CN206821037U

CN206821037U - A kind of induction furnace three phase low frequency power control

Info

Publication number: CN206821037U
Application number: CN201720673766.5U
Authority: CN
Inventors: 王永宾; 计宏
Original assignee: Xian University of Science and Technology
Current assignee: Xian University of Science and Technology
Priority date: 2017-06-12
Filing date: 2017-06-12
Publication date: 2017-12-29
Anticipated expiration: 2027-06-12

Abstract

The utility model discloses a kind of induction furnace three phase low frequency power control, including microcontroller and frequency-variable module, the frequency-variable module includes three-phase transformer and frequency conversion main circuit, the input of microcontroller is terminated with protection circuit, synchronous shaping and pulse fault detection circuit, the output of microcontroller is terminated with pulse control circuit, protection circuit includes voltage protection circuit, current protecting circuit and open-phase protection circuit, voltage protection circuit includes voltage detection module, excess voltage protection and low-voltage protection circuit, current protecting circuit includes current detection module and current foldback circuit, pulse control circuit includes pulse shaping circuit, pulse amplifying circuit, closed loop regulation circuit and given integrating circuit.The utility model is simple in construction, the active power of increase input induction furnace, energy-saving, and without hearth electrode in induction furnace, it is easy for installation, while mixing power is strong so that temperature distribution is uniform in induction furnace, improves the production efficiency of induction furnace.

Description

A kind of induction furnace three phase low frequency power control

Technical field

The utility model belongs to low-frequency power control technology field, and in particular to a kind of three phase low frequency power supply control of induction furnace Device processed.

Background technology

Induction furnace is the electric furnace for making material heat or melt using the Induction Heating effect of material, and induction furnace is adopted at present With industrial-frequency alternating current and dc source.There is molten steel component using the induction furnace of industrial-frequency alternating current and temperature is easily controllable, casting In gas is low, free from environmental pollution with the content of field trash, the advantages that saving the energy and improving working condition, but power frequency sense Stove is answered some shortcomings to be also present：First, the power factor of industrial-frequency alternating current is relatively low, so reactive loss is larger, increase electric energy disappears Consume and efficiency is low；Second, industrial-frequency alternating current stirs that impulse force is excessive, and increase molten steel not only reduces refining effect to the scouring force of furnace lining Fruit and crucible life can be reduced；3rd, industrial frequency AC makes that induction furnace programming rate is slower, and consumption electric power is more, caused dirt Dye is more；Using the induction furnace of dc source, the inclined arc of DC current is than more serious, and cold and hot area's difference is big, and temperature is difficult in induction furnace Uniformly；In addition, often making induction furnace burner hearth furnace wall hang up unfused cold burden because radiating surface is small, crucible diameter reduces, and productivity ratio declines； In addition, dc source power reguirements must have bottom to do anode, fixed body of heater, it is difficult to which installation, maintenance is inconvenient, cost is high. Therefore, a kind of a kind of induction furnace three phase low frequency power control simple in construction, cost is low, increase input are nowadays lacked The active power of induction furnace, it is energy-saving, and without hearth electrode in induction furnace, it is easy for installation, meanwhile, mixing power is strong so that sensing In-furnace temperature is evenly distributed, improves the production efficiency of induction furnace.

Utility model content

Technical problem to be solved in the utility model is to be directed to above-mentioned deficiency of the prior art, there is provided one kind sensing Stove three phase low frequency power control, its is simple in construction, reasonable in design, and cost is low, the active power of increase input induction furnace, It is energy-saving, and without hearth electrode in induction furnace, it is easy for installation, meanwhile, mixing power is strong so that and temperature distribution is uniform in induction furnace, The production efficiency of induction furnace is improved, using effect is good, is easy to promote the use of.

In order to solve the above technical problems, the technical solution adopted in the utility model is：A kind of induction furnace three phase low frequency electricity Source control device, it is characterised in that：The frequency-variable module of three phase low frequency power supply, the change are provided including microcontroller and for induction furnace Frequency module includes three-phase transformer and connects with three-phase transformer output end and power frequency supply is converted to the frequency conversion of low-frequency power Main circuit, the input of the microcontroller is terminated with protection circuit, synchronous shaping and pulse fault detection circuit, described micro- The output of controller is terminated with the pulse control circuit being controlled to frequency conversion main circuit, and the protection circuit includes voltage protection Circuit, current protecting circuit and open-phase protection circuit, the voltage protection circuit include voltage detection module and examined with voltage Excess voltage protection and low-voltage protection circuit that module output end connects are surveyed, the current protecting circuit includes current detecting Module and the current foldback circuit to connect with the current detection module output end, the pulse control circuit include pulse shaping Circuit, the pulse amplifying circuit to connect with pulse shaping circuit output end, the closed loop tune to connect with pulse shaping circuit input Economize on electricity road and the given integrating circuit to connect with closed loop regulation circuit input, the current detection module and closed loop regulation circuit Connect, the input of the pulse shaping circuit connects with the output end of microcontroller, the synchronous shaping, current detecting The input of module, voltage detection module and open-phase protection circuit connects with the output end of three-phase transformer, the frequency conversion master The input of circuit and pulse fault detection circuit connects with the output end of pulse amplifying circuit.

A kind of above-mentioned induction furnace three phase low frequency power control, it is characterised in that：The pulse shaping circuit bag Include chip TC787.

