CN105529683B - A kind of secondary overpower-protection circuit and Switching Power Supply - Google Patents
A kind of secondary overpower-protection circuit and Switching Power Supply Download PDFInfo
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- CN105529683B CN105529683B CN201610089282.6A CN201610089282A CN105529683B CN 105529683 B CN105529683 B CN 105529683B CN 201610089282 A CN201610089282 A CN 201610089282A CN 105529683 B CN105529683 B CN 105529683B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/42—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to product of voltage and current
-
- 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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
- H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
-
- 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
- H02M1/0038—Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode control
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Voltage And Current In General (AREA)
Abstract
The present invention discloses a kind of secondary overpower-protection circuit, and it includes voltage follower circuit and voltage error amplifying circuit, and voltage follower circuit exports a voltage follow signal equal with voltage sampling signal to voltage error amplifying circuit；The voltage error amplifying circuit is used to sum to the output voltage signal of the voltage follow signal and Switching Power Supply, and the summing signal is realized to the closed-loop control of Switching Power Supply compared with reference voltage signal with one voltage signal of output；When summing signal is equal with reference voltage signal, the voltage error amplifying circuit is without output, default the reference voltage limitation voltage follow signal and the maximum allowable output voltage of Switching Power Supply are inverse change, the peak power output allowed so as to limit switch power supply, Switching Power Supply life time decay caused by overloading use is avoided, advantageously reduces the after-sales service expense of power supply product.
Description
Technical field
The present invention relates to switch power technology field, more particularly to a kind of secondary overpower-protection circuit and Switching Power Supply.
Background technology
Constant-current source circuit is often provided with Switching Power Supply, to ensure that Switching Power Supply still can under Width funtion input condition
Normal work.By taking LED drive power as an example (being hereinafter power supply), for the C-V characteristic of cooperated with LED, the power supply typically makes
The mode driven with constant current.Because LED product has diversity, most of power supply is designed to programmable mode, that is, passed through
Programmable mode sets output current, to meet the needs of different output parameters.When output current changes, if to ensure
Power supply maximum output voltage is constant, then typically has two kinds of designs：(1) peak power output of power supply is designed in maximum output
On electrical voltage point, maximum output current is equal to peak power output divided by maximum output voltage, is to work as LED product the shortcomings that the program
Practical application voltage when being more less than power supply maximum output voltage, the actual peak power output of power supply is smaller, and its value may be remote
Fully loaded power output during much smaller than the Power Management Design, because the higher price general charged of fully loaded power output of power supply is also higher, because
This, the cost performance of the power supply is relatively low；(2) design power supply in certain output voltage range can Maximum Power Output, namely
Maximum allowable output current changes with output voltage, and the output current allowed when output voltage is relatively low is higher, and this scheme lacks
It is that power supply is possible to be used by overpower to fall into, and long-term overpower use can reduce power source life.
The content of the invention
Technical problem solved by the invention is to provide a kind of secondary overpower-protection circuit, for Switching Power Supply, its
Simple in construction, the maximum allowable output voltage of the Switching Power Supply follows output current inverse change, so as to limit permission most
Big power output.
In order to solve the above technical problems, the present invention uses technical scheme as described below：
A kind of secondary overpower-protection circuit, for Switching Power Supply, the secondary overpower-protection circuit include voltage with
With circuit and voltage error amplifying circuit, wherein：
The input of the voltage follower circuit and the output current sampling end of Switching Power Supply connect and obtain one and switch
The voltage sampling signal of the output current equal proportion of power supply, the output end of the voltage follower circuit are then connected to voltage error amplification
Circuit, the voltage follower circuit export the voltage follow signal equal with the voltage sampling signal a to voltage error and put
Big circuit；
The voltage output side of the voltage error amplifying circuit and Switching Power Supply connects and the output of sampling switch power supply is electric
Pressure, the voltage error amplifying circuit have also accessed a default reference voltage signal, the output of the voltage error amplifying circuit
The prime power control circuit of connecting valve power supply is held, the voltage error amplifying circuit is used for the voltage follow signal and switch
The output voltage signal of power supply is summed, and by the summing signal compared with the reference voltage signal with output one
Voltage signal realizes the closed-loop control of Switching Power Supply；When summing signal is equal with the reference voltage signal, the voltage error
For amplifying circuit without output, the default reference voltage limits the voltage follow signal output electricity maximum allowable with Switching Power Supply
Press as inverse change, the peak power output allowed so as to limit switch power supply.
Further, the voltage follower circuit includes a NPN triode Q'1, and its base stage is connected by biasing resistor R'1
Voltage sampling signal end, NPN triode Q'1 colelctor electrode connect the feeder ear, and NPN triode Q'1 emitter stage passes through a biasing
Resistance R'2 is grounded, and input of its emitter stage also with voltage error amplifying circuit is connected.
Further, the voltage follower circuit includes an operational amplifier U2, and its in-phase input end is connected by resistance R'3
Voltage sampling signal Vref_I ends are connect, operational amplifier U2 inverting input is connected with its output end, the operational amplifier
The input of U2 output end connection voltage error amplifying circuit.
