CN109921386A - The current foldback circuit and method of pfc converter - Google Patents
The current foldback circuit and method of pfc converter Download PDFInfo
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Abstract
The present invention provides the current foldback circuit and method of a kind of pfc converter, comprising: PFC main circuit；Detection flows through the sampling module of power switch tube electric current；The over-current detection module of flow control signals should be crossed based on the electric current output phase for flowing through power switch tube；Control the PFC control module of the pulse-modulated signal duty ratio of power switch tube；Based on the drive module for crossing flow control signals and pulse-modulated signal control power switch tube on-off.When the current sampling signal of power switch tube is greater than overcurrent protection threshold value, crosses flow control signals and come into force and continue setting time, the driving signal of power switch tube is blocked when coming into force；When current sampling signal is less than overcurrent protection threshold value, and crosses flow control Signal Fail, driving signal is restored.The present invention really reflects the actual current of power switch tube, high reliablity；And open loop comparator type is used, overcurrent can be restored to work normally in time after disappearing, the EMC strong antijamming capability of system；In addition, low in cost.
Description
Technical field
The present invention relates to circuit design fields, more particularly to the current foldback circuit and method of a kind of pfc converter.
Background technique
In active power factor correction PFC (Power Factor Correction, PFC) converter,
Power switch tube (such as IGBT, Insulated Gate Bipolar Transistor, insulated gate bipolar would generally be used
Transistor), in order to protect IGBT to be unlikely to burn because electric current is excessive under overcurrent condition, can be set in traditional protection circuit
It is equipped with current detection sensor and overcurrent protection measure.
As shown in Figure 1, Rs is current sense resistor, collected current signal gives overcurrent protection route U1, U1 and is
One positive feedback locks comparator circuit, when the current signal on Rs is greater than the overcurrent protection threshold value Vref of setting, comparator
U1 output switching activity simultaneously keeps locking state, after this protection signal sends pfc controller U2 to, can make IGBT power tube QBRapidly
Shutdown, to avoid QBIt fails since electric current is excessive.
Although this route can play the role of protecting IGBT overcurrent, there is more serious defect.
Firstly, sampling resistor Rs is placed on input circuit, it is with the electric current of input circuit come the electricity on Approximate Equivalent IGBT
Stream, in fact, the two electric currents are imcomplete equivalents, the electric current on IGBT is a part of input circuit electric current.Therefore,
There can be a following two kinds situation: first, when ac input end Vin voltage is more than PFC output end voltage Vc, IGBT substantially locates
In off state, but the electric current for flowing through sampling resistor Rs is but very big, exists even if will lead to U1 overcurrent protection route in this way
It also can false triggering overcurrent protection in the case where IGBT electric current very little.Second, as diode D in PFC routeBFailure short circuit when
It waits, PFC output end electrolytic capacitor CBOn energy can pass through DBIGBT instead is filled back, the electric current on IGBT is very big at this time, but passes through
The electric current of sampling resistor Rs but very little, so that IGBT protection circuit when needing overcurrent protection but can't detect
Stream, to lose protective effect.
Secondly, generally locking route (i.e. comparator U1 using positive feedback shown in FIG. 1 in traditional overcurrent protection route
Output end connect with normal phase input end), the characteristics of this route is once triggering overcurrent protection, output will overturn and keep locking
Death situation state, until system intervention resets.Therefore, when ac input end Vin is since there are the switching overvoltage of transient state or surges
Overvoltage and when cause IGBT transient high-current occur, overcurrent protection will be triggered and PFC is caused to stop working, to lead
The EMC anti-interference ability of cause system is deteriorated.
Therefore, how to propose that a kind of high reliablity, the current foldback circuit of EMC strong antijamming capability and method have become this
One of field technical staff's urgent problem to be solved.
Summary of the invention
In view of the foregoing deficiencies of prior art, the purpose of the present invention is to provide a kind of overcurrent of pfc converter guarantors
Protection circuit and method, for solving the over-current protection method poor reliability of pfc converter in the prior art, causing system EMC anti-
The problems such as interference can be weak.
In order to achieve the above objects and other related objects, the present invention provides a kind of current foldback circuit of pfc converter, institute
The current foldback circuit for stating pfc converter includes at least:
PFC main circuit, sampling module, over-current detection module, PFC control module and drive module；
The sampling module is connected with the power switch tube of the PFC main circuit, and detection flows through the power switch tube
Electric current；
The over-current detection module is connected to the output end of the sampling module, based on the electricity for flowing through the power switch tube
Stream output phase should cross flow control signals, and the effective status for crossing flow control signals continues setting time；
The PFC control module is connected to the output end of the PFC main circuit, the output letter based on the PFC main circuit
The duty ratio of the pulse-modulated signal of number control power switch tube；
The drive module is connected to the output end of the over-current detection module and the PFC control module, based on described
It crosses flow control signals and the pulse-modulated signal controls the on-off of the power switch tube.
