Single tube inverter with full wave output, wireless power transfer system and control method thereof

Abstract

The application relates to the technical field of inverters, and particularly discloses a single-tube inverter with full-wave output, a wireless power transmission system and a control method thereof. The inverter has the characteristics of simple circuit structure, simple driving circuit, only one NMOS tube, resonant state irrelevant to a load, etc. The main switch can be effectively opened at zero voltage from a wide load resistance range from a rated load to a short circuit, the system output voltage is approximately a sine wave, the total harmonic distortion of the system current is very small, and the inverter can be widely applied to various fields of high-frequency inversion. The wireless power transmission system adopts the above inverter at a transmitting end, is coupled to a receiving end through a wireless power transmission coupling mechanism, adopts a series capacitance compensation mode for a compensation network, realizes stable constant voltage output of the system, and effectively realizes zero voltage opening of a power NMOS tube. The system circuit structure is simple, the reactive power is small, the transmission efficiency is high, and the system has the best transmission effect in a wide load resistance range from a rated load to a short circuit.

Description

Technical Field

[0001] This invention relates to the field of inverter technology, and more particularly to a single-tube inverter with full-wave output, a wireless power transmission system using the single-tube inverter with full-wave output, and a control method for the wireless power transmission system. Background Technology

[0002] Inverters can convert input DC power into AC power of a certain frequency. They are widely used in wireless power transmission, high-frequency heating power supplies, home appliances, consumer electronics, electric vehicles, special machinery and medical electronics, and different applications have different requirements for inverters.

[0003] Full-bridge inverters have advantages such as high output power and high transmission efficiency, but their structure has four NMOS transistors, twice that of half-bridge and push-pull circuits, resulting in higher costs and problems such as complex drive circuits and shoot-through of bridge arms.

[0004] Compared to a full-bridge inverter, a half-bridge topology inverter only has two NMOS transistors. However, NMOS transistors are subject to higher voltage and current, resulting in lower power utilization and making them unsuitable for applications with lower operating voltages.

[0005] Like half-bridge inverters, push-pull topology inverters only have two NMOS transistors, which are lower in cost and simpler to drive. However, the voltage stress on NMOS transistors is higher, twice that of full-bridge inverters, and the transformer requires a center tap, resulting in lower transformer winding utilization.

[0006] Single-NMOS inverters have advantages such as simple structure, few NMOS transistors, low cost, convenient driving, and easy zero-voltage turn-on. However, current single-NMOS inverters (such as...) Figure 5 The system exhibits several drawbacks, including high total harmonic distortion (THD) of voltage and current, large input current ripple, and high reactive power. Its output voltage waveform is shown below. Figure 6 (a)V Lp1 The waveform diagram shows the total harmonic distortion (THD) waveform of the system voltage and current. Figure 7 As shown in (a), 8(a), 9(a), and 10(a). Summary of the Invention

[0007] This invention provides a full-wave output single-tube inverter, a wireless power transfer system, and a control method thereof. The technical problems it solves are: how to design a new full-wave output single-tube inverter that can achieve zero-voltage turn-on, low total harmonic distortion (THD) of voltage and current, low input current ripple, and low reactive power in the system, and how to apply this full-wave output single-tube inverter to a wireless power transfer system.

[0008] To solve the above technical problems, the present invention first provides a single-transistor inverter with full-wave output, the key of which is: including a DC power supply V DC Inductor L f Capacitor C f Inductor L p Capacitor C p NMOS transistor Q, PWM signal generator, and inductor L f The capacitor C p The NMOS transistor Q is connected in series with the DC power supply V. DC The positive and negative terminals are connected, and the source terminal of the NMOS transistor Q is connected to the negative terminal of the DC power supply and grounded. The inductor L p Connected in parallel to capacitor C p At both ends, the capacitor C f The source and drain of the NMOS transistor Q are connected in parallel, and the gate of the NMOS transistor Q is connected to the PWM signal generator, which is used to generate a PWM signal with a duty cycle of A.

[0009] Preferably, the inductor L f With the capacitor C f The input resonant angular frequency ω between f satisfy:

[0010] ω f =λω0

[0011] λ∈[1.3,1.5] is the adjustment coefficient, and ω0 is the switching angular frequency of the NMOS transistor Q.

