Dual-Buck Dead-Time-Free Magnetic Coupling Wireless Charging Device

Abstract

A magnetic coupling wireless charging device based on double buck without dead zone belongs to the field of wireless charging technology. It solves the problem that in traditional wireless charging devices, a dead time is added and all the power switching tubes in the same group are in the off state. In this off state, the inverter in the wireless charging device cannot output voltage, resulting in incomplete output voltage and poor reliability of the wireless charging device. The present invention includes a double buck without dead zone full bridge inverter circuit, a filter circuit, a coupling coil M, an H-bridge rectifier circuit and an LC circuit; the double buck without dead zone full bridge inverter circuit is composed of two parallel-connected half-bridge inverter circuits. The present invention adopts a double buck structure in which a power tube and a diode connected in anti-parallel are in series in the same bridge arm, thus avoiding the problem of mis-conduction in the same bridge arm and ensuring complete output voltage and current. The present invention is mainly applied to the wireless charging field in such special application scenarios as medical treatment, underwater navigation, aerospace, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless charging. Background Art

[0002] Wireless transmission methods using electromagnetic effects can be divided into two types: near-field or far-field transmission. Far-field transmission generally uses electromagnetic radiation and laser for long-distance transmission, while near-field transmission is generally divided into two methods: electric field or magnetic field coupling. Electric field coupling realizes power transmission through coupling plates. This method has a relatively simple structure, but the equipment required is relatively large in volume and the transmission power is small, so there are not many applicable occasions. Magnetic field coupling can be divided into inductive coupling and resonant coupling. The working principles of these two methods are roughly the same, both using coupling coils to transfer energy. The difference is that the primary and secondary side coil parameters of resonant coupling are the same, and the primary and secondary sides are in a resonant state during operation, which is beneficial to improving the power efficiency. However, this method has relatively high requirements for the resonance frequency and placement position of the coupling coils, and the structure is more complex than that of inductive coupling, so it is not as widely used as inductive coupling. Figure 1 It is the circuit topology structure of traditional inductive coupling wireless charging technology.

[0003] For various near-field transmission structures, the direct current on the primary side has to go through an inversion link to output alternating current and then be transmitted externally through a coupling element. However, in the working process of the bridge-type inversion circuit, the upper and lower power tubes on the same bridge arm may conduct directly, causing a short circuit. In order to avoid this problem, a dead time needs to be added to the complementary drive signals of the same group of MOS tubes. During this period of time, the power switching tubes in the same group are all in the off state, and the inversion current flows through the diode for freewheeling. The appearance of this blind area usually affects the working reliability of the system, increases energy loss, and weakens the power quality. Moreover, when the proportion of the dead time in the working cycle becomes larger and larger, it may also cause voltage distortion and even damage the device.

[0004] However, when wireless charging technology is applied in places with high requirements for power quality and power supply reliability, such as "artificial hearts" in the medical field, or microchips such as cardiac pacemakers implanted in the human body; or when charging deep-sea submersibles in the underwater navigation field; or when charging extravehicular devices in aerospace, etc. In special cases where a system requiring long-term stable power supply needs to be charged. In these cases, once the inverter bridge arm of the wireless transmission device is mis-conducted, it will seriously affect the reliability of the system. At this time, the traditional wireless charging device cannot meet the requirements in this working environment. Therefore, in this case, very high requirements are put forward for the reliability of the wireless charging device. The traditional wireless charging device has an incomplete output voltage and poor reliability and cannot meet this requirement, so the above problems need to be solved urgently. Summary of the Invention

[0005] The object of the present invention is to add a dead time to a traditional wireless charging device. In this state where all the power switching tubes in the same group are turned off, the inverter in the wireless charging device cannot output a voltage, resulting in problems such as incomplete output voltage and poor reliability of the wireless charging device. The present invention provides a magnetic coupling wireless charging device based on double buck without dead time.

[0006] The magnetic coupling wireless charging device based on double buck without dead time includes a double buck without dead time full-bridge inverter circuit, a filter circuit, a coupling coil M, an H-bridge rectifier circuit, and an LC circuit;

[0007] The double buck without dead time full-bridge inverter circuit is composed of two parallel-connected half-bridge inverter circuits, which are used to convert the input DC power supply U i into alternating current, and after filtering the alternating current through the filter circuit, it is coupled to the H-bridge rectifier circuit through the coupling coil M. After the H-bridge rectifier circuit rectifies the received filtered alternating current, the output direct current is filtered through the LC circuit and then supplies power to the load;

[0008] The double buck without dead time full-bridge inverter circuit includes power switching tubes S1 to S4, and diodes D1 to D4; among them, power switching tube S1, power switching tube S3, diode D1, and diode D3 form the first half-bridge inverter circuit, and power switching tube S2, power switching tube S4, diode D2, and diode D4 form the second half-bridge inverter circuit;

