CN104362770A - Power signal parallel transfer circuit for ECPT (electric-field coupled power transfer) and control method of power signal parallel transfer circuit - Google Patents

Abstract

The invention discloses a power signal parallel transfer circuit for an ECPT (electric-field coupled power transfer) and a control method of the power signal parallel transfer circuit. A primary side part of the power signal parallel transfer circuit comprises a power circuit, a high-frequency inverter circuit, a tuning circuit and a pair of emission electrodes. A secondary side part comprises a pair of receiving electrodes, a rectifier-filter circuit and a load circuit. The power signal parallel transfer circuit is characterized in that a signal loading circuit is arranged between the tuning circuit and one of the emission electrodes, a signal pick-up circuit is arranged on the primary side part, the signal loading circuit loads a square signal to the emission electrode and is provided with a modulator circuit, the modulator circuit modulates duty ratio of the square signal according to a signal sequence, and the signal pick-up circuit is used for detecting an upper sharp peak and a lower sharp peak of a pick-up signal and modulates the signal sequence according to a ratio of space of the sharp peaks to signal cycle. The power signal parallel transfer circuit has the advantages that in the ECPT system, through a wireless power transmission channel, the signal transmission is achieved within a wide frequency bandwidth range, and signal transmission rate is improved.

Description

Energy signal parallel transmission circuit in ECPT and control method thereof

Technical field

The present invention relates to field coupled wireless power transmission (Electric-field Coupled Power Transfer, ECPT) technology, particularly relate to the energy signal parallel transmission circuit in a kind of ECPT and control method thereof.

Background technology

Wireless power transmission technology (Wireless Power Transfer, WPT) achieves the wireless power of power supply to load, has broken away from the constraint of direct electrical contact to equipment.The advantages such as field coupled wireless power transmission technology is light with it, Low emissivity, coupling mechanism are various become the new study hotspot in wireless power transmission field, and the circuit topology of system as shown in Figure 1.Domestic and international experts and scholars are around mobile robot, and biomedical implanting device, 3D Silicon-On-Insulator very lagre scale integrated circuit (VLSIC), many applications such as wireless charger and electric automobile launch research.

Current ECPT system more pays close attention to the wireless transmission of electric energy, but not only needs the wireless transmission of energy in a lot of application, also needs the parallel transmission realizing energy and signal.Chinese scholars launches research around the energy signal parallel transmission of WPT system, but mainly concentrates on ICPT system.Due to the difference of ICPT system and ECPT system, need to reanalyse ECPT system, design suitable energy parallel transmission method for system performance.

Summary of the invention

For the defect of prior art, the present invention carries out modeling analysis to the channel of ECPT system, propose the energy signal parallel transmission circuit in a kind of ECPT and control method thereof, this circuit carries out signal madulation based on square wave carrier duty ratio keying, and the channel utilizing wireless power transmission circuit to form, achieve the Signal transmissions under wide frequency bandwidth scope, promotion signal transmission rate, reduce information source switching frequency, simplify signal demodulating circuit, concrete technical scheme is as follows:

Energy signal parallel transmission circuit in a kind of ECPT, comprise former edge to divide and secondary part, its Central Plains edge is divided and is comprised power circuit, high-frequency inverter circuit, tuning circuit and a pair emission electrode, secondary part comprises a pair collecting electrode, current rectifying and wave filtering circuit and load circuit, its key is: between described tuning circuit and an emission electrode, be provided with signal loading circuit, secondary part is provided with signal pickup circuit, described signal loading circuit loads a square-wave signal on described emission electrode, modulation circuit is provided with in this signal loading circuit, this modulation circuit is according to the duty ratio of burst modulated square wave signal, described signal pickup circuit is for detecting the upper sharp pulse crest of pickoff signals and lower sharp pulse crest, and demodulate described burst according to upper and lower sharp pulse crest interval with the ratio of signal period.

In order to reduce the quantity of former limit switching tube and ensure wireless power transmission efficiency, described high-frequency inverter circuit is E class amplification circuit, and described tuning circuit is CLC tuning circuit.

For the ease of realizing the loading of square-wave signal, described signal loading circuit comprises a DC source, the first switching tube and second switch pipe, the low level end of DC source is connected on an output of tuning circuit, the low level end of this DC source is connected with emission electrode after being connected in series the first switching tube simultaneously, also be connected with described emission electrode after the high level end serial connection second switch pipe of DC source, described first switching tube and second switch pipe on off state under the driving of drive circuit is contrary.