[0012] Preferably, the inductor L p Inductor L used for connection with the receiver s Magnetic coupling is performed, the inductor L f The capacitor C f The inductor L p The capacitor C p The parameters satisfy:

[0013]

[0014] Where ω=ω0 represents the resonant angular frequency of the entire full-wave output single-transistor inverter, R P Indicates the inductance L p The equivalent series resistance, M represents the inductance L. p With the inductor L s Mutual intuition between them, Z s This represents the equivalent impedance of the receiving end.

[0015] Preferably, the position of the NMOS transistor Q is related to the position of the capacitor C.p The positions are swapped, and the inductor L p With the capacitor C f The positions are swapped.

[0016] Preferably, the NMOS transistor Q is an enhancement-mode NMOS transistor; A = 0.5.

[0017] Preferably, the circuit further includes a load resistor R, the load resistor R being connected to the inductor L. p The load resistor R and the inductor L are connected in series. p Connected in parallel to capacitor C p The two ends;

[0018] The inductor L f The capacitor C f The inductor L p The capacitor C p The parameters satisfy:

[0019]

[0020] Where ω=ω0 represents the resonant angular frequency of the entire full-wave output single-transistor inverter, R P Indicates the inductance L p The equivalent series resistance.

[0021] The present invention also provides a wireless power transmission system, including a transmitter and a receiver, the key feature of which is that the transmitter and the receiver respectively adopt the above-mentioned single-tube inverter with full-wave output without load resistor R.

[0022] Preferably, the receiving end includes the inductors L connected in sequence. s Series compensation capacitor C s and load network.

[0023] Preferably, the capacitor C s The parameters satisfy: ω is the resonant angular frequency of the entire system.

[0024] This invention also provides a control method for a wireless power transfer system, the key of which is: inputting a PWM signal with a switching angular frequency ω0 and a duty cycle A to the gate of the NMOS transistor Q, so that the full-wave output single-transistor inverter operates periodically and has the following five operating modes in each switching cycle in chronological order:

[0025] 1) Mode I between t0 and t1: At time t0, the PWM signal is high, and the drain-source voltage V of the NMOS transistor Q is... ds =0, the NMOS transistor Q achieves ZVS conduction, the inductor L f Current Iin The inductor L p Current I Lp Decrease them separately until they cross zero; then, I Lp It begins to increase positively, I in The capacitance C begins to increase in the reverse direction. f Equivalent short circuit, V ds Keep it at zero;

[0026] 2) Mode II between t1 and t2: At time t1, the PWM signal goes low, the NMOS transistor Q is turned off, and the inductor L... f With the capacitor C f The inductor L p With the capacitor C p They begin to resonate separately; then, I Lp Start decreasing in the opposite direction, I in It begins to decrease in the positive direction, V ds It begins to increase positively;

[0027] 3) Mode III between t2 and t3: At time t2, the PWM signal remains low, I Lp I in Decrease them to zero respectively, V ds Reaching the maximum value; then, I Lp It begins to increase positively, I in It starts to increase in the opposite direction, V ds It begins to decrease in a positive direction;

[0028] 4) Mode IV between t3 and t4: At time t3, the PWM signal remains low, I in Reaching the maximum value, I Lp V reaches its minimum value. ds The inductance L drops to zero. f With the capacitor C f The inductor L p With the capacitor C p End resonance; then, I Lp It begins to decrease positively, I in Start decreasing in the opposite direction, V ds Keep it at zero;

[0029] 5) Mode V between t4 and t5: At time t4, the PWM signal goes high, the NMOS transistor Q remains off, and the inductor L... p Continue forward discharge, when I Lp When = 0, enter the next switching cycle repetitive mode I.

[0030] The single-transistor inverter with full-wave output provided by this invention has the characteristics of simple circuit structure, simple control / drive circuit, few NMOS transistors (only one), and easy zero-voltage turn-on. The system voltage is approximately sinusoidal, and the total harmonic distortion (THD) of the system current is very small. Under the same power conditions, the voltage stress is reduced by half compared with the traditional single-transistor resonant inverter, and the reactive power in the system is smaller. This improves the transmission efficiency of the inverter system and can be widely used in various fields of high-frequency inverter.

