CN109274282B

CN109274282B - Split type parallel resonance inverter formed by double-T-shaped topological inversion bridge

Info

Publication number: CN109274282B
Application number: CN201811423805.1A
Authority: CN
Inventors: 胡聪权; 刘博�
Original assignee: Baoding Zshc Electrical Co ltd
Current assignee: Baoding Zshc Electrical Co ltd; Hu Congquan
Priority date: 2018-11-27
Filing date: 2018-11-27
Publication date: 2024-05-28
Anticipated expiration: 2038-11-27
Also published as: CN109274282A

Abstract

The invention discloses a split parallel resonant inverter formed by double-T topology inverter bridges, which comprises an inverter bridge, leakage reactance L3, an LC resonant circuit, a capacitor C12, a capacitor C22 and a soft connection structure, and solves the problem that the electric characteristics of the inverter are influenced by distributed inductance of a connector between the inverter bridge and the LC resonant circuit due to the fact that copper polar plates are required to be integrally and compactly assembled between the inverter bridge and the LC resonant circuit of the current parallel resonant inverter formed by the double-T topology inverter bridges, so that the split soft connection between the two parts of the double-T topology inverter bridge and the LC resonant circuit can be realized, and the LC resonant circuit can be led out for several meters on the premise that the electric characteristics of the inverter are not influenced by the distributed inductance of the connector between the inverter bridge and the LC resonant circuit, the overall efficiency is not reduced basically, and the current loss is not increased basically, so as to meet the use requirements of the inverter or an induction heating power supply formed by the inverter in different heating processes and heating occasions.

Description

Split type parallel resonance inverter formed by double-T-shaped topological inversion bridge

Technical Field

The invention relates to the technical field of power supplies, in particular to a split type parallel resonance inverter formed by double-T topology inverter bridges.

Background

The inverter is an important component of the power conversion device. The parallel resonant inverter formed by the double-T topology inverter bridge is widely applied to inverter power supply devices such as induction heating power supplies, resistance welding power supplies and the like because of the advantages of high efficiency, high output voltage, low withstand voltage requirement on switching elements, compact assembly structure, very low leakage inductance of a main loop distributed inductor and a capacitor bank, low high-frequency loss, low self induced heating value, capability of outputting very high resonant current and resonant volt-ampere capacity and the like.

The main circuit of the parallel resonant inverter formed by the double-T topology inverter bridge mainly comprises an inverter bridge and an LC parallel resonant circuit, and the distributed inductance formed by different connection modes between the inverter bridge and the LC parallel resonant circuit can have serious adverse effect on the electrical characteristics of the inverter. Therefore, the existing connection mode between the two devices must take an integrated and compact structural assembly mode, so as to avoid that the distributed inductance generated by the connection between the two devices affects the electrical characteristics of the inverter. The topology of the conventional parallel resonant inverter formed by the double-T topology inverter bridge is shown in fig. 1 and 2, and the integrated, compact assembly and structural form of the conventional parallel resonant inverter formed by the double-T topology inverter bridge is shown in fig. 3.

Because the parallel resonant inverter formed by the double-T topology inverter bridge is in a parallel resonant mode, the resonant current of the tank LC resonant circuit is multiplied by the Q value of the input direct current of the inverter or the output current of the inverter bridge (Q is the quality factor of the LC resonant circuit). Thus, for a power supply device of several hundred kilowatts, the current in the LC tank, i.e. the ac current through the inductor, may be as high as several tens of thousands of amperes, in an actual induction heating or resistance welding application, the inductance L7 in the LC tank is the welding electrode in an induction heating application or resistance welding application. Sometimes, in order to meet the field requirements of the actual application, it is necessary to draw the inductor or the welding electrode from the power supply device for a distance of several meters. However, since the current flowing through the inductor is large, in order to remotely separate the inductor or the welding electrode from the power supply device, that is, from the resonance capacitor C in the LC resonant tank, a thick water-cooled cable is necessary for connection, which causes problems such as increased cable inductance, large current loss, severely reduced overall efficiency, inconvenient connection and use, and the like, and cannot meet the requirements of production applications.

Disclosure of Invention

The invention aims to provide a split type parallel resonant inverter formed by double-T-shaped topological inverter bridges, which can realize split arrangement of the inverter bridges and the LC resonant circuits in the inverter on the premise that the distributed inductance of a connector between the inverter bridges and the LC resonant circuits does not have obvious adverse effect on the electrical characteristics of the inverter, and meets the use requirements of the inverter or an induction heating power supply formed by the inverter in different induction heating processes and different heating occasions.

In order to achieve the above object, the present invention provides the following solutions:

The split type parallel resonant inverter comprises an inverter bridge, an LC resonant circuit, a leakage reactance L3, a capacitor C12, a capacitor C22 and a soft connection structure; the flexible connection structure comprises twisted pair wires, twisted pair cables, coaxial cables and shielding cables;

the inverter bridge is of a double T-shaped topological structure which is vertically symmetrical; the inverter bridge consists of a first boost inductor L1, a positive module, a second boost inductor L2 and a negative module, wherein the output end of the positive module is the positive output end of the inverter bridge, and the output end of the negative module is the negative output end of the inverter bridge;

The LC resonant circuit is of a topological structure which is vertically symmetrical; the LC resonance loop is formed by connecting an inductance network with a capacitor group formed by connecting a third capacitor C3, a first capacitor C1, a second capacitor C2 and a fourth capacitor C4 in series, wherein the capacitance of the first capacitor C1 is equal to that of the second capacitor C2, and the capacitance of the third capacitor C3 is equal to that of the fourth capacitor C4;

The capacitance C12 is equal to the capacitance C22, and the capacitance C12 is smaller than the capacitance C1, and the capacitance C22 is smaller than the capacitance C2;

The capacitor C12 is connected between the positive electrode output end of the inverter bridge and the node O of the inverter bridge, and the capacitor C22 is connected between the node O of the inverter bridge and the negative electrode output end of the inverter bridge; the node O is a floating zero voltage reference point of the inverter bridge;

in actual use, the soft connection structure is used for connecting the positive electrode output end of the inverter bridge with the positive electrode input end of the LC resonance circuit and connecting the negative electrode output end of the inverter bridge with the negative electrode input end of the LC resonance circuit so as to realize an inversion function.

Optionally, the number of the positive modules and the number of the negative modules are determined according to the actual power output power requirement;

Each positive module consists of a first bridge arm A+ and a second bridge arm B+; the first bridge arm A+ is composed of a first switch S1; the second bridge arm B+ is composed of a second switch S2; each negative module consists of a first bridge arm A-and a second bridge arm B-; the first bridge arm A-is composed of a fourth switch S4; the second bridge arm B-is composed of a third switch S3;

The first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 are parallel groups of a plurality of switch units formed by power switch components;

One end of the first switch S1 is connected with one end of the second switch S2, and a common end of the first switch S1 and the second switch S2 is a direct current input positive end of the positive module; one end of the third switch S3 is connected with one end of the fourth switch S4, the common end of the third switch S3 and the fourth switch S4 is the negative direct current input end of the negative module, and the positive direct current input end of the positive module is also connected with the positive electrode of the direct current voltage through the first boost inductor L1; the direct current input negative end of the negative module is also connected with the negative electrode of the direct current voltage through the second boost inductor L2;

