Zinc melting induction furnace voltage transformation power supply based on IGBT series resonance

Abstract

The utility model relates to the technical field of equipment used together with a power supply or a similar power supply system, and discloses a zinc melting induction furnace variable-voltage power supply based on IGBT series resonance, which comprises two branch circuits which are respectively connected to a high-voltage input interface end in a triangular output connection mode and a star-shaped output connection mode, the two branch rear stages are respectively connected to the rectification circuit and then are connected to the IGBT half-bridge series resonance circuit in parallel, the output of the IGBT half-bridge series resonance circuit is respectively connected with a high-voltage output contact and a low-voltage output contact through a coil loop, the high voltage is 80-120V, and the low voltage is 12-24V. According to the utility model, the overall connection is simpler, the overall heat exchange efficiency is higher, the power supply stability is obviously better, the working reliability is higher, and power can be supplied to a plurality of multi-specification electric furnaces at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field of equipment used together with a power supply or a similar power supply system, in particular to the technical field of converting AC power input into DC power output. Background Art

[0002] Induction heating has the advantages of high efficiency, good working conditions, easy temperature control, small metal burnout, and no need for preheating. Fast thyristor (SCR) is still the main force of induction heating. It has high voltage resistance, large current, strong overcurrent and overvoltage resistance, but compared with mature IGBT power supplies, it has high failure rate, complex structure, and low power factor due to large grid-side harmonics when running at low power, which limits its scope of use. IGBT is a composite power device that combines the advantages of bipolar power transistors and power MOSFETs. It has the advantages of voltage-type control, large input impedance, small driving power, simple control circuit, small switching loss, and fast on-off speed.

[0003] When applying IGBT to the existing induction heating technology, the following problems still exist: the matching design for each zinc melting induction furnace has many redundant circuit connections, the overall heat exchange efficiency is low, and the power supply stability is poor. Utility Model Content

[0004] The utility model aims to provide a transformer power supply for a zinc melting induction furnace based on IGBT series resonance, which makes the overall circuit connection simple, the overall heat exchange efficiency high, and the power supply stability excellent.

[0005] In order to solve the above technical problems, the utility model provides a transformer power supply for a zinc melting induction furnace based on IGBT series resonance, including: two branch circuits connected to the high-voltage input interface end in two ways in a triangle output connection mode and a star output connection mode respectively, the two branches are respectively connected to the rectifier circuit at the rear stage, and then connected in parallel to the IGBT half-bridge series resonance circuit, the output of the IGBT half-bridge series resonance circuit is connected to two groups of high-voltage and low-voltage output contacts through a coil loop, the high voltage is 80~120V, and the low voltage is 12~24V.

[0006] The IGBT half-bridge series resonant circuit specifically comprises: two groups of parallel IGBT branches each having two parallel IGBT components.

[0007] The IGBT components all include parallel-connected IGBT monomers and buffer capacitors, and a resistor is connected in series on the branch where the buffer circuit is located.

[0008] The rectifier circuit is that each access point is connected in parallel with two diodes, the diodes are independently connected in parallel with capacitors, and the branches where the two diodes are located are connected to two input contacts of the IGBT half-bridge series resonant circuit.

[0009] The capacitors connected in parallel with the diodes are connected in series with resistors.

[0010] The output circuit of the IGBT half-bridge series resonant circuit is connected in series with an inductor coil, which is connected to a transformer coil and forms a loop with the transformer coil. The transformer coil matches two sets of high-voltage and low-voltage output coils, and the two sets of output coils are connected to two sets of output contacts.

[0011] The transformer coil is an iron core coil.

[0012] The IGBT half-bridge series resonant circuit is connected in parallel with a buffer capacitor group.

[0013] The buffer capacitor group is a two-way parallel capacitor assembly, and each group of capacitor assemblies has more than three capacitors connected in full parallel.

[0014] A voltmeter is connected in parallel to the IGBT half-bridge series resonant circuit, and an ammeter is connected in series to one of the input circuits connected in parallel to the IGBT half-bridge series resonant circuit.

[0015] Compared with the prior art, the utility model has a simpler overall connection, higher overall heat exchange efficiency, significantly better power supply stability, stronger working reliability, and can supply power to multiple electric furnaces of various specifications at the same time.

[0016] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0018] Figure 1 It is a connection diagram according to at least one embodiment of the utility model. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the utility model clearer, each embodiment of the utility model will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in each embodiment of the utility model, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the utility model. The various embodiments can be combined with each other and referenced to each other without contradiction.