A kind of above-mentioned induction furnace three phase low frequency power control, it is characterised in that：The pulse fault detection electricity Road includes chip SN7407N, chip TLP521 and triode Q1, the chip SN7407N the 1st pin and pulse amplifying circuit Output end connect, the 2nd pin of the chip SN7407N connects with chip TLP521 the 2nd pin, the chip TLP521 The 1st pin connect through resistance R31 with 5V power output ends, the 4th pin of the chip TLP521 divides two-way, all the way through resistance R28 connects with 12V power output ends, and another way connects through resistance R34 with triode Q1 base stage；The current collection of the triode Q1 Two-way is divided in pole, connects all the way through resistance R32 with microcontroller, another way connects with commutation diode D4 anode；The rectification Diode D4 negative electrode connects with 12V power output ends, and the emitter stage of the triode Q1 and chip TLP521 the 3rd pin are equal Ground connection.

A kind of above-mentioned induction furnace three phase low frequency power control, it is characterised in that：The excess voltage protection, Low-voltage protection circuit and current foldback circuit include comparator LM311.

A kind of above-mentioned induction furnace three phase low frequency power control, it is characterised in that：The given integrating circuit bag Include model LM324 amplifier L4 and amplifier L5, the amplifier L5 inverting input to be grounded through resistance R26, the amplifier L5 In-phase input end divide two-way, connect all the way through resistance R23 with swept resistance R22 sliding end, the one of another way and resistance R20 End connects；A fixing end of the swept resistance R22 divides two-way, connects all the way through resistance R21 with 15V power output ends, separately The negative electrode with voltage-regulator diode D1 connects all the way；Another fixing end of the swept resistance R22 and voltage-regulator diode D2 sun Pole connects, and the anode of the voltage-regulator diode D1 connects with voltage-regulator diode D2 negative electrodes, the output end and resistance of the amplifier L5 R24 one end connects, and the other end of the resistance R24 divides two-way, the inverting input phase all the way through resistance R25 and amplifier L4 Connect, another way connects with commutation diode D3 anode；The negative electrode of the commutation diode D3 and swept resistance R33 sliding end Connect, a fixing end of the swept resistance R33 divides two-way, connects all the way through resistance R29 with -15V power output ends, another Road connects with commutation diode D5 negative electrode；Another fixing end of the swept resistance R33 is defeated through resistance R30 and 15V power supplys Go out end to connect, the plus earth of the commutation diode D5, the in-phase input end of the amplifier L4 is grounded through resistance R27, described Amplifier L4 output end divides three tunnels, and the other end with resistance R20 connects all the way, and another way is anti-phase through electric capacity C11 and amplifier L4's Input connects, and the 3rd tunnel is the signal output part of given integrating circuit.

A kind of above-mentioned induction furnace three phase low frequency power control, it is characterised in that：The closed loop regulation circuit bag Include model LM358 amplifier L6, amplifier L7, amplifier L8 and amplifier L9, the amplifier L6 five tunnels of in-phase input end point, first Road connects through resistance R56 with 15V power output ends, and the second tunnel connects with resistance R50 one end, the 3rd tunnel and the one of resistance R47 End connects, and the 4th tunnel is grounded through resistance R40, and the 5th tunnel connects with resistance R37 one end；The inverting input warp of the amplifier L6 Resistance R54 is grounded, and three tunnels of output end point of the amplifier L6, the resistance R41 and electric capacity C17 being concatenated all the way and amplifier L6's is same Phase input connects, and another way connects through electric capacity C16 with amplifier L6 in-phase input end, the 3rd tunnel and swept resistance R51 cunning Moved end connects；The other end of the resistance R37 divides two-way, connects all the way through resistance R35 with 15V power output ends, another way warp Resistance R36 is grounded；The fixing end ground connection of the swept resistance R51, another fixing end and the electricity of the swept resistance R51 Resistance R48 one end connects, three tunnels of in-phase input end point of the amplifier L7, and the other end with resistance R48 connects all the way, another way Connect with resistance R61 one end, the 3rd tunnel is grounded through resistance R38；The inverting input of the amplifier L7 is grounded through resistance R60, Four tunnels of the output end of the amplifier L7 point, the first via connect through resistance R39 with amplifier L7 in-phase input end, the second tunnel and rectification Diode D6 negative electrode connects, and the 3rd tunnel connects through resistance R49 with pulse shaping circuit, the 4th tunnel and the one of swept resistance R55 Individual fixing end connects；The anode of the commutation diode D6 divides two-way, and the in-phase input end with amplifier L7 connects all the way, another way Connect with commutation diode D7 negative electrode, the anode of the commutation diode D7 connects with swept resistance R55 sliding end, described Swept resistance R55 another fixing end connects through resistance R62 with 15V power output ends, the in-phase input end of the amplifier L9 Divide two-way, be grounded all the way through resistance R69, another way connects through resistance R67 with the output end of current detection module；The amplifier L9 Inverting input divide two-way, all the way through resistance R65 be grounded, another way through resistance R58 be grounded；The output end of the amplifier L9 point Three tunnels, resistance R59, electric capacity C21 and electric capacity C18 all the way through parallel connection connect with amplifier L9 inverting input, another way and electricity Resistance R64 one end connects, and the 3rd tunnel connects with resistance R50 one end；The in-phase input end of the amplifier L8 connects through resistance R63 Ground, the inverting input of the amplifier L8 divide two-way, and the other end with resistance R64 connects all the way, another way and the one of resistance R68 End connects；The connection end of the other end of the resistance R68 and the resistance R47 other end and the signal output part of given integrating circuit Connect, the output end of the amplifier L8 divides two-way, the anti-phase input of resistance R72 and electric capacity C22 and amplifier L8 all the way through parallel connection End connects, and another way connects with a swept resistance R66 fixing end；Another fixing end ground connection of the swept resistance R66, The sliding end of the swept resistance R66 connects with the resistance R61 other end.

