Double-frequency switching IGBT (Insulated Gate Bipolar Translator) power supply

Abstract

The invention provides a double-frequency switching IGBT (Insulated Gate Bipolar Translator) power supply, which comprises a three-phase power supply module, the input end of the rectifying circuit module is connected with the output end of the three-phase power supply module; the positive input end and the negative input end of the inverter circuit module are respectively connected with the positive output end and the negative output end of the rectifier circuit module; two input ends of the resonance circuit module are respectively connected with two output ends of the inverter circuit module; the resonant circuit module comprises a first frequency switching unit, a second frequency switching unit, an induction coil unit and a resonant capacitor unit; the first frequency switching unit is closed, the second frequency switching unit is disconnected, the capacitance of the resonant capacitor unit is a first capacitance, and the induction coil unit vibrates according to a first resonant frequency; the first frequency switching unit is switched off, the second frequency switching unit is switched on, the capacitance of the resonant capacitor unit is a second capacitance, and the induction coil unit vibrates according to a second resonant frequency; the second resonant frequency is smaller than the first resonant frequency, and the second capacitance is larger than the first capacitance.

Description

Technical Field

[0001] The invention relates to the technical field of IGBT power supplies, and in particular to a dual-frequency switching IGBT power supply. Background Art

[0002] With the development of modern metallurgical industry, vacuum induction melting furnaces have been widely used in the research and production of nickel-based and special steels, precision alloys, active metals, high-temperature alloys and magnetic materials.

[0003] Existing vacuum induction melting furnaces generally adopt the working mode of melting in the atmosphere and then degassing in a vacuum. The power supply is used as induction heating to heat and melt the metal materials in the vacuum furnace into molten metal in the atmosphere. Then, a three-phase power frequency transformer is used to electromagnetically stir the molten metal in a vacuum environment. With the help of electromagnetic force, the molten metal rolls and flows, and impurity gases are precipitated, thereby achieving the purpose of purifying the molten metal. The three-phase power frequency transformer is an electromagnetic stirrer with a mature solution and simple principle. As long as it is connected to the induction coil of the vacuum furnace, an industrial frequency magnetic field can be established in the induction coil after power is turned on, thereby achieving the stirring effect of the molten metal.

[0004] However, the disadvantage of the above solution is that the equipment occupies a large area, and a transformer room needs to be built near the vacuum furnace to place the transformer and its switch cabinet. Secondly, there is a certain distance between the transformer and the vacuum furnace, which requires a long power supply line between the two, and the power loss on the power supply line is large. Therefore, the overall construction cost and operation cost of the equipment are high and cannot meet actual needs. Summary of the invention

[0005] The present invention provides a dual-frequency switching IGBT power supply, which is used to solve the technical problem in the prior art that the IGBT power supply cannot be switched arbitrarily between high frequency and low frequency.

[0006] In one aspect, the present invention provides a dual-frequency switching IGBT power supply, comprising: A three-phase power module having an output terminal; A rectifier circuit module, having an input end, a positive output end and a negative output end, and the input end of the rectifier circuit module is connected to the output end of the three-phase power supply module; An inverter circuit module has a positive input terminal, a negative input terminal and two output terminals, and the positive input terminal and the negative input terminal of the inverter circuit module are respectively connected to the positive output terminal and the negative output terminal of the rectifier circuit module; A resonant circuit module having two input ends, wherein the two input ends of the resonant circuit module are respectively connected to the two output ends of the inverter circuit module; Wherein, the resonant circuit module includes a first frequency switching unit, a second frequency switching unit, an induction coil unit and a resonant capacitor unit; When the first frequency switching unit is closed and the second frequency switching unit is open, the capacitance of the resonant capacitor unit is the first capacitance, and the induction coil unit vibrates at the first resonant frequency to meet the melting working state of the vacuum induction melting furnace; When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the capacitance of the resonant capacitor unit is the second capacitance, and the induction coil unit vibrates at a second resonant frequency to meet the stirring working state of the vacuum induction melting furnace; wherein the second resonant frequency is less than the first resonant frequency, and the second capacitance is greater than the first capacitance.

