CN115102304A - Two-way electric field coupling wireless power transmission system and control method thereof - Google Patents

Abstract

The invention discloses a two-way electric field coupled wireless power transmission system and a control method thereof. The system includes a primary side circuit and a secondary side circuit. Both the primary side circuit and the secondary side circuit include a power interface, a converter, a resonance network and a pair of metal poles. The primary side controller is connected to the primary side converter, and the secondary side controller is connected to the secondary side converter. The primary side circuit and the secondary side circuit are bidirectionally realized through the primary side metal electrode plate and the secondary side metal electrode plate. Electric field coupled wireless power transmission, the primary side controller controls the phase shift variable of the primary side converter, the secondary side controller controls the phase shift variable of the secondary side converter, the relative phase angle of the primary and secondary side output voltage is θ, when 0 When °<θ<180°, the system forward power transmission is realized, and when ‑180°<θ<0°, the system reverse power transmission is realized. The present invention enables the magnitude and direction of power flow to be regulated and controlled by the phase or amplitude of the voltages generated by the primary and secondary side converters, and is effectively suitable for power flow regulation in a two-way electric field coupled wireless power transmission system.

Description

Two-way electric field coupling wireless power transmission system and control method thereof

technical field

The present invention relates to the technical field of wireless power transmission, in particular to a two-way electric field coupling type wireless power transmission system and a control method thereof.

Background technique

Wireless Power Transfer (WPT) is a new type of technology that uses power electronic technology to realize power transmission through media such as magnetic field, electric field, microwave or laser, which solves the problem of unsafe and inflexible power contacts. In the past few years, Inductive Power Transfer (IPT) has received extensive attention, and its theory and technology have been widely studied and applied. However, due to electromagnetic shielding, the IPT system cannot conduct power transmission through metal obstacles, and the power loss is severe when the metal object is close to the magnetic field. Electric field coupled wireless power transfer (Capacitive Power Transfer, CPT) technology uses electric field as the energy transmission medium and does not consider metal interference, which has attracted extensive attention of experts and scholars. The electric field of the CPT system is mainly concentrated between the coupling plates, and the surrounding electromagnetic interference is greatly reduced.

Since the coupling capacitance of a CPT system is usually small and needs to work at high frequencies, its performance is closely related to the circuit topology using capacitive couplers. Currently commonly used resonant topologies include double-sided LC, double-sided LCL, double-sided LCLC, and double-sided CLCL, etc., to meet high-power long-distance requirements and a wide range of applications from low-power electronic devices to high-power electric vehicles. There are some problems in the double-sided LCL resonant topology, such as the large inductance in series, which leads to the increase of the system volume, the large equivalent series resistance of the inductor, and the excessive heat loss; the double-sided LCLC or CLCL resonant topology has too many components and high The order system parameters have obvious influence and the robustness is poor; while the double-sided LC resonant network, in addition to its simple structure, only needs to install two external passive components on the secondary side, which helps to save space. Second, it can be applied to short-range and long-range applications, and the transmission efficiency can be optimized to a relatively high level. However, the CPT systems proposed so far are all specifically aimed at unidirectional power flow transmission, and are not suitable for bidirectional power flow transmission.

SUMMARY OF THE INVENTION

The invention provides a two-way electric field coupled wireless power transmission system and a control method thereof, so that the magnitude and direction of the power flow between electric vehicles or electrical equipment can pass through the phase or amplitude of the voltage generated by the primary and secondary side converters. It can be effectively applied to the power flow regulation of the two-way electric field coupled wireless power transmission system.

所述副边控制器控制所述副边变换器产生延迟相位δ和桥间相移

使得原、副边输出电压的相对相位角为θ，当0°<θ<180°时，实现系统正向功率传输，当-180°<θ<0°时，实现系统反向功率传输。The invention provides a two-way electric field coupling type wireless power transmission system, comprising a primary side circuit and a secondary side circuit, the primary side circuit comprising a primary side power supply interface, a primary side converter, a primary side resonance network and a pair of primary side metal Plate, the secondary circuit includes a secondary power interface, a secondary converter, a secondary resonance network and a pair of secondary metal plates, a primary controller is connected to the primary converter, and a primary controller is connected to the primary converter. The secondary side converter is connected with the secondary side controller, and the two-way electric field coupled wireless energy is realized between the primary side circuit and the secondary side circuit through the pair of primary side metal plates and the pair of secondary side metal plates transmission, wherein: the primary side controller controls the primary side converter to generate an inter-bridge phase shift

The secondary side controller controls the secondary side converter to generate a delayed phase δ and an inter-bridge phase shift

The relative phase angle of the primary and secondary output voltages is θ. When 0°<θ<180°, the system forward power transmission is realized, and when -180°<θ<0°, the system reverse power transmission is realized.

