Summary of the invention
Technical problem to be solved by this invention is, a kind of electromagnetic heating precise temperature control system is provided, for liquid heats and can carry out accurate temperature control to being heated.
For solving the problems of the technologies described above, the invention provides a kind of electromagnetic heating precise temperature control system, comprise electromagnetic heating temperature control device, solenoid, temperature transducer, liquid conducting pipes and sealed valve, wherein:
Described electromagnetic heating temperature control device output AC high frequency electric is to described solenoid;
The two ends of described liquid conducting pipes link to each other with described sealed valve;
Described sealed valve is provided with the first storehouse and the second storehouse, during heating, is heated liquid and enters and derive from described the first storehouse; Described the second storehouse is provided with the screw thread keyhole, is used for by screw that the screwed plug of described heating element heater is fastening;
The sealing part of described sealed valve is provided with flange, further is provided with the antiseep rubber blanket between two cylinder sheets of described flange, and described flange is provided with six fastener holes, is used for by the fastened by screw antiseep;
Described solenoid is used for producing magnetic field by electric current and produces eddy current at the liquid that is heated of liquid conducting pipes, thereby realizes that solenoid carries out Electromagnetic Heating to being heated liquid;
Described temperature transducer, be configured in to be heated on the liquid and link to each other with described electromagnetic heating temperature control device, be used for surveying the temperature that is heated liquid, described electromagnetic heating temperature control device gathers the temperature value that described temperature transducer records, and exchanging the output of high frequency electric according to this thermometric value adjustment, described adjustment comprises the size of adjusting the output AC high frequency electric or adjusts break-make.
Described electromagnetic heating temperature control device preferably includes: a microprocessor module MCU, temperature detecting module, interchange high frequency output module, AC/DC ac-dc converter circuit module and a power supply, wherein:
Described power supply is used to described electromagnetic heating temperature control device that electric energy is provided, and exporting the alternating current of inputting to described AC/DC ac-dc converter circuit module converts is direct current;
Described interchange high frequency output module under described microprocessor module MCU control, is converted to the required interchange high frequency electric of Electromagnetic Heating with direct current and exports described solenoid to;
Described temperature detecting module is connected with temperature transducer on being heated liquid, for detection of the thermometric value that obtains temperature transducer, and this thermometric value is fed back to described microprocessor module MCU;
Described microprocessor module MCU is according to the thermometric value that receives, and the output current size of described interchange high frequency output module is adjusted in control, perhaps adjusts as required whether stop or starting the output AC high frequency electric.
Described solenoid can be to adopt the coiling of refractory metal wire rod to form, and material is to be easy to produce the metal wire rod that eddy current is given birth to heat under electromagnetic induction.
The alternating current of described power supply input is preferably 220 volts 50 hertz electric main; Described interchange high frequency output module, the high-frequency alternating current after direct current changed is the high-frequency alternating current of 18KHz to 30KHz.
Described interchange high frequency output module is pulse frequency modulated PFM control circuit preferably.
Described microprocessor module MCU can be according to the thermometric value that receives, when the output current size of described interchange high frequency output module is adjusted in control, adopt the interchange high-frequency output voltage of directly adjusting interchange high frequency output module to realize, or adopt the resistance of directly adjusting power supply to cooperate AC/DC AC/DC modular converter to realize.
Described microprocessor module MCU can be according to the thermometric value that receives, the output current size of described interchange high frequency output module is adjusted in control, when realizing temperature control, adoption rate-integral-derivative controller PID mode perhaps adopts from setting mode and carries out temperature control.
Described electromagnetic heating temperature control device can further comprise:
Touch-screen is used for whole heating temperature-control system being controlled by touch-screen for the user, and the user checks current heating-up temperature by interface input control parameter;
Programmable computer controller PCC is used for exporting the control information that the user inputs by touch-screen to described microprocessor module MCU, realizes that the user is to the control of whole temperature control system;
Warning circuit when temperature value reaches default alarm conditions, carries out alarm prompt to the user.
Described touch-screen and programmable computer controller PPC preferred disposition have a DC power supplier, and the direct current of output 24V is to touch-screen and PPC module for power supply.
Described Electromagnetic Heating accurate temperature controller device can adopt when setting mode carries out temperature control, and when certainly adjusting beginning, the sampling time with PID is made as 0 in advance; Input filter constant default value is 0%; Differential gain default value is 50%.