In order to burst is modulated to duty cycle square wave signal, described drive circuit is connected with FPGA modulation circuit, and this FPGA modulation circuit exports the switching drive signal of duty ratio corresponding according to burst.

In order to simplify signal demodulating circuit, described signal pickup circuit adopts two coupling capacitance channel architecture, a pair coupling capacitance realizes transmission and the extraction of energy, and another adopts minimum capacitance to realize the impact reduced while Signal transmissions and extraction energy transferring on coupling capacitance.

In conjunction with foregoing circuit structure, the present invention also proposes the control method of the energy signal parallel transmission circuit in a kind of ECPT, and its key is:

Divide in former edge, the square-wave signal that burst to be modulated to duty ratio corresponding according to mapping relations one by one by modulation circuit is loaded on an emission electrode;

At secondary part, signal pickup circuit extracts upper spike and lower spike from collecting electrode, and demodulates corresponding burst according to upper and lower spike interval with the ratio of signal period.

As preferably, former edge divides the square-wave signal frequency of loading to be between 1kHz-2MHz.

Remarkable result of the present invention is:

The present invention is directed to channel band existing for current WPT system energy signal parallel transmission and transmission rate limited, and be applied to the problems such as small-power occasion more and propose energy signal parallel transmission circuit in ECPT and control method thereof, take square-wave signal as signal carrier, according to the square wave carrier signal that carrier modulation becomes duty ratio different by burst, realize signal madulation, can be that signal madulation is entered energy channel by information source by half-bridge circuit, the single channel realized from former limit to secondary transmits; At secondary by detecting sharp pulse crest and lower sharp pulse crest, pulse signal being converted into square-wave signal, then demodulating burst according to duty cycle square wave, having widened channel width; Multilevel code is adopted to improve signal transmission rate, reduce information source switching frequency; By improving coupling mechanism, simplify demodulator circuit.

Accompanying drawing explanation

Fig. 1 is the topology diagram of ECPT Circuits System;

Fig. 2 is the schematic block circuit diagram of signal loading circuit of the present invention;

Fig. 3 is the channel equivalent circuit diagram of Fig. 2;

Fig. 4 is that the frequency response Bode of channel schemes;

Fig. 5 is square wave carrier input waveform and output voltage waveform;

Fig. 6 is the circuit theory diagrams of signal loading circuit in specific embodiment;

Fig. 7 is that the structure of picking up signal coupling machine improves schematic diagram

Fig. 8 is the circuit theory diagrams of two coupling capacitance structure;

Fig. 9 is ECPT system capacity test waveform figure;

Figure 10 is system testing oscillogram under different carrier frequencies;

Figure 11 is the system testing oscillogram of different duty under same frequency.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention and operation principle are described in further detail.

As Fig. 1, shown in Fig. 2, energy signal parallel transmission circuit in a kind of ECPT, comprise former edge to divide and secondary part, its Central Plains edge is divided and is comprised power circuit, high-frequency inverter circuit, tuning circuit and a pair emission electrode, and secondary part comprises a pair collecting electrode, current rectifying and wave filtering circuit and load circuit, in this example, power circuit shown in figure is Vin, and high-frequency inverter circuit is that the E class amplification circuit built by inductance L and switch element S realizes, and tuning circuit is by electric capacity C _n1, inductance L _nand electric capacity C _n2the CLC tuning circuit built, in order to realize the parallel transmission of energy and signal in ECPT system, signal modulation circuit is provided with between described tuning circuit and an emission electrode, secondary part is provided with signal demodulating circuit, described signal loading circuit loads a square-wave signal on described emission electrode, modulation circuit is provided with in this signal loading circuit, this modulation circuit is according to the duty ratio of burst modulated square wave signal, described signal pickup circuit is for detecting the upper sharp pulse crest of pickoff signals and lower sharp pulse crest, and demodulate described burst according to upper and lower sharp pulse crest interval with the ratio of signal period.

Signal transmission in the path of ECPT transmitting energy, channel directly will affect signal transmission quality to the attenuation characteristic of signal.Therefore it is very important to the specificity analysis of channel.Consider that the components and parts in circuit are ideal component, DC source internal resistance is considered as zero.To simplify the analysis, desirable resistive load R is considered to by the current rectifying and wave filtering circuit in circuit and with electric loading is unified _o.In the break-make putting switching tube S before this, system is divided into two operation modes, the equivalent circuit diagram of channel as shown in Figure 3.