A kind of above-mentioned induction furnace three phase low frequency power control, it is characterised in that：The synchronous shaping bag The in-phase input end for including amplifier LM324 and chip TLP181, the amplifier LM324 is grounded through resistance R52, the amplifier LM324 Inverting input connect with resistance R46 one end, the other end of the resistance R46 divides two-way, all the way with resistance R45 one end Connect, another way is grounded through electric capacity C19；The other end of the resistance R45 divides two-way, all the way through variable resistor R44 and three phase transformations The output end of depressor connects, and another way is grounded through electric capacity C20；The output end of the amplifier LM324 divides two-way, all the way through resistance R53 connects with amplifier LM324 in-phase input end, and another way connects through resistance R43 with chip TLP181 the 1st pin；It is described Chip TLP181 the 2nd pin ground connection, the 4th pin of the chip TLP181 connect through resistance R42 with 5V power output ends, institute The 3rd pin for stating chip TLP181 divides two-way, is grounded all the way through resistance R57, and another way connects with microcontroller.

A kind of above-mentioned induction furnace three phase low frequency power control, it is characterised in that：The open-phase protection circuit bag The in-phase input end for including amplifier LM124, the amplifier LM124 connects through resistance R79 with swept resistance R81 sliding end, described A swept resistance R81 fixing end connects through resistance R78 with 5V power output ends, and another of the swept resistance R81 is solid Fixed end is grounded, and the inverting input of the amplifier LM124 connects through resistance R74 with swept resistance R76 sliding end, the slip A resistance R76 fixing end divides two-way, and one end with resistance R71 connects all the way, and another way is grounded through electric capacity C23；The cunning Dynamic resistance R76 another fixing end ground connection, the other end of the resistance R71 divide two-way, all the way with commutation diode D9 the moon Pole connects, and another way connects with commutation diode D8 negative electrode, the plus earth of the commutation diode D9, the pole of rectification two Pipe D8 anode connects by resistance R70, resistance R73 and resistance R75 in parallel with the output end of three-phase transformer, the amplifier Base stage of the LM124 output end through resistance R77 and triode Q2 connects, the grounded emitter of the triode Q2, three pole Pipe Q2 colelctor electrode divides two-way, connects all the way through resistance R80 with 5V power output ends, another way connects with microcontroller.

A kind of above-mentioned induction furnace three phase low frequency power control, it is characterised in that：The microcontroller bag monolithic Machine, DSP microcontrollers or ARM microcontroller.

The utility model has advantages below compared with prior art：

1st, the utility model is by setting protection circuit, including voltage protection circuit, current protecting circuit and open-phase protection Circuit, when the failures such as overvoltage, under-voltage, overcurrent and phase shortage occurs in three-phase transformer, microprocessor control pulse shaping stops Pulse signal is only produced, cut-out frequency conversion main circuit output three phase low frequency power supply, realizes the protection to IGCT in frequency conversion main circuit.

2nd, the utility model is by setting pulse shaping circuit and pulse amplifying circuit, by caused by pulse shaping circuit Pulse signal is handled by pulse amplifying circuit, reduces the output current of pulse amplifying circuit, but increases pulse power, so that Pulse signal after amplification meets the needs that IGCT reliably triggers in frequency conversion main circuit, and by setting pulse fault detection electricity The pulse signal that road exports to pulse amplifying circuit detects, and avoids the loss of pulse signal, ensures brilliant in frequency conversion main circuit Brake tube provides three phase low frequency power supply by accurately and reliably triggering and conducting for induction furnace.

3rd, the utility model sets closed loop regulation circuit, and the output voltage Setting signal for giving integrating circuit is adjusted as closed loop The input signal on economize on electricity road, feedback signal of the current signal that current detection module collects as closed loop regulation circuit, passes through The adjustment control of closed loop regulation circuit and output voltage signal, had both met the need of work of pulse shaping circuit negative logic, and can The three phase low frequency power supply that the pulse signal for exporting pulse shaping circuit exports frequency conversion main circuit has good closed loop current stabilization Effect, meet the needs that high-accuracy stable electric current exports in induction furnace production process.

4th, ac voltage signal is shaped to synperiodic square-wave signal by the utility model by setting synchronous shaping Microcontroller is sent into, when microcontroller captures the rising edge of square-wave signal, produces interrupt requests as pulse shaping circuit Starting point, guarantee is added in frequency conversion main circuit the trigger pulse of IGCT and is added in frequency conversion main circuit on IGCT anode circuit Voltage be consistent in frequency and phase, ensure IGCT normally.

5th, the utility model is by setting frequency conversion main circuit to provide three phase low frequency power supply for induction furnace, by the work of 50Hz frequencies Frequency power is changed into the low-frequency power of 0.05Hz~5Hz frequencies, and 1/10~1/ when short net reactance is reduced to power frequency power supply 1000, because short net reactance reduces, power factor improves so that the active power increase of defeated people to induction furnace.

6th, the utility model is powered because of low-frequency power, easy for installation without hearth electrode in induction furnace, and induction furnace molten steel heating When thermal source distribution, the distribution of mixing power and electromagnetic pressure born of molten steel determined by the frequency of alternating magnetic field, frequently The more low then thermal source permeability of rate is better, the forced convertion that electromagnetic agitation is formed, and is being changed according to the height of frequency, frequency Lower, the electromagnetic pressure in electromagnetic force is smaller, drives the mixing power of molten steel flow in induction furnace big, and makes molten steel heating fast, steel Liquid temperature degree is uniform, so as to shorten smelting time, improves the production efficiency of induction furnace.

