CN111682789A - High frequency dual class E inverter system and method for wireless power transfer system - Google Patents

Abstract

The invention relates to a high-frequency double E-type inverter system and method for a wireless power transmission system, and belongs to the field of power electronics technology. While solving the limitations of the traditional wired power transmission method due to the limitation of wires, the dual-class E inverter combined with the new SiC device realizes a high-power inverter with an operating frequency of 1-7.8MHz. Using the combination of DSP and CPLD, a high-frequency pulse and drive controller is designed, which realizes the automatic calibration and tracking of the resonant frequency, and greatly improves the distance, efficiency, power and control of wireless power transmission.

Description

High frequency dual class E inverter system and method for wireless power transfer system

technical field

The present invention relates to the technical field of power electronics, and in particular, to a high-frequency double-E class inverter system and method for a wireless power transmission system.

Background technique

The structure of wireless power transmission is mainly composed of inverter links, transmitting coils, receiving coils, and rectifying links. According to the basic principle of wireless energy transmission, wireless energy transmission can be roughly divided into three types at this stage, namely: electromagnetic wave radiation type, electric field coupling type, and magnetic coupling type. Among them, the magnetic coupling wireless power transmission is further divided into electromagnetic induction and magnetic coupling resonance.

The traditional inverter methods include full-bridge inverter and half-bridge inverter mode, which are very common and the technology is relatively mature. In addition, the power amplifier can also realize the inverter function. Among them, class A, class B, class AB, and class C are called traditional power amplifiers, and class D, class E, and class F are called switching power amplifiers. The direct current is converted into high-frequency alternating current through the inverter, so that the energy of the primary side is transferred to the secondary side to realize wireless power transmission.

Since the resonant frequency of magnetic coupling resonance wireless power transmission is basically above megahertz, half-bridge inverter and full-bridge inverter need to generate multiple PWM waveforms at the same time, and each waveform must also ensure the accuracy of frequency and phase and dead zone. At the same time, because this type of inverter link requires more switching devices, the probability of failure is also greatly increased. Class A amplifiers have excellent linear characteristics, but their theoretical efficiency is only 50%, and the actual efficiency is generally not greater than 25%. When the class B amplifier has no signal input, the amplifier basically consumes no power, and its efficiency can reach 78.5%, but the signal amplitude of the amplifier is in the nonlinear region. The conduction angle of the class C amplifier is usually small, and the maximum efficiency reaches 100%, but the power at this time is zero, so it has no practical significance. Class D power amplifiers have a certain amount of trailing overlap, which will lead to a drop in efficiency. Therefore, class D switches are more suitable for applications where the frequency is lower than MHz, such as digital audio. Class E amplifiers can adjust the switching frequency to achieve soft switching, and the output voltage is a half-sine wave. All in all, all kinds of amplifiers have their own advantages and disadvantages, which cannot meet the magnetic coupling resonant wireless power transmission system with comprehensive power requirements.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a high-frequency double E-type inverter system and method for wireless power transmission system in order to overcome the above-mentioned defects of the prior art.

The object of the present invention can be realized through the following technical solutions:

A high-frequency double-E inverter system for a wireless power transmission system is provided in the wireless power transmission system, the system includes a voltage source V _DC , the positive pole of the voltage source V _DC is respectively connected to the first inductor L ₁ is connected to one end of the _second inductance L2, the other end of the _first inductance L1 is respectively connected to the drain of the first switch tube _Vs1 , one end of the first capacitor C1 and _one end of the resonance unit, the said The other end of the second inductor L ₂ is respectively connected to the drain of the second switch tube V _s2 , one end of the second capacitor C ₂ and the other end of the resonance unit. The first switch tube V _s1 and the The respective sources of the two switches V _s2 and the other ends of the first capacitor C ₁ and the second capacitor C ₂ are all connected to the negative electrode of the voltage source V _DC .

Further, the resonant unit includes a resonant inductor L _r and a resonant capacitor Cr connected in series with each other, a load resistor _R is connected between the resonant inductor L _r and the resonant capacitor _Cr , and the resonant unit passes through the resonant inductor. L _r and the resonant capacitor C _r are respectively connected to the respective drains of the first switch transistor V _s1 and the second switch transistor V _s2 .