Electromagnetic heating precise temperature control system of the present invention, adopt solenoid to heat being heated liquid, overcome the defective of the larger wayward heating of conventional heater thermal inertia, and provide temperature transducer Real-Time Monitoring heating-up temperature, after calculating controlled quentity controlled variable, adopt the control procedure of certainly adjusting with the PID combination, certainly adjust after the beginning, trend towards design temperature after can fast temperature being adjusted.
The specific embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing the present invention is described in further detail.
As shown in Figure 1, show the composition schematic diagram of this electromagnetic heating precise temperature control system, comprised electromagnetic heating temperature control device, solenoid, temperature transducer, liquid conducting pipes and sealed valve, wherein:
Described electromagnetic heating temperature control device output AC high frequency electric is to described solenoid;
The two ends of described liquid conducting pipes and described sealed valve (belong to the understandable frame for movement of those skilled in the art, specifically do not draw among the figure) link to each other;
Described sealed valve is provided with the first storehouse and the second storehouse (belong to the understandable frame for movement of those skilled in the art, specifically do not draw among the figure), during heating, is heated liquid and enters and derive from described the first storehouse; Described the second storehouse is provided with the screw thread keyhole, is used for by screw that the screwed plug of described heating element heater is fastening;
The sealing part of described sealed valve is provided with flange and (belongs to the understandable frame for movement of those skilled in the art, specifically do not draw among the figure), further be provided with the antiseep rubber blanket between two cylinder sheets of described flange, described flange is provided with six fastener holes, is used for by the fastened by screw antiseep;
Described solenoid is used for producing magnetic field by electric current and produces eddy current at the liquid that is heated of liquid conducting pipes, thereby realizes that solenoid carries out Electromagnetic Heating to being heated liquid;
Described temperature transducer, be configured in to be heated on the liquid and link to each other with described electromagnetic heating temperature control device, be used for surveying the temperature that is heated liquid, described electromagnetic heating temperature control device gathers the temperature value that described temperature transducer records, and exchanging the output of high frequency electric according to this thermometric value adjustment, described adjustment comprises the size of adjusting the output AC high frequency electric or adjusts break-make.
Sealed valve (belongs to the understandable frame for movement of those skilled in the art, specifically do not draw among the figure) have two kinds, a kind of sealing part is provided with flange, further be provided with the antiseep rubber blanket between two cylinder sheets of flange, flange is provided with six fastener holes, is used for by the fastening antiseep of waterproof holding screw.Another kind of sealed valve only is provided with a storehouse, is not provided with second storehouse.
A kind of embodiment is: an end of liquid conducting pipes is connected with the sealed valve that is provided with inlet, and the other end is connected with the sealed valve that is provided with liquid outlet; Sealed valve is provided with the first storehouse and the second storehouse, and liquid outlet or inlet are arranged at respectively on the first storehouse of sealed valve, and during heating, liquid enters and derives from described the first storehouse; The second storehouse is provided with the screw thread keyhole, is used for by the waterproof holding screw screwed plug of heater coil is fastening.
Another kind of embodiment is: an end of liquid conducting pipes is connected with the sealed valve that is provided with inlet, and the other end is connected with the sealed valve that is provided with liquid outlet; The sealed valve that is provided with liquid outlet is provided with the first storehouse and the second storehouse, and liquid outlet is arranged on the first storehouse of sealed valve, and during heating, liquid is derived from described the first storehouse; The second storehouse is provided with the screw thread keyhole, is used for by the waterproof holding screw screwed plug of heating element heater is fastening; The sealing part in the first storehouse of sealed valve is provided with flange, further is provided with the antiseep rubber blanket between two cylinder sheets of described flange, and described flange is provided with six fastener holes, is used for by the fastening antiseep of waterproof holding screw; Be provided with on the sealed valve of inlet flange and the second storehouse are not set, only be provided with the first storehouse, liquid outlet is arranged on the first storehouse of sealed valve, and during heating, liquid enters from described the first storehouse.
As shown in Figure 1, described electromagnetic heating temperature control device comprises a microprocessor module MCU, and a temperature detecting module exchanges the high frequency output module, AC/DC change-over circuit module, power supply.Wherein:
Described power supply is used to described electromagnetic heating temperature control device that electric energy is provided, and civil power is after the power supply input, and exporting described AC/DC change-over circuit module converts to is direct current, and direct current exports to and exchanges the high frequency output module;
Described interchange high frequency output module is converted to the required interchange high frequency electric of Electromagnetic Heating with direct current and exports described solenoid under microprocessor module MCU control.
