CN106862737B - A kind of the output overcurrent protection control circuit and method of plasma cutting power supply - Google Patents
A kind of the output overcurrent protection control circuit and method of plasma cutting power supply Download PDFInfo
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- CN106862737B CN106862737B CN201710165104.1A CN201710165104A CN106862737B CN 106862737 B CN106862737 B CN 106862737B CN 201710165104 A CN201710165104 A CN 201710165104A CN 106862737 B CN106862737 B CN 106862737B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K10/00—Welding or cutting by means of a plasma
- B23K10/006—Control circuits therefor
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Abstract
The invention discloses a kind of output overcurrent of plasma cutting power supply protection control circuit and method, output overcurrent protection control circuit includes：Input main power module, output inductor, high-frequency model, output detection module and control module；The input terminal of output inductor is connected to the first output end for inputting main power module, the input terminal of high-frequency model is connected to the second output terminal for inputting main power module, the first input end of output detection module is connected to the output end of output inductor, second input terminal of output detection module is connected to the output end of high-frequency model, the third output end of output detection module is connected to the first input end of control module, 4th output end of output detection module is connected to the second input terminal of control module, the output end of control module is connected to the control terminal for inputting main power module.The present invention be not only avoided that plasma cutting power supply because output electric current it is excessive break down and be avoided that protection false triggering caused by production efficiency attenuating.
Description
Technical field
The invention belongs to Arc Welding Power technical fields, more particularly, to a kind of output overcurrent of plasma cutting power supply
Protect control circuit and method.
Background technique
Plasma cutting power supply is the important component in welding equipment, is had to the development of arc welding equipment industry important
Meaning, it is closely related with the development of National Industrial.Plasma cutting power supply be a kind of output of low-voltage, high-current, dynamic response it is fast,
The high special power supply of reliability requirement.The main circuit of existing plasma cutting power supply DC converting part generallys use phase-shifting full-bridge
Topology, realization power grid are isolated with late-class circuit, it is ensured that the safety of cutting operation.Plasma cutting power supply is difficult in normal work
Exempt to cause to export electricity due to contact starting the arc under misoperation, workpiece surface out-of-flatness, contactless striking mode etc.
Flow failure.For the safe and reliable work for guaranteeing plasma cutting power supply, it is necessary to quickly, accurately when occurring to export overcurrent fault
Ground makes a response failure.
The method for mostly using current instantaneous value to protect in existing plasma cutting power supply greatly, is believed by sampled output current
Number, then via digital signal processor (DSP) with setting current protection limit value compared with after, make protection determine, then seal
Driving signal is locked, plasma cutting power supply is made to stop working.
As plasma cutting power supply switching device frequency is continuously improved, the method effect of above-mentioned current instantaneous value protection by
Gradually it is weakened.On the one hand, because switching frequency improves, the outputting inductance inductance value of phase-shifting full-bridge part is set in plasma cutting power supply
Count smaller, this is advantageously implemented the high power density of power supply, but simultaneously but also inductance becomes the rejection ability of curent change
It is weak.When load impedance mutates, curent change will more acutely, in the case where uncontrolled, it is easier to occur defeated
Overcurrent fault out.On the other hand, while switching frequency improves, due to hardware limitation or for cost consideration, system control
Frequency processed there is no promotion or be promoted not as good as switching frequency, so that switch motion number increases in the unit control period, control difficulty
Increase.
In these cases, if the protection limit value setting of current instantaneous value protection is excessive, it is easy to appear a control period
Not yet detect overcurrent, and when next control cycle detection is to overcurrent has been more than the current stress of device, can not play guarantor
Shield effect, influences the safe and reliable work of plasma cutting power supply；If the protection limit value setting of current instantaneous value protection is too small, can
Can output electric current slightly has overshoot under the adjustment effect of controller in normal work, be more than current protection limit value, occur accidentally to protect
Phenomenon greatly reduces the production efficiency of plasma cutting power supply.
Summary of the invention
In view of the drawbacks of the prior art, the purpose of the present invention is to provide a kind of output overcurrent of plasma cutting power supply guarantors
Protect control method, it is intended to solve the problems, such as that existing output current protection method can not correctly and efficiently trigger protection.
The present invention provides a kind of output overcurrents of plasma cutting power supply to protect control circuit, including：Input main power
Module, output inductor, high-frequency model, output detection module and control module；The input terminal of output inductor is connected to
The first output end of main power module is inputted, the input terminal of high-frequency model is connected to the second output terminal for inputting main power module,
The first input end of output detection module is connected to the output end of output inductor, and the second input terminal for exporting detection module connects
It is connected to the output end of high-frequency model, exports the first output end of detection module for being connected to tungsten electrode, exports the of detection module
For two output ends for being connected to for being connected to workpiece, the third output end of the output detection module is connected to the control mould
4th output end of the first input end of block, the output detection module is connected to the second input terminal of the control module, institute
The output end for stating control module is connected to the control terminal of the main power module of input.
