An inductively coupled electrical energy transmission device

Abstract

The present invention relates to power electronic conversion technology, and provides an inductively coupled electrical energy transmission device, a bus capacitor, an anti-backflow diode, a primary capacitor, a converter, a primary inductor, and a secondary load. In this embodiment, by configuring a converter with a variable switching structure, the proposed electromagnetic induction energy transfer device can decouple the frequency tracking process and the energy injection process, achieving a topological structure in which the system operating frequency adapts to resonance and the power is regulated with variable periods, solving the contradictions between the time-varying system parameters and the resonance frequency constraints in the prior art, as well as the problems such as difficulties in frequency tracking and power control caused by the time-varying system parameters. The topological structure provided in this embodiment has the characteristics of simple and convenient switching control strategies, and the switches always operate under soft-switching conditions.

Description

Technical Field

[0001] The present invention relates to a power electronic conversion technology, and particularly to an inductively coupled electrical energy transmission device. Background Art

[0002] Inductively coupled electrical energy transmission is a non-contact way of transmitting electrical energy, which is widely used in fields such as power conversion, physical isolation, wireless power supply, and inductive heating. Inductively coupled electrical energy transmission adopts the inductive power transmission technology (IPT). Its basic principle is to drive the transmitting coil (primary inductor) with high-frequency electrical energy on the primary side (primary winding), and the high-frequency energy is transferred to the receiving coil (secondary inductor) on the secondary side (secondary winding) through electromagnetic magnetic flux linkage. The IPT system is a loosely coupled transformer system in principle. In a loosely coupled transformer, the inductively coupled energy between the primary and secondary is very weak, and the mutual inductance of the system is much smaller than the leakage inductance. The small mutual inductance leads to high reactive power and extremely low transmission efficiency. To solve the problems of bus bar circulation and low transmission efficiency caused by large reactive power, a resonance network is usually added to the primary circuit and the secondary circuit to compensate for the reactive power, so as to eliminate the circulation and improve the transmission efficiency to solve the problem of poor coupling ability. The added resonance network in the circuit causes strong adhesion and coupling between the converter and the resonance circuit. The strong coupling characteristic requires that the operating frequency and phase of the converter must be consistent with the resonance network, and the change of the system switching state can only be carried out at the zero crossing point of the primary current. Otherwise, the switching elements in the converter will lose the soft-switching operating conditions, which greatly increases the difficulty of the switching control strategy.

[0003] The actual application scenario of the IPT system is relatively complex and is a variable parameter system, such as load change, coil asymmetry, air gap change, etc. The parameter change will cause the resonance network frequency to drift, resulting in detuning between the converter and the resonance network, which greatly affects the actual application of the IPT system. Therefore, many scholars and engineers are looking for better control devices and methods for the IPT system. Summary of the Invention

[0004] An embodiment of the present invention provides an inductively coupled electrical energy transmission device and its control method to solve the problem of system detuning and reduce the control difficulty.

[0005] The present invention provides an inductively coupled electrical energy transmission device, including:

[0006] Bus capacitor; anti-reverse diode; primary capacitor; converter; primary inductor; secondary load;

[0007] Wherein, both ends of the bus capacitor are respectively connected to the external power supply UDC+ port and UDC− port;

[0008] The converter includes port A1, port A2, port B1, port B2, port B3, and port B4;

[0009] The positive terminal of the anti - reverse - flow diode is connected to the external power supply UDC + port, and the negative terminal is connected to the converter A1 port. The external power supply UDC - port is connected to the converter A2 port;

[0010] One end of the primary capacitor is connected to the converter B1 port and the other end is connected to the B3 port. One end of the primary inductor is connected to the converter B2 port and the other end is connected to the B4 port;

[0011] There is an electromagnetic induction magnetic flux between the primary inductor and the secondary load. Through this electromagnetic induction magnetic flux, the energy in the primary inductor is transferred to the secondary load;

[0012] If the converter is in the first working state, the converter A1 port is connected to the B2 port, and the A2 port is connected to the B4 port; the external power supply UDC injects current into the converter A1 port through the anti - reverse - flow diode. The current injected into the A1 port flows out through the B2 port and is injected into the primary inductor;