Further, a primary filter capacitor C _d is arranged between the primary side power supply interface and the primary side converter, and a secondary side filter capacitor C _o is arranged between the secondary side power supply interface and the secondary side converter. .

Further, both the primary resonance network and the secondary resonance network adopt an LC resonance network, wherein: the primary resonance network includes a primary resonance inductor L ₁ and a primary compensation capacitor C _f1 , and the secondary resonance network includes a primary resonance inductance L 1 and a primary compensation capacitor C f1 . The network includes secondary resonant inductor L ₂ and secondary compensation capacitor C _f2 .

Further, the parameters of each electrical component in the primary resonance network and the secondary resonance network satisfy:

Among them, ω is the operating angular frequency of the system, L ₁ is the self-inductance of the primary resonant inductor L ₁ , L ₂ is the self-inductance of the secondary resonant inductor L ₂ , and C ₁ is the equivalent of the primary resonant circuit in the system equivalent current source model. Self-capacitance, C ₂ is the equivalent self-capacitance of the secondary resonant circuit in the system equivalent current source model, C _M is the equivalent mutual capacitance of the electric field coupling mechanism formed by the pair of primary metal plates and the pair of secondary metal plates capacitance.

其中：Further, the equivalent self-capacitance of the primary resonant circuit C ₁ =C _in1 +C _f1 , the equivalent self-capacitance of the secondary resonant circuit C ₂ =C _in2 +C _f2 , the equivalent mutual capacitance of the electric field coupling mechanism

in:

C _f1 is the capacitance value of the primary side compensation capacitor C _f1 , and C _f2 is the capacitance value of the secondary side compensation capacitor C _f2 ;

Intermediate variables

Intermediate variables

The pair of primary metal pole plates includes pole plate P ₁ and pole plate P ₂ , and the pair of secondary metal pole plates includes pole plate P ₃ and pole plate P ₄ , then:

C ₁₂ represents the equivalent capacitance between plate P ₁ and plate P ₂ , C ₁₃ represents the equivalent capacitance between plate P ₁ and plate P ₃ , and C ₁₄ represents the equivalent capacitance between plate P ₁ and plate P _{4 The} equivalent capacitance between P2 and P3, _C23 indicates the equivalent capacitance between P2 and _P3 , _C24 indicates the equivalent capacitance between P2 and _P4 , and _C34 indicates the equivalent capacitance between P2 and P4 _. Equivalent capacitance between _P3 and plate P4 _.

Further, both the primary-side converter and the secondary-side converter use full-bridge reversible rectifiers, wherein the primary-side converter includes a switch S1, a switch S2, a switch S3, and a switch S4, and the The secondary side converter includes a switch tube S5, a switch tube S6, a switch tube S7, and a switch tube S8.

的约束关系控制所述原边变换器和所述副边变换器，其中V_d表示所述原边电源接口的直流电压，V_o表示所述副边电源接口的直流电压。Further, the primary side controller and the secondary side controller according to the requirements of the active power _{Pr and reactive power Q r received} by the secondary side converter, according to:

The constraint relationship of , controls the primary side converter and the secondary side converter, where V _d represents the DC voltage of the primary side power supply interface, and V _o represents the DC voltage of the secondary side power supply interface.

Further, the primary side controller and the secondary side controller control the primary side converter and the secondary side converter in a manner of θ=±90° to realize maximum forward power transmission or reverse power transmission.