Further, the voltage follower circuit includes PNP triode Q1, NPN triode Q2, the PNP triode Q1
Base stage connect the voltage sampling signal end, its grounded collector, its emitter stage passes through biasing resistor R2 and feeder ear Vcc and connected
Connect, base stage of its emitter stage also with NPN triode Q2 is connected；The colelctor electrode of the NPN triode Q2 is connected with feeder ear Vcc,
Its emitter stage is grounded by biasing resistor R3, and its emitter stage is also connected with an input of voltage error amplifying circuit, described
PNP triode Q1, NPN triode Q2 be junction voltages are equal.
Further, voltage error amplifying circuit includes operational amplifier U1, resistance R4, resistance R5 and is connected to computing
Electric capacity C1 between amplifier U1 output ends and inverting input, the inverting input of the operational amplifier U1 pass through resistance R4
The output end of the voltage follower circuit is connected to, the input also passes through resistance R5 and the output voltage terminal of the Switching Power Supply
Connection, operational amplifier U1 in-phase input end are connected with default reference voltage terminal, operational amplifier U1 output
Hold the prime power control circuit for connecting valve power supply.
Further, voltage error amplifying circuit include operational amplifier U'1, resistance R'4, resistance R'5, resistance R'6 and
The electric capacity C'1 being connected between operational amplifier U'1 output ends and inverting input, the operational amplifier U'1's is same mutually defeated
Enter the output end that end is connected to the voltage follower circuit by resistance R'4, the input also passes through resistance R'5 and the switch
The output voltage terminal connection of power supply, operational amplifier U'1 inverting input pass through resistance R'6 and default reference voltage
End connection, operational amplifier U'1 output end are used for the prime power control circuit of connecting valve power supply.
Further, the voltage follower circuit includes a RC filter circuits, and resistance R11 one end of the RC filter circuits connects
The voltage sampling signal end is connected to, the other end is connected to PNP triode Q1 base stage, electric capacity C2 one end of the RC filter circuits
It is connected to PNP triode Q1 base stage, other end ground connection.
Further, the secondary overpower-protection circuit also includes voltage reference circuit, for producing default benchmark
Voltage, the voltage reference circuit include a NPN triode Q3, biasing resistor R17, voltage-regulator diode ZD1, the poles of NPN tri-
Pipe Q3 emitter stage is connected to operational amplifier U1A in-phase input end, and its base stage is connected to voltage-regulator diode ZD1 negative electrode,
Voltage-regulator diode ZD1 plus earth, the colelctor electrode of the NPN triode Q3 and the output voltage terminal of Switching Power Supply connect, partially
Resistance R17 is put to be connected between NPN triode Q3 base stage and colelctor electrode.
Further, a kind of Switching Power Supply, including main transformer T1, positioned at the power input of main transformer T1 primary sides
End, the prime power control circuit being connected with power input, positioned at the secondary control circuit of transformer T1 primary sides, Yi Jiyong
In the isolating device that the feedback signal of secondary control circuit is delivered to power control circuit, the secondary control circuit includes electricity
Flow control loop, voltage control loop, wherein, the voltage control loop includes the secondary of various structures as described above and crosses work(
Rate protection circuit, the voltage sampling signal are produced by current control loop.
Further, the secondary control circuit also includes diode D1, diode D2, the diode D2 negative electrode connect
The output end of current control loop is connected to, its anode is connected to the input of isolating device, the negative electrode connection of the diode D1
In the output end of voltage error amplifying circuit, its anode is connected to the input of isolating device.
The advantageous effects of the present invention are：The present invention secondary overpower-protection circuit include voltage follower circuit and
Voltage error amplifying circuit, the input of the voltage follower circuit and the output current sampling end of Switching Power Supply are connected and obtained
One is then connected to voltage with the voltage sampling signal of the output current equal proportion of Switching Power Supply, the output end of the voltage follower circuit
Error amplifying circuit, the voltage follower circuit export a voltage follow signal equal with the voltage sampling signal to the electricity
Press error amplifying circuit；The voltage output side of the voltage error amplifying circuit and Switching Power Supply connects and sampling switch power supply
Output voltage, the voltage error amplifying circuit have also accessed a default reference voltage signal, the voltage error amplifying circuit
Output end connecting valve power supply prime power control circuit, the voltage error amplifying circuit be used for the voltage follow signal
Summed with the output voltage signal of Switching Power Supply, and by the summing signal compared with the reference voltage signal with defeated
Go out the closed-loop control that a voltage signal realizes Switching Power Supply；When summing signal is equal with the reference voltage signal, the electricity
Pressing error amplifying circuit, it is maximum allowable with Switching Power Supply that the default reference voltage limits the voltage follow signal without output
Output voltage is inverse change, so as to the peak power output that limit switch power supply allows, avoids Switching Power Supply due to overload
Life time decay caused by use, advantageously reduce the after-sales service expense of power supply product.
Brief description of the drawings
Fig. 1 is the circuit diagram of secondary overpower-protection circuit in embodiment 1.