Optionally, the over-current detection module includes comparing unit and holding unit；The input terminal of the comparing unit point
The output end and overcurrent protection threshold value for not connecting the sampling module protect the output signal of the sampling module and the overcurrent
Shield threshold value is compared, and exports comparison result；The holding unit is connected to the output end of the comparing unit, by the mistake
The effective status of flow control signals keeps setting time.
More optionally, the holding unit includes d type flip flop；The input end of clock of the d type flip flop connects the comparison
The output end of unit, data input pin connect power supply, and reset terminal connects the output end of the PFC control module, reversed-phase output
Export the flow control signals excessively.
More optionally, the holding unit includes RC filter, and the input terminal connection of the RC filter is described relatively more single
The output end of member, the output end output of the RC filter is described to cross flow control signals.
More optionally, the RC filter includes first resistor, first capacitor and switching tube；One end of the first resistor
Power supply is connected, the other end is grounded after connecting the first capacitor, and the connecting node of the first resistor and the first capacitor connects
The drive module is connect, output is described to cross flow control signals；The paralleled power switches are described to open in the both ends of the first capacitor
The control terminal for closing pipe connects the output end of the comparing unit.
More optionally, the holding unit further includes wave detector, and the wave detector is connected to the output of the RC filter
Between end and the input terminal of the PFC control module, the wave detector generates overcurrent based on the output signal of the RC filter
Protected mode controls signal, enters overcurrent protection mode to control the PFC control module.
More optionally, the wave detector includes zener diode, second resistance and the second capacitor；The zener diode
Cathode connection is described to cross flow control signals, and anode is grounded after connecting the second resistance, the zener diode and described second
The connecting node of resistance exports the mode control signal of the PFC control module；Second capacitor is parallel to second electricity
The both ends of resistance.
More optionally, the PFC main circuit include, reactor, power switch tube and booster diode；
One end of the reactor connects the input anode of the power inverter, and the other end connects the booster diode
Anode, the booster diode cathode connection DC bus-bar voltage output end；
The power switch tube is connected to the anode of the booster diode and with reference between ground, and control terminal connects the drive
Dynamic model block.
In order to achieve the above objects and other related objects, the present invention also provides a kind of over-current protection method of pfc converter,
The over-current protection method of the pfc converter includes at least:
Overcurrent protection threshold value is set, and acquisition flows through the electric current of the power switch tube of PFC main circuit, and by the power switch
The current sampling signal of pipe is compared with the overcurrent protection threshold value；
When the current sampling signal of the power switch tube is greater than the overcurrent protection threshold value, crosses flow control signals and come into force
And continue setting time；When the mistake flow control signals come into force, the driving signal of the power switch tube is blocked；
When the current sampling signal of the power switch tube is less than the overcurrent protection threshold value, and the flow control signals excessively
When failure, the driving signal of the power switch tube is restored.
Optionally, the over-current protection method of the pfc converter further include: cross flow control signals continuously several times when described
It comes into force and when each active states continue setting time, PFC control module enters overcurrent protection mode.
As described above, the current foldback circuit and method of pfc converter of the invention, have the advantages that
1, current sampling module is placed on power switch tube by the current foldback circuit of pfc converter of the invention and method
Branch road, therefore, the electric current of acquisition and the electric current for flowing through power switch tube are the same electric currents, so that current sampling signal can be with
It is truly reflected the actual current of power switch tube completely, can avoid accidentally protecting and answering when should not protect present in traditional scheme
The case where failing protection when the protection, substantially increases the reliability of power switch tube overcurrent protection.
2, the current foldback circuit of pfc converter of the invention and method therefore can be right using open loop comparator type
The high current of moment in the power switch tube due to caused by the switching overvoltage or overvoltage surge of power grid AC power source transient state
It is protected in time, reduces PFC loss, and after having served as current vanishes, power switch tube can be restored to work normally in time again, and
It not will lead to the case where PFC stops working, substantially increase the EMC anti-interference ability of system.
3, the holding unit that flow control signals are crossed in the current foldback circuit of pfc converter of the invention and method is at low cost
It is honest and clean, high reliablity.RC filter can also be used using single d type flip flop；The base in RC filter circuit can also be passed through
Increase wave detector route on plinth, further increases the reliability of overcurrent protection route.
Detailed description of the invention
Fig. 1 is shown as the structural schematic diagram of current foldback circuit in the prior art.
Fig. 2 is shown as the structural schematic diagram of the current foldback circuit of pfc converter of the invention.