In summary, simple in construction, reasonable in design, cost is low, the active power of increase input induction furnace, energy-saving, And without hearth electrode in induction furnace, it is easy for installation, meanwhile, mixing power is strong so that temperature distribution is uniform in induction furnace, improves induction furnace Production efficiency, using effect is good, is easy to promote the use of.

Below by drawings and examples, the technical solution of the utility model is described in further detail.

Brief description of the drawings

Fig. 1 is schematic block circuit diagram of the present utility model.

Fig. 2 is the circuit theory diagrams that the utility model pulse fault detects circuit.

Fig. 3 is the circuit theory diagrams of the utility model closed loop regulation circuit.

Fig. 4 is the circuit theory diagrams that the utility model gives integrating circuit.

Fig. 5 is the circuit theory diagrams of the utility model synchronous shaping.

Fig. 6 is the circuit theory diagrams of the utility model open-phase protection circuit.

1-microcontroller；2-three-phase transformer；3-frequency conversion main circuit；

4-induction furnace；5-voltage detection module；6-synchronous shaping；

7-pulse shaping circuit；8-pulse amplifying circuit；9-excess voltage protection；

10-closed loop regulation circuit；11-give integrating circuit；12-low-voltage protection circuit；

13-current detection module；14-current foldback circuit；15-open-phase protection circuit；

16-pulse fault detects circuit.

Embodiment

As shown in figure 1, the utility model includes microcontroller 1 and the frequency conversion mould of three phase low frequency power supply is provided for induction furnace 4 Block, the frequency-variable module include three-phase transformer 2 and connect with the output end of three-phase transformer 2 and power frequency supply is converted into low frequency The frequency conversion main circuit 3 of power supply, the input of the microcontroller 1 are terminated with protection circuit, synchronous shaping 6 and pulse fault inspection Slowdown monitoring circuit 16, the output of the microcontroller 1 are terminated with the pulse control circuit being controlled to frequency conversion main circuit 3, the guarantor Protection circuit includes voltage protection circuit, current protecting circuit and open-phase protection circuit 15, and the voltage protection circuit includes voltage Detection module 5 and the excess voltage protection 9 and low-voltage protection circuit 12 to connect with the output end of voltage detection module 5, institute Stating current protecting circuit includes current detection module 13 and the overcurrent protection to connect with the output end of current detection module 13 electricity Road 14, the pulse amplifying electricity that the pulse control circuit includes pulse shaping circuit 7, connected with the output end of pulse shaping circuit 7 Road 8, the closed loop regulation circuit 10 to connect with the input of pulse shaping circuit 7 and connect with the input of closed loop regulation circuit 10 to Constant volume parallel circuit 11, the current detection module 13 connect with closed loop regulation circuit 10, the input of the pulse shaping circuit 7 Connect with the output end of microcontroller 1, the synchronous shaping 6, current detection module 13, voltage detection module 5 and phase shortage Output end of the input of protection circuit 15 with three-phase transformer 2 connects, frequency conversion main circuit 3 and pulse fault the detection electricity Output end of the input on road 16 with pulse amplifying circuit 8 connects.

In the present embodiment, frequency conversion main circuit 3 is AC-AC frequency conversion main circuit, by controlling IGCT in frequency conversion main circuit 3 It is turned on and off realizing the change of current and changes group, from the low-frequency power that the power frequency supply of 50Hz frequencies is changed into 0.05Hz~5Hz frequencies, And short net reactance is reduced to 1/10~1/1000 during power frequency power supply, because short net reactance reduces, power factor improves so that Active power increase of the defeated people to induction furnace 4.

In the present embodiment, frequency conversion main circuit 3 is that induction furnace 4 provides three phase low frequency power supply, and induction furnace 4 is interior without hearth electrode, peace Dress is convenient, and the distribution of mixing power and electromagnetic pressure born of thermal source distribution during 4 molten steel heating of induction furnace, molten steel by The frequency of alternating magnetic field is determined that the more low then thermal source permeability of frequency is better, the forced convertion that electromagnetic agitation is formed, be also according to Changing according to the height of frequency, frequency is lower, and the electromagnetic pressure in electromagnetic force is smaller, and molten steel flow stirs in driving induction furnace 4 It is big to mix power, and makes molten steel heating fast, molten steel temperature is uniform, so as to shorten smelting time, improves the production efficiency of induction furnace 4.

In the present embodiment, by setting protection circuit to include voltage protection circuit, current protecting circuit and open-phase protection electricity Road, when the failures such as overvoltage, under-voltage, overcurrent and phase shortage occurs in three-phase transformer 2, microcontroller 1 controls pulse shaping 7 to stop Pulse signal is only produced, cut-out frequency conversion main circuit 3 exports three phase low frequency power supply, realizes the guarantor to IGCT in frequency conversion main circuit 3 Shield.

In the present embodiment, the pulse shaping circuit 7 includes chip TC787.

As shown in Fig. 2 in the present embodiment, the pulse fault detection circuit 16 includes chip SN7407N, chip TLP521 With triode Q1, the 1st pin of the chip SN7407N connects with the output end of pulse amplifying circuit 8, the chip SN7407N the 2nd pin connects with chip TLP521 the 2nd pin, the 1st pin of the chip TLP521 through resistance R31 with 5V power output ends connect, and the 4th pin of the chip TLP521 divides two-way, all the way through resistance R28 and 12V power output end phases Connect, another way connects through resistance R34 with triode Q1 base stage；The colelctor electrode of the triode Q1 divides two-way, all the way through resistance R32 connects with microcontroller 1, and another way connects with commutation diode D4 anode；The negative electrode and 12V of the commutation diode D4 Power output end connects, and the emitter stage of the triode Q1 and chip TLP521 the 3rd pin are grounded.

