Induction power bidirectional transmission system based on lcc-s type compensation and control method thereof

Abstract

The present application relates to wireless power transmission technical field, especially to a kind of based on LCC-S type compensation's inductive power two-way transmission system and control method thereof.The system includes primary side module and secondary side module, primary side module includes primary side DC power supply, primary side converter, primary side compensation network and primary side coil, secondary side module includes secondary side coil, secondary side compensation network, secondary side converter and secondary side DC power supply, primary side DC power supply, primary side converter, primary side compensation network, primary side coil are sequentially connected, secondary side coil, secondary side compensation network, secondary side converter, secondary side DC power supply are sequentially connected, primary side coil and secondary side coil mutual inductance, primary side compensation network is LCC type compensation topology, and secondary side compensation network is S type compensation topology.The present application has the advantages of significantly improving maximum output power, can realize the wireless two-way transmission of energy, the control of electric energy flow direction and power size is simple, etc., is suitable for the V2G wireless charging system of electric vehicle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless power transmission technology, in particular to an inductive power bidirectional transmission system based on LCC-S compensation and a control method thereof. BACKGROUND

[0002] Wireless power transmission technology is a kind of technology that uses space medium as a carrier to transmit power without direct physical cable connection. Wireless power transmission technology is flexible, safe and not affected by different charging interfaces, so it has been widely researched at home and abroad.

[0003] The application scenario of bidirectional wireless power transmission system is very promising. It can provide energy for the receiving side load from the power transmitting side, and also can return the excess power stored in the receiving side load to the power transmitting side. When the electric vehicle as the receiving side load interacts with the power grid wirelessly, it can help the power grid to "peak shaving". SUMMARY

[0004] The present application provides an inductive power bidirectional transmission system based on LCC-S compensation and a control method thereof, aiming at the application of bidirectional wireless power transmission.

[0005] The present application provides an inductive power bidirectional transmission system based on LCC-S compensation, which comprises a primary side module and a secondary side module. The primary side module comprises a primary side DC power supply, a primary side converter, a primary side compensation network and a primary side coil. The secondary side module comprises a secondary side coil, a secondary side compensation network, a secondary side converter and a secondary side DC power supply. The primary side DC power supply, the primary side converter, the primary side compensation network and the primary side coil are connected in sequence. The secondary side coil, the secondary side compensation network, the secondary side converter and the secondary side DC power supply are connected in sequence. The primary side coil and the secondary side coil are mutually inductive. The primary side compensation network is an LCC compensation topology, and the secondary side compensation network is an S compensation topology.

[0006] The primary side converter is used to invert the DC voltage provided by the primary side DC voltage source into a square wave voltage, or to convert the AC voltage received by the primary side into a DC voltage. The secondary side converter is used to invert the DC voltage provided by the secondary side DC voltage source into a square wave voltage, or to convert the AC voltage received by the secondary side into a DC voltage.

[0007] The primary side coil is used to emit the energy output by the primary side converter to the secondary side coil, or to receive the energy emitted by the secondary side coil. The secondary side coil is used to emit the energy output by the secondary side converter to the primary side coil, or to receive the energy emitted by the primary side coil.

[0008] As a further improvement of the present application, the primary side converter and the secondary side converter are both composed of switching tubes to form bidirectional inverters or rectifiers, including but not limited to full-bridge converters and half-bridge converters.

[0009] As a further improvement of the present application, the switching tubes in the primary side converter and the secondary side converter are composed of power switching tubes, MOSFET tubes or IGBT tubes.

[0010] As a further improvement of the present application, the switching frequencies of the primary side converter and the secondary side converter are the same and equal to the resonant frequency of the compensation network.

[0011] As a further improvement of the present application, the primary side compensation network comprises a series compensation inductor L f , a parallel compensation capacitor C f and a primary side series compensation capacitor C p , one end of the series compensation inductor L f is connected to the positive output end of the primary side converter, the other end of the series compensation inductor L f , one end of the parallel compensation capacitor C f and one end of the primary side series compensation capacitor C p are connected together, the other end of the parallel compensation capacitor C f , the negative output end of the primary side converter and one end of the primary side coil L p are connected together, the other end of the primary side coil L p and the other end of the primary side series compensation capacitor C p are connected.