Further, the first switch tube V _s1 is a MOSFET switch tube.

Further, the second switch tube V _s2 is a MOSFET switch tube.

Further, the specific switching type of the first switch transistor V _s1 is an enhancement type N-channel MOSFET switch transistor.

Further, the specific switching type of the second switch transistor V _s2 is an enhancement type N-channel MOSFET switch transistor.

The present invention also provides a high-frequency inversion method based on the high-frequency double-E inverter system for a wireless power transmission system, the inversion method specifically includes: the first switch tube V _s1 and the second switch tube V _s2 are alternately turned on at a duty ratio of 50% to supply power to the load resistor R in the resonant unit, and the first inductor L ₁ and the second inductor L ₂ are used to stabilize Input current and make the output current a sine wave, the first capacitor C ₁ and the second capacitor C ₂ and the resonant unit realize soft switching together, the high-frequency double E-class inverter system combined with related devices can make The wireless power transfer system performs power inversion in a specific frequency range.

Further, the related device is a SiC device.

Further, the specific frequency range is from 1MHz to 7.8MHz.

The present invention also provides a frequency modulation method for the high-frequency double-E inverter system used in the wireless power transfer system, the method specifically includes: using a high-speed voltage comparator to obtain the wireless power transfer system The zero-crossing point of the output voltage, input the signal to the CPLD for zero-delay calculation, and then run the closed-loop adjustment through DSP to ensure that the frequency can be infinitely adjusted under the frequency output of the megahertz level, and can track the zero-crossing point. The soft switching of the switching tube and the tracking of the resonant frequency in the high-frequency dual-class E inverter system are described.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention mainly applies the double E-type inverters to the magnetically coupled resonant wireless power transmission system, uses the combination of DSP and CPLD, performs closed-loop control adjustment through DSP, and designs high-frequency pulse and drive control It realizes the automatic calibration and tracking of the resonant frequency, solves the limitations of the traditional wired power transmission method due to the limitation of wires, and greatly improves the distance and efficiency of wireless power transmission. Power stations, electric drones and dynamic wireless charging systems provide very meaningful references and have great application value.

(2) The present invention adopts the principle of magnetic coupling resonance, combined with the advantages of double E-type inverters that can generate high-frequency alternating current and new SiC switching devices with good on-off performance and other advantages, using DSP for closed-loop control, from increasing the resonance frequency. From the perspective of further increasing the transmission power, a wireless power transmission system with longer transmission distance, higher efficiency, better safety, less radiation and easier control is designed.

(3) Compared with the inverter mode in the traditional wireless power transmission, the present invention does not need to generate multiple PWM waveforms at the same time, the dead zone control is convenient, the required switching devices are less, and the function of soft switching can be realized, so it has more advantages. For safety and flexibility, convenient control and other advantages.

At the same time, the present invention designs a high-frequency pulse and drive controller by means of a combination of DSP and CPLD through closed-loop control of the switching frequency of the double-E inverter, realizes automatic calibration and tracking of the resonant frequency, and realizes controllable The high-power inverter can greatly improve wireless energy transmission in terms of distance, efficiency, and power. The application of dual-E inverters to magnetically coupled resonant wireless power transmission has great advantages in terms of distance, efficiency, power, etc. It is the development trend of future power transmission, and it is also a current research hotspot. Its application value is very huge. For the wireless charging of electric vehicles in the future, household power routers have great potential value.

Description of drawings

1 is a schematic diagram of a magnetic coupling resonance wireless power transmission system model of the present invention;

Fig. 2 is the frequency adjustment flow chart in the present invention;

FIG. 3 is a schematic diagram of a class E inverter model in the present invention;

FIG. 4 is a schematic diagram of a double E-class inverter model in the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

The purpose of the invention of the present invention is as follows:

In the prior art, the dual E-type inverters combined with the new SiC devices enable the high-power inverter to operate at a frequency of 1 to 7.8MHz. At the same time, the combination of DSP and CPLD is used to design high-frequency pulse and drive control. It realizes the automatic calibration and tracking of the resonant frequency, so as to realize the magnetic coupling resonant wireless power transmission system with higher efficiency, better safety, less radiation and easy energy control.