Further, the outputs of the primary and secondary circuits are connected to electronic equipment and absorb or transmit power, and the output interfaces at both ends are represented by a DC power source. During forward power transmission of the system, the primary power supply outputs energy, and the secondary power supply receives energy, and during reverse power transmission of the system, the secondary power supply outputs energy, and the primary power supply receives energy. The present invention also provides a control method for the above-mentioned bidirectional electric field coupled wireless power transmission system, comprising the following steps:

S1. The primary side converter and the secondary side converter are connected by wireless communication, and the switching frequency, the output voltage and expected power of the primary side converter are initialized at the same time;

得到期望的原边变换器输出电压V_p；S2. Adjust the primary side converter to generate a phase shift between bridges

Obtain the desired primary-side converter output voltage V _p ;

S3. Obtain the actual output power P of the system, and determine whether the actual output power P of the system is greater than the set power;

以满足系统实际功率需求；S4. If the actual output power P of the system is not equal to the set power, adjust the secondary side converter to generate the delayed phase δ and the inter-bridge phase shift

To meet the actual power requirements of the system;

S5. If the actual output power P of the system is equal to the set power, wait for the power to reach a steady state, and the final desired power is equal to the actual output power.

The beneficial effects of the present invention are:

The invention proposes a two-way electric field coupled wireless power transmission system suitable for simultaneous wireless charging and discharging of electrical equipment. Power can flow in both directions and is suitable for various equipment that needs to be charged. When the power grid cannot supply power to the equipment in time, it can By supplying power to the required equipment through other equipment, on the one hand, it can supply power to it in a timely and effective manner, and on the other hand, it saves electricity and does not waste it. The magnitude and direction of the power flow between vehicles or electrical equipment can be adjusted and controlled by the phase or amplitude of the voltage generated by the primary and secondary side converters, which can be effectively applied to the power flow regulation of the two-way electric field coupled wireless power transmission system .

Description of drawings

FIG. 1 is a circuit topology diagram of a bidirectional electric field coupled wireless power transmission system of the present invention.

FIG. 2 is a simplified circuit diagram of an equivalent current source model of the bidirectional electric field coupled wireless power transmission system of the present invention.

3 is a switching timing diagram of the primary and secondary side converters of the bidirectional electric field coupled wireless power transmission system of the present invention.

FIG. 4 is an equivalent circuit diagram of the bidirectional electric field coupled wireless power transmission system of the LC resonant network of the present invention.

FIG. 5 is a phase relationship diagram of the relative phase angle θ between the power flow and the output voltage of the converter in the present invention.

FIG. 6 is a diagram of a phase shift control strategy of the primary and secondary side converters in the present invention.

FIG. 7 is a schematic flowchart of a power flow control method in the present invention.

The realization, functional characteristics and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

Detailed ways

It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

In order to facilitate the realization of energy supply and demand between devices, the circuit topology of a typical BCPT (Bidirectional Capacitive Power Transfer, BCPT) system based on a double-sided LC resonant network is shown in Figure 1. Under the action of the interactive electric field, wireless energy transmission between the plates is realized. The outputs of the primary and secondary circuits are connected to the electronic equipment and absorb or transmit power. The output interfaces at both ends are represented by a DC power supply. The primary and receiver circuits use nearly identical electrical equipment to facilitate bidirectional power flow between the devices, including a full-bridge converter (reversible rectifier) and a double-sided LC resonant network. Each converter operates in inverter or rectifier mode, depending on the direction of power flow. The magnitude and relative phase angle of the output voltage of the full-bridge converter will determine the magnitude and direction of power between consumers.

所述副边控制器控制所述副边变换器产生延迟相位δ和桥间相移

使得原、副边输出电压的相对相位角为θ，当0°<θ<180°时，实现系统正向功率传输，当-180°<θ<0°时，实现系统反向功率传输。A two-way electric field coupling wireless power transmission system includes a primary side circuit and a secondary side circuit, the primary side circuit includes a primary side power supply interface, a primary side converter, a primary side resonance network and a pair of primary side metal plates, the secondary side The side circuit includes a secondary side power interface, a secondary side converter, a secondary side resonant network and a pair of secondary side metal plates. A primary side controller is connected to the primary side converter, and a primary side controller is connected to the secondary side converter. There is a secondary side controller, and the two-way electric field coupling wireless power transmission is realized between the primary side circuit and the secondary side circuit through the pair of primary side metal plates and the pair of secondary side metal plates, wherein: the The primary side controller controls the primary side converter to generate an inter-bridge phase shift

The secondary side controller controls the secondary side converter to generate a delayed phase δ and an inter-bridge phase shift

The relative phase angle of the primary and secondary output voltages is θ. When 0°<θ<180°, the system forward power transmission is realized, and when -180°<θ<0°, the system reverse power transmission is realized.

