阅读说明：本技术 一种同步型感应加热电源主回路结构 (Synchronous induction heating power supply main loop structure ) 是由 李南坤 黄德华 于 2021-07-28 设计创作，主要内容包括：本发明提供了一种同步型感应加热电源主回路结构,其特征在于,直流电压供给电路的负端连接N个二极管一的阴极,N个二极管一的阳极分别与N个感应加热单元的直流分流器相连；N个感应加热单元中每两个感应加热单元的逆变桥的负极端之间连接有一组二极管组。本发明在每个单元的分流器后端串联二极管,利用二极管防止电流反向,确保通过分流器能够采集到准确的直流电流；本发明在每两个逆变桥的负端之间串联两个正反并联的二极管,防止两个逆变桥的直流电流相互分流,为感应电流提供环流回路,使得感应电流不会流过分流器,确保通过分流器能够采集到准确的直流电流。(The invention provides a main loop structure of a synchronous induction heating power supply, which is characterized in that the negative end of a direct-current voltage supply circuit is connected with the cathodes of N diodes I, and the anodes of the N diodes I are respectively connected with direct-current shunts of N induction heating units; and a group of diode groups are connected between the negative ends of the inverter bridges of every two induction heating units in the N induction heating units. According to the invention, the rear end of the shunt of each unit is connected with a diode in series, and the diode is used for preventing the current from reversing, so that the accurate direct current can be acquired through the shunt; according to the invention, two diodes which are connected in parallel in a positive and negative mode are connected in series between the negative terminals of each two inverter bridges, so that direct currents of the two inverter bridges are prevented from being mutually shunted, a circulating current loop is provided for induced current, the induced current cannot flow through the shunt, and accurate direct current can be acquired through the shunt.)

1. A synchronous induction heating power supply main loop structure comprises a direct current voltage supply circuit and N induction heating units, wherein N is more than or equal to 2, each induction heating unit comprises a direct current shunt, an inverter bridge, an isolation transformer and an induction coil, alternating current output by the inverter bridge flows through a primary winding of the isolation transformer, induced current output by a secondary winding of the isolation transformer flows through the induction coil, and the direct current shunt is connected to the negative end of the inverter bridge;

the positive terminals of the N inverter bridges are connected with the positive terminal of the direct-current voltage supply circuit;

the negative end of the direct-current voltage supply circuit is connected with the cathodes of the N first diodes, and the anodes of the N first diodes are respectively connected with the direct-current shunts of the N induction heating units;

and a group of diode groups are connected between the negative ends of the inverter bridges of every two induction heating units in the N induction heating units.

2. A synchronous induction heating power supply main loop structure as claimed in claim 1, wherein said diode is a high current fast diode.

3. A synchronous induction heating power supply main loop structure as claimed in claim 1, wherein a filter capacitor is connected across the positive terminal and the negative terminal of each said inverter bridge.

4. A synchronous type induction heating power supply main circuit structure as claimed in claim 1, wherein the dc voltage supply circuit includes an ac power supply interface connected to a circuit breaker connected to a three-phase rectifier bridge which outputs a dc voltage; the positive end of the direct-current voltage is connected to the positive ends of the N inverter bridges after passing through the buffer contactor and the smoothing reactor; and the two ends of the contactor are connected with a charging buffer circuit in parallel.

5. A synchronous type induction heating power supply main loop structure as claimed in claim 4, wherein said charging buffer circuit comprises a buffer resistor and a self-recovery fuse connected in series.

Technical Field

The invention relates to a main loop structure of a synchronous induction heating power supply.

Background

A common multi-unit output synchronous induction heating power supply adopts a common direct current bus mode, and circuits among a plurality of inverter units are not specially processed. When a plurality of induction coils are close to each other, magnetic fields in the induction coils are coupled with each other, and units with weaker magnetic fields in the induction coils are easily coupled to induction currents by units with stronger magnetic fields. The induced current is fed back to the direct current bus through an internal loop comprising an intermediate frequency transformer and an inverter bridge reverse rectification, and an induced circulation current is formed on the direct current bus. This induced circulating current will flow through the shunt of the induced cell. The power P is obtained by calculating the direct current voltage U and the direct current I collected by the current divider, and P is UxI. If the current signal on the current divider has an induced current and the current direction is opposite to the actual output current direction of the unit, a current cancellation effect is caused, the detected direct current I becomes smaller, the calculated power value P becomes smaller, and the power calculation is inaccurate. The system cannot acquire the actual output power of each unit, and power control cannot be performed.

