CN103490527A - Load identifying method and system of voltage type wireless power supply system - Google Patents

Abstract

The invention provides a load identifying method and a system of a voltage type wireless power supply system. The load identifying method comprises the following steps: building a voltage type IPT (Intelligent Peripheral Interface) system, wherein a primary compensation capacitor Cp of the voltage type IPT system comprises a first capacitor and a second capacitor which are connected in parallel, and the second capacitor is controlled by a controller to realize switch-on or switch-off through a switch; connecting the first capacitor into a primary circuit to allow the primary circuit to enter a resonance state; detecting the current of the primary circuit by a current detecting device to obtain a first effective value; closing the switch to connect the first capacitor and the second capacitor which are connected in parallel into the primary circuit, and adjusting the work frequency of an inverter through a controller to allow the primary circuit to enter a resonance state; detecting the current of the primary circuit by the current detecting device to obtain a second effective value; and building an impedance equation by a controller according to the first effective value and the second effective value of the currents of the primary circuit as well as corresponding work frequencies, thereby obtaining an equivalent load impedance (ZL). The method and the system can be used for correctly detecting the load, so that the IPT system enters an optimal power transfer stage.

Description

A kind of voltage-type wireless power supply system load recognition methods and system

Technical field

The present invention relates to IPT(Inductive Power Transfer, induction electric energy transmission) the load recognition technology of system, be specifically related to a kind of voltage-type wireless power supply system load recognition methods and system.

Background technology

The IPT technology is based on the Faradic electricity magnetic induction principle, utilizes high-frequency alternating magnetic field to realize the power supply technique of electric energy a kind of new type of safe of wireless transmission between the power-supply system of complete electrical insulation and removable load.This technology is widely used in fields such as electric automobile, rotation power consumption equipment, biologic medical, household electrical appliances and mobile electronic devices.Due to the load-carrying power nature of IPT system institute and grade span large (several milliwatts to upper kilowatt), if character and the watt level of load are not carried out to identification, the stability of IPT system works and reliability can reduce greatly.Therefore, before the normal operation of IPT system, character and the power capacity of reply load are identified, thereby enter the corresponding power delivery stage that is suitable for this load.

Because the IPT system has following characteristics usually, the one, comprise more energy-storage travelling wave tube, its exponent number is generally higher than 3; The 2nd, owing to comprising the nonlinear switching network in system, therefore present serious switch non-linear; The 3rd,, due to the operating frequency of IPT system, generally in the 20-100kHz left and right, so its operating frequency is higher.For the IPT system of high-order, non-linear and high frequency, carry out load parameter identification difficult, at present, traditional recognition technology is mainly utilized the identification that differs to carry out load between former limit resonance potential and electric current, need to detect too many variable, make control system very complicated, more difficult realization.

For voltage-type IPT system, if adopt the mode of wireless communication module to realize load torque identification, due to the high frequency magnetic field that has power delivery and radio communication simultaneously, the interference that both are mutual, likely can make the reliability of Energy Transfer and radio communication reduce.If adopt the discrimination method based on reflected umpedance and detection resonance potential and current and phase difference, although accurate identification load in theory, but in fact, owing to will detecting current peak, voltage peak and both differ, cause hardware circuit and complexity thereof, too much tested measurement easily affects the accuracy of actual loading identification.

Summary of the invention

In order to overcome the defect existed in above-mentioned prior art, the purpose of this invention is to provide a kind of voltage-type wireless power supply system load recognition methods and system, can accurately identify the load of IPT system.

