CN106655823B - Anti-magnetic interference switching power supply and control circuit and control method thereof - Google Patents
Anti-magnetic interference switching power supply and control circuit and control method thereof Download PDFInfo
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- CN106655823B CN106655823B CN201610953347.7A CN201610953347A CN106655823B CN 106655823 B CN106655823 B CN 106655823B CN 201610953347 A CN201610953347 A CN 201610953347A CN 106655823 B CN106655823 B CN 106655823B
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
Abstract
Disclosed are a switching power supply, and a control circuit and a control method thereof. The control circuit comprises an error amplifying unit for providing an error amplifying signal according to the output voltage of the switching power supply, a magnetic field detecting unit for judging whether the switching power supply is influenced by an external magnetic field and providing a magnetic field detection signal, a frequency control unit for providing a clock signal according to the magnetic field detection signal, and a switching control unit for providing a switching control signal to control a main power switch in the switching power supply, wherein the switching control unit controls the duty ratio of the main power switch in response to the error amplifying signal and controls the switching frequency of the main power switch in response to the clock signal. Compared with the prior art, the controllable switching frequency is realized, meanwhile, the interference of an external magnetic field to the switching power supply can be eliminated or weakened, and the controllable switching frequency has a simpler structure and lower cost.
Description
Technical field
The embodiment of the present invention is related to a kind of electronic circuit, more specifically more particularly to a kind of Switching Power Supply.
Background technique
Switching Power Supply has many advantages, such as that faster transient response, lower loss have been widely used in each field due to it
In.However, the problem of there may be strong external magnetic field interference will be faced when being applied to the fields such as ammeter.It is a kind of existing
Solution is, increases mechanical masking shell, and to shield interference of the strong external magnetic field to Switching Power Supply, the shortcomings that such method is
Increase cost and volume.Another existing solution is, when designing the magnetic element in Switching Power Supply, such as design electricity
When sense or transformer, there are very big surplus, such method is very huge by the magnetics volume that will lead in Switching Power Supply
Greatly, while cost is also increased.
Summary of the invention
In order to solve the above technical problems, the present invention provides a kind of Switching Power Supply and its control circuit and control method.
A kind of control circuit for Switching Power Supply according to an embodiment of the present invention, the Switching Power Supply include magnetic member
Part, the master power switch for being coupled to magnetic element, receive input voltage input port and provide output voltage output end
Mouthful, the control circuit includes: error amplifying unit, has first input end, the second input terminal and output end, wherein first is defeated
Enter end and receive reference signal, the second input terminal receives the voltage feedback signal for representing output voltage, the error amplifying unit root
According to the difference between reference signal and voltage feedback signal, error amplification signal is provided in output end；Magnetic field detection unit, has
Whether output end, the magnetic field detection unit judges Switching Power Supply are influenced by external magnetic field, and provide magnetic in its output end
Field detecting signal；Frequency control unit has first input end, the second input terminal, third input terminal and output end, wherein first
Input terminal is coupled to the output end of magnetic field detection unit to receive magnetic field detection signal, and the second input terminal receives set of frequency electricity
Pressure, third input terminal receive frequency adjust voltage, the frequency control unit according to magnetic field detection signal, set of frequency voltage,
And frequency adjustment voltage provides clock signal in its output end, when magnetic field detection direction switch signal power supply is not affected by external magnetic
When the influence of field, frequency control unit is equal to a predetermined frequency value according to the frequency of set of frequency voltage-control clock signal, when
When magnetic field detection direction switch signal power supply receives the influence of external magnetic field, frequency control unit according to set of frequency voltage and
The frequency that frequency adjusts voltage-control clock signal is equal to N times of the predetermined frequency value, and N is the integer greater than 1；And switch
Control unit has first input end, the second input terminal and output end, and wherein first input end is coupled to error amplifying unit
Output end, the second input terminal are coupled to the output end of frequency control unit to receive clock signal, and the switch control unit exists
Its output end provides switch control signal to control the conducting and shutdown of master power switch, and wherein switch control unit is in response to accidentally
The duty ratio of poor amplified signal control master power switch, in response to the switching frequency of clock signal control master power switch.
A kind of Switching Power Supply according to an embodiment of the present invention, comprising: transformer has armature winding and secondary windings,
Middle armature winding receives input voltage；Master power switch is coupled to armature winding；Rectification circuit is coupled to secondary windings and mentions
For output voltage；Feed circuit provides the voltage feedback signal for representing output voltage；And control circuit, receive Voltage Feedback
Signal, and switch control signal is provided according to voltage feedback signal to control the conducting and shutdown of master power switch, the control
Circuit controls the duty ratio of master power switch in response to voltage feedback signal, the control circuit according to Switching Power Supply whether by
To the switching frequency of the influence control master power switch of external magnetic field, wherein when Switching Power Supply is not affected by the influence of external magnetic field
When, the switching frequency for controlling master power switch is equal to predetermined frequency value, and when Switching Power Supply is influenced by external magnetic field,
The switching frequency for controlling master power switch is equal to N times of the predetermined frequency value, and N is the integer greater than 1.