As shown in fig. 1, taking a main loop structure of a synchronous induction heating power supply including two induction COILs and multiple unit outputs as an example, in a main loop of a conventional structure, magnetic field coupling between induction COILs COIL1 and COIL2 generates induced currents on a primary and an inverter loop of a transformer, the induced currents flow forward through a shunt RB2 and reverse through a shunt RB1, so that a collected direct current on the shunt RB2 is increased, and a collected direct current on the shunt RB1 is decreased, so that calculation power is inaccurate when calculating output power of each unit.

Disclosure of Invention

The purpose of the invention is: the power acquisition inaccuracy of each unit caused by mutual coupling of magnetic fields in the induction coils is prevented, and the power acquired by each unit is ensured to be the actual output power of the unit.

In order to achieve the above object, the technical solution of the present invention is to provide a main loop structure of a synchronous induction heating power supply, including a dc voltage supply circuit and N induction heating units, where N is greater than or equal to 2, each induction heating unit includes a dc shunt, an inverter bridge, an isolation transformer and an induction coil, an ac current output by the inverter bridge flows through a primary winding of the isolation transformer, an induced current output by a secondary winding of the isolation transformer flows through the induction coil, and the dc shunt is connected to a negative terminal of the inverter bridge, and the main loop structure of the synchronous induction heating power supply is characterized by further including N diodes i and N-1 diode groups composed of two diodes ii connected in parallel in reverse;

the positive terminals of the N inverter bridges are connected with the positive terminal of the direct-current voltage supply circuit;

the negative end of the direct-current voltage supply circuit is connected with the cathodes of the N first diodes, and the anodes of the N first diodes are respectively connected with the direct-current shunts of the N induction heating units;

and a group of diode groups are connected between the negative ends of the inverter bridges of every two induction heating units in the N induction heating units.

Preferably, the first diode is a high-current fast diode.

Preferably, a filter capacitor is connected between the positive terminal and the negative terminal of each inverter bridge in a bridging manner.

Preferably, the dc voltage supply circuit includes an ac power interface, the ac power interface is connected to a circuit breaker, the circuit breaker is connected to a three-phase rectifier bridge, and the three-phase rectifier bridge outputs dc voltage; the positive end of the direct-current voltage is connected to the positive ends of the N inverter bridges after passing through the buffer contactor and the smoothing reactor; and the two ends of the contactor are connected with a charging buffer circuit in parallel.

Preferably, the charging buffer circuit comprises a buffer resistor and a self-recovery fuse which are connected in series.

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

1) according to the invention, the rear end of the shunt of each unit is connected with a diode in series, and the diode is used for preventing the current from reversing, so that the accurate direct current can be acquired through the shunt;

2) according to the invention, two diodes which are connected in parallel in a positive and negative mode are connected in series between the negative terminals of each two inverter bridges, so that direct currents of the two inverter bridges are prevented from being mutually shunted, a circulating current loop is provided for induced current, the induced current cannot flow through a shunt, and accurate direct current can be acquired through the shunt;

drawings

FIG. 1 is a schematic diagram of a main circuit of a conventional synchronous induction heating power supply;

fig. 2 is a schematic structural diagram of a main loop of a synchronous induction heating power supply according to an embodiment;

fig. 3 is a schematic diagram illustrating the reverse flow of the induced current in fig. 2.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

The invention provides a main loop structure of a synchronous induction heating power supply, which is used for designing a main loop of the synchronous multi-output induction heating power supply and is applied to induction heating application occasions where a plurality of induction coils are close to each other and have magnetic field coupling. For example: the multi-unit zone heating heat treatment occasion, the crystal growth industry with double-coil heating, the bar on-line heating occasion with multi-temperature zone control requirement, and the like.

