CN116780788A - Wireless charging system based on LCC-S compensation topological junction and control method thereof - Google Patents
Wireless charging system based on LCC-S compensation topological junction and control method thereof Download PDFInfo
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Abstract
The invention discloses a wireless charging system based on LCC-S compensation topological junction and a control method thereof, and relates to the field of wireless charging.
Description
Technical Field
The invention relates to the field of wireless charging, in particular to a wireless charging system based on an LCC-S compensation topological junction and a control method thereof.
Background
The magnetic field coupling type wireless charging system comprises a primary side energy conversion mechanism consisting of rectification and high-frequency inversion, an energy transmission mechanism consisting of a primary/secondary side compensation network and a magnetic coupler, and a secondary side energy pickup mechanism consisting of a rectifier bridge and a load. The power frequency alternating voltage of the power grid is converted into intermediate-stage direct voltage through an AC/DC rectifier in the primary energy conversion mechanism; the high-frequency inverter after the rectifier inverts the intermediate-level direct current to generate high-frequency alternating current and the high-frequency alternating current is injected into the magnetic coupler, and the primary compensation network and the primary coil form a resonance network; under the influence of an alternating magnetic field, a receiving coil above the transmitting coil induces high-frequency alternating voltage, and resonates with a secondary compensation network to transfer energy to a load through a high-frequency rectifier bridge.
The wireless charging (WirelessPowerTransfer, WPT) technology has been attracting more attention in recent years due to the advantages of convenience, safety and the like, and is widely applied to biomedical implants, consumer electronic products, underwater loads, electric automobiles and the like. The WPT uses a magnetic field as a transmission medium to realize the transfer of energy from a transmitting end to a receiving end, thereby avoiding direct physical contact. However, deviations in the relative positions of the transmitting and receiving ends can affect the magnetic field distribution and thereby alter the power transfer stability of the system. Therefore, in the actual transmission process, it is necessary to improve the output stability of the WPT system in the case of offset. At present, the anti-offset capability of the system output is improved mainly by improving system parameters and developing a control strategy. System parameter improvement refers to reducing the output fluctuation of the system through the relation of element parameters, but parameter improvement can only reduce the output fluctuation of the system, so that a wide range of output stability is often required to be realized by combining a control strategy. The control strategy means that the power is stabilized by adjusting controllable devices at the transmitting end or the receiving end. The WPT system control strategy in the present stage needs to be implemented through communication between the receiving end and the transmitting end, and this mode is affected by electromagnetic interference generated by wireless charging, and communication delay also affects system stability.
Disclosure of Invention
The invention aims to provide a wireless charging system based on an LCC-S compensation topological structure and a control method thereof, which can ensure that the output of a receiving side is stable when coupling fluctuates in a wide range, and improve the stability of the output of a WPT system under the relative position deviation between a transmitting end and a receiving end.
In order to achieve the above object, the present invention provides the following solutions:
the wireless charging system comprises a transmitting side full-bridge inverter, a receiving side half-control rectifier bridge, a secondary resonance compensation network series capacitor module, an inductor of a primary side resonance compensation network, a parallel capacitor of the primary side resonance compensation network, a series capacitor of the primary side resonance compensation network, a transmitting coil and a receiving coil;
one end of the output end of the transmitting side full-bridge inverter is connected with one end of an inductor of the primary side resonance compensation network; the other end of the inductor of the primary side resonance compensation network is respectively connected with one end of the parallel capacitor of the primary side resonance compensation network and one end of the series capacitor of the primary side resonance compensation network; the other end of the series capacitor of the primary side resonance compensation network is connected with one end of the transmitting coil; the other end of the transmitting coil is respectively connected with the other end of the parallel capacitor of the primary side resonance compensation network and the other end of the output end of the transmitting side full-bridge inverter;
the transmitting coil is coupled with the receiving coil; one end of the receiving coil is connected with the input end of the secondary resonance compensation network series capacitor module; the other end of the receiving coil is connected with one end of the input end of the receiving side half-control rectifier bridge; the output end of the secondary resonance compensation network series capacitor module is connected with the other end of the input end of the receiving side half-control rectifier bridge;
the secondary resonance compensation network series capacitance module comprises a first MOSFET, a second MOSFET, a parallel capacitance of the secondary resonance compensation network and a series capacitance of the secondary resonance compensation network; the source electrode of the first MOSFET is connected with one end of the receiving coil; the drain electrode of the first MOSFET is connected with the drain electrode of the second MOSFET; the source electrode of the second MOSFET is connected with one end of the series capacitor of the secondary resonance compensation network; the other end of the series capacitor of the secondary resonance compensation network is connected with the other end of the input end of the receiving side half-control rectifier bridge; one end of a parallel capacitor of the secondary resonance compensation network is connected with one end of the receiving coil; the other end of the parallel capacitor of the secondary resonance compensation network is connected with the source electrode of the second MOSFET.