The technical principle of the present invention is as follows:

Magnetically coupled resonant wireless power transmission technology is a research hotspot in recent years, and has great application value in future power transmission, electric vehicles and other fields.

The frequency of magnetically coupled resonant wireless power transmission reaches the megahertz level, in which the class E amplifier has a simple structure, easy control, and at the same time, the efficiency can reach 100%. The output power of a single-tube class E power amplifier is limited. This invention designs a dual-class E inverter, the principle of which is the same as that of a single-tube class E inverter. The output waveform of a single class E inverter is half-wave, while the output waveform of double class E inverters combines two class E inverters to form a full-wave output, which increases the output power by 4 times.

At the same time, the invention performs closed-loop control through DSP, and realizes the design of the soft switch of the switch tube and the stepless adjustment of the resonance frequency.

Specific examples:

1. Main idea

The present invention relates to a method for applying double E-type inverters to a magnetically coupled resonant wireless power transmission system, as shown in FIG. 1 . The principle of magnetically coupled resonant wireless power transmission is to use two coils with the same resonant frequency, pass a resonant current to one of the coils, and the other coil will generate a resonant current of the same frequency, thereby realizing energy transmission. A set of magnetic coupling resonance wireless power transmission device, including the design of high frequency inverter, resonant coil, impedance matching, high frequency rectification and other links. One of the key technologies is that the invention uses dual E-type inverters combined with new SiC devices to achieve a high-power inverter with an operating frequency of 1 to 7.8MHz.

As shown in Figure 2, at the same time, the present invention uses a high-speed voltage comparator to obtain the zero-crossing point of the voltage, and inputs the signal to the CPLD. The CPLD combines the signal with the high-frequency pulse to perform closed-loop control and adjustment through the DSP to ensure the frequency output at the megahertz level. It can realize the stepless adjustment of the frequency, and can track the zero-crossing point, realize the soft switching of the switch tube and the tracking of the resonant frequency, so that the wireless power transmission efficiency is higher, the safety is better, the radiation is smaller, and the energy control is easy.

2. Working principle of high frequency inverter of double E inverter

The basic structure of class E amplifier is shown in Figure 3. It has only one switch tube, which is simple in structure and easy to control. When the switch tube is turned on, the power supply charges the inductor. When the switch tube is off, the inductor releases energy and the power supply inductor Power supply to the load together, and through the resonance of the inductor Le and the capacitor Ce, the switching frequency can be adjusted to achieve soft switching. The output voltage of the class E inverter is a half-sine wave, while the double class E inverter uses two identical single class E inverters, and the phases are staggered by 180 degrees, as shown in Figure 4, so that the output waveform is a complete sine. The high-frequency inverter designed in combination with the class E power amplifier has played a very good effect in the magnetically coupled resonant wireless power transmission system.

As shown in FIG. 4 , in this embodiment, the system includes a voltage source V _DC , the positive poles of the voltage source V _DC are connected to one end of the first inductor L ₁ and the second inductor L ₂ respectively, and the other end of the first inductor L ₁ is connected One end is respectively connected with the drain of the first switch tube V _s1 , one end of the first capacitor C ₁ and one end of the resonance unit, and the other end of the second inductor L ₂ is respectively connected with the drain of the second switch tube V _s2 , the second One end of the capacitor C ₂ is connected to the other end of the resonance unit, the respective sources of the first switch tube V _s1 and the second switch tube V _s2 , and the other ends of the first capacitor C ₁ and the second capacitor C ₂ are all connected to the voltage The negative terminal of the source V _DC is connected.

The resonant unit includes a resonant inductance L _r and a resonant capacitor Cr connected in series with each other, the load resistance R is connected between the resonant inductance L _r and the resonant capacitor _Cr , and the resonant unit corresponds to the first through the resonant inductance _{L r} and the resonant capacitor _Cr respectively. The respective drains of the switch tube V _s1 and the second switch tube V _s2 are connected.

Both the first switch tube V _s1 and the second switch tube V _s2 are MOSFET switches, and the corresponding specific switch types are enhancement-mode N-channel MOSFET switches.