The other end of the second switch S2 is connected with the other end of the third switch S3, and the common end of the second switch S2 and the third switch S3 is a node O of the inverter bridge; the other end of the first switch S1 is the positive electrode output end of the inverter bridge; the other end of the fourth switch S4 is the negative electrode output end of the inverter bridge;

The first capacitor C1 and the second capacitor C2 of the LC resonant circuit are all capacitor groups formed by connecting a plurality of capacitors in parallel, and the third capacitor C3 and the fourth capacitor C4 are all capacitor groups formed by connecting a plurality of capacitors in parallel or are formed by connecting a plurality of groups of capacitors in parallel in series; the capacitor C12 and the capacitor C22 are both a capacitor parallel group formed by one or more capacitors;

The positive electrode input end of the inductance network is connected with one end of the third capacitor C3, the other end of the third capacitor C3 is connected with one end of the first capacitor C1, the other end of the first capacitor C1 is connected with one end of the second capacitor C2, the other end of the second capacitor C2 is connected with one end of the fourth capacitor C4, and the other end of the fourth capacitor C4 is connected with the negative electrode input end of the inductance network;

The connection point between the first capacitor C1 and the second capacitor C2 is a node D; the connection point of the first capacitor C1 and the third capacitor C3 is the positive input end of the LC resonance loop; the connection point of the second capacitor C2 and the fourth capacitor C4 is the negative input end of the LC resonant circuit.

Optionally, the ratio of the capacitances of the capacitor C12, the first capacitor C1, the capacitor C22, and the second capacitor C2 is C12: c1 =c22: c2 =1:5 to 1:10.

Optionally, one end of the leakage reactance L3 is connected with an anode input end of the LC resonant circuit, the other end of the leakage reactance L3 is connected with a cathode input end of the LC resonant circuit, and a middle tap of the leakage reactance L3 is connected with a node D of the LC resonant circuit; or one end of the leakage reactance L3 is connected with the positive electrode output end of the inverter bridge, the other end of the leakage reactance L3 is connected with the negative electrode output end of the inverter bridge, and the middle tap of the leakage reactance L3 is connected with the node O of the inverter bridge.

Optionally, the split parallel resonant inverter includes three connection modes, which are a first connection mode, a second connection mode and a third connection mode respectively;

The first connection mode comprises two modes, wherein one end of the leakage reactance L3 is connected with the positive electrode input end of the LC resonance circuit, the other end of the leakage reactance L3 is connected with the negative electrode input end of the LC resonance circuit, and a middle tap of the leakage reactance L3 is connected with a node D of the LC resonance circuit; or one end of the leakage reactance L3 is connected with the positive electrode output end of the inverter bridge, the other end of the leakage reactance L3 is connected with the negative electrode output end of the inverter bridge, and a middle tap of the leakage reactance L3 is connected with a node O of the inverter bridge;

The first connection mode is as follows: the other ends of the first switches S1 of all the positive modules are connected to the same copper bar to form a first output bus bar, the other ends of the fourth switches S4 of all the negative modules are connected to the same copper bar to form a second output bus bar, the other ends of the second switches S2 of all the positive modules are connected to the same copper bar to form a first bus bar, and the other ends of the third switches S3 of all the negative modules are connected to the same copper bar to form a second bus bar;

The first output bus bar is fixedly connected with the first copper bar through a connecting bolt, the second output bus bar is fixedly connected with the second copper bar through a connecting bolt, the first bus bar and the second bus bar are fixedly arranged on a first copper plate through connecting bolts, the first copper plate is a node O of the inverter bridge, and a 90-degree bent connecting copper plate is respectively arranged at the bolt connection positions of the first bus bar, the second bus bar and the first copper plate and used as a connecting point of the node O of the inverter bridge; one end of the capacitor C12 is fixedly connected with the first copper plate through a connecting bolt, the other end of the capacitor C12 is fixedly connected with one end of a second copper plate through a connecting bolt, and the other end of the second copper plate is fixedly connected with the first copper bar through a connecting bolt; one end of the capacitor C22 is fixedly connected with the first copper plate through a connecting bolt, the other end of the capacitor C22 is fixedly connected with one end of a third copper plate through a connecting bolt, and the other end of the third copper plate is fixedly connected with the second copper bar through a connecting bolt; a 90-degree bending copper bar is respectively arranged at the bolt connection position of the first copper bar and the first output bus bar and the bolt connection position of the second copper bar and the second output bus bar and used as an anode output end and a cathode output end of the inverter bridge;

One end of the first capacitor C1 is fixedly connected with the fourth copper plate through a connecting bolt, the other end of the first capacitor C1 is fixed with a fifth copper plate through a connecting bolt, one end of the fifth copper plate is bent and then is fixed with a third copper bar through a connecting bolt, and the other end of the fifth copper plate is fixedly connected with the third capacitor C3 through a copper plate with a concave structure and a connecting bolt; the third copper bar is also connected and fixed with a sixth copper plate through a connecting bolt, the sixth copper plate is of a 90-degree bending structure, and the extending part of the sixth copper plate is a connecting point of the positive electrode input end of the LC resonance circuit; one end of the second capacitor C2 is fixedly connected with the fourth copper plate through a connecting bolt, the other end of the second capacitor C2 is fixed with a seventh copper plate through a connecting bolt, one end of the seventh copper plate is fixed with a fourth copper bar through a connecting bolt after being bent, and the other end of the seventh copper plate is fixedly connected with the fourth capacitor C4 through a copper plate with a concave-shaped structure and a connecting bolt; the fourth copper bar is also connected and fixed with an eighth copper plate through a connecting bolt, the eighth copper plate is of a 90-degree bending structure, and the extending part of the eighth copper plate is a connecting point of the negative electrode input end of the LC resonance circuit;

The fourth copper plate is a node D of the LC resonant circuit, and two side positions, close to the third copper bar and the fourth copper bar, of the fourth copper plate are respectively connected and fixed with a connecting copper plate bent by 90 degrees by connecting bolts to serve as a connecting point of the node D of the LC resonant circuit;

Connecting the positive output end of the inverter bridge with the positive input end of the LC resonance circuit and the node O of the inverter bridge with the node D of the LC resonance circuit by adopting the twisted pair or the twisted pair cable or the coaxial cable or the shielding cable, and connecting the negative output end of the inverter bridge with the negative input end of the LC resonance circuit and the node O of the inverter bridge with the node D of the LC resonance circuit by adopting the other twisted pair or the twisted pair cable or the coaxial cable or the shielding cable;

the second connection mode comprises two modes, wherein one end of the leakage reactance L3 is connected with the positive electrode input end of the LC resonance circuit, the other end of the leakage reactance L3 is connected with the negative electrode input end of the LC resonance circuit, and a middle tap of the leakage reactance L3 is connected with a node D of the LC resonance circuit; or one end of the leakage reactance L3 is connected with the positive electrode output end of the inverter bridge, the other end of the leakage reactance L3 is connected with the negative electrode output end of the inverter bridge, and a middle tap of the leakage reactance L3 is connected with a node O of the inverter bridge;

The second connection mode is as follows: the other ends of the first switches S1 of all the positive modules are connected to the same copper bar to form a first output bus bar, the other ends of the fourth switches S4 of all the negative modules are connected to the same copper bar to form a second output bus bar, the other ends of the second switches S2 of all the positive modules are connected to the same copper bar to form a first bus bar, and the other ends of the third switches S3 of all the negative modules are connected to the same copper bar to form a second bus bar;