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 voltage-type wireless power supply system load recognition methods, comprise the steps:

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

Described former limit circuit is provided with the former limit resonant tank of DC power supply, full-bridge inverter and former limit resonant inductance Lp and former limit building-out capacitor Cp composition, described former limit building-out capacitor Cp comprises the first capacitor C 1 and the second capacitor C 2 in parallel, described the second capacitor C 2 is controlled and is realized connecting and cutting off by switch S, and described switch S is connected with controller;

Described secondary circuit comprises secondary resonant inductance Ls, secondary building-out capacitor Cs and equivalent load impedance Z _l, described secondary resonant inductance Ls, secondary building-out capacitor Cs and equivalent load impedance Z _lthe three is connected to form the secondary resonant tank successively;

Described former limit circuit also is provided with current sensing means, and this current sensing means is for detection of the electric current in described former limit resonant inductance Lp;

S2: controller cuts off switch S, only allows the first capacitor C 1 access former limit circuit, and DC power supply is carried 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 the first effective value of former limit circuital current and the first operating frequency is sent in described controller;

S4: controller Closing Switch S, make the first capacitor C 1 and the second capacitor C 2 former limit of rear access in parallel circuit, DC power supply is carried out direct current supply to former limit circuit, and the operating frequency that controller is regulated inverter makes former limit circuit enter resonance condition;

S5: current sensing means detects the electric current of former limit circuit and the second effective value of former limit circuital current and the second operating frequency is transferred in described controller;

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

The present invention, by changing the size of former limit building-out capacitor, is operated under two kinds of different resonance frequencys former limit, by setting up mode reflected umpedance equation, realizes that load accurately identifies, and makes the IPT system in the best power transmit stage.

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 voltage-type wireless power supply system load recognition system, comprise voltage-type IPT system, current sensing means and controller;

Described voltage-type IPT system is comprised of former limit circuit and secondary circuit, described former limit circuit is provided with the former limit resonant tank of DC power supply, full-bridge inverter and former limit resonant inductance Lp and former limit building-out capacitor Cp composition, described former limit building-out capacitor Cp comprises the first capacitor C 1 and the second capacitor C 2 in parallel, described the second capacitor C 2 is controlled and is realized connecting and cutting off by switch S, and described switch S is connected with controller;

Described secondary circuit comprises secondary resonant inductance Ls, secondary building-out capacitor Cs and equivalent load impedance Z _l, described secondary resonant inductance Ls, secondary building-out capacitor Cs and equivalent load impedance Z _lthe three is connected to form the secondary resonant tank successively;

Described current sensing means is for detection of the first effective value, the first operating frequency, the second effective value and second operating frequency of former limit circuital current, controller is set up impedance equation according to the first effective value, the first operating frequency, the second effective value and second operating frequency of former limit circuital current, asks for equivalent load impedance Z _l.

Voltage-type wireless power supply system load recognition system of the present invention can realize the accurate detection of load, makes the IPT system enter the best power transmit stage.

In a kind of preferred implementation of the present invention, the impedance equation that controller is set up according to the first effective value, the first operating frequency, the second effective value and the second operating frequency is:

$\mathrm{Im}{Z}_L=\frac{\mathrm{Im}{\mathrm{Zr}}_1\&CenterDot;(u_P-I_{P2}{R}_P)\&CenterDot;I_{P1}\&CenterDot;({\mathrm{\&omega;}}_2{L}_S-1/{\mathrm{\&omega;}}_2{C}_S)-\mathrm{Im}{\mathrm{<figure-callout\; id="2"\; label="Zr"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Zr</figure-callout>}}_2\&CenterDot;(u_P-I_{P1}{R}_P)\&CenterDot;I_{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">P</figure-callout>}2}\&CenterDot;({\mathrm{\&omega;}}_1{L}_S-1/{\mathrm{\&omega;}}_1{C}_S)}{\mathrm{Im}{\mathrm{Zr}}_2\&CenterDot;(u_P-I_{P1}{R}_P)\&CenterDot;I_{P2}-\mathrm{Im}{\mathrm{Zr}}_1\&CenterDot;(u_P-I_{P2}{R}_P)\&CenterDot;I_{P1}}$

$\mathrm{Re}{Z}_L=\frac{(u_P-I_{P2}{R}_P)\&CenterDot;(1/{\mathrm{\&omega;}}_2{C}_S-{\mathrm{\&omega;}}_2{L}_S-\mathrm{Im}{Z}_L)}{\mathrm{Im}{\mathrm{<figure-callout\; id="2"\; label="Zr"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Zr</figure-callout>}}_2\&CenterDot;I_{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">P</figure-callout>}2}}$