[0013] If the converter is in the second working state, the converter B1 port is connected to the B2 port, and the B3 port is connected to the B4 port. The external power supply UDC stops injecting current into the converter. The primary capacitor and the primary inductor are connected through the B1 port, B2 port, B3 port, and B4 port of the converter to form a resonant tank and generate resonance;

[0014] If the converter is in the third working state, the converter A1 port, A2 port, B1 port, B2 port, B3 port, and B4 port are separated and not connected; the external power supply UDC stops injecting current into the converter. The primary capacitor and the primary inductor are isolated from each other and the resonance stops. In specific working scenarios, the third working state can be cancelled;

[0015] During the first working state and the second working state, the primary inductor transfers energy to the secondary load through the electromagnetic induction magnetic flux.

[0016] The converter includes a first power switch, a second power switch, a third power switch, a first diode, a second diode, and a third diode.

[0017] The secondary load includes a secondary inductor and / or a secondary capacitor connected in parallel or in series with the secondary inductor. There is an electromagnetic induction magnetic flux between the secondary inductor and the primary inductor, and through this electromagnetic induction magnetic flux, the energy in the primary inductor is transferred to the secondary load; the secondary load includes the metal to be heated.

[0018] The primary inductor and the secondary inductor are provided with magnetic cores.

[0019] The first diode is the body diode of the first power switch, the second diode is the body diode of the second power switch, and the third diode is the body diode of the third power switch.

[0020] When the converter is in the first working state and the third working state, the primary capacitor voltage is clamped at the bus capacitor voltage.

[0021] The control strategy for the working state of the converter is as follows:

[0022] When the first power switch, the second power switch, and the third power switch are all turned off, the converter is in the third working state; when the first power switch and the second power switch are turned on and the third power switch is turned off, the converter is in the first working state; when the first power switch is turned off, the second power switch is turned on, the third power switch is turned on, or the second power switch and the third power switch are both turned on, the converter is in the second working state.

[0023] The control sequence of the working states of the converter is: the first working state, the second working state, the third working state, the first working state, and it cycles in this pattern; in specific cases, the control sequence of the working states of the converter is: the first working state, the second working state, the first working state, and it cycles in this pattern.

[0024] The second working state of the converter includes a first transition state, a resonance state, and a second transition state; when the second power switch is turned on and the third diode is turned on, the converter is in the first transition state; when the third power switch is turned on and the second diode is turned on, the converter is in the second transition state; when the second power switch and the third power switch are turned on and the second diode and the third diode conduct alternately, the converter is in the resonance state.

[0025] In the electromagnetic induction energy transfer device according to the embodiments of the present invention, by configuring a converter with a variable switching structure, the electromagnetic induction energy transfer device proposed by the present invention can decouple the frequency tracking process and the energy injection process, achieving a topological structure in which the operating frequency of the system is adaptively resonant and the power is regulated with a variable period, solving the contradiction between the time-varying system parameters and the resonant frequency constraint in the prior art, as well as the problems of difficult frequency tracking and power control caused by the time-varying system parameters. In addition, the topological structure provided by the embodiments of the present invention has the characteristics of simple and convenient switching control strategy, and the switches always operate under soft-switching conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the application of an inductive coupling electrical energy transmission device according to the present invention.

[0027] Figure 2 It is a schematic diagram of the application topology of the converter of an inductive coupling electrical energy transmission device according to the present invention in the first working state.

[0028] Figure 3 It is a schematic diagram of the application topology of the converter of an inductive coupling electrical energy transmission device according to the present invention in the second working state.

[0029] Figure 4 It is a schematic diagram of the topology of the first embodiment of the converter of an inductive coupling electrical energy transmission device according to the present invention.

[0030] Figure 5 It is a schematic diagram of the topology of the first embodiment of the secondary load of an inductive coupling electrical energy transmission device according to the present invention.

[0031] Figure 6 It is a schematic diagram of the topology of the second embodiment of the secondary load of an inductive coupling electrical energy transmission device according to the present invention.