Fig. 2 is the circuit diagram of secondary overpower-protection circuit in example 2.
Fig. 3 is the circuit diagram of secondary overpower-protection circuit in embodiment 3.
Fig. 4 is the circuit diagram of secondary overpower-protection circuit in example 4.
Fig. 5 is the structural representation using Fig. 1 as a kind of Switching Power Supply of basic circuit.
Fig. 6 is the enlarged drawing of secondary control circuit in Fig. 5.
Fig. 7 is the enlarged drawing of current control loop in Fig. 6.
Fig. 8 is the enlarged drawing of secondary overpower-protection circuit in Fig. 7.
Fig. 9 is the structural representation using Fig. 4 as a kind of Switching Power Supply of basic circuit.
Figure 10 is the enlarged drawing of secondary control circuit in Fig. 9.
Embodiment
To make one of ordinary skill in the art that the object, technical solutions and advantages of the present invention be more clearly understood, with
Under the present invention is further elaborated in conjunction with the accompanying drawings and embodiments.
Embodiment 1
The secondary overpower-protection circuit of the present invention is applied in Switching Power Supply, with reference to shown in figure 1, time in embodiment 1
Level overpower-protection circuit includes voltage follower circuit 100 and voltage error amplifying circuit 200, wherein：
Voltage follower circuit 100 includes PNP triode Q1, NPN triode Q2, the PNP triode Q1 base stage connection
The voltage sampling signal Vref_I ends, its grounded collector, its emitter stage are connected by biasing resistor R2 with feeder ear Vcc,
Base stage of its emitter stage also with NPN triode Q2 is connected；The colelctor electrode connection feeder ear Vcc of the NPN triode Q2, it is launched
Pole is grounded by biasing resistor R3, and its emitter stage is also connected with an input of voltage error amplifying circuit.The voltage follow
Circuit 100 exports a voltage follow signal equal with the voltage sampling signal to the voltage error amplifying circuit.It is preferred that
, voltage follower circuit 100 also includes filter capacitor C2, and PNP triode Q1 base stage is connected with inter-collector by electric capacity C2,
To filter out high-frequency interferencing signal.
Voltage error amplifying circuit 200 includes operational amplifier U1, resistance R4, resistance R5 and is connected to operational amplifier
Electric capacity C1 between U1 output ends and inverting input, the inverting input of the operational amplifier U1 are connected to by resistance R4
The output end of the voltage follower circuit 100, the input also pass through resistance R5 and the output voltage Vo ends of the Switching Power Supply
Connection, operational amplifier U1 in-phase input end are connected with default reference voltage V ref_V ends.Operational amplifier U1's
The prime power control circuit of output end connecting valve power supply, for realizing the closed-loop control of Switching Power Supply.Voltage error amplifies
Circuit 200 limits the voltage sampling signal Vref_I using the default reference voltage V ref_V to be permitted with Switching Power Supply maximum
Perhaps output voltage is inverse change, so as to limit the peak power output of permission.
The operation principle of the secondary overpower-protection circuit is as follows：
V1=Vref_I+Vbe_Q1 (1)
Wherein, V1 represents node V1 voltage, and Vref_I represents the voltage at voltage sampling signal Vref_I ends, Vbe_Q1 tables
Show PNP triode Q1 be junction voltages.
V2=V1-Vbe_Q2 (2)
Wherein, V1 represents node V1 voltage, and V2 represents node V2 voltage, and Vbe_Q2 represents NPN triode Q2 be
Junction voltage.From formula (1), formula (2):
V2=Vref_I+Vbe_Q1-Vbe_Q2 (3)
When PNP triode Q1, NPN triode Q2 be junction voltages are equal, preferably PNP triode Q1, NPN triode Q2
For homologous series, with the device of brand, then be junction voltages approximately equal, is obtained：
V2=Vref_I (4)
From formula (4), the voltage at voltage sampling signal Vref_I ends is equal to the electricity that voltage follow signal is node V2
Pressure, the output current equal proportion of node V2 voltage follow Switching Power Supply increased or decrease.
Operational amplifier U1 resistance R4, resistance R5, electric capacity C1 constitute profound and negative feedbck, by the " empty of operational amplifier U1
It is short " characteristic understand：
V3=Vref_V (5)
Wherein, V3 represents node V3 voltage, and Vref_V represents default reference voltage.
It can be seen from voltage divider principle:
Wherein, R4, R5 represent resistance R4, resistance R5 resistance respectively.
Formula (4), formula (5) are substituted into formula (6) and can obtained：
Arrangement can obtain：
It can be seen that resistance R4, resistance R5, reference voltage terminal Vref_V are set into particular value, the output of the Switching Power Supply is set
During electric current increase, voltage sampling signal Vref_I increases, the maximum output voltage Vo that the Switching Power Supply allows can be reduced, so that
The change for obtaining Switching Power Supply peak power output reduces, the maximum output voltage and the reverse change of output current that Switching Power Supply allows
Change can compensate the peak power increase problem caused by output current unilaterally increases, so as to limit the maximum defeated of permission
Go out power, avoid Switching Power Supply life time decay caused by overloading use, advantageously reduce the dimension after sale of power supply product
Shield expense.In addition, the present invention secondary overpower-protection circuit circuit structure it is simple, without using complexity multiplier circuit,
Also it reduce further the manufacturing cost of power supply product.