[0009] The drain of power switching tube S1, the drain of power switching tube S2, the cathode of diode D3, and the cathode of diode D4 are simultaneously connected to the positive pole of the DC power supply U i ;

[0010] After the source of power switching tube S1 is connected to the cathode of diode D1, it is used as an AC output terminal of the first half-bridge inverter circuit and is connected to the filter circuit;

[0011] After the anode of diode D3 is connected to the drain of power switching tube S3, it is used as another AC output terminal of the first half-bridge inverter circuit and is connected to the filter circuit;

[0012] The anode of diode D1, the source of power switching tube S3, the anode of diode D2, and the source of power switching tube S4 are simultaneously connected to the negative pole of the DC power supply U i ; After the source of power switching tube S2 and the cathode of diode D2 are simultaneously connected, it is used as an AC output terminal of the second half-bridge inverter circuit and is connected to the filter circuit;

[0013] After the anode of diode D4 is connected to the drain of power switching tube S4, it is used as another AC output terminal of the second half-bridge inverter circuit and is connected to the filter circuit.

[0014] Preferably, the filter circuit includes inductors L1 to L4 and capacitor C1;

[0015] One end of inductor L1 is connected to the source electrode of power switch S1, one end of inductor L3 is connected to the anode of diode D3, and the other end of inductor L1 is connected to the other end of inductor L3, one end of capacitor C1 and the same-named terminal of the primary winding of coupling coil M simultaneously;

[0016] One end of inductor L2 is connected to the source electrode of power switch S2, one end of inductor L4 is connected to the anode of diode D4, and the other end of inductor L2 is connected to the other end of inductor L4, the other end of capacitor C1 and the different-named terminal of the primary winding of coupling coil M simultaneously;

[0017] The same-named terminal and different-named terminal of the secondary winding of coupling coil M are respectively connected to the two AC input terminals of the H-bridge rectifier circuit simultaneously.

[0018] Preferably, the H-bridge rectifier circuit includes diodes D5, D6, D7 and D8;

[0019] After the anode of diode D5 and the cathode of diode D6 are connected, it serves as the first AC input terminal of the H-bridge rectifier circuit;

[0020] After the anode of diode D7 and the cathode of diode D8 are connected, it serves as the second AC input terminal of the H-bridge rectifier circuit;

[0021] After the cathode of diode D5 and the cathode of diode D7 are connected, it serves as the positive output terminal of the H-bridge rectifier circuit;

[0022] After the cathode of diode D6 and the cathode of diode D8 are connected, it serves as the negative output terminal of the H-bridge rectifier circuit.

[0023] Preferably, the LC circuit includes inductor L5 and capacitor C2;

[0024] The positive output terminal of the H-bridge rectifier circuit is connected to one end of inductor L5, and the other end of inductor L5 is connected to one end of capacitor C2 and then serves as the positive output terminal of the charging device and is connected to one end of the load;

[0025] The negative output terminal of the H-bridge rectifier circuit is connected to the other end of capacitor C2 and then serves as the negative output terminal of the charging device and is connected to the other end of the load.

[0026] Preferably, inductors L1 and L3 form a pair of forward-coupled inductors, and one end of inductor L1 and one end of inductor L3 both serve as the same-named terminals of a pair of forward-coupled inductors, and the other end of inductor L1 and the other end of inductor L3 both serve as the different-named terminals of a pair of forward-coupled inductors;

[0027] Inductor L2 and inductor L4 form another pair of forward-coupled inductors. One end of inductor L2 and one end of inductor L4 are both used as the like-named ends of the other pair of forward-coupled inductors, and the other end of inductor L2 and the other end of inductor L4 are both used as the unlike-named ends of the other pair of forward-coupled inductors.

[0028] Preferably, inductor L1 and inductor L3 form a pair of backward-coupled inductors. The other end of inductor L1 and one end of inductor L3 are both used as the like-named ends of the pair of backward-coupled inductors, and one end of inductor L1 and the other end of inductor L3 are both used as the unlike-named ends of the pair of backward-coupled inductors;

[0029] Inductor L2 and inductor L4 form another pair of backward-coupled inductors. The other end of inductor L2 and one end of inductor L4 are both used as the like-named ends of the other pair of backward-coupled inductors, and one end of inductor L2 and the other end of inductor L4 are both used as the unlike-named ends of the other pair of backward-coupled inductors.