The present embodiment further describes the present invention by taking a main loop structure of a synchronous induction heating power supply including two induction COILs COIL1 and COIL2 as an example.

As shown in fig. 2, in order to achieve the main circuit structure of the synchronous induction heating power supply disclosed in this embodiment, a three-phase 380VAC power enters a circuit breaker KP1 through three-phase power supply interfaces L1, L2, and L3, is then connected to a three-phase rectifier bridge BD1, and is rectified by the three-phase rectifier bridge BD1 to output a dc voltage. The positive end of the direct current voltage passes through the buffer contactor K1 and the smoothing reactor L1 and then is connected to the positive ends of the inverter Bridge Bridge1 and the inverter Bridge Bridge 2. The buffer resistor R1 and the self-recovery fuse FR1 are connected in series and then connected in parallel at two ends of the contactor K1 to form a charging buffer circuit. The buffer circuit has the functions of eliminating current impact on the input circuit and the rectifier bridge when being powered on and reducing impact and interference on a power grid.

A capacitor C3 is connected across the positive terminal of the dc voltage and the negative terminal of the dc voltage. The negative terminal of the dc voltage is connected to the cathodes of the diodes D2 and D1. The anode of diode D1 is connected to the negative terminal of inverter Bridge1 via dc shunt RB 1. The anode of diode D2 is connected to the negative terminal of inverter Bridge2 via dc shunt RB 2. The induced current will be cut off by the diode D1 and the diode D2, so the induced current will not flow through the dc shunt RB1 and the dc shunt RB 2. The dc shunt RB1 and the dc shunt RB2 are used for detecting dc currents of the inverter Bridge1 and the inverter Bridge2, respectively.

And a filter capacitor C1 is connected between the positive terminal and the negative terminal of the inverter Bridge 1. The inverter Bridge1 is a full Bridge inverter Bridge composed of four IGBTs. Diode D1 uses a high current fast diode to prevent current reversal on dc shunt RB 1. The inverter Bridge1 inverts to output an alternating current, the alternating current passes through the primary winding of the intermediate frequency isolation transformer TRAN1 after passing through the blocking capacitor group CP1, the current induced by the secondary winding of the intermediate frequency isolation transformer TRAN1 passes through the resonant capacitor group CP3, and then passes through the induction COIL COIL1 to form a resonant circuit.

And a filter capacitor C2 is connected between the positive terminal and the negative terminal of the inverter Bridge 2. Bridge2 is a full Bridge inverter Bridge consisting of four IGBTs. Diode D2 uses a high current fast diode to prevent current reversal on dc shunt RB 2. The inverter Bridge2 inverts to output an alternating current, the alternating current flows through the primary winding of the intermediate frequency isolation transformer TRAN2 through the blocking capacitor bank CP2, the current is induced by the secondary winding of the intermediate frequency isolation transformer TRAN2 and then flows through the resonant capacitor bank CP4, and then the current passes through the induction COIL2 to form a resonant circuit.

Two diodes D3 connected in parallel in reverse are connected in series between the inversion Bridge1 and the negative terminal of the inversion Bridge2, so that the induced current directly passes through the diode D3 to form a circular current without passing through the direct current shunt RB1 and the direct current shunt RB 2. Another function of the diode D3 is that the power output dc current circuits for the inverter Bridge1 and the inverter Bridge2 do not affect each other. The direct current of the inverter Bridge1 flows through the direct current shunt RB1 and the diode D1 to return to the negative terminal of the three-phase rectifier Bridge BD1, and if the diode D3, the direct current shunt RB2 and the diode D2 return to the negative terminal of the three-phase rectifier Bridge BD1, the direct current needs to flow through two diodes, and because the voltage drop of the two diodes, namely the diode D3 and the diode D2, is twice that of the diode D1, the direct current of the inverter Bridge1 does not flow through the diode D3, the direct current shunt RB2 and the diode D2, and only flows through the direct current shunt RB1 and the diode D1. Similarly, the dc current of the inverter Bridge2 does not flow through the diode D3, the dc shunt RB1, the diode D1, but flows through the dc shunt RB2 and the diode D2.