Optionally, the receiving side half-controlled rectifier bridge includes a first rectifier diode, a second rectifier diode, a receiving side first MOSFET and a receiving side second MOSFET;
the other end of the series capacitor of the secondary resonance compensation network is respectively connected with the anode of the first rectifying diode and the drain electrode of the receiving side first MOSFET; the cathode of the first rectifying diode is connected with the cathode of the second rectifying diode and one end of the load respectively; the source electrode of the first MOSFET at the receiving side is respectively connected with the source electrode of the second MOSFET at the receiving side and the other end of the load; the other end of the receiving coil is connected with the anode of the second rectifying diode and the drain electrode of the second MOSFET at the receiving side respectively.
Optionally, the wireless charging system further comprises a filter capacitor; the filter capacitor is respectively connected with one end of the load and the other end of the load.
Optionally, the transmitting-side full-bridge inverter includes a transmitting-side first MOSFET, a transmitting-side second MOSFET, a transmitting-side third MOSFET, a transmitting-side fourth MOSFET, and a power supply;
the positive electrode of the power supply is respectively connected with the drain electrode of the first MOSFET at the transmitting side and the drain electrode of the third MOSFET at the transmitting side; the negative electrode of the power supply is respectively connected with the source electrode of the second MOSFET at the transmitting side and the source electrode of the fourth MOSFET at the transmitting side; one end of an inductor of the primary side resonance compensation network is connected with a source electrode of the transmitting side first MOSFET and a drain electrode of the transmitting side second MOSFET respectively; the other end of the transmitting coil is connected with the source electrode of the transmitting side third MOSFET and the drain electrode of the transmitting side fourth MOSFET respectively.
A control method of a wireless charging system based on an LCC-S compensation topological junction is applied to the wireless charging system based on the LCC-S compensation topological junction, and comprises the following steps:
acquiring charging voltage and charging current at two ends of a load and preset direct-current output voltage of a receiving side half-control rectifier bridge;
obtaining voltage gain according to the charging voltage and the preset direct current output voltage;
calculating element parameters of the wireless charging system based on the LCC-S compensation topological junction according to the voltage gain and the topological structure of the wireless charging system based on the LCC-S compensation topological junction; the element parameters comprise the moving angle of the half-controlled rectifier bridge, the output resistance and the capacitance of the secondary resonance compensation network series capacitance module;
determining a variable capacitance parameter according to the element parameter; the variable capacitance parameters comprise a parallel capacitance of the secondary resonance compensation network and a series capacitance of the secondary resonance compensation network;
determining the switching voltage at two ends of a parallel capacitor of the secondary resonance compensation network according to the variable capacitance parameter;
judging whether the switching voltage meets the withstand voltage requirement according to the condition;
when the switching voltage does not meet the withstand voltage requirement, updating the coupling coefficient of the wireless charging system based on the LCC-S compensation topological junction, the inductance of the transmitting coil and the inductance of the receiving coil, and returning to the execution step of calculating element parameters of the wireless charging system based on the LCC-S compensation topological junction according to the voltage gain and the topological structure of the wireless charging system based on the LCC-S compensation topological junction;
and when the switching voltage does not meet the withstand voltage requirement, obtaining the wireless charging system with constant voltage output based on the LCC-S compensation topological junction.
Optionally, the calculating the element parameters of the wireless charging system based on the LCC-S compensation topological junction according to the voltage gain and the topology structure of the wireless charging system based on the LCC-S compensation topological junction specifically includes:
obtaining a moving angle of the half-control rectifier bridge according to the calculation formula of the voltage gain and the charging voltage; the calculation formula of the charging voltage is as follows:
wherein ,V0 For charging voltage, M is the coupling coefficient of a coupling transformer consisting of a receiving coil and a transmitting coil, V AB For the output voltage of the full-bridge inverter on the transmitting side, L f1 The inductance of the primary side resonance compensation network is adopted, and beta is the moving angle of the half-control rectifier bridge;
generating PWM control signals of a first MOSFET at the receiving side and a second MOSFET at the receiving side according to the moving angle;
determining an output resistance according to the charging voltage and the charging current;
according to the moving angle and the output resistance, a calculation formula of the capacitance of the secondary resonance compensation network series capacitance module is applied to determine the capacitance of the secondary resonance compensation network series capacitance module; the calculation formula of the capacitance of the secondary resonance compensation network series capacitance module is as follows:
wherein ,C2 The capacitance of the capacitor module is connected in series with the compensation network for the secondary resonance, L 2 For receiving inductance of coil, R 0 Beta is the moving angle of the half-control rectifier bridge, and omega is the working frequency.
