CN108459645A - Constant current control loop and electronic load - Google Patents
Constant current control loop and electronic load Download PDFInfo
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- CN108459645A CN108459645A CN201710095338.3A CN201710095338A CN108459645A CN 108459645 A CN108459645 A CN 108459645A CN 201710095338 A CN201710095338 A CN 201710095338A CN 108459645 A CN108459645 A CN 108459645A
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
Abstract
The present invention provides a kind of constant current control loop and electronic loads, wherein the control loop includes：The output end of constant current error amplifying unit, first input end and differential amplification unit connects, and the second input terminal accesses constant current control voltage signal；Power cell group, includes the power cell of multiple parallel connections, and the input terminal of each power cell is connect with the output end of constant current error amplifying unit；Differential amplification unit includes：Current sampling resistor and difference amplifier；One end of current sampling resistor is connect with the output end of each power cell, the input terminal connection of the other end and difference amplifier；Difference amplifier, which is used to export each power cell to the voltage signal of the electric current generation of current sampling resistor, carries out differential amplification, is exported the voltage signal after differential amplification as feedback signal to constant current error amplifying unit.Above-mentioned technical proposal improves the control accuracy of constant current.
Description
Technical field
The present invention relates to constant current control technology field, more particularly to a kind of constant current control loop and Electronic Negative
It carries.
Background technology
In existing constant current control loop, constant current (CC, Constant are realized by power cell
Current control).For example, constant current control loop and the TaiWan, China Itech companies of TaiWan, China Chroma companies
Constant current control loop, as shown in Figure 1.
And the constant current control loop that the U.S. is moral company then uses more complicated structure realizes current constant control,
It increases a summation unit and error amplifying unit, circuit structure are as shown in Figure 2.
The operation principle of constant current control loop described above is introduced below.
The realization principle of power cell is broadly divided into reverse side feedback and in-phase end feedback in constant current control loop.
Power cell in the constant current control loop of Chroma companies is fed back using reverse side, circuit diagram such as Fig. 3 institutes
Show, V1 is an externally input power supply, and R4 is current sampling resistor.It controls voltage Vin and Mosfet (gold is driven by operational amplifier U1
Category-oxide semiconductor field effect transistor, Metal-Oxide-Semiconductor Field-Effect
Transistor) M1, and the ohmically current potential Vo of R4 are controlled according to proportion resistor R2 and R3, to realize current constant control I, control
Voltage processed can control multiple power cells simultaneously, so when n power cell parallel connection, output current is I × n, wherein Vo
It is as follows with the calculation formula of I：
The constant current control loop of Itech companies uses the power cell of in-phase end feedback principle, circuit diagram
As shown in figure 4, control voltage is equal to the voltage Vo=Vin on R8, to realize current constant control I.When the parallel connection of multiple power cells
When output current be I*n, wherein the calculation formula of I is as follows：
The realization principle for being moral company constant current control loop is also that reverse side is fed back, however, it is in current sample electricity
Difference amplifier U4 is increased on resistance R12, circuit diagram is as shown in Figure 5.
When multiple power cell parallel connections, differential voltage can be realized electricity by power cell by an adder unit
The summation of stream, circuit diagram is as shown in fig. 6, each frame with sense represents a power cell, I_sense_x generations
The differential voltage value that table is fed back to from x-th of power cell.
Voltage is controlled by error amplifier, compares the feedback of summation unit, and finally control the power list of multiple parallel connections
Member, to realize that current constant control, schematic diagram are as shown in Figure 7.
The defect of the above constant current control loop is described below.
In the technology being currently known, each power cell can generate error, error source master to the control of electric current
The potential difference that be derived between Power Groud and signal ground, the voltage error that amplifier generates, resistance error and temperature drift.If multiple
Power cell is in parallel, and error will add up, and whole constant-current control accuracy is caused the deviation of bigger occur, and this deviation is very
Difficulty is corrected by calibrating.
Potential difference between Power Groud and signal ground depends primarily on the conductor resistance between two ground, as shown in figure 8, letter
The conductor resistance Δ R1 of number ground (the GND marks for indicating F) between Power Groud causes to will produce potential difference between two ground, equivalent
For Vin+ Δ V, simultaneously as the conductor resistance Δ R2 of R4 ground connection, it is R4+ Δ R2 that can lead to the actual resistance of actual R4, in this way
The output current I after wire error is added, its error can add up after multiple power cell parallel connections, the calculation formula of electric current I
It is as follows：
Similarly, there is also the same problems for the power cell of the in-phase end feedback principle of Itech constant currents control loop.