A kind of control method for Switching Power Supply according to an embodiment of the present invention, the Switching Power Supply include magnetic member
Part, the master power switch for being coupled to magnetic element, receive input voltage input port and provide output voltage output end
Mouthful, the control method includes: to provide voltage feedback signal according to output voltage；According to reference signal and voltage feedback signal it
Between difference provide error amplification signal；According to error amplification signal, the duty ratio of master power switch is controlled；And judgement switch
Whether power supply is influenced by external magnetic field；Wherein when Switching Power Supply is not affected by the influence of external magnetic field, Switching Power Supply is in
Normal mode of operation, control switch frequency are equal to first frequency preset value；And when Switching Power Supply is influenced by external magnetic field,
Switching Power Supply enters diamagnetic mode, and control switch frequency is equal to second frequency preset value, and wherein second frequency preset value is greater than the
One predetermined frequency value.
Switching Power Supply according to an embodiment of the present invention can be eliminated or weaken outer while realizing that switching frequency is controllable
Interference of the portion magnetic field to Switching Power Supply has better simply structure and lower cost.
Detailed description of the invention
It in order to better understand the present invention, will the present invention will be described in detail according to the following drawings:
Fig. 1 shows the circuit block diagram of Switching Power Supply 100 according to an embodiment of the invention；
Fig. 2 shows the circuit block diagrams of Switching Power Supply 200 according to an embodiment of the invention；
Fig. 3 shows Switching Power Supply 200 shown in Fig. 2 according to an embodiment of the invention according to error amplification signal COMP tune
The schematic diagram of whole switching frequency Fs；
Fig. 4 shows the circuit structure diagram of magnetic field detection unit 32 according to an embodiment of the invention；
Fig. 5 shows Switching Power Supply 200 shown in Fig. 2 according to an embodiment of the invention according to the oblique of current detection signal CS
The schematic diagram of rate Rcs adjustment switching frequency Fs；
Fig. 6 shows the circuit structure diagram of magnetic field detection unit 32 according to another embodiment of the present invention；
Fig. 7 shows the circuit structure diagram of frequency control unit 33 according to an embodiment of the invention；
Fig. 8 shows the control method flow chart according to an embodiment of the invention for Switching Power Supply.
Specific embodiment
Specific embodiments of the present invention are described more fully below, it should be noted that the embodiments described herein is served only for illustrating
Illustrate, is not intended to restrict the invention.In the following description, in order to provide a thorough understanding of the present invention, a large amount of spies are elaborated
Determine details.It will be apparent, however, to one skilled in the art that: this hair need not be carried out using these specific details
It is bright.In other instances, in order to avoid obscuring the present invention, well known circuit, material or method are not specifically described.
Throughout the specification, meaning is referred to " one embodiment ", " embodiment ", " example " or " example "
: a particular feature, structure, or characteristic described in conjunction with this embodiment or example is comprised at least one embodiment of the invention.
Therefore, the phrase " in one embodiment ", " in embodiment ", " example " occurred in each place of the whole instruction
Or " example " is not necessarily all referring to the same embodiment or example.Furthermore, it is possible in any suitable combination and or sub-portfolio will be specific
Feature, structure or characteristic combine in one or more embodiment or examples.In addition, those of ordinary skill in the art should manage
Solution, attached drawing is provided to the purpose of explanation provided herein, and attached drawing is not necessarily drawn to scale.It should be appreciated that working as
When claiming element " being couple to " or " being connected to " another element, it, which can be, directly couples or is couple to another element or can deposit
In intermediary element.On the contrary, intermediary element is not present when claiming element " being directly coupled to " or " being directly connected to " another element.
Identical appended drawing reference indicates identical element.Term "and/or" used herein includes the item that one or more correlations are listed
Any and all combinations of purpose.
For the problems raised in the background art, the embodiment of the present invention proposes one kind and can be opened according to external magnetic field adjustment
Close the Switching Power Supply of frequency.When Switching Power Supply is not affected by the influence of external magnetic field, the Switching Power Supply is worked normally, switch frequency
Rate is equal to predetermined frequency value；When Switching Power Supply is influenced by external magnetic field, the Switching Power Supply enters diamagnetic mode, switch
Frequency is equal to N times of predetermined frequency value, and N is the positive integer greater than 1.