Embodiment 2
In the 2nd kind of embodiment, voltage follower circuit 100 is also designed to other structures.It is described with reference to shown in figure 2
Voltage follower circuit includes a NPN triode Q'1, its base stage by biasing resistor R'1 connection voltage sampling signal Vref_I ends,
The emitter stage that NPN triode Q'1 colelctor electrode meets the feeder ear Vcc, NPN triode Q'1 is grounded by a biasing resistor R'2,
Input of its emitter stage also with voltage error amplifying circuit 200 is connected.Wherein：
V2=Vref_I-Vbe_Q'1 (9)
V2 represents node V2 voltage, and Vbe_Q'1 represents NPN triode Q'1 be junction voltages, and Vref_I represents that voltage is adopted
The voltage at sample signal Vref_I ends, when voltage sampling signal Vref_I is much larger than NPN triode Q'1 be junction voltages, such as
During Vref_I >=10 × Vbe_Q'1, NPN triode Q'1 be junction voltages can be neglected, obtain：
V2≈Vref_I (10)
It will be appreciated by those skilled in the art that, the maximum output that Switching Power Supply permission still can be obtained by deriving is electric
The inverse change of pressure and output current.
Embodiment 3
In the 3rd kind of embodiment, with reference to shown in figure 3, the voltage follower circuit 100 can also include an operational amplifier
U2, its in-phase input end pass through resistance R'3 connection voltage sampling signal Vref_I ends, operational amplifier U2 inverting input
It is connected with its output end, the input of operational amplifier U2 output end connection voltage error amplifying circuit 200.Wherein：
V2=Vref_I (11)
V2 represents node V2 voltage, and Vref_I represents the voltage at voltage sampling signal Vref_I ends, with Switching Power Supply
Output current equal proportion.It will be appreciated by those skilled in the art that, it still can obtain Switching Power Supply permission most by deriving
The inverse change of big output voltage and output current.
Embodiment 4
Certainly, in further embodiments, voltage error amplifying circuit 200 is also designed to other structures.With reference to figure 4
It is shown, in example 4, voltage error amplifying circuit also include operational amplifier U'1, resistance R'4, resistance R'5, resistance R'6,
And it is connected to the electric capacity C'1 between operational amplifier U'1 output ends and inverting input, the same phase of the operational amplifier U'1
Input is connected to the output end of the voltage follower circuit by resistance R'4, and the input is also opened by resistance R'5 with described
The output voltage Vo ends connection in powered-down source, the inverting input of the voltage error amplifying circuit 200 by resistance R'6 with it is default
Reference voltage terminal Vref_V connections, the output end of the voltage error amplifying circuit are used for the prime power control of connecting valve power supply
Circuit.It will be appreciated by those skilled in the art that, it can be obtained by derivation：
Wherein, V3 represents node V3 voltage, equal with reference voltage terminal Vref_V, and Vref_I represents current reference signal
The voltage at Vref_I ends, the output current equal proportion with Switching Power Supply, R4, R5 represent resistance R'4, resistance R'5 resistance respectively,
Vo represents the maximum output voltage that the Switching Power Supply allows.
It can be seen that resistance R'4, resistance R'5, resistance R'6, reference voltage terminal Vref_V are set to particular value, node V3 electricity
Press as particular value, then when setting the output current increase of the Switching Power Supply, the maximum output voltage that the Switching Power Supply allows can drop
It is low, so that the change of Switching Power Supply peak power output reduces, maximum output voltage and output electricity that Switching Power Supply allows
The inverse change of stream can compensate the peak power increase problem caused by output current unilaterally increases, fair so as to limit
Perhaps peak power output, Switching Power Supply life time decay caused by overloading use is avoided, advantageously reduces power supply production
The after-sales service expense of product.In addition, the secondary overpower-protection circuit circuit structure of the present invention is simple, without using multiplying for complexity
Adder circuit, it also reduce further the manufacturing cost of power supply product.
Embodiment 5
The various embodiments of above-mentioned secondary overpower-protection circuit can apply in existing Switching Power Supply product, in reality
Apply and a kind of structural representation of Switching Power Supply is shown in example 5, as shown in figure 5, the Switching Power Supply includes main transformer T1, is located at
The power input 10 of main transformer T1 primary sides, the prime power control circuit 20 being connected with power input 10, positioned at change
The secondary control circuit 30 of depressor T1 primary sides and the feedback signal of secondary control circuit 30 is delivered to prime power control
The photoelectrical coupler OC1 of circuit 20, so as to realize the control to output current or voltage.
In the present embodiment, alternating current Vac after rectifier bridge BR1 by exporting.