The first output bus bar is fixedly connected with the first copper bar through a connecting bolt, and the second output bus bar is fixedly connected with the second copper bar through a connecting bolt; the first bus bar and the second bus bar are fixed on the first copper plate through connecting bolts, and the first copper plate is a node O of the inverter bridge; one end of the capacitor C12 is fixedly connected with the first copper plate through a connecting bolt, the other end of the capacitor C12 is fixedly connected with the second copper plate through a connecting bolt, one end of the second copper plate is fixedly connected with the first copper bar through a connecting bolt after being bent, and the other end of the second copper plate is used as an anode output end of the inverter bridge after being bent; one end of the capacitor C22 is fixedly connected with the first copper plate through a connecting bolt, the other end of the capacitor C22 is fixedly connected with a third copper plate through a connecting bolt, one end of the third copper plate is fixedly connected with the second copper bar through a connecting bolt after being bent, and the other end of the third copper plate is used as a negative electrode output end of the inverter bridge after being bent;

One end of the first capacitor C1 is fixedly connected with the fourth copper plate through a connecting bolt, the other end of the first capacitor C1 is fixed with a fifth copper plate through a connecting bolt, one end of the fifth copper plate is fixed with a third copper bar through a connecting bolt after being bent, the other end of the fifth copper plate is fixedly connected with the third capacitor C3 through a copper plate with a concave structure and a connecting bolt, one end of a ninth copper plate is fixed with the third copper bar through a connecting bolt after being bent, and the other end of the ninth copper plate is used as an anode input end of the LC resonant circuit after being bent; one end of the second capacitor C2 is fixedly connected with the fourth copper plate through a connecting bolt, the other end of the second capacitor C2 is fixedly connected with a seventh copper plate through a connecting bolt, one end of the seventh copper plate is fixed with a fourth copper bar through a connecting bolt after being bent, the other end of the seventh copper plate is fixedly connected with the fourth capacitor C4 through a copper plate with a concave structure and a connecting bolt after being bent, one end of the tenth copper plate is fixed with the fourth copper bar through a connecting bolt after being bent, the other end of the tenth copper plate is used as a negative electrode input end of the LC resonance circuit after being bent, and the fourth copper plate is a node D of the LC resonance circuit;

the twisted pair or the twisted pair cable or the coaxial cable or the shielding cable is adopted to connect the positive electrode output end of the inverter bridge with the positive electrode input end of the LC resonance loop and connect the negative electrode output end of the inverter bridge with the negative electrode input end of the LC resonance loop; a single cable or a single wire is adopted to connect the node O of the inverter bridge with the node D of the LC resonant circuit;

The third connection mode comprises two modes, wherein one end of the leakage reactance L3 is connected with the positive electrode input end of the LC resonance circuit, the other end of the leakage reactance L3 is connected with the negative electrode input end of the LC resonance circuit, and a middle tap of the leakage reactance L3 is connected with a node D of the LC resonance circuit; or one end of the leakage reactance L3 is connected with the positive electrode output end of the inverter bridge, the other end of the leakage reactance L3 is connected with the negative electrode output end of the inverter bridge, and a middle tap of the leakage reactance L3 is connected with a node O of the inverter bridge;

The third connection mode is as follows: the other ends of the first switches S1 of all the positive modules are connected to the same copper bar to form a first output bus bar, the other ends of the fourth switches S4 of all the negative modules are connected to the same copper bar to form a second output bus bar, the other ends of the second switches S2 of all the positive modules are connected to the same copper bar to form a first bus bar, and the other ends of the third switches S3 of all the negative modules are connected to the same copper bar to form a second bus bar;

One end of the first capacitor C1 is fixedly connected with the fourth copper plate through a connecting bolt, the other end of the first capacitor C1 is fixed with a fifth copper plate through a connecting bolt, one end of the fifth copper plate is fixed with a third copper bar through a connecting bolt after being bent, the other end of the fifth copper plate is fixedly connected with the third capacitor C3 through a copper plate with a concave structure and a connecting bolt, one end of a ninth copper plate is fixed with the third copper bar through a connecting bolt after being bent, and the other end of the ninth copper plate is used as an anode input end of the LC resonant circuit after being bent; one end of the second capacitor C2 is fixedly connected with the fourth copper plate through a connecting bolt, the other end of the second capacitor C2 is fixedly connected with the seventh copper plate through a connecting bolt, one end of the seventh copper plate is fixed with the fourth copper bar through a connecting bolt after being bent, the other end of the seventh copper plate is fixedly connected with the fourth capacitor C4 through a copper plate with a concave structure and a connecting bolt after being bent, one end of the tenth copper plate is fixedly connected with the fourth copper bar through a connecting bolt after being bent, the other end of the tenth copper plate is used as a negative electrode input end of the LC resonant circuit after being bent, and the fourth copper plate is a node D of the LC resonant circuit;

And connecting the positive electrode output end of the inverter bridge with the positive electrode input end of the LC resonance circuit and connecting the negative electrode output end of the inverter bridge with the negative electrode input end of the LC resonance circuit by adopting the twisted pair or the twisted pair cable or the coaxial cable or the shielding cable.

Optionally, the connecting bolt is a copper bolt or an austenitic stainless steel bolt.

Optionally, the inductance network is formed by a seventh inductance L7 or formed by connecting a fifth inductance L5, a seventh inductance L7 and a sixth inductance L6 in series and then connecting the fifth inductance L5, the seventh inductance L7 and the sixth inductance L6 in parallel with a fourth inductance L4;

when the inductance network is formed by connecting a fifth inductance L5, a seventh inductance L7 and a sixth inductance L6 in series and then connecting the fifth inductance L5 and the sixth inductance L4 in parallel, the connection end of the fourth inductance L4 and the fifth inductance L5 is the positive input end of the inductance network, the other end of the fifth inductance L5 is connected with one end of the seventh inductance L7, the other end of the seventh inductance L7 is connected with one end of the sixth inductance L6, and the connection end of the fourth inductance L4 and the sixth inductance L6 is the negative input end of the inductance network.

Optionally, the fourth inductor L4 is a frequency adjusting inductor, the seventh inductor L7 is an equivalent inductor of a load inductor, a transformer or an electrode, the fifth inductor L5 and the sixth inductor L6 are current adjusting inductors, and the inductance of the fifth inductor L5 and the inductance of the sixth inductor L6 are equal.

Optionally, the number of the twisted pairs and the twisted pairs of the twisted pair cable, and the number of the coaxial cables and the number of the shielding cables are determined according to actual requirements.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

The invention provides a split type parallel resonant inverter formed by double-T topology inverter bridges, which comprises an inverter bridge, an LC resonant circuit, a leakage reactance L3, a capacitor C12, a capacitor C22 and a soft connection structure; the flexible connection structure comprises twisted pair wires, twisted pair cables, coaxial cables and shielding cables; the inverter bridge is of a double T-shaped topological structure which is vertically symmetrical; the inverter bridge consists of a first boost inductor L1, a positive module, a second boost inductor L2 and a negative module, wherein the output end of the positive module is the positive output end of the inverter bridge, and the output end of the negative module is the negative output end of the inverter bridge; the LC resonant circuit is of a topological structure which is vertically symmetrical; the LC resonance loop is formed by connecting an inductance network with a capacitor group formed by connecting a third capacitor C3, a first capacitor C1, a second capacitor C2 and a fourth capacitor C4 in series, wherein the capacitance of the first capacitor C1 is equal to that of the second capacitor C2, and the capacitance of the third capacitor C3 is equal to that of the fourth capacitor C4; the capacitance C12 is equal to the capacitance C22, and the capacitance C12 is smaller than the capacitance C1, and the capacitance C22 is smaller than the capacitance C2; the capacitor C12 is connected between the positive electrode output end of the inverter bridge and the node O of the inverter bridge, and the capacitor C22 is connected between the node O of the inverter bridge and the negative electrode output end of the inverter bridge; the node O is a floating zero voltage reference point of the inverter bridge; in actual use, the soft connection structure is used for connecting the positive electrode output end of the inverter bridge with the positive electrode input end of the LC resonance circuit and connecting the negative electrode output end of the inverter bridge with the negative electrode input end of the LC resonance circuit so as to realize an inversion function.