Fig. 1 shows the circuit block diagram of Switching Power Supply 100 according to an embodiment of the invention.Switching Power Supply 100 includes connecing
Receive input port, the output port that output voltage Vo is provided including the magnetic element 11 and master power switch 12 of input voltage vin
Power circuit 10, feed circuit 20 and control circuit 30, wherein master power switch 12 is coupled to magnetic element 11.Feedback
20 sampling and outputting voltage Vo of circuit, and the voltage feedback signal VFB for representing output voltage Vo is provided.Control circuit 30 receives voltage
Feedback signal VFB, and switch control signal Vg is provided to control the conducting and shutdown of master power switch 12.30 basis of control circuit
The duty ratio of voltage feedback signal VFB control master power switch 12.Skilled person will appreciate that the duty of master power switch 12
Than the ratio between conducting duration and the switch periods for representing master power switch 12.Whether control circuit 30 judges Switching Power Supply by outer
The influence in portion magnetic field.When Switching Power Supply 100 is not affected by the influence of external magnetic field, Switching Power Supply 100 is in normal mode of operation,
The switching frequency Fs that control circuit 30 controls master power switch 12 is equal to predetermined frequency value Fset1；Otherwise when Switching Power Supply 100 by
To external magnetic field influence when, Switching Power Supply 100 enter diamagnetic mode, control circuit 30 control master power switch 12 switch frequency
Rate Fs is equal to predetermined frequency value Fset2, and predetermined frequency value Fset1 of the predetermined frequency value Fset2 for example equal to N times, wherein N is big
In 1 positive integer.The switching frequency Fs of master power switch 12 i.e. the switching frequency of Switching Power Supply 100.Predetermined frequency value
Fset1, Fset2 are constant, such as Fset1 is equal to 200kHz, and Fset2 is equal to 400kHz.
In one embodiment, control circuit 30 includes error amplifying unit 31, magnetic field detection unit 32, frequency control list
Member 33 and switch control unit 34.Error amplifying unit 31 has first input end, the second input terminal and output end, wherein
First input end receives reference signal Vref, and the second input terminal receives voltage feedback signal VFB, and error amplifying unit 31 is according to ginseng
The difference (Vref-VFB) for examining signal Vref and voltage feedback signal VFB provides error amplification signal COMP in its output end.Magnetic
Field detecting unit 32 judge Switching Power Supply 100 whether the influence by external magnetic field, and its output end provide magnetic field detection letter
Number Mag.Frequency control unit 33 has first input end, the second input terminal, third input terminal and output end, wherein the first input
End is coupled to the output end of magnetic field detection unit 32 to receive magnetic field detection signal Mag, and the second input terminal receives set of frequency electricity
Vset is pressed, third input terminal receives frequency and adjusts voltage Vsub, and output end is according to magnetic field detection signal Mag, set of frequency voltage
Vset and frequency adjustment voltage Vsub export clock signal Clk.When magnetic field detection signal Mag instruction Switching Power Supply 100 is not affected by
When the influence of external magnetic field, frequency etc. of the frequency control unit 33 in response to set of frequency voltage Vset control clock signal Clk
In predetermined frequency value Fset1；When magnetic field detection signal Mag instruction Switching Power Supply 100 is influenced by external magnetic field, frequency control
Unit 33 processed is equal to frequency in response to the frequency of set of frequency voltage Vset and frequency adjustment voltage Vsub control clock signal Clk
Preset value Fset2.Switch control unit 34 has first input end, the second input terminal and output end, wherein first input end coupling
The output end of error amplifying unit 31 is connected to receive error amplification signal COMP, the second input terminal is coupled to frequency control unit
To receive clock signal Clk, switch control unit 34 is based on error amplification signal COMP and clock signal Clk and exists 33 output end
Its output end provides switch control signal Vg to control the conducting and shutdown of master power switch 12.Wherein, switch control unit 34
Based on the duty ratio of error amplification signal COMP control master power switch 12, master power switch 12 is controlled based on clock signal Clk
Switching frequency Fs.
In one embodiment, magnetic element 11 includes inductance or transformer.
In one embodiment, master power switch 12 is controllable semiconductor switch device, such as metal-oxide semiconductor (MOS)
Field effect transistor (MOSFET), lateral diffusion metal oxide semiconductor (LDMOS), insulated gate bipolar transistor (IGBT).
Switching Power Supply 100 is guaranteeing controllable same of switching frequency Fs by adjusting the switching frequency Fs of master power switch 12
When, weaken or eliminate influence of the external magnetic field to Switching Power Supply 100, ensure that Switching Power Supply 100 under strong magnetic field circumstance
It can work normally.
Fig. 2 shows the circuit block diagrams of Switching Power Supply 200 according to an embodiment of the invention.Embodiment shown in Fig. 2
By taking reverse exciting topological as an example, however skilled person will appreciate that, other suitable circuit topologies can be used for the present invention, example
Such as LLC resonance circuit, booster circuit.Switching Power Supply 200 include the magnetic element being made of transformer T1, master power switch S1,
Rectification circuit 21, by optic coupling element 22 and resistance the R1 feed circuit formed and control circuit 30.Transformer T1, which has, to be received
The armature winding of input voltage vin and by rectification circuit 21 provide output voltage Vo secondary windings, master power switch S1 coupling
It is connected to armature winding.One end of rectification circuit 21 is coupled to the secondary windings of transformer T1, and the other end of rectification circuit 21 provides
Output voltage Vo.In the embodiment shown in Figure 2, rectification circuit 21 includes rectifier diode D1.Switching Power Supply 200 further includes coupling
The input capacitance C1 between input voltage vin and primary side reference ground GND1 is met, and is coupled in output voltage Vo and secondary side ginseng
Examine the output capacitance C2 between ground GND2.In one embodiment, Switching Power Supply 200 further includes that current detection circuit (does not show
Out), for detecting the electric current Is for flowing through master power switch S1, and the current detection signal CS for representing electric current Is is provided.In Fig. 2 institute
In the embodiment shown, magnetic field detection unit 32 receives error amplification signal COMP or current detection signal CS, and is put according to error
Big signal COMP or current detection signal CS judge Switching Power Supply 200 whether the influence by external magnetic field, and magnetic field is provided and is examined
Survey signal Mag.