[0020] The first embodiment of the utility model relates to a transformer power supply for a zinc melting induction furnace based on IGBT series resonance, comprising: two branch circuits connected to a high-voltage input interface end in two ways in a triangle output connection mode and a star output connection mode respectively, the two branches are respectively connected to a rectifier circuit at the rear stage, and then connected in parallel to an IGBT half-bridge series resonance circuit, the output of the IGBT half-bridge series resonance circuit is connected to two groups of high-voltage and low-voltage output contacts through a coil loop, the high voltage is 80-120V, and the low voltage is 12-24V.

[0021] The IGBT element can be turned on or off by the gate voltage. In any case, as long as there is no voltage on its gate, the IGBT element is turned off. Therefore, the operating frequency of the IGBT half-bridge series resonant power supply can be changed arbitrarily. According to the working principle of the series resonant circuit, when the operating frequency changes, the phase angle of the furnace voltage and current changes accordingly, which also changes the power sent to the furnace. Therefore, the IGBT half-bridge series inverter can adjust the output power by adjusting the operating frequency. It can be powered by a fixed voltage source and uses uncontrolled rectification. Its grid-side power factor is close to 1 and has nothing to do with the output power.

[0022] This embodiment is based on the connection mode of two-way rectification and merging into one IGBT half-bridge series resonant circuit. It not only effectively utilizes the advantages of the IGBT half-bridge series resonant circuit on the grid side, which has a power factor close to 1 and almost no harmonic interference, but also makes the overall connection more concise and reliable. At the same time, it is based on the parallel access mode of the triangle output connection mode and the star output connection mode, which effectively combines the advantages of the star connection method and the triangle connection method. It can be applied to both high-power output and low-power output, which greatly ensures the stable operation of the zinc melting induction furnace. The IGBT half-bridge series resonant power supply adjusts the output power by adjusting the operating frequency of the inverter. The DC voltage output by the rectifier circuit is fixed. Therefore, based on the rectifier circuit, it can work with multiple inverters at the same time. In the above-mentioned two-way power supply situation, the rectifier circuit supplies power to two inverters at the same time, so that two electric furnaces can work at the same time.

[0023] The second embodiment of the present invention is substantially the same as the first embodiment, mainly in that it is a further preferred solution of the IGBT half-bridge series resonant circuit. The IGBT half-bridge series resonant circuit specifically includes: two groups of parallel IGBT branches each have two parallel IGBT components.

[0024] Furthermore, each IGBT assembly includes an IGBT monomer and a buffer capacitor connected in parallel, and a resistor is connected in series on the branch where the buffer circuit is located.

[0025] Further, a voltmeter is connected in parallel to the IGBT half-bridge series resonant circuit. Further, an ammeter is connected in series to one of the input circuits of the IGBT half-bridge series resonant circuit.

[0026] Furthermore, a buffer capacitor group is connected in parallel to the IGBT half-bridge series resonant circuit.

[0027] Furthermore, the buffer capacitor group is two parallel capacitor components, and each group of capacitor components has more than three capacitors connected in full parallel.

[0028] Therefore, based on the improvement of the connection method of capacitors and IGBT components in the conventional IGBT half-bridge series resonant circuit, the commutation efficiency as a current source power supply can be effectively improved, the power supply stability can be greatly improved, and the power factor on the grid side can be further effectively improved.

[0029] The third implementation mode of the utility model is substantially the same as the first implementation mode, mainly in that other specific means are further optimized. Furthermore, the rectifier circuit is that each access point is connected in parallel with two diodes, the diodes are independently connected in parallel with capacitors, and the branches where the two diodes are located are connected to the two input contacts of the IGBT half-bridge series resonant circuit.

[0030] Furthermore, the capacitor connected in parallel with the diode independently has a resistor connected in series.

[0031] Furthermore, the output circuit of the IGBT half-bridge series resonant circuit is connected in series with an inductor coil, which is connected to the transformer coil and forms a loop with the transformer coil. The transformer coil matches two sets of high-voltage and low-voltage output coils, and the two sets of output coils are connected to two sets of output contacts.

[0032] Furthermore, the transformer coil is an iron core coil.