The output current being added after wire error is I, and the cumulative of error, the calculating of electric current I can be caused after more power cell parallel connections
Formula is as follows：
But the power cell of the constant current control loop of moral company to current sampling resistor by using differential amplification
Method, effectively shielded wire resistance generate error source.But differential amplification unit is due to the mistake of operational amplifier itself
Voltage, temperature drift and noise are adjusted, output current can be caused to generate error.After power cell parallel connection, error can also add up.
Meanwhile three of the above solution can not make up the otherness that CC dynamics generate, CC dynamics are the one of electronic load
Kind operating mode makes the electric current of control realize the dynamic waveform of similar trapezoidal wave.Three of the above solution, power cell with
All there is error in operational amplifier and resistance capacitance between power cell, when with the same control voltage output dynamic waveform
When, dynamic waveform refers to the current waveform that each power cell generates, and the current time generated due to different power cells is not
Together, cause the dynamic waveform not exclusively to synchronize unanimously, that is, its can accordingly there is a situation where it is inconsistent, than if any power cell
Electric current settling time can be fast, and the electric current settling time of some power cells can be partially slow.
To sum up, constant current output being carried out using existing constant current control loop, control accuracy is low, meanwhile, power list
It is inconsistent to establish dynamic waveform for it after first parallel connection.
Invention content
An embodiment of the present invention provides a kind of constant current control loop, the control accuracy for improving constant current should
Control loop includes：Constant current error amplifying unit, power cell group and differential amplification unit, wherein constant current error
The first input end of amplifying unit and the output end of differential amplification unit connect, and the second input terminal accesses constant current and controls voltage
Signal；Power cell group, includes the power cell of multiple parallel connections, and input terminal and the constant current error of each power cell are amplified
The output end of unit connects；
Differential amplification unit includes：Current sampling resistor and difference amplifier；One end of current sampling resistor and each work(
The output end of rate unit connects, and the input terminal of the other end and difference amplifier connects；The output end of difference amplifier and constant electricity
The first input end of stream error amplifying unit connects, and difference amplifier is for exporting each power cell to current sampling resistor
Electric current generate voltage signal carry out differential amplification, exported the voltage signal after differential amplification as feedback signal to constant
Current error amplifying unit.
In one embodiment, power cell includes：
First operational amplifier, in-phase input end are connect with the output end of constant current error amplifying unit；
First capacitance, the first end of the first capacitance are connect with the inverting input of the first operational amplifier, the first capacitance
Second end is connect with the output end of the first operational amplifier；
First resistor, the first end of first resistor are connect with the inverting input of the first operational amplifier；First resistor
Second end is connect with power cell current sampling resistor；
The first transistor, grid are connect with the output end of the first operational amplifier, the second end of source electrode and first resistor and
The input terminal of differential amplification unit connects, and drains and is connect with the anode of external input power.
In one embodiment, power cell further includes：
Second resistance, the first end of second resistance are connect with the output end of the first operational amplifier；The second of second resistance
End is connect with the grid of the first transistor.
In one embodiment, power cell further includes：
The first end of 3rd resistor, 3rd resistor is connect with the output end of constant current error amplifying unit；3rd resistor
Second end connect with the in-phase input end of the first operational amplifier；
4th resistance, the homophase input of the first end of the 4th resistance and the second end and the first operational amplifier of 3rd resistor
End connection；The second end of 4th resistance is grounded.
In one embodiment, above-mentioned constant current control loop further includes：
The input terminal of driving unit, driving unit is connect with the output end of constant current error amplifying unit, driving unit
Output end connect with the input terminal of each power cell, for the constant current control that exports constant current error amplifying unit
Voltage signal processed exports after being amplified to power cell group.
In one embodiment, driving unit includes：
Second operational amplifier, the output of the in-phase input end and constant current error amplifying unit of second operational amplifier
End connection, inverting input and output end are connect with the input terminal of power cell group；
The input terminal of clamp circuit, clamp circuit is connect with the output end of constant current error amplifying unit, clamp circuit
Output end and second operational amplifier in-phase input end connect, for inhibit constant current error amplifying unit export mistake
Rush electric current.
In one embodiment, clamp circuit includes：
The first end of 5th resistance, the 5th resistance is connect with external power supply anode, second end and the constant electricity of the 5th resistance
The output end of stream error amplifying unit is connected with the in-phase input end of second operational amplifier；
The grid of second transistor, second transistor is connect with level control circuit, drain electrode and second operational amplifier
In-phase input end connects；
6th resistance, the first end of the 6th resistance and the source electrode of second transistor connect；
Diode, the cathode of diode are connect with the second end of the 6th resistance, the anode of diode and bearing for external power supply
Pole connects.
In one embodiment, diode is Zener diode.