In the embodiment shown in Figure 2, error amplifying unit 31 includes error amplifier EA and its compensation network 23.Error
The non-inverting input terminal of amplifier EA receives reference signal Vref, and inverting input terminal receives voltage feedback signal VFB, output end according to
The difference of reference signal Vref and voltage feedback signal VFB provide error amplification signal COMP.Compensation network 23 for example can wrap
Include lead compensation network, lag compensation network or lead-lag compensation network.In the embodiment shown in Figure 2, compensation network
23 include resistance Rx, the capacitor Cx being coupled in series between the inverting input terminal and output end of error amplifier EA.This field skill
Art personnel are it is found that compensation network 23 is not limited to specific embodiment shown in Fig. 2.
In one embodiment, control circuit 30 further includes current control unit 35, has first input end, the second input
End and output end, wherein first input end receives error amplification signal COMP, and the second input terminal receives current detection signal CS, defeated
Outlet generates current controling signal VI according to the comparison result of error amplification signal COMP and current detection signal CS.Switch control
Unit 34 adjusts the duty ratio of master power switch S1 according to current controling signal VI.In the embodiment shown in Figure 2, current control
Unit 35 includes comparator CMP.
In the embodiment shown in Figure 2, switch control unit 34 includes RS trigger circuit, and set end S is coupled to frequency
For the output end of control unit 33 to receive clock signal Clk, reset terminal R is coupled to the output end of current control unit 35 to connect
Current controling signal VI is received, output end provides switch control signal Vg according to clock signal Clk and current controling signal VI.?
In one embodiment, when the periodic setting switch of clock signal Clk controls conducting of the signal Vg to control master power switch S1
It carves, current controling signal VI is controlled according to the comparison result reset switch of current sampling signal CS and error amplification signal COMP to be believed
Number Vg, to control the shutdown moment of master power switch S1.In another embodiment, the reset terminal of RS trigger circuit 34 is coupled to
The output end of error amplifying unit 31 is to receive error amplification signal COMP, and according to error amplification signal COMP reset switch control
Signal Vg processed, to control the shutdown moment of master power switch S1.
Fig. 3 shows Switching Power Supply 200 shown in Fig. 2 according to an embodiment of the invention according to error amplification signal COMP tune
The schematic diagram of whole switching frequency Fs.Schematic diagram abscissa shown in Fig. 3 is error amplification signal COMP, and ordinate is switching frequency
Fs.When Switching Power Supply 200 is not affected by the influence of external magnetic field, the switching frequency Fs of master power switch S1 is equal to predetermined frequency value
Fset1.As shown in figure 3, judging Switching Power Supply 200 by external magnetic field when error amplification signal COMP is greater than threshold value Vth1
Influence, magnetic field detection signal Mag=1, Switching Power Supply 200 enter diamagnetic mode, control master power switch S1 switching frequency
Fs is equal to predetermined frequency value Fset2；When error amplification signal COMP is less than threshold value Vth2, judge external magnetic field to Switching Power Supply
200 influence releasing or Switching Power Supply 200 are not affected by the influence of external magnetic field, magnetic field detection signal Mag=0, Switching Power Supply 200
Diamagnetic mode is exited, the switching frequency Fs of control master power switch S1 is equal to predetermined frequency value Fset1.Threshold value Vth1 is greater than threshold value
Vth2。
Fig. 4 shows the circuit structure diagram of magnetic field detection unit 32 according to an embodiment of the invention.Reality shown in Fig. 4
It applies in example, magnetic field detection unit 32 includes stagnant ring comparison circuit 41, including first input end, the second input terminal, third input terminal
And output end, wherein first input end receives error amplification signal COMP, and the second input terminal receives threshold value Vth1, third input terminal
Threshold value Vth2 is received, output end provides magnetic field detection according to error amplification signal COMP and the comparison result of threshold value Vth1, Vth2
Signal Mag.
Fig. 5 shows Switching Power Supply 200 shown in Fig. 2 according to an embodiment of the invention according to the oblique of current detection signal CS
The schematic diagram of rate Rcs adjustment switching frequency Fs.Schematic diagram abscissa shown in fig. 5 is the slope Rcs of current detection signal CS, is indulged
Coordinate is switching frequency Fs.When Switching Power Supply 200 is not affected by the influence of external magnetic field, the switching frequency Fs of master power switch S1
Equal to predetermined frequency value Fset1.As shown in figure 5, when the slope Rcs of current detection signal CS is greater than threshold k 1*Vin, judgement
Switching Power Supply 200 is influenced by external magnetic field, magnetic field detection signal Mag=1, and Switching Power Supply 200 enters diamagnetic mode, control
The switching frequency Fs of master power switch S1 is equal to predetermined frequency value Fset2；When the slope Rcs of current detection signal CS is less than threshold value
When K2*Vin, judge that influence releasing or Switching Power Supply 200 of the external magnetic field to Switching Power Supply 200 are not affected by the shadow of external magnetic field
It rings, magnetic field detection signal Mag=0, Switching Power Supply 200 exits diamagnetic mode, controls the switching frequency Fs etc. of master power switch S1
In predetermined frequency value Fset1.Wherein COEFFICIENT K 1, K2 are greater than zero, and K1 is greater than K2.