Optionally, determining the variable capacitance parameter according to the element parameter specifically includes:
according to the capacitance of the secondary resonance compensation network series capacitance module, a calculation formula of the parallel capacitance of the secondary resonance compensation network and a calculation formula of the series capacitance of the secondary resonance compensation network are applied, and the parallel capacitance of the secondary resonance compensation network and the series capacitance of the secondary resonance compensation network are calculated; wherein,C x parallel capacitor of secondary resonance compensation network, C y Series capacitance of secondary resonance compensation network, C 2max Is C 2 Maximum value of C 2min Is C 2 Minimum value->Is thatAt->0.8π]Maximum value of>Is->At->Is set to be a minimum value of (c),
optionally, determining the switching voltage across the parallel capacitor of the secondary resonance compensation network according to the variable capacitance parameter specifically includes:
applying a calculation formula of the switching voltages at two ends of the parallel capacitor of the secondary resonance compensation network, and determining the switching voltages at two ends of the parallel capacitor of the secondary resonance compensation network according to the variable capacitance parameter;
the calculation formula of the switching voltage at two ends of the parallel capacitor of the secondary resonance compensation network is as follows:
B＝(ω 2 L 2 C x -C x /C y +0.053)/0.515
A＝3.023；
wherein ,Cx Parallel capacitor of secondary resonance compensation network, C y Series capacitance of secondary resonance compensation network, R 0 For output resistance, V AB For the output voltage of the full bridge inverter at the transmitting side, ω is the operating frequency, M is the coupling coefficient of a coupling transformer consisting of a receiving coil and a transmitting coil, L f1 Inductance of the primary side resonance compensation network, L 2 For receiving inductance of coil, M max Is the maximum value of the coupling coefficient.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a wireless charging system based on LCC-S compensation topological junction. Firstly, according to the topological structure of an inductive coupling type wireless power transmission system, the system parameter relation for enabling the inductive coupling type wireless power transmission system to realize a zero phase angle state in a constant voltage mode can be determined, so that the variable capacitance element parameter calculation value of the receiving side of the inductive coupling type wireless power transmission system is calculated; according to the element parameter calculation value, calculating and judging whether the variable capacitance peak voltage and current are smaller than the set highest peak voltage and current, if the voltage and current requirements are met, completing the system design, if the voltage and current requirements are not met, readjusting the coupler parameters to obtain the component parameters of the wireless charging system based on the LCC-S compensation topological junction, thereby obtaining the actual wireless charging system based on the LCC-S compensation topological junction, realizing the automatic control of the output voltage of the receiving side based on the LCC-S compensation topological junction under the offset condition, ensuring the single-side control of the WPT system under the wide-range coupling fluctuation, ensuring the stable output of the receiving side under the wide-range coupling fluctuation, and improving the stability of the output of the WPT system under the relative position deviation between the transmitting end and the receiving end.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of a wireless charging system based on LCC-S compensation topology according to the present invention;
FIG. 2 is a timing and waveform diagram of a half-controlled rectifier bridge;
FIG. 3 is a timing and waveform diagram of a switched capacitor according to the present invention;
FIG. 4 is a schematic diagram of the inverter output voltage and output current waveforms at steady state;
FIG. 5 is a schematic diagram of a control strategy of a receiving end according to the present invention;
FIG. 6 is a graph of g (M);
FIG. 7 is a flow chart of the system parameter design of the present invention;
FIG. 8 is C 2 Initial value adjustment flow chart.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a wireless charging system based on an LCC-S compensation topological structure and a control method thereof, which can ensure that the output of a receiving side is stable when coupling fluctuates in a wide range, and improve the stability of the output of a WPT system under the relative position deviation between a transmitting end and a receiving end.
The invention is suitable for a method of combining a variable capacitor (Switch controlledcapacitor, SCC) with a Semi-active rectifier bridge (SAR) at a receiving end of LCC-S topology, aims at the defect of realizing output characteristic control under deflection of a WPT system at the current stage, avoids wireless communication intervention control while guaranteeing a constant voltage output mode of the receiving end, and realizes independent control of the receiving side to realize output stability when wide-range coupling fluctuation.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Example 1
As shown in fig. 1, the present invention provides a wireless charging system based on LCC-S compensation topology, the wireless charging system includes a transmitting side full bridge inverter, a receiving side half-controlled rectifier bridge, a secondary resonance compensation network series capacitance module, an inductance of a primary resonance compensation network, a parallel capacitance of the primary resonance compensation network, a series capacitance of the primary resonance compensation network, a transmitting coil and a receiving coil.
One end of the output end of the transmitting side full-bridge inverter is connected with one end of an inductor of the primary side resonance compensation network; the other end of the inductor of the primary side resonance compensation network is respectively connected with one end of the parallel capacitor of the primary side resonance compensation network and one end of the series capacitor of the primary side resonance compensation network; the other end of the series capacitor of the primary side resonance compensation network is connected with one end of the transmitting coil; the other end of the transmitting coil is respectively connected with the other end of the parallel capacitor of the primary side resonance compensation network and the other end of the output end of the transmitting side full-bridge inverter.
The transmitting coil is coupled with the receiving coil; one end of the receiving coil is connected with the input end of the secondary resonance compensation network series capacitor module; the other end of the receiving coil is connected with one end of the input end of the receiving side half-control rectifier bridge; and the output end of the secondary resonance compensation network series capacitor module is connected with the other end of the input end of the receiving side half-control rectifier bridge.
The secondary resonance compensation network series capacitance module comprises a first MOSFET, a second MOSFET, a parallel capacitance of the secondary resonance compensation network and a series capacitance of the secondary resonance compensation network; the source electrode of the first MOSFET is connected with one end of the receiving coil; the drain electrode of the first MOSFET is connected with the drain electrode of the second MOSFET; the source electrode of the second MOSFET is connected with one end of the series capacitor of the secondary resonance compensation network; the other end of the series capacitor of the secondary resonance compensation network is connected with the other end of the input end of the receiving side half-control rectifier bridge; one end of a parallel capacitor of the secondary resonance compensation network is connected with one end of the receiving coil; the other end of the parallel capacitor of the secondary resonance compensation network is connected with the source electrode of the second MOSFET.