In one embodiment, above-mentioned constant current control loop further includes：
Reversed amplifying unit, the input terminal of reversed amplifying unit and the output end of differential amplification unit connect, reversed to amplify
The output end of unit is connect with the first input end of constant current error amplifying unit, and reversed amplifying unit is for working as power cell
When group is in-phase end feedback, the differential amplified voltage signal that differential amplification unit exports reversely is amplified, will reversely be amplified
Voltage signal afterwards is exported as feedback signal to the constant current error amplifying unit.
Present invention implementation additionally provides a kind of electronic load, the control accuracy for improving constant current, the control loop
Including：Constant current control loop as described above.
In the prior art, in each power cell by difference amplifier to the current sampling resistor of the power cell
Voltage carries out differential amplification.Since difference amplifier amplifier itself generates offset voltage, by an electric current summation unit to more
The power cell of a parallel connections multiple in this way realizes that electric current is summed using adder, and error will add up, and lead to whole constant current
There is deviation in control accuracy.Meanwhile after power cell parallel connection its to establish dynamic waveform inconsistent.
Compared with prior art, the electric current of technical solution provided in an embodiment of the present invention, the output of power cell group passes through
On one precision current sampling resistor, then differential amplification is carried out to the voltage on the current sampling resistor, and will be after differential amplification
Voltage feedback signal compared with constant current control voltage signal, such technical solution, avoid power cell parallel connection
All errors are all concentrated on a precision current sampling resistor, it is defeated to improve constant current by generated accumulated error
The control accuracy gone out.
Simultaneously as the electric current summation to all parallel power units is realized by precision current sampling resistor, and
The voltage that electric current after precision current sampling resistor generates does differential amplification by difference amplifier, constant electricity entire in this way
The behavioral characteristics of flow control circuit all concentrate in the dynamic parameter of constant current error amplifying unit, are moved to the control loop
State has carried out normalized, it establishes consistent dynamic waveform after power cell parallel connection has been achieved.
To sum up, technical solution provided in an embodiment of the present invention improves the control accuracy and power cell of constant current output
It establishes the consistency of dynamic waveform after parallel connection.
Description of the drawings
Attached drawing described herein is used to provide further understanding of the present invention, and is constituted part of this application, not
Constitute limitation of the invention.In the accompanying drawings：
Fig. 1 is the constant current control loop of TaiWan, China Chroma companies and Itech companies in the prior art of the invention
Structural schematic diagram；
Fig. 2 be the present invention in the prior art the U.S. be moral company constant current control loop structural schematic diagram；
Fig. 3 is that the realization of the power cell in the constant current control loop of Chroma companies in the prior art of the invention is former
Manage schematic diagram；
Fig. 4 is the realization principle schematic diagram of the constant current control loop of Itech companies in the prior art of the invention；
Fig. 5 is the realization principle schematic diagram that the present invention is in the prior art moral company constant current control loop；
Fig. 6, which is the present invention, to be realized when being multiple power cell parallel connections of moral company constant current control loop in the prior art
Principle schematic；
Fig. 7 is the structural schematic diagram that the present invention is in the prior art moral company constant current control loop；
Fig. 8 is power cell error source schematic diagram in constant current control loop in the prior art of the invention；
Fig. 9 is the structural schematic diagram of constant current control loop in the embodiment of the present invention；
Figure 10 is the structural schematic diagram of constant current control loop in one embodiment of the invention；
Figure 11 is the structural schematic diagram of constant current error amplifying unit in the embodiment of the present invention；
Figure 12 is the structural schematic diagram of driving unit in the embodiment of the present invention；
Figure 13 is the structural schematic diagram of power cell in the embodiment of the present invention；
Figure 14 is the structural schematic diagram of differential amplification unit in the embodiment of the present invention；
Figure 15 is the structural schematic diagram of differential amplification unit in the embodiment of the present invention being connect with power cell；
Figure 16 is the structural schematic diagram of reversed amplifying unit in the embodiment of the present invention；
Figure 17 is the principle schematic that power cell uses reverse side feedback in the embodiment of the present invention.
Specific implementation mode
To make the objectives, technical solutions, and advantages of the present invention clearer, right with reference to embodiment and attached drawing
The present invention is described in further details.Here, the exemplary embodiment and its explanation of the present invention be for explaining the present invention, but simultaneously
It is not as a limitation of the invention.
The purpose of this programme is to solve accumulated error caused by multiple power cell parallel connections, while increasing power cell
It establishes the consistency of dynamic waveform after parallel connection.
It is an advantage of the invention that the electric current in power cell is all aggregated on a precision current sampling resistor, then to it
Differential amplification is carried out, and this signal is fed back into CC error amplifiers, is compared with control signal, then is exported to multigroup parallel connection
The control signal of power cell.This topology can effectively avoid error accumulation caused by power cell parallel connection, and by institute
Some errors all collect on an accurate current sampling resistor.