The invention sets the optimal split implementation point between the output end of the inverter bridge and the input end of the LC resonant circuit, and has the advantages of minimizing the current flowing through the flexible connector, minimizing the loss and the like compared with other split implementation points, such as in the LC resonant circuit or in an inductance network.

The invention eliminates the adverse effect of distributed inductance existing in connecting wires on voltage waveforms at two ends of a bridge arm of an inverter bridge through arranging the capacitor C12, the capacitor C22 and the soft connecting structure, realizes the split arrangement of the inverter bridge and the LC resonant circuit in the inverter, and meets the use requirements of the inverter or an induction heating power supply formed by the inverter in different induction heating processes and different heating occasions.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of a topology of a conventional parallel resonant inverter formed by a double-T topology inverter bridge; (hereinafter referred to as the topology of the inverter);

fig. 2 is a schematic diagram of a topology structure of an inverter after the inductor network 6 in fig. 1 is equivalent to the inductor L8;

FIG. 3 is a schematic diagram of a prior art integrated, compact assembly of a parallel resonant inverter comprised of a double-T topology inverter bridge;

fig. 4 is a topology diagram of an inverter according to an embodiment of the present invention after capacitor C12 is decomposed from capacitor C1 and capacitor C22 is decomposed from capacitor C2;

FIG. 5 is a schematic diagram illustrating the connection of the leakage reactance L3 to the input side of the LC resonant tank in the first connection mode according to the embodiment of the present invention;

fig. 6 is a schematic connection diagram of the leakage reactance L3 installed on the output side of the inverter bridge in the first connection mode according to the embodiment of the present invention;

FIG. 7 is a schematic diagram showing a second embodiment of the present invention in which a leakage reactance L3 is installed on the input side of an LC tank;

Fig. 8 is a schematic connection diagram of the leakage reactance L3 installed on the output side of the inverter bridge in the second connection mode according to the embodiment of the present invention;

Fig. 9 is a schematic diagram of a topology structure of an inverter with a leakage reactance L3 connected to an input side of an LC tank circuit after an OD connection line is removed in a third connection manner according to an embodiment of the present invention;

FIG. 10 is a schematic diagram of a third embodiment of the present invention, in which the leakage reactance L3 is installed on the input side of the LC tank after the OD connection line is removed;

fig. 11 is a schematic diagram of a topology structure of an inverter with a leakage reactance L3 connected to an output side of an inverter bridge after an OD connection line is removed in a third connection manner according to an embodiment of the present invention;

fig. 12 is a schematic diagram of a third connection mode according to the embodiment of the present invention, in which the leakage reactance L3 is installed on the output side of the inverter bridge after the OD connection line is removed.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In order to solve the defects in the background technology existing in practical application, the invention provides a split type parallel resonant inverter formed by double-T-shaped topological inverter bridges, solves the problems that the electric characteristics of the inverter are influenced by distributed inductance between the inverter bridge and the LC resonant circuit because copper polar plates are required to be integrally and compactly assembled between the inverter bridge and the LC resonant circuit, and basically does not increase current loss on the premise that the distributed inductance between the inverter bridge and the LC resonant circuit does not obviously influence the electric characteristics of the inverter, and can lead out the LC resonant circuit for a plurality of meters under the condition that the overall efficiency is basically not reduced, thereby truly solving the problems of increased cable inductance, large current loss, seriously reduced overall efficiency and the like caused by the fact that a single-junction inductor (or electrode) is required to be connected by a very thick water-cooled cable, and meeting the use requirements of the inverter or an induction heating power supply formed by the inverter in different induction heating processes and different heating occasions.

In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.

Fig. 1 is a schematic diagram of a topology of a conventional parallel resonant inverter formed by a double-T topology inverter bridge; (hereinafter referred to as the topology of the inverter); fig. 2 is a schematic diagram of a topology structure of an inverter after the inductor network 6 in fig. 1 is equivalent to the inductor L8; fig. 3 is a schematic diagram of a conventional integrated, compact assembly structure of a parallel resonant inverter consisting of a double-T topology inverter bridge.

The parallel resonant inverter formed by the double-T topology inverter bridge mainly comprises an inverter bridge 1 and an LC resonant loop 4.

As shown in fig. 1, the left side is an inverter bridge 1 and the right side is an LC tank 4, bounded by dashed lines P1-P2.

The inverter bridge 1 is of a double T-shaped topological structure which is vertically symmetrical; the inverter bridge 1 is composed of a first boost inductor L1, a positive module 2, a second boost inductor L2 and a negative module 3, wherein the output end of the positive module 2 is the positive output end of the inverter bridge 1, and the output end of the negative module 3 is the negative output end of the inverter bridge 1. The number of positive modules 2 and negative modules 3 is determined according to the actual power output power requirements.

The positive module 2 is composed of a first bridge arm A+ and a second bridge arm B+; the first bridge arm a+ is formed by a first switch S1. The second bridge arm B+ is composed of a second switch S2; the negative module 3 consists of a first bridge arm A-and a second bridge arm B-; the first bridge arm A-is composed of a fourth switch S4; the second leg B-is formed by a third switch S3. The first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are all parallel groups of a plurality of switch units formed by power switch components.

One end of the first switch S1 of the positive module 2 is connected with one end of the second switch S2, the common end of the first switch S1 and the second switch S2 is a direct current input positive end E of the positive module 2, the direct current input positive end E is further connected with one end of the first boost inductor L1, and the other end of the first boost inductor L1 is connected with the positive electrode of the direct current voltage Ud.

One end of a third switch S3 of the negative module 3 is connected with one end of a fourth switch S4, the common end of the third switch S3 and the fourth switch S4 is a direct current input negative end F of the negative module 3, the direct current input negative end F is also connected with one end of a second boost inductor L2, and the other end of the second boost inductor L2 is connected with the negative electrode of the direct current voltage Ud.

The other end K of the second switch S2 of the positive module 2 and the other end U of the third switch S3 of the negative module 3 are connected together to form a node O. The other end J of the first switch S1 of the positive module 2 and the other end W of the fourth switch S4 of the negative module 3 are respectively the positive electrode output end J and the negative electrode output end W of the inverter bridge 1 formed by the double-T topology.

The first boost inductor L1 and the first switch S1 and the second switch S2 of the positive module 2 form a T-shaped topology structure, and the second boost inductor L2 and the fourth switch S4 and the third switch S3 of the negative module 3 form a T-shaped topology structure, namely a double T-shaped topology structure. Due to the up-down symmetry of the double T topology, node O is the floating zero voltage reference point of the inverter bridge 1.