[0012] As a further improvement of the present application, the secondary side compensation network is composed of a secondary side series capacitor C s , one end of the secondary side series capacitor C s is connected to one end of the secondary side coil L s , the other end of the secondary side series capacitor C s is connected to the positive output end of the secondary side converter, and the other end of the secondary side coil L s is connected to the negative output end of the secondary side converter.

[0013] As a further improvement of the present application, the primary side DC power V in and the secondary side DC power V o are devices for generating DC voltage, including but not limited to batteries, electrolytic capacitors, the positive and negative poles of the primary side DC power V in are connected to the primary side converter respectively, and the positive and negative poles of the secondary side DC power V o are connected to the secondary side converter respectively.

[0014] The present application also provides an inductive power bidirectional transmission control method based on LCC-S type compensation, comprising the following steps:

[0015] S1. Control the output voltage v ABthe fundamental component v1 of the primary side transformer output voltage v CD the phase difference between the fundamental component v2 of the primary side transformer output voltage v

[0016] S2. Controlling the direction of power flow by controlling the magnitude relationship between V1M / L f and V2: when V1M / L f >V2, the power flow is transmitted from the primary side module to the secondary side module; when V1M / L f <V2, the power flow is transmitted from the secondary side module to the primary side module; wherein V1 is the amplitude of the fundamental component v1, V2 is the amplitude of the fundamental component v2, M is the mutual inductance between the primary side coil and the secondary side coil, and L f is the inductance of the series compensation inductance in the primary side compensation network.

[0017] As a further improvement of the application, the method further comprises the step of:

[0018] S3. When the magnitude relationship between V1M / L f and V2 is fixed, the magnitude of the transmitted power is changed by changing the amplitude V1 and the amplitude V2: when the power flow remains from the primary side module to the secondary side module, the power is increased by increasing the amplitude V1 or decreasing the amplitude V2, and the power is decreased by decreasing the amplitude V1 or increasing the amplitude V2; when the power flow remains from the secondary side module to the primary side module, the power is decreased by increasing the amplitude V1 or decreasing the amplitude V2, and the power is increased by decreasing the amplitude V1 or increasing the amplitude V2.

[0019] Wherein, the amplitude V1 and the amplitude V2 can be controlled separately, or the amplitude V1 and the amplitude V2 can be controlled simultaneously to adjust the magnitude of the power.

[0020] As a further improvement of the application, in the step S3, the way of changing the amplitude V1 and the amplitude V2 comprises:

[0021] S31. The primary side transformer and the secondary side transformer change the primary side transformer output voltage v AB and the secondary side transformer output voltage v CD by phase shift or variable duty cycle control;

[0022] S32. Directly adjusting the voltage value of the primary side DC power supply voltage V in or the secondary side DC power supply voltage V o .

[0023] The application has the advantages of significantly increasing the maximum output power, realizing wireless bidirectional energy transmission, controlling the power flow direction and the power magnitude simply, and being suitable for V2G wireless charging system of electric vehicles, compared with the traditional wireless power transmission system. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 This is a circuit structure diagram of a single-load bidirectional wireless power transmission system provided in an embodiment of the present invention;

[0025] Figure 2 This is the fundamental equivalent circuit diagram of the single-load bidirectional wireless power transmission system of the present invention;

[0026] Figure 3 In this invention Figure 2 The primary and secondary voltage and current waveforms when V1 = 130V and V2 = 100V;

[0027] Figure 4 In this invention Figure 2 The primary and secondary voltage and current waveforms when V1 = 125V and V2 = 100V;

[0028] Figure 5 In this invention Figure 2 The primary and secondary voltage and current waveforms when V1 = 125V and V2 = 90V. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Example 1:

[0031] like Figure 1 As shown, the present invention discloses a bidirectional inductive power transmission system based on LCC-S type compensation, comprising a primary-side module 1 and a secondary-side module 2. The primary-side module 1 includes a primary-side DC power supply 3, a primary-side converter 4, a primary-side compensation network 5, and a primary-side coil 6. The secondary-side module 2 includes a secondary-side coil 7, a secondary-side compensation network 8, a secondary-side converter 9, and a secondary-side DC power supply 10. The primary-side DC power supply 3, the primary-side converter 4, the primary-side compensation network 5, and the primary-side coil 6 are connected in sequence, and the secondary-side coil 7, the secondary-side compensation network 8, the secondary-side converter 9, and the secondary-side DC power supply 10 are connected in sequence. The primary-side coil 6 and the secondary-side coil 7 are mutually inductive. The primary-side compensation network 5 is an LCC type compensation topology, and the secondary-side compensation network 8 is an S type compensation topology.