Fig. 6 shows the circuit structure diagram of magnetic field detection unit 32 according to another embodiment of the present invention.Reality shown in fig. 6
It applies in example, magnetic field detection unit 32 includes slope detecting circuit 61, electric voltage feed forward circuit 62 and comparison circuit 63.Slope inspection
Slowdown monitoring circuit 61 receives current detection signal CS, and provides the slope Rcs of current detection signal CS according to current detection signal CS.?
In one embodiment, slope detecting circuit 61 includes capacitor 64 and resistance 65.The first end of capacitor 64 receives current detection signal
The second end of CS, capacitor 64 provide the slope Rcs of current detection signal CS.Resistance 65 is coupled in the second end and primary side of capacitor 64
With reference between ground.Electric voltage feed forward circuit 62 receives input voltage vin, and provides threshold k 1*Vin, K2* according to input voltage vin
Vin.In one embodiment, electric voltage feed forward circuit 62 includes resistance 66, resistance 67, resistance 68.66~68 coupled in series of resistance
Between input voltage vin and primary side reference ground, resistance pressure-dividing network is formed, wherein the common end of resistance 66 and resistance 67 provides
The common end of threshold k 1*Vin, resistance 67 and resistance 68 provides threshold k 2*Vin.Comparison circuit 63 includes first input end, second
Input terminal, third input terminal and output end, wherein first input end receives the slope Rcs of current detection signal CS, the second input
End receives threshold k 1*Vin, and third input terminal receives threshold k 2*Vin, output end according to the slope Rcs of current detection signal CS and
The comparison result of threshold k 1*Vin, K2*Vin provides magnetic field detection signal Mag.In master power switch S1 conducting, if electric current is examined
The slope Rcs for surveying signal is greater than threshold k 1*Vin, judges influence of the Switching Power Supply 200 by external magnetic field, magnetic field detection signal
Mag becomes first state, such as Mag=" 1 "；In master power switch S1 conducting, if the slope Rcs of current detection signal is less than
Threshold k 2*Vin judges that Switching Power Supply 200 is no longer influenced by the influence of external magnetic field, and magnetic field detection signal Mag becomes the second state,
Such as Mag=" 0 "；And in master power switch S1 shutdown, magnetic field detection signal Mag remains unchanged.In one embodiment,
Comparison circuit 63 includes comparator 631, comparator 632, gate circuit 633, gate circuit 634 and rest-set flip-flop 635.Comparator
631 non-inverting input terminal receives the slope Rcs of current detection signal CS, and the inverting input terminal of comparator 631 receives threshold k 1*
Vin.The non-inverting input terminal of comparator 632 receives the slope Rcs of current detection signal CS, the anti-phase input termination of comparator 632
Receive threshold k 2*Vin.Gate circuit 633 has first input end, the second input terminal and output end, and wherein first input end is coupled to
The output end of comparator 631, the second input terminal receive switch control signal Vg.Gate circuit 634 has first input end, second defeated
Enter end and output end, wherein first input end is coupled to the output end of comparator 632, and the second input terminal receives switch control signal
Vg.Rest-set flip-flop 635 has set end S, reset terminal R and output end Q, and wherein set end S is coupled to the output of gate circuit 633
End, reset terminal R are coupled to the output end of gate circuit 634, and output end Q provides magnetic field detection signal Mag.As switch control signal Vg
Control master power switch S1 conducting, and the slope Rcs of current detection signal be greater than threshold k 1*Vin when, 635 set of rest-set flip-flop
Export the magnetic field detection signal Mag of high level；When switch control signal Vg control master power switch S1 conducting, and current detecting is believed
Number slope Rc when being less than threshold k 2*Vin, rest-set flip-flop 635, which resets, exports low level magnetic field detection signal Mag；Work as switch
When controlling signal Vg control master power switch S1 shutdown, magnetic field detection signal Mag remains unchanged.
Fig. 7 shows the circuit structure diagram of frequency control unit 33 according to an embodiment of the invention.Implementation shown in Fig. 7
In example, frequency control unit 33 is including generating circuit from reference voltage 71, comparison circuit 75 and by capacitor 72, current source 73, switch
74 and one-shot circuit 76 form sawtooth wave generative circuit.Generating circuit from reference voltage 71 receives set of frequency voltage
Vset, frequency adjust voltage Vsub, magnetic field detection signal Mag, and adjust voltage Vsub according to set of frequency voltage Vset, frequency
Reference voltage Vfr is provided with magnetic field detection signal Mag.When judging that Switching Power Supply 200 is not affected by the influence of external magnetic field, magnetic field
Detection signal Mag is the second state, such as Mag=0, reference voltage Vfr are equal to set of frequency voltage Vset；When judgement switch electricity
When source 200 is influenced by external magnetic field, magnetic field detection signal Mag is first state, such as Mag=1, reference voltage Vfr etc.