The LC resonance loop 4 is of a topology structure which is symmetrical up and down; the LC resonant circuit 4 is formed by connecting an inductance network 6 in parallel with a capacitor group formed by connecting a third capacitor C3, a first capacitor C1, a second capacitor C2 and a fourth capacitor C4 in series, wherein the first capacitor C1 and the second capacitor C2 are both capacitor parallel groups formed by a plurality of capacitors, and the capacitance of the first capacitor C1 is equal to that of the second capacitor C2; the third capacitor C3 and the fourth capacitor C4 are each a parallel capacitor group formed by a plurality of capacitors or a series connection of parallel capacitor groups formed by a plurality of capacitors, and the capacitance of the third capacitor C3 is equal to that of the fourth capacitor C4.

The positive electrode input end Y of the inductance network 6 is connected with one end of a third capacitor C3, the other end of the third capacitor C3 is connected with one end H of a first capacitor C1, and the other end of the first capacitor C1 is connected with one end of a second capacitor C2; a node D is arranged between the first capacitor C1 and the second capacitor C2; the other end N of the second capacitor C2 is connected with one end of the fourth capacitor C4, and the other end of the capacitor C4 is connected with the negative electrode input end Z of the inductance network 6.

The connection point of the first capacitor C1 and the third capacitor C3 is the positive input end of the LC resonant tank 4; the connection point of the second capacitor C2 and the fourth capacitor C4 is the negative input end of the LC resonant tank 4.

The inductance network 6 is configured by a seventh inductance L7 or by a fifth inductance L5, a seventh inductance L7, and a sixth inductance L6 connected in series and then connected in parallel with a fourth inductance L4.

The inductance network 6 is composed of a seventh inductance L7, and two ends of the seventh inductance L7 are respectively a positive electrode input end Y and a negative electrode input end Z of the inductance network.

When the inductance network 6 is formed by connecting a fifth inductance L5, a seventh inductance L7 and a sixth inductance L6 in series and then connecting the fifth inductance L5 and the fourth inductance L4 in parallel, the connection end of the fourth inductance L4 and the fifth inductance L5 is the positive input end Y of the inductance network, the other end of the fifth inductance L5 is connected with one end of the seventh inductance L7, the other end of the seventh inductance L7 is connected with one end of the sixth inductance L6, and the connection end of the fourth inductance L4 and the sixth inductance L6 is the negative input end Z of the inductance network. The fourth inductor L4 is a frequency adjusting inductor, the fifth inductor L5 and the sixth inductor L6 are current adjusting inductors, and the seventh inductor L7 is a load inductor or a transformer or an equivalent inductor of an electrode. The inductance of the fifth inductance L5 and the sixth inductance L6 are equal.

Due to the symmetry of the LC tank 4 above and below the topology, node D is the floating zero potential reference point of the LC tank 4.

The parallel resonant inverter further includes a leakage reactance L3, indicated by reference numeral 5; one end of the leakage reactance L3 is connected with the input end node H of the LC resonant circuit 4, the other end of the leakage reactance L3 is connected with the input end node N of the LC resonant circuit 4, and the intermediate tap of the leakage reactance L3 is connected with the node D. Or one end of the leakage reactance L3 is connected with the positive electrode output end J of the inverter bridge 1, the other end of the leakage reactance L3 is connected with the negative electrode output end W of the inverter bridge 1, and a middle tap of the leakage reactance L3 is connected with the node O of the inverter bridge 1.

The leakage reactance L3 has an inductance that is several tens of times larger than the inductance of the inductance network L8, and is mainly used to provide a path for a dc component formed in the resonant tank due to the asymmetry of the switching time of the inverter bridge, and the leakage reactance L3 is generally referred to as a dc leakage reactance.

For convenience in description and drawing of the embodiment, the inductance network 6 in fig. 1 may be equivalent to an inductance element L8, denoted by reference numeral 6; the ends Y, Z of the inductance L8 are equivalent to the ends Y, Z of the inductance network 6, as shown in fig. 2.

A schematic diagram of a conventional integrated compact assembly structure of a parallel resonant inverter consisting of a double-T topology inverter bridge is shown in fig. 3.

In order to solve the problem that the electric characteristics of the inverter are influenced by the distributed inductance of a connector between an inverter bridge and an LC resonant circuit of a parallel resonant inverter consisting of double-T-shaped topological inverter bridges, the inverter bridge and the LC resonant circuit of the existing parallel resonant inverter are required to be integrally and compactly assembled by adopting copper polar plates. The invention improves on the prior art provided by fig. 2 or 3, and provides a split parallel resonant inverter formed by double-T-shaped topological inversion bridges, the principle of which is shown in fig. 4, on the basis of the topological structure of the parallel resonant inverter formed by double-T-shaped topological inversion bridges shown in fig. 2, a part of capacitors C12 in a first capacitor C1 are connected in parallel with the first capacitor C1, a part of capacitors C22 in a second capacitor C2 are connected in parallel with the second capacitor C2, and the capacitance of the capacitors C12 is equal to the capacitance of the capacitors C22, so that the adverse effect on the voltage waveforms at two ends of an inversion bridge arm due to the distributed inductance existing in connecting wires is eliminated on the basis of not changing the basic topological structure of the inverter. On the basis of the topology shown in fig. 4, the connections between the output J, the output W and the node O of the inverter bridge 1 and the input H, the input N and the node D of the LC tank 4 are implemented by means of soft connections.

Based on the principle, the split parallel resonant inverter mainly comprises an inverter bridge, an LC resonant circuit, a capacitor C12, a capacitor C22, a leakage reactance L3 and a soft connection structure. The capacitor C12 is connected between the positive output terminal J of the inverter bridge 1 and the node O of the inverter bridge 1, and the capacitor C22 is connected between the node O of the inverter bridge 1 and the negative output terminal W of the inverter bridge.

The capacitor C12 and the capacitor C22 are connected in parallel and are formed by one or more capacitors, and the capacitance of the capacitor C12 is equal to the capacitance of the capacitor C22. The ratio of the capacitance of the capacitor C12, the first capacitance C1, the capacitance of the capacitor C22, and the capacitance of the second capacitance C2 is C12: c1 =c22: c2 =1:5 to 1:10.

The flexible connection structure includes twisted pair, twisted pair cable, coaxial cable and shielded cable.

In order to meet the actual power output requirement, the number of blocks of the positive module 2 and the negative module 3 is plural, in which case the flexible connection structure includes plural twisted pairs, plural coaxial cables and plural shielded cables.

Three connection modes are provided in the embodiment of the invention. The leakage reactance L3 can be arranged on the input side of the LC resonant circuit 4 or on the output side of the inverter bridge 1, namely one end of the leakage reactance L3 is connected with the positive input end H of the LC resonant circuit 4, the other end of the leakage reactance L3 is connected with the negative input end N of the LC resonant circuit 4, and a middle tap of the leakage reactance L3 is connected with the node D of the LC resonant circuit 4; or one end of the leakage reactance L3 is connected with the positive output end J of the inverter bridge 1, the other end of the leakage reactance L3 is connected with the negative output end W of the inverter bridge 1, and the middle tap of the leakage reactance L3 is connected with the node O of the inverter bridge 1, so that each connection mode has two types.