[0032] Primary DC power supply V in and secondary DC power supply V o This includes any device capable of generating DC voltage, such as batteries and electrolytic capacitors. The power supply also further includes AC / DC converters or rectifiers, so it may have single-phase or multi-phase AC power (typically 50Hz or 60Hz).

[0033] The primary-side converter 4 is used to: invert the DC voltage provided by the primary-side DC power supply 3 into a square wave voltage, or convert the AC voltage received by the primary side into a DC voltage; the secondary-side converter 9 is used to: invert the DC voltage provided by the secondary-side DC power supply 10 into a square wave voltage, or convert the AC voltage received by the secondary side into a DC voltage.

[0034] Primary coil L p Used to: transmit the energy output from the primary-side converter 4 to the secondary-side coil L s Or receive secondary coil L s Energy emitted; secondary coil L s Used to: transmit the energy output from the secondary converter 9 to the primary coil L p Or receive the primary coil L p The energy emitted.

[0035] Both the primary-side converter 4 and the secondary-side converter 9 are composed of several power switches, and their structures are not unique; they are bidirectional inverters / rectifiers, including full-bridge converters and half-bridge converters. When energy is transferred from the primary side to the secondary side, the primary-side converter 4 operates as an inverter, converting the primary-side DC voltage to a square wave voltage, while the secondary-side converter 9 operates as a rectifier, converting the secondary-side AC voltage to DC voltage. Conversely, when energy is transferred from the secondary side to the primary side, the secondary-side converter 9 operates as an inverter, converting the secondary-side DC voltage to a square wave voltage, while the primary-side converter 4 operates as a rectifier, converting the primary-side AC voltage to DC voltage.

[0036] The switching transistors in the primary-side converter 4 and the secondary-side converter 9 are composed of power switching transistors MOSFETs or IGBTs.

[0037] The primary-side converter 4 and the secondary-side converter 9 have the same switching frequency, which is equal to the resonant frequency of the compensation network. The voltage difference between the port connecting the primary-side converter 4 and the primary-side compensation topology is called the primary-side converter output voltage V. AB The voltage difference between the ports of the secondary-side converter 9 and the secondary-side compensation topology is called the secondary-side converter output voltage V. CD v AB and v CD The frequency is the same as the resonant frequency of the compensation network.

[0038] The primary-side compensation network 5 includes a series compensation inductor L. f Parallel compensation capacitor C f The primary-side series compensation capacitor C p The positive output terminal of the primary-side converter 4 is connected to the series compensation inductor L. f One end is connected to a series compensation inductor L f The other end, parallel compensation capacitor C f One end, primary side series compensation capacitor Cp One end of each capacitor is connected together, and a parallel compensation capacitor C is connected. f The other end, the negative output terminal of the primary-side converter 4, and the primary-side coil L p One end of the primary coil L is connected together. p The other end is connected in series with the primary side by a compensation capacitor C. p The other end is connected.

[0039] The secondary-side compensation network 8 consists of a secondary-side series capacitor C. s Composition, secondary side series capacitor C s One end is connected to the secondary coil L s One end is connected, and a capacitor C is connected in series on the secondary side. s The other end is connected to the positive output terminal of the secondary converter 9, and the secondary coil L s The other end is connected to the negative output terminal of the secondary converter 9.

[0040] Example 2:

[0041] The present invention provides a control method for a bidirectional inductive power transmission system based on LCC-S type compensation, comprising the following steps:

[0042] S1. Controls the output voltage v of the primary-side converter. AB The fundamental component v1 and the secondary converter output voltage v CD The phase difference between the fundamental components v2 is 0.

