CN103441581B - IPT system primary power regulation method and system based on controllable inductance - Google Patents

Abstract

The invention provides an IPT system primary power regulation method and system based on controllable inductance. The power regulation method comprises the following steps that a voltage type IPT system is established, a primary resonance inductor comprises a coil of N turns, the Nth turn of the coil is connected with a coil control switch Kn in series, equivalent load impedance values and primary resonance inductor optimal values are preset in a controller, and the equivalent load impedances and the primary resonance inductance optimal values correspond to each other one by one; the controller works out the equivalent load impedance value and obtains the primary resonance inductance optimal value according to the corresponding relation between the equivalent load impedance values and the primary resonance inductance optimal values, and controls switching-on and switching-off of the coil control switch Kn, and therefore regulation of the primary resonance inductor is achieved. By the adoption of the IPT system primary power regulation method and system based on the controllable inductance, the number of the turns of the coil which is connected to a circuit is adjusted according to the load, and the primary resonance inductance and the effective area and the magnetic flow area which exist in the process of practical work of the primary coil are regulated according to the load; when the IPT system works at different loads, the IPT system can achieve the optimal system efficiency and electromagnetic radiation is reduced to the maximum extent.

Description

A kind of IPT system former limit power regulating method based on controlled inductance and system

Technical field

The present invention relates to IPT(Inductively Power Transfer, induction electric energy transmits) power conditioning technology of system, be specifically related to a kind of IPT system former limit power regulating method based on controlled inductance and system.

Background technology

IPT technology has started plant-grid connection new paragon, receives the concern of academia more and more widely, has become the study hotspot of electrical field.There is one of the IPT system general power supply platform of stronger practicality important application direction current just.General purpose I PT system power supply platform has a road energy transmitter structure (former limit) and multichannel mechanism for picking (secondary) and power consumption equipment, and wherein each road mechanism for picking is all installed in corresponding power consumption equipment, and different power consumption equipment has different capacity grade.When different capacity grade load (power consumption equipment) switches, the parameter of IPT system, the reflected umpedance, coupling coefficient etc. of such as secondary to former limit can change, thus the efficiency of transmission of influential system, corresponding measure need be taked to guarantee system high efficiency stable operation when therefore load switches.

In existing IPT system, a kind of method is had to be size by control system former limit capacitor array and control system efficiency of transmission, as shown in Figure 1, its operation principle is that former limit resonant circuit is connected with frequency detector, the input of this frequency detector is connected between former limit resonant capacitance and excitation coil, its output exports the first input end of former limit resonant frequency value f1 to controller, second input input system setting resonant frequency value f0 of this controller, the output control terminal of controller is connected with shunt capacitance array, this shunt capacitance array in parallel is on the resonant capacitance of former limit, controller controls the capacitance of shunt capacitance array according to f1 and f0.In this control method, when the bearing power grade of IPT system is on a large scale during change, the capacitor array on former limit must be made up of a large amount of electric capacity, and each electric capacity is all connected with control switch, this considerably increases the volume of circuit.In addition, IPT system works is in high frequency mode, the major issue must considered when electromagnetic radiation is household electric appliance operation, because the volume of different power consumption equipment varies in size, if make the size of former edge emitting coil immobilize, during the less loaded work piece of base area, primary coil will produce larger electromagnetic radiation, and this condenser network control method does not consider the electromagnetic radiation of system to surrounding environment.

Summary of the invention

In order to overcome the defect existed in above-mentioned prior art, the object of this invention is to provide a kind of IPT system former limit power regulating method based on controlled inductance and system, can accurately identify IPT system load and according to the inductance value of load adjustment primary coil real work and effective area, reduce the waste of former limit energy, the efficiency optimization of system can be realized, electromagnetic radiation can be reduced to greatest extent again.

In order to realize above-mentioned purpose of the present invention, according to a first aspect of the invention, the invention provides a kind of IPT system former limit power regulating method based on controlled inductance, comprise the steps:

S1: set up voltage-type IPT system, described voltage-type IPT system is made up of former limit circuit and secondary circuit;

Described former limit circuit is provided with full-bridge inverter, the power end of described full-bridge inverter connects DC power supply, output and former limit resonant inductance Lp, former limit building-out capacitor Cp are connected to form a series loop, described former limit building-out capacitor Cp comprises the first electric capacity C1 in parallel and the second electric capacity C2, described second electric capacity C2 is connected by capacitance selection switch S control realization and cuts off, described capacitance selection switch S is connected with controller, by the break-make of controller control capacitance selector switch S;

Equivalent load impedance and former limit resonant inductance optimal value is one to one preset with in described controller, described former limit resonant inductance optimal value be former limit building-out capacitor Cp be the first electric capacity C1, former limit power stage efficiency meet design requirement time, corresponding to the inductance value of described equivalent load impedance;

Described former limit resonant inductance Lp comprises N circle coil, and described n-th circle coils connected in series has a coil control switch Kn, and described coil control switch Kn is connected with described controller, by controller control realization break-make, wherein, described N is positive integer, described n=1,2 ..., N-1, N;

Described former limit circuit is also provided with current sensing means, described current sensing means is connected with described former limit resonant inductance Lp, described current sensing means is also connected with described controller, and described current sensing means is for detecting electric current in described former limit resonant inductance Lp and by described current delivery to described controller;

Described secondary circuit comprises at least one secondary electronic circuit, and described m secondary electronic circuit is by secondary resonant inductance Ls, secondary building-out capacitor Cs, load impedance Z _lmcomposition, described secondary resonant inductance Ls, secondary building-out capacitor Cs and load impedance Z _lmthree is connected to form a series loop successively, and at synchronization, only have the work of a secondary electronic circuit, described m is positive integer;