Further, when work, the electric energy of input is converted to low-voltage direct-current electric energy by the main power input module,
And after the output inductor and high-frequency model filtering, by the output detection module to output voltage and output electricity
Stream is detected, and final output to tungsten electrode, cutting torch and workpiece carry out plasma cut work；The control module is according to described defeated
The output voltage signal and output current signal of detection module detection export the drive for controlling the main power input module out
Dynamic signal；When output overcurrent occurs, the driving signal controls the main power input module from service, to realize
Stream protection.
Further, output detection module includes：Current detection module and voltage detection module；Current detection module
First input end of the input terminal as the output detection module, the first output end of current detection module are examined as the output
Survey the first output end of module, third output end of the second output terminal of current detection module as the output detection module；
The first input end of voltage detection module is connected with the first output end of output electric current measure module, and the second of voltage detection module
Second input terminal of the input terminal as output detection module, while the also second output terminal as the output detection module, electricity
Press the first output end of detection module as the 4th output end of the output detection module.
Further, control module includes：Drive module, phase shift computing module, data acquisition module, logic synthesis mould
Block, protection recovery timer, current slope protective module, comparison module, current slope computing module and the second comparison module；It drives
The first input end of dynamic model block is connected with the first output end of integrated logic module, the second input terminal and phase shift meter of drive module
The first output end for calculating module is connected, first output end of the first output end of drive module as control module；Phase shift calculates
The first input end that the first input end of module is connected with the first input end of data acquisition module as control module, phase shift meter
Calculate second input terminal of the second input terminal of module as control module, the first output end and drive module of phase shift computing module
The second input terminal be connected；The first input end of data acquisition module is connected as control with the first input end of phase shift computing module
The first input end of molding block, the first input end phase of the first output end and current slope computing module of data acquisition module
Even, the second output terminal of data acquisition module is connected with the first input end of the second comparison module；The first of logic synthesis module
First output end of input terminal current slope protective module is connected, and the second input terminal of logic synthesis module and protection restore timing
First output end of device is connected, the first output end phase of the third input terminal of logic synthesis module and second comparison module
Even；The first input end of protection recovery timer is connected with the first output end of the current slope protective module, the protection
First output end of recovery timer is connected with the second input terminal of the logic synthesis module；The of current slope protective module
One input terminal is connected with the first output end of the comparison module, the first output end of current slope protective module and logic synthesis
The first input end of module is connected, at the same the first output end of current slope protective module with protect the first defeated of recovery timer
Enter end to be connected；The first input end of comparison module is connected with the first output end of current slope computing module, and the of comparison module
Two input terminals are that slope protects limit value km, the first output end of the comparison module and the first of the current slope protective module
Input terminal is connected；The first input end of current slope computing module is connected with the first output end of the data acquisition module, electricity
First output end of stream slope computing module is connected with the first input end of the comparison module；The first of second comparison module is defeated
Enter end to be connected with the second output terminal of data acquisition module, the second input terminal of the second comparison module is current instantaneous value protection limit
Value Ip；Data acquisition module is used to acquire the output current value I of current control periodk, it is upper one control the period output current value
Ik-1；Current slope computing module is used for the output current value I according to current control periodk, it is upper one control the period output electric current
Value Ik-1Calculate the current slope k of current control period；The comparison module is used for the current slope k according to current control period
Current slope protection limit value kp operation with setting obtains logical comparison result；Overcurrent protection module is according to the logical comparison knot
Fruit issues the signal whether protected；Protection recovery timer determines whether to start according to the current protection signal of overcurrent protection module
Protection restore timing, when protect recovery timer receive current protection signal when reset timing, when protection recovery timer not
Start timing when receiving current protection signal, protects recovery clocking value N to reach protection when current slope and restore timing threshold value a
When, it issues protection and restores signal；Logic synthesis module is used to restore signal to current slope protection signal and protection to carry out logic
Comprehensive descision does not issue driving locking signal, otherwise sends out when current slope protects invalidating signal and protection recovery signal is effective
Locking signal is driven out；Sending or block of the drive module for driving, when drive module receives logic synthesis module
When the driving locking signal of sending, drive module block driving does not issue driving signal, is otherwise calculated according to phase shift computing module
Obtained phase shifting angle generates corresponding driving signal and driving signal is sent to the control terminal of the main power module of input, drives
Move the main power module work of the input.