[0032] Figure 7 It is a schematic diagram of the timing waveform of the first embodiment of the converter of an inductive coupling electrical energy transmission device according to the present invention.

[0033] Figure 8 It is a schematic diagram of the first working state of the first embodiment of the converter of an inductive coupling electrical energy transmission device according to the present invention.

[0034] Figure 9 It is a schematic diagram of the first transition state of the second working state of the first embodiment of the converter of an inductive coupling electrical energy transmission device according to the present invention.

[0035] Figure 10 It is a schematic diagram of the resonant state of the second working state of the first embodiment of the converter of an inductive coupling electrical energy transmission device according to the present invention.

[0036] Figure 11Schematic diagram of the second transition state of the second working state of the converter of an inductive coupling electric energy transmission device according to the present invention. Detailed implementation manners

[0037] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0038] It should be noted that when a component is referred to as being "fixed to" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component at the same time.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0040] To at least partially solve the problems existing in the prior art, for example, how to solve the problems such as difficult frequency tracking of the converter of a radio energy transmission device and / or difficult control of the state change of the converter switching components. An inductive coupling electric energy transmission device and its control method are proposed to solve the system detuning problem and reduce the control difficulty. An inductive coupling electric energy transmission device is provided in an embodiment of the present invention, wherein the inductive coupling electric energy transmission device includes:

[0041] Bus capacitor; anti-reverse diode; primary capacitor; converter; primary inductor; secondary load;

[0042] Wherein, both ends of the bus capacitor are respectively connected to the external power supply UDC+ port and the UDC- port.

[0043] The converter includes ports A1, A2, B1, B2, B3, and B4.

[0044] The positive end of the anti-reverse diode is connected to the external power supply UDC+ port, the negative end is connected to the converter A1 port, and the external power supply UDC- port is connected to the converter A2 port.

[0045] One end of the primary capacitor is connected to port B1 of the converter, and the other end is connected to port B3; one end of the primary inductor is connected to port B2 of the converter, and the other end is connected to port B4.

[0046] There is an electromagnetic induction magnetic flux between the primary inductor and the secondary load. Through this electromagnetic induction magnetic flux, the energy in the primary inductor is transferred to the secondary load.

[0047] If the converter is in the first working state, port A1 of the converter is connected to port B2, and port A2 is connected to port B4; the external power supply UDC injects current into port A1 of the converter through the anti - reflux diode, and the current injected into port A1 flows out through port B2 and is injected into the primary inductor.

[0048] If the converter is in the second working state, port B1 of the converter is connected to port B2, and port B3 is connected to port B4. The external power supply UDC stops injecting current into the converter. The primary capacitor and the primary inductor are connected through ports B1, B2, B3, and B4 of the converter to form a resonant tank and generate resonance.

[0049] If the converter is in the third working state, ports A1, A2, B1, B2, B3, and B4 of the converter are separated and not connected; the external power supply UDC stops injecting current into the converter. The primary capacitor and the primary inductor are isolated from each other and the resonance stops. In specific working scenarios, the third working state can be cancelled.

[0050] During the first and second working states, the primary inductor transfers energy to the secondary load through the electromagnetic induction magnetic flux.

[0051] The converter includes a first power switch, a second power switch, a third power switch, a first diode, a second diode, and a third diode.

[0052] The secondary load includes a secondary inductor and / or a secondary capacitor connected in parallel or in series with the secondary inductor. There is an electromagnetic induction magnetic flux between the secondary inductor and the primary inductor. Through this electromagnetic induction magnetic flux, the energy in the primary inductor is transferred to the secondary load.

[0053] The primary inductor and the secondary inductor are provided with magnetic cores.

[0054] The first diode is the body diode of the first power switch, the second diode is the body diode of the second power switch, and the third diode is the body diode of the third power switch.

[0055] When the converter is in the first working state and the third working state, the primary capacitor voltage is clamped at the bus capacitor voltage.