[0030] Preferably, the double-buck dead-time-free magnetic coupling wireless charging device further includes a soft-switching branch;

[0031] The soft-switching branch includes IGBT transistor S 11 、IGBT transistor S 21 、inductor L' r1 、inductor L' r2 、inductor L r1 、inductor L r2 、capacitor C r1 、capacitor C r2 、diode D r1 、diode D r2 、diode D s1 and diode D s2 ;

[0032] The collector of IGBT transistor S 21 is connected to the anode of diode D3. The emitter of IGBT transistor S 21 is connected to one end of inductor L r2 . The other end of inductor L r2 is simultaneously connected to one end of inductor L' r2 and one end of capacitor C r2 . The other end of inductor L' r2 is connected to the anode of diode D r2 . The cathode of diode D r2 is connected to the other end of capacitor C r2 and the anode of diode D s2 simultaneously. The cathode of diode D s2 is connected to the cathode of diode D2;

[0033] IGBT transistor S 21The collector of is connected to the anode of diode D3, and the emitter of IGBT transistor S 21 is connected to one end of inductor L r2 One end of inductor L r2 The other end is connected to one end of inductor L' r2 One end of inductor L' r2 And one end of capacitor C are connected simultaneously. The other end of inductor L' r2 Is connected to the anode of diode D r2 The anode of diode D r2 The cathode is connected to the other end of capacitor C r2 And the anode of diode D s2 Are connected simultaneously. The cathode of diode D s2 Is connected to the cathode of diode D2;

[0034] The collector of IGBT transistor S 11 Is connected to the anode of diode D4, and the emitter of IGBT transistor S 11 Is connected to one end of inductor L r1 One end of inductor L r1 The other end is connected to one end of inductor L' r1 One end of inductor L' r1 And one end of capacitor C are connected simultaneously. The other end of inductor L' r1 Is connected to the anode of diode D r1 The anode of diode D r1 The cathode is connected to the other end of capacitor C r1 And the anode of diode D s1 Are connected simultaneously. The cathode of diode D s1 Is connected to the cathode of diode D1.

[0035] Preferably, power switch transistors S1 to S4 are all N-type MOSFET transistors.

[0036] Preferably, Wherein,

[0037] The i sum1 Is the sum of the current i Lf1 Flowing through inductor L1 and the current i Lf3 Flowing through inductor L3. i bias1 Is the bias current applied to inductors L1 and L3. i sum2 Is the current i Lf2 Flowing through inductor L2 and the current i Lf4 Flowing through inductor L4. i bias2 Is the bias current applied to inductors L2 and L4. i th1 Is the first offset current. i th2 Is the second offset current.

[0038] The beneficial effects brought by the present invention are as follows:

[0039] The magnetic coupling wireless charging device based on double buck without dead zone provided by the present invention consists of a power supply, a double buck full-bridge inverter circuit without dead zone, a coupling coil M, an H-bridge rectifier circuit, an LC filter link, and an external load. The primary side of the wireless charging device controls the switching devices by using the PWM pulse width modulation method, and the H-bridge rectifier circuit on the secondary side is composed of diodes without the need to add a control link. The present invention adopts a double buck structure in which a power tube and a diode in reverse parallel are connected in series in the same bridge arm, thus avoiding the problem of mis-conduction in the same bridge arm and making the output voltage and current complete. There is no need to add dead time either, greatly improving the reliability of power transmission. Based on the structure of the wireless charging device described in the present invention, the inductor current can be ensured to be continuous, avoiding the distortion of the output current caused by the discontinuous inductor current.

[0040] In the present invention, the forward coupling and reverse coupling methods of inductors are also adopted to reduce the overall volume and weight of the system. Specifically, two inductors are wound on the same iron core for forward coupling or reverse coupling to reduce the overall volume and weight of the system. The present invention also adopts a soft-switching branch to reduce the on and off losses of the switching devices and improve the efficiency of the system.

[0041] The magnetic coupling wireless charging device based on double buck without dead zone provided by the present invention solves the problem of low reliability of traditional inductive wireless charging devices, improves the reliability of the device during the transmission process, and meets the wireless charging requirements in such special application scenarios as medical treatment, underwater navigation, aerospace, etc. In addition, the initial scheme is optimized by means of magnetic integration and soft switching, improving the system performance. Brief Description of the Drawings

[0042] Figure 1 is a schematic diagram of the principle of the topological structure of a traditional electromagnetic induction wireless charging circuit;

[0043] Figure 2 is a schematic diagram of the principle of the magnetic coupling wireless charging device based on double buck without dead zone described in the present invention;

[0044] Figure 3 is a schematic diagram of the principle of a pair of forward-coupled inductors composed of inductor L1 and inductor L3;

[0045] Figure 4 is a schematic diagram of the principle of the magnetic coupling wireless charging device based on double buck without dead zone with forward-coupled inductors;

[0046] Figure 5 is a schematic diagram of the principle of a pair of reverse-coupled inductors composed of inductor L1 and inductor L3;

[0047] Figure 6It is a schematic diagram of the principle of a magnetic coupling wireless charging device based on dual buck without dead zone with reverse coupling inductance;