A primary filter capacitor C _d is arranged between the primary side power supply interface and the primary side converter, and a secondary side filter capacitor C _o is arranged between the secondary side power supply interface and the secondary side converter. Both the primary resonance network and the secondary resonance network use an LC resonance network, wherein: the primary resonance network includes a primary resonance inductance L ₁ and a primary compensation capacitor C _f1 , and the secondary resonance network includes a secondary resonance network. Side resonant inductor L ₂ and secondary side compensation capacitor C _f2 .

The parameters of each electrical component in the primary resonant network and the secondary resonant network satisfy (that is, the frequency formula of the LC resonant circuit is):

Among them, ω is the operating angular frequency of the system, L ₁ is the self-inductance of the primary resonant inductor L ₁ , L ₂ is the self-inductance of the secondary resonant inductor L ₂ , and C ₁ is the equivalent of the primary resonant circuit in the system equivalent current source model. Self-capacitance, C ₂ is the equivalent self-capacitance of the secondary resonant circuit in the system equivalent current source model, C _M is the equivalent mutual capacitance of the electric field coupling mechanism formed by the pair of primary metal plates and the pair of secondary metal plates capacitance.

In Figure 1, L ₁ and L ₂ are coil self-inductances, and C _f1 and C _f2 are resonance compensation capacitors. Both the primary-side converter and the secondary-side converter use full-bridge reversible rectifiers, wherein the primary-side converter includes a switch S1, a switch S2, a switch S3 and a switch S4, and the secondary converter includes Switch tube S5, switch tube S6, switch tube S7, switch tube S8. The resonant tank adopts a double-sided LC structure, v _p and v _r are the output voltages of the primary and secondary side converters, and i ₁ and i ₂ are the currents of the resonant tank. V _d and V _o are the DC voltages on both sides, respectively.

A simplified circuit diagram of the equivalent current source model of the BCPT system is shown in Figure 2. The current source associated with the two capacitor voltages represents the capacitive coupling between the primary and secondary sides. The equivalent self-capacitance of the primary side and the secondary side is expressed as: the equivalent self-capacitance of the primary side resonant circuit C ₁ =C _in1 +C _f1 , the equivalent self-capacitance of the secondary side resonant circuit C ₂ =C _in2 +C _f2 ,

The capacitive coupling coefficient is:

其中：C_f1为原边补偿电容C_f1的电容值，C_f2为副边补偿电容C_f2的电容值，中间变量

中间变量

其中，一对原边金属极板包括极板P₁和极板P₂，一对副边金属极板包括极板P₃和极板P₄，则：C₁₂表示极板P₁和极板P₂之间的等效电容，C₁₃表示极板P₁和极板P₃之间的等效电容，C₁₄表示极板P₁和极板P₄之间的等效电容，C₂₃表示极板P₂和极板P₃之间的等效电容，C₂₄表示极板P₂和极板P₄之间的等效电容，C₃₄表示极板P₃和极板P₄之间的等效电容。The equivalent mutual capacitance of the electric field coupling mechanism

Among them: C _f1 is the capacitance value of the primary side compensation capacitor C _f1 , C _f2 is the capacitance value of the secondary side compensation capacitor C _f2 , and the intermediate variable

Intermediate variables

Wherein, a pair of primary metal plates includes plate P ₁ and plate P ₂ , and a pair of secondary metal plates includes plate P ₃ and plate P ₄ , then: C ₁₂ represents plate P ₁ and plate P 4 Equivalent capacitance between P ₂ , C ₁₃ represents the equivalent capacitance between plate P ₁ and plate P ₃ , C ₁₄ represents the equivalent capacitance between plate P ₁ and plate P ₄ , C ₂₃ represents the equivalent capacitance between plate P 1 and plate P 4 Equivalent capacitance between plate P ₂ and plate P ₃ , C ₂₄ represents the equivalent capacitance between plate P ₂ and plate P ₄ , C ₃₄ represents the equivalent capacitance between plate P ₃ and plate P ₄ equivalent capacitance.