[0056] The control strategy for the working state of the converter is as follows:

[0057] When the first power switch, the second power switch, and the third power switch are all turned off, the converter is in the third working state; when the first power switch and the second power switch are turned on and the third power switch is turned off, the converter is in the first working state; when the first power switch is turned off, the second power switch is turned on, the third power switch is turned on, or both the second power switch and the third power switch are turned on, the converter is in the second working state.

[0058] The control sequence of the converter's working states is: the first working state → the second working state → the third working state → the first working state,... and so on, repeating in this pattern; in specific cases, the converter's working sequence is: the first working state → the second working state → the first working state,... and so on, repeating in this pattern.

[0059] The second working state of the converter includes a first transition state, a resonance state, and a second transition state; when the second power switch is turned on and the third diode is turned on, the converter is in the first transition state; when the third power switch is turned on and the second diode is turned on, the converter is in the second transition state; when the second power switch and the third power switch are turned on, and the second diode and the third diode conduct alternately, the converter is in the resonance state.

[0060] Figure 1 This is an application schematic diagram of an inductive coupled electric energy transmission device of the present invention, used to illustrate a transmission device that converts direct current into high-frequency alternating current and provides energy to the secondary through electromagnetic coupling. The inductive coupled electric energy transmission device includes a bus capacitor 1, an anti-backflow diode 2, a primary capacitor 3 (Cp), a converter 4, a primary inductor 5 (Lp), and a secondary load 6.

[0061] The converter 4 includes ports A1, A2, B1, B2, B3, and B4.

[0062] Both ends of the bus capacitor 1 are respectively connected to the external power supply UDC+ port and the UDC− port; the positive end of the anti-backflow diode 2 is connected to the external power supply UDC+ port, and the negative end is connected to port A1 of the converter 4; the external power supply UDC− port is connected to port A2 of the converter 4.

[0063] One end of the primary capacitor 3 is connected to the B1 port of the converter 4, and the other end is connected to the B3 port; one end of the primary inductor 5 is connected to the B2 port of the converter 4, and the other end is connected to the B4 port of the converter 4.

[0064] There is an electromagnetic induction magnetic flux between the primary inductor 5 and the secondary load 6. Through the electromagnetic induction magnetic flux, the energy in the primary inductor 5 is transferred to the secondary.

[0065] Figure 2 This is a schematic diagram of the application topology of the converter 4 of an inductive coupled electric energy transmission device of the present invention in the first working state. Refer to Figure 2 , in the first working state, the A1 port of the converter 4 is connected to the B2 port, and the A2 port is connected to the B4 port. The external power supply UDC injects the current ib into the A1 port of the converter 4 through the anti-backflow diode 2. The current ib injected into the A1 port flows out of the B2 port to form the current ip and injects into the primary inductor 5 (Lp);

[0066] Figure 3 This is a schematic diagram of the application topology of the converter 4 of an inductive coupled electric energy transmission device of the present invention in the second working state. Refer to Figure 3 , in the second working state, the B1 port of the converter 4 is connected to the B2 port, and the B3 port is connected to the B4 port. The primary capacitor 3 and the primary inductor 5 form a resonant tank, and the system starts to resonate and forms a resonant current ic = ip.

[0067] Figure 4 This is a schematic diagram of the topology of the first embodiment of the converter 4 of an inductive coupled electric energy transmission device of the present invention. Refer to Figure 4 , the converter 4 includes a first power switch 41, a second power switch 42, a third power switch 43, a first diode 44, a second diode 45, and a third diode 46. The first diode 44 is the body diode of the first power switch 41, the second diode 45 is the body diode of the second power switch 42, and the third diode 46 is the body diode of the third power switch 43.

[0068] Continue to refer to Figure 4 , the drain of the first power switch 41 is connected to the A1 port of the converter 4, the source is connected to the B1 port, the drain of the second power switch 42 is connected to the B1 port of the converter 4, the source is connected to the B2 port, the drain of the third power switch 43 is connected to the B3 port of the converter 4, the source is connected to the B4 port, and the A2 port of the converter 4 is connected to the B4 port.