[0031] The wireless power transmission system provided by this invention uses the above-mentioned full-wave output single-tube inverter at the system transmitter, which effectively realizes zero voltage switch (ZVS) of the power NMOS tube. The system has low reactive power and high transmission efficiency, achieving the best transmission effect over a wide load resistance range from rated load to short circuit.

[0032] The control method for the wireless power transmission system provided by the present invention enables the single-transistor inverter with full-wave output to operate in five different operating modes by inputting a PWM signal with a specific switching angular frequency ω0 and a duty cycle A (0.5) to the gate of the NMOS transistor Q, thereby achieving the best inverter effect. Attached Figure Description

[0033] Figure 1 This is a topology diagram of a single-tube inverter with full-wave output provided in Embodiment 1 of the present invention;

[0034] Figure 2 This is a soft-switching waveform diagram of the NMOS transistor provided in Embodiment 1 of the present invention;

[0035] Figure 3 This is the operating mode diagram of the full-wave output single-tube inverter provided in Embodiment 1 of the present invention; wherein:

[0036] Figure 3 (a) is the circuit transient diagram of mode I;

[0037] Figure 3 (b) is the circuit transient diagram for Mode II;

[0038] Figure 3 (c) is the circuit transient diagram for Mode III;

[0039] Figure 3 (d) is the circuit transient diagram of mode IV;

[0040] Figure 3 (e) is the circuit transient diagram of mode V;

[0041] Figure 4 This is the same as that provided in Embodiment 1 of the present invention. Figure 3 The waveform diagram corresponding to the working mode;

[0042] Figure 5 This is a topology diagram of a conventional Class E single-tube inverter provided in Embodiment 1 of the present invention;

[0043] Figure 6 The conventional Class E single-tube inverter and Class E inverter provided in Embodiment 1 of this invention are... # The waveform diagram of a single-tube inverter; where:

[0044] Figure 6 (a) is the working waveform diagram of a Class E single-tube inverter;

[0045] Figure 6 (b) is E # Operating waveform diagram of a single-tube inverter;

[0046] Figure 7 The conventional Class E single-tube inverter and Class E inverter provided in Embodiment 1 of this invention are... # The FFT decomposition result of the input current waveform of a single-transistor inverter; where:

[0047] Figure 7 (a) is the input current waveform I of a Class E single-transistor inverter. in1 The FFT decomposition results are shown in the figure.

[0048] Figure 7 (b) is E # Input current waveform I of a single-transistor inverter in2 The FFT decomposition results are shown in the figure.

[0049] Figure 8 The conventional Class E single-tube inverter and Class E inverter provided in Embodiment 1 of this invention are... # The FFT decomposition results of the resonant inductor voltage waveform of a single-transistor inverter; where:

[0050] Figure 8 (a) is the resonant inductor voltage waveform V of a Class E single-transistor inverter. Lf1 The FFT decomposition results are shown in the figure.

[0051] Figure 8 (b) is E # The resonant inductor voltage waveform V of a single-transistor inverter Lf2 The FFT decomposition results are shown in the figure.

[0052] Figure 9 The conventional Class E single-tube inverter and Class E inverter provided in Embodiment 1 of this invention are... # The FFT decomposition result of the output winding current waveform of a single-transistor inverter; where:

[0053] Figure 9 (a) is the output winding current waveform I of a Class E single-tube inverter.Lp1 The FFT decomposition results are shown in the figure.

[0054] Figure 9 (b) is E # Output winding current waveform I of a single-tube inverter Lp2 The FFT decomposition results are shown in the figure.

[0055] Figure 10 The conventional Class E single-tube inverter and Class E inverter provided in Embodiment 1 of this invention are... # The FFT decomposition result of the output winding voltage waveform of a single-transistor inverter; where:

[0056] Figure 10 (a) is the output winding voltage waveform V of a Class E single-tube inverter. Lp1 The FFT decomposition results are shown in the figure.

[0057] Figure 10 (b) is E # Output winding voltage waveform V of a single-tube inverter Lp2 The FFT decomposition results are shown in the figure.