副边控制器对副边变换器产生桥间相移

以此调整原、副边变换器输出电压的大小。另外，在原边和副边变换器的驱动信号之间还可以设置延迟相位δ。通常，可以调整副边的延迟相位δ和桥间相移

来得到系统所需的功率流大小和方向。系统的原、副边变换器的开关切换时序图如图3所示。Both the primary and secondary side controllers adopt phase-shifting technology, and the power flow of the system is realized by adjusting the phase-shifting angle between the voltages of the converters and the output voltages of the two converters. The primary-side controller produces an inter-bridge phase shift to the primary-side converter

The secondary side controller produces the inter-bridge phase shift to the secondary side converter

In this way, the output voltage of the primary and secondary side converters is adjusted. In addition, a delay phase δ can also be set between the drive signals of the primary and secondary side converters. In general, the delayed phase δ and inter-bridge phase shift of the secondary side can be adjusted

to get the magnitude and direction of the power flow required by the system. The switching sequence diagram of the primary and secondary side converters of the system is shown in Figure 3.

和

原、副边变换器输出电压的相对相位差可以表示为θ，变换器输出电压可以通过傅立叶级数展开得出：As shown in Figure 3, the primary and secondary side converter switches (S1-S4, S5-S8) operate with a 50% duty cycle and switching frequency f to generate voltages v _p and v _r , and the primary and secondary side convert The phase difference between the two bridge arms of the converter is

and

The relative phase difference of the output voltage of the primary and secondary side converters can be expressed as θ, and the output voltage of the converter can be obtained by Fourier series expansion:

Among them, ω _s =2πf _s ;

Use the fundamental wave approximation to analyze the working principle of the circuit, as shown in Figure 4. The two converters are represented in an equivalent circuit by two controlled AC voltage sources. When the system converter switching angular frequency ω _s is equal to the system resonant frequency, based on Kirchhoff's voltage law, the current and voltage relationship of the BCPT system components shown in Figure 4 can be established as:

The system secondary-side converter output current I ₂ can be expressed as:

Through the resonance relationship in the frequency _formula of the LC resonant circuit, I can be simplified to get:

Ignoring the influence of the higher harmonics of the output voltage of the converter on the transmission power in the formula of the output voltage of the original and secondary side converters in the formula of the Fourier series expansion of the output voltage of the converter, the active power P _r and the reactive power received by the secondary side converter The formula for _Qr is:

的约束关系控制所述原边变换器和所述副边变换器，其中V_d表示所述原边电源接口的直流电压，V_o表示所述副边电源接口的直流电压。Therefore, the primary side controller and the secondary side controller according to the requirements of the active power P _r and reactive power Q _r received by the secondary side converter, according to:

The constraint relationship of , controls the primary side converter and the secondary side converter, where V _d represents the DC voltage of the primary side power supply interface, and V _o represents the DC voltage of the secondary side power supply interface.

和

及原、副边变换器输出电压相对相位角θ来调节。当0<θ<180°时,P_r<0，滞后的相对相位角使功率能够从原边传输到副边，系统正向传输功率；当-180°<θ<0时，P_r>0，超前的相对相位角使功率从副边到原边传输，系统反向传输功率；对于任何给定电压，所述原边控制器和所述副边控制器按照θ＝±90°的方式控制所述原边变换器和所述副边变换器实现最大正向功率传输或反向功率传输。如图5显示了功率流与变换器输出电压的相对相位角θ的相位关系图。因此，控制功率流的有效方法是通过调节变换器输出电压的相对相位角θ，使系统在两个方向上进行功率流传输。对于任何期望的功率流传输可以通过调制相位