S2: controller cuts off capacitance selection switch S, and make the first electric capacity C1 access former limit circuit, DC power supply carries out direct current supply to former limit circuit, makes described former limit circuit enter resonance condition;

S3: current sensing means detects the electric current of former limit circuit and by described current delivery to described controller, described controller obtains the first effective value and first operating frequency of described former limit circuital current;

S4: controller closes electric capacity selector switch S, access former limit circuit after making the first electric capacity C1 and the second electric capacity C2 parallel connection, DC power supply carries out direct current supply to former limit circuit, and controller regulates the operating frequency of inverter to make former limit circuit enter resonance condition;

S5: current sensing means detects the electric current of former limit circuit and by described current delivery to described controller, described controller obtains the second effective value and second operating frequency of described former limit circuital current;

S6: controller sets up impedance equation according to the first effective value of described former limit circuital current, the second effective value and corresponding operating frequency, asks for equivalent load impedance Z _l;

S7: controller cuts off capacitance selection switch S, and make the first electric capacity C1 access former limit circuit, described controller is according to equivalent load impedance Z _lvalue, the corresponding relation according to equivalent load impedance and former limit resonant inductance optimal value obtains the optimal value of former limit resonant inductance, and the conducting of control coil control switch Kn and cut-out, realizes the adjustment of former limit resonant inductance.

The present invention is by changing the size of former limit building-out capacitor, under making former limit be operated in two kinds of different resonance frequencys, by setting up reflected umpedance equation, realize load accurately to identify, meanwhile, according to the coil turn of limit, the size adjustment place in circuit Central Plains circuit of load, regulate the size of former limit resonant inductance and the effective area of coil real work and magnetic flux area, when different loads works, make IPT system can realize the efficiency optimization of system, electromagnetic radiation can be reduced to greatest extent again.

In order to realize above-mentioned purpose of the present invention, according to a second aspect of the invention, the invention provides a kind of IPT system former limit power regulating system based on controlled inductance, comprise voltage-type IPT system and controller, described voltage-type IPT system is made up of former limit circuit and secondary circuit, described former limit circuit is provided with full-bridge inverter, the power end of described full-bridge inverter connects DC power supply, output and former limit resonant inductance Lp, former limit building-out capacitor Cp are connected to form a series loop, described former limit building-out capacitor Cp comprises the first electric capacity C1 in parallel and the second electric capacity C2, described second electric capacity C2 is connected by capacitance selection switch S control realization and cuts off, described capacitance selection switch S is connected with controller, by the break-make of controller control capacitance selector switch S, equivalent load impedance and former limit resonant inductance optimal value is one to one preset with in described controller, described former limit resonant inductance Lp comprises N circle coil, and described n-th circle coils connected in series has a coil control switch Kn, and described coil control switch Kn is connected with described controller, by controller control realization break-make, wherein, described N is positive integer, described n=1,2 ..., N-1, N, described former limit circuit is also provided with current sensing means, described current sensing means is connected with described former limit resonant inductance Lp, described current sensing means is also connected with described controller, and described current sensing means is for detecting electric current in described former limit resonant inductance Lp and by described current delivery to described controller, described secondary circuit comprises at least one secondary electronic circuit, and each secondary electronic circuit described is by secondary resonant inductance Ls, secondary building-out capacitor Cs, load impedance Z _lmcomposition, described secondary resonant inductance Ls, secondary building-out capacitor Cs and load impedance Z _lmthree is connected to form a series loop successively, at synchronization, only has the work of a secondary electronic circuit, described current sensing means comprises resonance current frequency detecting unit, resonance current effective value sampling unit and resonance current over-zero sampling unit, described resonance current frequency detecting unit is for detecting the resonance frequency of primary current, and described resonance current effective value sampling unit and resonance current over-zero sampling unit carry out effective value sampling and current over-zero sampling to the current waveform of former limit circuit respectively, the input of described controller is connected with the output of described current sensing means, described controller comprises frequency adjustment unit, remained capacity unit and inductance control unit, the output of described resonance current zero passage sampling unit is connected with the input of described frequency adjustment unit, the output of described frequency adjustment unit is connected with full-bridge inverter, the electric voltage frequency that described frequency adjustment unit regulates full-bridge inverter to export according to the current zero-crossing signal of described resonance current zero passage sampling unit collection makes former limit circuit enter resonance condition, described remained capacity unit is connected with resonance current effective value sampling unit with described resonance current frequency detecting unit respectively, for setting up impedance equation, load is identified, described inductance control unit is connected with described remained capacity unit, described inductance control unit is also connected with coil control switch Kn respectively, be preset with equivalent load impedance and former limit resonant inductance optimal value one to one in described inductance control unit, described inductance control unit is according to equivalent load impedance Z _lvalue, the corresponding relation according to described equivalent load impedance and former limit resonant inductance optimal value obtains the optimal value of former limit resonant inductance, and the conducting of control coil control switch Kn and cut-out, and the optimal value realizing former limit resonant inductance regulates.

IPT system former limit power regulating system based on controlled inductance of the present invention can realize the accurate detection of load, and pass through according to the value of load the coil turn that coil control switch Kn controls limit, place in circuit Central Plains circuit, regulate the size of former limit resonant inductance and the effective area of coil real work and magnetic flux area, when different loads works, make IPT system can realize the efficiency optimization of system, electromagnetic radiation can be reduced to greatest extent again.