[0007] According to a dual-frequency switching IGBT power supply provided by the present invention, the induction coil unit includes an induction coil L1 and an induction coil L2; When the first frequency switching unit is closed and the second frequency switching unit is opened, the induction coil L1 and the induction coil L2 are in parallel state; When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the induction coil L1 and the induction coil L2 are in a series connection state.

[0008] According to a dual-frequency switching IGBT power supply provided by the present invention, the resonant capacitor unit includes a resonant capacitor C2 and a resonant capacitor C3; When the first frequency switching unit is closed and the second frequency switching unit is opened, one of the resonant capacitor C2 and the resonant capacitor C3 is connected in parallel with the induction coil unit, and the other is in a disconnected state; When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the resonant capacitor C2, the resonant capacitor C3 and the induction coil unit are connected in parallel.

[0009] According to a dual-frequency switching IGBT power supply provided by the present invention, the first frequency switching unit includes a switch K2 and a switch K3, and the second frequency switching unit includes a switch K1 and a switch K4; The two ends of the resonant capacitor C2 are respectively connected to the two output ends of the inverter circuit module; The resonant capacitor C3 is connected in series with the switch K1 and then connected in parallel to both ends of the resonant capacitor C2; The induction coil L1, the switch K4 and the induction coil L2 are connected in sequence and then connected in parallel to the two ends of the resonant capacitor C2; One end of the switch K2 is connected between the induction coil L1 and the switch K4, and the other end is connected to one end of the resonant capacitor C2; One end of the switch K3 is connected between the induction coil L2 and the switch K4 , and the other end is connected to the other end of the resonant capacitor C2 .

[0010] According to a dual-frequency switching IGBT power supply provided by the present invention, the inverter circuit module includes a reactor Ld1, a filter capacitor C1, an IGBT module VT1, an IGBT module VT2, an IGBT module VT3, an IGBT module VT4, and a reactor Ld2; The positive input end of the reactor Ld1 is connected to the positive input end of the inverter circuit module, and the negative input end of the reactor Ld1 is connected to the negative input end of the inverter circuit module; The two ends of the filter capacitor C1 are connected in parallel to the two output ends of the reactor Ld1; The collector of the IGBT module VT1 is connected to the positive output terminal of the reactor Ld1, and the emitter of the IGBT module VT1 is connected to the collector of the IGBT module VT2; The emitter of the IGBT module VT2 is connected to the negative output terminal of the reactor Ld1; The collector of the IGBT module VT3 is connected to the positive output terminal of the reactor Ld1, and the emitter of the IGBT module VT3 is connected to the collector of the IGBT module VT4; The emitter of the IGBT module VT4 is connected to the negative output terminal of the reactor Ld1; The intersection of the IGBT module VT1 and the IGBT module VT2 is connected to an input end of the reactor Ld2; The intersection of the IGBT module VT3 and the IGBT module VT4 is connected to the other input end of the reactor Ld2; The two output ends of the reactor Ld2 serve as the two output ends of the inverter circuit module.

[0011] According to a dual-frequency switching IGBT power supply provided by the present invention, the resonant capacitor C2, the resonant capacitor C3 and the inverter circuit module are arranged in the same cabinet.

[0012] According to a dual-frequency switching IGBT power supply provided by the present invention, the switch K1, the switch K2, the switch K3, the switch K4, the resonant capacitor C2 and the resonant capacitor C3 are arranged in the same cabinet.

[0013] According to a dual-frequency switching IGBT power supply provided by the present invention, the rectifier circuit module includes a rectifier diode D.

[0014] According to a dual-frequency switching IGBT power supply provided by the present invention, the second resonant frequency is 25% to 45% of the first resonant frequency.

[0015] According to a dual-frequency switching IGBT power supply provided by the present invention, the second resonant frequency is 30% of the first resonant frequency.