The prime power control circuit 20 includes master controller IC1, switching tube Q4 and some peripheral circuits.Master controller
IC1 is a kind of pwm chip, and its energization pins Pvcc is connected to the resistance R1 of two series connection, resistance R2 public point, resistance
The R1 other end is connected to power input positive pole, and the resistance R2 other end is connected to photoelectrical coupler OC1 4 pin, main control
Device IC1 energization pins Pvcc is also grounded by a filter capacitor C1.Master controller IC1 feedback signal pin FB is connected to light
Electric coupler OC1 3 pin, master controller IC1 output pin Out connecting valve pipes Q4 control terminal, master controller IC1 is also
With switching tube Q4 output end altogether.Switching tube Q4 input connection armature winding N1 the second end N12.Armature winding N1's
An absorbing circuit is also associated between first end N11 and the second end N12.
As shown in fig. 6, secondary control circuit 30, which includes output rectification filter electricity 31, current control loop 32, secondary, crosses work(
Rate protection circuit 33.
With reference to shown in Fig. 7, current control loop 32 includes operational amplifier U1B, divider resistance R21, the partial pressure electricity of series connection
R22 is hindered, operational amplifier U1B inverting input is connected to the output current sampling letter of Switching Power Supply by current-limiting resistance R20
Number VI_sen ends, divider resistance R21, the divider resistance R22 common port of operational amplifier U1B in-phase input end connection series connection
Point, i.e., the voltage sampling signal Vref_I ends shown in figure, voltage sampling signal Vref_I and current sampling signal VI_sen
Hold into equal proportion.Connected between operational amplifier U1B inverting input and output end by electric capacity C6.Operational amplifier U1B
Inverting input and output end between be also formed with by PI control circuits resistance R18, electric capacity C5 in series.
With reference to shown in Fig. 8, the secondary overpower-protection circuit 33 includes voltage follower circuit 331 and voltage error amplifies
Circuit 332, the voltage follower circuit 331 are used to voltage sampling signal Vref_I passing to voltage error amplifying circuit 332；
The voltage error amplifying circuit 332 limits the voltage sampling signal Vref_I using the default reference voltage V ref_V
It is inverse change with the maximum allowable output voltage of Switching Power Supply, so as to limit the peak power output of permission, its output end
The primary prime power control circuit 20 of connecting valve power supply, for realizing the closed-loop control of Switching Power Supply.Wherein：
Voltage follower circuit 331 can be basic circuit with the voltage follower circuit 100 in embodiment 1, including the poles of PNP tri-
Pipe Q1, NPN triode Q2, the PNP triode Q1 base stage connect the voltage sampling signal Vref_I ends, and its colelctor electrode connects
Ground, its emitter stage by the output voltage Vo ends of biasing resistor R12 and Switching Power Supply connect, its emitter stage also with NPN triode
Q2 base stage connection；The output voltage Vo ends of the colelctor electrode connecting valve power supply of the NPN triode Q2, its emitter stage connection electricity
Press the inverting input of error amplifying circuit 332.
It can be obtained through analysis：
Va=Vref_I (13)
Wherein, Va is node a voltage, and Vref_I is the Vref_I voltages of sampled signal.
Voltage follower circuit 331 in fig. 8 also includes a RC filter circuits, resistance R11 one end of the RC filter circuits
The voltage sampling signal Vref_I ends are connected to, the other end is connected to PNP triode Q1 base stage, the electricity of the RC filter circuits
Hold the base stage that C2 one end is connected to PNP triode Q1, other end ground connection.
Voltage error amplifying circuit 332 can be basic circuit with the voltage error amplifying circuit 200 in embodiment 1, bag
Include operational amplifier U1A, resistance R14, divider resistance R15, divider resistance R13 and be connected to operational amplifier U1 output ends and
The inverting input of electric capacity C4, the operational amplifier U1 between inverting input are connected to the NPN tri- by resistance R14
Pole pipe Q2 emitter stage, the inverting input are also attached to divider resistance R15, the divider resistance R13 public point b of series connection,
Wherein the divider resistance R15 other end is connected with the output voltage Vo ends of the Switching Power Supply, divider resistance R13 another termination
Ground.Operational amplifier U1A in-phase input end is connected with default reference voltage terminal Vref_V, operational amplifier U1A's
Output end connection photoelectrical coupler OC1 1 pin.As current loop, operational amplifier U1A inverting input and output end
Between the PI control circuits that can be formed with resistance R16, electric capacity C3.
Voltage sampling signal Vref_I has passed to voltage error amplifying circuit 332, computing by voltage follower circuit 331
Amplifier U1A sums to the output voltage Vo sampled signals and voltage sampling signal Vref_I of Switching Power Supply, operational amplifier U1A
Homophase input termination reference voltage signal Vref_V, from " empty short " characteristic of amplifier：
Vref_V=Vb (14)
Wherein, voltage on the basis of Vref_V, Vb are the voltage at divider resistance R15, divider resistance R13 public point b.
