A wireless power transfer control method with controllable output

Abstract

The present application discloses a control method for wireless power transmission with controllable output. The control method is implemented through a control circuit, which includes a primary full-bridge circuit, an LCC-S compensation network, a secondary uncontrolled rectifier circuit, a sampling circuit, and a control circuit. The method includes: constructing an equivalent simplified circuit for the control circuit and setting initial parameters; analyzing the equivalent simplified circuit based on the fundamental wave approximation method and constructing voltage-current equivalent equations according to the initial parameters; introducing a detuning coefficient, performing detuning analysis on the equivalent simplified circuit according to the voltage-current equivalent equations, calculating the detuning coefficient, and obtaining a calculated value of the detuning coefficient; calculating the equivalent input impedance angle of the primary circuit based on the calculated value of the detuning coefficient; and driving ZVS wireless power transmission control according to the equivalent input impedance angle based on the detuning value constraint and the impedance value constraint. The present application can solve the technical problems that the existing circuit structure and ZVS control method are relatively complex, cannot meet the control requirements of actual scenarios, and will also increase the difficulty of system maintenance.

Description

Technical Field

[0001] This application relates to the field of wireless charging technology, and particularly to a method for controlling wireless power transmission with controllable output. Background Art

[0002] With the continuous progress of wireless charging technology, new energy electric vehicles are also constantly updated and iterated, and the demand for wireless charging is increasing day by day. Especially in terms of charging efficiency and the selection of charging modes, with the changes in different application scenarios, different resonant compensation topologies can be adopted to achieve unique output characteristics, so as to realize constant current or constant voltage control. However, although wireless charging technology has great potential, there are still many problems in practical applications. At the same time, under certain specific topological structures, only specific charging modes can be supported, which limits the flexibility and optimization space of the system. At the same time, in the field of wireless power transmission at present, it is necessary to obtain an AC source after inverting a DC source, but ZVS, that is, zero voltage switching, cannot be achieved under non-detuned conditions of the system; this leads to an excessive peak in the resonant current of the system, thus breaking down the components on the circuit board.

[0003] The circuit topological structure on which the existing wireless power transmission control method is based is too complex, and too many components will increase the overall cost of the system; moreover, the existing zero voltage switching control method is also relatively complex, which cannot meet the control requirements of actual scenarios and will also increase the difficulty of system maintenance. Summary of the Invention

[0004] This application provides a method for controlling wireless power transmission with controllable output, which is used to solve the technical problems that the circuit topological structure and the zero voltage switching control method of the existing technology are both relatively complex, cannot meet the control requirements of actual scenarios, and will also increase the difficulty of system maintenance.

[0005] In view of this, this application provides a method for controlling wireless power transmission with controllable output. The control method is implemented through a control circuit, and the control circuit includes: a primary full-bridge circuit, an LCC-S compensation network, a secondary uncontrolled rectifier circuit, a sampling circuit, and a control circuit;

[0006] The primary full-bridge circuit includes 4 MOSFET switching tubes, and two of the MOSFET switching tubes form a primary bridge arm, and ZVS zero voltage switching is realized based on phase-shift control;

[0007] The LCC-S compensation network includes a primary coil, a primary compensation inductor, and a primary compensation capacitor, and the primary compensation inductor is connected in parallel with 2 of the primary compensation capacitors to form a T-shaped structure;

[0008] The secondary uncontrolled rectifier circuit includes a secondary full-bridge circuit and a secondary compensation network;

[0009] The sampling circuit is used to collect the current of the primary full-bridge circuit and the voltage of the secondary full-bridge circuit;

[0010] The control circuit includes a PWM drive circuit, a PID control circuit, and a DSP control circuit, and is used to control wireless power transmission;

[0011] The control method includes:

[0012] Construct an equivalent simplified circuit for the control circuit and set initial parameters;

[0013] Analyze the equivalent simplified circuit based on the fundamental wave approximation method, and construct a voltage-current equivalent equation according to the initial parameters;

[0014] Introduce a detuning coefficient, perform detuning analysis on the equivalent simplified circuit according to the voltage-current equivalent equation, and calculate the detuning coefficient to obtain a calculated value of the detuning coefficient;

[0015] Calculate the equivalent input impedance angle of the primary circuit based on the calculated value of the detuning coefficient;

[0016] Based on the detuning value constraint and the impedance value constraint, drive the ZVS zero-voltage turn-on control according to the equivalent input impedance angle to achieve wireless power transmission control.

[0017] Preferably, the first MOSFET switch tube and the second MOSFET switch tube in the primary full-bridge circuit form a primary leading arm;

[0018] The third MOSFET switch tube and the fourth MOSFET switch tube form a primary lagging arm;

[0019] Control the ZVS zero-voltage turn-on of the MOSFET switch tubes of the primary leading arm and the primary lagging arm by presetting a phase shift angle.