Consider signal voltage u ₁for channel input, channel exports as load current i _o.So the channel model under each mode can be expressed as

$\left\{\begin{array}{c}{\stackrel{\·}{x}}_i=A_i{x}_i+B_{i}u\\ y_i=C_i{x}_i+D_{i}u\end{array}\right.,i\∈\left[\mathrm{1,2}\right]$

S conducting:

$A_1=\left[\begin{array}{ccc}-\frac{1}{R_o{C}_{N2}}& \frac{1}{C_{N2}}& \frac{1}{R_o{C}_{N2}}\\ -\frac{1}{L_N}& 0& 0\\ \frac{1}{R_o{C}_S}& 0& -\frac{1}{R_o{C}_S}\end{array}\right],B_1=\left[\begin{array}{c}\frac{1}{R_o{C}_{N2}}\\ 0\\ -\frac{1}{R_o{C}_S}\end{array}\right]$

C ₁＝[1 0 -1],D ₁＝-1

S turns off:

$A_2=\left[\begin{array}{ccccc}0& 0& \frac{1}{C_{N1}}& \frac{1}{C_{N2}}& 0\\ 0& -\frac{1}{R_o{C}_{N2}}& 0& \frac{1}{C_{N2}}& \frac{1}{R_o{C}_{N2}}\\ -\frac{1}{L}& 0& 0& 0& 0\\ \frac{1}{L_N}& -\frac{1}{L_N}& 0& 0& 0\\ 0& \frac{1}{R_o{C}_S}& 0& 0& -\frac{1}{R_o{C}_S}\end{array}\right],B_2=\left[\begin{array}{c}0\\ \frac{1}{R_o{C}_{N2}}\\ 0\\ 0\\ -\frac{1}{R_o{C}_S}\end{array}\right]$

C ₂＝[0 1 0 0 -1],D ₂＝-1

Wherein, x ₁=[u _cN2, i _lN, u _cS] ^t, x ₂=[u _cN1, u _cN2, i _l, i _lN, u _cS] ^t.The state space equation corresponding by above-mentioned two kinds of mode, with the data in table 1 for system emulation parameter, the channel model Bode drawing mode 1 and mode 2 schemes, and obtains the frequency domain response characteristic of channel as shown in Figure 4.

Table 1 ECPT circuit parameter

In Fig. 4, the frequency domain response of two kinds of mode lower channels is comparatively similar.Get fading channel and be less than 5% for undamped border, two kinds of zero-decrement initial angle frequencies omega of mode lower channel ₁ ^*=ω ₂ ^*=1.16 × 10 ⁷rad/s.For reducing channel to the attenuation of signal, the signal angular frequency of selection need meet ω >max{ ω ₁ ^*, ω ₂ ^*.The channel frequency of this system visible is limited in higher frequency range, channel width and signal transmission rate-constrained.

For solving the problem of channel band and signal transmission rate-constrained, this section provides a kind of method utilizing square wave carrier duty ratio modulation mode to realize energy and signal parallel to transmit based on ECPT system.Due to current variable i in five state variables _lN, i _lmuch smaller than voltage quantities u _cN1, u _cN2, u _cS, therefore state variable i _lN, i _lcan ignore.Thus the state-space model under two kinds of mode all can be reduced to

$A_{\mathrm{sim}}=\left[\begin{array}{cc}-\frac{1}{R_o{C}_{N2}}& \frac{1}{R_o{C}_{N2}}\\ \frac{1}{R_o{C}_S}& -\frac{1}{R_o{C}_S}\end{array}\right],B_{\mathrm{sim}}=\left[\begin{array}{c}\frac{1}{R_o{C}_{N2}}\\ -\frac{1}{R_o{C}_S}\end{array}\right]$

C _sim＝[1 -1],D _sim＝-1

State variable is [u _cN2, u _cS] ^t.Separate state-space expression can obtain:

$\frac{\mathrm{d\Δu}}{\mathrm{dt}}+\frac{1}{R_o{C}_{\mathrm{eq}}}\mathrm{\Δu}-\frac{1}{R_o{C}_{\mathrm{eq}}}u$

Wherein

Δu＝u _CN2-u _CS

$\frac{1}{R_o{C}_{\mathrm{eq}}}=\frac{1}{R_o{C}_{N2}}+\frac{1}{R_o{C}_S}$

Solve

According to above-mentioned model solution, when can show that carrier wave is any duty ratio, the output voltage waveforms of system as shown in Figure 5.