The present invention also provides a kind of output overcurrents of plasma cutting power supply to protect control method, includes the following steps：
(1) the output current value I of current control period is acquiredkWith the output current value I in a upper control periodk-1, and according to
Formula k=Ik-Ik-1Calculate the current slope k of current control period；
(2) judge whether the output current value of current control period is greater than output current protection limit value Ip, if so, carrying out
Driving block, makes phase-shifting full-bridge module from service；If it is not, being then transferred to step (3)；
(3) judge whether the current slope k of current control period is greater than current slope protection limit value kp, if so, carrying out
Driving block, makes phase-shifting full-bridge module from service；If it is not, being then transferred to step (4)；
(4) judge that current slope protection restores whether clocking value is greater than protection recovery timing threshold value, if so, restoring to drive
It is dynamic, the phase shift signal output drive signal obtained according to phase shift computing module, and N=0；If it is not, then carrying out driving block, make to move
Phase full-bridge modules stop working, and N=N+1.
In embodiments of the present invention, current slope protection limit value kp allows maximum current climbing to determine according to system, and one
As determine allow maximum current climbing after take certain allowance, be taken as allow maximum current climbing 0.85-0.95.Electric current
Slope protects limit value related with current slope variation when outputting inductance inductance value, switching frequency, control frequency and normal work.It is defeated
Inductance inductance value is bigger out, and current slope when breaking down is smaller；Under same switch frequency, control frequency is higher, required setting
Current slope protection limit value can be bigger；Under identical control frequency, switching frequency is higher, the current slope protection of required setting
Limit value is smaller；And current slope value of the current slope protection limit value set when having to be larger than normal work, it reduces accidentally protect as far as possible
Protect probability.
In embodiments of the present invention, current instantaneous value protection limit value Ip should be true according to the maximum allowable operating current point of system
It is fixed, certain allowance is generally taken after determining maximum allowable operating current, is taken as the 0.85-0.95 of maximum allowable operating current.This
Invention protects the protection control method combined with current slope using current instantaneous value protection, protects in current slope and ensures system
Under the premise of safety of uniting, it can suitably relax current instantaneous value protection limit value.Protection restores timing threshold value should be according to electric after protection
Stream recovery time determines that generally 10-100 control period, i.e., it is 10-100 that the described protection, which restores timing threshold value a,.It protects extensive
The selection of multiple timing threshold value is related with outputting inductance, and outputting inductance is bigger, and electric current is got over the time required to dropping to zero after protecting
Long, the timing threshold value of required setting is longer.
Contemplated above technical scheme through the invention determines due to using current slope compared with prior art
Condition, so can be more easier to prejudge out output electric current overcurrent fault, it is ensured that the safe and reliable work of plasma cutting power supply
Make；Meanwhile can suitably increase the protection limit value of current instantaneous value protection in conjunction with current instantaneous value protection, reduce the general of accidentally protection
Rate improves production efficiency.Further, since exporting overcurrent protection caused by the reasons such as maloperation, workpiece surface out-of-flatness, it is not necessarily to
Machine is restarted, only cutting work need to can be re-started by the waiting in several control periods, production effect is greatly improved
Rate.
Detailed description of the invention
Fig. 1 is the modular structure schematic diagram of plasma cutting power supply provided in an embodiment of the present invention；
Fig. 2 is that a kind of output overcurrent of plasma cutting power supply provided in an embodiment of the present invention protects the realization of control method
Flow chart；
Fig. 3 is the theoretical critical waveform diagram using trigger slope protection when guard method of the present invention；
Fig. 4 triggers the theoretical critical waveform diagram of instantaneous value protection when being using guard method of the present invention；
Fig. 5 is the emulation key waveforms figure using trigger slope protection when guard method of the present invention；
Fig. 6 triggers the emulation key waveforms figure of instantaneous value protection when being using guard method of the present invention.
Wherein, SC is input ac power, and REC is high-frequency rectification module, and PSFB is phase-shifting full-bridge module, and DCL is output
Filter inductance, CD are current detection module, and VD is voltage detection module, and HFM is high-frequency model, and DRV is drive module, and PSCM is
Phase shift computing module, LSM are logic synthesis module, and PRT is that protection restores timer, and CSPM is current slope protective module, CM
For comparison module, CSCM is current slope computing module, and DCM is data acquisition module, and Drv is driving signal, and Pss is phase shift control
Signal processed, Dbs are driving locking signal, and Prs is that protection restores signal, and Cps is that current slope protects signal, and kp is current slope
Limit value is protected, k is current control period current slope, and Io is output current value, IkFor the output current value of current control period,
Ik-1For the output current value in a upper control period, Ip is output current protection limit value, and Imax is maximum allowable operating current point,
Vo is output voltage values, and Tc is the control period, and Ts is switch periods, and N is that protection restores clocking value, and a is that protection restores timing threshold
Value, kmax are to allow maximum current climbing.