[0020] Preferably, one end of the primary coil in the LCC-S compensation network is connected in series with the primary compensation capacitor and the primary compensation inductor and then connected to the positive end of the midpoint of the primary bridge arm in the primary full-bridge circuit;

[0021] The other end of the primary coil in the LCC-S compensation network is connected to the negative end of the midpoint of the primary bridge arm in the primary full-bridge circuit.

[0022] Preferably, the secondary full-bridge circuit includes 4 symmetric diodes, and the output ends are respectively connected in parallel with a filter capacitor and a load;

[0023] The secondary compensation network includes a receiving coil and a secondary compensation capacitor, and the secondary compensation network is connected to the midpoint of the secondary bridge arm in the secondary full-bridge circuit.

[0024] Preferably, the DSP control circuit generates a PID control instruction according to the current and voltage collected by the sampling circuit;

[0025] The PID control circuit generates a conduction angle according to the PID control instruction, and triggers the PWM drive circuit through the conduction angle to drive the operation of the primary full-bridge circuit.

[0026] Preferably, introducing a detuning coefficient, performing detuning analysis on the equivalent simplified circuit according to the voltage-current equivalent equation, and calculating the detuning coefficient to obtain a calculated value of the detuning coefficient, including:

[0027] Introducing a detuning coefficient to perform resonance adjustment on the voltage-current equivalent equation to obtain a resonant equivalent relationship equation;

[0028] Performing detuning analysis on the equivalent simplified circuit according to the resonant equivalent relationship equation, calculating the detuning coefficient, and obtaining a calculated value of the detuning coefficient.

[0029] Preferably, introducing a detuning coefficient, performing detuning analysis on the equivalent simplified circuit according to the voltage-current equivalent equation, and calculating the detuning coefficient to obtain a calculated value of the detuning coefficient, further including:

[0030] Constructing an output power expression of the system according to the calculated value of the detuning coefficient;

[0031] Taking the derivative of the detuning coefficient according to the output power expression, calculating the detuning coefficient when the partial derivative value is 0, and obtaining a reference value of the detuning coefficient.

[0032] Preferably, calculating the equivalent input impedance angle of the primary circuit according to the calculated value of the detuning coefficient, including:

[0033] Calculating the equivalent input impedance of the primary circuit according to the calculated value of the detuning coefficient and the secondary-primary reflected impedance value;

[0034] Determining the equivalent input impedance angle of the primary circuit according to the equivalent input impedance.

[0035] Preferably, based on the detuning value constraint and the impedance value constraint, driving the ZVS zero-voltage turn-on control according to the equivalent input impedance angle to achieve wireless power transfer control, further including:

[0036] When the load resistance value changes, introducing a constant current coefficient to calculate a first load output current value, and collecting a first load output voltage value, where the constant current coefficient is calculated according to the constant current condition;

[0037] Calculating the constant current phase shift angle of the primary full-bridge circuit according to the first load output current value and the first load output voltage value;

[0038] The primary full-bridge circuit is subjected to constant-current control by the PID control circuit according to the constant-current phase-shifting angle.

[0039] Preferably, based on the detuning value constraint and the impedance value constraint, driving ZVS zero-voltage turn-on control according to the equivalent input impedance angle to achieve wireless power transfer control further includes:

[0040] In the case of a change in the load resistance value, a constant-voltage coefficient is introduced to calculate the second load output current value, and the second load output voltage value is collected. The constant-voltage coefficient is calculated according to the constant-voltage condition;

[0041] Calculate the constant-voltage phase-shifting angle of the primary full-bridge circuit according to the second load output current value and the second load output voltage value;

[0042] The primary full-bridge circuit is subjected to constant-voltage control by the PID control circuit according to the constant-voltage phase-shifting angle.

[0043] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0044] In the present application, a wireless power transfer control method with controllable output is provided. The control method is implemented through a control circuit, and the control circuit includes: a primary full-bridge circuit, an LCC-S compensation network, a secondary uncontrolled rectifier circuit, a sampling circuit, and a control circuit; the primary full-bridge circuit includes 4 MOSFET switching tubes, and two MOSFET switching tubes form a primary bridge arm, and ZVS zero-voltage turn-on is achieved based on phase-shift control; the LCC-S compensation network includes a primary coil, a primary compensation inductor, and a primary compensation capacitor, and the primary compensation inductor is connected in parallel with 2 primary compensation capacitors to form a T-shaped structure; the secondary uncontrolled rectifier circuit includes a secondary full-bridge circuit and a secondary compensation network; the sampling circuit is used to collect the current of the primary full-bridge circuit and the voltage of the secondary full-bridge circuit; the control circuit includes a PWM drive circuit, a PID control circuit, and a DSP control circuit for controlling wireless power transfer.