[0069] Figure 5This is a schematic topological diagram of the first embodiment of the secondary load 6 of an inductive coupling electric energy transmission device according to the present invention. Refer to Figure 5 , the secondary load 6 includes a secondary inductor 61, a compensation capacitor 62, and a load 63. The compensation capacitor 62 can be connected to the secondary inductor 61 in series or parallel to form a secondary compensation loop. The output of the secondary compensation loop drives the load 63 to provide energy for it. In some cases, the compensation capacitor 62 can be omitted, and the secondary inductor is directly connected to the load 63 to provide energy for it.

[0070] Figure 6 This is a schematic topological diagram of the second embodiment of the secondary load 6 of an inductive coupling electric energy transmission device according to the present invention. As Figure 6 shown, the secondary load 6 includes a metal part 64. When an alternating current flows through the primary inductor 5, an alternating magnetic field is generated. The alternating magnetic field transfers energy to the secondary load 6 through the electromagnetic coupling magnetic flux, and eddy currents are induced in the metal part 64. The induced eddy currents heat the metal part 64.

[0071] Figure 7 This is a schematic diagram of the timing waveform of the first embodiment of the converter of an inductive coupling electric energy transmission device according to the present invention. This waveform diagram is used to illustrate the relationship between the working timing of the first power switch 41, the second power switch 42, and the third power switch 43 in the converter 4 and the working state of the system. Among them, S1, S2, and S3 respectively indicate the on-off states of the first power switch 41, the second power switch 42, and the third power switch 43. They are on in the high level and off in the low level.

[0072] Refer to Figure 7 :

[0073] In the interval [t1, t2], S1 and S2 are at high level, and S3 is at low level. At this time, the converter 4 is in the first working state, and the primary capacitor voltage 3Uc is clamped at UDC. In this state, the current ib flowing through the anti-backflow diode 2 and flowing into the A1 port rises linearly, and the current ip flowing into the primary inductor 5 also rises linearly, and ib = ip. At this time, there is no current in the primary capacitor 3, ic = 0.

[0074] In the interval [t2, t5], S1 is at low level, and at least one of S2 and S3 is at high level. At this time, the converter 4 is in the second working state. At this time, the system starts to resonate, and uc, ip, and ic start to change sinusoidally, and ib = 0.

[0075] In the interval [t5, t6], S1, S2, and S3 are all at low level. At this time, the converter 4 is in the third working state. At this time, uc is clamped at UDC, and ib, ip, and ic are all 0.

[0076] The interval [t6, t10] is a new working cycle, and the system repeats these cycles cyclically to chop the DC power supply UDC into high-frequency alternating current.

[0077] Further refer to Figure 7 :

[0078] At time t2, S1 is turned off, and at this time, the converter 4 switches from the first working state to the second working state. However, S3 is delayed by a time and does not start conducting until t3. Note that t3 is selected after t2 and before the first zero-crossing point of ip. Such a selection creates a soft-switching condition for S3, and the interval [t2, t3] is defined as the first transition state of the second working state.

[0079] After S2 is turned off at time t4, after a delay of the same time, S3 is turned off until time t5, and the converter 4 is switched from the second working state to the third working state. Such a selection also creates a soft-switching condition for S3, and the interval [t4, t5] is defined as the second transition state of the second working state.

[0080] Figure 8 This is a schematic diagram of the first working state of the converter of the first embodiment of the inductive coupled electric energy transmission device of the present invention. Combining Figure 7 、 Figure 8 , in the interval [t1, t2], the first power switch 41 and the second power switch 42 in the converter 4 are turned on, the A1 port is connected to the B2 port, and at the same time, the A2 port is connected to the B4 port. The power supply UDC is applied to the primary inductor 5 via the anti-backflow diode 2 to form a linearly rising current ip.