Described temperature detecting module is connected with temperature transducer on being heated liquid, for detection of the thermometric value that obtains temperature transducer, and this thermometric value is fed back to described microprocessor module MCU.Described microprocessor module MCU is according to the thermometric value that receives, and the output current size of described interchange high frequency output module is adjusted in control, perhaps adjusts as required whether stop or starting the output AC high frequency electric.
Described microprocessor module MCU comes whole heating system is added thermal control as the control core of whole electromagnetic heating system, wherein disposes the software systems for accurate temperature control.
Described solenoid can adopt the coiling of refractory metal wire rod to form, and determines according to the instrument size heating surface (area) (HS.Described temperature transducer, the position of configuration are in the center of each district's calandria, with the calandria contact.Be heated liquid, be used for induction heating when solenoid passes through high-frequency ac, material is to be easy to produce the metal material that eddy current is given birth to heat, for example iron material or Steel material or their alloy materials separately under electromagnetic induction.
After electromagnetic heating precise temperature control system enters normal operation, under the control of electromagnetic heating temperature control device, the measurement temperature that obtains according to feedback is adjusted high frequency electric and is adjusted the change coil heats, enters this real-time adjustment duty of thermometric-heating-thermometric-heat or stop heating.
As shown in Figure 2, provided a specific embodiment based on electromagnetic heating precise temperature control system shown in Figure 1.
Among the embodiment shown in Figure 2, be heated and dispose 3 solenoids on the liquid for carrying out Electromagnetic Heating to being heated the liquid different piece, each the solenoid heating position that is heated liquid disposes a temperature transducer, and temperature transducer is PT100 herein.Described power unit adopts 220 volts 50 hertz electric main power supply, civil power is inputed in the microcomputer heating controller that is made of MCU, under the control of microcomputer heating controller, civil power is carried out after AC/DC (ac/dc) is converted to direct current, again the high-frequency ac voltage of direct current utilization interchange high frequency output module converts for 18KHz inputed in a plurality of solenoids, be used for heating being heated liquid.Among this embodiment, also comprise a user control interface, it is touch-screen, be used for whole heating temperature-control system being controlled by touch-screen for the user, the user can pass through interface input control parameter, the temperature value of for example setting or start or stop heating by touch-screen, the user also can check current heating-up temperature by touch-screen.The user exports described microcomputer heating controller (i.e. microprocessor module MCU corresponding shown in Figure 1) by the control information (comprising temperature control instruction and design temperature value information) of touch-screen input to by a PCC (programmingcomputer controller) programmable computer controller module, thereby realizes that the user is to the control of whole temperature control system.Described touch-screen and PPC programmable computer controller block configuration have a DC power supplier, and the direct current of output 24V is to touch-screen and PPC module for power supply.
As shown in Figure 3, the fundamental diagram that has shown whole electromagnetic heating temperature control system.
At first, with 220KV, the alternating current of 50Hz becomes direct current to electromagnetic heating temperature control device by inner AC/DC change-over circuit (can be current rectifying and wave filtering circuit herein); Pass through again PFM (pulse frequency modulated, Pulse Frequency Modulation) control circuit (being interchange high frequency output module shown in Figure 1) and convert direct current to the 18-30KHz high frequency voltage; The electric current that changes at a high speed can be different according to material by solenoid, produce the different wave length magnetic field that changes at a high speed, when the magnetic line of force in the magnetic field when being heated metal object, can in being heated metal object, produce countless little eddy current, be heated metal object itself and generate heat at a high speed thereby make.In heating process, measurement is heated the temperature value of liquid, carry out temperature controlled temperature control module (being MCU module shown in Figure 1) and adjust PFM (pulse frequency modulated according to dut temperature, Pulse Frequency Modulation) the interchange high-frequency heating size of current of control circuit output, predeterminable alarm conditions once also, when temperature value reaches alarm conditions, also can carry out alarm prompt to the user.MCU carries out temperature control can pass through ratio (Proportion)-integration (Integral)-differential (Derivative) controller PID and carry out temperature control, or controls through carry out temperature from adjusting.