[0016] The present invention provides a dual-frequency switching IGBT power supply, which may include a three-phase power supply module, a rectifier circuit module, an inverter circuit module and a resonant circuit module. The resonant circuit module includes a first frequency switching unit, a second frequency switching unit, an induction coil unit and a resonant capacitor unit. When the first frequency switching unit is closed and the second frequency switching unit is disconnected, the capacitance of the resonant capacitor unit is the first capacitance, and the induction coil unit vibrates according to the first resonant frequency. When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the capacitance of the resonant capacitor unit is the second capacitance, and the induction coil unit vibrates according to the second resonant frequency. The dual-frequency switching IGBT power supply is switched between two different resonant frequencies. The smelting working state and stirring working state of the vacuum induction melting furnace are met without the need to use a three-phase industrial frequency transformer, thereby reducing the cost of equipment and power supply lines, thereby reducing the power loss of the power supply lines, and reducing the land cost. This dual-frequency working mode also improves the adaptability and flexibility of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a structural schematic diagram of a dual-frequency switching IGBT power supply provided by an embodiment of the present invention; Figure 2 is a schematic diagram of an equivalent structure in which the first frequency switching unit provided by an embodiment of the present invention is closed and the second frequency switching unit is disconnected; Figure 3 It is a schematic diagram of an equivalent structure in which the first frequency switching unit provided in an embodiment of the present invention is disconnected and the second frequency switching unit is closed. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Figure 1 It is a structural schematic diagram of a dual-frequency switching IGBT power supply provided by an embodiment of the present invention; Figure 2 is a schematic diagram of an equivalent structure in which the first frequency switching unit provided by an embodiment of the present invention is closed and the second frequency switching unit is disconnected; Figure 3 It is a schematic diagram of an equivalent structure in which the first frequency switching unit provided in an embodiment of the present invention is disconnected and the second frequency switching unit is closed.

[0021] See also Figures 1 to 3 A dual-frequency switching IGBT power supply may include a three-phase power supply module 101 , a rectifier circuit module 102 , an inverter circuit module 103 and a resonant circuit module 104 .

[0022] The three-phase power supply module 101 has an output terminal and includes a first phase line L1, a second phase line L2, and a third phase line L3.

[0023] The rectifier circuit module 102 has an input terminal, a positive output terminal and a negative output terminal, and the input terminal of the rectifier circuit module 102 is connected to the output terminal of the three-phase power supply module 101 .

[0024] The inverter circuit module 103 has a positive input terminal, a negative input terminal and two output terminals, and the positive input terminal and the negative input terminal of the inverter circuit module 103 are connected to the positive output terminal and the negative output terminal of the rectifier circuit module 102 respectively.

[0025] The resonant circuit module 104 has two input terminals, and the two input terminals of the resonant circuit module 104 are respectively connected to the two output terminals of the inverter circuit module 103 .

[0026] The resonant circuit module 104 includes a first frequency switching unit, a second frequency switching unit, an induction coil unit and a resonant capacitor unit.

[0027] When the first frequency switching unit is closed and the second frequency switching unit is open, the capacitance of the resonant capacitor unit is the first capacitance, and the induction coil unit vibrates at the first resonant frequency to meet the smelting working state of the vacuum induction melting furnace. At this time, the DC voltage output by the rectifier circuit module 102 and the resonant frequency of the resonant circuit module 104 are 100% of the rated state.

[0028] When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the capacitance of the resonant capacitor unit is the second capacitance, and the induction coil unit vibrates at the second resonant frequency to meet the stirring working state of the vacuum induction melting furnace; wherein the second resonant frequency is less than the first resonant frequency, and the second capacitance is greater than the first capacitance. The DC voltage output by the rectifier circuit module 102 and the resonant frequency of the resonant circuit module 104 can be 30% of the rated state.