[0045] The control method includes: constructing an equivalent simplified circuit for the control circuit and setting initial parameters; analyzing the equivalent simplified circuit based on the fundamental wave approximation method and constructing a voltage-current equivalent equation according to the initial parameters; introducing a detuning coefficient, performing detuning analysis on the equivalent simplified circuit according to the voltage-current equivalent equation, and calculating the detuning coefficient to obtain a calculated value of the detuning coefficient; calculating the equivalent input impedance angle of the primary circuit based on the calculated value of the detuning coefficient; based on the detuning value constraint and the impedance value constraint, driving ZVS zero-voltage turn-on control according to the equivalent input impedance angle to achieve wireless power transfer control.

[0046] The wireless power transfer control method with controllable output provided by this application realizes the wireless power transfer control with zero-voltage turn-on of the MOSFET switch tube through the designed control circuit combined with the control method. During this process, the phase-shift control under the detuning condition is considered; based on the equivalent simplified circuit and parameter calculation, the equivalent input impedance angle for driving the ZVS zero-voltage turn-on control is determined, and the wireless power transfer control process is restricted by the detuning value constraint and the impedance value constraint, which can ensure that this process is more in line with the actual situation and the control effect is more accurate and reliable; moreover, the circuits and operations involved in the process are simple and easy to execute, and can meet the control requirements of the actual application scenario. Therefore, this application can solve the technical problems that the existing circuit topology and zero-voltage turn-on control method are relatively complex, cannot meet the control requirements of the actual scenario, and will increase the difficulty of system maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the control circuit structure of a wireless power transfer control method with controllable output provided by an embodiment of this application;

[0048] Figure 2 Schematic diagram of the flow of a wireless power transfer control method with controllable output provided by an embodiment of this application;

[0049] Figure 3 Schematic diagram of the control circuit of the primary full-bridge circuit with phase-shift control provided by an embodiment of this application;

[0050] Figure 4 Schematic diagram of the equivalent simplified circuit principle corresponding to the control circuit provided by an embodiment of this application;

[0051] Figure 5 Schematic diagram of the equivalent topology of the primary circuit under the detuning condition provided by an embodiment of this application;

[0052] Figure 6 Schematic diagram of the relationship between the system output voltage and output current after phase-shift control under the detuning condition provided by an embodiment of this application;

[0053] Figure 7 Schematic diagram of the switching signal with phase-shift control and the waveform of the system output voltage after phase-shift control provided by an embodiment of this application;

[0054] Figure 8 Schematic diagram of the relationship between the phase-shift conduction angle and the load resistance value under the constant current and constant voltage conditions provided by an embodiment of this application;

[0055] Figure 9 Schematic diagram of the relationship between the load output current and output voltage and the load resistance value under different modes provided by an embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0057] For ease of understanding, please refer to Figure 1 , an embodiment of a wireless power transmission control method with controllable output provided by this application. The control method is implemented through a control circuit, and the control circuit includes: a primary full-bridge circuit, an LCC-S compensation network, a secondary uncontrolled rectifier circuit, a sampling circuit, and a control circuit.

[0058] The primary full-bridge circuit includes 4 MOSFET switch tubes, and two MOSFET switch tubes form a primary bridge arm, achieving ZVS zero-voltage turn-on based on phase-shift control;

[0059] The LCC-S compensation network includes a primary coil, a primary compensation inductor, and a primary compensation capacitor. The primary compensation inductor is connected in parallel with 2 primary compensation capacitors to form a T-shaped structure;

[0060] The secondary uncontrolled rectifier circuit includes a secondary full-bridge circuit and a secondary compensation network;

[0061] The sampling circuit is used to collect the current of the primary full-bridge circuit and the voltage of the secondary full-bridge circuit;

[0062] The control circuit includes a PWM drive circuit, a PID control circuit, and a DSP control circuit, and is used to control wireless power transmission.

[0063] Further, the first MOSFET switch tube and the second MOSFET switch tube in the primary full-bridge circuit form a primary leading arm;

[0064] The third MOSFET switch tube and the fourth MOSFET switch tube form a primary lagging arm;

[0065] The ZVS zero-voltage turn-on of the MOSFET switch tubes of the primary leading arm and the primary lagging arm is controlled by presetting the phase-shift angle.

[0066] Further, one end of the primary coil in the LCC-S compensation network is connected to the positive end of the midpoint of the primary bridge arm in the primary full-bridge circuit after being connected in series with a primary compensation capacitor and a primary compensation inductor;

[0067] The other end of the primary coil in the LCC-S compensation network is connected to the negative end of the midpoint of the primary bridge arm in the primary full-bridge circuit.

[0068] Furthermore, the secondary full-bridge circuit includes 4 symmetrical diodes, and the output terminals are respectively connected in parallel with the filter capacitor and the load;

[0069] The secondary compensation network includes a receiving coil and a secondary compensation capacitor, and the secondary compensation network is connected to the midpoint of the secondary bridge arm in the secondary full-bridge circuit.