Fig. 3 is shown as a kind of structural schematic diagram of over-current detection module of the invention.
Fig. 4 is shown as a kind of flow diagram of the over-current protection method of pfc converter of the invention.
Fig. 5 is shown as the operation principle schematic diagram of the overcurrent protection electric current of pfc converter of the invention.
Fig. 6 is shown as another structural schematic diagram of over-current detection module of the invention.
Fig. 7 is shown as a kind of structural schematic diagram of holding unit of the invention.
Fig. 8 is shown as another flow diagram of the over-current protection method of pfc converter of the invention.
Component label instructions
The current foldback circuit of 1 pfc converter
11 PFC main circuits
12 sampling modules
13 over-current detection modules
131 comparing units
132 holding units
1321 d type flip flops
1322 RC filters
1323 wave detectors
14 PFC control modules
15 drive modules
Specific embodiment
Illustrate embodiments of the present invention below by way of specific specific example, those skilled in the art can be by this specification
Other advantages and efficacy of the present invention can be easily understood for disclosed content.The present invention can also pass through in addition different specific realities
The mode of applying is embodied or practiced, the various details in this specification can also based on different viewpoints and application, without departing from
Various modifications or alterations are carried out under spirit of the invention.
Please refer to Fig. 2~Fig. 8.It should be noted that diagram provided in the present embodiment only illustrates this in a schematic way
The basic conception of invention, only shown in schema then with related component in the present invention rather than package count when according to actual implementation
Mesh, shape and size are drawn, when actual implementation kenel, quantity and the ratio of each component can arbitrarily change for one kind, and its
Assembly layout kenel may also be increasingly complex.
Embodiment one
As shown in Fig. 2, the present embodiment provides a kind of current foldback circuit 1 of pfc converter, the mistake of the pfc converter
Flowing protection circuit 1 includes:
PFC main circuit 11, sampling module 12, over-current detection module 13, PFC control module 14 and drive module 15.
As shown in Fig. 2, the PFC main circuit 11 is for converting input voltage into DC bus-bar voltage.
Specifically, the PFC main circuit 11 including but not limited to booster circuit, reduction voltage circuit or step-up/step-down circuit, can root
According to needing to set different power conversion architectures, is not enumerated and be limited with the present embodiment.As shown in Fig. 2, in the present embodiment, it is described
PFC main circuit 11 is one of booster circuit, specifically includes reactor L1, power switch tube Q1 and booster diode D1.Make
Rectification circuit for a kind of implementation of the present embodiment, the input terminal connection alternating current of the PFC main circuit 11 (is not shown in figure
Show)；Parallel filtering capacitor Ci between the input anode Vi+ and input cathode Vi- of the PFC main circuit 11；The DC bus
Storage capacitor Co is connected between the output end vo and reference ground PGND of voltage, in the present embodiment, the storage capacitor Co is one
A capacitor, in actual use, the storage capacitor Co can be the series and parallel or series-parallel of multiple capacitors, not with this implementation
Example is limited.
More specifically, one end of the reactor L1 connects the input anode Vi+ of the PFC main circuit 11, the other end connects
Connect the anode of the booster diode D1, the output end vo of the cathode connection DC bus-bar voltage of the booster diode D1；Institute
The collector for stating power switch tube Q1 connects the anode of the booster diode D1, and emitter connects the sampling module 12, door
Pole connects the drive module 15.In the present embodiment, the just extremely described DC bus-bar voltage of the DC bus-bar voltage
Output end vo, the cathode of the DC bus-bar voltage are described with reference to ground PGND.
It should be noted that in the present embodiment, the power switch tube Q1 is insulated gate bipolar transistor；In reality
The type of the power switch tube Q1 can be set as needed in use, including but not limited to Metal-Oxide Semiconductor field is imitated
Transistor is answered, is adopted described in the anode of the booster diode D1, source electrode connection at this point, the drain electrode of the power switch tube Q1 connects
Egf block 12, grid connect the drive module 15.
As shown in Fig. 2, the sampling module 12 is connected with the power switch tube Q1, detection flows through the power switch tube
The electric current of Q1.
It should be noted that the connection of the sampling module 12 and power switch tube Q1 is including being directly connected to and indirectly
Connection, the sampling module 12 can detect the electric current for actually flowing through the power switch tube Q1.
Specifically, in the present embodiment, the sampling module 12 includes sampling resistor Rs.The sampling resistor Rs with it is described
Power switch tube Q1 series connection, acquisition flow through the electric current of the power switch tube Q1.In the present embodiment, the sampling resistor Rs
One end connects the emitter of the power switch tube Q1, and other end connection is described with reference to ground PGND.