In the preferred embodiment of the present invention, the described impedance equation set up according to the first effective value, the second effective value and corresponding operating frequency is:

$\mathrm{Im}{Z}_L=\frac{\mathrm{Im}{\mathrm{Zr}}_1\×(u_P-I_{P2}{R}_P)\×I_{P1}\×({\mathrm{\ω}}_2{L}_S-1/{\mathrm{\ω}}_2{C}_S)-\mathrm{Im}{\mathrm{Zr}}_2\×(u_P-I_{P1}{R}_P)\×I_{P2}\×({\mathrm{\ω}}_1{L}_S-1/{\mathrm{\ω}}_1{C}_S)}{\mathrm{Im}{\mathrm{Zr}}_2\×(u_P-I_{P1}{R}_P)\×I_{P2}-\mathrm{Im}{\mathrm{Zr}}_1\×(u_P-I_{P2}{R}_P)\×I_{P1}}$

$\mathrm{Re}{Z}_L=\frac{(u_P-I_{P2}{R}_P)\×(1/{\mathrm{\ω}}_2{C}_S-{\mathrm{\ω}}_2{L}_S-\mathrm{Im}{Z}_L)}{\mathrm{Im}{\mathrm{Zr}}_2\×I_{P2}}$

ImZ _r1+ω ₁L _P-1ω ₁C ₁＝0

$\mathrm{Im}{Z}_{r2}+{\mathrm{\ω}}_2{L}_P-\frac{1}{{\mathrm{\ω}}_2(C_1+C_2)}=0$

Wherein, Rp is primary coil internal resistance and electric capacity internal resistance, and Rs is secondary coil internal resistance, u _pfor the voltage that inverter bridge exports, I _p1for with former limit circuit first effective value, I _p2for former limit circuit second effective value, w ₁for only have first electric capacity C1 cut circuit time former limit resonance frequency, w ₂it is the resonance frequency on the first electric capacity C1 and the second electric capacity C2 former limit when all cutting circuit.The present invention, by setting up impedance equation, accurately can identify load.

In another kind of preferred implementation of the present invention, described former limit circuit is also provided with current transformer, described current transformer is for obtaining the current waveform of former limit circuit resonance state, and the output of described current transformer is connected with the input of resonance current over-zero sampling unit with described resonance current frequency detecting unit, described resonance current effective value value sampling unit.Realize the detection of former limit circuital current safely and reliably.

Additional aspect of the present invention and advantage will part provide in the following description, and part will become obvious from the following description, or be recognized by practice of the present invention.

Accompanying drawing explanation

Above-mentioned and/or additional aspect of the present invention and advantage will become obvious and easy understand from accompanying drawing below combining to the description of embodiment, wherein:

Fig. 1 is the circuit theory diagrams based on the power regulating system of capacitor array in prior art;

Fig. 2 is the circuit theory diagrams of SS voltage-type IPT system in a kind of preferred implementation of the present invention;

Fig. 3 is the structure chart of current sensing means and controller in a kind of preferred implementation of the present invention;

Fig. 4 is the flow chart of voltage-type wireless power supply system load identification method of the present invention.

Embodiment

Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Being exemplary below by the embodiment be described with reference to the drawings, only for explaining the present invention, and can not limitation of the present invention being interpreted as.

In describing the invention, unless otherwise prescribed and limit, it should be noted that, term " installation ", " being connected ", " connection " should be interpreted broadly, such as, can be mechanical connection or electrical connection, also can be the connection of two element internals, can be directly be connected, also indirectly can be connected by intermediary, for the ordinary skill in the art, the concrete meaning of above-mentioned term can be understood as the case may be.

The invention provides a kind of voltage-type wireless power supply system remained capacity system, as shown in Figure 2, it comprises voltage-type IPT system and controller, and wherein, voltage-type IPT system is made up of former limit circuit and secondary circuit.Former limit circuit is provided with full-bridge inverter, and the power end of full-bridge inverter connects DC power supply E _dCthe output of full-bridge inverter and former limit resonant inductance Lp, former limit building-out capacitor Cp are connected to form a series loop, as can be seen from Fig. 2, former limit building-out capacitor Cp comprises the first electric capacity C1 in parallel and the second electric capacity C2, second electric capacity C2 is connected by capacitance selection switch S control realization and cuts off, capacitance selection switch S is connected with controller, by the break-make of controller control capacitance selector switch S.

In the present embodiment, former limit resonant inductance Lp comprises N circle coil, and the n-th circle coils connected in series has a coil control switch Kn, and coil control switch Kn is connected with controller, and by controller control realization break-make, wherein, N is positive integer, n=1,2 ..., N-1, N.In the present embodiment, the controlled bidirectional switch pipe of each circle coils connected in series one of former limit resonant inductance Lp is as coil control switch Kn, when the load of different capacity grade or different volumes switches, by to the inductance value of break-make regulating and controlling former limit resonant inductance Lp of coil control switch Kn or the size of inductance effective area, in the present embodiment, according to bearing power grade design coil total number of turns, the inductance value of every circle coil can be designed by required precision.

In the present embodiment, former limit circuit is also provided with current sensing means, current sensing means is connected with former limit resonant inductance Lp, and current sensing means is also connected with controller, and current sensing means is for detecting electric current in former limit resonant inductance Lp and by current delivery to controller.

Secondary circuit comprises at least one secondary electronic circuit, and m secondary electronic circuit is by secondary resonant inductance Ls, secondary building-out capacitor Cs, load impedance Z _lmcomposition, secondary resonant inductance Ls, secondary building-out capacitor Cs and load impedance Z _lmthree is connected to form a series loop successively, at synchronization, only has the work of a secondary electronic circuit.