1 is inputs main power module, and 2 be output inductor, and 3 be high-frequency model, and 4 be output detection module, and 5 be control
Module, 6 be tungsten electrode, and 7 be cutting torch, and 8 be workpiece, and 10 be input ac power, and 11 be high-frequency rectification module, and 12 be phase-shifting full-bridge mould
Block, 40 be current detection module, and 41 be voltage detection module, and 50 be drive module, and 51 be phase shift computing module, and 52 adopt for data
Collect module, 53 be logic synthesis module, and 54 is protect recovery timer, and 55 be current slope protective module, and 56 be comparison module,
57 be current slope computing module, and 58 be the second comparison module.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.
The present invention provides a kind of output overcurrents of plasma cutting power supply to protect control method, solves existing output electricity
Flow guard method can not correctly and efficiently trigger protection the problem of, such as in normal work false triggering protect or exporting
It can not trigger protection etc. when over current fault.
The present invention relates to a kind of output overcurrents of plasma cutting power supply to protect control circuit, including the main power module of input
1, output inductor 2, high-frequency model 3, output detection module 4 and control module 5.Input the first output of main power module 1
End inputs the second output terminal of main power module 1 for being connected to high-frequency model for being connected to 2 input terminal of output inductor
3 input terminals, 2 output end of output inductor are used to be connected to the first input end of output detection module 4, and high-frequency model 3 exports
The second input terminal for being connected to output detection module 4 is held, the first output end of output detection module 4 is for being connected to cutting torch
7, the second output terminal of output detection module 4 is for being connected to workpiece 8, and output 4 third output end of detection module is for being connected to
Control module first input end, the 4th output end of output detection module is for being connected to the second input terminal of control module, institute
Control module output end is stated for being connected to the main power module control terminal of output.
The present invention provides a kind of output overcurrents of plasma cutting power supply to protect control method, includes the following steps：
(1) output current information (the output electric current including current control period obtained according to data collecting module collected
The output current value of value and a upper control period), the output current value and upper one for calculating current control period control the defeated of period
Current slope k of the difference of current value as current control period out, i.e. k=Ik-Ik-1；Wherein, IkFor current control period
Output current value, Ik-1For the output current value in a upper control period.
(2) judge whether the output current value of current control period is greater than output current protection limit value Ip, if so, carrying out
Driving block, makes phase-shifting full-bridge module from service, current slope protective program terminates；If it is not, being then transferred to step (3)；
(3) judge whether the current slope k of current control period is greater than current slope protection limit value kp, if so, carrying out
Driving block, makes phase-shifting full-bridge module from service；If it is not, being then transferred to step (4)；
(4) judge that current slope protection restores whether clocking value N is greater than protection recovery timing threshold value a, if so, restoring to drive
It is dynamic, the phase shift signal output drive signal obtained according to phase shift computing module, meanwhile, it resets current slope protection and restores timing
Value, current slope protective program terminate；If it is not, then carrying out driving block, make phase-shifting full-bridge module from service, meanwhile, electric current
Slope protection restores clocking value N from adding, and current slope protective program terminates.
The present invention proposes a kind of output overcurrent protection control method of plasma cutting power supply, solves existing plasma and cuts
It cuts and exports the problem of electric current overcurrent protection scheme can not combine high safety reliability and high efficiency in power supply, it can
Accidentally protection probability is reduced while ensureing that plasma cutting power supply securely and reliably works, while when accidentally protecting without restarting machine
Device can work on, and production efficiency is greatly improved.
Fig. 1 shows the structural schematic diagram of plasma cutting power supply in the embodiment of the present invention, for ease of description, only shows
Part related to the embodiment of the present invention, details are as follows：
The present invention relates to a kind of output overcurrents of plasma cutting power supply to protect control circuit, including main power input module
1, output inductor 2, high-frequency model 3, output detection module 4, control module 5.Main 1 first output end of power input module with
The connection of 2 input terminal of output inductor, main 1 second output terminal of power input module are connect with 3 input terminal of high-frequency model, output filter
2 output end of wave inductance is connect with output 4 first input end of detection module, 3 output end of high-frequency model and output detection module 4 second
Input terminal connection, output 4 first output end of detection module are connect with tungsten electrode 6, output 4 second output terminal of detection module and workpiece 8
Connection, output 4 third output end of detection module are connect with 5 first input end of control module, export the 4th output end of detection module 4
It is connect with 5 second input terminal of control module, 5 output end of control module is connect with main 1 control terminal of power input module.Of the invention
Working principle is divided into power flow and signal stream two parts, and from the angle of power flow, electric energy is inputted by main power input module 1, stream
It filters, output voltage, output electric current is detected by output detection module 4, most through output inductor 2, high-frequency model 3
Output to tungsten electrode 6, cutting torch 7, workpiece 8 carries out plasma cut work eventually；From the angle of signal stream, output voltage, output electric current
Signal obtains driving signal, driving letter by 4 traffic organising module 5 of output detection module after the internal calculation of control module 5
Number stream by control module 5 flows to main power input module 1.Wherein, when output overcurrent protection does not occur, driving signal stream is positive
Normal driving signal, driving transducer work, transmits energy；When output overcurrent protection occurs, driving signal block, driving letter
Number stream does not issue signal, and converter stops working.
