer Deng, phase contrast is 90 °；Efficiency of transmission in the most described bidirectional radio energy transmission system reaches maximum, calculates and passes Defeated maximum efficiency；When primary side converter output voltage is ahead of primary side changer output voltage, the flowing of electric energy Direction is that primary side is to primary side；When primary side changer output voltage is ahead of primary side changer output voltage, electricity The flow direction of energy is that primary side is to primary side.

(2) when described bidirectional radio energy transmission system occurs that coupling coil misplaces, by first, second stepping electricity Machine regulates the capacitance of first, second resonant capacitance so that the efficiency of transmission in described bidirectional radio energy transmission system is protected Hold the efficiency of transmission maximum calculated in step (1)；

(3) while step (2) is carried out, opening of two side converters is regulated by the controller of primary side and primary side Close frequency, make the switching frequency of two side converters protect with the resonant frequency of resonator cavity in described bidirectional radio energy transmission system Hold consistent.

Further, described changer I and changer II is unidirectional full-bridge variable ratio frequency changer changer.

Further, in described step (1), the method for the output voltage amplitude of regulation primary side and primary side changer is:

The output voltage of primary side changer I is controlled by the driving pulse angle overlap adjusting primary side middle controller I output Amplitude；

The output electricity of primary side changer II is controlled by the driving pulse angle overlap adjusting primary side middle controller II output Pressure amplitude value so that it is equal with the output voltage amplitude of primary side changer I, and phase contrast is 90 °.

Beneficial effect: compared with prior art, the present invention provide method possess bidirectional radio energy transmission system be in During maximum transmitted efficient point, the method being improved the resonant frequency of system by the resonant capacitance of regulation both sides, overcome due to line The problem that the system maximal efficiency enclosing the uncertainties such as dislocation and cause reduces.The method is simple, and has compensation essence Spend high feature, it is possible to realize the quick tracking of bidirectional radio energy transmission system maximum power point.

Accompanying drawing explanation

Fig. 1 is that bidirectional radio energy transmits system topological figure；

Fig. 2 is motor and vacuum tunable capacitor coaxial construction figure；

Fig. 3 is vacuum tunable capacitor capacitance curve chart.

Detailed description of the invention

Below in conjunction with the accompanying drawings the present invention is further described.

The present invention provides the maximal efficiency point-tracking method of a kind of bidirectional radio energy transmission system, is illustrated in figure 1 two-way Radio energy transmission system topological diagram, this system includes primary side and the primary side that topological structure is symmetrical；Wherein, primary side Including power supply I, controller I, changer I and a LCL resonant network；Primary side include power supply II, controller II, Changer II and the 2nd LCL resonant network.Changer I and changer II is unidirectional full-bridge variable ratio frequency changer changer, conversion Device I is made up of switching tube S1～S4, and changer II is made up of switching tube S5～S8；Oneth LCL resonant network includes string Connection resistance R1, R2, series inductance Lm, resonant inductance L11 and resonant capacitance C1；2nd LCL resonant network includes Series resistance R3, R4, series inductance Ln, resonant inductance L21 and resonant capacitance C2.Power supply I passes through changer I Being connected with a LCL resonant network, the break-make of switching tube S1～S4 is controlled by controller I；Power supply II passes through changer II and the 2nd LCL resonant network are connected, and the break-make of switching tube S5～S8 is controlled by controller II；Resonant capacitance C1, C2 Be vacuum tunable capacitor, the capacitance adjustable side of C1, C2 respectively with the first, second coaxial connection of motor, as Shown in Fig. 2.

In the circuit topology of the bidirectional radio energy transmission system shown in Fig. 1, C1=C2=C, R1=R2=R3=R4=R, L1=L11=L21=L2=L, the frequency range of single-phase full bridge variable ratio frequency changer changer is f_min～f_max；Primary side is with secondary The capacitance curve chart of the resonant capacitance of level side is as it is shown on figure 3, excursion is C_min～C_max.Initialization system the most humorous Vibration frequency is f₀, and meet f_min≤1/2πsqrt(LC_max)≤f₀1/2πsqrt(LC_min)≤≤f_max.System both sides humorous The initial coupling factor of device of shaking is k₀, now the efficiency of transmission of system reaches maximum.

The control principle of the present invention is as follows:

When the controller of both sides controls the output voltage amplitude of full-bridge variable ratio frequency changer changer unanimously, system when phase contrast is 90 ° Efficiency of transmission maximum, when primary side converter output voltage phase place is ahead of primary side changer output voltage phase place, The flow direction of electric energy is that primary side is to primary side；When primary side changer output voltage phase place is ahead of primary side changer During output voltage phase place, the flow direction of electric energy is that primary side is to primary side.

The efficiency of transmission maximum of system is:

${\mathrm{\η}}_{f-opt}={\mathrm{\η}}_{i-opt}=\frac{\frac{{\mathrm{\λ}}_2}{{\mathrm{\λ}}_1}-1}{\frac{{\mathrm{\λ}}_2}{{\mathrm{\λ}}_1}+1}---\left(1\right)$

Wherein: η_f-optFor electric energy maximum transmitted efficiency, η when primary side flows to primary side_i-optFlow to from primary side for electric energy Maximum transmitted efficiency during primary side.Wherein, λ₁=ω⁶C⁴M²R+ω⁴C⁴R³+ω²C²R, λ₂=ω³C²M.M represents Primary side and the mutual inductance of primary side coupling coil, ω is phase angle speed.