It should be noted that in practical applications, the sampling resistor Rs may connect to the collection of the power switch tube Q1
Between electrode and the anode of the booster diode D1, be not limited to the present embodiment.
It should be noted that in practical applications, the sampling module 12 can also pass through it in addition to using sampling resistor
He realizes and is not limited to the present embodiment mode, such as sensor or mutual inductor are sampled, and will not repeat them here.
As shown in Fig. 2, the over-current detection module 13 is connected to the output end of the sampling module 12, it is described based on flowing through
The electric current output phase of power switch tube Q1 should cross flow control signals, when the effective status for crossing flow control signals is persistently set
Between.
Specifically, in the present embodiment, the over-current detection module 13 includes comparing unit 131 and holding unit 132.Institute
The input terminal for stating comparing unit 131 is separately connected the output end and overcurrent protection threshold value Vref of the sampling module 12, will be described
The output signal of sampling module 12 is compared with the overcurrent protection threshold value Vref, and exports comparison result.The holding is single
Member 132 is connected to the output end of the comparing unit 131, and the effective status for crossing flow control signals is kept setting time.
More specifically, in the present embodiment, the normal phase input end of the comparing unit 131 is connected to the power switch tube
The inverting input terminal of the connecting node of Q1 and sampling resistor Rs, the comparing unit 131 connects the overcurrent protection threshold value Vref；
In practical applications, the input polarity of the comparing unit 131 and the connection relationship of input signal are interchangeable, pass through phase inverter tune
Whole polarity is not limited to this embodiment with realizing identical logic.In the present embodiment, the overcurrent protection threshold value Vref
Being set as the power switch tube Q1 allows the maximum current value of work, and the overcurrent can be set as needed in actual use
Threshold value Vref is protected, is not limited to this embodiment.
More specifically, as shown in figure 3, a kind of implementation as the present embodiment, the holding unit 132 include D touching
Send out device 1321.The input end of clock CLK of the d type flip flop 1321 connects the output end of the comparing unit 131, data input pin
D connection power supply VCC, reset terminalThe pulse-modulated signal PWM of the output end output of the PFC control module 14 is connected, instead
Phase output terminalExport the flow control signals OCP excessively.
As shown in Fig. 2, the PFC control module 14 is connected to the output end vo of the PFC main circuit 11, based on described
The output signal of PFC main circuit 11 controls the duty ratio of the pulse-modulated signal PWM of the power switch tube Q1.
Specifically, the PFC control module 14 adjusts the arteries and veins of the power switch tube Q1 based on the DC bus-bar voltage
Modulated signal PWM, the PFC control module 14 can be based on hardware or software realization, will not repeat them here.
As shown in Fig. 2, the drive module 15 is connected to the over-current detection module 13 and the PFC control module 14
Output end controls the logical of the power switch tube Q1 based on the flow control signals OCP and pulse-modulated signal PWM that crosses
It is disconnected.
Specifically, the enable end crossed flow control signals OCP and connect the drive module 15, the pulse-modulated signal
PWM connects the input terminal of the drive module 15, and the output end of the drive module 15 connects the door of the power switch tube Q1
Pole.Under normal operating conditions, the drive module 15 controls the power switch tube Q1's based on the pulse-modulated signal PWM
On-off；It is described cross flow control signals OCP it is effective when, the drive module 15 is based on the flow control signals OCP that crosses for the function
Rate switching tube Q1 shutdown, and then realize overcurrent protection.
As shown in figure 4, the present embodiment also provides a kind of over-current protection method of pfc converter, the PFC based on the present embodiment
The current foldback circuit 1 of converter realizes that the over-current protection method of the pfc converter includes:
1) overcurrent protection threshold value Vref is set, and acquisition flows through the electric current of the power switch tube Q1 of PFC main circuit 11, and by institute
The current sampling signal Vsample for stating power switch tube Q1 is compared with the overcurrent protection threshold value Vref.
2) when the current sampling signal Vsample of the power switch tube Q1 is greater than the overcurrent protection threshold value Vref,
Flow control signals OCP is crossed to come into force and continue setting time；When the mistake flow control signals OCP comes into force, blocks the power and open
Close the Q1 driving signal of pipe.
3) when the current sampling signal Vsample of the power switch tube Q1 be less than the overcurrent protection threshold value Vref, and
When the failure of flow control signals OCP excessively, the driving signal of the power switch tube Q1 is restored.
Specifically include following process:
As shown in Fig. 2 and Fig. 4~Fig. 5, in the present embodiment, the overcurrent protection threshold value Vref is set as the power and opens
Closing pipe Q1 allows the maximum current value of work, the overcurrent protection threshold value Vref can be set as needed in actual use, no
It is limited with the present embodiment.The electric current for acquiring the power switch tube Q1 branch flows through the practical electricity of the power switch tube Q1
Stream, obtains current sampling signal Vsample.By the current sampling signal Vsample and the overcurrent protection threshold value Vref into
Row compares, to obtain comparison result.