As a specific embodiment, the receiving side half-controlled rectifier bridge includes a first rectifier diode, a second rectifier diode, a receiving side first MOSFET and a receiving side second MOSFET;
the other end of the series capacitor of the secondary resonance compensation network is respectively connected with the anode of the first rectifying diode and the drain electrode of the receiving side first MOSFET; the cathode of the first rectifying diode is connected with the cathode of the second rectifying diode and one end of the load respectively; the source electrode of the first MOSFET at the receiving side is respectively connected with the source electrode of the second MOSFET at the receiving side and the other end of the load; the other end of the receiving coil is connected with the anode of the second rectifying diode and the drain electrode of the second MOSFET at the receiving side respectively.
Further, the wireless charging system further comprises a filter capacitor; the filter capacitor is respectively connected with one end of the load and the other end of the load.
As a specific embodiment, the transmitting-side full-bridge inverter includes a transmitting-side first MOSFET, a transmitting-side second MOSFET, a transmitting-side third MOSFET, a transmitting-side fourth MOSFET, and a power source.
The positive electrode of the power supply is respectively connected with the drain electrode of the first MOSFET at the transmitting side and the drain electrode of the third MOSFET at the transmitting side; the negative electrode of the power supply is respectively connected with the source electrode of the second MOSFET at the transmitting side and the source electrode of the fourth MOSFET at the transmitting side; one end of an inductor of the primary side resonance compensation network is connected with a source electrode of the transmitting side first MOSFET and a drain electrode of the transmitting side second MOSFET respectively; the other end of the transmitting coil is connected with the source electrode of the transmitting side third MOSFET and the drain electrode of the transmitting side fourth MOSFET respectively.
In practical application, as shown in FIG. 1, S 1 ～S 4 The transmitting-side full-bridge inverter is constituted as a MOSFET on the transmitting side. D (D) 1 ～D 2 For receiving-side rectifier diode, Q 1 ～Q 2 For the receiving-side commutating MOSFET, the two parts form a receiving-side half-controlled rectifier bridge. L (L) 1 and L2 Self-inductance of the transmitting coil and the receiving coil respectively, M is mutual inductance between the transmitting coil and the receiving coil, namely coupling coefficient, L f1 、C f1 and C1 Inductance, parallel capacitance and series capacitance of primary side resonance compensation network respectively, C 2 Series capacitance (consisting of two opposite strings of MOSFETs-Q) for a secondary side resonant compensation network a 、Q b Parallel capacitor C x Series capacitor C y Composition), V IN For primary side DC input voltage u AB For the terminal voltage of two points of the primary side A, B, u ab Is the terminal voltage of two points of the secondary sides a and b, i 1 、i 2 and iLf1 Is through L 1 、L 2 and Lf1 I is the current of (i) Cx 、i Cq The current passing through a capacitor branch in SCC and a switching tube branch in SCC, C o For the filter capacitance, R represents the load resistance and ω represents the operating frequency of the system. Wherein S is 1 A first MOSFET as the transmitting side; s is S 2 A second MOSFET on the transmitting side; s is S 3 A third MOSFET for the emission side; s is S 4 A fourth MOSFET that is the emission side; d (D) 1 Is a first rectifying diode; d (D) 2 Is a second rectifier diode; q (Q) 1 To the receiving sideA MOSFET; q (Q) 2 A second MOSFET as a receiving side; l (L) 1 Is the self-inductance of the transmitting coil; l (L) 2 Is the self-inductance of the receiving coil; c (C) 2 The capacitance of the capacitance module is connected in series for the secondary resonance compensation network; q (Q) a Is a first MOSFET; qb is the second MOSFET. In fig. 1, the reason why the positive and negative poles are labeled for the full-bridge inversion is to clarify the initial direction of the sinusoidal current, i.e., there is no need to add +/-, at the time of calculation.
Example two
In order to realize a corresponding system of the above embodiment to achieve corresponding functions and technical effects, a control method of a wireless charging system based on LCC-S compensation topology is provided below, as shown in fig. 7, where the control method includes:
step S1: and acquiring charging voltage and charging current at two ends of the load and a preset direct-current output voltage of the receiving side half-control rectifier bridge.
Step S2: and obtaining voltage gain according to the charging voltage and the preset direct current output voltage.
Step S3: calculating element parameters of the wireless charging system based on the LCC-S compensation topological junction according to the voltage gain and the topological structure of the wireless charging system based on the LCC-S compensation topological junction; the element parameters comprise the movement angle of the half-controlled rectifier bridge, the output resistance and the capacitance of the secondary resonance compensation network series capacitance module.
Step S4: determining a variable capacitance parameter according to the element parameter; the variable capacitance parameter comprises a parallel capacitance of the secondary resonance compensation network and a series capacitance of the secondary resonance compensation network.
Step S5: and determining the switching voltage at two ends of the parallel capacitor of the secondary resonance compensation network according to the variable capacitance parameter.