[0081] Figure 9 This is a schematic diagram of the first transition state of the second working state of the converter of the first embodiment of the inductive coupled electric energy transmission device of the present invention. Combining Figure 7 、 Figure 9, in the interval [t2, t3], the first power switch 41 in the converter 4 is turned off and the second power switch 42 is turned on. Note that the third power switch 43 has not been turned on yet. Since the first power switch 41 is turned off, the power supply UDC stops injecting current into the primary inductor 5. However, because the current ip in the primary inductor 5 cannot change abruptly, the third diode 46 is turned on to provide a path for ip. At the same time, since the first power switch 41 is turned off, the connection between port A2 and port B4 is meaningless. At this time, port B1 is connected to port B2, and port B3 is connected to port B4. The primary capacitor 3 and the primary inductor 4 form a resonant tank. The primary inductor current ip continues to be maintained but starts to change sinusoidally. At the same time, the primary capacitor current ic starts to appear, and ic = ip. Since the third diode 46 is turned on, it provides a zero-voltage turn-on soft-switching condition for the third power switch 43, forming the first transition state of the second operating state.

[0082] Figure 10 This is a schematic diagram of the resonant state of the second operating state of the converter of the first embodiment of an inductive coupled electric energy transmission device according to the present invention. Since the third power switch 43 is not turned on in the first transition state of the second operating state, the resonant tank formed by the primary capacitor 3 and the primary inductor 5 is not complete and can only conduct current unidirectionally. It is necessary to turn on the third power switch 43 in the first transition state. Combining Figure 7 , Figure 10 , at time t3, the third power switch 43 is turned on with zero voltage. Therefore, in the interval [t2, t3], the second power switch 42 and the third power switch 43 are turned on, and the second diode 45 and the third diode 46 are alternately turned on. The resonant tank formed by the primary capacitor 3 and the primary inductor 5 can conduct current bidirectionally, and the system enters the resonant state of the second operating state. uc, ib, ip, and ic all change sinusoidally.

[0083] Figure 11 This is a schematic diagram of the second transition state of the second operating state of the converter of the first embodiment of an inductive coupled electric energy transmission device according to the present invention. Combining Figure 7 , Figure 11 , in the interval [t4, t5], the second diode 45 is in the on state. Therefore, the second power switch 42 is turned off with zero voltage in the interval [t4, t5]. Since the second power switch 42 is turned off after t4, the resonant tank formed by the primary capacitor 3 and the primary inductor 5 returns to the unidirectional conduction state, preparing for the system to exit the second operating state. Therefore, [t4, t5] is called the second transition state of the second operating state. In the second transition state of the second operating state, uc, ib, ip, and ic all change sinusoidally. When reaching time t5, ip decreases to 0. Therefore, the third power switch 43 can be turned off under the zero-current soft-switching condition, and the system exits the second operating state and enters the third state.

[0084] Further reference is made to Figure 7 and Figure 8 , it can be seen that by changing the duration of the first operating state of the converter 4, the magnitude of the current ip injected into the primary inductor within the time period [t1, t2] can be changed, thereby changing the magnetic field energy and achieving the purpose of controlling the system power.

[0085] Further reference is made to Figure 7 and Figure 9 Figure 10 Figure 11 , it can be seen that within the time period [t2, t5], the duration of the second operating state of the converter 4 is completely determined by the parameters of the resonant tank formed by the primary capacitor 3 and the primary inductor 4, that is, the system can adapt to changes in system parameters and achieve the purpose of automatically tracking the operating frequency of the system.

[0086] It can be understood that in Figure 2 , Figure 3 , Figure 8 , Figure 11 , the components and circuits through which current flows are represented by thick solid lines, and the components and circuits through which no current flows are represented by thin solid lines.

[0087] The electromagnetic induction energy transfer device in the embodiment of the present invention can decouple the frequency tracking process and the energy injection process by configuring a converter with a variable switch structure, achieving a topological structure in which the operating frequency of the system is adaptively resonant and the power is regulated with a variable period, and solving the contradictions between the time-varying system parameters and the resonant frequency constraint in the prior art, as well as the difficulties in frequency tracking and power control caused by the time-varying system parameters. In addition, the topological structure provided by the embodiment of the present invention has the characteristics of simple and convenient switch control strategy, and the switch always operates under soft-switching conditions.