As a kind of implementation of the present embodiment, as shown in Fig. 2~Fig. 5, when the pulse-modulated signal pwm signal is
When high level, the power switch tube Q1 conducting, if the current sampling signal Vsample of the power switch tube Q1 is less than at this time
The overcurrent protection threshold value Vref, then there is no overcurrent, 131 output end of comparing unit exports low level, the D triggering
Rising edge is not detected in the clock end of device 1321, therefore the d type flip flop 1321 does not trigger, the positive of the d type flip flop 1321
Output end Q exports low level, the reversed-phase output of the d type flip flop 1321Export high level, i.e., it is described to cross flow control signals
OCP is high level (crossing flow control Signal Fail), then the enable end of the drive module 15 is high level (enabled to come into force), described
Drive module 15 is in normal operating conditions.When the pulse-modulated signal PWM is high level, the power switch tube Q1 is led
It is logical, if the current sampling signal Vsample of the power switch tube Q1 is greater than the overcurrent protection threshold value Vref at this time, occur
Overcurrent, the output signal of 131 output end of comparing unit from low level jump be high level, the d type flip flop 1321 when
Zhong Duan detects rising edge, therefore the d type flip flop 1321 triggers, and the positive output end Q jump of the d type flip flop 1321 is height
Level, the reversed-phase output of the d type flip flop 1321Jump is low level, i.e., the described flow control signals OCP that crosses is low level
(crossing flow control signals to come into force), then the enable end of the drive module 15 is low level (enabled failure), the drive module 15
It is directly blocked, so that the power switch tube Q1 is turned off rapidly；After power switch tube Q1 shutdown, sample rate current disappears
It loses, the output signal of 131 output end of comparing unit jumps back low level from high level, but due to the d type flip flop
1321 be rising edge triggering, and therefore, the flow control signals OCP that crosses is constant, and low level blocked styate is kept (to cross flow control signals
Come into force and continue), until it is low level that the pulse-modulated signal PWM is by high level jump, at this point, the d type flip flop
1321 reset terminalLow level is effective, and the d type flip flop 1321 is reset, and the flow control signals OCP that crosses is from low level
Jump is high level (crossing flow control Signal Fail), then the enable end of the drive module 15 is high level (enabled to come into force), institute
Block of the flow control signals OCP releasing to the drive module 15 was stated, but the power switch tube Q1 is still in shutdown
State repeats the above logic until the arriving of next pulse-modulated signal PWM again.In the present embodiment, pass through by
The reset terminal of the d type flip flop 1321Connection pwm signal is (i.e. described to cross flow control signals come the time for setting overcurrent protection
It is low that the active states duration of OCP, which flow to the pulse-modulated signal PWM by high level jump from currently detected mistake,
Until level), it in practical applications can be as needed by the reset terminal of the d type flip flop 1321Connect different signals
The flow control signals OCP that crosses is set to come into force duration.
Embodiment two
As shown in fig. 6, the present embodiment provides a kind of current foldback circuit of pfc converter, it is different from embodiment one it
It is in the holding unit 132 includes RC filter 1322.
Specifically, as shown in fig. 6, the holding unit 132 include RC filter 1322, the RC filter 1322 it is defeated
Enter the output end that end connects the comparing unit 131, the output end output of the RC filter 1322 is described to cross flow control signals
OCP。
As a kind of implementation of the present embodiment, the RC filter 1322 includes first resistor R1, first capacitor C1
And switching tube Q2.One end of the first resistor R1 connects power supply VCC, and the other end is grounded after connecting the first capacitor C1, institute
It states first resistor R1 and connect the drive module 15 with the connecting node of the first capacitor C1, output is described to cross flow control signals
OCP.The switching tube Q2 is parallel to the both ends of the first capacitor C1, and the control terminal connection of the switching tube Q1 is described relatively more single
The output end of member 131.
The current foldback circuit of the pfc converter of the present embodiment is consistent with the other structures of embodiment one, herein not one by one
It repeats.