[0058] Figure 11 This is a circuit topology diagram of the wireless power transmission system provided in Embodiment 2 of the present invention;

[0059] Figure 12 This is provided in Embodiment 2 of the present invention. Figure 11 Equivalent model diagram;

[0060] Figure 13 This is provided in Embodiment 2 of the present invention when the NMOS transistor Q is turned off. Figure 12 Equivalent model diagram;

[0061] Figure 14 This is a topology diagram of another full-wave output single-tube inverter provided in Embodiment 3 of the present invention;

[0062] Figure 15 This is a circuit topology diagram of another wireless power transmission system provided in Embodiment 4 of the present invention.

[0063] Figure 16 This is a circuit topology diagram of another full-wave output single-tube inverter provided in Embodiment 5 of the present invention;

[0064] Figure 17 This is a circuit topology diagram of another full-wave output single-tube inverter provided in Embodiment 6 of the present invention. Detailed Implementation

[0065] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0066] Example 1

[0067] To design a novel single-MOSFET inverter that achieves full-wave voltage and current output with very low harmonic distortion (THD) and low reactive power in the system under the premise of zero-voltage turn-on of the main switch, and to achieve the best inverter performance over a wide load resistance range from rated load to short circuit, this invention provides a full-wave output single-MOSFET inverter (referred to as single-MOSFET E in this example). # (Inverter-like), its circuit diagram is as follows Figure 1 As shown, it includes a DC power supply V. DC Inductor L f Capacitor C f Inductor L p Capacitor C p NMOS transistor Q, PWM signal generator (not shown), inductor L f Capacitor C p The NMOS transistor Q is connected in series with the DC power supply V. DC The positive and negative terminals are connected, and the source terminal of the NMOS transistor Q is connected to the negative terminal of the DC power supply and grounded, and the inductor L... p Connected in parallel to capacitor C p At both ends, capacitor C f A parallel inductor is connected between the source (S) and drain (D) of the NMOS transistor Q. The gate (G) of the NMOS transistor Q is connected to a PWM signal generator, which generates a PWM signal with a duty cycle of A. Inductor L... f With capacitor C f To form an LC resonant network, the inductor L p With capacitor C p To form an LC compensation network, inductor L p Inductor L used for connection with the receiver s Perform magnetic coupling.

[0068] When DC power is input, a PWM signal is input to the gate (G) of NMOS transistor Q. The main body of the single-transistor inverter, with full-wave output, performs high-frequency inversion of the DC power, and then the power is transmitted through inductor L. p Transmitted to the receiving end, inductor L p With the inductance L at the receiving end sA coupling mechanism is formed, which can output a full-wave sinusoidal high-frequency alternating current. Simultaneously, adjusting the LC resonant parameters of the LC resonant circuit can adjust the soft-switching margin of the NMOS transistor Q, effectively improving the input current waveform and reducing the THD of the input current. To maintain good soft-switching characteristics, the resonant inductor and capacitor L need to be adjusted according to the load conditions and switching frequency. f C f The parameters. Typically, the inductor L... f With the capacitor C f The input resonant angular frequency ω between f The resonant frequency f0 is 1.3-1.5 times the switching angular frequency ω0, meaning the resonant frequency f0 is 2.6-3 times the switching frequency f. That is:

[0069] ω f =λω0 (1)

[0070] λ∈[1.3,1.5] is the adjustment coefficient. In this example, λ=1.5 is taken.

[0071] Based on the above parameters, the voltage waveform across the NMOS transistor is obtained as follows: Figure 2 As shown.

[0072] In one specific and preferred embodiment, the NMOS transistor Q is an enhancement-mode NMOS transistor. The duty cycle of the NMOS transistor Q is set to A = 0.5.

[0073] In order for the circuit to resonate and for the system using this circuit to output a constant voltage, the inductor L f Capacitor C f Inductor L p Capacitor C p The parameters need to be specially designed. The specific design process will be explained in Example 2 when describing the wireless power transmission system, and will not be repeated here.