ImZ _r1+ω ₁L _P-1/ω ₁C ₁＝0

$\mathrm{Im}{\mathrm{<figure-callout\; id="2"\; label="Z\; r"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Z</figure-callout>}}_r+{\mathrm{\&omega;}}_2{L}_P-\frac{1}{{\mathrm{\&omega;}}_2(C_1+C_2)}=0$

Wherein, Rp is primary coil internal resistance and electric capacity internal resistance sum, and Rs is the secondary coil internal resistance, u _pfor the voltage of inverter bridge output, I _p1for the first effective value with primary current, I _p2for the second effective value of primary current, ω ₁be the first operating frequency, ω ₂it is the second operating frequency.The present invention, by setting up impedance equation, can accurately identify load.

In another kind of preferred implementation of the present invention, described current sensing means is provided with current transformer, this current transformer is for obtaining the current waveform of former limit circuit resonance state, at the output of current transformer, is connected with respectively resonance current frequency detecting unit, resonance current effective value value sampling unit and resonance current zero passage sampling unit.

Described controller comprises frequency adjustment unit and load recognition unit, the frequency that the voltage of full-bridge inverter output is regulated according to the current zero-crossing signal of described resonance current zero passage sampling unit collection in described frequency adjustment unit makes former limit circuit enter resonance condition, described load recognition unit is connected with described resonance current effective value sampling unit with described resonance current frequency detecting unit respectively, for setting up impedance equation, load is identified and exported.

Remarkable result of the present invention is: method step is simple, circuit structure is easily realized, only need to detect effective value and the operating frequency of primary current in different resonant capacitance access situations in implementation process, can go out the access situation of load by automatic decision, accuracy of detection is high, error is little, effectively realizes the load identification of radio energy transmission system.

The accompanying drawing explanation

Above-mentioned and/or additional aspect of the present invention and advantage are from obviously and easily understanding becoming the description of embodiment in conjunction with following accompanying drawing, wherein:

Fig. 1 is SS voltage-type IPT circuit system schematic diagram in a kind of preferred real-time mode of the present invention;

Fig. 2 is the structure chart of current sensing means and controller in a kind of preferred implementation of the present invention;

Fig. 3 is the flow chart of voltage-type wireless power supply system load recognition methods of the present invention.

Embodiment

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

In description of the invention, unless otherwise prescribed and limit, it should be noted that, term " installation ", " being connected ", " connection " should be done broad understanding, for example, can be mechanical connection or electrical connection, can be also the connection of two element internals, can be directly to be connected, and also can indirectly be connected by intermediary, for the ordinary skill in the art, can understand as the case may be the concrete meaning of above-mentioned term.

The invention provides a kind of voltage-type wireless power supply system load recognition system, as shown in Figure 1, it comprises voltage-type IPT system and controller, and wherein, voltage-type IPT system is comprised 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 resonant tank, as can be seen from Fig. 1, former limit building-out capacitor Cp comprises the first capacitor C 1 and the second capacitor C 2 in parallel, the second capacitor C 2 is controlled and is realized connecting and cutting off by switch S, switch S is connected with controller, by the break-make of controller control switch S.Former limit circuit also is provided with current sensing means, current sensing means is connected with former limit resonant inductance Lp, current sensing means also is connected with controller, and current sensing means is for detection of the electric current in former limit resonant inductance Lp and generate effective value information and the resonance frequency information of this electric current.Secondary circuit is by secondary resonant inductance Ls, secondary building-out capacitor Cs, equivalent load impedance Z _lform secondary resonant inductance Ls, secondary building-out capacitor Cs and equivalent load impedance Z _lthe three is connected to form a series resonant tank successively.

As shown in Figure 1, switch S 1-S4 forms a full-bridge inverter worked under soft switching mode, direct current input E _dCby changing high-frequency alternating current u after inverter into _pand produce high-frequency alternating magnetic field, secondary resonant inductance Ls interrogation energy from high-frequency alternating magnetic field, u in figure by energy transmitting terminal resonant network _pfor the square-wave voltage of exporting after inversion, i _pand i _sbe respectively former limit, secondary loop current, M is the mutual inductance between coil, and Rp is primary coil internal resistance and electric capacity internal resistance, and Rs is the secondary coil internal resistance.