In the present embodiment, by setting pulse shaping circuit 7 and pulse amplifying circuit 8, produced by pulse shaping circuit 7 Pulse signal handled by pulse amplifying circuit 8, when reduce pulse amplifying circuit 8 output current, second, to pulse form The pulse power that pulse is exported into circuit 7 is amplified, so that the pulse signal after amplification meets IGCT in frequency conversion main circuit 3 The needs reliably triggered.

In the present embodiment, entered by the pulse signal for setting pulse fault detection circuit 16 to export pulse amplifying circuit 8 Row detection, the loss of pulse signal is avoided, ensure that IGCT can be by reliable triggering and conducting in frequency conversion main circuit 3.

In the present embodiment, the excess voltage protection 9, low-voltage protection circuit 12 and current foldback circuit 14 include Comparator LM311.

As shown in figure 4, in the present embodiment, the given integrating circuit 11 includes model LM324 amplifier L4 and amplifier L5, the amplifier L5 inverting input are grounded through resistance R26, and the in-phase input end of the amplifier L5 divides two-way, all the way through electricity Resistance R23 connects with swept resistance R22 sliding end, and another way connects with resistance R20 one end；The one of the swept resistance R22 Individual fixing end divides two-way, connects all the way through resistance R21 with 15V power output ends, another way and voltage-regulator diode D1 negative electrode phase Connect；Another fixing end of the swept resistance R22 connects with voltage-regulator diode D2 anode, the sun of the voltage-regulator diode D1 Pole connects with voltage-regulator diode D2 negative electrodes, and the output end of the amplifier L5 connects with resistance R24 one end, the resistance R24's The other end divides two-way, connects all the way through resistance R25 with amplifier L4 inverting input, another way and commutation diode D3 anode Connect；The negative electrode of the commutation diode D3 connects with swept resistance R33 sliding end, and one of the swept resistance R33 is solid Two-way is divided in fixed end, connects all the way through resistance R29 with -15V power output ends, another way connects with commutation diode D5 negative electrode； Another fixing end of the swept resistance R33 connects through resistance R30 with 15V power output ends, the commutation diode D5's Plus earth, the in-phase input end of the amplifier L4 are grounded through resistance R27, three tunnels of output end point of the amplifier L4, all the way with The resistance R20 other end connects, and another way connects through electric capacity C11 with amplifier L4 inverting input, and the 3rd tunnel is to definite integral The signal output part of circuit 11.

As shown in figure 3, in the present embodiment, the closed loop regulation circuit 10 includes model LM358 amplifier L6, amplifier Five tunnels of L7, amplifier L8 and amplifier L9, the amplifier L6 in-phase input end point, the first via is through resistance R56 and 15V power output ends Connecting, the second tunnel connects with resistance R50 one end, and the 3rd tunnel connects with resistance R47 one end, and the 4th tunnel is grounded through resistance R40, 5th tunnel connects with resistance R37 one end；The inverting input of the amplifier L6 is grounded through resistance R54, and the amplifier L6's is defeated Go out the tunnels of Duan Fen tri-, the resistance R41 and electric capacity C17 being concatenated all the way connect with amplifier L6 in-phase input end, and another way is through electric capacity C16 connects with amplifier L6 in-phase input end, and the 3rd tunnel connects with swept resistance R51 sliding end；The resistance R37's is another Two-way is divided at end, connects all the way through resistance R35 with 15V power output ends, and another way is grounded through resistance R36；The swept resistance R51 Fixing end ground connection, another fixing end of the swept resistance R51 connects with resistance R48 one end, the amplifier L7 In-phase input end point three tunnels, all the way the other end with resistance R48 connect, another way connects with resistance R61 one end, the 3rd tunnel It is grounded through resistance R38；The inverting input of the amplifier L7 is grounded through resistance R60, four tunnels of output end point of the amplifier L7, the Connect all the way through resistance R39 with amplifier L7 in-phase input end, the second tunnel connects with commutation diode D6 negative electrode, the 3rd road warp Resistance R49 connects with pulse shaping circuit 7, and the 4th tunnel connects with a swept resistance R55 fixing end；The commutation diode D6 anode divides two-way, and the in-phase input end with amplifier L7 connects all the way, and another way connects with commutation diode D7 negative electrode, institute The anode for stating commutation diode D7 connects with swept resistance R55 sliding end, another fixing end warp of the swept resistance R55 Resistance R62 connects with 15V power output ends, and the in-phase input end of the amplifier L9 divides two-way, is grounded all the way through resistance R69, separately Connect all the way through resistance R67 with the output end of current detection module 13；The inverting input of the amplifier L9 divides two-way, passes through all the way Resistance R65 is grounded, and another way is grounded through resistance R58；The output end of the amplifier L9 point three tunnels, resistance R59 all the way through parallel connection, Electric capacity C21 and electric capacity C18 connect with amplifier L9 inverting input, and another way connects with resistance R64 one end, the 3rd tunnel and electricity Resistance R50 one end connects；The in-phase input end of the amplifier L8 is grounded through resistance R63, the inverting input point of the amplifier L8 Two-way, all the way the other end with resistance R64 connect, another way connects with resistance R68 one end；The other end of the resistance R68 Connect with the connection end of the resistance R47 other end with the signal output part of given integrating circuit 11, the output end of the amplifier L8 Divide two-way, the resistance R72 and electric capacity C22 all the way through parallel connection connect with amplifier L8 inverting input, another way and swept resistance A R66 fixing end connects；Another fixing end ground connection of the swept resistance R66, the sliding end of the swept resistance R66 Connect with the resistance R61 other end.