[0074] Assuming all components in the circuit are ideal, a single transistor E # The operating modes of inverters are as follows Figure 3 As shown, the working waveform is as follows Figure 4 As shown, the specific modal process is as follows:

[0075] 1) Mode I between t0 and t1: At time t0, the PWM signal is high, and the drain-source voltage V of the NMOS transistor Q is... ds =0, NMOS transistor Q achieves ZVS conduction, inductor L f Current I in Inductor L p Current I Lp Decrease them separately until they cross zero; then, I Lp It begins to increase positively, I in The capacitance C begins to increase in the opposite direction.f Equivalent short circuit, V ds Keep it at zero;

[0076] 2) Mode II between t1 and t2: At time t1, the PWM signal goes low, the NMOS transistor Q is turned off, and the inductor L... f With capacitor C f Inductor L p With capacitor C p They begin to resonate separately; then, I Lp Start decreasing in the opposite direction, I in It begins to decrease in the positive direction, V ds It begins to increase positively;

[0077] 3) Mode III between t2 and t3: At time t2, the PWM signal remains low, I Lp I in Decrease them to zero respectively, V ds Reaching the maximum value; then, I Lp It begins to increase positively, I in It starts to increase in the opposite direction, V ds It begins to decrease in a positive direction;

[0078] 4) Mode IV between t3 and t4: At time t3, the PWM signal remains low, I in Reaching the maximum value, I Lp V reaches its minimum value. ds Drop to zero, inductance L f With capacitor C f Inductor L p With capacitor C p End resonance; then, I Lp It begins to decrease positively, I in Start decreasing in the opposite direction, V ds Keep it at zero;

[0079] 5) Mode V between t4 and t5: At time t4, the PWM signal goes high, due to the current flowing through inductor L f The current is still negative, the NMOS transistor Q is still off, and the inductor L... p Continue forward discharge, when I Lp When = 0, enter the next switching cycle repetitive mode I.

[0080] from Figure 4 V ds As can be seen, this circuit effectively achieves the soft-switching (ZVS) turn-on of the NMOS transistor, with current I... in I Lp V Lp All of them are similar to sine waves.

[0081] To better describe the effect of this circuit, the following will use... Figure 5 Taking the traditional fourth-order resonant network E-class single-transistor inverter shown as an example, we compare it with the novel fourth-order resonant network E#-class single-transistor inverter proposed in this invention. From the circuit diagrams, both inverters are fourth-order resonant networks with only one power NMOS transistor, and the number of inductors and capacitors is the same. The main difference lies in the connection method between the inductors, capacitors, and NMOS transistors.

[0082] The following MATLAB / Simulink simulations compare the relevant operating waveforms and total harmonic distortion (THD) of a traditional fourth-order resonant network Class E single-transistor inverter to illustrate the effectiveness of this invention. Both circuits have an input voltage of 25V, series compensation at the receiver, an output power of 20W (10V / 2A), and a switching frequency of 200kHz.

[0083] The operating waveforms of the two single-tube inverters are as follows: Figure 6 (a) and Figure 6 As shown in (b), the parameter with subscript 1 corresponds to the E-type single-tube inverter, and the parameter with subscript 2 corresponds to the E-type inverter of this invention. # Single-tube inverter. (Comparison) Figure 6 (a) and Figure 6 (b) , found:

[0084] From the system input current (I in1 I in2 From the perspective of the two inverter input currents (I), in1 I in2 All of them are similar to sine waves, but the E proposed in this invention is different. # Input current (I) of a single-transistor inverter in2 It is smoother;

[0085] From the voltage waveform across the resonant inductor (V) Lf1 V Lf2 From the perspective of Class E inverter resonant inductor voltage (V) Lf2 The waveform resembles a half-wave, while comparing it with the input current (I) in1 As can be seen from the phase, the reactive power in a Class E inverter system is relatively large. The E inverter proposed in this invention... # Single-transistor inverter resonant inductor voltage (V) Lf2 The waveform resembles a sine wave, while comparing it with the input current (I) in2 As can be seen from the phase, the E proposed in this invention # The reactive power is even lower in single-tube inverters;

[0086] From the output winding current (I Lp1 I Lp2 From the waveform, the output winding currents of both inverters are similar to sine waves;

[0087] From the output winding voltage (V Lp1 V Lp2 From the waveform perspective, the output winding voltages of both types of inverters are similar to sine waves, but the output winding voltage (V) of the E# type single-transistor inverter proposed in this invention is different. Lp2 The surface is smoother, and the voltage assignment is reduced by half, effectively reducing voltage stress.