In the difference Vset-Vsub of set of frequency voltage Vset and frequency adjustment voltage Vsub.In one embodiment, reference voltage generates
Circuit 71 includes computing circuit 77 and switch 78.Computing circuit 77 includes first input end, the second input terminal and output end, wherein
First input end reception set of frequency voltage Vset, the second input terminal are coupled to the first end of switch 78, and output end provides reference
Voltage Vfr.The second end of switch 78 receives frequency and adjusts voltage Vsub, and the control terminal of switch 78 receives magnetic field detection signal Mag,
Switch 78 is connected and turns off under the control of magnetic field detection signal Mag.When magnetic field detection signal Mag indicates Switching Power Supply 200 not
When being influenced by external magnetic field, switch 78 is turned off, and the second input terminal of computing circuit 77 is zero, and reference voltage Vfr is equal to frequency
Voltage Vset is arranged in rate.When magnetic field detection direction switch signal power supply 200 is influenced by external magnetic field, switch 78 is connected,
Reference voltage Vfr is equal to the difference Vset-Vsub of set of frequency voltage Vset and frequency adjustment voltage Vsub.Those skilled in the art
It is found that generating circuit from reference voltage 71 is not limited to specific embodiment shown in Fig. 7.Capacitor 72, which has, provides sawtooth voltage Vsaw
First end and be coupled to the second end of primary side reference ground, 73 coupled in parallel of current source is closed at the both ends of capacitor 72 in switch 74
It charges when disconnected to capacitor 72, so that sawtooth voltage Vsaw increases to reference voltage Vfr.74 coupled in parallel of switch is in capacitor 72
Both ends, one-shot circuit 76 provide single pulse signal Pul according to clock signal Clk with control switch 74.Work as sawtooth voltage
When Vsaw is greater than reference voltage Vfr, clock signal Clk overturning, such as become high level, one-shot circuit 76, which provides, remains certain
The single pulse signal Pul of time high level is discharged with the conducting of control switch 74, capacitor 72 by switch 74.Single pulse signal Pul
Such as maintain 2us high level.Comparison circuit 75 has first input end, the second input terminal and output end, wherein first input end
Reference voltage Vfr is received, the second input terminal receives sawtooth voltage Vsaw, and output end is according to reference voltage Vfr and sawtooth wave electricity
The result that pressure Vsaw compares provides clock signal Clk.
Fig. 8 shows the control method flow chart according to an embodiment of the invention for Switching Power Supply.The Switching Power Supply
Including magnetic element, the master power switch that is coupled to magnetic element, the input port for receiving input voltage and provide output electricity
The output port of pressure.The control method includes step S11~S16.
In step S11, voltage feedback signal is provided according to output voltage.
In step S12, error amplification signal is provided according to the difference between reference signal and voltage feedback signal.
The duty ratio of master power switch is controlled according to error amplification signal in step S13.
In step S14, judge Switching Power Supply whether the influence by external magnetic field.If Switching Power Supply is not affected by external magnetic field
Influence, then enter step S15, Switching Power Supply is in normal mode of operation, and control switch frequency is equal to first frequency preset value.
If Switching Power Supply is influenced by external magnetic field, S16 is entered step, Switching Power Supply enters diamagnetic mode, control switch frequency
Equal to second frequency preset value, wherein second frequency preset value is greater than first frequency preset value.In one embodiment, the second frequency
Rate preset value is equal to N times of first frequency preset value, and N is the integer greater than 1.
In one embodiment, when error amplification signal is greater than first threshold, judge Switching Power Supply by external magnetic field
Influence；When error amplification signal is less than second threshold, judge that Switching Power Supply is not affected by the influence of external magnetic field.
In one embodiment, control method further include: the electric current of master power switch is flowed through in detection, provides current detecting
Signal.When the slope of current detection signal is greater than third threshold value, influence of the Switching Power Supply by external magnetic field is judged；Work as electric current
When detecting the slope of signal less than four threshold values, judge that Switching Power Supply is not affected by the influence of external magnetic field.Wherein third threshold value is big
In the 4th threshold value, and third threshold value and the 4th threshold value equidirectional variation with the variation of input voltage, such as with input electricity
The increase of pressure and increase, reduce with the reduction of input voltage.
In one embodiment, the control method further include: when Switching Power Supply is not affected by the influence of external magnetic field, according to
Set of frequency voltage provides reference voltage；When Switching Power Supply is influenced by external magnetic field, according to set of frequency voltage and frequency
Rate adjusts difference in voltage and provides reference voltage；By control to capacitor charge and discharge, provided at the both ends of capacitor periodically variable
Sawtooth voltage；According to reference voltage compare with sawtooth voltage as a result, provide clock signal to control master power switch
Switching frequency.Wherein when sawtooth voltage is greater than reference voltage, clock signal overturning, capacitor discharges, and master power switch is led
It is logical.