[0048] Figure 7 It is a schematic diagram of the principle of a magnetic coupling wireless charging device based on dual buck without dead zone of the soft switch branch;

[0049] Figure 8 It is a schematic diagram of the principle of the primary side circuit of the magnetic coupling wireless charging device based on dual buck without dead zone of the present invention; wherein, i Lf1 , i Lf2 , i Lf3 and i Lf4 are the currents flowing through inductors L1 to L4 respectively;

[0050] Figure 9 It is a relationship diagram of the influence of the continuous and discontinuous current flowing through inductor L1 on the voltage between the source and drain of power switch tube S1; wherein, Figure 9 a is the voltage relationship diagram between the source and drain of power switch tube S1 corresponding to when the current i Lf1 flowing through inductor L1 is continuous; Figure 9 b is the voltage relationship diagram between the source and drain of power switch tube S1 corresponding to when the current i Lf1 flowing through inductor L1 is discontinuous; the i Lf1 , i Lf2 , i Lf3 and i Lf4 are the currents flowing through inductors L1 to L4 respectively; V DS-S1 is the voltage between the source and drain of power switch tube S1, V O is the voltage between the source and drain of power switch tube S1 when it is turned off, T S is the switching period, t d is the time node when the current i Lf1 is discontinuous, t s is the time, △i Lf1 is the current ripple of inductor L1. Specific embodiments

[0051] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0052] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0053] Specific Embodiment 1: Refer to Figure 2 This embodiment will be described. The magnetically coupled wireless charging device based on dual buck zero - dead - zone includes a dual buck zero - dead - zone full - bridge inverter circuit, a filter circuit, a coupling coil M, an H - bridge rectifier circuit, and an LC circuit;

[0054] The dual buck zero - dead - zone full - bridge inverter circuit is composed of two paralleled half - bridge inverter circuits, which are used to convert the input DC power supply U i into alternating current. After filtering the alternating current through the filter circuit, it is coupled to the H - bridge rectifier circuit through the coupling coil M. After rectifying the filtered alternating current received by the H - bridge rectifier circuit, the output direct current is filtered through the LC circuit to supply power to the load;

[0055] The dual buck zero - dead - zone full - bridge inverter circuit includes power switch tubes S1 to S4, and diodes D1 to D4; among them, power switch tubes S1, S3, diode D1, and diode D3 form the first half - bridge inverter circuit, and power switch tubes S2, S4, diode D2, and diode D4 form the second half - bridge inverter circuit;

[0056] The drain of power switch tube S1, the drain of power switch tube S2, the cathode of diode D3, and the cathode of diode D4 are simultaneously connected to the positive electrode of the DC power supply U i ;

[0057] After the source of power switch tube S1 is connected to the cathode of diode D1, it is used as an AC output terminal of the first half - bridge inverter circuit to access the filter circuit;

[0058] After the anode of diode D3 is connected to the drain of power switch tube S3, it is used as another AC output terminal of the first half - bridge inverter circuit to access the filter circuit;

[0059] The anode of diode D1, the source of power switch tube S3, the anode of diode D2, and the source of power switch tube S4 are simultaneously connected to the negative electrode of the DC power supply U i ; After the source of power switch tube S2 and the cathode of diode D2 are simultaneously connected, it is used as an AC output terminal of the second half - bridge inverter circuit to access the filter circuit;

[0060] After the anode of diode D4 is connected to the drain of power switch tube S4, it is used as another AC output terminal of the second half - bridge inverter circuit to access the filter circuit. During application, power switch tubes S1 to S4 can all adopt N - type MOSFET tubes.

[0061] The magnetic coupling wireless charging device based on double buck without dead zone provided by the present invention consists of a power supply, a double buck without dead zone full-bridge inverter circuit, a coupling coil M, an H-bridge rectifier circuit, an LC loop filtering link, and an external load. The primary side of the wireless charging device controls the switching devices by using the PWM pulse width modulation method, and the H-bridge rectifier circuit on the secondary side is composed of diodes and does not require adding a control link. The present invention adopts a double buck structure in which a power tube and a diode connected in reverse parallel are in series in the same bridge arm, thus avoiding the problem of mis-conduction in the same bridge arm and eliminating the need to add dead time, greatly improving the reliability of power transmission.