Wherein, main power input module 1 includes sequentially connected input ac power 10, high-frequency rectification module 11, phase shift
Full-bridge modules 12；First output end of phase-shifting full-bridge module 12 is connected to the input terminal of output inductor 2, phase-shifting full-bridge module
12 second output terminal is connected to the input terminal of high-frequency model 3.Main power input module 1 mainly transmits power flow, AC energy
Input ac power 10 flows into, and high-voltage direct-current electric energy is transformed to by high-frequency rectification module 11, using phase-shifting full-bridge module
12 are transformed to the output of low-voltage direct-current electric energy.
Wherein, output detection module 4 predominantly detects the output current signal and output voltage signal of plasma cutting power supply,
Circuit parameter is provided for the control of plasma cutting power supply.Exporting detection module 4 includes current detection module 40, voltage detecting mould
Block 41；The input terminal of the current detection module 40 is connected with the output end of output inductor 2, the current detection module 40
The first output end be connected with the first input end of voltage detection module 41, meanwhile, the first of the current detection module 40 is defeated
Outlet is connected as the first output end of the output detection module 4 with tungsten electrode 6, the third output of the current detection module 40
End is connected with the first input end of the phase shift computing module 51 of control module 5, the 4th output end of the current detection module 40
It is connected with the input terminal of the data acquisition module 52 of control module 5, the second input terminal and high frequency of the voltage detection module 41
The output end of module 3 is connected, and the first output end of the voltage detection module 41 is connected with workpiece 8, the voltage detection module
41 second output terminal is as the 4th output end of the detection module 4 and the second of the phase shift computing module 51 of control module 5
Input terminal is connected.Output detection module 4 transmits power flow and signal stream simultaneously, flows through output detection module 4 in direct current energy
Meanwhile it exporting detection module 4 and obtaining output voltage, output current signal from direct current energy.Wherein, current detection module 40 obtains
The current signal of direct current energy is taken, voltage detection module 41 obtains the voltage signal of direct current energy, while the letter that will test
Number it is transferred to control module 5.
Wherein, control module 5 is mainly used for calculating phase shifting angle according to output voltage, output current signal, and passing through output
Current signal determines whether to block driving, final output or block driving signal.Control module 5 includes drive module 50, phase shift
Computing module 51, data acquisition module 52, logic synthesis module 53, protection recovery timer 54, current slope protective module 55,
Comparison module 56, current slope computing module 57, the second comparison module 58；The input terminal and electric current of the data acquisition module 52
The second signal output end of detection module 40 is connected, and the first output end and current slope of the data acquisition module 52 calculate mould
The input terminal of block 57 is connected, the first input end phase of the second output terminal of the data acquisition module 52 and the second comparison module 58
Even, the output end of the current slope computing module 57 is connected with the first input end of comparison module 56, the comparison module 56
Output end be connected with the input terminal of current slope comparison module 55, the first output end of the current slope protective module 55 with
The input terminal that protection restores timer 54 is connected, the second output terminal and logic synthesis module of the current slope protective module 55
53 first input end is connected, the output end and the second input terminal phase of logic synthesis module 53 of the protection recovery timer 54
Even, the output end of second comparison module 58 is connected with the third input terminal of logic synthesis module 53, the logic synthesis mould
The output end of block 53 is connected with the first input end of drive module 50, the first input end and electric current of the phase shift computing module 51
First signal output end of detection module 40 is connected, the second input terminal of the phase shift computing module 51 and voltage detection module
Signal output end is connected, and the output end of the phase shift computing module 51 is connected with the second input terminal of drive module 50.
Control module 5 is mainly used for transmitting signal stream, and input is output voltage signal, output current signal, output
For driving signal.Wherein, data acquisition module 52 is acquired for circuit parameter, specifically includes the output electric current of current control period
Value Ik, it is upper one control the period output current value Ik-1；Current slope computing module 57 is used for the output according to current control period
Current value Ik, it is upper one control the period output current value Ik-1Calculate the current slope k of current control period；Comparison module 56
Logical comparison result is obtained according to the current slope k of current control period and the current slope protection limit value kp operation of setting；Electric current
Protective module 55 issues the signal whether protected according to the logical comparison result of comparison module 56；Protect 54 basis of recovery timer
The current protection signal of overcurrent protection module 55 determines whether that starting protection restores timing, when protection recovery timer receives electricity
Timing is reset when stream protection signal, starts timing when protecting recovery timer not receive current protection signal, when electric current is oblique
When rate protection recovery clocking value N reaches protection recovery timing threshold value a, protection recovery signal is issued；Logic synthesis module 53 is used for
Signal is restored to current slope protection signal and protection and carries out logic synthesis judgement, when current slope protects invalidating signal and protection
When recovery signal is effective, driving locking signal is not issued, otherwise issues driving locking signal；Hair of the drive module 50 for driving
It out or blocks, when drive module 50 receives the driving locking signal of the sending of logic synthesis module 53, drive module block is driven
It is dynamic, driving signal is not issued, corresponding driving signal is otherwise generated simultaneously according to the phase shifting angle that phase shift computing module 51 is calculated
Driving signal is sent to the control terminal of phase-shifting full-bridge module 12, driving phase-shifting full-bridge module work.