In the present embodiment, the input using the output voltage Setting signal of given integrating circuit 11 as closed loop regulation circuit 10 Signal, feedback signal of the current signal that current detection module 13 collects as closed loop regulation circuit 10, is adjusted by closed loop The adjustment control of circuit 10 and output voltage signal, had both met the need of work of pulse shaping circuit negative logic, and can makes pulse The three phase low frequency power supply that forming the pulse signal of circuit output exports frequency conversion main circuit 3 has good closed loop steady flow result, Meet the needs that high-accuracy stable electric current exports in the production process of induction furnace 4.

As shown in figure 5, in the present embodiment, the synchronous shaping 6 includes amplifier LM324 and chip TLP181, described Amplifier LM324 in-phase input end is grounded through resistance R52, the inverting input of the amplifier LM324 and resistance R46 one end phase Connect, the other end of the resistance R46 divides two-way, and one end with resistance R45 connects all the way, and another way is grounded through electric capacity C19；It is described The resistance R45 other end divides two-way, connects all the way through variable resistor R44 with the output end of three-phase transformer 2, another way is through electric capacity C20 is grounded；The output end of the amplifier LM324 divides two-way, connects all the way through resistance R53 with amplifier LM324 in-phase input end, Another way connects through resistance R43 with chip TLP181 the 1st pin；The 2nd pin ground connection of the chip TLP181, the chip TLP181 the 4th pin connects through resistance R42 with 5V power output ends, and the 3rd pin of the chip TLP181 divides two-way, all the way It is grounded through resistance R57, another way connects with microcontroller 1.

In the present embodiment, by setting synchronous shaping 6, ac voltage signal is shaped to synperiodic square wave and believed Number, microcontroller 1 is sent into, when microcontroller 1 captures the rising edge of square-wave signal, produces interrupt requests as pulse shaping The starting point of circuit 7, guarantee are added in the trigger pulse of IGCT in frequency conversion main circuit 3 and are added in IGCT sun in frequency conversion main circuit 3 Voltage on polar circuit is consistent in frequency and phase, ensures IGCT normally.

As shown in fig. 6, in the present embodiment, the open-phase protection circuit 15 includes amplifier LM124, the amplifier LM124's In-phase input end connects through resistance R79 with swept resistance R81 sliding end, and a fixing end of the swept resistance R81 is through electricity Resistance R78 connects with 5V power output ends, and another fixing end ground connection of the swept resistance R81, the amplifier LM124's is anti-phase Input connects through resistance R74 with swept resistance R76 sliding end, and a fixing end of the swept resistance R76 divides two-way, and one Road connects with resistance R71 one end, and another way is grounded through electric capacity C23；Another fixing end ground connection of the swept resistance R76, The other end of the resistance R71 divides two-way, and the negative electrode with commutation diode D9 connects all the way, and another way is with commutation diode D8's Negative electrode connects, the plus earth of the commutation diode D9, the resistance R70 of the anode process parallel connection of the commutation diode D8, Resistance R73 and resistance R75 connect with the output end of three-phase transformer 2, and the output end of the amplifier LM124 is through resistance R77 and three Pole pipe Q2 base stage connects, and the grounded emitter of the triode Q2, the colelctor electrode of the triode Q2 divides two-way, all the way through electricity Resistance R80 connects with 5V power output ends, and another way connects with microcontroller 1.

In the present embodiment, the bag single-chip microcomputer of microcontroller 1, DSP microcontrollers or the ARM microcontroller.

For the utility model in use, microcontroller 1 enters working condition, microcontroller 1 controls pulse shaping circuit 7 to produce Pulse signal, pulse signal caused by pulse shaping circuit 7 are amplified by pulse amplifying circuit 8, and pulse fault detects The pulse signal that circuit 16 exports to pulse amplifying circuit 8 detects, and avoids the loss of pulse signal, ensures the arteries and veins after amplification The normal work of signal control frequency conversion main circuit 3 is rushed, the power frequency supply that three-phase transformer 2 exports is converted to by frequency conversion main circuit 3 Three phase low frequency power supply, three phase low frequency power supply is provided for induction furnace 4, the power frequency supply of 50Hz frequencies is changed into 0.05Hz~5Hz frequencies The low-frequency power of rate, and short net reactance be reduced to power frequency power supply when 1/10~1/1000, due to short net reactance reduce, power Factor improves so that the active power increase of defeated people to induction furnace, also, pulse shaping circuit 7 can be controlled by microcontroller 1 Different pulse signals is produced, it is different with amplitude so as to change the frequency of low-frequency power caused by frequency conversion main circuit 3, ensure sensing Heat is evenly distributed in stove 4, has both made load melting most fast, makes molten steel reduction most fast again, improves the production efficiency of induction furnace 4.For During induction furnace 4 provides three phase low frequency power supply, current detection module 13 detects the electric current of the output of three-phase transformer 2 in real time, And the current signal collected is sent into current foldback circuit 14 and closed loop regulation circuit 10, by current foldback circuit 14 Judge, when the output overcurrent signal of current foldback circuit 14 is to microcontroller 1, microcontroller 1 controls pulse shaping circuit 7 to stop Produce pulse signal；Voltage detection module 5 detects the voltage of the output of three-phase transformer 2, and the voltage signal that will be collected in real time It is sent into excess voltage protection 9 and low-voltage protection circuit 12, by excess voltage protection 9 and low-voltage protection circuit 12 Judgement, when the output over-voltage signal of excess voltage protection 9 to microcontroller 1 or low-voltage protection circuit 12 output owe electricity When pressing signal to microcontroller 1, microcontroller 1 controls pulse shaping circuit 7 to stop producing pulse signal；Open-phase protection circuit 15 The output of detection three-phase transformer 2 whether there is phase shortage in real time, when open-phase protection circuit 15 detects that the output end of three-phase transformer 2 is deposited In phase shortage, and when default phase signal is sent to microcontroller 1, microcontroller 1 controls pulse shaping circuit 7 to stop producing pulse Signal, cut-out frequency conversion main circuit 3 export three phase low frequency power supply, realize the protection to IGCT in frequency conversion main circuit 3, this practicality is newly Type is simple in construction, the active power of increase input induction furnace, energy-saving, and ensures that heat is evenly distributed in induction furnace, both made It is load melting most fast, make molten steel reduction most fast again, improve the production efficiency of induction furnace, using effect is good, is easy to promote the use of.