The present embodiment also provides a kind of over-current protection method of pfc converter, the mistake of the pfc converter based on the present embodiment
Stream protection circuit realizes, the over-current protection method of the pfc converter and embodiment one the difference is that:
When the current sampling signal Vsample of the power switch tube Q1 is greater than the overcurrent protection threshold value Vref, institute
It states power switch tube Q1 and overcurrent occurs, the comparing unit 131 exports high level, the switching tube Q2 conducting, the RC filtering
To cross flow control signals OCP by high level jump be low level (cross flow control signals come into force) for 1322 output end of device output described,
The drive module 15 is directly blocked, so that the power switch tube Q1 is turned off rapidly.After the power switch tube Q1 shutdown, adopt
The output signal of sample current vanishes, the comparing unit 131 jumps back low level, the switching tube Q2 shutdown, electricity from high level
Source is charged to the first capacitor C1 by the first resistor R1 and (crosses flow control signals and come into force and continue), crosses flow control when described
When signal OCP is gradually risen by low level to high level (cross flow control Signal Fail), the flow control signals OCP that crosses is released pair
The block of the drive module 15, control work of the drive module 15 based on the pulse-modulated signal PWM.In this implementation
In example, by adjusting time constant (the i.e. institute of the parameter regulation overcurrent protection of the first resistor R1 and the first capacitor C1
Stated the active states duration of flow control signals OCP), in the present embodiment, the shape that comes into force of the flow control signals OCP
State duration is set as the period of 2~5 pulse-modulated signal PMW, can carry out as needed in actual use
Setting.
Embodiment three
As shown in fig. 7, the present embodiment provides a kind of current foldback circuit of pfc converter, it is different from embodiment two it
It is in the holding unit 132 further includes wave detector 1323.The wave detector 1323 is connected to the RC filter 1322
Between output end and the input terminal of the PFC control module 14, the wave detector 1323 is defeated based on the RC filter 1322
Signal generates overcurrent protection mode control signal CTL out, enters overcurrent protection mode to control the PFC control module 14.
Specifically, as a kind of implementation of the present embodiment, the wave detector 1323 includes zener diode D2, second
Resistance R2 and the second capacitor C2.The zener diode D2 cathode connection it is described cross flow control signals OCP, anode connection described in
It is grounded after second resistance R2, the connecting node of the zener diode D2 and the second resistance R2 export the overcurrent protection mould
Formula controls signal CTL；The second capacitor C2 is parallel to the both ends of the second resistance R2.
The current foldback circuit of the pfc converter of the present embodiment is consistent with the other structures of embodiment two, herein not one by one
It repeats.
As shown in figure 8, the present embodiment also provides a kind of over-current protection method of pfc converter, the PFC based on the present embodiment
The current foldback circuit of converter realizes, over-current protection method and the embodiment two of the pfc converter the difference is that:
When the flow control signals OCP excessively continuously comes into force several times and each active states continue setting time, the PFC
Control module 14 enters overcurrent protection mode.
Specifically, when overcurrent does not occur for the power switch tube Q1, the flow control signals OCP that crosses is high level, institute
The zener diode D2 conducting in wave detector 1323 is stated, therefore is exported to the mould overcurrent protection of the PFC control module 14
Mode control signal CTL is also high level (normal mode of operation), and the PFC control module 14 does not do any movement.When described
When overcurrent occurs for power switch tube Q1, the flow control signals OCP that crosses is low level, the pressure stabilizing in the wave detector 1323
Diode D2 cut-off, therefore the second capacitor C2 is discharged by the second resistance R2, it is described to cross flow control if overcurrent in short-term
Signal OCP processed reverts to high level, then the overcurrent protection mode control signal CTL exported to the PFC control module 14 is still
High level (normal mode of operation), pfc controller do not do any movement；If long-time overcurrent, the second capacitor C2 passes through
The second resistance R2 continuous discharge, so that the overcurrent protection mode control signal CTL of output to the PFC control module 14 is turned over
Switch to low level (overcurrent protection mode), the PFC control module 14 enters overcurrent protection mode, institute after receiving this signal
PFC control module 14 is stated to enter after overcurrent protection mode according to different Preservation tactics, it is further on control signal to be protected
Shield movement, including but not limited to: blocking the pulse-modulated signal PWM of the power switch tube Q1, turn off the power switch tube
Q1 improves the reliability of system to avoid IGBT long-play in above-mentioned circulation overcurrent detection pattern；It can also turn off
Subsequent compression machine is closed while the power switch tube Q1；Or entire system is closed while turning off the power switch tube Q1
System；The protection to different components is further realized with this.In the present embodiment, by adjusting the second resistance R2 and described
The time constant that PFC control module 14 described in the parameter regulation of two capacitor C2 enters overcurrent protection mode is (i.e. described to cross flow control
The number of signal OCP continuously occurred).
Current sampling module is placed on power switch tube by the current foldback circuit and method of pfc converter of the invention
Branch road, and send the current sampling signal of power switch tube to comparing unit, comparing unit realizes that open circuit compares, works as electric current
When sampled signal is greater than overcurrent protection threshold value, overcurrent protection module output is low level to cross flow control signals, crosses flow control signals
The driving signal for directly blocking power switch tube, so that power switch tube turns off rapidly.After power switch tube shutdown, by
It disappears in the sampled signal on sampling module, crosses after flow control signals keep setting time and return to reset condition, eliminate to driving
The block of signal, power switch tube reenter normal operation mode.