[0043] The output voltage of the primary or secondary converter is defined as: the port where the converter is connected to the compensation topology, including the "+" output terminal and the "-" output terminal. AB and v CD The fundamental components are denoted as v1 and v2, respectively. The amplitudes of v1 and v2 are denoted as V1 and V2, respectively, and their frequencies are equal to the resonant frequency of the compensation network, denoted as ω. s =2πf s .

[0044] Analysis using the fundamental equivalent method and the T-type equivalent circuit shows that the reactive power of the system is zero when v1 and v2 are in phase. In practice, a very small phase difference between v1 and v2 can also be used.

[0045] S2. By controlling V1M / L f The relationship between V1 and V2 is used to control the direction of power flow: when V1M / L f When V > V2, energy is transferred from the primary-side module to the secondary-side module; when V1M / L f When V1 < V2, energy is transferred from the secondary module to the primary module; where V1 is the amplitude of the fundamental component v1, V2 is the amplitude of the fundamental component v2, M is the mutual inductance potential between the primary and secondary coils, and L... fV1M / L represents the inductance of the series compensation inductor in the primary-side compensation network. f It is derived from an ideal formula, but in reality, there may be a small deviation.

[0046] S3.V1M / L f When the magnitude relationship between amplitudes V1 and V2 is fixed, the magnitude of the transmitted power is changed by altering the amplitudes V1 and V2: when the power flow remains from the primary module to the secondary module, increasing the amplitude V1 or decreasing the amplitude V2 increases the power, and decreasing the amplitude V1 or increasing the amplitude V2 decreases the power; when the power flow remains from the secondary module to the primary module, increasing the amplitude V1 or decreasing the amplitude V2 decreases the power, and decreasing the amplitude V1 or increasing the amplitude V2 increases the power. The magnitude of the power can be adjusted by controlling the amplitudes V1 and V2 individually or simultaneously.

[0047] The methods for changing the amplitudes of v1 and v2 include, but are not limited to: 1. Using phase-shifting or variable duty cycle control in the primary and secondary converters to change v1 and v2 amplitudes. AB and v CD 1. Voltage pulse width; 2. Direct adjustment of V in or V o voltage (V) o =V out ).

[0048] The parameters of the compensation network are configured as follows:

[0049]

[0050]

[0051]

[0052] v AB and v CD The fundamental components are denoted as v1 and v2, respectively. v1 and v2 are frequencies ω. s =2πf s The sinusoidal voltage. A T-type equivalent circuit model is used. Figure 1 The system's fundamental frequency approximate equivalent circuit is as follows: Figure 2 As shown. Where, L rp and L rs These represent the leakage inductance of the primary and secondary windings, respectively, and M represents the mutual inductance between the primary and secondary windings. The leakage inductance and mutual inductance are related as follows: L rp +M=L p L rs +M=L s For ease of analysis, X A X B X CX D and X E Let X represent the equivalent impedance of each branch in the model, where Xi is the equivalent impedance of each branch. A =jωL f X B =1 / (jωC) f ), X C =jωL rp +1 / (jωC p ), X D =jωM,X E =jωL rs +1 / (jωC s i1 to i5 represent the currents in each branch. According to Kirchhoff's voltage and current laws, we have:

[0053]

[0054] X0 = X A X B X D +X A X B X E +X A X C X D +X A X C X E +X B X C X D +X B X C X E +X A X D X E +X B X D X E

[0055] Based on the parameter configuration, the expressions for i1 and i3 can be simplified.

[0056]

[0057]

[0058] The expressions for the active and reactive power on the primary side are:

[0059]

[0060]

[0061] The expressions for active and reactive power on the secondary side are:

[0062]

[0063]

[0064] Among them, i1 * i2 is the conjugate of the inlet current of the primary-side LCC resonant cavity. * To compensate for the current in the secondary side inductor, θ is the phase difference between v1 and v2, R p For the primary side coil L p The internal resistance, R f To compensate for inductance L f The internal resistance is given by V1 and V2, which are the amplitudes of v1 and v2, respectively.