的任何组合，以此可以控制变换器输出电压的相对相位角θ。According to the above formula, for the given circuit parameters and DC voltage of the system, the power of the secondary side of the system depends on the relative phase angle of the primary and secondary side output voltages. Therefore, the power size and direction of the system can be determined by the phase difference between the two bridge arms of the primary and secondary side converters

and

And the output voltage of the primary and secondary side converters is adjusted relative to the phase angle θ. When 0<θ<180°, P _r <0, the lagging relative phase angle enables power to be transmitted from the primary side to the secondary side, and the system transmits power forward; when -180°<θ<0, P _r >0 , the advanced relative phase angle makes the power transfer from the secondary side to the primary side, and the system transfers power in the reverse direction; for any given voltage, the primary side controller and the secondary side controller are controlled in a manner of θ=±90° The primary side converter and the secondary side converter enable maximum forward power transfer or reverse power transfer. Figure 5 shows a phase relationship diagram of the power flow versus the relative phase angle θ of the converter output voltage. Therefore, an effective way to control the power flow is to make the system perform power flow transfer in both directions by adjusting the relative phase angle θ of the output voltage of the converter. For any desired power flow transfer can be done by modulating the phase

Any combination of , so that the relative phase angle θ of the output voltage of the converter can be controlled.

The present invention also provides a power flow control method based on the above-mentioned bidirectional electric field coupled wireless power transmission system.

从而改变副边变换器电压大小和原副边变换器电压间的相对相位角θ，使得副边变换器工作在该相对相位角产生的电压时减小功率间的误差。变换器电压v_r超前或滞后电压v_p相位角θ，其中0<θ<π之间的相位角导致副边变换器作为整流器工作，向副边电池设备或电动汽车供电。当副边变换器在逆变器模式下工作时，相位角在-π<θ<0，副边的电池设备或电动汽车向原边电源供电。The primary-side full-bridge converter is driven by the primary-side controller in Figure 6. It has a triangular wave generator to generate a phase modulated square wave voltage _vp . The secondary side controller generates the inter-bridge phase shift by supplying the difference between the reference power _Pe and the actual power _Pr to the PI controller

Therefore, the relative phase angle θ between the voltage of the secondary side converter and the voltage of the primary and secondary side converters is changed, so that the error between the powers is reduced when the secondary side converter operates at the voltage generated by the relative phase angle. The converter voltage v _r leads or lags the voltage v _p by a phase angle θ, where phase angles between 0 < θ < π cause the secondary converter to operate as a rectifier, supplying power to secondary battery equipment or electric vehicles. When the secondary side converter works in inverter mode, the phase angle is -π<θ<0, and the battery equipment or electric vehicle on the secondary side supplies power to the primary side power supply.

用于调整原边变换器输出电压的幅值，进而可以调整系统输出额定电流i₂。副边控制器在副边变换器两个桥臂之间产生移相角

并产生副边变换器相对原边变换器支路之间的延迟相位δ。通常，调整副边延迟相位δ和桥间相移

就可以达到系统所需的功率流大小和方向。因此，基于移相控制，将来自原、副边控制器的相移变量(

和δ)转换为变换器开关管S1-S8的开关信号，有效地调整原、副边变换器电压的幅值和相位，以实现BCPT系统所需的功率流。Based on the control strategy shown in Figure 6, the output power of the system is regulated by adjusting the phase shift between the bridge arms of the converter and the voltages of the primary and secondary side converters. The primary side controller generates the phase shift angle between the two bridge arms of the primary side converter

It is used to adjust the amplitude of the output voltage of the primary side converter, and then the rated current i ₂ of the system output can be adjusted. The secondary controller generates the phase shift angle between the two legs of the secondary converter

And generate the delay phase δ between the secondary side converter relative to the primary side converter branch. Usually, adjust the secondary side delay phase δ and the inter-bridge phase shift

The size and direction of the power flow required by the system can be achieved. Therefore, based on the phase-shift control, the phase-shift variables from the primary and secondary side controllers (

and δ) are converted into the switching signals of the converter switches S1-S8, which effectively adjust the amplitude and phase of the primary and secondary side converter voltages to achieve the power flow required by the BCPT system.