In Fig. 5, when square-wave signal is by channel, the voltage u that system load is picked up _rofor positive negative pulse stuffing signal, positive pulse comes across square wave rising edge, and negative pulse comes across square wave trailing edge.So the interval of spike up and down that the duty ratio of the square-wave signal carrier wave that former limit loads and secondary pick up is equal with the ratio in cycle, namely this characteristic overcomes the bandwidth restriction of channel.In addition according to multilevel code modulation, N decile is divided into by duty ratio 0-1, so signal transmission speed can promote log under identical information source switching frequency ₂n times, or under identical signal transmission rate conditions, information source frequency reduces log ₂n doubly.

According to above-mentioned principle analysis, in specific implementation process, described signal loading circuit is according to circuit structure design as shown with 7, comprise a DC source, the first switching tube and second switch pipe, the low level end of DC source is connected on an output of tuning circuit, the low level end of this DC source is connected with emission electrode after being connected in series the first switching tube simultaneously, also be connected with described emission electrode after the high level end serial connection second switch pipe of DC source, described first switching tube and second switch pipe on off state under the driving of drive circuit is contrary.

As can be seen from Figure 6, by FPGA control switch S _d1, S _d2alternate conduction change the terminal voltage of this module, loaded by square wave carrier in major loop, two-way exchange electric current in loop is by a in Fig. 6, and b loop stream is through signal loading module, and bi-directional path internal resistance all can be considered 0, therefore the impact of this module on energy transferring is less.

In addition, by known resistance R _oterminal voltage u _ropeak value only depend on carrier wave and square-wave signal u _inpeak value, have nothing to do with equivalent capacity in loop (affecting by coupling capacitance) and load resistance; But load R when coupling capacitance diminishes _oenergy voltage waveform will decay.Two coupling capacitance mode (as shown in Figure 7) is adopted, by a less signal coupling electric capacity C based in these 2 embodiments _dby signal transmission to R _dfilter energy voltage waveform, realizes energy and Signal separator simultaneously.

As shown in Figure 7, coupling capacitance carries out modeling again to two coupling capacitance channel after improving

$\left\{\begin{array}{c}\stackrel{\·}{x}=\mathrm{Ax}+{\mathrm{Bu}}_{\mathrm{in}}\\ u_{\mathrm{RE}}=u_{\mathrm{in}}-u_{\mathrm{Ceq}}-u_{\mathrm{CE}}\\ u_{\mathrm{RD}}=u_{\mathrm{in}}-u_{\mathrm{Ceq}}-u_{\mathrm{CD}}\end{array}\right.$

Carry out computing in conjunction with actual parameter, obtain waveform as shown in Figure 8, by the u in figure _sand u _rDthe characteristic of channel of the visible two coupling mechanism system of waveform and the property class of original system channel seemingly, still keep the characteristic of original system.And obtain R _dupper signal voltage u _rDafter hysteresis loop comparator can be utilized further pulse signal to be reverted to square-wave signal containing duty cycle information.After this be digital quantity by processor by signals revivification, i.e. the demodulation of settling signal.

Based on foregoing description, core of the present invention is also the control method of the energy signal parallel transmission circuit proposed in a kind of ECPT, is specifically:

Divide in former edge, the square-wave signal that burst to be modulated to duty ratio corresponding according to mapping relations one by one by modulation circuit is loaded on an emission electrode;

At secondary part, signal pickup circuit extracts upper spike and lower spike from collecting electrode, and demodulates corresponding burst according to upper and lower spike interval with the ratio of signal period.

In implementation process, former edge divides the square-wave signal frequency of loading to be between 1kHz-2MHz.

In conjunction with specific experiment, feasibility of the present invention and conspicuousness are described further again below.

Energy transferring part builds side circuit according to the ECPT circuit topology of Fig. 1, and system parameter setting is as shown in table 1.Fig. 9 is the energy experimental waveform of ECPT system, and as can be seen from Figure, system operating frequency is about 259.7kHz.Load is that under 500 Ω, load peak voltage is 272V, and namely picking up power is 73.98W.