In conclusion the present invention provides the current foldback circuit and method of a kind of pfc converter, comprising: sampling module, with
The power switch tube of PFC main circuit is connected, and detection flows through the electric current of the power switch tube；Over-current detection module is connected to institute
The output end for stating sampling module should cross flow control signals, the overcurrent based on the electric current output phase for flowing through the power switch tube
The effective status of control signal continues setting time；PFC control module is connected to the output end of the PFC main circuit, is based on institute
State PFC main circuit output signal control the power switch tube pulse-modulated signal duty ratio；Drive module is connected to
The output end of the over-current detection module and the PFC control module crosses flow control signals and the impulse modulation based on described
Signal controls the on-off of the power switch tube.Overcurrent protection threshold value is set, and acquisition flows through the power switch tube of PFC main circuit
Electric current, and the current sampling signal of the power switch tube is compared with the overcurrent protection threshold value；When the power is opened
When closing the current sampling signal of pipe greater than the overcurrent protection threshold value, crosses flow control signals and come into force and continue setting time；Work as institute
When stating flow control signals and coming into force, the driving signal of the power switch tube is blocked；When the current sample of the power switch tube
Signal is less than the overcurrent protection threshold value, and when the flow control Signal Fail excessively, the driving signal of the power switch tube is extensive
It is multiple.Current sampling module is placed on power switch tube branch road by the current foldback circuit and method of pfc converter of the invention,
Therefore, the electric current of acquisition and to flow through the electric current of power switch tube be the same electric current, so that current sampling signal signal can be complete
It is truly reflected the actual current of power switch tube entirely, accidentally protection and should when can avoid not protecting present in traditional scheme
The case where failing protection when protection, substantially increases the reliability of power switch tube overcurrent protection；And the present invention uses open loop ratio
Compared with device mode, therefore, can the high current to moment in power switch tube protected in time, after having served as current vanishes, power
Switching tube can restore to work normally in time again, not will lead to the case where PFC route stops working, substantially increase the EMC of system
Anti-interference ability；In addition, the holding unit of mistake flow control signals of the invention is low in cost, high reliablity can be touched using list D
Device is sent out, RC filter can also be used, it can also be by increasing wave detector route on the basis of RC filter circuit, further
Improve the reliability of overcurrent protection route.So the present invention effectively overcomes various shortcoming in the prior art and has height and produce
Industry utility value.
The above-described embodiments merely illustrate the principles and effects of the present invention, and is not intended to limit the present invention.It is any ripe
The personage for knowing this technology all without departing from the spirit and scope of the present invention, carries out modifications and changes to above-described embodiment.Cause
This, institute is complete without departing from the spirit and technical ideas disclosed in the present invention by those of ordinary skill in the art such as
At all equivalent modifications or change, should be covered by the claims of the present invention.
Claims (10)
1. a kind of current foldback circuit of pfc converter, which is characterized in that the current foldback circuit of the pfc converter is at least
Include:
PFC main circuit, sampling module, over-current detection module, PFC control module and drive module；
The sampling module is connected with the power switch tube of the PFC main circuit, and detection flows through the electric current of the power switch tube；
The over-current detection module is connected to the output end of the sampling module, defeated based on the electric current for flowing through the power switch tube
Corresponding out to cross flow control signals, the effective status for crossing flow control signals continues setting time；
The PFC control module is connected to the output end of the PFC main circuit, the output signal control based on the PFC main circuit
Make the duty ratio of the pulse-modulated signal of the power switch tube；
The drive module is connected to the output end of the over-current detection module and the PFC control module, is based on the overcurrent
Control signal and the pulse-modulated signal control the on-off of the power switch tube.
2. the current foldback circuit of pfc converter according to claim 1, it is characterised in that: the over-current detection module
Including comparing unit and holding unit；The input terminal of the comparing unit is separately connected the output end and overcurrent of the sampling module
Threshold value is protected, the output signal of the sampling module is compared with the overcurrent protection threshold value, and export comparison result；Institute
The output end that holding unit is connected to the comparing unit is stated, when the effective status for crossing flow control signals is kept setting
Between.
3. the current foldback circuit of pfc converter according to claim 2, it is characterised in that: the holding unit includes D
Trigger；The input end of clock of the d type flip flop connects the output end of the comparing unit, and data input pin connects power supply, multiple
Position end connects the output end of the PFC control module, and reversed-phase output output is described to cross flow control signals.