In the present embodiment, equivalent load impedance and former limit resonant inductance optimal value is one to one preset with in controller, this former limit resonant inductance optimal value be former limit building-out capacitor Cp be the first electric capacity C1, former limit power stage efficiency meet design requirement time, corresponding to the inductance value of equivalent load impedance.The relation of concrete equivalent load impedance and former limit resonant inductance can by following formulae discovery:

$\left\{\begin{array}{c}{Z}_s=\mathrm{j\ω}{L}_s+1/\mathrm{j\ω}{C}_s+Z_L\\ Z_r={\mathrm{\ω}}^2{M}^2/Z_s\\ Z_t=R_p+\mathrm{j\ω}{L}_p+1/\left(\mathrm{j\ω}{C}_p\right)+Z_r\end{array}---\left(1\right)\right.$

Wherein, M is the mutual inductance between coil, Rp is primary coil internal resistance and electric capacity internal resistance, Zr is the reflected umpedance of secondary energy pickup end equiva lent impedance Zs at former edge emitting end, Zt is former edge emitting end total impedance, make Im (Zt)=0 obtain the zero phase angle frequencies omega of system, the through-put power P of IPT system can be equivalent to the real part of reflected umpedance Zr and former limit resonance current Ip square product:

$P=\left(\mathrm{Re}{Z}_r\right)I_p^2---\left(2\right)$

IPT system effectiveness model can be obtained by formula (2):

$\mathrm{\η}=\frac{\left(\mathrm{Re}{Z}_r\right)I_p^2}{(\mathrm{Re}{Z}_r+R_p)I_p^2}=\frac{({\mathrm{\ω}}^2{M}^2/\mathrm{Re}{Z}_s)I_p^2}{({\mathrm{\ω}}^2{M}^2/\mathrm{Re}{Z}_s+R_p)I_p^2}=\frac{1}{1+\mathrm{Re}{Z}_s{R}_p/\left({\mathrm{\ω}}^2{M}^2\right)}---\left(3\right)$

Make the inductance of primary coil single-turn winding be La, the internal resistance of primary coil single-turn winding is Ra, then the inductance L p of primary coil and series equivalent impedance Rp is respectively:

L _P＝N ²L _a,R _p＝NR _a(4)

The above formula of simultaneous, can obtain the functional relation that voltage-type IPT system power efficiency of transmission η changes with former limit inductance L p.By the numerical solution of formula (3), obtain the load Z of different capacity grade _lwith the relation of the former limit resonant inductance Lp corresponding to system effectiveness.In the present embodiment, former limit resonant inductance optimal value is the first electric capacity C1 at former limit building-out capacitor Cp, and when former limit delivery efficiency meets job requirement, corresponding to the inductance value of secondary equivalent load impedance, it can be an inductance value, also can be an inductance range.

As shown in Figure 2, switch S 1-S4 form one work in Sofe Switch pattern under full-bridge inverter, direct current input E _dCby changing high-frequency alternating current u after inverter into _p, high-frequency alternating current u _pby producing high-frequency alternating magnetic field during transmitting terminal coil, secondary resonant inductance Ls interrogation energy from high-frequency alternating magnetic field, u in figure _pfor the square-wave voltage exported after inversion, I _sfor secondary loop electric current, Rs is secondary coil internal resistance.

As shown in Figure 3, in the present embodiment, current sensing means comprises resonance current frequency detecting unit, resonance current effective value sampling unit and resonance current over-zero sampling unit, resonance current frequency detecting unit is for detecting the resonance frequency of primary current, and resonance current effective value sampling unit and resonance current over-zero sampling unit carry out effective value sampling and current over-zero sampling to the current waveform of former limit circuit respectively.

Controller comprises frequency adjustment unit, remained capacity unit and inductance control unit, the output of resonance current zero passage sampling unit is connected with the input of frequency adjustment unit, output and full-bridge inverter four switches of frequency adjustment unit are connected (not illustrating in Fig. 2) respectively, the electric voltage frequency that frequency adjustment unit regulates full-bridge inverter to export according to the current zero-crossing signal of resonance current zero passage sampling unit collection makes former limit circuit enter resonance condition, remained capacity unit is connected with resonance current effective value sampling unit with described resonance current frequency detecting unit respectively, for setting up impedance equation, load is identified, inductance control unit is connected with described remained capacity unit, inductance control unit is also connected with coil control switch Kn respectively, be preset with equivalent load impedance and former limit resonant inductance optimal value one to one in inductance control unit, inductance control unit is according to equivalent load impedance Z _lvalue, the corresponding relation according to equivalent load impedance and former limit resonant inductance optimal value obtains the optimal value of former limit resonant inductance, and the conducting of control coil control switch Kn and cut-out, realizes the optimal value adjustment of former limit resonant inductance.

In another kind of preferred implementation of the present invention, former limit circuit can also be provided with current transformer, current transformer is for obtaining the current waveform of former limit circuit resonance state, and the output of current transformer is connected with the input of resonance current over-zero sampling unit with resonance current frequency detecting unit, resonance current effective value value sampling unit.Realize the detection of former limit circuital current safely and reliably.

In the present embodiment, former limit resonant inductance Lp, the former limit building-out capacitor Cp of the series connection of former limit are equivalent to a filter, present larger impedance to high-frequency harmonic voltage, reduce the high-frequency harmonic electric current that inverter exports square-wave voltage.The fundamental signal being in resonance frequency can by Energy Transfer to secondary loop.In the present embodiment, system works is under Sofe Switch pattern, and voltage source inverter circuit exports the effective value u of square-wave voltage _pcan be approximately:

$u_P=\frac{{4E}_{\mathrm{DC}}}{\sqrt{2}\mathrm{\π}}---\left(5\right)$

Present invention also offers a kind of IPT system former limit power regulating method based on controlled inductance, as shown in Figure 4, comprise the steps:

S1: set up voltage-type IPT system;

S2: controller cuts off capacitance selection switch S, and make the first electric capacity C1 access former limit circuit, DC power supply carries out direct current supply to former limit circuit, makes described former limit circuit enter resonance condition;

S3: current sensing means detects the electric current of former limit circuit and by described current delivery to described controller, described controller obtains the first effective value and first operating frequency of described former limit circuital current;