[0070] Furthermore, the DSP control circuit generates a PID control instruction according to the current and voltage collected by the sampling circuit;

[0071] The PID control circuit generates a conduction angle according to the PID control instruction, and triggers the PWM drive circuit through the conduction angle to drive the operation of the primary full-bridge circuit.

[0072] It should be noted that the control method of this embodiment needs to cooperate with a specific control circuit. The control circuit includes, in addition to the primary full-bridge circuit, the LCC-S compensation network, the secondary uncontrolled rectifier circuit, the sampling circuit and the control circuit; it also includes some specific coils, such as the transmitting coil and the receiving coil; in addition, it also includes the connected load.

[0073] Figure 1 The primary full-bridge circuit in includes four MOSFET switch tubes; the first MOSFET switch tube and the second MOSFET switch tube constitute the first primary bridge arm, which is also the primary leading arm; the third MOSFET switch tube and the fourth MOSFET switch tube constitute the second primary bridge arm, which is also the primary lagging arm. By introducing a phase shift angle, the on-time of the MOSFET switch tubes of the leading arm and the lagging arm can be controlled, so as to achieve the phase shift control of the four MOSFET switch tubes.

[0074] The LCC-S compensation network is the primary compensation network. This topology can support the realization of ZVS zero-voltage turn-on control under the detuning condition while ensuring the constant current or constant voltage output of the system. The network specifically includes a primary coil a primary compensation inductor and a primary compensation capacitor and The primary compensation inductor is connected in parallel with 2 primary compensation capacitors , to form a T-shaped structure. In addition, one end of the primary coil is sequentially connected in series with a primary compensation capacitor and a primary compensation inductor and then connected to the positive end of the midpoint of the primary bridge arm in the primary full-bridge circuit; while the other end of the primary coil is connected to the negative end of the midpoint of the primary bridge arm.

[0075] The secondary uncontrolled rectifier current also includes a full-bridge circuit and a compensation network, namely, a secondary full-bridge circuit and a secondary compensation network. Specifically, the secondary full-bridge circuit is composed of 4 symmetric diodes, and the output terminals are connected in parallel with the filter capacitor and the load . One end of the receiving coil of the secondary compensation network is connected in series with the secondary compensation capacitor and then connected to the positive end of the midpoint of the secondary bridge arm, while the other end is connected to the negative end of the midpoint of the secondary bridge arm.

[0076] Figure 1 The control part of Figure 3 includes a sampling circuit and a control circuit. The sampling circuit includes a current sampling circuit and a voltage sampling circuit; the current sampling circuit is mainly used to collect the current at the positive end of the midpoint of the primary bridge arm, while the voltage sampling circuit is used to collect the actual voltage across the load. The control circuit includes a PWM drive circuit, a PID control circuit, and a DSP control circuit. The combination of several control circuits can achieve the wireless power transfer control of ZVS. Specifically, the DSP control circuit generates a PID control instruction according to the current and voltage collected by the sampling circuit; the PID control circuit generates a conduction angle according to the PID control instruction and triggers the PWM drive circuit to drive the operation of the primary full-bridge circuit through the conduction angle. In addition, the phase-shift control circuit of the primary full-bridge circuit can refer to Figure 3 .

[0077] Please refer to Figure 2 , and the control method includes:

[0078] Step 101: Construct an equivalent simplified circuit for the control circuit and set the initial parameters.

[0079] The equivalent simplified circuit constructed for the control circuit in this embodiment can be referred to Figure 4 . Since the parasitic resistance value of the circuit is small, in order to simplify the theoretical analysis, the parasitic resistance in the circuit is ignored in this embodiment. Necessary circuit initial parameters can be set according to the circuit construction requirements, and specific details are not limited here.

[0080] Step 102: Analyze the equivalent simplified circuit based on the fundamental wave approximation method and construct a voltage-current equivalent equation according to the initial parameters.

[0081] Analyze Figure 4 's equivalent simplified circuit. Circuit analysis can be performed based on the fundamental wave approximation method, and then a voltage-current equivalent equation can be constructed according to the initial parameters:

[0082]

[0083] Among them,

[0084]

[0085] Among them, is the resonant inductor of the primary side, which is connected in series at the transmitting end. The parallel resonant capacitor at the transmitting end is , and the series compensation capacitor is . In addition, the self-inductance of the transmitting coil is , the self-inductance of the receiving coil is , and the compensation capacitor at the receiving end is , which is connected in series at the receiving end. is the overall working angular frequency of the system, is the switching frequency of the MOSFET switch tube in the system, is the mutual inductance value between the transmitting coil and the receiving coil. is the AC equivalent load resistance of the secondary circuit system before rectification, is the load value carried by the circuit output. is the impedance of the resonant inductor ; is the impedance of the resonant capacitor ; is the total impedance of the series connection of the inductance value of the transmitting coil and the resonant capacitor ; is the total impedance of the series connection of the self-inductance value of the receiving coil and the resonant compensation capacitor ; is the DC power supply voltage input to the circuit; is the output voltage after inversion by the primary full-bridge circuit; please refer to Figure 5 , , , are the current flowing through the resonant inductor in the first loop, the current flowing through the transmitting coil in the second loop, and the current flowing through the equivalent load resistance in the third loop, respectively.