(Vo-Vref_V)/R15+ (Vref_I-Vref_V)/R14=Vref_V/R13 (15)
Wherein, R15, R13, R14 are respectively divider resistance R15, divider resistance R13, resistance R14 resistance.
Arrangement can obtain：
From formula (16), reference voltage terminal Vref_V is set to particular value, sets the output current of the Switching Power Supply to increase
Added-time, voltage sampling signal Vref_I increases, the maximum output voltage Vo that the Switching Power Supply allows can be reduced, so that switch
The change of power supply peak power output reduces, and the maximum output voltage and the inverse change of output current that Switching Power Supply allows can be with
Compensation peak power increase problem caused by output current unilaterally increases, so as to limit the maximum work output of permission
Rate, Switching Power Supply life time decay caused by overloading use is avoided, advantageously reduce the after-sales service expense of power supply product
With.In addition, the secondary overpower-protection circuit circuit structure of the present invention is simple, without using the multiplier circuit of complexity, also enter
One step reduces the manufacturing cost of power supply product.
Operational amplifier U1A output end signal is delivered to master controller IC1 by photoelectrical coupler OC1, due to switch
Electric power output voltage terminates to operational amplifier U1A inverting input, therefore, when Switching Power Supply actual output voltage is higher
When, operational amplifier U1A output reduces, and photoelectrical coupler OC1 input current reduces, so as to reduce photoelectrical coupler OC1
Output end current, reduce master controller IC1 feedback pin FB ends input current, master controller IC1 output duty cycle subtracts
It is small, so as to lifting switch electric power output voltage Vo, realize feedback closed loop control.
In certain embodiments, the secondary overpower-protection circuit 33 also includes voltage reference circuit 333, for producing
Default reference voltage V ref_V, in the embodiment shown in fig. 8, the voltage reference circuit 333 include a NPN triode
Q3, biasing resistor R17, voltage-regulator diode ZD1, the NPN triode Q3 emitter stage are connected to operational amplifier U1A same phase
Input, its base stage are connected to voltage-regulator diode ZD1 negative electrode, voltage-regulator diode ZD1 plus earth, the NPN triode
Q3 colelctor electrode and the output voltage Vo ends of Switching Power Supply connect, and biasing resistor R17 is connected to NPN triode Q3 base stage and collection
Between electrode.It can be obtained through analysis：
Vref_V=Vzd+Vbe_Q3 (17)
Wherein, Vref_V be default reference voltage voltage, Vzd be voltage-regulator diode ZD1 cathode voltage, Vbe_Q3
Represent NPN triode Q3 be junction voltages.
In the present embodiment, with reference to shown in Fig. 6, secondary control circuit 30 also includes diode D1, diode D2, and described two
Pole pipe D2 negative electrode is connected to the output end of current control loop 32, and its anode is connected to photoelectrical coupler OC1 input, institute
The negative electrode for stating diode D1 is connected to the output end of voltage error amplifying circuit 332, and its anode is connected to photoelectrical coupler OC1's
Input.It is low to the anti-of Switching Power Supply for operational amplifier U1A, operational amplifier U1B, output level by this design
Present loop and play control action, and both will not simultaneously participate in the feedback control of Switching Power Supply.Specifically, for example, work as Switching Power Supply
Output voltage Vo when being higher than a setting value, the level of operational amplifier U1A outputs reduces, and then passes through negative-feedback and causes master control
Device IC1 output duty cycles processed reduce, and to reduce the output voltage Vo of Switching Power Supply, form closed-loop control；Equally, Switching Power Supply is worked as
Output current when being more than a setting value, the level of operational amplifier U1B outputs reduces, and can equally be reduced by feedback control loop defeated
Go out electric current, form closed-loop control.So either voltage loop or current loop, the loop for first reaching preset value start to control making
With another amplifier amplifier exports high level, does not simultaneously participate in feedback control.
Embodiment 6
Another Switching Power Supply is shown in embodiment 6, as shown in figure 9, the Switching Power Supply includes main transformer T1, is located at
The power input 10 of main transformer T1 primary sides, the prime power control circuit 20 being connected with power input 10, positioned at change
The secondary control circuit 30 of depressor T1 primary sides and the feedback signal of secondary control circuit 30 is delivered to prime power control
The photoelectrical coupler OC1 of circuit 20, so as to realize the control to output current or voltage.It is whole that secondary control circuit 30 includes output
Flow filtered electrical 31, current control loop 32, secondary overpower-protection circuit 33.The secondary overpower-protection circuit 33 includes electricity
Pressure follows circuit 331 and voltage error amplifying circuit 332, voltage reference circuit 333.The present embodiment compared with Example 5, mainly
Difference is voltage error amplifying circuit 332 using circuit shown in embodiment 4 as basic circuit.In addition, current control loop
32 output end connection photoelectrical coupler OC1 1 pin.