First connection mode

The positive electrode output end J and the negative electrode output end W of the inverter bridge 1 and the positive electrode input end H and the negative electrode input end N of the LC resonant circuit 4 are respectively connected with the suspension zero voltage reference point OD line in a twisted pair mode by adopting a connecting wire JH line and a connecting wire WN line, or are connected with the same coaxial cable or the same shielding cable by adopting the connecting wire JH line and the same OD line, and the connecting wire WN line and the OD line are connected with the other coaxial cable or the same shielding cable. In addition, according to the actual demand, in order to meet the requirement of a certain current value, the positive electrode output end J and the negative electrode output end W of the inverter bridge 1 and the positive electrode input end H and the negative electrode input end N of the LC resonant circuit 4 are respectively connected in a manner of adopting a plurality of twisted pairs, a plurality of twisted pairs of cables, a plurality of coaxial cables or a plurality of shielding cables, so as to increase the sectional area of the wires and improve the conductivity.

As shown in fig. 5, in the actual assembly, the other ends of the first switches S1 of all the positive modules 2 are all connected to the same copper bar to form a first output bus bar, the other ends of the fourth switches S4 of all the negative modules 3 are all connected to the same copper bar to form a second output bus bar, the other ends of the second switches S2 of all the positive modules 2 are all connected to the same copper bar to form a first bus bar, and the other ends of the third switches S3 of all the negative modules 3 are all connected to the same copper bar to form a second bus bar.

The end E of the positive module 2 is one end of a direct current positive input bus bar, the end J is one end of a first output bus bar of a first bridge arm A+ and the end K is one end of a first bus bar of a second bridge arm B+. The end F of the negative module 3 is one end of a direct current negative electrode input busbar, the end W is one end of a second output busbar of the first bridge arm A-, and the end U is one end of a first busbar of the second bridge arm B-. The first output busbar is fixedly connected with the first copper bar 11 through a connecting bolt. Likewise, the second output bus bar is fixedly connected with the second copper bar 12 by a connecting bolt. The first busbar and the second busbar are fixed on a first copper plate 21 through connecting bolts, and the first copper plate 21 is a floating zero potential reference point O point of the inverter bridge 1. A 90-degree bent copper plate is respectively arranged at the bolt connection points of the first bus bar, the second bus bar and the first copper plate 21 as a connection point of a node O of the inverter bridge 1.

One end of the capacitor C12 is fixedly connected with the first copper plate 21 through a connecting bolt, the other end of the capacitor C12 is fixedly connected with one end of the second copper plate 22 through a connecting bolt, and the other end of the second copper plate 22 is fixedly connected with the first copper bar 11 and the first output bus bar through the connecting bolt; one end of the capacitor C22 is fixedly connected with the first copper plate 21 through a connecting bolt, the other end of the capacitor C22 is fixedly connected with one end of the third copper plate 23 through a connecting bolt, and the other end of the third copper plate 23 is fixedly connected with the second copper bar 12 and the second output bus bar through connecting bolts. And a 90-degree bending copper bar is respectively arranged at the bolt connection position of the first copper bar 11 and the first output bus bar and the bolt connection position of the second copper bar 12 and the second output bus bar to serve as an anode output end and a cathode output end of the inverter bridge.

One end of the first capacitor C1 is fixedly connected with the fourth copper plate 24 through a connecting bolt, the other end of the first capacitor C1 is fixedly connected with the fifth copper plate 25 through a connecting bolt, one end of the fifth copper plate 25 is bent and then is fixed with the third copper bar 13 through a connecting bolt, and the fifth copper plate 25 is fixedly connected with one end of the third capacitor C3 through a copper plate with a concave structure and a connecting bolt; the third copper bar 13 is further connected and fixed with a sixth copper plate 26 through a connecting bolt, the sixth copper plate 26 is of a 90-degree bending structure, and an extending portion of the sixth copper plate 26 is a connecting point of the positive electrode input end H of the LC resonance circuit.

One end of the second capacitor C2 is fixedly connected with the fourth copper plate 24 through a connecting bolt, the other end of the second capacitor C2 is fixedly connected with the seventh copper plate 27 through a connecting bolt, one end of the seventh copper plate 27 is bent and then is fixed with the fourth copper bar 14 through a connecting bolt, and the other end of the seventh copper plate 27 is fixedly connected with one end of the fourth capacitor C4 through a copper plate with a concave structure and a connecting bolt; the fourth copper bar 14 is further connected and fixed with an eighth copper plate 28 through a connecting bolt, the eighth copper plate 28 is in a 90-degree bending structure, and an extending portion of the eighth copper plate 28 is a connecting point of a negative electrode input end of the LC resonant circuit.

The fourth copper plate 24 is a floating zero potential reference point D of the LC resonant circuit 4, and two side positions, close to the third copper bar 13 and the fourth copper bar 14, of the fourth copper plate 24 are respectively connected and fixed with a connecting copper plate bent by 90 degrees by using connecting bolts to serve as a connecting point of a node D of the LC resonant circuit 4.

The other end of the third capacitor C3 is fixedly connected with the eleventh copper plate 31 through a connecting bolt, and the eleventh copper plate 31 is fixedly connected with the Y end of the inductance network L8 through the connecting bolt after being bent by 90 degrees. The other end of the third capacitor C4 is fixedly connected with the twelfth copper plate 32 through a connecting bolt, and the twelfth copper plate 32 is fixedly connected with the Z end of the inductance network L8 through the connecting bolt after being bent for 90 degrees.

The adjacent portions between the fifth copper plate 25 and the seventh copper plate 27, and the adjacent portions between the eleventh copper plate 31 and the twelfth copper plate 32 are each separated by a polytetrafluoroethylene insulating plate to achieve an insulating treatment.

The positive output terminal J of the inverter bridge 1 is connected with the positive input terminal H of the LC resonant tank 4, and the node O of the inverter bridge 1 is connected with the node D of the LC resonant tank 4 by twisted pair, coaxial cable or shielded cable, as indicated by the reference numeral 15 in fig. 5. Likewise, twisted pair, coaxial cable or shielded cable is used to connect the negative output terminal W of the inverter bridge 1 with the negative input terminal N of the LC tank 4, and the node O of the inverter bridge 1 with the node D of the LC tank 4, as indicated by reference numeral 16 in fig. 5.

In this connection mode, the leakage reactance L3 has two installation modes at different positions, the leakage reactance L3 is installed at the input side of the LC resonant tank 4, as shown in fig. 5, two ends of the leakage reactance L3 are respectively connected and fixed with the third copper bar 13 and the fourth copper bar 14 by connecting bolts, and a center tap of the leakage reactance L3 is connected and fixed with the fourth copper plate 24 by connecting bolts.

The leakage reactance L3 is mounted on the output side of the inverter bridge 1, and as shown in fig. 6, both ends of the leakage reactance L3 are respectively connected and fixed with the first copper bar 11 and the second copper bar 12 by connecting bolts, and a center tap of the leakage reactance L3 is connected and fixed with the first copper plate 21 by connecting bolts.

Second connection mode

The positive electrode output end J and the negative electrode output end W of the inverter bridge 1 are connected with the positive electrode input end H and the negative electrode input end N of the LC resonant circuit 4 in a twisted pair mode by adopting a connecting wire JH line and a connecting wire WN line, or in a mode that the connecting wire JH line and the connecting wire WN line are the same coaxial cable, or in a mode that the connecting wire JH line and the connecting wire WN line are the same shielding cable. The connection OD line between the suspension zero voltage reference point node O of the inverter bridge 1 and the suspension zero potential reference point node D of the LC resonant circuit 4 adopts a mode of connecting by a single cable.