[0029] In this embodiment, the dual-frequency switching IGBT power supply may include a three-phase power supply module 101, a rectifier circuit module 102, an inverter circuit module 103 and a resonant circuit module 104. The resonant circuit module 104 includes a first frequency switching unit, a second frequency switching unit, an induction coil unit and a resonant capacitor unit. When the first frequency switching unit is closed and the second frequency switching unit is disconnected, the capacitance of the resonant capacitor unit is the first capacitance, and the induction coil unit vibrates at the first resonant frequency. When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the capacitance of the resonant capacitor unit is the second capacitance, and the induction coil unit vibrates at the second resonant frequency. The dual-frequency switching IGBT power supply is switched between two different resonant frequencies. The smelting working state and the stirring working state of the vacuum induction melting furnace are met without the need to use a three-phase industrial frequency transformer, thereby reducing the cost of equipment and power supply lines, thereby reducing the power loss of the power supply lines, and reducing the land cost. This dual-frequency working mode also improves the adaptability and flexibility of the power supply.

[0030] In one embodiment of the present specification, the induction coil unit includes an induction coil L1 and an induction coil L2; When the first frequency switching unit is closed and the second frequency switching unit is opened, the induction coil L1 and the induction coil L2 are in parallel state; When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the induction coil L1 and the induction coil L2 are in a series connection state.

[0031] In this embodiment, precise control of the electromagnetic stirring force is achieved by switching the induction coil L1 and the induction coil L2 in parallel and in series at different frequencies. When the induction coil L1 and the induction coil L2 are in parallel, the electromagnetic force generated is strong and suitable for the melting state; when the induction coil L1 and the induction coil L2 are in series, the electromagnetic force is weak and suitable for the stirring state. This design improves the adaptability and flexibility of the power supply, while optimizing the efficiency of the melting and stirring processes. The two ends of the induction coil L1 can be regarded as the A end and the B end. The two ends of the induction coil L2 can be regarded as the C end and the D end.

[0032] In one embodiment of the present specification, the resonant capacitor unit includes a resonant capacitor C2 and a resonant capacitor C3; When the first frequency switching unit is closed and the second frequency switching unit is disconnected, one of the resonant capacitor C2 and the resonant capacitor C3 is connected in parallel with the induction coil unit, and the other is in a disconnected state; When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the resonant capacitor C2 and the resonant capacitor C3 are connected in parallel with the induction coil unit.

[0033] In this embodiment, the dynamic configuration of the resonant capacitor C2 and the resonant capacitor C3 allows the dual-frequency switching IGBT power supply to adjust the resonant frequency in different working states to adapt to different working requirements. In the high-frequency working state, one of the resonant capacitor C2 and the resonant capacitor C3 is connected in parallel with the induction coil unit, and the other is in a disconnected state to maintain a higher resonant frequency. In the low-frequency working state, the resonant capacitor C2 and the resonant capacitor C3 are connected in parallel with the induction coil unit to reduce the resonant frequency. The above design improves the regulation capability and working efficiency of the dual-frequency switching IGBT power supply.

[0034] In one embodiment of the present specification, the first frequency switching unit includes a switch K2 and a switch K3, and the second frequency switching unit includes a switch K1 and a switch K4; The two ends of the resonant capacitor C2 are respectively connected to the two output ends of the inverter circuit module 103; After the resonant capacitor C3 is connected in series with the switch K1, it is connected in parallel to both ends of the resonant capacitor C2; The induction coil L1, the switch K4 and the induction coil L2 are connected in sequence and then connected in parallel to the two ends of the resonant capacitor C2; One end of the switch K2 is connected between the induction coil L1 and the switch K4, and the other end is connected to one end of the resonant capacitor C2; One end of the switch K3 is connected between the induction coil L2 and the switch K4 , and the other end of the switch K3 is connected to the other end of the resonant capacitor C2 .

[0035] In this embodiment, precise control of the resonant capacitor and the induction coil is achieved through a specific switch configuration and connection method. This configuration not only improves the flexibility and adaptability of the power supply, but also helps to achieve the best electromagnetic stirring effect under different working conditions, while reducing energy loss and improving the overall efficiency of the system. Switch K2, switch K3, switch K1 and switch K4 can be driven manually, electrically, pneumatically, etc.