The square wave carrier frequency of signal transmission part is produced by FPGA, loads on switch controlled end by drive circuit.Figure 10 is ECPT system signal experimental waveform, and getting duty ratio is 50% for example, and recording system signal transfer rate can reach 5.6Mbit/s.Under low frequency (such as 10kHz, is generally not less than 1kHz), signal transmission is in good condition, because the characteristic of channel makes signal transmission undesirable when frequency is greater than 2MHz.The mode modulation signal of many duty ratios keying can be adopted to improve signal rate in low-frequency range, as shown in figure 11 simultaneously.In figure, square wave carrier frequency is about 1MHz, and get duty ratio 0.2 and 0.8 for example, system signal demodulation effect is better.

Finally it should be noted that, the present embodiment take square-wave signal as signal carrier, realizes signal madulation by changing carrier duty cycle.Be that signal madulation is entered energy channel by information source with half-bridge circuit, the single channel realized from former limit to secondary transmits; Be demodulation waveforms with impulse waveform, widened channel width; Multilevel code is adopted to improve signal transmission rate, reduce information source switching frequency; By improving coupling mechanism, simplify signal demodulating circuit; In addition the method is less on energy transferring impact.In embody rule process, person skilled can burst as required, selects different parameters, can promotion signal transfer rate, also can reduce information source switching frequency.Such as former edge divides only needs to transmit " 0 ", " 1 " two kinds of signals to secondary part, duty ratio so can be selected to be the corresponding corresponding signal of square wave carrier of " 0.2 " and " 0.8 ", if former edge divides needs to secondary part transmission " 00 ", " 01 ", " 10 ", " 11 " four kinds of signals, duty ratio so can be selected to be the corresponding corresponding signal of square wave carrier of " 0.2 ", " 0.4 ", " 0.6 " and " 0.8 ", the like, improve effectiveness.

Claims (7)

1. the energy signal parallel transmission circuit in an ECPT, comprise former edge to divide and secondary part, its Central Plains edge is divided and is comprised power circuit, high-frequency inverter circuit, tuning circuit and a pair emission electrode, secondary part comprises a pair collecting electrode, current rectifying and wave filtering circuit and load circuit, it is characterized in that: between described tuning circuit and an emission electrode, be provided with signal loading circuit, secondary part is provided with signal pickup circuit, described signal loading circuit loads a square-wave signal on described emission electrode, modulation circuit is provided with in this signal loading circuit, this modulation circuit is according to the duty ratio of burst modulated square wave signal, described signal pickup circuit is for detecting the upper sharp pulse crest of pickoff signals and lower sharp pulse crest, and demodulate described burst according to upper and lower sharp pulse crest interval with the ratio of signal period.

2. the energy signal parallel transmission circuit in ECPT according to claim 1, is characterized in that: described high-frequency inverter circuit is E class amplification circuit, and described tuning circuit is CLC tuning circuit.

3. the energy signal parallel transmission circuit in ECPT according to claim 1 and 2, it is characterized in that: described signal loading circuit comprises a DC source, the first switching tube and second switch pipe, the low level end of DC source is connected on an output of tuning circuit, the low level end of this DC source is connected with emission electrode after being connected in series the first switching tube simultaneously, also be connected with described emission electrode after the high level end serial connection second switch pipe of DC source, described first switching tube and second switch pipe on off state under the driving of drive circuit is contrary.

4. the energy signal parallel transmission circuit in ECPT according to claim 3, is characterized in that: described drive circuit is connected with FPGA modulation circuit, and this FPGA modulation circuit exports the switching drive signal of duty ratio corresponding according to burst.

5. the energy signal parallel transmission circuit in ECPT according to claim 3, is characterized in that: described signal pickup circuit adopts two coupling capacitance channel architecture.

6. the control method of the energy signal parallel transmission circuit in ECPT as claimed in claim 1, is characterized in that:

Divide in former edge, the square-wave signal that burst to be modulated to duty ratio corresponding according to mapping relations one by one by modulation circuit is loaded on an emission electrode;

At secondary part, signal pickup circuit extracts upper spike and lower spike from collecting electrode, and demodulates corresponding burst according to upper and lower spike interval with the ratio of signal period.

7. the control method of the energy signal parallel transmission circuit in ECPT as claimed in claim 6, is characterized in that: former edge divides the square-wave signal frequency of loading to be between 1kHz-2MHz.