Step S6: and judging whether the switching voltage meets the voltage withstand requirement or not according to the judgment.
Step S7: when the switching voltage does not meet the withstand voltage requirement, the coupling coefficient of the wireless charging system based on the LCC-S compensation topological junction, the inductance of the transmitting coil and the inductance of the receiving coil are updated, and the step of 'calculating the element parameters of the wireless charging system based on the LCC-S compensation topological junction according to the voltage gain and the topological structure of the wireless charging system based on the LCC-S compensation topological junction' is performed in a return mode.
Step S8: and when the switching voltage does not meet the withstand voltage requirement, obtaining the wireless charging system with constant voltage output based on the LCC-S compensation topological junction.
Wherein, S3 specifically includes:
step S31: obtaining a moving angle of the half-control rectifier bridge according to the calculation formula of the voltage gain and the charging voltage; the calculation formula of the charging voltage is as follows: wherein ,V0 For charging voltage, M is the coupling coefficient of a coupling transformer consisting of a receiving coil and a transmitting coil, V AB For the output voltage of the full-bridge inverter on the transmitting side, L f1 The inductance of the primary side resonance compensation network is adopted, and beta is the moving angle of the half-control rectifier bridge.
Step S32: and generating PWM control signals of the first MOSFET at the receiving side and the second MOSFET at the receiving side according to the moving angle.
Step S33: and determining an output resistance according to the charging voltage and the charging current.
Step S34: according to the moving angle and the output resistance, a calculation formula of the capacitance of the secondary resonance compensation network series capacitance module is applied to determine the capacitance of the secondary resonance compensation network series capacitance module; the calculation formula of the capacitance of the secondary resonance compensation network series capacitance module is as follows: wherein ,C2 The capacitance of the capacitor module is connected in series with the compensation network for the secondary resonance, L 2 For receiving inductance of coil, R 0 Beta is the moving angle of the half-control rectifier bridge, and omega is the working frequency.
S4 specifically comprises the following steps:
according to the capacitance of the series capacitance module of the secondary resonance compensation network, the secondary resonance compensation network is appliedThe calculation formula of the parallel capacitance of the secondary resonance compensation network and the calculation formula of the series capacitance of the secondary resonance compensation network are calculated; wherein,C x parallel capacitor of secondary resonance compensation network, C y Series capacitance of secondary resonance compensation network, C 2max Is C 2 Maximum value of C 2min Is C 2 Minimum value->Is thatAt-> Maximum value of>Is->At->Is set to be a minimum value of (c),
s5 specifically comprises the following steps:
applying a calculation formula of the switching voltages at two ends of the parallel capacitor of the secondary resonance compensation network, and determining the switching voltages at two ends of the parallel capacitor of the secondary resonance compensation network according to the variable capacitance parameter; the calculation formula of the switching voltage at two ends of the parallel capacitor of the secondary resonance compensation network is as follows:
wherein ,Cx Parallel capacitor of secondary resonance compensation network, C y Series capacitance of secondary resonance compensation network, R 0 For output resistance, V AB For the output voltage of the full bridge inverter at the transmitting side, ω is the operating frequency, M is the coupling coefficient of a coupling transformer consisting of a receiving coil and a transmitting coil, L f1 Inductance of the primary side resonance compensation network, L 2 For receiving inductance of coil, M max Is the maximum value of the coupling coefficient.
In practical application, as shown in FIG. 2, at i 2 At the beginning of the positive half cycle of (2), turn on Q 1 At this time Q 2 Which means that the current does not flow through the battery but forms a circuit in the resonant cavity. When Q is 1 Shut down, Q 2 When turned on, the current passes through D 1 and D2 The battery is charged. In the negative half cycle of the current, it operates in a similar manner to the positive half cycle. It can be seen that two switches Q are added on the full-bridge uncontrolled rectifier 1 and Q2 Another degree of freedom of control (i.e. phase shift angle β) can be obtained. By setting the value to be 0 pi]And the MOSFET can be ensured to realize zero-voltage on. Thus, the equivalent resistance of the half-controlled rectifier bridge introduces a capacitive impedance compared to the pure resistance of a conventional rectifier. The equivalent impedance is as follows:
in practical application, as shown in FIG. 3, at i 2 At the beginning of the positive half cycle of Q b Is open, but the path of the switch is disconnected, and the capacitor C x The parallel path in which it is located starts discharging. At t 1 At the moment, the capacitor discharges and current begins to flow through Q a and Qb Is a non-parallel diode of (c). To t 2 When Q is a Shut off Q b Opening. Thus, the first and second substrates are bonded together,the path of the switch is opened, and the current passes through C x Thereby giving C x And (5) charging. In the negative half of the current, it works in a similar way to the positive half. In this way, by introducing the angle of movement of the switching tubeThe capacitance of the capacitor can be effectively controlled, and the specific capacitance relation is shown as follows:
to simplify the subsequent calculations, taylor expansion is performed on the above equation as follows:
C 2 the calculated relationship of the parameters of (a) is as follows:
after the fundamental wave analysis method is adopted, the system shown in the figure 1 can be simplified into an alternating current system shown in the figure 4, and in an LCC network, the compensation form is a type network so as to generate constant current I L1 The stability of the induced voltage of the receiving end is facilitated, and the parameter relation of the transmitting end is as follows:
in FIG. 4, -jωMI 2 For the induced voltage of the receiving end acting on the transmitting end, jωMI 1 Is the induced voltage applied to the receiving end by the transmitting end. Z is Z IN Z is the impedance input by the transmitting end R Z is the reflection impedance of the receiving end S For the impedance of the receiving end, the values of the impedances are as follows:
by mixing the above Z IN The simplification is obtained:
in order to reduce reactive circulation of the system and improve the efficiency of the system, the whole system needs to be ensured to be in a zero phase angle input state, so that the impedance of a receiving end needs to be ensured to be pure, namely:
jωL 2 +1/jωC 2 +jX eq ＝0 (8)
the current and voltage output in a simplified ac system is calculated as follows:
the output dc voltage is calculated as:
when X is eq Can be controlled by a variable capacitance C 2 During compensation, the output voltage and beta are in monotonous relation. That is, by modulating beta and SCC of the controllable rectifier bridgeA stable dc output voltage can be achieved with coupling ripple. Thus, a control scheme of the proposed system is shown in fig. 5. Measuring charging voltage V with a sensor o And charging current I o . A simple PI controller is arranged, and V is eliminated by adjusting beta ref And V is equal to o Errors between them. V (V) o Divided by I o Obtain the output resistance R o According to formula (1), formula (4) and formula (8) combine β with Ro to give another control variable of SCC +.>Further, through i 2 The PWM synchronization signals of SCC and SAR can be obtained. Obtaining Q from the calculated beta value and voltage gain 1 and Q2 The control signals of the PWM waves of the two mosfets, i.e. the beta value, are calculated to determine C 2 Is a voltage range. In the actual operation process, the value is generated by PI according to the error between the actual voltage and the ideal voltage, i.e. the driving duty ratio of the mosfet, and the PWM generated in this way is used for driving Q 1 and Q2 。
The switch capacitance and corresponding maximum voltage are calculated as follows. First, determine C 2 Is a range of values for (a). Substituting (1) into (8) to obtain C 2 The method comprises the following steps:
C 2 the value of (2) is equal to omega and L 2 、R o There is a correlation between the values of beta, where omega is a constant value, L 2 When the coupler is designed to be a fixed value, R o The value of beta is related to the coupling state of the system. For beta, the value interval is [0, pi ]]Therefore sin 2 (beta/2) is a monotonic function within this interval. Then the relationship of β to M can be derived from equation (10):
in the formula ,Mmax and Mmin Is the maximum and minimum mutual inductance of the system. For system design, ω, L 2 、R o The value ranges of beta and beta are known, and C can be obtained 2 Is a range of values. When C 2 After determination, C x C (C) y The values of (2) are as follows:
wherein ,C2max Is C 2 Maximum value of C 2min Is C 2 Is set to be a minimum value of (c),is->At->Maximum value of>Is->At->Is a minimum of (2).
The calculation formula of the maximum voltage value of the switch capacitor is as follows:
from equation (14), when the system parameters are determined, V cx The maximum voltage of (2) is related to R, M. For variations in R values, for V cx The bias derivative for R can be obtained:
because of and M/Mmax Less than 1, thus->Thereby obtaining V for cx Maximum value that can be taken at minimum R value.
For the change of M value, V is cx Simplified to the following formula:
as shown in FIG. 6, set M/M max ∈[0.2，1]Then in this interval g (M) is a convex function. At the same time, h (M) is always a monotonically increasing function, so V can be obtained cx Is a concave function about M.
According to V cx For the relationship between R and M, V can be obtained cx The maxima of (c) may be taken at two points and where rmnim and mmx, rmnim and mmx. In practical application, in order to ensure the working reliability of the device, V cx Should be less than 80% of the available MOSFET drain-source voltage. If the requirements are not met, the magnetic coupler can be iterated to obtain a lower V cx 。
In addition, the invention also provides C under the offset working condition 2 The initial value adjustment process of (1) is as follows:
in order to compensate the change of the coupler self-inductance under the offset working condition and enable the receiving end to work in the minimum reactive current state, C is needed to be adjusted according to the offset condition 2 Is adjusted. In order to make C2 and L2 in resonance state under the lateral, longitudinal and angular offsets, C as shown in FIG. 8 is proposed 2 And (5) initial value adjustment flow.
First, since the conduction angle β of the SAR is set to pi, the SAR is equivalent to a normal rectifier bridge, so that C can be adjusted more easily 2 Initial value of (1) and L 2 Resonance. The output current value at this time is shown as follows:
when C 2 And L is equal to 2 At resonance, i 2 Maximum, thus, adjust C 2 A kind of electronic deviceValue, once the output current reaches a maximum value, it can be concluded that C 2 Has been combined with L 2 In a resonant state.
According to the control method of the wireless charging system based on the LCC-S compensation topological junction, provided by the invention, the association among the parameters of each component is analyzed and the parameter relation among the components is determined by calculating the constant voltage output condition under the condition that the LCC-S topology is combined with SAR and SCC to realize offset. Meanwhile, a set of calculation flow considering the maximum voltage of the SCC under the offset working condition is provided for calculating the influence of system parameters on the voltage of the SCC, and an SCC initial value adjustment strategy of reactive minimization of a receiving end is designed.