As shown in Figure 2, 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, the resonance current frequency detecting unit is for detection of 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 electric current of former limit circuit respectively.The input of controller is connected with the output of current sensing means, controller comprises frequency adjustment unit and load recognition unit, the output of resonance current zero passage sampling unit is connected with the input of frequency adjustment unit, the output of frequency adjustment unit and four switches of full-bridge inverter be connected respectively (in Fig. 1, not illustrating), the frequency that the voltage of full-bridge inverter output is regulated according to the current zero-crossing signal of resonance current zero passage sampling unit collection in the frequency adjustment unit makes former limit circuit enter resonance condition, specifically make voltage and the primary current same-phase of the full-bridge inverter output of former limit, the load recognition unit is connected with resonance current effective value sampling unit with the resonance current frequency detecting unit respectively, for setting up impedance equation, load is identified and exported.

In another kind of preferred implementation of the present invention, on the circuit of former limit, current transformer can also be installed, 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 safely and reliably the detection of former limit circuital current.

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, and high-frequency harmonic voltage is presented to larger impedance, have reduced the high-frequency harmonic electric current of inverter output square-wave voltage.Fundamental signal in resonance frequency can be by Energy Transfer to secondary loop.In the present embodiment, system works is under soft switching mode, and the voltage source inverter circuit is exported the effective value u of square-wave voltage _pcan be approximately:

$u_P=\frac{{4\mathrm{<figure-callout\; id="2"\; label="E\; DC"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">E</figure-callout>}}_{\mathrm{DC}}}{\sqrt{2}\mathrm{\&pi;}}---\left(1\right)$

The present invention also provides a kind of voltage-type wireless power supply system load recognition methods, as shown in Figure 3, comprises the steps:

S1: set up voltage-type IPT system;

S2: controller cuts off switch S, only allows the first capacitor C 1 access former limit circuit, and DC power supply is carried 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 the first effective value of former limit circuital current and the first operating frequency is sent in described controller;

S4: controller Closing Switch S, make the first capacitor C 1 and the second capacitor C 2 former limit of rear access in parallel circuit, DC power supply is carried out direct current supply to former limit circuit, and the operating frequency that controller is regulated inverter makes former limit circuit enter resonance condition;

S5: current sensing means detects the electric current of former limit circuit and the second effective value of former limit circuital current and the second operating frequency is transferred in described controller;

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

In the present invention, coupling circuit is operated in former limit partial resonance state, its limit, Central Plains partial resonance refers to the current system operating frequency, loop, former and deputy limit reactance separately all is not equal to zero, and the reflected reactance in Xiang Yuanbian loop, secondary loop and primary return equal zero from the reactance sum.Change the former limit partial resonance frequency of circuit by the mode of 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 that receives controller triggers it and opens shutoff.The gate-controlled switch consisted of IGBT is not only easily controlled, and can make that the pressure drop of circuit on switch S is little, power loss is little.

When controller cuts off switch S, the first capacitor C 1 connecting system, system works is at the complex resonance state, and the system works frequency is secondary natural frequency ω ₀, meet relational expression:

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

When the load input coefficient is arranged, controller Closing Switch S, the first capacitor C 1 and the second capacitor C 2 are incorporated to system, system former limit off resonance, controller is by detecting current zero-crossing point and regulating that the inverter operating frequency makes system works in the situation that the partial resonance of former limit, and during due to stable state, the former limit of circuit always works in resonance condition, and inversion output square-wave voltage and loop current are in the same way, current waveform is sinusoidal wave, therefore all available effective value participates in calculating.