The present invention designs a method of applying double E-type inverters to a magnetically coupled resonant wireless power transmission system. Combined with current research hotspots, double E-type inverters are used for high-frequency inversion, and DSP is combined with CPLD. At the same time, the closed-loop control and adjustment of the DSP are used to achieve the matching of the resonance frequency and impedance of the primary and secondary sides, and the maximum efficiency can reach more than 95%. Magnetic coupling resonance wireless power transmission will inevitably play an important role in the future development. status.

The invention mainly applies the high-frequency double-E inverter to the magnetic coupling resonance type wireless power transmission system. Through the closed-loop control of DSP, the design of the soft switch of the switch tube and the stepless adjustment of the resonance frequency are realized. The design has great advantages in both power and efficiency, and the design of its key technologies has a certain advanced nature. It is more practical in application and has great reference significance in related industries.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited to this. Any person skilled in the art can easily think of various equivalents within the technical scope disclosed by the present invention. Modifications or substitutions should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (10)

1. A high-frequency double-E inverter system for a wireless power transmission system is arranged in the wireless power transmission system and is characterized by comprising a voltage source V_DCSaid voltage source V_DCRespectively with the first inductor L₁And a second inductance L₂Is connected to one end of the first inductor L₁The other end of the first switch tube V is respectively connected with the first switch tube V_s1Drain electrode of, first capacitor C₁Is connected to one end of the resonant unit, the second inductance L₂The other end of the first switch tube and the second switch tube V are respectively connected with_s2Drain electrode of the first capacitor C₂Is connected with the other end of the resonance unit, the first switching tube V_s1And the second switch tube V_s2Respective source electrode, the first capacitor C₁And said second capacitance C₂The other ends of the two are connected with the voltage source V_DCAre connected with each other.

2. The high frequency dual class-E inverter system for a wireless power transmission system according to claim 1, wherein the resonant unit includes resonant inductors L connected in series with each other_rAnd a resonance capacitor C_rA load resistor R connected to the resonant inductor L_rAnd a resonance capacitor C_rThe resonant unit passes through the resonant inductor L_rAnd said resonant capacitor C_rAre respectively corresponding to the first switch tube V_s1And the second switch tube V_s2The respective drains are connected.

3. The high-frequency dual class-E inverter system for a wireless power transmission system as claimed in claim 1, wherein the first switching tube V_s1MOSFET switching tubes are adopted.

4. A high frequency dual class E inverter system for a wireless power transfer system according to claim 1,it is characterized in that the second switch tube V_s2MOSFET switching tubes are adopted.

5. The high-frequency dual class-E inverter system for a wireless power transmission system according to claim 1, wherein the first switching tube V_s1Is an enhancement N-channel MOSFET switch tube.

6. The high-frequency dual class-E inverter system for a wireless power transmission system according to claim 1, wherein the second switching tube V_s2Is an enhancement N-channel MOSFET switch tube.

7. The high-frequency inversion method of the high-frequency dual class-E inverter system for the wireless power transmission system according to claim 1, wherein the inversion method specifically comprises: the first switch tube V_s1And the second switch tube V_s2The first inductor L is alternatively conducted to supply power to the load resistor R in the resonance unit at a duty ratio of 50 percent respectively₁And the second inductance L₂The first capacitor C is used for stabilizing the input current and making the output current be sine wave₁And said second capacitance C₂The high-frequency double-E type inverter system can enable the wireless power transmission system to carry out power inversion in a specific frequency range by combining with related devices.

8. The high-frequency inversion method of the high-frequency double class-E inverter system for the wireless power transmission system according to claim 7, wherein the related devices are SiC devices.

9. The high-frequency inversion method of the high-frequency dual class-E inverter system for the wireless power transmission system according to claim 7, wherein the specific frequency range is 1MHz to 7.8 MHz.

10. A frequency modulation method for a high frequency dual class-E inverter system for a wireless power transmission system according to claim 1, the method comprising: and a high-speed voltage comparator is adopted to obtain the zero crossing point of the output voltage of the wireless electric energy transmission system, the signal is input to a CPLD for zero-crossing delay calculation and then is subjected to DSP operation closed loop adjustment to ensure that stepless adjustment of frequency is realized under the frequency output of megahertz level, the zero crossing point can be tracked, and the tracking of the soft switching and the resonant frequency of a switching tube in the high-frequency double-E inverter system is realized.

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