S4: controller closes electric capacity selector switch S, access former limit circuit after making the first electric capacity C1 and the second electric capacity C2 parallel connection, DC power supply carries out direct current supply to former limit circuit, and controller regulates the operating frequency of inverter to make former limit circuit enter resonance condition;

S5: current sensing means detects the electric current of former limit circuit and by described current delivery to described controller, described controller obtains the second effective value and second operating frequency of described former limit circuital current;

S6: controller sets up impedance equation according to the first effective value of described former limit circuital current, the second effective value and corresponding operating frequency, asks for equivalent load impedance Z _l;

S7: controller cuts off capacitance selection switch S, and make the first electric capacity C1 access former limit circuit, described controller is according to equivalent load impedance Z _lvalue, the corresponding relation according to equivalent load impedance and former limit resonant inductance optimal value obtains the optimal value of former limit resonant inductance, and the conducting of control coil control switch Kn and cut-out, realizes the optimal value of former limit resonant inductance.

In the present invention, coupling circuit is operated in former edge point resonance condition, its Central Plains edge divides resonance to refer to current system operating frequency, loop, former and deputy limit separately reactance is all not equal to zero, and secondary loop equals zero to the reflected reactance in loop, former limit and primary return from reactance sum.Changed the former edge point resonance frequency of circuit by the mode switching energy transmitting terminal building-out capacitor, in the present embodiment, controllable switch S is formed by two IGBT differential concatenations, and the control signal receiving controller triggers it and opens shutoff.The gate-controlled switch be made up of IGBT not only easily controls, and can make that the pressure drop of circuit in switch S is little, power loss is little.

In the present invention, before regulating former limit resonant inductance, first detect the size of equivalent load impedance, concrete grammar is:

As controller roof-cut resistence S, the first electric capacity C1 connecting system, system works is in complex resonance state, and system operating frequency is secondary natural frequency w0, meets relational expression:

$\frac{1}{{\mathrm{\ω}}_0^2}=L_P{C}_1=L_S{C}_S---\left(6\right)$

When there being load input coefficient, controller Closing Switch S, first electric capacity C1 and the second electric capacity C2 is incorporated to system, system former limit off resonance, controller regulates inverter operating frequency to make system works when former limit partial resonance by detecting current zero-crossing point, and because the former limit of circuit during stable state always works in resonance condition, inversion exports square-wave voltage and loop current in the same way, current waveform is sinusoidal wave, therefore all can participate in calculating with effective value.

In ICPT system, Zr is that the pickup of secondary energy holds equiva lent impedance Zs at the reflected umpedance of former edge emitting end, can reflect the impact of secondary loop on loop, former limit, can be calculated by formula (7) (8)

Z _S＝jωL _S+1jωC _S+jImZ _L+ReZ _L+R _S（7）

Z _r＝ω ²M ²Z _S＝ReZ _r+jImZ _r（8）

The real part imaginary part calculating reflected umpedance is respectively:

$\mathrm{Re}{Z}_r=\frac{{\mathrm{\ω}}^2{M}^2(R_S+\mathrm{Re}{Z}_L)}{{(R_S+\mathrm{Re}{Z}_L)}^2+(1/\mathrm{\ω}{C}_s-\mathrm{\ω}{L}_S-\mathrm{Im}{Z}_L)}---\left(9\right)$

$\mathrm{Im}{Z}_r=\frac{{\mathrm{\ω}}^2{M}^2(1/\mathrm{\ω}{C}_S-\mathrm{\ω}{L}_S-\mathrm{Im}{Z}_L)}{{(R_S+\mathrm{Re}{Z}_L)}^2+(1/\mathrm{\ω}{C}_s-\mathrm{\ω}{L}_S-\mathrm{Im}{Z}_L)}---\left(10\right)$

The energy that the real part of reflected umpedance consumes is from the elementary energy being sent to secondary loop, and imaginary part is used for quadergy and exchanges, and participates in former limit loop resonance.

Former limit energy transmitting terminal total impedance Zp is:

Z _P＝jωL _P+1jωC _P+jImZ _r+ReZ _r+R _P（11）

When electric capacity C1 cuts circuit, during systematic steady state, former limit resonance frequency is w1, and now systematic reflection impedance is:

$Z_{r1}={\mathrm{\ω}}_1^2{M}^2/Z_S---\left(12\right)$

Former limit energy transmitting terminal loop current Ip1 is:

$I_{P1}=\frac{u_P}{\mathrm{Re}{Z}_{r1}+R_P}---\left(13\right)$

If load is purely resistive load, now system works is in former secondary complex resonance state, and system operating frequency is system frequency.If resistance inductive load, it is comparatively far away that now primary return partial resonance frequency can depart from natural resonance frequency, clearly can be distinguished the character of load by the degree of the system primary loop works frequency departure natural resonance frequency when the first electric capacity C1 is building-out capacitor.

Switch S conducting afterwards, the second electric capacity C2 is incorporated to circuit, and controller makes system former limit partial resonance by regulating the output voltage frequency of inverter automatically to regulate, and during systematic steady state, former limit resonance frequency is w ₂, now systematic reflection impedance is:

$Z_{r2}={\mathrm{\ω}}_2^2{M}^2/Z_S---\left(14\right)$

Former limit energy transmitting terminal loop current IP2 is:

$I_{P2}=\frac{u_P}{\mathrm{Re}{Z}_{r2}+R_P}---\left(15\right)$

When resonance complete in Sofe Switch guarantee system former limit energy transmitting terminal, energy transmitting terminal loop imaginary part is zero, that is:

ImZ _r1+ω ₁L _P-1ω ₁C ₁＝0 （16）

$\mathrm{Im}{Z}_{r2}+{\mathrm{\ω}}_2{L}_P-\frac{1}{{\mathrm{\ω}}_2(C_1+C_2)}=0---\left(17\right)$