In the ICPT system, Zr is that the secondary energy picks up the reflected umpedance of end equiva lent impedance Zs at former limit transmitting terminal, can reflect the impact in Dui Yuanbian loop, secondary loop, can be calculated by formula (3) (4)

Z _S＝jωL _S+1/jωC _S+jImZ _L+ReZ _L+R _S （3）

Z _r＝ω ²M ²/Z _S＝ReZ _r+jImZ _r （4）

The real part imaginary part that calculates reflected umpedance is respectively:

$\mathrm{Re}{Z}_r=\frac{{\mathrm{\&omega;}}^2{M}^2(R_S+\mathrm{Re}{Z}_L)}{{(R_S+\mathrm{Re}{Z}_L)}^2+(1/\mathrm{\&omega;}{C}_s-\mathrm{\&omega;}{L}_S-\mathrm{Im}{Z}_L)}---\left(5\right)$

$\mathrm{Im}{Z}_r=\frac{{\mathrm{\&omega;}}^2{M}^2(1/\mathrm{\&omega;}{C}_S-\mathrm{\&omega;}{L}_S-\mathrm{Im}{Z}_L)}{{(R_S+\mathrm{Re}{Z}_L)}^2+(1-\mathrm{\&omega;}{C}_s-\mathrm{\&omega;}{L}_S-\mathrm{Im}{Z}_L)}---\left(6\right)$

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

Former limit energy transmitting terminal total impedance Zp is:

Z _P＝jωL _P+1/jωC _P+jImZ _r+ReZ _r+R _P （7）

During capacitor C 1 incision circuit, during systematic steady state, former limit resonance frequency is w1, and now systematic reflection impedance is:

$Z_{r1}={\mathrm{\&omega;}}_1^2{\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">M</figure-callout>}}^2/Z_S---\left(8\right)$

Former limit energy transmitting terminal loop current Ip1 is:

$I_{P1}=\frac{u_p}{\mathrm{Re}{Z}_{r1}+R_P}---\left(9\right)$

If load is pure resistive load, now system works is at former secondary complex resonance state, and the system works frequency is system frequency.If resistance sense load, it is far away that now primary return partial resonance frequency can depart from natural resonance frequency, can clearly distinguish the character of load by the degree of system primary loop works frequency departure natural resonance frequency when the first capacitor C 1 is building-out capacitor.

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

${\mathrm{<figure-callout\; id="2"\; label="Z\; r"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Z</figure-callout>}}_r={\mathrm{\&omega;}}_2^2{\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">M</figure-callout>}}^2/Z_S---\left(10\right)$

Former limit energy transmitting terminal loop current IP2 is:

${\mathrm{<figure-callout\; id="2"\; label="I\; P"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">I</figure-callout>}}_P=\frac{u_p}{\mathrm{<figure-callout\; id="2"\; label="Re\; Z\; r"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Re</figure-callout>}{Z}_r{2}_{}+R_P}---\left(11\right)$

When by soft switch, guaranteeing the complete resonance of the former limit of system energy transmitting terminal, energy transmitting terminal loop imaginary part is zero, that is:

ImZ _r1+ω ₁L _P-1/ω ₁C ₁＝0 （ ¹²）

$\mathrm{<figure-callout\; id="2"\; label="Im\; Z\; r"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Im</figure-callout>}{Z}_r{2}_{}+{\mathrm{\&omega;}}_2{L}_P-\frac{1}{{\mathrm{\&omega;}}_2(C_1+C_2)}=0---\left(13\right)$

The above various numerical value that obtains load of simultaneous:

$\mathrm{Im}{Z}_L=\frac{\mathrm{Im}{\mathrm{Zr}}_1\&CenterDot;(u_P-I_{P2}{R}_P)\&CenterDot;I_{P1}\&CenterDot;({\mathrm{\&omega;}}_2{L}_S-1/{\mathrm{\&omega;}}_2{C}_S)-\mathrm{<figure-callout\; id="2"\; label="Im\; Zr"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Im</figure-callout>}{\mathrm{Zr}}_{}{}_2\&CenterDot;(u_P-I_{P1}{R}_P)\&CenterDot;I_{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">P</figure-callout>}2}\&CenterDot;({\mathrm{\&omega;}}_1{L}_S-1/{\mathrm{\&omega;}}_1{C}_S)}{\mathrm{<figure-callout\; id="2"\; label="Im\; Zr"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Im</figure-callout>}{\mathrm{Zr}}_{}{}_2\&CenterDot;(u_P-I_{P1}{R}_P)\&CenterDot;I_{P2}-\mathrm{Im}{\mathrm{Zr}}_1\&CenterDot;(u_P-I_{P2}{R}_P)\&CenterDot;I_{P1}}---\left(14\right)$