[0088] From the drain-source voltage waveform (V DS1 V DS2 From this perspective, both inverters effectively achieve the soft-switching (ZVS) turn-on of the NMOS transistor.

[0089] For the two types of single-transistor inverter input current waveforms (I in1 I in2 ), resonant inductor voltage waveform (V) Lf1 V Lf2 ), Output winding current waveform (I) Lp1 I Lp2 ), Output winding voltage waveform (V Lp1 V Lp2 Perform a Fast Fourier Transform (FFT) decomposition to obtain, as follows: Figures 7-10 The diagram shows a comparison of the total harmonic distortion (THD) of the operating waveforms for the two single-tube inverter topologies. A comparison table of total harmonic distortion (THD) is then compiled and presented in Table 1.

[0090] Table 1. Comparison of THD waveforms for two types of single-tube inverters.

[0091]

[0092] Based on the above simulation waveform analysis and total harmonic distortion (THD) analysis of the working waveform, it can be seen that the E proposed in this invention... # Single-tube inverters can reduce the total harmonic distortion (THD) of input current, resonant inductor voltage, output winding current, and output winding voltage, and significantly reduce reactive power in the system.

[0093] In summary, the single-transistor inverter with full-wave output provided by this embodiment of the invention has the characteristics of simple circuit structure, simple control / drive circuit, few NMOS transistors, and easy zero-voltage turn-on. Through the coupling network, it can output full-wave sinusoidal high-frequency AC power, which has the effects of system voltage approximating sinusoidal wave, very small total harmonic distortion (THD) of system current, small input current ripple, and small reactive power, thereby improving the transmission efficiency of inverter system.

[0094] Example 2

[0095] Based on Embodiment 1, this embodiment of the invention provides a wireless power transmission system, such as... Figure 11 As shown, the system includes a transmitter and a receiver. The transmitter uses a full-wave output single-tube inverter (i.e., E) proposed in Example 1. # (Similar to a single-tube inverter). The receiving end includes inductors L connected in sequence. s The system employs a series compensation capacitor Cs network and a load network. When DC power is input, a single NMOS transistor main circuit driven by a PWM signal first performs high-frequency inversion of the DC power. This DC power is then coupled to the receiving end compensation network via a wireless power transfer coupling mechanism, and a series capacitor compensation method is used. This allows the system to maintain ZVS and a constant voltage amplitude output over a wide load resistance range from rated load to short circuit. This system achieves constant current or constant voltage output without changing the driving PWM signal frequency or duty cycle, simplifying the control method.

[0096] To simplify the analysis, this invention uses the PS inductive coupling model as an example to analyze E. # The parameters of the compensation network for an inductively coupled model of a high-frequency resonant inverter are derived. Figure 4 The waveform diagram shows the compensation capacitor C of the transmitting coil. p The waveforms at both ends are similar to sine waves. For ease of calculation, the model makes the following assumptions: assuming C... p The voltage across the terminals is a standard sine wave. The equivalent model of PS inductive coupling mutual inductance is as follows: Figure 12 As shown.

[0097] The expression for the input impedance of the series-compensated receiver is:

[0098]

[0099] Where R s Indicating inductance L s The equivalent series resistance, R L ω represents the equivalent series resistance of the load network, and ω = ω0 represents the resonant angular frequency of the entire full-wave output single-tube inverter or the entire wireless power transmission system.

[0100] To meet the inverter's maximum power output requirement, the secondary side should be resistive, satisfying the following:

[0101]

[0102] Therefore, the equivalent impedance of the secondary side is:

[0103] Z s =R L +R s (4)

[0104] Define the reflection impedance as:

[0105]

[0106] M represents inductance L p With inductor L s Mutual attraction between them.

[0107] The expression for the input impedance of the PS-coupled network is:

[0108]

[0109] R p Indicating inductance L p The equivalent series resistance.

[0110] When NMOS transistor Q is turned off, E # The inductive coupling model of a single-tube inverter with near-full-wave output is as follows: Figure 13 As shown.