The more than simultaneous various numerical value obtaining load:

$\mathrm{Im}{Z}_L=\frac{\mathrm{Im}{\mathrm{Zr}}_1\×(u_P-I_{P2}{R}_P)\×I_{P1}\×({\mathrm{\ω}}_2{L}_S-1/{\mathrm{\ω}}_2{C}_S)-\mathrm{Im}{\mathrm{Zr}}_2\×(u_P-I_{P1}{R}_P)\×I_{P2}\×({\mathrm{\ω}}_1{L}_S-1/{\mathrm{\ω}}_1{C}_S)}{\mathrm{Im}{\mathrm{Zr}}_2\×(u_P-I_{P1}{R}_P)\×I_{P2}-\mathrm{Im}{\mathrm{Zr}}_1\×(u_P-I_{P2}{R}_P)\×I_{P1}}$

（18）

$\mathrm{Re}{Z}_L=\frac{(u_P-I_{P2}{R}_P)\×(1/{\mathrm{\ω}}_2{C}_S-{\mathrm{\ω}}_2{L}_S-\mathrm{Im}{Z}_L)}{\mathrm{Im}{\mathrm{Zr}}_2\×I_{P2}}---\left(19\right)$

Wherein, Rp is primary coil internal resistance and electric capacity internal resistance, and Rs is secondary coil internal resistance, u _pfor the voltage that inverter bridge exports, I _p1for with former limit circuit first effective value, I _p2for former limit circuit second effective value, w ₁for only have first electric capacity C1 cut circuit time former limit resonance frequency, i.e. the first operating frequency, w ₂be the resonance frequency on the first electric capacity C1 and the second electric capacity C2 former limit when all cutting circuit, i.e. the second operating frequency.The present invention, by setting up impedance equation, accurately can identify load.

In the present embodiment, in the controller also there is mutual inductance identification module, this mutual inductance identification module is connected with resonance current effective value sampling unit with remained capacity unit, resonance current frequency detecting unit respectively, and for identifying the size of mutual inductance, specific formula for calculation is:

$M=\sqrt{\frac{\mathrm{Im}{\mathrm{Zr}}_2\×[\mathrm{Re}{Z_S}^2+(1/{\mathrm{\ω}}_2{C}_S-{\mathrm{\ω}}_2{L}_S-\mathrm{Im}{Z}_L)]}{{\mathrm{\ω}}_2^2\×(1/{\mathrm{\ω}}_2{C}_S-{\mathrm{\ω}}_2{L}_S-\mathrm{Im}{Z}_L)}}---\left(20\right)$

In the present embodiment, in order to reduce the system problem that in primary return off resonance process, the loss of inverter switching device pipe increases when electric capacity switches, can before switch-capacitor, by controller, inverter switching device pipe S2, S3 are turned off, S1, S4 conducting, until the complete switching carrying out electric capacity afterwards of energy dissipation in the resonant circuit of former limit, controller makes switching tube conducting and makes inverter recover normal operating conditions afterwards.

In one preferred embodiment of the invention, against actual load values in the detected value of load detecting value and mutual inductance and circuit is compared analysis.Shown in design parameter table 1 in circuit.

Table 1. system default parameter

Parameter name	Parameter value	Parameter name	Parameter value
				Input voltage Edc	100V	Building-out capacitor Cs	21.1nF
Building-out capacitor C1	14.785nF	Resonant inductance Ls	481uH
				Building-out capacitor C2	1.215nF	Launching circuit line resistance Rs	0.5Ω
Resonant inductance Lp	685.31uH	Pickup loops line resistance Rp	0.3Ω

The system parameters recognition result under resistive load and resistance sense loading condition is respectively shown in table 2 and table 3.

Parameter identification result during table 2. resistive load

The parameter identification result during load of table 3. resistance sense

From table 2 and table 3, the present invention can this identification load and mutual inductance parameter.When resistive load, accuracy of identification is higher, is 1.6% to the maximum to the identification error of mutual inductance M, is 1% to the maximum to the identification error of resistive load; Be 1.9% to the maximum identification error of mutual inductance, be 4.8% to the real part identification worst error of resistance sense load, 3.8% is to the maximum to the identification error of induction reactance.

In the present embodiment, when the load imaginary part recognized is less than 1 μ H, illustrates that this to fluctuate the error brought due to former limit overall resonance frequency value and current effective value, think that load is purely resistive.When the load inductive part recognized is greater than 1uH, illustrate that actual loading is resistance sense load.

The present invention, by changing the size of former limit building-out capacitor, under making former limit be operated in two kinds of different resonance frequencys, by setting up mode reflected umpedance equation, realizing load and accurately identifying.

After detecting load, controller cuts off capacitance selection switch S, and make the first electric capacity C1 access former limit circuit, controller is according to equivalent load impedance Z _lvalue, the corresponding relation according to equivalent load impedance and former limit resonant inductance optimal value obtains the optimal value of former limit resonant inductance, and the conducting of control coil control switch Kn and cut-out, realizes the adjustment of former limit resonant inductance.Specifically when controlling, when former limit power stage efficiency meets design requirement, if the optimal value of former limit resonant inductance is a numerical point, when the inductance value of the inductance coil of integer circle equals former limit resonant inductance optimal value, control coil control switch Kn conducting makes former limit resonant inductance be taken as the inductance value equaling former limit resonant inductance optimal value, when the inductance value of the inductance coil of integer circle is not equal to former limit resonant inductance optimal value, former limit resonant inductance is taken as the inductance value that be greater than former limit resonant inductance optimal value minimum with former limit resonant inductance optimal value difference, such as, the inductance of former limit single-turn circular coil is 0.1uH, when requiring that former limit delivery efficiency is not less than 80%, if the optimal value of the former limit resonant inductance that equivalent load impedance is corresponding is 0.9uH, former limit resonant inductance is taken as the inductance value equaling former limit resonant inductance optimal value, i.e. 0.9uH, then controller makes control coil control switch K1, K2, K9 conducting, coil 1 to coil 9 place in circuit, if the optimal value of the former limit resonant inductance that equivalent load impedance is corresponding is 0.95uH, former limit resonant inductance is taken as the inductance value that be greater than former limit resonant inductance optimal value minimum with former limit resonant inductance optimal value difference, i.e. 1uH, controller make control coil control switch K1, K2 ..., K9, K10 conducting, coil 1 to coil 10 place in circuit.