$\mathrm{Re}{Z}_L=\frac{(u_P-I_{P2}{R}_P)\&CenterDot;(1/{\mathrm{\&omega;}}_2{C}_S-{\mathrm{\&omega;}}_2{L}_S-\mathrm{Im}{Z}_L)}{\mathrm{<figure-callout\; id="2"\; label="Im\; Zr"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Im</figure-callout>}{\mathrm{Zr}}_{}{}_2\&CenterDot;I_{P2}}---\left(15\right)$

Wherein, Rp is primary coil internal resistance and electric capacity internal resistance sum, and Rs is the secondary coil internal resistance, u _pfor the voltage of inverter bridge output, I _p1for the first effective value with primary current, I _p2for the second effective value of primary current, ω ₁be the first operating frequency, ω ₂it is the second operating frequency.The present invention, by setting up impedance equation, can accurately identify load.

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

$M=\sqrt{\frac{\mathrm{<figure-callout\; id="2"\; label="Im\; Zr"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Im</figure-callout>}{\mathrm{Zr}}_{}{}_2\&CenterDot;[\mathrm{<figure-callout\; id="2"\; label="Re\; Z\; S"\; filenames="HDA0000395826660000011.png"\; state="\{\{state\}\}">Re</figure-callout>}{Z_S}^{}{{}_{}}^2+(1/{\mathrm{\&omega;}}_2{C}_S-{\mathrm{\&omega;}}_2{L}_S-\mathrm{Im}{Z}_L)]}{{\mathrm{\&omega;}}_2^2\&CenterDot;(1/{\mathrm{\&omega;}}_2{C}_S-{\mathrm{\&omega;}}_2{L}_S-\mathrm{Im}{Z}_L)}}---\left(16\right)$

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

In a preferred embodiment of the present invention, actual loading value in the detected value and to and circuit of load detecting value and mutual inductance is compared to 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

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

Parameter identification result during table 2. resistive load

Parameter identification result during the 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, and the identification error of mutual inductance M is to the maximum to 1.6%, and the identification error of resistive load is to the maximum to 1%; To the maximum identification error of mutual inductance, being 1.9%, is 4.8% to the real part identification worst error of resistance sense load, and the identification error of induction reactance is to the maximum to 3.8%.

In the present embodiment, when the load imaginary part recognized is less than 1 μ H, illustrate that this is the error of bringing due to the fluctuation of former limit overall resonance frequency value and current effective value, thinks that load is pure resistive.When the load perception part recognized is greater than 1 μ H, illustrate that actual loading is the resistance sense load.

The present invention, by changing the size of former limit building-out capacitor, is operated under two kinds of different resonance frequencys former limit, by setting up mode reflected umpedance equation, realizes that load accurately identifies.

It should be noted that, although the present invention be take SS type IPT system and described as example, 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, the description of reference term " embodiment ", " some embodiment ", " example ", " concrete example " or " some examples " etc. means to be contained at least one embodiment of the present invention or example in conjunction with specific features, structure, material or the characteristics of this embodiment or example description.In this manual, the schematic statement of above-mentioned term not necessarily referred to identical embodiment or example.And the specific features of description, structure, material or characteristics can be with suitable mode combinations in any one or more embodiment or example.

Although illustrated and described embodiments of the invention, those having ordinary skill in the art will appreciate that: in the situation that do not break away from principle of the present invention and aim can be carried out multiple variation, modification, replacement and modification to these embodiment, scope of the present invention is limited by claim and equivalent thereof.