Although exemplary embodiment describes the present invention with reference to several, it is to be understood that, term used is explanation and shows
Example property, term and not restrictive.The spirit or reality that can be embodied in a variety of forms due to the present invention without departing from invention
Matter, it should therefore be appreciated that above-described embodiment is not limited to any of the foregoing details, and the spirit defined by appended claims
It all should be accompanying power with the whole change and modification widely explained, therefore fallen into claim or its equivalent scope in range
Benefit requires to be covered.
Claims (11)
1. a kind of control circuit for Switching Power Supply, the Switching Power Supply includes magnetic element, the master for being coupled to magnetic element
The output port of power switch, the input port for receiving input voltage and offer output voltage, the control circuit include:
Error amplifying unit has first input end, the second input terminal and output end, and wherein first input end is received with reference to letter
Number, the second input terminal receives the voltage feedback signal for representing output voltage, and the error amplifying unit is according to reference signal and electricity
The difference between feedback signal is pressed, provides error amplification signal in output end；
Magnetic field detection unit, have output end, the magnetic field detection unit judges Switching Power Supply whether the shadow by external magnetic field
It rings, and provides magnetic field detection signal in its output end；
Frequency control unit has first input end, the second input terminal, third input terminal and output end, wherein first input end
The output end of magnetic field detection unit is coupled to receive magnetic field detection signal, the second input terminal receives set of frequency voltage, third
Input terminal receives frequency and adjusts voltage, and the frequency control unit is according to magnetic field detection signal, set of frequency voltage and frequency
It adjusts voltage and provides clock signal in its output end, when magnetic field detection direction switch signal power supply is not affected by the influence of external magnetic field
When, frequency control unit is equal to a predetermined frequency value according to the frequency of set of frequency voltage-control clock signal, works as magnetic field detection
When direction switch signal power supply receives the influence of external magnetic field, frequency control unit is adjusted according to set of frequency voltage and frequency
The frequency of voltage-control clock signal is equal to N times of the predetermined frequency value, and N is the integer greater than 1；And
Switch control unit has first input end, the second input terminal and output end, and wherein first input end is coupled to error and puts
The output end of big unit, the second input terminal are coupled to the output end of frequency control unit to receive clock signal, the switch control
Unit processed controls the conducting and shutdown of master power switch in its output end offer switch control signal, wherein switch control unit
In response to the duty ratio of error amplification signal control master power switch, in response to the switch frequency of clock signal control master power switch
Rate.
2. control circuit as described in claim 1, wherein magnetic field detection unit further includes input terminal, the input terminal, which receives, to be missed
Poor amplified signal, magnetic field detection unit according to error amplification signal judge Switching Power Supply whether the influence by external magnetic field,
In when error amplification signal is greater than first threshold, judge influence of the Switching Power Supply by external magnetic field, magnetic field detection signal becomes
For first state, and when error amplification signal is less than second threshold, judge that Switching Power Supply is no longer influenced by the shadow of external magnetic field
It rings, magnetic field detection signal becomes the second state, and wherein first threshold is greater than second threshold.
3. control circuit as described in claim 1, wherein magnetic field detection unit further includes input terminal, the input terminal receives generation
Table flows through the current detection signal of the electric current of master power switch, and magnetic field detection unit judges according to the slope of current detection signal
Whether Switching Power Supply is influenced by external magnetic field, wherein judgement is opened when the slope of current detection signal is greater than third threshold value
Powered-down source is influenced by external magnetic field, and magnetic field detection signal becomes first state, and when the slope of current detection signal is small
When four threshold values, judging that Switching Power Supply is no longer influenced by the influence of external magnetic field, magnetic field detection signal becomes the second state, wherein
Third threshold value is greater than the 4th threshold value.
4. control circuit as described in claim 1, wherein magnetic field detection unit further include:
Slope detecting circuit, reception represent the current detection signal for the electric current for flowing through master power switch, the slope detection electricity
Road provides the slope of current detection signal according to current detection signal；
Electric voltage feed forward circuit provides third threshold value and the 4th threshold value according to input voltage, wherein third threshold value and the 4th threshold value with
The variation of input voltage and change, and third threshold value be greater than the 4th threshold value；And
Comparison circuit provides magnetic field detection signal according to the slope of current detection signal, third threshold value and the 4th threshold value,
In when the slope of current detection signal be greater than third threshold value when, judge influence of the Switching Power Supply by external magnetic field, magnetic field detection
Signal becomes first state, and when the slope of current detection signal is less than four threshold values, judges that Switching Power Supply is no longer influenced by
The influence of external magnetic field, magnetic field detection signal become the second state.
5. control circuit as described in claim 1, wherein frequency control unit further include:
Generating circuit from reference voltage receives set of frequency voltage, frequency adjustment voltage and magnetic field detection signal, and is set according to frequency
It sets voltage, frequency adjustment voltage and magnetic field detection signal and reference voltage is provided, wherein when magnetic field detection direction switch signal power supply
When receiving the influence of external magnetic field, reference voltage is equal to set of frequency voltage and frequency adjusts difference in voltage, works as magnetic field detection
When direction switch signal power supply is not affected by the influence of external magnetic field, reference voltage is equal to set of frequency voltage；
Sawtooth wave generative circuit provides periodically variable sawtooth voltage；And
Comparison circuit has first input end, the second input terminal and output end, and wherein first input end receives reference voltage, the
Two input terminals receive sawtooth voltage, and output end, which provides clock according to the result that reference voltage compares with sawtooth voltage, to be believed
Number.