[0062] In order to ensure continuous inductor current and avoid output current distortion caused by discontinuous inductor current in the present invention, in specific applications, wherein, The i sum1 is the sum of the current i Lf1 flowing through inductor L1 and the current i Lf3 flowing through inductor L3, i bias1 is the bias current added to inductors L1 and L3, i sum2 is the sum of the current i Lf2 flowing through inductor L2 and the current i Lf4 flowing through inductor L4, i bias2 is the bias current added to inductors L2 and L4, i th1 is the first offset current, which is the offset current applied to prevent discontinuous current in L1 and L3, i th2 is the second offset current, which is the offset current applied to prevent discontinuous current in L2 and L4. Refer to Figure 2 , further, a specific structure is provided for the filtering circuit: the filtering circuit includes inductors L1 to L4 and a capacitor C1; one end of inductor L1 is connected to the source electrode of power switch tube S1, one end of inductor L3 is connected to the anode of diode D3, and the other end of inductor L1 is simultaneously connected to the other end of inductor L3, one end of capacitor C1, and the same-name end of the primary winding of coupling coil M; one end of inductor L2 is connected to the source electrode of power switch tube S2, one end of inductor L4 is connected to the anode of diode D4, and the other end of inductor L2 is simultaneously connected to the other end of inductor L4, the other end of capacitor C1, and the different-name end of the primary winding of coupling coil M; the same-name end and different-name end of the secondary winding of coupling coil M are respectively connected to the two AC input terminals of the H-bridge rectifier circuit.

[0063] Refer to Figure 2 , further, the specific structure of the H-bridge rectifier circuit is: the H-bridge rectifier circuit includes diodes D5, D6, D7, and D8;

[0064] After the anode of diode D5 and the cathode of diode D6 are connected, they serve as the first AC input terminal of the H-bridge rectifier circuit;

[0065] After the anode of diode D7 and the cathode of diode D8 are connected, they serve as the second AC input terminal of the H-bridge rectifier circuit;

[0066] After the cathodes of diode D5 and diode D7 are connected, they serve as the positive output terminal of the H-bridge rectifier circuit;

[0067] After the cathodes of diode D6 and diode D8 are connected, they serve as the negative output terminal of the H-bridge rectifier circuit.

[0068] See Figure 2 , the specific structure of the LC circuit is: the LC circuit includes an inductor L5 and a capacitor C2;

[0069] The positive output terminal of the H-bridge rectifier circuit is connected to one end of the inductor L5, and the other end of the inductor L5 is connected to one end of the capacitor C2 and then serves as the positive output terminal of the charging device and is connected to one end of the load;

[0070] The negative output terminal of the H-bridge rectifier circuit is connected to the other end of the capacitor C2 and then serves as the negative output terminal of the charging device and is connected to the other end of the load.

[0071] See Figure 3 and Figure 4 , further, by positively coupling inductor L1 and inductor L3, and positively coupling inductor L2 and inductor L4, the inductor L1 and inductor L3 are wound on the same iron core for positive coupling, and the inductor L2 and inductor L4 are wound on the same iron core for positive coupling, reducing the overall volume and weight of the wireless charging device of the present invention. Specifically: inductor L1 and inductor L3 form a pair of positively coupled inductors, and one end of inductor L1 and one end of inductor L3 both serve as the same-named ends of a pair of positively coupled inductors, and the other end of inductor L1 and the other end of inductor L3 both serve as the different-named ends of a pair of positively coupled inductors; inductor L2 and inductor L4 form another pair of positively coupled inductors, and one end of inductor L2 and one end of inductor L4 both serve as the same-named ends of another pair of positively coupled inductors, and the other end of inductor L2 and the other end of inductor L4 both serve as the different-named ends of another pair of positively coupled inductors. In this preferred embodiment, the positive coupling method increases the equivalent inductance in the circuit, which is beneficial to reducing the current ripple in the inductor circuit.

[0072] See Figure 5 and Figure 6, Further, by reversely coupling inductor L1 and inductor L3, and reversely coupling inductor L2 and inductor L4, inductor L1 and inductor L3 are wound on the same iron core for reverse coupling, and inductor L2 and inductor L4 are wound on the same iron core for reverse coupling, reducing the overall volume and weight of the wireless charging device of the present invention. Specifically: Inductor L1 and inductor L3 form a pair of reversely coupled inductors, and one end of inductor L1 and one end of inductor L3 are both used as the same-named terminals of a pair of reversely coupled inductors, and the other end of inductor L1 and the other end of inductor L3 are both used as the different-named terminals of a pair of reversely coupled inductors; Inductor L2 and inductor L4 form another pair of reversely coupled inductors, and one end of inductor L2 and one end of inductor L4 are both used as the same-named terminals of another pair of reversely coupled inductors, and the other end of inductor L2 and the other end of inductor L4 are both used as the different-named terminals of another pair of reversely coupled inductors. In this preferred embodiment, the reverse coupling method can reduce the equivalent inductance, make the dynamic response of the system faster, and the dynamic performance better.