然后根据系统的实际输出功率与期望的功率进行比较，调整副边变换器延迟相位δ和桥间相移

以满足系统实际功率需求。此时，功率流流向和大小已经和期望功率流相同，系统工作结束。其具体步骤如下：The flow chart of the power flow control method of the BCPT system proposed by the present invention is shown in FIG. 7 . At the start of the system, the primary and secondary devices are connected wirelessly to initialize the switching frequency, primary converter output voltage and desired power flow settings. First adjust the phase shift between primary bridges according to the desired primary converter output voltage _Vp

Then, according to the comparison between the actual output power of the system and the expected power, the delay phase δ and the inter-bridge phase shift of the secondary converter are adjusted.

to meet the actual power requirements of the system. At this point, the power flow direction and size are the same as the expected power flow, and the system work is over. The specific steps are as follows:

S1. The primary side converter and the secondary side converter are connected by wireless communication, and the switching frequency, the output voltage and expected power of the primary side converter are initialized at the same time;

得到期望的原边变换器输出电压V_p；S2. Adjust the primary side converter to generate a phase shift between bridges

Obtain the desired primary-side converter output voltage V _p ;

S3. Obtain the actual output power P of the system, and determine whether the actual output power P of the system is greater than the set power;

以满足系统实际功率需求；S4. If the actual output power P of the system is equal to the set power, adjust the secondary side converter to generate the delay phase δ and the inter-bridge phase shift

To meet the actual power requirements of the system;

S5. If the actual output power P of the system is equal to the set power, wait for the power to reach a steady state, and the final desired power is equal to the actual output power.

The two-way electric field coupled wireless power transmission system based on the double-sided LC resonant network proposed by the present invention is suitable for the two-way power transmission between the power grid and the application of electric vehicles and multiple electronic equipments, so that the power between the electric vehicles or the electric equipment can be transmitted. The magnitude and direction of the flow can be adjusted and controlled by the phase or amplitude of the voltage generated by the primary and secondary converters. The proposed control method can be effectively applied to the power flow regulation of the BCPT system.

It should be noted that, herein, the terms "comprising", "comprising" or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, apparatus, article or method comprising a series of elements includes not only those elements, It also includes other elements not expressly listed or inherent to such a process, apparatus, article or method. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, apparatus, article, or method that includes the element.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied to other related All technical fields are similarly included in the scope of patent protection of the present invention.

Claims (10)

1. The bidirectional electric field coupling type wireless electric energy transmission system comprises a primary circuit and a secondary circuit, and is characterized in that the primary circuit comprises a primary power interface, a primary converter, a primary resonant network and a pair of primary metal plates, the secondary circuit comprises a secondary power interface, a secondary converter, a secondary resonant network and a pair of secondary metal plates, a primary controller is connected to the primary converter, a secondary controller is connected to the secondary converter, and the primary circuit and the secondary circuit are connected through the pair of primary metal platesTwo-way electric field coupling formula wireless power transmission is realized to polar plate and a pair of secondary side metal polar plate, wherein: the primary side controller controls the primary side converter to generate inter-bridge phase shift

The secondary side controller controls the secondary side converter to generate a delay phase delta and an inter-bridge phase shift

The relative phase angle of the primary and secondary output voltages is theta when the angle is 0 DEG<θ<When the angle is 180 degrees, the forward power transmission of the system is realized, and when the angle is-180 degrees<θ<And when the angle is 0 degrees, the reverse power transmission of the system is realized.

2. The two-way electric field coupled wireless power transfer system of claim 1, wherein: a primary side filter capacitor C is arranged between the primary side power interface and the primary side converter _d A secondary filter capacitor C is arranged between the secondary power interface and the secondary converter _o 。

3. The two-way electric field coupled wireless power transfer system of claim 1 or 2, wherein: the primary side resonance network and the secondary side resonance network both adopt LC resonance networks, wherein: the primary side resonant network comprises a primary side resonant inductor L ₁ And primary side compensation capacitor C _f1 The secondary resonant network comprises a secondary resonant inductor L ₂ And secondary side compensation capacitor C _f2 。

4. The two-way electric field coupled wireless power transfer system of claim 3, wherein: the parameters of each electric appliance element in the primary side resonant network and the secondary side resonant network meet the following conditions:

where ω is the angular frequency of system operation, L ₁ Is a primary side resonance inductor L ₁ Self-inductance of (L) ₂ Is a secondary side resonance inductor L ₂ Self-induction of (C) ₁ Is the equivalent self-capacitance, C, of the primary side resonant circuit in the equivalent current source model of the system ₂ Is the equivalent self-capacitance, C, of the secondary side resonant circuit in the equivalent current source model of the system _M And the equivalent mutual capacitance of the electric field coupling mechanism formed by the pair of primary side metal polar plates and the pair of secondary side metal polar plates.