[0111] The expression for the input impedance is:

[0112]

[0113] in:

[0114]

[0115] For the system's equivalent input impedance to be purely resistive, the following must be satisfied:

[0116]

[0117] Therefore, we can conclude that E # The condition for full reactive power compensation in a single-transistor inverter-coupled circuit system is:

[0118]

[0119] The resonant capacitor C is obtained. f Primary-side compensation capacitor C p Secondary side compensation capacitor C s The expressions are as follows:

[0120]

[0121] The simulation of this system is similar to that in Example 1, and will not be described again here.

[0122] This embodiment also provides a control method for a wireless power transmission system, including:

[0123] A PWM signal with a switching angular frequency ω0 and a duty cycle A (0.5) is input to the gate (G) of the NMOS transistor Q, causing the single-transistor inverter with full-wave output to operate periodically and, in each switching cycle, exist sequentially as described above. Figure 4 The five operating modes are shown.

[0124] The wireless power transmission system provided in this embodiment of the invention uses a single-tube inverter with full-wave output as described above at the transmitting end. It is coupled to the compensation network at the receiving end through a wireless power transmission coupling mechanism and uses a series capacitor compensation method to achieve stable constant voltage output of the system. It effectively realizes zero voltage switch (ZVS) of the power NMOS tube, the system has low reactive power, high transmission efficiency, and achieves the best transmission effect over a wide load resistance range from rated load to short circuit.

[0125] The control method for the wireless power transmission system provided in this invention achieves the best inverter effect by inputting a PWM signal with a specific switching angular frequency ω0 and a duty cycle A (0.5) to the gate of the NMOS transistor Q, thereby enabling the full-wave output single-transistor inverter to operate in five different operating modes.

[0126] Example 3

[0127] This embodiment provides another type of full-wave output single-tube inverter, such as... Figure 14 As shown, the difference between it and the full-wave output single-transistor inverter provided in Example 1 lies in the position of the NMOS transistor Q and the capacitor C. p The positions have been swapped, inductor L p With capacitor C f The positions have been swapped. The difference between these two circuits lies in their driving methods; Example 1 uses direct driving, while this example uses floating ground driving. Both circuits can achieve the same effect.

[0128] Example 4

[0129] This embodiment provides another wireless power transmission system, such as Figure 15 As shown, the difference between it and the wireless power transmission system provided in Embodiment 2 is that the transmitter uses a single-tube inverter with full-wave output provided in Embodiment 3. The two systems can achieve the same effect.

[0130] Example 5

[0131] This embodiment provides another full-wave output single-tube inverter, which differs from the full-wave output single-tube inverter provided in Embodiment 1 in that the inverter in this embodiment is used for other inverter scenarios, such as... Figure 16 As shown, in this example, the inverter acts directly on the AC load without any subsequent circuitry. This load is represented by the load resistance R. It can be seen that the load resistance R and the inductance L... p A series connection between the load resistor R and the inductor L. p Connected in parallel to capacitor C p The two ends.

[0132] Similarly, the inverter must satisfy equation (1), and the NMOS transistor Q must be an enhancement-mode NMOS transistor with A = 0.5. Based on the resonance relationship, the inductor L... f Capacitor C f Inductor L p Capacitor C p The parameters satisfy:

[0133]

[0134] Where ω=ω0 represents the resonant angular frequency of the entire full-wave output single-transistor inverter, R P Indicating inductance L p The equivalent series resistance.

[0135] Example 6

[0136] This embodiment provides another type of full-wave output single-tube inverter, such as... Figure 17 As shown, the difference between it and the full-wave output single-transistor inverter provided in Example 5 lies in the position of the NMOS transistor Q and the capacitor C. p The positions have been swapped, inductor L p With capacitor C f The positions have been swapped. The difference between these two circuits lies in their driving methods; Example 5 uses floating ground driving, while this example uses direct driving. Both circuits can achieve the same effect.