[0073] See Figure 7 , Further, the present invention also uses a soft-switching branch to reduce the turn-on and turn-off losses of the switching device, increase the life of the switching device, and improve the efficiency of the wireless charging device. Specifically: The magnetic-coupled wireless charging device based on double buck without dead zone further includes a soft-switching branch;

[0074] The soft-switching branch includes IGBT tube S 11 、IGBT tube S 21 、inductor L' r1 、inductor L' r2 、inductor L r1 、inductor L r2 、capacitor C r1 、capacitor C r2 、diode D r1 、diode D r2 、diode D s1 and diode D s2 ;

[0075] The collector of IGBT tube S 21 is connected to the anode of diode D3, the emitter of IGBT tube S 21 is connected to one end of inductor L r2 ; one end of inductor L r2 is simultaneously connected to one end of inductor L' r2 and one end of capacitor C r2 ; the other end of inductor L' r2 is connected to the anode of diode D r2 ; the cathode of diode D r2 is connected to the other end of capacitor C r2 and the anode of diode D s2 simultaneously; the anode of diode Ds2 The cathode of

[0076] IGBT transistor S 21 is connected to the anode of diode D3. The emitter of IGBT transistor S 21 is connected to one end of inductor L r2 . One end of inductor L r2 is connected to one end of inductor L' r2 and one end of capacitor C r2 simultaneously. The other end of inductor L' r2 is connected to the anode of diode D r2 . The cathode of diode D r2 is connected to the other end of capacitor C r2 and the anode of diode D s2 simultaneously. The cathode of diode D s2 is connected to the cathode of diode D2;

[0077] IGBT transistor S 11 is connected to the anode of diode D4. The emitter of IGBT transistor S 11 is connected to one end of inductor L r1 . One end of inductor L r1 is connected to the other end of inductor L' r1 and one end of capacitor C r1 simultaneously. The other end of inductor L' r1 is connected to the anode of diode D r1 . The cathode of diode D r1 is connected to the other end of capacitor C r1 and the anode of diode D s1 simultaneously. The cathode of diode D s1 is connected to the cathode of diode D1.

[0078] In this preferred embodiment, the auxiliary soft-switching branch connected in parallel on the bridge arm provides a free path for the bridge arm and can simultaneously achieve zero-voltage switching (ZVS) of the switching device, that is, the voltage across the switching device can drop to 0 when the switching device is turned on or off. Therefore, the turn-on and turn-off losses of the switching device are reduced, and the service life of the switching element is increased.

[0079] Principle analysis:

[0080] In the inverter link of traditional inductive wireless charging devices, a bridge inverter circuit with two power tubes connected in series on the same bridge arm is generally adopted. When the switching tubes on the same bridge arm are simultaneously in the on state, this structure will cause a short circuit of the power supply, reducing the system reliability. To prevent the problem of bridge arm shoot-through in the traditional bridge inverter structure, dead time is usually added during the working cycle to facilitate the switching of the power tube states. In several solutions of the present invention, a double buck structure with a power tube and a diode connected in reverse parallel in series on the same bridge arm is adopted, thus avoiding the problem of mis-conduction of the same bridge arm and eliminating the need to add dead time, greatly improving the reliability of power transmission. The primary side circuit of the magnetic coupling wireless charging device based on double buck without dead time of the present invention is as Figure 8 shown.

[0081] Since the double buck full-bridge inverter circuit without dead time is composed of two symmetrical half-bridge circuits, the current in the inductor with filtering effect always flows unidirectionally. In the ideal case, the inductances of L1 and L3 are equal, and the inductances of L2 and L4 are equal. The current directions of the inductor currents i Lf1 and i Lf3 are as Figure 8 shown. When the inductor currents i Lf1 and i Lf3 are in the discontinuous conduction mode, the inductor currents of L1 and L3 are 0 at this time. Therefore, a non-linear voltage error related to the inductor current is introduced at the nodes of the corresponding power switching tubes S1 and S3, and the output current will be distorted. Taking the inductor L1 as an example, the influence of the continuous and discontinuous inductor current of the primary inductor L1 on the voltage across the switching device S1 is given as Figure 9 shown.

[0082] As can be seen from Figure 9 , the discontinuous inductor current of L1 causes non-linear noise to be introduced into the voltage across the power switching tube S1 in the loop, resulting in distortion of the output voltage. To ensure the quality of the output electrical energy, the inductor current of L1 should be in the continuous conduction mode. To ensure continuous inductor current, a bias current flowing from L1 to L3 needs to be added. At this time, the current relationship in the circuit is as follows:

[0083] i sum1 =i Lf1 +i Lf3 ;

[0084]