[0036] It can be understood that when the capacitance increases, the resonant frequency applied to the coil will decrease. If the frequency decreases, the time of the alternating electromagnetic field in the coil becomes longer, which increases the size of the eddy current, thereby causing an increase in the electromagnetic stirring force. Therefore, it is necessary to put the resonant capacitor C3 into the circuit through the switch K1, so as to reduce the resonant frequency of the induction coil L1 and the induction coil L2, so that its electromagnetic stirring effect is close to that of a three-phase power frequency transformer.

[0037] When the resonant frequency decreases, the DC voltage transmitted to the inverter circuit module 103 must be decreased to keep the inductance of the reactor Ld2 constant, thereby making the size of the reactor Ld2 as small as possible, saving the manufacturing cost and installation space of the reactor, and keeping the size of the dual-frequency switching IGBT power supply within a reasonable range. Therefore, when the switch K1 is closed, the DC voltage output by the rectifier circuit module 102 needs to decrease proportionally with the resonant frequency.

[0038] In one embodiment of the present specification, the inverter circuit module 103 includes a reactor Ld1, a filter capacitor C1, an IGBT module VT1, an IGBT module VT2, an IGBT module VT3, an IGBT module VT4, and a reactor Ld2; The positive input terminal of the reactor Ld1 is connected to the positive input terminal of the inverter circuit module 103, and the negative input terminal of the reactor Ld1 is connected to the negative input terminal of the inverter circuit module 103; The two ends of the filter capacitor C1 are connected in parallel to the two output ends of the reactor Ld1; The collector of IGBT module VT1 is connected to the positive output terminal of reactor Ld1, and the emitter of IGBT module VT1 is connected to the collector of IGBT module VT2; The emitter of the IGBT module VT2 is connected to the negative output terminal of the reactor Ld1; The collector of IGBT module VT3 is connected to the positive output terminal of reactor Ld1, and the emitter of IGBT module VT3 is connected to the collector of IGBT module VT4; The emitter of the IGBT module VT4 is connected to the negative output terminal of the reactor Ld1; The intersection of IGBT module VT1 and IGBT module VT2 is connected to an input terminal of reactor Ld2; The intersection of IGBT module VT3 and IGBT module VT4 is connected to the other input terminal of reactor Ld2; The two output ends of the reactor Ld2 serve as the two output ends of the inverter circuit module 103 .

[0039] In this embodiment, IGBT module VT1, IGBT module VT2, IGBT module VT3 and IGBT module VT4 are IGBT modules with damping diodes. Reactor Ld1 is a DC reactor. Reactor Ld2 is an AC reactor. The combination of reactor Ld1 and filter capacitor C1 helps to reduce voltage and current fluctuations, while the use of IGBT modules improves the switching speed and efficiency of the power supply and reduces switching losses.

[0040] The working process of the dual-frequency switching IGBT power supply is as follows: the three-phase power supply module 101 provides three-phase alternating current, which is rectified by the rectifying circuit module 102 to provide a direct current power supply for the inverter circuit module 103. Through the combination of closing and opening of the switch K1, the switch K2, the switch K3 and the switch K4, the induction coil L1 and the induction coil L2 in the induction coil unit are switched between high frequency and low frequency.

[0041] In one embodiment of the present specification, the resonant capacitor C2, the resonant capacitor C3 and the inverter circuit module 103 are arranged in the same cabinet.

[0042] In this embodiment, the resonant capacitor C2 and the resonant capacitor C3 are arranged in the same cabinet with the inverter circuit module 103, which helps to reduce space occupation and improve the integration and compactness of the system. This layout simplifies the installation and maintenance of the system, and also reduces the complexity and cost of the system.

[0043] In one embodiment of the present specification, the switch K1 , the switch K2 , the switch K3 , the switch K4 , the resonant capacitor C2 and the resonant capacitor C3 are arranged in the same cabinet.

[0044] In this embodiment, the switches K1, K2, K3, K4, and the resonant capacitors C2 and C3 are arranged in the same cabinet, which further improves the integration and compactness of the system. This design helps to reduce the use of connecting wires, reduce signal interference and energy loss, and improve the stability and reliability of the system.