Now, the maximal efficiency factor is λ₂/λ₁,

$\frac{{\mathrm{\λ}}_2}{{\mathrm{\λ}}_1}=\sqrt{\frac{k^2{Q}^6}{Q^4{k}^4+2Q^2(Q^2+1)k^2+{(Q^2+1)}^2}}---\left(2\right)$

Wherein, k is the coupling factor of primary side and primary side, by formula (2) approximate processing is:

$\frac{{\mathrm{\λ}}_2}{{\mathrm{\λ}}_1}=\sqrt{\frac{k^2{Q}^6}{Q^4{k}^4+2Q^4{k}^2+Q^4}}---\left(3\right)$

During energy is wirelessly transferred, when certain external factor causes coupling coil to misplace, the primary side of system is utilized to control Device calculates coupling factor k now_mis, in order to keep the maximal efficiency factor constant, necessarily have:

$\frac{{k_0}^2{Q_0}^6}{{Q_0}^4{k_0}^4+2{Q_0}^4{k_0}^2+{Q_0}^4}=\frac{{k_{mis}}^2{Q_{mis}}^6}{{Q_{mis}}^4{k_{mis}}^4+2{Q_{mis}}^4{k_{mis}}^2+{Q_{mis}}^4}---\left(4\right)$

Correspondingly:

$\frac{Q_0}{Q_{mis}}=\sqrt{T\frac{{k_0}^2+\frac{1}{{k_0}^2}+2}{{k_{mis}}^2+\frac{1}{{k_{mis}}^2}+2}}---\left(5\right)$

In formula, Q is the quality factor of coil, Q₀For initial quality factor, Q₀=2 π f₀L/R；Q_misFor there is certain When external factor causes coupling coil to misplace will constant required quality factor of the maximal efficiency factor in holding system, Q_mis=2 π f₁L/R.Due to k_mis＜ k₀＜ 1, therefore, Q_mis＞ Q₀, the most now need to improve f₀To f₁.Profit Coupling factor k now is calculated with the controller of system_mis, and simultaneously the control of relevant parameter input to motor Device, drive stepping motor rotate reduction capacitance coaxial with vacuum tunable capacitor, the resonant frequency of lifting resonator cavity to f₁。 Treat that the resonant frequency of both sides resonator cavity is stable at f₁Time, then regulate the switch lock of both sides single-phase full bridge variable ratio frequency changer changer simultaneously Rate is to f₁, continued the transmission of energy.

Based on above-mentioned control principle, the maximal efficiency point-tracking method of the bidirectional radio energy transmission system that the present invention provides is held Row step is as follows:

(1) adjust primary side and the controller of primary side, make the output voltage amplitude phase of primary side and primary side changer Deng, phase contrast is 90 °；Efficiency of transmission in the most described bidirectional radio energy transmission system reaches maximum, calculates and passes Defeated maximum efficiency；

(2) when described bidirectional radio energy transmission system occurs that coupling coil misplaces, by first, second stepping electricity Machine regulates the capacitance of first, second resonant capacitance so that the efficiency of transmission in described bidirectional radio energy transmission system is protected Hold the efficiency of transmission maximum calculated in step (1)；

(3) while step (2) is carried out, opening of two side converters is regulated by the controller of primary side and primary side Close frequency, make the switching frequency of two side converters protect with the resonant frequency of resonator cavity in described bidirectional radio energy transmission system Hold consistent.

The above is only the preferred embodiment of the present invention, it should be pointed out that: for those skilled in the art For, under the premise without departing from the principles of the invention, it is also possible to make some improvements and modifications, these improvements and modifications are also Should be regarded as protection scope of the present invention.

Claims (3)

1. the maximal efficiency point-tracking method of a bidirectional radio energy transmission system, it is characterised in that described two-way nothing Line electric energy transmission system includes primary side and the primary side that topological structure is symmetrical；Primary side includes power supply I, controller I, change Parallel operation I and a LCL resonant network；Primary side includes that power supply II, controller II, changer II and the 2nd LCL are humorous Vibrating network；The first resonant capacitance in oneth LCL resonant network and the second resonant capacitance in the 2nd LCL resonant network Be vacuum adjustable condenser, the adjustable side of first, second resonant capacitance respectively with the output of first, second motor Hold coaxial connection, by motor and the coaxial rotation of vacuum adjustable condenser, the corresponding vacuum adjustable condenser of regulation Capacitance, to change the resonant frequency in system resonance chamber；Described maximal efficiency point-tracking method includes step:

(1) adjust primary side and the controller of primary side, make the output voltage amplitude phase of primary side and primary side changer Deng, phase contrast is 90 °；Efficiency of transmission in the most described bidirectional radio energy transmission system reaches maximum, calculates and passes Defeated maximum efficiency；

(2) when described bidirectional radio energy transmission system occurs that coupling coil misplaces, by first, second stepping electricity Machine regulates the capacitance of first, second resonant capacitance so that the efficiency of transmission in described bidirectional radio energy transmission system is protected Hold the efficiency of transmission maximum calculated in step (1)；

(3) while step (2) is carried out, opening of two side converters is regulated by the controller of primary side and primary side Close frequency, make the switching frequency of two side converters protect with the resonant frequency of resonator cavity in described bidirectional radio energy transmission system Hold consistent.

The maximal efficiency point-tracking method of a kind of bidirectional radio energy the most according to claim 1 transmission system, its Being characterised by, described changer I and changer II is unidirectional full-bridge variable ratio frequency changer changer.

The maximal efficiency point-tracking method of a kind of bidirectional radio energy the most according to claim 1 transmission system, its Being characterised by, in described step (1), the method for the output voltage amplitude of regulation primary side and primary side changer is:

The output voltage of primary side changer I is controlled by the driving pulse angle overlap adjusting primary side middle controller I output Amplitude；

The output electricity of primary side changer II is controlled by the driving pulse angle overlap adjusting primary side middle controller II output Pressure amplitude value so that it is equal with the output voltage amplitude of primary side changer I, and phase contrast is 90 °.