4. the current foldback circuit of pfc converter according to claim 2, it is characterised in that: the holding unit includes
RC filter, the input terminal of the RC filter connect the output end of the comparing unit, and the output end of the RC filter is defeated
It is described out to cross flow control signals.
5. the current foldback circuit of pfc converter according to claim 4, it is characterised in that: the RC filter includes
First resistor, first capacitor and switching tube；One end of the first resistor connects power supply, after the other end connects the first capacitor
Ground connection, the first resistor connect the drive module with the connecting node of the first capacitor, export the flow control of crossing and believe
Number；The paralleled power switches connect the defeated of the comparing unit in the both ends of the first capacitor, the control terminal of the switching tube
Outlet.
6. the current foldback circuit of pfc converter according to claim 4, it is characterised in that: the holding unit also wraps
Wave detector is included, the wave detector is connected between the output end of the RC filter and the input terminal of the PFC control module, institute
It states wave detector and overcurrent protection mode control signal is generated based on the output signal of the RC filter, to control the PFC control
Module enters overcurrent protection mode.
7. the current foldback circuit of pfc converter according to claim 6, it is characterised in that: the wave detector includes steady
Press diode, second resistance and the second capacitor；The cathode connection of the zener diode is described to cross flow control signals, anode connection
It is grounded after the second resistance, the connecting node of the zener diode and the second resistance exports the PFC control module
Mode control signal；Second capacitor is parallel to the both ends of the second resistance.
8. the current foldback circuit of pfc converter described in any one according to claim 1~7, it is characterised in that: described
PFC main circuit includes reactor, power switch tube and booster diode；
One end of the reactor connects the input anode of the power inverter, and the other end is connecting the booster diode just
Pole, the output end of the cathode connection DC bus-bar voltage of the booster diode；
The power switch tube is connected to the anode of the booster diode and with reference between ground, and control terminal connects the driving mould
Block.
9. a kind of over-current protection method of pfc converter, which is characterized in that the over-current protection method of the pfc converter is at least
Include:
Overcurrent protection threshold value is set, and acquisition flows through the electric current of the power switch tube of PFC main circuit, and by the power switch tube
Current sampling signal is compared with the overcurrent protection threshold value；
When the current sampling signal of the power switch tube is greater than the overcurrent protection threshold value, crosses flow control signals and come into force and hold
Continuous setting time；When the mistake flow control signals come into force, the driving signal of the power switch tube is blocked；
When the current sampling signal of the power switch tube is less than the overcurrent protection threshold value, and the flow control Signal Fail excessively
When, the driving signal of the power switch tube is restored.
10. the over-current protection method of pfc converter according to claim 9, it is characterised in that: the pfc converter
Over-current protection method further include:
When the flow control signals of crossing continuously come into force several times and when each active states continue setting time, PFC control module into
Enter overcurrent protection mode.
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| CN201910335184.XA CN109921386A (en) | 2019-04-24 | 2019-04-24 | The current foldback circuit and method of pfc converter |
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|---|---|---|---|
| CN201910335184.XA CN109921386A (en) | 2019-04-24 | 2019-04-24 | The current foldback circuit and method of pfc converter |
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| CN111181127A (en) * | 2020-02-13 | 2020-05-19 | 海信（山东）空调有限公司 | Circuit control device and method |
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| CN114512961A (en) * | 2022-02-22 | 2022-05-17 | 北京控制工程研究所 | Self-adaptive protection design method suitable for deep space sampling high-power direct current motor limit condition |
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| CN114006354A (en) * | 2021-09-16 | 2022-02-01 | 北京无线电测量研究所 | Overcurrent protection circuit |
| CN114062771B (en) * | 2022-01-14 | 2022-04-12 | 天宜微电子(北京)有限公司 | Overcurrent detection circuit, overcurrent detection method and direct current conversion system |
| CN114062771A (en) * | 2022-01-14 | 2022-02-18 | 天宜微电子(北京)有限公司 | Overcurrent detection circuit, overcurrent detection method and direct current conversion system |
| CN114512961A (en) * | 2022-02-22 | 2022-05-17 | 北京控制工程研究所 | Self-adaptive protection design method suitable for deep space sampling high-power direct current motor limit condition |
| CN114512961B (en) * | 2022-02-22 | 2023-11-10 | 北京控制工程研究所 | Limit working condition self-adaptive protection design method suitable for deep space sampling high-power direct current motor |
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| CN116799746A (en) * | 2023-08-16 | 2023-09-22 | 天合光能股份有限公司 | Protection circuit, load protection method and protection system |
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| CN117317977B (en) * | 2023-11-02 | 2024-03-15 | 深圳市德兰明海新能源股份有限公司 | Switching tube driving protection circuit and energy storage power supply |
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