[0045] It can be understood that when the resonant capacitor C2 and the resonant capacitor C3 are arranged in the same cabinet as the inverter circuit module 103, the resonant capacitor C2 and the resonant capacitor C3 are no longer arranged in the same cabinet as the switches. When the switch K1, the switch K2, the switch K3, the switch K4, the resonant capacitor C2 and the resonant capacitor C3 are arranged in the same cabinet, the resonant capacitor C2 and the resonant capacitor C3 are no longer arranged in the same cabinet as the inverter circuit module 103.

[0046] In one embodiment of the present specification, the rectifying circuit module 102 includes a rectifying diode D.

[0047] In this embodiment, the use of the rectifier diode D helps to convert the AC power provided by the three-phase power supply module 101 into DC power, thereby providing a stable DC power supply for the subsequent inverter circuit module 103 .

[0048] In one embodiment of the present specification, the second resonant frequency is 25% to 45% of the first resonant frequency.

[0049] In this embodiment, the second resonant frequency is 25% to 45% of the first resonant frequency. This design allows the dual-frequency switching IGBT power supply to provide sufficient electromagnetic stirring force in a low-frequency state, while achieving efficient melting in a high-frequency state. This wide range of frequency adjustment capability improves the adaptability and flexibility of the dual-frequency switching IGBT power supply, enabling the dual-frequency switching IGBT power supply to adapt to different working conditions and requirements.

[0050] In one embodiment of the present specification, the second resonant frequency is 30% of the first resonant frequency.

[0051] In this embodiment, the second resonant frequency is 30% of the first resonant frequency. This specific frequency ratio provides the best stirring effect while maintaining the efficiency and stability of the system. This design helps to achieve a more uniform flow of molten metal during the stirring process and improves the smelting quality.

[0052] The DC voltage in the stirring state can also be 30% of the DC voltage in the smelting state. That is to say, when the coil resonance frequency of the resonant circuit module 104 is reduced, the DC voltage output by the rectifier circuit module 102 needs to be reduced in proportion to the resonance frequency (the proportion can be any value between 1-100%), so that the size of the reactor Ld2 can be kept to a minimum, saving costs and space.

[0053] In summary, compared with the existing IGBT power supply, the present invention configures additional resonant capacitors and switches in the IGBT power supply, so that the IGBT power supply can switch between high frequency and low frequency at will. When the dual-frequency switching IGBT power supply switches the resonant circuit to operate in a low-frequency state, the electromagnetic stirring effect it produces can completely replace the power frequency transformer, so that the vacuum induction melting furnace can meet the two working conditions of melting and stirring by one IGBT power supply without a matching power frequency transformer. As a result, the power frequency transformer, switch cabinet and its power supply line can be eliminated, thereby reducing the corresponding equipment construction and use and maintenance costs. In addition, the resonant capacitor, switch and inverter circuit module 103 in the dual-frequency switching IGBT power supply can be centrally arranged in the same cabinet to reduce the equipment footprint. Furthermore, if the equipment space is further compressed, it can also be arranged separately, flexibly arranged, and the remaining space can be used to the maximum extent.

[0054] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0055] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-frequency switching IGBT power supply, characterized in that: include: A three-phase power module having an output terminal; A rectifier circuit module, having an input end, a positive output end and a negative output end, and the input end of the rectifier circuit module is connected to the output end of the three-phase power supply module; An inverter circuit module has a positive input terminal, a negative input terminal and two output terminals, and the positive input terminal and the negative input terminal of the inverter circuit module are respectively connected to the positive output terminal and the negative output terminal of the rectifier circuit module; A resonant circuit module having two input ends, wherein the two input ends of the resonant circuit module are respectively connected to the two output ends of the inverter circuit module; Wherein, the resonant circuit module includes a first frequency switching unit, a second frequency switching unit, an induction coil unit and a resonant capacitor unit; When the first frequency switching unit is closed and the second frequency switching unit is open, the capacitance of the resonant capacitor unit is the first capacitance, and the induction coil unit vibrates at the first resonant frequency to meet the melting working state of the vacuum induction melting furnace; When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the capacitance of the resonant capacitor unit is the second capacitance, and the induction coil unit vibrates at a second resonant frequency to meet the stirring working state of the vacuum induction melting furnace; wherein the second resonant frequency is less than the first resonant frequency, and the second capacitance is greater than the first capacitance.