As shown in Figure 4, having provided the circuit diagram of the power unit shown in Figure 1 of electromagnetic heating precise temperature control system. this power supply adapts to temperature control system to power requirement by the adjustment of resistance.When namely adjust exchanging high frequency output, can adjust to realize to exchanging the high frequency output module, also again under the MCU module controls, realize by adjusting the resistance that civil power is converted to galvanic power supply.Concrete employing is above-mentioned which kind of adjustment mode, can select as required.
Micro-processor MCV module shown in Figure 1 is used for the adjustment of major control temperature, is the core temperature control module.Fig. 5 and Fig. 6 are the principles and structure schematic diagrames of an A/D change-over circuit in the MCU module.This A/D change-over circuit becomes data signal with the current conversion that power supply provides, and calculates the output controlled quentity controlled variable according to control algolithm again.Bidirectional triode thyristor shown in Figure 6 adopts the method for phase shift to trigger, and zero cross detection circuit detects the zero crossing of power supply A phase voltage, and the MCU control module is sent interrupt signal in the temperature control system, thereby starts timer work.Count according to controlled quentity controlled variable, after zero, send triggering signal by interface chip.Circuits for triggering send trigger impulse accordingly, and then the conducting of control silicon controlled, the temperature of adjusting device.The sampling period then, the collecting temperature data are calculated controlled quentity controlled variable according to control algolithm; Simultaneously, detect the zero cross signal of power supply A phase; A phase zero passage then causes interruption, carries out controllable silicon and triggers the phase shift processing.
As shown in Figure 7, the flow chart that has shown PID control.
At first move main program, carry out data initialization;
Judge whether to arrive the sampling time, if then further judge whether to enter from setting procedure, then directly finish if not to adjust;
Judge whether to enter from setting procedure, if then carry out from setting procedure; Execution finishes from setting procedure, then upgrades pid parameter and returns to and judge whether to carry out from adjusting, if not yet finish, then further judges whether to have finished adjustment, if do not finish, then returns to and whether then to judge the sampling time, if finished then end.
Judge not enter when setting procedure, then enter the PID branch road, carry out not divisional processing of proportional integral, judge whether afterwards to have finished adjustment, if do not finish, then return to and whether then to judge the sampling time, finish if finished then.
The present invention has following two characteristics:
1, output can be data mode D, also can be switching value form Y, can freely select when programming, as shown in Figure 6.
2, can obtain best sampling time and pid parameter value by certainly adjusting, improve control accuracy.Such as Fig. 7, shown in Figure 8.Fig. 8 has explained the PID. among Fig. 7 in detail.Fig. 9 is accurately result of temperature control.
As shown in Figure 8, shown the simulation control of PID systematic schematic diagram.Among Fig. 8, the control law of PID is as follows:
e(t)=r(t)-c(t)
u(t)=Kp[e(t)+1/Ti∫e(t)dt+TD?de(t)/dt]
Wherein, e (t) is deviation, and r (t) is set-point, and c (t) is real output value, and u (t) is controlled quentity controlled variable; Kp, Ti, TD are respectively proportionality coefficient, time of integration coefficient, derivative time coefficient.
Operation result:
1. the digital quantity form of analog output: MV=u (t).
2. switching point output: Y=T*[MV/PID exports the upper limit].Y is the interior output point of control cycle turn-on time.Increase operation output valve MV minimizing along with measured value PV is used for adding thermal control.
Described electromagnetic heating precise temperature control system when work, has from adjusting pattern.The user can select when needed from the pattern of adjusting, and makes the control parameter (sampling time, proportional gain Kp, the time of integration Ti, derivative time TD) of system's Automatic-searching the best.Certainly adjusting at first, the user is made as 0 with the control cycle (sampling time) of PID in advance.Before certainly adjusting, current mensuration temperature and environment temperature must be consistent, just can reach the best effect of adjusting.The input filter constant has the sampled value of making and changes level and smooth effect, and its default value is 0%, represents not filtering.The differential gain belongs to the LPF link, has the output valve of mitigation effect jumpy, and its default value is 50%, increases this differential gain value and will make abirritation more obvious, and the general user need not to change.
The schematic diagram of in tuning process, temperature being adjusted, as shown in Figure 9.Wherein ,+DIFF is the control temperature upper limit, and-DIFF is the control lowest temperature.After the beginning of adjusting, temperature changes according to shown in the curve, finishes the rear temperature of adjusting and trends towards design temperature, does not need to adjust when again starting heating again.