The control method of the wireless charging system based on the LCC-S compensation topological junction has the following advantages:
1. compared with the existing single control method of the cascade DC-DC at the receiving side, the parameter setting method for realizing single-side control constant voltage output under the offset working condition based on the WPT system combining SAR and SCC by the LCC-S network saves extra energy storage capacitance and inductance, and reduces the system volume; compared with a unilateral SAR method, the method takes coupling fluctuation into consideration, simplifies the parameterized design process, can realize CV and minimum reactive power at the same time by controlling SCC and SAR, and improves the system efficiency.
2. Compared with a double-end cooperative control method, the control scheme is based on fixed working frequency and real-time adjustment of a receiving end, closed-loop output adjustment independent of wireless communication is achieved, and control stability and instantaneity are improved.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (8)
1. The wireless charging system based on the LCC-S compensation topological junction is characterized by comprising a transmitting side full-bridge inverter, a receiving side half-control rectifier bridge, a secondary resonance compensation network series capacitor module, an inductor of a primary side resonance compensation network, a parallel capacitor of the primary side resonance compensation network, a series capacitor of the primary side resonance compensation network, a transmitting coil and a receiving coil;
one end of the output end of the transmitting side full-bridge inverter is connected with one end of an inductor of the primary side resonance compensation network; the other end of the inductor of the primary side resonance compensation network is respectively connected with one end of the parallel capacitor of the primary side resonance compensation network and one end of the series capacitor of the primary side resonance compensation network; the other end of the series capacitor of the primary side resonance compensation network is connected with one end of the transmitting coil; the other end of the transmitting coil is respectively connected with the other end of the parallel capacitor of the primary side resonance compensation network and the other end of the output end of the transmitting side full-bridge inverter;
the transmitting coil is coupled with the receiving coil; one end of the receiving coil is connected with the input end of the secondary resonance compensation network series capacitor module; the other end of the receiving coil is connected with one end of the input end of the receiving side half-control rectifier bridge; the output end of the secondary resonance compensation network series capacitor module is connected with the other end of the input end of the receiving side half-control rectifier bridge;
the secondary resonance compensation network series capacitance module comprises a first MOSFET, a second MOSFET, a parallel capacitance of the secondary resonance compensation network and a series capacitance of the secondary resonance compensation network; the source electrode of the first MOSFET is connected with one end of the receiving coil; the drain electrode of the first MOSFET is connected with the drain electrode of the second MOSFET; the source electrode of the second MOSFET is connected with one end of the series capacitor of the secondary resonance compensation network; the other end of the series capacitor of the secondary resonance compensation network is connected with the other end of the input end of the receiving side half-control rectifier bridge; one end of a parallel capacitor of the secondary resonance compensation network is connected with one end of the receiving coil; the other end of the parallel capacitor of the secondary resonance compensation network is connected with the source electrode of the second MOSFET.
2. The LCC-S compensation topology based wireless charging system of claim 1, wherein the receive side half-controlled rectifier bridge comprises a first rectifier diode, a second rectifier diode, a receive side first MOSFET, and a receive side second MOSFET;
the other end of the series capacitor of the secondary resonance compensation network is respectively connected with the anode of the first rectifying diode and the drain electrode of the receiving side first MOSFET; the cathode of the first rectifying diode is connected with the cathode of the second rectifying diode and one end of the load respectively; the source electrode of the first MOSFET at the receiving side is respectively connected with the source electrode of the second MOSFET at the receiving side and the other end of the load; the other end of the receiving coil is connected with the anode of the second rectifying diode and the drain electrode of the second MOSFET at the receiving side respectively.
3. The LCC-S compensation topology based wireless charging system of claim 2, further comprising a filter capacitor; the filter capacitor is respectively connected with one end of the load and the other end of the load.
4. The LCC-S compensation topology based wireless charging system of claim 1, wherein the transmit side full bridge inverter comprises a transmit side first MOSFET, a transmit side second MOSFET, a transmit side third MOSFET, a transmit side fourth MOSFET, and a power supply;
the positive electrode of the power supply is respectively connected with the drain electrode of the first MOSFET at the transmitting side and the drain electrode of the third MOSFET at the transmitting side; the negative electrode of the power supply is respectively connected with the source electrode of the second MOSFET at the transmitting side and the source electrode of the fourth MOSFET at the transmitting side; one end of an inductor of the primary side resonance compensation network is connected with a source electrode of the transmitting side first MOSFET and a drain electrode of the transmitting side second MOSFET respectively; the other end of the transmitting coil is connected with the source electrode of the transmitting side third MOSFET and the drain electrode of the transmitting side fourth MOSFET respectively.