6. a kind of Switching Power Supply, comprising:
Transformer has armature winding and secondary windings, and wherein armature winding receives input voltage；
Master power switch is coupled to armature winding；
Rectification circuit is coupled to secondary windings and provides output voltage；
Feed circuit provides the voltage feedback signal for representing output voltage；And
Control circuit receives voltage feedback signal, and provides switch control signal according to voltage feedback signal to control main power
The conducting and shutdown of switch, the control circuit controls the duty ratio of master power switch in response to voltage feedback signal, described
Control circuit according to Switching Power Supply whether by external magnetic field influenced control master power switch switching frequency, wherein working as switch
When power supply is not affected by the influence of external magnetic field, the switching frequency for controlling master power switch is equal to predetermined frequency value, and when switch
When power supply is influenced by external magnetic field, the switching frequency for controlling master power switch is equal to N times of the predetermined frequency value, and N is
Integer greater than 1.
7. Switching Power Supply as claimed in claim 6, wherein control circuit is as described in any one of Claims 1 to 5.
8. a kind of control method for Switching Power Supply, the Switching Power Supply includes magnetic element, the master for being coupled to magnetic element
The output port of power switch, the input port for receiving input voltage and offer output voltage, the control method include:
Voltage feedback signal is provided according to output voltage；
Error amplification signal is provided according to the difference between reference signal and voltage feedback signal；
According to error amplification signal, the duty ratio of master power switch is controlled；And
Judge Switching Power Supply whether the influence by external magnetic field；Wherein
When Switching Power Supply is not affected by the influence of external magnetic field, Switching Power Supply is in normal mode of operation, control switch frequency etc.
In first frequency preset value；And
When Switching Power Supply is influenced by external magnetic field, Switching Power Supply enters diamagnetic mode, and control switch frequency is equal to the second frequency
Rate preset value, wherein second frequency preset value is greater than first frequency preset value.
9. control method as claimed in claim 8, wherein judging whether Switching Power Supply is influenced to include: by external magnetic field
When error amplification signal is greater than first threshold, judge Switching Power Supply by external magnetic fields；And
When error amplification signal is less than second threshold, judge that Switching Power Supply is not affected by the influence of external magnetic field；Wherein
First threshold is greater than second threshold.
10. control method as claimed in claim 8, wherein judging whether Switching Power Supply is influenced to include: by external magnetic field
The electric current of master power switch is flowed through in detection, provides current detection signal；
When the slope of current detection signal is greater than third threshold value, influence of the Switching Power Supply by external magnetic field is judged；And
When the slope of current detection signal is less than four threshold values, judge that Switching Power Supply is not affected by the influence of external magnetic field；Wherein
Third threshold value is greater than the 4th threshold value, and third threshold value and the 4th threshold value change with the variation of input voltage.
11. control method as claimed in claim 8, further includes:
When Switching Power Supply is not affected by the influence of external magnetic field, reference voltage is provided according to set of frequency voltage；
When Switching Power Supply is influenced by external magnetic field, reference is provided according to set of frequency voltage and frequency adjustment difference in voltage
Voltage；
Periodically variable sawtooth voltage is provided；
According to the comparison result of reference voltage and sawtooth voltage, clock signal is provided to control the switch of master power switch frequency
Rate.
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| CN201610953347.7A CN106655823B (en) | 2016-11-03 | 2016-11-03 | Anti-magnetic interference switching power supply and control circuit and control method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610953347.7A CN106655823B (en) | 2016-11-03 | 2016-11-03 | Anti-magnetic interference switching power supply and control circuit and control method thereof |
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| CN106655823B true CN106655823B (en) | 2019-03-22 |
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| CN111478583B (en) * | 2020-04-24 | 2021-04-20 | 无锡芯朋微电子股份有限公司 | Switching power supply control circuit and switching power supply control method applying same |
| CN117174342B (en) * | 2023-11-03 | 2024-02-23 | 陕西星环聚能科技有限公司 | Device operating in pulsed magnetic field environment, control method thereof and nuclear fusion system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101557167A (en) * | 2009-02-25 | 2009-10-14 | 西南交通大学 | Bifrequency control method of switch power supply and device thereof |
| CN105070711A (en) * | 2015-08-18 | 2015-11-18 | 硅谷数模半导体（北京）有限公司 | Method and device for resisting electromagnetic interference |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101557167A (en) * | 2009-02-25 | 2009-10-14 | 西南交通大学 | Bifrequency control method of switch power supply and device thereof |
| CN105070711A (en) * | 2015-08-18 | 2015-11-18 | 硅谷数模半导体（北京）有限公司 | Method and device for resisting electromagnetic interference |
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