[0086] Step 103: Introduce a detuning coefficient, perform detuning analysis on the equivalent simplified circuit according to the voltage-current equivalent equation, and calculate the detuning coefficient to obtain the calculated value of the detuning coefficient.

[0087] Furthermore, step 103 includes:

[0088] Introduce a detuning coefficient to perform resonance adjustment on the voltage-current equivalent equation to obtain a resonance equivalent relationship equation;

[0089] Perform detuning analysis on the equivalent simplified circuit according to the resonance equivalent relationship equation, calculate the detuning coefficient, and obtain the calculated value of the detuning coefficient.

[0090] It should be noted that, since the existing MOSFET switch tube cannot achieve ZVS control, it will cause excessive MOSFET switching losses, thereby reducing the transmission efficiency of the system. Therefore, phase shift control under system detuning conditions is introduced to achieve zero voltage turn-on of the MOSFET switch tube through design parameters.

[0091] Figure 5 In this embodiment, the detuning coefficient is introduced to analyze the detuning of the system, so that Figure 5 The resonant inductor in the first loop With resonant capacitor There is no quasi-resonance between the two, so the voltage-current equivalent equation , , It can be converted to:

[0092]

[0093] Then the resonant capacitor in the second loop , and the transmitting coil self-inductance Quasi-resonance occurs between the three, which means that the primary circuit is inductive as a whole.

[0094] See also Figure 6 In full-bridge phase-shift control, the voltage output by the primary circuit of the phase-shift control is required to be ahead of its output current as a whole, so as to achieve the ZVS zero voltage turn-on of the four symmetrical MOSFET switches of the primary voltage. In the ZVS control mode, the voltage of the MOSFET switch tube will first drop to 0 and then turn on; therefore, the turn-on of the MOSFET switch tube occurs at zero voltage, thus avoiding the switching loss caused by the simultaneous existence of voltage and current; reducing the spike effect caused by the sudden change of voltage and current during the switching process, reducing the switching loss and improving the system efficiency.

[0095] Combining the above formulas, we can get some current parameters of the system:

[0096]

[0097] According to the above analysis, it can be found that the output voltage and current of the system circuit are both related to the equivalent load resistance. That is, when ZVS control is implemented, if the load resistance of the system changes, the system cannot achieve constant current or constant voltage output.

[0098] Combination , , The expression and Figure 5 Detuning analysis can be performed to calculate the detuning coefficient: The resonant capacitor can also be determined simultaneously , and . Therefore, the overall expression of the relevant parameters that can be determined in this analysis is:

[0099]

[0100] According to the detuning coefficient expression, the detuning coefficient can be assumed first. According to the formula, the resonant inductor parameters are set first, and the resonant capacitor at this time is estimated. On this basis, the resonant capacitor is gradually increased, and a suitable is selected to satisfy . So that the detuning coefficient at this time. That is, the detuning coefficient is a parameter that can be adjusted according to the resonant capacitor . The detuning coefficient is dynamically updated according to the regulation requirements of the context, so as to achieve a more reliable ZVS zero-voltage turn-on.

[0101] Furthermore, step 103 also includes:

[0102] Construct an output power expression of the system based on the detuning coefficient;

[0103] Derive the detuning coefficient according to the output power expression, calculate the detuning coefficient when the partial derivative value is 0, and obtain the detuning coefficient reference value.

[0104] Since the resonant inductor on the primary side is a parameter that can be considered set, there may still be a certain error in the calculated value of the detuning coefficient, and its accuracy and reliability cannot be ensured. Therefore, in this embodiment, a detuning coefficient reference value is calculated again by optimizing the system power, and the detuning coefficient is normatively constrained based on the detuning coefficient reference.

[0105] In order to make the system output a higher output power at all times and improve the transmission efficiency of the system, an output power expression of the system under constant current or constant voltage conditions can be constructed, that is, the output power expression:

[0106]

[0107] In order to clarify the relationship between the detuning coefficient and the system output power , by taking the first-order partial derivative of and setting the partial derivative to 0, the detuning coefficient reference value can be obtained:

[0108]

[0109] Since the second-order partial derivative of the formula is less than 0, that is The selected value can make the system output power reach the maximum value. Therefore, the calculated value of the detuning coefficient should be as close as possible to the reference value of the detuning coefficient . Therefore, a constraint can be set for the detuning value in this embodiment: .