As shown in Figure 10, in the present embodiment, the operational amplifier U'1A of voltage error amplifying circuit 332 homophase input
End is connected to the output end a of the voltage follower circuit by resistance R'14, passes through divider resistance R'15 and the Switching Power Supply
Output voltage Vo ends connection, be grounded by divider resistance R'13, the inverting input of the voltage error amplifying circuit 200 passes through
Resistance R'23 is connected with default reference voltage terminal Vref_V, the output end connection photoelectricity coupling of the voltage error amplifying circuit 200
Clutch OC1 2 pin.Connected between operational amplifier U'1A inverting input and output end by electric capacity C'4.Operational amplifier
The PI control circuits being made up of electric capacity C'3, resistance R'16 are additionally provided between U'1A inverting input and output end.This area
Technical staff by derivation it should be understood that can obtain：
Wherein, Vo represents that the output voltage of Switching Power Supply, Vb are divider resistance R ' 15, divider resistance R ' 13 public point
Voltage, the voltage at Vref_I expression current reference signal Vref_I ends at b, the output current equal proportion with Switching Power Supply,
R13, R14, R15 represent divider resistance R'13, resistance R'14, divider resistance R'15 resistance respectively.
From formula (18), divider resistance R'13, resistance R'14, divider resistance R'15, reference voltage terminal Vref_V are set
For particular value, the voltage at public point b is equal to reference voltage terminal Vref_V, and setting the output current of the Switching Power Supply increases
When, voltage sampling signal Vref_I increases, the maximum output voltage Vo that the Switching Power Supply allows can be reduced, so that switch electricity
The change of source peak power output reduces, and the maximum output voltage and the inverse change of output current that Switching Power Supply allows can be mended
The peak power increase problem caused by output current unilaterally increases is repaid, so as to limit the peak power output of permission,
Switching Power Supply life time decay caused by overloading use is avoided, advantageously reduces the after-sales service expense of power supply product.
In addition, the present invention secondary overpower-protection circuit circuit structure it is simple, without using complexity multiplier circuit, also further
Reduce the manufacturing cost of power supply product.
In the present embodiment, the output stage of operational amplifier U'1A output polarity and operational amplifier U1A in embodiment 5
Property on the contrary, the therefore output end connection photoelectrical coupler OC1 of the voltage error amplifying circuit 200 2 pin.It is so designed that, when opening
When the actual output voltage in powered-down source is higher, the level rise of operational amplifier U ' 1A outputs, photoelectrical coupler OC1 input electricity
Stream reduces, and then passing through negative-feedback reduces main controller IC1 output duty cycles, to reduce the reality output of Switching Power Supply electricity
Pressure, form closed-loop control.
The preferred embodiments of the present invention are these are only, rather than any formal limitation is done to the present invention.The skill of this area
Art personnel can impose various equivalent changes and improvement on the basis of above-described embodiment, all to be done within the scope of the claims
Equivalent variations or modification, it all should fall under the scope of the present invention.
Claims (10)
- A kind of 1. secondary overpower-protection circuit, for Switching Power Supply, it is characterised in that the secondary overpower-protection circuit bag Voltage follower circuit and voltage error amplifying circuit are included, wherein：The input of the voltage follower circuit and the output current sampling end of Switching Power Supply connect and obtain one and Switching Power Supply Output current equal proportion voltage sampling signal, the output end of the voltage follower circuit is then connected to voltage error amplification electricity Road, the voltage follower circuit export the voltage follow signal equal with the voltage sampling signal a to voltage error and amplified Circuit；The voltage output side of the voltage error amplifying circuit and Switching Power Supply connects and the output voltage of sampling switch power supply, institute State voltage error amplifying circuit and also access a default reference voltage signal, the output end connection of the voltage error amplifying circuit The prime power control circuit of Switching Power Supply, the voltage error amplifying circuit are used for the voltage follow signal and Switching Power Supply Output voltage signal is summed, and the summing signal is believed compared with the reference voltage signal with one voltage of output Number realize the closed-loop control of Switching Power Supply；When summing signal is equal with the reference voltage signal, voltage error amplification electricity Without output, it is anti-that the default reference voltage, which limits the voltage follow signal with the maximum allowable output voltage of Switching Power Supply, on road To change, the peak power output allowed so as to limit switch power supply.
- 2. secondary overpower-protection circuit as claimed in claim 1, it is characterised in that the voltage follower circuit includes one NPN triode Q'1, its base stage connect confession by biasing resistor R'1 connection voltage sampling signals end, NPN triode Q'1 colelctor electrode Electric end, NPN triode Q'1 emitter stage are grounded by a biasing resistor R'2, and NPN triode Q'1 emitter stage also misses with voltage The input connection of poor amplifying circuit.
- 3. secondary overpower-protection circuit as claimed in claim 1, it is characterised in that the voltage follower circuit can also wrap An operational amplifier U2 is included, its in-phase input end passes through resistance R'3 connection voltage sampling signal Vref_I ends, the operational amplifier U2 inverting input is connected with its output end, the input of operational amplifier U2 output end connection voltage error amplifying circuit End.