[0033] Therefore, the utility model is powered by a voltage source as an IGBT half-bridge series resonant power supply. In order to avoid the inverter upper and lower bridge arm switches being turned on at the same time during the commutation process, causing the voltage source to short-circuit, it must be ensured that it is turned off first and then turned on in the control, that is, the existence of dead time must be ensured. The inverter of the thyristor parallel resonant power supply is powered by a current source. In order to avoid a large induced potential on the DC filter inductor Ld during commutation, the current must be continuous, that is, the principle of turning on first and then turning off must be followed during commutation to ensure the existence of overlap time. During the overlap time, although the inverter bridge kidney is directly connected, since Ld is relatively large, the current rise rate can be limited and the DC power supply will not be short-circuited, but too long commutation will reduce the system efficiency, so the overlap time should not be too long.

[0034] On the other hand, the above technical solution is relatively simple to start, while the common thyristor parallel power supply in the prior art is relatively difficult to start. Before starting, the DC filter large inductor needs to be pre-charged to ensure that it is current, and can only work in a self-excited state. When the drive signal frequency is not equal to the inherent resonant frequency of the load, the system cannot start. Therefore, the inherent resonant frequency of the load must be measured before the parallel resonant power supply is started.

[0035] On the other hand, when the resonant frequency of the load changes continuously with the heating process, even if the control circuit fails to track the frequency change, the utility model will only cause the load power factor to change, and will not cause failures such as oscillation stop or inverter subversion. During the induction heating process of the thyristor parallel resonant power supply, the equivalent impedance and other parameters of the load will change to a certain extent, so the resonant frequency of the load will change accordingly. At this time, if the inverter control circuit cannot track the load resonant frequency in a timely and accurate manner, the inverter may stop oscillating, or even cause an inverter subversion failure. Therefore, compared with traditional power supply solutions, the working reliability is stronger.

[0036] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A transformer power supply for zinc melting induction furnace based on IGBT series resonance, characterized in that: include: The two branches are connected to the high-voltage input interface end in two ways in a triangle output connection mode and a star output connection mode respectively. The two branches are connected to the rectifier circuit respectively and then connected to the IGBT half-bridge series resonant circuit in parallel. The output of the IGBT half-bridge series resonant circuit is connected to two groups of high-voltage and low-voltage output contacts through a coil loop. The high voltage is 80-120V and the low voltage is 12-24V.

2. The zinc melting induction furnace transformer power supply based on IGBT series resonance according to claim 1 is characterized in that: The IGBT half-bridge series resonant circuit specifically comprises: two groups of parallel IGBT branches each having two parallel IGBT components.

3. The zinc melting induction furnace transformer power supply based on IGBT series resonance according to claim 2 is characterized in that: The IGBT components all include parallel-connected IGBT monomers and buffer capacitors, and a resistor is connected in series on the branch where the buffer circuit is located.

4. The zinc melting induction furnace transformer power supply based on IGBT series resonance according to claim 1 is characterized in that: The rectifier circuit is that each access point is connected in parallel with two diodes, the diodes are independently connected in parallel with capacitors, and the branches where the two diodes are located are connected to two input contacts of the IGBT half-bridge series resonant circuit.

5. The zinc melting induction furnace transformer power supply based on IGBT series resonance according to claim 4 is characterized in that: The capacitors connected in parallel with the diodes are connected in series with resistors.

6. The zinc melting induction furnace transformer power supply based on IGBT series resonance according to claim 1 is characterized in that: The output circuit of the IGBT half-bridge series resonant circuit is connected in series with an inductor coil, which is connected to a transformer coil and forms a loop with the transformer coil. The transformer coil matches two sets of high-voltage and low-voltage output coils, and the two sets of output coils are connected to two sets of output contacts.

7. The zinc melting induction furnace transformer power supply based on IGBT series resonance according to claim 6 is characterized in that: The transformer coil is an iron core coil.

8. The zinc melting induction furnace transformer power supply based on IGBT series resonance according to claim 1 is characterized in that: The IGBT half-bridge series resonant circuit is connected in parallel with a buffer capacitor group.

9. The zinc melting induction furnace transformer power supply based on IGBT series resonance according to claim 8 is characterized in that: The buffer capacitor group is a two-way parallel capacitor assembly, and each group of capacitor assemblies has more than three capacitors connected in full parallel.

10. The zinc melting induction furnace transformer power supply based on IGBT series resonance according to claim 1 is characterized in that: A voltmeter is connected in parallel to the IGBT half-bridge series resonant circuit, and an ammeter is connected in series to one of the input circuits connected in parallel to the IGBT half-bridge series resonant circuit.

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