It is described above, only it is preferred embodiment of the present utility model, not the utility model is imposed any restrictions, every Any simple modification, change and the equivalent structure change made according to the utility model technical spirit to above example, still Belong in the protection domain of technical solutions of the utility model.

Claims

A kind of 1. induction furnace three phase low frequency power control, it is characterised in that：Including microcontroller (1) and it is induction furnace (4) provide three phase low frequency power supply frequency-variable module, the frequency-variable module include three-phase transformer (2) and with three-phase transformer (2) Output end connects and power frequency supply is converted to the frequency conversion main circuit (3) of low-frequency power, and the input of the microcontroller (1) terminates There are protection circuit, synchronous shaping (6) and pulse fault detection circuit (16), the output of the microcontroller (1) to be terminated with The pulse control circuit being controlled to frequency conversion main circuit (3), the protection circuit include voltage protection circuit, current protection electricity Road and open-phase protection circuit (15), the voltage protection circuit include voltage detection module (5) and with voltage detection module (5) The excess voltage protection (9) and low-voltage protection circuit (12) that output end connects, the current protecting circuit are examined including electric current Survey module (13) and the current foldback circuit (14) to connect with the current detection module (13) output end, the Pulse Width Control electricity Road includes pulse shaping circuit (7), the pulse amplifying circuit (8) to connect with pulse shaping circuit (7) output end and pulse shaping The closed loop regulation circuit (10) and connect with closed loop regulation circuit (10) input electric to definite integral that circuit (7) input connects Road (11), the current detection module (13) connect with closed loop regulation circuit (10), the input of the pulse shaping circuit (7) Connect with the output end of microcontroller (1), the synchronous shaping (6), current detection module (13), voltage detection module (5) connect with output end of the input with three-phase transformer (2) of open-phase protection circuit (15), the frequency conversion main circuit (3) Output end of the input of circuit (16) with pulse amplifying circuit (8) is detected with pulse fault to connect.
2. according to a kind of induction furnace three phase low frequency power control described in claim 1, it is characterised in that：The pulse Forming circuit (7) includes chip TC787.
3. according to a kind of induction furnace three phase low frequency power control described in claim 2, it is characterised in that：The pulse Failure detector circuit (16) includes chip SN7407N, chip TLP521 and triode Q1, the 1st pin of the chip SN7407N Connect with the output end of pulse amplifying circuit (8), the 2nd pin phase of the 2nd pin and chip TLP521 of the chip SN7407N Connect, the 1st pin of the chip TLP521 connects through resistance R31 with 5V power output ends, the 4th pin of the chip TLP521 Divide two-way, connect all the way through resistance R28 with 12V power output ends, another way connects through resistance R34 with triode Q1 base stage； The colelctor electrode of the triode Q1 divides two-way, connects all the way through resistance R32 with microcontroller (1), another way and commutation diode D4 anode connects；The negative electrode of the commutation diode D4 connects with 12V power output ends, the emitter stage of the triode Q1 and Chip TLP521 the 3rd pin is grounded.
4. according to a kind of induction furnace three phase low frequency power control described in claim 1 or 2, it is characterised in that：It is described Excess voltage protection (9), low-voltage protection circuit (12) and current foldback circuit (14) include comparator LM311.
5. according to a kind of induction furnace three phase low frequency power control described in claim 1 or 2, it is characterised in that：It is described Given integrating circuit (11) includes model LM324 amplifier L4 and amplifier L5, and the inverting input of the amplifier L5 is through resistance R26 is grounded, and the in-phase input end of the amplifier L5 divides two-way, connected all the way through resistance R23 with swept resistance R22 sliding end, Another way connects with resistance R20 one end；A fixing end of the swept resistance R22 divides two-way, all the way through resistance R21 with 15V power output ends connect, and another way connects with voltage-regulator diode D1 negative electrode；Another of the swept resistance R22 is fixed End connects with voltage-regulator diode D2 anode, and the anode of the voltage-regulator diode D1 connects with voltage-regulator diode D2 negative electrodes, described Amplifier L5 output end connects with resistance R24 one end, and the other end of the resistance R24 divides two-way, all the way through resistance R25 and fortune The inverting input for putting L4 connects, and another way connects with commutation diode D3 anode；The negative electrode of the commutation diode D3 with Swept resistance R33 sliding end connects, and a fixing end of the swept resistance R33 divides two-way, all the way through resistance R29 and -15V Power output end connects, and another way connects with commutation diode D5 negative electrode；Another fixing end warp of the swept resistance R33 Resistance R30 connects with 15V power output ends, the plus earth of the commutation diode D5, the in-phase input end of the amplifier L4 It is grounded through resistance R27, three tunnels of output end point of the amplifier L4, the other end with resistance R20 connects all the way, and another way is through electric capacity C11 connects with amplifier L4 inverting input, and the 3rd tunnel is the signal output part of given integrating circuit (11).