5. A control method of a wireless charging system based on an LCC-S compensation topological junction, which is applied to the wireless charging system based on an LCC-S compensation topological junction according to any one of claims 1 to 4, the control method comprising:
acquiring charging voltage and charging current at two ends of a load and preset direct-current output voltage of a receiving side half-control rectifier bridge;
obtaining voltage gain according to the charging voltage and the preset direct current output voltage;
calculating element parameters of the wireless charging system based on the LCC-S compensation topological junction according to the voltage gain and the topological structure of the wireless charging system based on the LCC-S compensation topological junction; the element parameters comprise the moving angle of the half-controlled rectifier bridge, the output resistance and the capacitance of the secondary resonance compensation network series capacitance module;
determining a variable capacitance parameter according to the element parameter; the variable capacitance parameters comprise a parallel capacitance of the secondary resonance compensation network and a series capacitance of the secondary resonance compensation network;
determining the switching voltage at two ends of a parallel capacitor of the secondary resonance compensation network according to the variable capacitance parameter;
judging whether the switching voltage meets the withstand voltage requirement according to the condition;
when the switching voltage does not meet the withstand voltage requirement, updating the coupling coefficient of the wireless charging system based on the LCC-S compensation topological junction, the inductance of the transmitting coil and the inductance of the receiving coil, and returning to the execution step of calculating element parameters of the wireless charging system based on the LCC-S compensation topological junction according to the voltage gain and the topological structure of the wireless charging system based on the LCC-S compensation topological junction;
and when the switching voltage does not meet the withstand voltage requirement, obtaining the wireless charging system with constant voltage output based on the LCC-S compensation topological junction.
6. The method for controlling a wireless charging system based on an LCC-S compensation topology according to claim 5, wherein calculating the element parameters of the wireless charging system based on the LCC-S compensation topology according to the voltage gain and the topology of the wireless charging system based on the LCC-S compensation topology specifically comprises:
obtaining a moving angle of the half-control rectifier bridge according to the calculation formula of the voltage gain and the charging voltage; the calculation formula of the charging voltage is as follows:
wherein ,V0 For charging voltage, M is the coupling coefficient of a coupling transformer consisting of a receiving coil and a transmitting coil, V AB For the output voltage of the full-bridge inverter on the transmitting side, L f1 The inductance of the primary side resonance compensation network is adopted, and beta is the moving angle of the half-control rectifier bridge;
generating PWM control signals of a first MOSFET at the receiving side and a second MOSFET at the receiving side according to the moving angle;
determining an output resistance according to the charging voltage and the charging current;
according to the moving angle and the output resistance, a calculation formula of the capacitance of the secondary resonance compensation network series capacitance module is applied to determine the capacitance of the secondary resonance compensation network series capacitance module; the calculation formula of the capacitance of the secondary resonance compensation network series capacitance module is as follows:
wherein ,C2 The capacitance of the capacitor module is connected in series with the compensation network for the secondary resonance, L 2 For receiving inductance of coil, R 0 Beta, being the output resistanceIs the direction-shifting angle of the half-controlled rectifier bridge, and omega is the working frequency.
7. The method for controlling a wireless charging system based on LCC-S compensation topology according to claim 6, wherein determining the variable capacitance parameter according to the element parameter comprises:
according to the capacitance of the secondary resonance compensation network series capacitance module, a calculation formula of the parallel capacitance of the secondary resonance compensation network and a calculation formula of the series capacitance of the secondary resonance compensation network are applied, and the parallel capacitance of the secondary resonance compensation network and the series capacitance of the secondary resonance compensation network are calculated; wherein,C x parallel capacitor of secondary resonance compensation network, C y Series capacitance of secondary resonance compensation network, C 2max Is C 2 Maximum value of C 2min Is C 2 Minimum value->Is thatAt-> Maximum value of>Is->At->Is set to be a minimum value of (c),
8. the method for controlling a wireless charging system based on LCC-S compensation topology according to claim 7, wherein determining the switching voltage across the shunt capacitance of the secondary resonant compensation network according to the variable capacitance parameter, specifically comprises:
applying a calculation formula of the switching voltages at two ends of the parallel capacitor of the secondary resonance compensation network, and determining the switching voltages at two ends of the parallel capacitor of the secondary resonance compensation network according to the variable capacitance parameter;
the calculation formula of the switching voltage at two ends of the parallel capacitor of the secondary resonance compensation network is as follows:
B＝(ω 2 L 2 C x -C x /C y +0.053)/0.515
A＝3.023；
wherein ,Cx Parallel capacitor of secondary resonance compensation network, C y Series capacitance of secondary resonance compensation network, R 0 For output resistance, V AB For the output voltage of the full bridge inverter at the transmitting side, ω is the operating frequency, M is the coupling coefficient of a coupling transformer consisting of a receiving coil and a transmitting coil, L f1 Inductance of the primary side resonance compensation network, L 2 For receiving inductance of coil, M max Is the maximum value of the coupling coefficient.
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| CN117375262B (en) * | 2023-12-08 | 2024-02-20 | 电子科技大学(深圳)高等研究院 | High-power wireless power transmission system and phase shift control method |
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| CN117458736A (en) * | 2023-11-10 | 2024-01-26 | 烟台哈尔滨工程大学研究院 | Self-adaptive resonant WPT system based on energy negative feedback |
| CN117375262B (en) * | 2023-12-08 | 2024-02-20 | 电子科技大学(深圳)高等研究院 | High-power wireless power transmission system and phase shift control method |
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