[0065] Therefore, when θ = 0, Q1 = Q2 = 0. Under the premise that θ = 0, when V1M / L f When V1 > V2, P1 > 0, P2 < 0, and energy is transferred from the primary side to the secondary side. When V1 = M / L f When V2 < 0, P1 < 0, P2 > 0, and energy is transferred from the secondary side to the primary side.

[0066] Furthermore, V1M / L f When the relationship between V1 and V2 is fixed, the power can be changed by altering V1 and V2. Specifically, when the power flow remains from the primary to the secondary side, increasing V1 or decreasing V2 increases the power, and decreasing V1 or increasing V2 decreases the power. Conversely, when the power flow remains from the secondary to the primary side, increasing V1 or decreasing V2 decreases the power, and decreasing V1 or increasing V2 increases the power. The power can be adjusted by controlling V1 and V2 individually or simultaneously.

[0067] According to the power expression of energy transmission in the LCC-S type bidirectional wireless power transmission system, under the premise of keeping θ=0, the control circuit changes the direction and magnitude of power flow by changing the magnitude of v1 or v2.

[0068] The feasibility of the control strategy for the LCC-S type bidirectional wireless power transfer system is demonstrated through simulation, with the switching frequency set to 85 kHz. p =L s =121μH, M=29.0μH, L f =36.5μH, C f =96.0 nF, C p =41.9 nF, Cs=29.0 nF, R p =0.2Ω, R f =0.05Ω, secondary side coil L s internal resistance R s =0.2Ω. Simulation results are as follows:Figure 3 and Figure 4 As shown. Figure 3 In the equation, V1 = 130V and V2 = 100V, and energy is transferred from the primary side to the secondary side. Figure 4 In the equation, V1 = 125V and V2 = 100V, and energy is transferred from the secondary side to the primary side. Figure 5 In the equation, V1 = 125V and V2 = 90V, energy is transferred from the primary side to the secondary side.

[0069] Simulations reveal the advantages of this structure: 1. It has a very wide output power adjustment range; 2. The power flow direction or magnitude can be controlled by changing one or both of the amplitudes of v1 and v2; 3. The control method for changing the power flow direction is simple.

[0070] The methods for changing the amplitudes of v1 and v2 include, but are not limited to: 1. Using phase-shifting or variable duty cycle control in the primary and secondary converters to change v1 and v2 amplitudes. AB and v CD 1. Voltage pulse width; 2. Direct adjustment of V in or V o The voltage.

[0071] Bidirectional power flow is important in many applications. One example is electric vehicles, where excess energy may be stored in the car's battery, and if the car is not in use, this energy may be returned to the power grid during peak usage times.

[0072] This invention is used to realize bidirectional power transfer, but it is not limited to this application and can also be used to realize unidirectional power transmission.

[0073] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A bidirectional inductive power transmission system based on LCC-S type compensation, characterized in that, The system includes a primary-side module and a secondary-side module. The primary-side module includes a primary-side DC power supply, a primary-side converter, a primary-side compensation network, and a primary-side coil. The secondary-side module includes a secondary-side coil, a secondary-side compensation network, a secondary-side converter, and a secondary-side DC power supply. The primary-side DC power supply, primary-side converter, primary-side compensation network, and primary-side coil are connected in sequence. The secondary-side coil, secondary-side compensation network, secondary-side converter, and secondary-side DC power supply are also connected in sequence. The primary-side coil and secondary-side coil are mutually inductant. The primary-side compensation network is an LCC-type compensation topology, and the secondary-side compensation network is an S-type compensation topology. The primary-side converter is used to: invert the DC voltage provided by the primary-side DC power supply into a square wave voltage, or convert the AC voltage received by the primary side into a DC voltage; the secondary-side converter is used to: invert the DC voltage provided by the secondary-side DC power supply into a square wave voltage, or convert the AC voltage received by the secondary side into a DC voltage. The primary coil is used to: transmit the energy output by the primary converter to the secondary coil, or receive the energy emitted by the secondary coil; the secondary coil is used to: transmit the energy output by the secondary converter to the primary coil, or receive the energy emitted by the primary coil. The control method for the bidirectional inductive power transmission system based on LCC-S type compensation includes the following steps: S1. Control the output voltage of the primary-side converter v AB fundamental component of v 1 and secondary converter output voltage v CD fundamental component of v The phase difference between the two is 0; S2. By controlling and V The magnitude of 2 is used to control the direction of power flow: when At that time, energy is transferred from the primary side module to the secondary side module; when At that time, energy is transferred from the secondary side module to the primary side module; among which, V 1 represents the fundamental frequency component. v The amplitude of 1, V 2 represents the fundamental frequency component. v The amplitude of 2, M This represents the mutual inductance potential between the primary and secondary coils. L f This represents the inductance of the series compensation inductor in the primary-side compensation network.