[0088] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An inductive coupling electrical energy transmission device, characterized in that Comprising: Bus capacitor; Anti - reflux diode; primary capacitor; Converter; Primary inductor; Secondary load; Wherein, both ends of the bus capacitor are respectively connected to the external power supply UDC + port and UDC - port; The converter includes ports A1, A2, B1, B2, B3, B4; The positive terminal of the anti - reflux diode is connected to the external power supply UDC + port, and the negative terminal is connected to the converter A1 port. The external power supply UDC - port is connected to the converter A2 port; One end of the primary capacitor is connected to the converter B1 port, and the other end is connected to the B3 port. One end of the primary inductor is connected to the converter B2 port, and the other end is connected to the B4 port; There is an electromagnetic induction magnetic flux between the primary inductor and the secondary load. Through the electromagnetic induction magnetic flux, the energy in the primary inductor is transferred to the secondary load; If the converter is in the first working state, the converter A1 port is connected to the B2 port, and the A2 port is connected to the B4 port. The external power supply UDC injects current into the converter A1 port through the anti - reflux diode. The current injected into the A1 port flows out through the B2 port and is injected into the primary inductor; If the converter is in the second working state, the converter B1 port is connected to the B2 port, and the B3 port is connected to the B4 port. The external power supply UDC stops injecting current into the converter. The primary capacitor and the primary inductor are connected through the B1 port, B2 port, B3 port, and B4 port of the converter to form a resonant tank and generate resonance; If the converter is in the third working state, the converter A1 port, A2 port, B1 port, B2 port, B3 port, and B4 port are separated and not connected. The external power supply UDC stops injecting current into the converter. The primary capacitor and the primary inductor are isolated from each other and stop resonating; During the first working state and the second working state, the primary inductor transfers energy to the secondary load through the electromagnetic induction magnetic flux.

2. The inductive coupling electric energy transmission device according to claim 1, characterized in that, The converter includes a first power switch, a second power switch, a third power switch, a first diode, a second diode, and a third diode.

3. An inductive coupling electric energy transmission device according to claim 1, characterized in that, The secondary load includes a secondary inductor and / or a secondary capacitor connected in parallel or in series with the secondary inductor. There is an electromagnetic induction magnetic flux between the secondary inductor and the primary inductor. Through the electromagnetic induction magnetic flux, the energy in the primary inductor is transferred to the secondary load.

4. The inductive coupling electric energy transmission device according to claim 3, characterized in that The secondary load includes the metal to be heated.

5. An inductive coupling electric energy transmission device according to claim 1 or 3, characterized in that The primary inductor and the secondary inductor are provided with magnetic cores.

6. An inductive coupling electric energy transmission device according to claim 2, wherein The first diode is the body diode of the first power switch, the second diode is the body diode of the second power switch, and the third diode is the body diode of the third power switch.

7. An inductive coupling electric energy transmission device according to claim 1, characterized in that When the converter is in the first working state and the third working state, the primary capacitor voltage is clamped at the bus capacitor voltage.

8. The inductive coupling electric energy transmission device according to claim 2, wherein The converter working state control strategy is: When the first power switch, the second power switch, and the third power switch are all turned off, the converter is in the third operating state; when the first power switch and the second power switch are turned on and the third power switch is turned off, the converter is in the first operating state; when the first power switch is turned off, the second power switch is turned on, the third power switch is turned on, or both the second power switch and the third power switch are turned on, the converter is in the second operating state.

9. An inductive coupling electric energy transmission device according to claim 8, characterized in that, By controlling the timing of the first power switch, the second power switch, and the third power switch, the operating sequence of the converter is controlled as follows: the first operating state, the second operating state, the third operating state, the first operating state, or the first operating state, the second operating state, the first operating state, and this pattern repeats cyclically.

10. The inductive coupling electric energy transmission device according to claim 2, characterized in that, The second operating state of the converter includes a first transition state, a resonant state, and a second transition state; when the second power switch is turned on and the third diode is turned on, the converter is in the first transition state; when the third power switch is turned on and the second diode is turned on, the converter is in the second transition state; when the second power switch and the third power switch are turned on and the second diode and the third diode conduct alternately, the converter is in the resonant state.

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