[0085] i sum1 is the sum of the current i Lf1 flowing through the inductor L1 and the current i Lf3 flowing through the inductor L3. i bias1The bias current added to inductors L1 and L3 to prevent discontinuous operation. To ensure that the circuit operates in a continuous state, it is necessary to ensure that the average inductor current is greater than the ripple of the corresponding inductor current, i.e., 〈i Lf1 〉>△i Lf1 ,〈i Lf3 〉>△i Lf3 ,where 〈i Lf1 > and <i Lf3 > respectively represent the average currents of inductors L1 and L3 within the switching period of the power switch, and △i Lf1 and △i Lf3 are the current ripples of inductors L1 and L3 respectively. Therefore, it can be set that:

[0086]

[0087] <i bias1 > represents the average value of i bias1 within the switching period of the power switch, <i sum1 > represents the average value of i sum1 within the switching period of the power switch, and i th1 is the first offset current, which is the offset current applied to prevent the discontinuous operation of the currents of L1 and L3. When the above conditions are met, the continuity of the inductor current can be ensured, and the distortion of the output current caused by the discontinuous inductor current can be avoided.

[0088] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not depart from the spirit and scope of the present invention as defined by the appended claims. It should be understood that different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A magnetic coupling wireless charging device based on double buck with dead zone free, characterized in that, It includes a double buck dead-time-free full-bridge inverter circuit, a filter circuit, a coupling coil M, an H-bridge rectifier circuit, and an LC circuit; The double buck dead-time free full-bridge inverter circuit is composed of two half-bridge inverter circuits connected in parallel, and is used to convert the input DC power supply U i into alternating current. After the alternating current is filtered by a filter circuit, it is coupled to an H-bridge rectifier circuit through a coupling coil M. After the H-bridge rectifier circuit rectifies the received filtered alternating current, the output direct current is filtered by an LC circuit and then supplies power to the load; The double buck dead-time-free full-bridge inverter circuit includes power switch tubes S1 to S4, and diodes D1 to D4; among them, power switch tube S1, power switch tube S3, diode D1, and diode D3 form the first half-bridge inverter circuit, and power switch tube S2, power switch tube S4, diode D2, and diode D4 form the second half-bridge inverter circuit; The drain of the power switch tube S1, the drain of the power switch tube S2, the cathode of the diode D3, and the cathode of the diode D4 are simultaneously connected to the positive pole of the DC power supply U i ; After the source electrode of power switch tube S1 is connected to the cathode of diode D1, it serves as an AC output terminal of the first half-bridge inverter circuit and is connected to the filter circuit; After the anode of diode D3 is connected to the drain of power switch tube S3, it serves as the other AC output terminal of the first half-bridge inverter circuit and is connected to the filter circuit; The anode of diode D1, the source of power switch S3, the anode of diode D2, and the source of power switch S4 are simultaneously connected to the negative pole of DC power supply U i After the source of power switch S2 and the cathode of diode D2 are simultaneously connected, they are used as an AC output terminal of the second half-bridge inverter circuit and connected to the filter circuit; After the anode of diode D4 is connected to the drain of power switch tube S4, it serves as the other AC output terminal of the second half-bridge inverter circuit and is connected to the filter circuit.

2. The magnetic coupling wireless charging device based on double buck without dead zone according to claim 1, wherein The filter circuit includes inductors L1 to L4 and capacitor C1; One end of inductor L1 is connected to the source electrode of power switch tube S1, one end of inductor L3 is connected to the anode of diode D3, and the other end of inductor L1 is simultaneously connected to the other end of inductor L3, one end of capacitor C1, and the same-name end of the primary winding of coupling coil M; One end of inductor L2 is connected to the source electrode of power switch tube S2, one end of inductor L4 is connected to the anode of diode D4, and the other end of inductor L2 is simultaneously connected to the other end of inductor L4, the other end of capacitor C1, and the different-name end of the primary winding of coupling coil M; The same-name end and different-name end of the secondary winding of coupling coil M are respectively connected to the two AC input terminals of the H-bridge rectifier circuit simultaneously.

3. The magnetic coupling wireless charging device based on double buck without dead zone according to claim 1, wherein The H-bridge rectifier circuit includes diodes D5, D6, D7, and D8; After the anode of diode D5 and the cathode of diode D6 are connected, it serves as the first AC input terminal of the H-bridge rectifier circuit; After the anode of diode D7 and the cathode of diode D8 are connected, it serves as the second AC input terminal of the H-bridge rectifier circuit; After the cathode of diode D5 and the cathode of diode D7 are connected, it serves as the positive output terminal of the H-bridge rectifier circuit; After the cathode of diode D6 and the cathode of diode D8 are connected, it serves as the negative output terminal of the H-bridge rectifier circuit.

4. The magnetic coupling wireless charging device based on double buck with dead zone free according to claim 1, characterized in that, The LC circuit includes inductor L5 and capacitor C2; The positive output terminal of the H-bridge rectifier circuit is connected to one end of inductor L5, and the other end of inductor L5 is connected to one end of capacitor C2 and then serves as the positive output terminal of the charging device and is connected to one end of the load; The negative output terminal of the H-bridge rectifier circuit is connected to the other end of capacitor C2 and then serves as the negative output terminal of the charging device and is connected to the other end of the load.