In the present embodiment, if the optimal value of former limit resonant inductance is a number range, the inductance value of then getting minimum integer circle inductance coil corresponding within the scope of it is former limit resonant inductance value, such as the inductance of former limit single-turn circular coil is 0.1uH, when former limit power stage efficiency meets design requirement, the optimal value of former limit resonant inductance is 0.9uH-1.5uH, the inductance value of the inductance coil of smallest positive integral circle corresponding within the scope of it is 0.9uH, controller make control coil control switch K1, K2 ..., K9 conducting, coil 1 to coil 9 place in circuit.

In the present embodiment, former limit power stage efficiency can require to determine according to specific design, in a preferred embodiment of the invention, requires that former limit delivery efficiency is not less than 80%.

In the present embodiment, control coil is number consecutively from outside to inside, and namely coil 1 is positioned at outermost.

It should be noted that, although the present invention is described for SS type IPT system, for SP type IPT system, the present invention is applicable equally, and this is also within protection scope of the present invention.

In the description of this specification, specific features, structure, material or feature that the description of reference term " embodiment ", " some embodiments ", " example ", " concrete example " or " some examples " etc. means to describe in conjunction with this embodiment or example are contained at least one embodiment of the present invention or example.In this manual, identical embodiment or example are not necessarily referred to the schematic representation of above-mentioned term.And the specific features of description, structure, material or feature can combine in an appropriate manner in any one or more embodiment or example.

Although illustrate and describe embodiments of the invention, those having ordinary skill in the art will appreciate that: can carry out multiple change, amendment, replacement and modification to these embodiments when not departing from principle of the present invention and aim, scope of the present invention is by claim and equivalents thereof.

Claims (5)

1. carry out a system for power adjustments based on the former limit of IPT system of controlled inductance, it is characterized in that: comprise voltage-type IPT system and controller;

Described voltage-type IPT system is made up of former limit circuit and secondary circuit;

Described former limit circuit is provided with full-bridge inverter, the power end of described full-bridge inverter connects DC power supply, output and former limit resonant inductance Lp, former limit building-out capacitor Cp are connected to form a series loop, described former limit building-out capacitor Cp comprises the first electric capacity C1 in parallel and the second electric capacity C2, described second electric capacity C2 is connected by capacitance selection switch S control realization and cuts off, described capacitance selection switch S is connected with controller, by the break-make of controller control capacitance selector switch S;

Equivalent load impedance and former limit resonant inductance optimal value is one to one preset with in described controller;

Described former limit resonant inductance Lp comprises N circle coil, and the n-th circle coils connected in series has a coil control switch Kn, and described coil control switch Kn is connected with described controller, and by controller control realization break-make, wherein, N is positive integer, n=1,2 ..., N-1, N;

Described former limit circuit is also provided with current sensing means, described current sensing means is connected with described former limit resonant inductance Lp, described current sensing means is also connected with described controller, and described current sensing means is for detecting electric current in described former limit resonant inductance Lp and by described current delivery to described controller;

Described secondary circuit comprises at least one secondary electronic circuit, and each secondary electronic circuit is by secondary resonant inductance Ls, secondary building-out capacitor Cs, load impedance Z _lmcomposition, described secondary resonant inductance Ls, secondary building-out capacitor Cs and load impedance Z _lmthree is connected to form a series loop successively, and at synchronization, only have the work of a secondary electronic circuit, m is positive integer;

Described current sensing means comprises resonance current frequency detecting unit, resonance current effective value sampling unit and resonance current over-zero sampling unit, described resonance current frequency detecting unit is for detecting the resonance frequency of primary current, and described resonance current effective value sampling unit and resonance current over-zero sampling unit carry out effective value sampling and current over-zero sampling to the current waveform of former limit circuit respectively;

The input of described controller is connected with the output of described current sensing means, described controller comprises frequency adjustment unit, remained capacity unit and inductance control unit, the output of described resonance current zero passage sampling unit is connected with the input of described frequency adjustment unit, the output of described frequency adjustment unit is connected with full-bridge inverter, the electric voltage frequency that described frequency adjustment unit regulates full-bridge inverter to export according to the current zero-crossing signal of described resonance current zero passage sampling unit collection makes former limit circuit enter resonance condition, described remained capacity unit is connected with resonance current effective value sampling unit with described resonance current frequency detecting unit respectively, for setting up impedance equation, load is identified, described inductance control unit is connected with described remained capacity unit, described inductance control unit is also connected with coil control switch Kn respectively, be preset with equivalent load impedance and former limit resonant inductance optimal value one to one in described inductance control unit, described inductance control unit is according to equivalent load impedance Z _lvalue, the corresponding relation according to described equivalent load impedance and former limit resonant inductance optimal value obtains the optimal value of former limit resonant inductance, and the conducting of control coil control switch Kn and cut-out, and the optimal value realizing former limit resonant inductance regulates.