- 4. secondary overpower-protection circuit as claimed in claim 1, it is characterised in that the voltage follower circuit includes PNP Triode Q1, NPN triode Q2, the PNP triode Q1 base stage connect the voltage sampling signal end, PNP triode Q1 Grounded collector, PNP triode Q1 emitter stage is connected by biasing resistor R2 with feeder ear Vcc, PNP triode Q1 hair Base stage of the emitter-base bandgap grading also with NPN triode Q2 is connected；The colelctor electrode of the NPN triode Q2 is connected with feeder ear Vcc, the poles of NPN tri- Pipe Q2 emitter stage is grounded by biasing resistor R3, one also with voltage error amplifying circuit of NPN triode Q2 emitter stage Input connects, and the PNP triode Q1, NPN triode Q2 be junction voltages are equal.
- 5. secondary overpower-protection circuit as claimed in claim 1, it is characterised in that the voltage error amplifying circuit includes Operational amplifier U1, resistance R4, resistance R5 and the electric capacity being connected between operational amplifier U1 output ends and inverting input C1, the operational amplifier U1 inverting input are connected to the output end of the voltage follower circuit by resistance R4, described Operational amplifier U1 inverting input is also connected by resistance R5 with the output voltage terminal of the Switching Power Supply, the operation amplifier Device U1 in-phase input end is connected with default reference voltage terminal, and operational amplifier U1 output end is used for connecting valve power supply Prime power control circuit.
- 6. secondary overpower-protection circuit as claimed in claim 1, it is characterised in that voltage error amplifying circuit includes computing Amplifier U'1, resistance R'4, resistance R'5, resistance R'6 and it is connected between operational amplifier U'1 output ends and inverting input Electric capacity C'1, the in-phase input end of the operational amplifier U'1 is connected to the defeated of the voltage follower circuit by resistance R'4 Go out end, the in-phase input end of the operational amplifier U'1 is also connected by resistance R'5 and the output voltage terminal of the Switching Power Supply Connect, operational amplifier U'1 inverting input is connected by resistance R'6 with default reference voltage terminal, the operational amplifier U'1 output end is used for the prime power control circuit of connecting valve power supply.
- 7. secondary overpower-protection circuit as claimed in claim 4, it is characterised in that the voltage follower circuit includes a RC Filter circuit, resistance R11 one end of the RC filter circuits are connected to the voltage sampling signal end, and the other end is connected to PNP tri- Pole pipe Q1 base stage, electric capacity C2 one end of the RC filter circuits are connected to PNP triode Q1 base stage, other end ground connection.
- 8. secondary overpower-protection circuit as claimed in claim 1, it is characterised in that the voltage error amplifying circuit also wraps Voltage reference circuit is included, for producing default reference voltage, the voltage reference circuit includes a NPN triode Q3, biasing Resistance R17, voltage-regulator diode ZD1, the NPN triode Q3 emitter stage are connected to operational amplifier U1A in-phase input end, Its base stage is connected to voltage-regulator diode ZD1 negative electrode, voltage-regulator diode ZD1 plus earth, the current collection of the NPN triode Q3 The output voltage terminal of pole and Switching Power Supply is connected, and biasing resistor R17 is connected between NPN triode Q3 base stage and colelctor electrode.
- 9. a kind of Switching Power Supply, it is characterised in that the Switching Power Supply includes main transformer T1, positioned at main transformer T1 primary sides Power input, the prime power control circuit being connected with power input, positioned at transformer T1 primary sides secondary control Circuit, and for the feedback signal of secondary control circuit to be delivered to the isolating device of prime power control circuit, it is described secondary Level control circuit includes current control loop and the secondary overpower-protection circuit as described in claim 1~8, the voltage are adopted Sample signal is produced by current control loop.
- 10. Switching Power Supply as claimed in claim 9, it is characterised in that the secondary control circuit also includes diode D1, two Pole pipe D2, the diode D2 negative electrode are connected to the output end of current control loop, and its anode is connected to the defeated of isolating device Enter end, the negative electrode of the diode D1 is connected to the output end of the voltage error amplifying circuit, and its anode is connected to isolator The input of part.
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| CN201610089282.6A CN105529683B (en) | 2016-02-17 | 2016-02-17 | A kind of secondary overpower-protection circuit and Switching Power Supply |
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| CN201610089282.6A CN105529683B (en) | 2016-02-17 | 2016-02-17 | A kind of secondary overpower-protection circuit and Switching Power Supply |
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| CN105529683B true CN105529683B (en) | 2018-01-02 |
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| CN112730949B (en) * | 2020-12-21 | 2024-06-07 | 唐新颖 | High anti-interference Hall sensor |
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| TWI583114B (en) * | 2012-11-27 | 2017-05-11 | 通嘉科技股份有限公司 | Power controller with over power protection |
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| CN2586279Y (en) * | 2002-12-02 | 2003-11-12 | 深圳迈瑞生物医疗电子股份有限公司 | Overpower protective circuit of switch mode power |
| CN2796208Y (en) * | 2005-04-08 | 2006-07-12 | 崇贸科技股份有限公司 | Over-power protector |
| US7116565B1 (en) * | 2005-08-24 | 2006-10-03 | System General Corp. | Over-power protection apparatus for self-excited power converter |
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