2. The bidirectional inductive power transmission system based on LCC-S type compensation according to claim 1, characterized in that, Both the primary-side converter and the secondary-side converter are bidirectional inverters or rectifiers composed of switching transistors, including but not limited to full-bridge converters and half-bridge converters.

3. The bidirectional inductive power transmission system based on LCC-S type compensation according to claim 2, characterized in that, The switching transistors in the primary-side converter and the secondary-side converter are composed of power switching transistors, MOSFETs, or IGBTs.

4. The bidirectional inductive power transmission system based on LCC-S type compensation according to claim 1, characterized in that, The switching frequencies of the primary-side converter and the secondary-side converter are the same and equal to the resonant frequency of the compensation network.

5. The bidirectional inductive power transmission system based on LCC-S type compensation according to claim 1, characterized in that, The primary-side compensation network includes a series compensation inductor. L f Parallel compensation capacitors C f series compensation capacitor with primary side C p The positive output terminal of the primary-side converter is connected to a series compensation inductor. L f One end is connected to the series compensation inductor. L f The other end, parallel compensation capacitor C f One end, primary side series compensation capacitor C p One end of the parallel compensation capacitor is connected together. C f The other end, the negative output terminal of the primary-side converter, the primary-side coil L p One end of the primary coil is connected together. L p The other end is connected in series with the primary side by a compensation capacitor. C p The other end is connected.

6. The bidirectional inductive power transmission system based on LCC-S type compensation according to claim 1, characterized in that, The secondary-side compensation network consists of a secondary-side series capacitor. C s The secondary-side series capacitor is configured as follows: C s One end and the secondary coil L s One end is connected, and the secondary side is connected in series with a capacitor. C s The other end is connected to the positive output terminal of the secondary-side converter, and the secondary-side coil L s The other end is connected to the negative output terminal of the secondary converter.

7. The bidirectional inductive power transmission system based on LCC-S type compensation according to claim 1, characterized in that, The primary DC power supply V in and secondary DC power supply V o Devices that generate DC voltage, including but not limited to batteries and electrolytic capacitors, the primary-side DC power supply V in The positive and negative terminals are respectively connected to the primary-side converter, and the secondary-side DC power supply V o The positive and negative terminals are connected to the secondary converter, respectively.

8. The bidirectional inductive power transmission system based on LCC-S type compensation according to claim 1, characterized in that, It also includes the following steps: S3. and V When the magnitude relationship of 2 is fixed, by changing the amplitude V 1 and amplitude V 2. To change the magnitude of the transmitted power: When the power flow remains from the primary module to the secondary module, the magnitude is increased. V 1 or reduce the amplitude V 2. To increase power, reduce amplitude. V 1 or increase in value V 2. To reduce power; when the power flow remains from the secondary module to the primary module, the magnitude is increased. V 1 or reduce the amplitude V 2. To reduce power, by reducing the amplitude. V 1 or increase in value V 2. To increase power; among which, the amplitude is controlled separately. V 1 and amplitude V 2. Change, or simultaneously control the amplitude V 1 and amplitude V 2. Adjust the power level by changing the parameters.

9. The bidirectional inductive power transmission system based on LCC-S type compensation according to claim 8, characterized in that, In step S3, the amplitude is changed. V 1 and amplitude V Method 2 includes: S31. The primary-side converter and the secondary-side converter are controlled by phase shifting or changing the duty cycle to change the output voltage of the primary-side converter. v AB and secondary converter output voltage v CD Voltage pulse width; S32. Directly adjust the primary DC power supply voltage. V in or secondary DC power supply voltage V o The voltage value.

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