2. the system of power adjustments is carried out on the former limit of IPT system based on controlled inductance as claimed in claim 1, it is characterized in that: described former limit circuit is also provided with current transformer, described current transformer is for obtaining the current waveform of former limit circuit resonance state, and the output of described current transformer is connected with the input of resonance current over-zero sampling unit with described resonance current frequency detecting unit, described resonance current effective value value sampling unit.

3. the system of carrying out power adjustments based on the former limit of IPT system based on controlled inductance described in claim 1 carries out a power regulating method, it is characterized in that: comprise the steps:

S1: set up voltage-type IPT system, described voltage-type IPT system is made up of former limit circuit and secondary circuit; Described former limit circuit is provided with full-bridge inverter, the power end of described full-bridge inverter connects DC power supply, output and former limit resonant inductance Lp, former limit building-out capacitor Cp are connected to form a series loop, described former limit building-out capacitor Cp comprises the first electric capacity C1 in parallel and the second electric capacity C2, described second electric capacity C2 is connected by capacitance selection switch S control realization and cuts off, described capacitance selection switch S is connected with controller, by the break-make of controller control capacitance selector switch S;

Equivalent load impedance and former limit resonant inductance optimal value is one to one preset with in described controller, described former limit resonant inductance optimal value be former limit building-out capacitor Cp be the first electric capacity C1, former limit power stage efficiency meet design requirement time, corresponding to the inductance value of described equivalent load impedance;

Described former limit resonant inductance Lp comprises N circle coil, and the n-th circle coils connected in series has a coil control switch Kn, and described coil control switch Kn is connected with described controller, by controller control realization break-make, wherein, described N is positive integer, described n=1,2 ..., N-1, N;

Described former limit circuit is also provided with current sensing means, described current sensing means is connected with described former limit resonant inductance Lp, described current sensing means is also connected with described controller, and described current sensing means is for detecting electric current in described former limit resonant inductance Lp and by described current delivery to described controller;

Described secondary circuit comprises at least one secondary electronic circuit, and each secondary electronic circuit is by secondary resonant inductance Ls, secondary building-out capacitor Cs, load impedance Z _lmcomposition, described secondary resonant inductance Ls, secondary building-out capacitor Cs and load impedance Z _lmthree is connected to form a series loop successively, and at synchronization, only have the work of a secondary electronic circuit, described m is positive integer;

S2: controller cuts off capacitance selection switch S, and make the first electric capacity C1 access former limit circuit, DC power supply carries out direct current supply to former limit circuit, makes described former limit circuit enter resonance condition;

S3: current sensing means detects the electric current of former limit circuit and by described current delivery to described controller, described controller obtains the first effective value and first operating frequency of described former limit circuital current;

S4: controller closes electric capacity selector switch S, access former limit circuit after making the first electric capacity C1 and the second electric capacity C2 parallel connection, DC power supply carries out direct current supply to former limit circuit, and controller regulates the operating frequency of inverter to make former limit circuit enter resonance condition;

S5: current sensing means detects the electric current of former limit circuit and by described current delivery to described controller, described controller obtains the second effective value and second operating frequency of described former limit circuital current;

S6: controller sets up impedance equation according to the first effective value of described former limit circuital current, the second effective value and corresponding operating frequency, asks for equivalent load impedance Z _l;

S7: controller cuts off capacitance selection switch S, and make the first electric capacity C1 access former limit circuit, described controller is according to equivalent load impedance Z _lvalue, the corresponding relation according to equivalent load impedance and former limit resonant inductance optimal value obtains the optimal value of former limit resonant inductance, and the conducting of control coil control switch Kn and cut-out, realizes the adjustment of former limit resonant inductance.

4. power regulating method as claimed in claim 3, it is characterized in that: the input of described current sensing means is connected with former limit circuit, described current sensing means comprises resonance current frequency detecting unit, resonance current effective value sampling unit and resonance current over-zero sampling unit, described resonance current frequency detecting unit is for detecting the resonance frequency of primary current, and described resonance current effective value sampling unit and resonance current over-zero sampling unit carry out effective value sampling and current over-zero sampling to the current waveform of former limit circuit respectively;

The input of described controller is connected with the output of described current sensing means, described controller comprises frequency adjustment unit, remained capacity unit and inductance control unit, the output of described resonance current zero passage sampling unit is connected with the input of described frequency adjustment unit, the output of described frequency adjustment unit is connected with full-bridge inverter, the electric voltage frequency that described frequency adjustment unit regulates full-bridge inverter to export according to the current zero-crossing signal of described resonance current zero passage sampling unit collection makes former limit circuit enter resonance condition, described remained capacity unit is connected with resonance current effective value sampling unit with described resonance current frequency detecting unit respectively, for setting up impedance equation, load is identified, described inductance control unit is connected with described remained capacity unit, described inductance control unit is also connected with coil control switch Kn respectively, equivalent load impedance and former limit resonant inductance optimal value is one to one preset with in described inductance control unit, described inductance control unit is according to the value of equivalent load impedance ZL, corresponding relation according to described equivalent load impedance and former limit resonant inductance optimal value obtains the optimal value of former limit resonant inductance, and the conducting of control coil control switch Kn and cut-out, the optimal value realizing former limit resonant inductance regulates.

5. power regulating method as claimed in claim 3, is characterized in that: the described impedance equation set up according to the first effective value, the second effective value and corresponding operating frequency is:

Im Z _r1+ω ₁L _P-1/ω ₁C ₁＝0

Wherein, Rp is primary coil internal resistance and electric capacity internal resistance, and Rs is secondary coil internal resistance, u _pfor the voltage that inverter bridge exports, I _p1for with former limit circuit first effective value, I _p2for former limit circuit second effective value, w ₁for only have first electric capacity C1 cut circuit time former limit resonance frequency, w ₂it is the resonance frequency on the first electric capacity C1 and the second electric capacity C2 former limit when all cutting circuit.