6. according to a kind of induction furnace three phase low frequency power control described in claim 5, it is characterised in that：The closed loop Regulation circuit (10) includes model LM358 amplifier L6, amplifier L7, amplifier L8 and amplifier L9, and the amplifier L6's is same mutually defeated Entering the tunnels of Duan Fen five, the first via connects through resistance R56 with 15V power output ends, and the second tunnel connects with resistance R50 one end, and the 3rd Road connects with resistance R47 one end, and the 4th tunnel is grounded through resistance R40, and the 5th tunnel connects with resistance R37 one end；The amplifier L6 inverting input is grounded through resistance R54, three tunnels of output end point of the amplifier L6, the resistance R41 and electricity being concatenated all the way Hold C17 with amplifier L6 in-phase input end to connect, another way connects through electric capacity C16 with amplifier L6 in-phase input end, the 3rd tunnel Connect with swept resistance R51 sliding end；The other end of the resistance R37 divides two-way, defeated through resistance R35 and 15V power supplys all the way Go out end to connect, another way is grounded through resistance R36；The fixing end ground connection of the swept resistance R51, the swept resistance R51 Another fixing end connect with resistance R48 one end, three tunnels of the in-phase input end of the amplifier L7 point, all the way with resistance R48 The other end connect, another way connects with resistance R61 one end, the 3rd tunnel through resistance R38 be grounded；The amplifier L7's is anti-phase defeated Enter end to be grounded through resistance R60, four tunnels of output end point of the amplifier L7, homophase input of the first via through resistance R39 Yu amplifier L7 End connects, and the second tunnel connects with commutation diode D6 negative electrode, and the 3rd tunnel connects through resistance R49 with pulse shaping circuit (7), the Four tunnels connect with a swept resistance R55 fixing end；The anode of the commutation diode D6 divides two-way, all the way with amplifier L7's In-phase input end connects, and another way connects with commutation diode D7 negative electrode, and the anode of the commutation diode D7 is with sliding electricity Resistance R55 sliding end connects, and another fixing end of the swept resistance R55 connects through resistance R62 with 15V power output ends, The in-phase input end of the amplifier L9 divides two-way, is grounded all the way through resistance R69, another way is through resistance R67 and current detection module (13) output end connects；The inverting input of the amplifier L9 divides two-way, is grounded all the way through resistance R65, another way is through resistance R58 is grounded；Three tunnels of the output end of the amplifier L9 point, resistance R59, electric capacity C21 and electric capacity C18 and amplifier L9 all the way through parallel connection Inverting input connect, another way connects with resistance R64 one end, and the 3rd tunnel connects with resistance R50 one end；The amplifier L8 in-phase input end is grounded through resistance R63, and the inverting input of the amplifier L8 divides two-way, another with resistance R64 all the way End connects, and another way connects with resistance R68 one end；The connection end of the other end of the resistance R68 and the resistance R47 other end Connect with the signal output part of given integrating circuit (11), the output end of the amplifier L8 divides two-way, the resistance all the way through parallel connection R72 and electric capacity C22 connect with amplifier L8 inverting input, and another way connects with a swept resistance R66 fixing end；It is described Swept resistance R66 another fixing end ground connection, the sliding end of the swept resistance R66 connect with the resistance R61 other end.
7. according to a kind of induction furnace three phase low frequency power control described in claim 1 or 2, it is characterised in that：It is described Synchronous shaping (6) includes amplifier LM324 and chip TLP181, the in-phase input end of the amplifier LM324 connect through resistance R52 Ground, the inverting input of the amplifier LM324 connect with resistance R46 one end, and the other end of the resistance R46 divides two-way, and one Road connects with resistance R45 one end, and another way is grounded through electric capacity C19；The other end of the resistance R45 divides two-way, and passing through all the way can Become resistance R44 with the output end of three-phase transformer (2) to connect, another way is grounded through electric capacity C20；The output of the amplifier LM324 Two-way is divided at end, connects all the way through resistance R53 with amplifier LM324 in-phase input end, another way is through resistance R43 and chip TLP181 The 1st pin connect；The 2nd pin ground connection of the chip TLP181, the 4th pin of the chip TLP181 through resistance R42 with 5V power output ends connect, and the 3rd pin of the chip TLP181 divides two-way, are grounded all the way through resistance R57, another way and micro-control Device (1) processed connects.
8. according to a kind of induction furnace three phase low frequency power control described in claim 1 or 2, it is characterised in that：It is described Open-phase protection circuit (15) includes amplifier LM124, and the in-phase input end of the amplifier LM124 is through resistance R79 and swept resistance R81 Sliding end connect, a fixing end of the swept resistance R81 connects through resistance R78 with 5V power output ends, the slip Resistance R81 another fixing end ground connection, cunning of the inverting input through resistance R74 Yu swept resistance R76 of the amplifier LM124 Moved end connects, and a fixing end of the swept resistance R76 divides two-way, and one end with resistance R71 connects all the way, and another way is through electricity Hold C23 ground connection；Another fixing end ground connection of the swept resistance R76, the other end of the resistance R71 divides two-way, all the way with Commutation diode D9 negative electrode connects, and another way connects with commutation diode D8 negative electrode, the anode of the commutation diode D9 Ground connection, the anode of the commutation diode D8 is by resistance R70, resistance R73 and resistance R75 and three-phase transformer (2) in parallel Output end connect, the base stage of the amplifier LM124 output end through resistance R77 and triode Q2 connects, the triode Q2 Grounded emitter, the colelctor electrode of the triode Q2 divides two-way, connected all the way through resistance R80 with 5V power output ends, another Road connects with microcontroller (1).
9. according to a kind of induction furnace three phase low frequency power control described in claim 1 or 2, it is characterised in that：It is described Microcontroller (1) bag single-chip microcomputer, DSP microcontrollers or ARM microcontroller.