[0137] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A control method for a wireless power transmission system, the wireless power transmission system comprising a transmitter and a receiver, the transmitter employing a full-wave output single-tube inverter, the single-tube inverter comprising a DC power supply V DC Inductor L f Capacitor C f Inductor L p Capacitor C p NMOS transistor Q, PWM signal generator, and inductor L f The capacitor C p The NMOS transistor Q is connected in series with the DC power supply V. DC The positive and negative terminals are connected, and the source terminal of the NMOS transistor Q is connected to the negative terminal of the DC power supply and grounded. The inductor L p Connected in parallel to capacitor C p At both ends, the capacitor C f A parallel connection is made between the source (S) and drain (D) terminals of the NMOS transistor Q, and the gate (G) terminal of the NMOS transistor Q is connected to the PWM signal generator, which is used to generate a PWM signal with a duty cycle of A; characterized in that, The control method includes: The PWM signal, which sets the switching angular frequency ω0 and duty cycle A of the NMOS transistor Q, is input to the gate (G) of the NMOS transistor Q, causing the full-wave output single-transistor inverter to operate periodically and exhibit the following five operating modes sequentially in each switching cycle: 1) Modes between t0 and t1 At time t0, the PWM signal is high, and the drain-source voltage V of the NMOS transistor Q is... ds =0, the NMOS transistor Q achieves ZVS conduction, the inductor L f Current I in The inductor L p Current I Lp Decrease them separately until they cross zero; then, I Lp It begins to increase positively, I in The capacitance C begins to increase in the reverse direction. f Equivalent short circuit, V ds Keep it at zero; 2) Modes between t1 and t2 At time t1, the PWM signal goes low, the NMOS transistor Q is turned off, and the inductor L... f With the capacitor C f The inductor L p With the capacitor C p They begin to resonate separately; then, I Lp Start decreasing in the opposite direction, I in It begins to decrease in the positive direction, V ds It begins to increase positively; 3) Modes between t2 and t3 At time t2, the PWM signal remains low, I Lp I in Decrease them to zero respectively, V ds Reaching the maximum value; then, I Lp It begins to increase positively, I in It starts to increase in the opposite direction, V ds It begins to decrease in a positive direction; 4) Modes between t3 and t4 At time t3, the PWM signal remains low, I in Reaching the maximum value, I Lp V reaches its minimum value. ds The inductance L drops to zero. f With the capacitor C f The inductor L p With the capacitor C p End resonance; then, I Lp It begins to decrease positively, I in Start decreasing in the opposite direction, V ds Keep it at zero; 5) Modes between t4 and t5 At time t4, the PWM signal goes high, the NMOS transistor Q remains off, and the inductor L... p Continue forward discharge, when I Lp When =0, enter the repetitive mode of the next switching cycle. .

2. The control method for the wireless power transmission system according to claim 1, characterized in that: The inductor L f With the capacitor C f The input resonant angular frequency between f satisfy , ∈[1.3,1.5] is the adjustment coefficient; the inductance L p Inductor L used for connection with the receiver s Magnetic coupling is performed, the inductor L f The capacitor C f The inductor L p The capacitor C p The parameters satisfy: ， Where ω=ω0 represents the resonant angular frequency of the entire full-wave output single-transistor inverter, R P Indicates the inductance L p The equivalent series resistance. Indicates the inductance L p With the inductor L s Mutual intuition between them This represents the equivalent impedance of the receiving end.

3. The control method for the wireless power transmission system according to claim 1, characterized in that: The position of the NMOS transistor Q and the capacitor C p The positions are swapped, and the inductor L p With the capacitor C f The positions are swapped.

4. The control method for the wireless power transmission system according to claim 1, characterized in that: The NMOS transistor Q is an enhancement-mode NMOS transistor; A=0.

5.

5. The control method for the wireless power transmission system according to any one of claims 1 to 4, characterized in that: The wireless power transfer system also includes a load resistor R, which is connected to the inductor L. p The load resistor R and the inductor L are connected in series. p Connected in parallel to capacitor C p The two ends; The inductor L f The capacitor C f The inductor L p The capacitor C p The parameters satisfy: ， Where ω=ω0 represents the resonant angular frequency of the entire full-wave output single-transistor inverter, R P Indicates the inductance L p The equivalent series resistance.

6. The control method for the wireless power transmission system according to claim 5, characterized in that: The receiving end includes the inductors L connected in sequence. s Series compensation capacitor C s and load network.

7. The control method for the wireless power transmission system according to claim 6, characterized in that, The capacitor C s The parameters satisfy: ω represents the resonant angular frequency of the entire wireless power transmission system.

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