[0110] Step 104: Calculate the equivalent input impedance angle of the primary circuit according to the calculated value of the detuning coefficient.

[0111] Further, step 104 includes:

[0112] Calculate the equivalent input impedance of the primary circuit according to the calculated value of the detuning coefficient and the primary-secondary reflected impedance value;

[0113] Determine the equivalent input impedance angle of the primary circuit according to the equivalent input impedance.

[0114] According to Figure 5 and the calculated value of the detuning coefficient and the primary-secondary reflected impedance value the equivalent input impedance of the primary voltage can be calculated:

[0115]

[0116] Among them, the primary-secondary reflected impedance value refers to the impedance value reflected from the secondary receiving coil to the primary transmitting coil, and can be expressed as:

[0117]

[0118] Combining the above three current parameter expressions, we can get:

[0119]

[0120] According to the equivalent input impedance expression, the equivalent input impedance angle of the primary circuit can be determined:

[0121]

[0122] The value range of the equivalent input impedance angle is , and it is necessary to judge whether the calculated equivalent input impedance angle can be directly used for system control whether it holds. If it holds, it can be used for subsequent control; otherwise, reselect the parameters and adjust the detuning coefficient.

[0123] Step 105: Based on the detuning value constraint and the impedance value constraint, drive the ZVS zero-voltage turn-on control according to the equivalent input impedance angle to achieve wireless power transfer control.

[0124] The detuning value constraint includes , and also requires that the calculated detuning coefficient value must be greater than 1, that is ; while the impedance value constraint refers to , is the phase shift angle, which can be set according to the actual situation; the mutual inductance value satisfies:

[0125]

[0126] Specifically, its value can be selected according to the value range of the mutual inductance value between the transmitting coil and the receiving coil.

[0127] When the calculated detuning coefficient value and the equivalent input impedance angle meet the above constraints, the primary circuit can be made inductive, the input voltage is ahead of the input current, and then the ZVS zero-voltage turn-on based on phase-shift control can be achieved according to the equivalent input impedance angle.

[0128] Furthermore, Step 105 also includes:

[0129] In the case of a change in the load resistance value, introduce a constant current coefficient to calculate the first load output current value, and collect the first load output voltage value. The constant current coefficient is calculated according to the constant current condition;

[0130] Calculate the constant current phase shift angle of the primary full-bridge circuit according to the first load output current value and the first load output voltage value;

[0131] Implement constant current control of the primary full-bridge circuit through the PID control circuit according to the constant current phase shift angle.

[0132] Furthermore, Step 105 also includes:

[0133] In the case of a change in the load resistance value, introduce a constant voltage coefficient to calculate the second load output current value, and collect the second load output voltage value. The constant voltage coefficient is calculated according to the constant voltage condition;

[0134] Calculate the constant voltage phase shift angle of the primary full-bridge circuit according to the second load output current value and the second load output voltage value;

[0135] Implement constant voltage control of the primary full-bridge circuit through the PID control circuit according to the constant voltage phase shift angle.

[0136] It should be noted that please refer to Figure 7, In theory, the output voltage of the phase-shifted control primary circuit should be as follows:

[0137]

[0138] However, when the load resistance changes, the equivalent load resistance of the system will also change. At this time, the system cannot achieve constant current or constant voltage output. Therefore, this embodiment analyzes the conditions for constant current or constant voltage output control and designs specific constant current or constant voltage output control parameters.

[0139] Specifically, first perform a Fourier series expansion on the output voltage formula of the above-mentioned phase-shifted control primary circuit, and the following can be obtained:

[0140]

[0141] Since the transmitter has a filtering effect after resonance, the harmonic components of the output voltage can be filtered out. Therefore, the effective value of the output voltage is:

[0142]

[0143] Among them, the phase-shift angle has a value range of .

[0144] In the case of realizing ZVS zero-voltage control, if the load resistance value changes, the output voltage and output current of the system circuit need to remain constant. Therefore, this embodiment ensures that the system can also maintain the effect of constant current or constant voltage output when the load resistance value changes by adjusting the magnitude of the phase-shift angle.

[0145] For the case of constant current: Introduce a constant current coefficient . Thus, the relationship between the output current of the primary full-bridge circuit after phase-shifted control and the load output current is:

[0146]

[0147] It can be understood that the system input current is the output current of the primary full-bridge circuit after phase-shifted control, and the load output current is the output current of the system circuit; moreover, this formula is the condition for realizing constant current output. Combining the theoretical analysis with the equivalent equation above, the expression of the constant current coefficient can be determined:

[0148]

[0149] Suppose the required constant voltage and constant current values of the system are respectively 、 , then by using the above current relationship formula, the actual load current output value, that is, the first load output current value, can be calculated according to the collected system input current , and can be denoted as ; then the actual load voltage output value, that is, the first load output voltage value, is collected through the voltage acquisition circuit and denoted as , then the size of the load resistance value at this moment can be calculated through the DSP control circuit, and then is compared with , and the new phase shift angle, that is, the constant current phase shift angle can be calculated:

[0150]

[0151] Through the PID control circuit, according to the constant current phase shift angle , the phase shift angle of the primary circuit can be adjusted to achieve a fixed current output for the topological load.