Claims (5)

1. a voltage-type wireless power supply system load recognition methods, is characterized in that: comprise the steps:

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

Described former limit circuit is provided with the former limit resonant tank of DC power supply, full-bridge inverter and former limit resonant inductance Lp and former limit building-out capacitor Cp composition, described former limit building-out capacitor Cp comprises the first capacitor C 1 and the second capacitor C 2 in parallel, described the second capacitor C 2 is controlled and is realized connecting and cutting off by switch S, and described switch S is connected with controller;

Described secondary circuit comprises secondary resonant inductance Ls, secondary building-out capacitor Cs and equivalent load impedance Z _l, described secondary resonant inductance Ls, secondary building-out capacitor Cs and equivalent load impedance Z _lthe three is connected to form the secondary resonant tank successively;

Described former limit circuit also is provided with current sensing means, and this current sensing means is for detection of the electric current in described former limit resonant inductance Lp;

S2: controller cuts off switch S, only allows the first capacitor C 1 access former limit circuit, and DC power supply is carried 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 the first effective value of former limit circuital current and the first operating frequency is sent in described controller;

S4: controller Closing Switch S, make the first capacitor C 1 and the second capacitor C 2 former limit of rear access in parallel circuit, DC power supply is carried out direct current supply to former limit circuit, and the operating frequency that controller is regulated inverter makes former limit circuit enter resonance condition;

S5: current sensing means detects the electric current of former limit circuit and the second effective value of former limit circuital current and the second operating frequency is transferred in described controller;

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

2. voltage-type wireless power supply system load recognition methods according to claim 1 is characterized in that: the impedance equation that described controller is set up according to the first effective value, the first operating frequency, the second effective value and the second operating frequency is:

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

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

ImZ _r1+ω ₁L _P-1/ω ₁C ₁＝0

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

Wherein, Rp is primary coil internal resistance and electric capacity internal resistance sum, and Rs is the secondary coil internal resistance, u _pfor the voltage of inverter bridge output, I _p1for the first effective value with primary current, I _p2for the second effective value of primary current, ω ₁be the first operating frequency, ω ₂it is the second operating frequency.

3. a voltage-type wireless power supply system load recognition system, is characterized in that: comprise voltage-type IPT system, current sensing means and controller;

Described voltage-type IPT system is comprised of former limit circuit and secondary circuit, described former limit circuit is provided with the former limit resonant tank of DC power supply, full-bridge inverter and former limit resonant inductance Lp and former limit building-out capacitor Cp composition, described former limit building-out capacitor Cp comprises the first capacitor C 1 and the second capacitor C 2 in parallel, described the second capacitor C 2 is controlled and is realized connecting and cutting off by switch S, and described switch S is connected with controller;

Described secondary circuit comprises secondary resonant inductance Ls, secondary building-out capacitor Cs and equivalent load impedance Z _l, described secondary resonant inductance Ls, secondary building-out capacitor Cs and equivalent load impedance Z _lthe three is connected to form the secondary resonant tank successively;

Described current sensing means is for detection of the first effective value, the first operating frequency, the second effective value and second operating frequency of former limit circuital current, controller is set up impedance equation according to the first effective value, the first operating frequency, the second effective value and second operating frequency of former limit circuital current, asks for equivalent load impedance Z _l.

4. voltage-type wireless power supply system load recognition system according to claim 3, it is characterized in that: described current sensing means is provided with current transformer, this current transformer is for obtaining the current waveform of former limit circuit resonance state, at the output of current transformer, is connected with respectively resonance current frequency detecting unit, resonance current effective value value sampling unit and resonance current zero passage sampling unit.

5. voltage-type wireless power supply system load recognition system according to claim 4, it is characterized in that: described controller comprises frequency adjustment unit and load recognition unit, the frequency that the voltage of full-bridge inverter output is regulated according to the current zero-crossing signal of described resonance current zero passage sampling unit collection in described frequency adjustment unit makes former limit circuit enter resonance condition, described load recognition unit is connected with described resonance current effective value sampling unit with described resonance current frequency detecting unit respectively, for setting up impedance equation, load is identified and exported.

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