The present invention provides a kind of protection control method based on above-mentioned current slope protection circuit, this method is based on electric current
Slope realizes protection control：Output current value is first obtained, calculates the current slope of current control period, then protect with current slope
Shield limit value relatively determines whether that issuing current slope protects signal, and current slope protection signal and protection are restored signal and electric current
Instantaneous value protection signal determines whether sending driving locking signal after carrying out logic synthesis, finally issues or block drives.
The flow chart of the control method is as shown in Fig. 2, specifically include：
(1) output current information (the output electric current including current control period obtained according to data collecting module collected
The output current value of value and a upper control period), calculate the current slope k of current control period；
(2) judge whether the output current value of current control period is greater than output current protection limit value Ip, if so, carrying out
Driving block, makes phase-shifting full-bridge module from service, current slope protective program terminates；If it is not, being then transferred to step (3)；
(3) judge whether the current slope k of current control period is greater than current slope protection limit value kp, if so, carrying out
Block is driven, phase-shifting full-bridge module from service is made, meanwhile, current slope protection restores clocking value N and adds certainly by 0, every warp
It crosses a control periodic current slope protection recovery clocking value N and adds 1, current slope protective program terminates；If it is not, being then transferred to step
(4)；
(4) judge that current slope protection restores whether clocking value is greater than protection recovery timing threshold value, if so, restoring to drive
It is dynamic, the phase shift signal output drive signal obtained according to phase shift computing module, meanwhile, current slope protection restores clocking value N by 0
Beginning is from adding, and every to add 1 by a control periodic current slope protection recovery clocking value N, current slope protective program terminates；If
It is no, then driving block is carried out, phase-shifting full-bridge module from service is made, current slope protective program terminates.
Fig. 3 show the waveform diagram using slope protection when guard method of the present invention, wherein and Dbs is driving locking signal,
Ik is the output current value at kth moment, and Uk is the output voltage values at phase-shifting full-bridge module kth moment.T1-T4 moment electric current is with k1
Slope rises, and current slope is less than current slope protection limit value at this time, does not issue driving locking signal, plasma cutting power supply is just
Often work；The T4-T5 moment current slope that breaks down is increased to k2, and current slope is greater than current slope and protects limit value, hair at this time
Locking signal is driven out, and plasma cutting power supply stops working, and after waiting several control periods, protects the counting of recovery timer
Reach protection and restore timing threshold value a, protection restores, and does not issue driving locking signal, plasma cutting power supply is resumed work.
The waveform diagram of Fig. 4 instantaneous value protection when showing using guard method of the present invention.T1-T5 moment electric power with it is oblique with k3
Rate rises, and current slope is less than current slope protection value at this time, and plasma cutting power supply works normally；T5 moment current instantaneous value
Instantaneous value protection point is risen to, driving locking signal is issued, plasma cutting power supply stops working, and waits several control periods
Afterwards, protect the counting of recovery timer reach protection restore timing threshold value a, protection restore, do not issue driving locking signal, wait from
Sub- cutting power supply is resumed work.
Control method of the invention needs to design three parameters, specifically includes：
(1) current slope protects limit value
Current slope protects limit value maximum current climbing should be allowed to determine according to system, is generally determining the maximum electricity of permission
Certain allowance is taken after stream climbing, is taken as allowing the 0.85-0.95 of maximum current climbing.Current slope protects limit value and output
Current slope variation when inductance inductance value, switching frequency, control frequency and normal work is related.Outputting inductance inductance value is bigger, hair
Current slope when raw failure is smaller；Under same switch frequency, control frequency is higher, and the current slope of required setting protects limit value
It can be bigger；Under identical control frequency, switching frequency is higher, and the current slope protection limit value of required setting is smaller；And set
Current slope protection limit value has to be larger than current slope value when normal work, reduces accidentally protection probability as far as possible.Electric current is oblique herein
Rate protection limit value is taken as 60A/Tc.