[0152] For the constant voltage case: Introduce the constant voltage coefficient , and the relationship between the output current of the primary full-bridge circuit after phase shift control and the load output voltage is:

[0153]

[0154] Similarly, this formula is the condition for realizing constant voltage output. Combining the above equivalent equation for theoretical analysis, the expression of the constant voltage coefficient can be determined:

[0155]

[0156] Based on the above current-voltage relationship formula, according to the collected system input current , the load current output value at this moment, that is, the second load output current value, can be calculated and denoted as ; then the actual load voltage output value, that is, the second load output voltage value, is collected through the voltage acquisition circuit and denoted as , then the size of the load resistance value at this moment can be calculated through the DSP control circuit, and then is compared with , and the constant voltage phase shift angle can be calculated:

[0157]

[0158] Through the PID control circuit according to the constant voltage phase-shifting angle the phase-shifting angle of the primary circuit can be adjusted to achieve a fixed voltage output for the topological load. It can be understood that the phase-shifting angle is the phase-shifting conduction angle.

[0159] For the sake of easy understanding, taking the input DC power supply as 200V, the operating frequency as 85kHz, the transmitting coil and the receiving coil both with a size of 190 μH. The initial load resistance value is 22.5 Ω, and the initial phase-shifting conduction angle is set to 40. The introduced detuning coefficient , the mutual inductance value between the transmitting coil and the receiving coil = 66.5 μH, the resonant inductance = 150 μH, and the coefficient = 1.53, = 34.45 as an example, keeping the load output current at 4.3 A and the load output voltage at 97 V. When the load resistance value changes from 15 Ω to 30 Ω during the charging process, at this time, the relationship between the phase-shifting conduction angle ( and ) and the load resistance value is as shown in Figure 8 . In the constant current output mode, by changing the constant current phase-shifting conduction angle the output current of the load is maintained at about 4.3 A, please refer to Figure 9 . In the constant voltage output mode, by changing the constant voltage phase-shifting conduction angle the output voltage of the load is maintained at about 97 V, as shown in Figure 9 . At the same time, the relationship diagram of the phase-shifting conduction angle and the load resistance value under two different modes is given.

[0160] The wireless power transmission control method with controllable output provided by the embodiments of the present application realizes the wireless power transmission control with zero-voltage turn-on of the MOSFET switch tube through the designed control circuit in combination with the control method. During this process, the phase-shift control under the detuning condition is considered; based on the equivalent simplified circuit and parameter calculation, the equivalent input impedance angle for driving the ZVS zero-voltage turn-on control is determined, and the wireless power transmission control process is restricted through the detuning value constraint and impedance value constraint, which can ensure that this process is more in line with the actual situation and the control effect is more accurate and reliable; moreover, the circuits and operations involved in the process are simple and easy to execute, and can meet the control requirements of the actual application scenario. Therefore, the embodiments of the present application can solve the technical problems that the circuit topology and zero-voltage turn-on control method of the prior art are relatively complex, cannot meet the control requirements of the actual scenario, and will also increase the difficulty of system maintenance.

[0161] In several embodiments provided by the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point, the displayed or discussed mutual coupling or direct coupling or communication connection can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be in electrical, mechanical or other forms.

[0162] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0163] In addition, in each embodiment of the present application, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0164] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (English full name: Read-Only Memory, English abbreviation: ROM), random access memories (English full name: Random Access Memory, English abbreviation: RAM), magnetic disks, or optical discs.

[0165] As described above, the above embodiments are only used to illustrate the technical solutions of this application, rather than to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of various embodiments of this application.