2. The dual-frequency switching IGBT power supply according to claim 1, characterized in that: The induction coil unit includes an induction coil L1 and an induction coil L2; When the first frequency switching unit is closed and the second frequency switching unit is opened, the induction coil L1 and the induction coil L2 are in parallel state; When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the induction coil L1 and the induction coil L2 are in a series connection state.

3. The dual-frequency switching IGBT power supply according to claim 2, characterized in that: The resonant capacitor unit includes a resonant capacitor C2 and a resonant capacitor C3; When the first frequency switching unit is closed and the second frequency switching unit is opened, one of the resonant capacitor C2 and the resonant capacitor C3 is connected in parallel with the induction coil unit, and the other is in a disconnected state; When the first frequency switching unit is disconnected and the second frequency switching unit is closed, the resonant capacitor C2, the resonant capacitor C3 and the induction coil unit are connected in parallel.

4. The dual-frequency switching IGBT power supply according to claim 3, characterized in that: The first frequency switching unit includes a switch K2 and a switch K3, and the second frequency switching unit includes a switch K1 and a switch K4; The two ends of the resonant capacitor C2 are respectively connected to the two output ends of the inverter circuit module; The resonant capacitor C3 is connected in series with the switch K1 and then connected in parallel to both ends of the resonant capacitor C2; The induction coil L1, the switch K4 and the induction coil L2 are connected in sequence and then connected in parallel to the two ends of the resonant capacitor C2; One end of the switch K2 is connected between the induction coil L1 and the switch K4, and the other end is connected to one end of the resonant capacitor C2; One end of the switch K3 is connected between the induction coil L2 and the switch K4 , and the other end is connected to the other end of the resonant capacitor C2 .

5. The dual-frequency switching IGBT power supply according to claim 1, characterized in that: The inverter circuit module includes a reactor Ld1, a filter capacitor C1, an IGBT module VT1, an IGBT module VT2, an IGBT module VT3, an IGBT module VT4, and a reactor Ld2; The positive input end of the reactor Ld1 is connected to the positive input end of the inverter circuit module, and the negative input end of the reactor Ld1 is connected to the negative input end of the inverter circuit module; The two ends of the filter capacitor C1 are connected in parallel to the two output ends of the reactor Ld1; The collector of the IGBT module VT1 is connected to the positive output terminal of the reactor Ld1, and the emitter of the IGBT module VT1 is connected to the collector of the IGBT module VT2; The emitter of the IGBT module VT2 is connected to the negative output terminal of the reactor Ld1; The collector of the IGBT module VT3 is connected to the positive output terminal of the reactor Ld1, and the emitter of the IGBT module VT3 is connected to the collector of the IGBT module VT4; The emitter of the IGBT module VT4 is connected to the negative output terminal of the reactor Ld1; The intersection of the IGBT module VT1 and the IGBT module VT2 is connected to an input end of the reactor Ld2; The intersection of the IGBT module VT3 and the IGBT module VT4 is connected to the other input end of the reactor Ld2; The two output ends of the reactor Ld2 serve as the two output ends of the inverter circuit module.

6. The dual-frequency switching IGBT power supply according to claim 4, characterized in that: The resonant capacitor C2, the resonant capacitor C3 and the inverter circuit module are arranged in the same cabinet.

7. The dual-frequency switching IGBT power supply according to claim 4, characterized in that: The switch K1, the switch K2, the switch K3, the switch K4, the resonant capacitor C2 and the resonant capacitor C3 are arranged in the same cabinet.

8. The dual-frequency switching IGBT power supply according to claim 1, characterized in that: The rectifier circuit module includes a rectifier diode D.

9. The dual-frequency switching IGBT power supply according to claim 1, characterized in that: The second resonant frequency is 25% to 45% of the first resonant frequency.

10. The dual-frequency switching IGBT power supply according to claim 9, characterized in that: The second resonant frequency is 30% of the first resonant frequency.

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