On the basis, according to the actual demand, in order to meet the requirement of a certain current value, the positive electrode output end J, the negative electrode output end W of the inverter bridge 1 and the positive electrode input end H and the negative electrode input end N of the LC resonant circuit 4 are connected by adopting a plurality of twisted pairs or twisted pairs of cables and adopting a plurality of coaxial cables or a plurality of shielding cables so as to increase the sectional area of the lead and improve the conductivity,

A second connection according to the topology described in fig. 4 is shown in fig. 7. The assembly structure is different from that of fig. 5 in that the shapes of the second copper plate 22 and the third copper plate 23 on the output side of the inverter bridge 1 are changed, and a ninth copper plate 29 and a tenth copper plate 30 on the input side of the LC resonant tank 4 are additionally arranged, and the assembly structure and the manner of other parts are the same as those of fig. 5.

As shown in fig. 7, the other ends of the first switches S1 of all the positive modules 2 are all connected to the same copper bar to form a first output bus bar, the other ends of the fourth switches S4 of all the negative modules 3 are all connected to the same copper bar to form a second output bus bar, the other ends of the second switches S2 of all the positive modules 2 are all connected to the same copper bar to form a first bus bar, and the other ends of the third switches S3 of all the negative modules 3 are all connected to the same copper bar to form a second bus bar.

The end E of the positive module 2 is one end of a direct current positive input bus bar, the end J is one end of a first output bus bar of a first bridge arm A+ and the end K is one end of a first bus bar of a second bridge arm B+. The end F of the negative module 3 is one end of a direct current negative electrode input busbar, the end W is one end of a second output busbar of the first bridge arm A-, and the end U is one end of a first busbar of the second bridge arm B-.

The first output busbar is fixedly connected with the first copper bar 11 through a connecting bolt. Likewise, the second output bus bar is fixedly connected with the second copper bar 12 by a connecting bolt. The first busbar and the second busbar are fixed on a first copper plate 21 through connecting bolts, and the first copper plate 21 is a floating zero potential reference point O point of the inverter bridge 1. One end of the capacitor C12 is fixedly connected with the first copper plate 21 through a connecting bolt, the other end of the capacitor C12 is fixedly connected with the second copper plate 22 through a connecting bolt, one end of the second copper plate 22 is fixedly connected with the first copper bar 11 through the connecting bolt after being bent for 90 degrees twice, and the other end of the second copper plate 22 is bent for 90 degrees and then serves as the positive electrode output end J of the inverter bridge 1.

One end of the capacitor C22 is fixedly connected with the first copper plate 21 through a connecting bolt, the other end of the capacitor C22 is fixedly connected with one end of the third copper plate 23 through a connecting bolt, one end of the third copper plate 23 is fixedly connected with the second copper bar 12 through a connecting bolt after being bent for 90 degrees twice, and the other end of the third copper plate 23 is bent for 90 degrees and then serves as a negative electrode output end W of the inverter bridge 1.

One end of the first capacitor C1 is fixedly connected with the fourth copper plate 24 through a connecting bolt, the other end of the first capacitor C1 is fixedly connected with the fifth copper plate 25 through a connecting bolt, one end of the fifth copper plate 25 is fixedly connected with the third copper bar 13 through a connecting bolt after being bent, the other end of the fifth copper plate 25 is fixedly connected with one end of the third capacitor C3 through a copper plate with a concave structure and a connecting bolt, one end of the ninth copper plate 29 is fixedly connected with the third copper bar 13 through a connecting bolt after being bent for 90 degrees twice, and the other end of the ninth copper plate 29 is bent for 90 degrees and then used as the positive electrode input end H of the LC resonant circuit 4.

One end of the second capacitor C2 is fixedly connected with the fourth copper plate 24 through a connecting bolt, the other end of the second capacitor C2 is fixedly connected with the seventh copper plate 27 through a connecting bolt, one end of the seventh copper plate 27 is fixedly connected with the fourth copper bar 14 through a connecting bolt after being bent, and the other end of the seventh copper plate 27 is fixedly connected with one end of the fourth capacitor C4 through a copper plate with a concave structure and a connecting bolt; one end of the tenth copper plate 30 is bent for 90 degrees twice and then is connected and fixed with the fourth copper bar 14 through a connecting bolt, and the other end of the tenth copper plate 30 is bent for 90 degrees and then is used as a negative electrode input end N of the LC resonant circuit 4. The fourth copper plate 24 is the node D of the LC tank 4.

The other end of the third capacitor C3 is fixedly connected with the eleventh copper plate 31 through a connecting bolt, and the eleventh copper plate 31 is fixedly connected with the Y end of the inductance network L8 through the connecting bolt after being bent by 90 degrees. The other end of the fourth capacitor C4 is fixedly connected with the twelfth copper plate 32 through a connecting bolt, and the twelfth copper plate 32 is fixedly connected with the Z end of the inductance network L8 through the connecting bolt after being bent for 90 degrees.

The positive electrode output end J of the inverter bridge 1 is connected with the positive electrode input end H of the LC resonant circuit 4, and the negative electrode output end W of the inverter bridge 1 is connected with the negative electrode input end N of the LC resonant circuit 4 by adopting twisted pair cables, coaxial cables or shielded cables, as shown by reference numeral 41 in fig. 7; a single cable is used to connect node O of inverter bridge 1 with node D of LC tank 4, as shown by single cable 42 in fig. 7.

In this connection, the leakage reactance L3 has two installation forms at different positions, the leakage reactance L3 is installed at the input side of the LC tank 4, as shown in fig. 7, two ends of the leakage reactance L3 are respectively connected and fixed with the third copper bar 13 and the fourth copper bar 14 by connection bolts, and a center tap of the leakage reactance L3 is connected and fixed with the fourth copper plate 24 by connection bolts.

As shown in fig. 8, the connection schematic diagram of the leakage reactance L3 installed on the output side of the inverter bridge 1 is that two ends of the leakage reactance L3 are respectively connected and fixed with the first copper bar 11 and the second copper bar 12 by connection bolts, and a center tap of the leakage reactance L3 is connected and fixed with the first copper plate 21 by connection bolts.

Third connection mode

In the second connection mode, as the double-T-shaped topological inverter bridge structure is in vertical symmetry, the node O is a floating zero voltage reference point of the inverter bridge 1. The LC resonant tank 4 also has up-down symmetry in the topology structure, the node D is a floating zero potential reference point of the LC resonant tank 4, and the potential of the node O is equal to that of the node D objectively, so that the node O and the node D can not be connected, the working state of the inverter can not be affected after the OD connecting wire is removed, and the topology structure schematic diagram of the inverter with the leakage reactance L3 connected to the input side of the LC resonant tank 4 shown in fig. 9 and the topology structure schematic diagram of the inverter with the leakage reactance L3 connected to the output side of the inverter bridge 1 shown in fig. 11 are obtained after the OD connecting wire is removed. A schematic connection diagram of the leakage reactance L3 shown in fig. 10 installed on the input side of the LC tank 4, and a schematic connection diagram of the leakage reactance L3 shown in fig. 12 installed on the output side of the inverter bridge 1.

A schematic diagram of inverter connection based on the topology shown in fig. 9 is shown in fig. 10. Exactly the same as in fig. 7 in the assembled structure, the leakage reactance L3 is installed on the input side of the LC tank 4.