5. The magnetic coupling wireless charging device based on double buck and dead zone free according to claim 2, characterized in that, Inductors L1 and L3 form a pair of forward-coupled inductors, and one end of inductor L1 and one end of inductor L3 both serve as the same-name ends of a pair of forward-coupled inductors, and the other end of inductor L1 and the other end of inductor L3 both serve as the different-name ends of a pair of forward-coupled inductors; Inductor L2 and inductor L4 form another pair of forward-coupled inductors, and one end of inductor L2 and one end of inductor L4 are both used as the same-named ends of the other pair of forward-coupled inductors, and the other end of inductor L2 and the other end of inductor L4 are both used as the different-named ends of the other pair of forward-coupled inductors.

6. The magnetic coupling wireless charging device based on double buck with dead-time free according to claim 2, characterized in that, Inductor L1 and inductor L3 form a pair of backward-coupled inductors, and the other end of inductor L1 and one end of inductor L3 are both used as the same-named ends of the pair of backward-coupled inductors, and one end of inductor L1 and the other end of inductor L3 are both used as the different-named ends of the pair of backward-coupled inductors; Inductor L2 and inductor L4 form another pair of backward-coupled inductors, and the other end of inductor L2 and one end of inductor L4 are both used as the same-named ends of the other pair of backward-coupled inductors, and one end of inductor L2 and the other end of inductor L4 are both used as the different-named ends of the other pair of backward-coupled inductors.

7. The magnetic coupling wireless charging device based on double buck and dead zone free according to claim 1, characterized in that It further includes a soft-switching branch; The soft-switching branch includes IGBT transistor S 11 and IGBT transistor S 21 , inductor L' r1 , inductor L' r2 , inductor L r1 , inductor L r2 , capacitor C r1 , capacitor C r2 , diode D r1 , diode D r2 , diode D s1 and diode D s2 ; IGBT transistor S 21 The collector of the IGBT transistor S 21 is connected to the anode of the diode D3, and the emitter of the IGBT transistor S r2 is connected to one end of the inductor L r2 The other end of the inductor L r2 is connected to one end of the inductor L' and one end of the capacitor C r2 simultaneously. The other end of the inductor L' r2 is connected to the anode of the diode D r2 The anode of the diode D r2 is connected to the cathode of the capacitor C r2 and the anode of the diode D s2 simultaneously. The cathode of the diode D s2 is connected to the cathode of the diode D2; IGBT transistor S 21 The collector of the IGBT transistor S is connected to the anode of the diode D3. The emitter of the IGBT transistor S 21 is connected to one end of the inductor L r2 . The other end of the inductor L r2 is connected to one end of the inductor L' r2 and one end of the capacitor C r2 simultaneously. The other end of the inductor L' r2 is connected to the anode of the diode D r2 . The cathode of the diode D r2 is connected to the other end of the capacitor C r2 and the anode of the diode D s2 simultaneously. The cathode of the diode D s2 is connected to the cathode of the diode D2; IGBT transistor S 11 The collector of the IGBT transistor S is connected to the anode of the diode D4. The IGBT transistor S 11 The emitter of the IGBT transistor S is connected to one end of the inductor L r1 One end of the inductor L r1 The other end of the inductor L is connected to one end of the inductor L' r1 One end of the inductor L' and one end of the capacitor C r1 One end of the capacitor C are connected simultaneously. The other end of the inductor L' r1 The other end of the inductor L' is connected to the anode of the diode D r1 The anode of the diode D r1 The cathode of the diode D is connected to the other end of the capacitor C r1 The other end of the capacitor C and the anode of the diode D s1 The anode of the diode D are connected simultaneously. The cathode of the diode D s1 The cathode of the diode D is connected to the cathode of the diode D1.

8. The magnetic coupling wireless charging device based on double buck and dead zone free according to claim 1, wherein Power switching transistors S1 to S4 are all N-type MOSFET transistors.

9. The magnetic coupling wireless charging device based on double buck and dead zone free according to claim 1, characterized in that wherein, i sum1 = i Lf1 + i Lf3 , i sum2 = i Lf2 + i Lf4 , The said i sum1 is the sum of the current i flowing through inductor L1 Lf1 and the current i flowing through inductor L3 Lf3 ; i bias1 is the bias current applied to inductors L1 and L3, i sum2 is the current i flowing through inductor L2 Lf2 and the current i flowing through inductor L4 Lf4 ; i bias2 is the bias current applied to inductors L2 and L4, i th1 is the first offset current, i th2 is the second offset current.

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