5. The two-way electric field coupled wireless power transfer system of claim 4, wherein: the primary side resonant circuit equivalent self-capacitance C ₁ ＝C _in1 +C _f1 The secondary resonant circuit is equivalent to a self-capacitance C ₂ ＝C _in2 +C _f2 The equivalent mutual capacitance of the electric field coupling mechanism

Wherein:

C _f1 compensating the capacitance C for the primary side _f1 Capacitance value of C _f2 Compensating the capacitance C for the secondary side _f2 The capacitance value of (a);

intermediate variables

Intermediate variables

The pair of primary metal plates comprises a plate P ₁ And a polar plate P ₂ The pair of secondary metal polar plates comprises a polar plate P ₃ And a polar plate P ₄ And then:

C ₁₂ indicating polar plate P ₁ And a polar plate P ₂ Equivalent capacitance between, C ₁₃ Indicating polar plate P ₁ And a polar plate P ₃ Equivalent capacitance between, C ₁₄ Indicating polar plate P ₁ And a polar plate P ₄ Equivalent capacitance between, C ₂₃ Representing a polar plate P ₂ And a polar plate P ₃ Equivalent capacitance therebetween, C ₂₄ Representing a polar plate P ₂ And a polar plate P ₄ Equivalent capacitance therebetween, C ₃₄ Representing a polar plate P ₃ And a polar plate P ₄ The equivalent capacitance therebetween.

6. The two-way electric field coupled wireless power transfer system of claim 1, 4 or 5, wherein: the primary side converter and the secondary side converter both adopt full-bridge reversible rectifiers, wherein the primary side converter comprises a switch tube S1, a switch tube S2, a switch tube S3 and a switch tube S4, and the secondary side converter comprises a switch tube S5, a switch tube S6, a switch tube S7 and a switch tube S8.

7. The two-way electric field coupled wireless power transfer system of claim 4 or 5, wherein: the primary side controller and the secondary side controller are used for controlling the primary side controller and the secondary side controller according to the active power P received by the secondary side converter _r And reactive power Q _r According to the following requirements:

controlling said primary converter and said secondary converter in a constrained relationship of, wherein V _d Representing the DC voltage, V, of the primary power supply interface _o And indicating the direct-current voltage of the secondary power interface.

8. The two-way electric field coupled wireless power transfer system of claim 1, wherein: the primary side controller and the secondary side controller control the primary side converter and the secondary side converter to realize maximum forward power transmission or reverse power transmission according to a mode that theta is +/-90 degrees.

9. The two-way electric field coupled wireless power transfer system of claim 1 or 8, wherein: the primary and secondary circuits have outputs connected to the electronic device and absorb or transfer power, and the output interfaces at both ends are represented by dc power supplies. When the system transmits forward power, the primary side direct current power supply outputs energy, and the secondary side power supply receives energy; when the system is in reverse power transmission, the secondary side power supply outputs energy, and the primary side power supply receives energy.

10. A control method for the two-way electric field coupled wireless power transfer system of any one of claims 1 to 9, comprising the steps of:

s1, the primary side converter and the secondary side converter are in wireless communication connection, and meanwhile, the switching frequency, the output voltage of the primary side converter and the expected power are initialized;

s2, adjusting the primary side converter to generate the phase shift between the bridges

Obtaining a desired output voltage V of the primary converter _p ；

S3, obtaining the actual output power P of the system, and judging whether the actual output power P of the system is larger than the set power;

s4, if the actual output power P of the system is not equal to the set power, adjusting the secondary side converter to generate the delay phase delta and the phase shift between bridges

To meet the actual power requirements of the system;

and S5, if the actual output power P of the system is equal to the set power, waiting for the power to reach a steady state, and finally, enabling the expected power to be equal to the actual output power.

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