As shown in fig. 10, the positive output terminal J and the negative output terminal W of the inverter bridge 1 are connected to the positive input terminal H and the negative input terminal N of the LC tank 4 by twisting the connection line JH and the WN line, by using the same coaxial cable as the connection line JH and the WN line, or by using the same shielded cable as the connection line JH and the WN line. On the basis, in order to meet the requirement of a certain current value, the positive electrode output end J and the negative electrode output end W of the inverter bridge 1 are connected with the positive electrode input end H and the negative electrode input end N of the LC resonant circuit 4 by adopting a mode of adopting a plurality of twisted pairs or a plurality of twisted pairs of cables or adopting a plurality of coaxial cables or a plurality of shielding cables. As shown by twisted pair 41 in fig. 10.

An inverter connection schematic diagram based on the topology shown in fig. 11 is shown in fig. 12. Exactly the same as fig. 8 in the assembled structure, the leakage reactance L3 is installed on the inverter bridge 1 side.

As shown in fig. 12, the positive output terminal J and the negative output terminal W of the inverter bridge 1 are connected to the positive input terminal H and the negative input terminal N of the LC tank 4 by twisting the connection line JH and the WN line, by using the same coaxial cable as the connection line JH and the WN line, or by using the same shielded cable as the connection line JH and the WN line. On the basis, in order to meet the requirement of a certain current value, the positive electrode output end J and the negative electrode output end W of the inverter bridge 1 are connected with the positive electrode input end H and the negative electrode input end N of the LC resonant circuit 4 by adopting a mode of adopting a plurality of twisted pairs or a plurality of twisted pairs of cables or adopting a plurality of coaxial cables or a plurality of shielding cables. As shown by twisted pair 41 in fig. 12.

The invention realizes split connection between the inverter bridge and the LC resonant circuit formed by double-T topology, and the output current of the inverter bridge is 1/Q times of the current of the LC resonant circuit, namely 1/Q times of the resonant current flowing through the inductor L7, namely the current output by the inverter bridge to the LC resonant circuit is far smaller than the resonant current (alternating current flowing through the seventh inductor L7) of the LC resonant circuit. Therefore, the split connection between the inverter bridge and the LC resonant circuit is easier to realize than the separate connection of the seventh inductor L7, and the inverter has the advantages of small current consumption, high overall efficiency of the inverter and the like, and the flexible connection is easy to realize due to the thin wires used for the small current.

In theory, the distributed inductance on the connecting lead in split connection can seriously affect the electric characteristics of the inverter and the voltage waveforms at two ends of the power switch device, and can cause the problems of breakdown, inverter damage and the like caused by overvoltage born by the power switch device, so that the inverter cannot normally work.

In order to realize the split connection mode between the inversion bridge and the LC resonant circuit, the invention adopts the measures that twisted pair or twisted pair cable or coaxial cable or shielding cable are adopted to connect the two, and the invention aims at reducing the influence caused by the inductance of the connecting lead to the minimum; meanwhile, a small part of capacitor C12 and capacitor C22 are separated from a first capacitor C1 and a second capacitor C2 in the LC resonant circuit and are arranged on the output side of the inverter bridge, namely, two output ends of the inverter bridge and a floating zero voltage reference point are respectively arranged, the capacitor C12 and the capacitor C22 have the functions of filtering counter-potential formed by the inductance of the connecting wire, and the counter-potential formed by the inductance of the connecting wire is prevented from causing adverse effect on the inverter bridge.

In summary, the invention solves the problems that in the prior parallel resonant inverter formed by double-T topology inverter bridge, in order to avoid the influence of the distributed inductance of the connector between the inverter bridge and the LC resonant circuit on the electrical characteristics of the inverter, copper polar plates are required to be adopted for integral and compact structural assembly form between the inverter bridge and the LC resonant circuit, the split connection between the inverter bridge and the LC resonant circuit and the soft connection mode are realized, the LC resonant circuit can be led out for a plurality of meters away under the conditions of basically not increasing current loss and basically not reducing the overall efficiency, and the technical problems that a single outgoing inductor or a heating electrode is required to be connected by a thick water-cooled cable, so that the inductance of the connecting cable is increased, the current loss is large, the overall efficiency is seriously reduced, and the practical application requirements can not be met are solved.

In addition, the split connection can be carried out between the double-T-shaped topological inversion bridge and the LC resonant circuit, the parallel resonant inverter is divided into the front-end large-volume device and the rear-end small-volume device, the remote installation of the front-end large-volume device of the parallel resonant inverter is realized, and the rear-end small-volume device can be conveniently installed and used even in the occasions of large induction heating or welding objects, complex structure and small working space due to small occupied space, so that the use requirements of the inverter or an induction heating power supply formed by the inverter in the application of different induction heating processes and different heating occasions are truly met.

The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.

Claims

1. The split type parallel resonant inverter formed by double-T-shaped topological inversion bridges is characterized by comprising an inversion bridge, an LC resonant circuit, a leakage reactance L3, a capacitor C12, a capacitor C22 and a soft connection structure; the flexible connection structure comprises twisted pair wires, twisted pair cables, coaxial cables and shielding cables;

the number of the positive modules and the negative modules is determined according to the actual power output power requirement;

The connection point between the first capacitor C1 and the second capacitor C2 is a node D; the connection point of the first capacitor C1 and the third capacitor C3 is the positive input end of the LC resonance loop; the connection point of the second capacitor C2 and the fourth capacitor C4 is the negative input end of the LC resonance loop;

2. The split parallel resonant inverter of claim 1, wherein the ratio of the capacitances of the capacitor C12, the first capacitor C1, the capacitor C22, and the second capacitor C2 is C12: c1 =c22: c2 =1:5 to 1:10.

3. The split parallel resonant inverter of claim 1, wherein one end of the leakage reactance L3 is connected to an anode input end of the LC resonant circuit, the other end of the leakage reactance L3 is connected to a cathode input end of the LC resonant circuit, and a center tap of the leakage reactance L3 is connected to a node D of the LC resonant circuit; or one end of the leakage reactance L3 is connected with the positive electrode output end of the inverter bridge, the other end of the leakage reactance L3 is connected with the negative electrode output end of the inverter bridge, and the middle tap of the leakage reactance L3 is connected with the node O of the inverter bridge.

4. The split parallel resonant inverter of claim 1, wherein the split parallel resonant inverter comprises three connection modes, a first connection mode, a second connection mode, and a third connection mode;

5. The split parallel resonant inverter of claim 4, wherein the connection bolts are copper bolts or austenitic stainless steel bolts.

6. The split parallel resonant inverter according to claim 1, wherein the inductance network is formed by a seventh inductance L7 or by a fifth inductance L5, a seventh inductance L7, a sixth inductance L6 connected in series and then connected in parallel with a fourth inductance L4;

7. The split parallel resonant inverter of claim 6, wherein the fourth inductance L4 is a frequency regulated inductance, the seventh inductance L7 is an equivalent inductance of a load inductor, a transformer, or an electrode, the fifth inductance L5 and the sixth inductance L6 are current regulated inductances, and the inductance of the fifth inductance L5 and the sixth inductance L6 are equal.

8. The split parallel resonant inverter of claim 1, wherein the number of pairs of twisted pair and twisted pair cables, and the number of coaxial cables and shielded cables are determined according to actual requirements.