Claims

1. A wireless power transmission control method with controllable output, characterized in that, The control method is implemented through a control circuit, which includes: a primary full-bridge circuit, an LCC-S compensation network, a secondary uncontrolled rectifier circuit, a sampling circuit, and a control circuit; The primary full-bridge circuit includes 4 MOSFET switches, and two of the MOSFET switches form a primary bridge arm, achieving ZVS zero-voltage turn-on based on phase-shift control; The LCC-S compensation network includes a primary coil, a primary compensation inductor, and a primary compensation capacitor. The primary compensation inductor is connected in parallel with 2 of the primary compensation capacitors to form a T-shaped structure; The secondary uncontrolled rectifier circuit includes a secondary full-bridge circuit and a secondary compensation network; The sampling circuit is used to collect the current of the primary full-bridge circuit and the voltage of the secondary full-bridge circuit; The control circuit includes a PWM drive circuit, a PID control circuit, and a DSP control circuit, which are used to control wireless power transmission; The control method includes: Construct an equivalent simplified circuit for the control circuit and set initial parameters; Analyze the equivalent simplified circuit based on the fundamental wave approximation method and construct a voltage-current equivalent equation according to the initial parameters; Introduce a detuning coefficient, perform detuning analysis on the equivalent simplified circuit according to the voltage-current equivalent equation, and calculate the detuning coefficient to obtain the calculated value of the detuning coefficient; Calculate the equivalent input impedance angle of the primary circuit according to the calculated value of the detuning coefficient. The specific process is as follows: Calculate the equivalent input impedance of the primary circuit according to the calculated value of the detuning coefficient and the value of the primary-secondary reflected impedance; Determine the equivalent input impedance angle of the primary circuit according to the equivalent input impedance; Based on the detuning value constraint and the impedance value constraint, drive the ZVS zero-voltage turn-on control according to the equivalent input impedance angle to achieve wireless power transmission control.

2. The wireless power transfer control method with controllable output according to claim 1, characterized in that, The first MOSFET switch and the second MOSFET switch in the primary full-bridge circuit form a primary leading arm; The third MOSFET switch and the fourth MOSFET switch form a primary lagging arm; Control the ZVS zero-voltage turn-on of the MOSFET switches of the primary leading arm and the primary lagging arm by presetting a phase-shift angle.

3. The wireless power transmission control method with controllable output according to claim 1, characterized in that, One end of the primary coil in the LCC-S compensation network is connected in series with one of the primary compensation capacitors and the primary compensation inductor and then connected to the positive end of the midpoint of the primary bridge arm in the primary full-bridge circuit; The other end of the primary coil in the LCC-S compensation network is connected to the negative end of the midpoint of the primary bridge arm in the primary full-bridge circuit.

4. The wireless power transfer control method with controllable output according to claim 1, wherein The secondary full-bridge circuit includes 4 symmetric diodes, and the output terminals are respectively connected in parallel with a filter capacitor and a load; The secondary compensation network includes a receiving coil and a secondary compensation capacitor, and the secondary compensation network is connected to the midpoint of the secondary bridge arm in the secondary full-bridge circuit.

5. The wireless power transmission control method with controllable output according to claim 1, characterized in that, The DSP control circuit generates a PID control instruction according to the current and voltage collected by the sampling circuit; The PID control circuit generates a conduction angle according to the PID control instruction and triggers the PWM drive circuit through the conduction angle to drive the operation of the primary full-bridge circuit.

6. The wireless power transmission control method with controllable output according to claim 1, characterized in that, Introduce the detuning coefficient, perform detuning analysis on the equivalent simplified circuit according to the voltage-current equivalent equation, and calculate the detuning coefficient to obtain the calculated value of the detuning coefficient, including: Introduce the detuning coefficient to perform resonance adjustment on the voltage-current equivalent equation to obtain a resonance equivalent relationship equation; Perform detuning analysis on the equivalent simplified circuit according to the resonance equivalent relationship equation, calculate the detuning coefficient, and obtain the calculated value of the detuning coefficient.

7. The wireless power transmission control method with controllable output according to claim 1, characterized in that, The introduction of the detuning coefficient, performing detuning analysis on the equivalent simplified circuit according to the voltage-current equivalent equation, and calculating the detuning coefficient to obtain the calculated value of the detuning coefficient further includes: Construct an output power expression of the system based on the detuning coefficient; Derive the detuning coefficient according to the output power expression, calculate the detuning coefficient when the partial derivative value is 0, and obtain the reference value of the detuning coefficient.

8. The wireless power transmission control method with controllable output according to claim 1, characterized in that, The implementation of wireless power transfer control by driving ZVS zero-voltage turn-on control based on the detuning value constraint and impedance value constraint according to the equivalent input impedance angle further includes: When the load resistance value changes, introduce a constant current coefficient to calculate the first load output current value, and collect the first load output voltage value. The constant current coefficient is calculated according to the constant current condition; Calculate the constant current phase shift angle of the primary full-bridge circuit according to the first load output current value and the first load output voltage value; Implement constant current control of the primary full-bridge circuit through the PID control circuit according to the constant current phase shift angle.

9. The wireless power transmission control method with controllable output according to claim 1, characterized in that The implementation of wireless power transfer control by driving ZVS zero-voltage turn-on control based on the detuning value constraint and impedance value constraint according to the equivalent input impedance angle further includes: When the load resistance value changes, introduce a constant voltage coefficient to calculate the second load output current value, and collect the second load output voltage value. The constant voltage coefficient is calculated according to the constant voltage condition; Calculate the constant voltage phase shift angle of the primary full-bridge circuit according to the second load output current value and the second load output voltage value; Implement constant voltage control of the primary full-bridge circuit through the PID control circuit according to the constant voltage phase shift angle.

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