(2) current instantaneous value protects limit value
Current instantaneous value protects limit value that should be determined according to the maximum allowable operating current point of system, generally determine it is maximum allowable
Certain allowance is taken after operating current, is taken as the 0.85-0.95 of maximum allowable operating current.The present invention is protected using current instantaneous value
The protection control method combined is protected with current slope, under the premise of current slope protects safeguards system safety, Ke Yishi
Limit value is protected when relaxing current instantaneous value.The limit value of current instantaneous value protection herein is taken as 130A.
(3) protection restores timing threshold value
When the overcurrent protection for occurring to trigger due to misoperation, workpiece surface out-of-flatness etc., should protect
Recovery timer restores driving after reaching timing threshold value, and plasma cutting power supply is made to work on.Protection restores timing threshold value and answers
It is determined according to electric current recovery time after protection, generally 10-100 control period, i.e., the described protection restores timing threshold value a and is
10-100.The selection that protection restores timing threshold value is related with outputting inductance, and outputting inductance is bigger, and electric current drops to after protecting
Longer the time required to zero, the timing threshold value of required setting is longer.Protection herein restores timing threshold value a and is taken as 50.
Fig. 5 is shown using current protection method of the present invention, when current slope is more than that current slope protects limit value
The waveform diagram of Shi Fasheng protection, current slope is more than current slope protection limit value and current instantaneous value is not up to current instantaneous value guarantor
Trigger protection is remained to when protecting limit value, imminent overcurrent failure is prejudged by current slope, the effective guarantee peace of system
Full reliably working；Fig. 6 is shown using current protection method of the present invention, when current instantaneous value is protected more than current instantaneous value
The waveform diagram protected when protecting limit value, current instantaneous value is more than current instantaneous value protection limit value and current slope is not up to electric current
Can correctly set out protection when slope protection limit value, this is consistent with conventional current guard method working principle, but combines electric current oblique
Rate protection can suitably relax current instantaneous value protection limit value, reduce system and a possibility that accidentally protecting occurs, it is raw to improve system
Produce efficiency.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.
Claims (6)
1. a kind of output overcurrent of plasma cutting power supply protects control circuit, which is characterized in that including：Input main power module
(1), output inductor (2), high-frequency model (3), output detection module (4) and control module (5)；
The input terminal of the output inductor (2) is connected to the first output end of the main power module (1) of input, the height
The input terminal of frequency module (3) is connected to the second output terminal of the main power module (1) of input, the output detection module (4)
First input end be connected to the output ends of the output inductor (2), the second input terminal of output detection module (4)
It is connected to the output end of the high-frequency model (3), the first output end of output detection module (4) is for being connected to tungsten electrode
(6), for the second output terminal of output detection module (4) for being connected to for being connected to workpiece (8), the output detects mould
The third output end of block (4) is connected to the first input end of the control module (5), and the 4th of output detection module (4) the
Output end is connected to the second input terminal of the control module (5), and the output end of the control module (5) is connected to the input
The control terminal of main power module (1)；
The control module (5) includes：Drive module (50), phase shift computing module (51), data acquisition module (52), logic are comprehensive
Mold block (53), protection recovery timer (54), current slope protective module (55), comparison module (56), current slope calculating
Module (57) and the second comparison module (58)；
The first input end of the drive module (50) is connected with the first output end of the integrated logic module (53), the drive
Second input terminal of dynamic model block (50) is connected with the first output end of the phase shift computing module (51), the drive module (50)
First output end of first output end as the control module (5)；
The first input end phase continuous cropping of the first input end of the phase shift computing module (51) and the data acquisition module (52)
For the first input end of the control module (5), the second input terminal of the phase shift computing module (51) is as the control mould
Second input terminal of block (5), the second of the first output end of the phase shift computing module (51) and the drive module (50) are defeated
Enter end to be connected；
The first input end phase continuous cropping of the first input end of the data acquisition module (52) and the phase shift computing module (51)
For the first input end of the control module (5), the first output end and the current slope of the data acquisition module (52)
The first input end of computing module (57) is connected, the second output terminal of the data acquisition module (52) mould compared with described second
The first input end of block (58) is connected；
First output end of current slope protective module (55) described in the first input end of the logic synthesis module (53) is connected,
Second input terminal of the logic synthesis module (53) is connected with the first output end of protection recovery timer (54), described
The third input terminal of logic synthesis module (53) is connected with the first output end of second comparison module (58)；
The first input end of protection recovery timer (54) and the first output end of the current slope protective module (55)
It is connected, the first output end and the second input terminal phase of the logic synthesis module (53) of protection recovery timer (54)
Even；
The first input end of the current slope protective module (55) is connected with the first output end of the comparison module (56), institute
The first output end for stating current slope protective module (55) is connected with the first input end of the logic synthesis module (53), simultaneously
First output end of the current slope protective module (55) is connected with the first input end of protection recovery timer (54)；
The first input end of the comparison module (56) is connected with the first output end of the current slope computing module (57), institute
State comparison module (56) the second input terminal be slope protect limit value km, the first output end of the comparison module (56) with it is described
The first input end of current slope protective module (55) is connected；
First output end phase of the first input end of the current slope computing module (57) and the data acquisition module (52)
Even, the first output end of the current slope computing module (57) is connected with the first input end of the comparison module (56)；
The first input end of second comparison module (58) is connected with the second output terminal of the data acquisition module (52), institute
The second input terminal for stating the second comparison module (58) is that current instantaneous value protects limit value Ip；
The data acquisition module (52) is used to acquire the output current value I of current control periodk, it is upper one control the period output
Current value Ik-1；
The current slope computing module (57) is used for the output current value I according to current control periodk, upper control period
Output current value Ik-1Calculate the current slope k of current control period；
The comparison module (56) is used to protect limit value kp according to the current slope k of current control period and the current slope of setting
Operation obtains logical comparison result；
The overcurrent protection module (55) issues the signal whether protected according to the logical comparison result；
Protection recovery timer (54) determines whether to start to protect according to the current protection signal of overcurrent protection module (55)
Restore timing, reset timing when protecting recovery timer to receive current protection signal, when protection recovery timer does not receive
Start timing when to current protection signal, when current slope, which is protected, to be restored clocking value N and reach protection and restore timing threshold value a, hair
Protection restores signal out；
The logic synthesis module (53) is used to restore signal to current slope protection signal and protection to carry out logic synthesis judgement,
When current slope protects invalidating signal and protection recovery signal is effective, driving locking signal is not issued, otherwise issues driving envelope
Lock signal；
Sending or block of the drive module (50) for driving, when drive module (50) receives logic synthesis module (53)
When the driving locking signal of sending, drive module block driving does not issue driving signal, otherwise according to phase shift computing module (51)
The phase shifting angle being calculated generates corresponding driving signal and driving signal is sent to the control of the main power module (1) of input
End processed drives main power module (1) work of the input.
2. output overcurrent as described in claim 1 protects control circuit, which is characterized in that when work, the main power input
The electric energy of input is converted to low-voltage direct-current electric energy by module, and is filtered through the output inductor and the high-frequency model
Afterwards, by the output detection module to output voltage and output electric current detect, final output to tungsten electrode, cutting torch and workpiece into
The work of row plasma cut；The output voltage signal and output electric current that the control module is detected according to the output detection module
Signal exports the driving signal for controlling the main power input module；When output overcurrent occurs, the driving signal control
The main power input module from service is made, to realize overcurrent protection.
3. output overcurrent as claimed in claim 1 or 2 protects control circuit, which is characterized in that the output detection module (4)
Including：Current detection module (40) and voltage detection module (41)；
First input end of the input terminal of the current detection module (40) as output detection module (4), the electric current
First output end of first output end of detection module (40) as output detection module (4), the current detection module
(40) third output end of the second output terminal as output detection module (4)；
First output end phase of the first input end of the voltage detection module (41) and the output electric current measure module (40)
Even, second input terminal of the second input terminal of the voltage detection module (41) as output detection module (4), while
As the second output terminal of output detection module (4), described in the first output end of the voltage detection module (41) is used as
Export the 4th output end of detection module (4).
4. output overcurrent as described in claim 1 protects control circuit, which is characterized in that the current slope of setting protects limit value
Kp is the 0.85-0.95 that system allows maximum current climbing, and it is that system allows maximum functional that current instantaneous value, which protects limit value Ip,
The 0.85-0.95 of electric current, it is 10-100 that protection, which restores timing threshold value,.
5. a kind of output overcurrent of plasma cutting power supply protects control method, which is characterized in that include the following steps：
(1) the output current value I of current control period is acquiredkWith the output current value I in a upper control periodk-1, and according to formula k
=Ik-Ik-1Calculate the current slope k of current control period；
(2) judge whether the output current value of current control period is greater than output current protection limit value Ip, if so, being driven
Block, makes phase-shifting full-bridge module from service；If it is not, being then transferred to step (3)；
(3) judge whether the current slope k of current control period is greater than current slope protection limit value kp, if so, being driven
Block, makes phase-shifting full-bridge module from service；If it is not, being then transferred to step (4)；
(4) judge that current slope protection restores whether clocking value is greater than protection recovery timing threshold value, if so, restoring driving, root
The phase shift signal output drive signal obtained according to phase shift computing module, and N=0；If it is not, then carrying out driving block, keep phase shift complete
Bridge module stops working, and N=N+1.
6. output overcurrent as claimed in claim 5 protects control method, which is characterized in that the current slope of setting protects limit value
Kp is the 0.85-0.95 that system allows maximum current climbing, and it is that system allows maximum functional that current instantaneous value, which protects limit value Ip,
The 0.85-0.95 of electric current, it is 10-100 that protection, which restores timing threshold value,.
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