Normalized is also achieved to the dynamic of control loop simultaneously, because the signal of feedback itself is achieved that institute
There are the summation of parallel power cell current, the dynamic characteristic of control loop all to concentrate on the dynamic parameter of CC error amplifying units
On.It describes in detail below to the constant current control loop.
Fig. 9 is the structural schematic diagram of constant current control loop in the embodiment of the present invention, as shown in figure 9, the control loop
Including：Constant current error amplifying unit, power cell group and differential amplification unit, wherein
The first input end of constant current error amplifying unit and the output end of differential amplification unit connect, the second input terminal
Constant current control voltage signal is accessed, constant current error amplifying unit is used for constant current control voltage signal and difference
The feedback signal of amplifying unit is compared, fault in enlargement, according to the error of amplification, the constant current control after output error adjustment
Voltage signal processed is exported to power cell group；
Power cell group includes the power cell of multiple parallel connections, input terminal and the constant current error of each power cell
The output end of amplifying unit connects, and power cell group is used for according to the constant current control voltage signal after error transfer factor, output
Constant current；
Differential amplification unit, the input terminal of differential amplification unit are connect with the output end of each power cell；Differential amplification
Unit includes：Current sampling resistor and difference amplifier；One end of current sampling resistor and the output end of each power cell connect
It connects, the other end is connect with the input terminal of the difference amplifier；The output end of difference amplifier and the amplification of constant current error are single
The first input end connection of member, difference amplifier are used to export each power cell to the electric current generation of current sampling resistor
Voltage signal carries out differential amplification, and the voltage signal after differential amplification is exported as feedback signal to constant current error and is amplified
Unit.
In the prior art, in each power cell by difference amplifier to the current sampling resistor of the power cell
Voltage carries out differential amplification.Since difference amplifier amplifier itself generates offset voltage, by an electric current summation unit to more
The power cell of a parallel connections multiple in this way realizes that electric current is summed using adder, and error will add up, and lead to whole constant current
There is deviation in control accuracy.Meanwhile after power cell parallel connection its to establish dynamic waveform inconsistent.
Compared with prior art, the electric current of technical solution provided in an embodiment of the present invention, the output of power cell group passes through
On one precision current sampling resistor, then differential amplification is carried out to the voltage on the current sampling resistor, and will be after differential amplification
Voltage feedback signal compared with constant current control voltage signal, such technical solution, avoid power cell parallel connection
All errors are all concentrated on a precision current sampling resistor, it is defeated to improve constant current by generated accumulated error
The control accuracy gone out.
Simultaneously as the electric current summation to all parallel power units is realized by precision current sampling resistor, and
The voltage that electric current after precision current sampling resistor generates does differential amplification by difference amplifier, constant electricity entire in this way
The behavioral characteristics of flow control circuit all concentrate in the dynamic parameter of constant current error amplifying unit, are moved to the control loop
State has carried out normalized, it establishes consistent dynamic waveform after power cell parallel connection has been achieved.
To sum up, technical solution provided in an embodiment of the present invention improves the control accuracy and power cell of constant current output
It establishes the consistency of dynamic waveform after parallel connection.
As shown in Figure 10, in one embodiment, above-mentioned constant current control loop can also include：
The input terminal of driving unit, driving unit is connect with the output end of constant current error amplifying unit, driving unit
Output end connect with the input terminal of each power cell, for the constant current control that exports constant current error amplifying unit
Voltage signal processed exports after being amplified to power cell group.
As shown in Figure 10, in one embodiment, above-mentioned constant current control loop can also include：
Reversed amplifying unit, the input terminal of reversed amplifying unit and the output end of differential amplification unit connect, reversed to amplify
The output end of unit is connect with the first input end of constant current error amplifying unit, and reversed amplifying unit is for working as power cell
When group is in-phase end feedback, the differential amplified voltage signal that differential amplification unit exports reversely is amplified, will reversely be amplified
Voltage signal afterwards is exported as feedback signal to the constant current error amplifying unit.
Each unit in the embodiment of the present invention is described in detail below as follows.
First, in conjunction with attached drawing 11, constant current error amplifying unit is introduced.
As shown in figure 11, constant current error amplifying unit includes：7th resistance R117, the 8th resistance R125, the 9th electricity
Hinder R122, the second capacitance C53 and error amplifier U13；Wherein, the first end of the 7th resistance R117 (amplify by constant current error
The first input end of unit) access constant current control voltage signal；The in-phase input end of error amplifier U13 passes through a resistance
R115 is grounded, second end, the first end of the 8th resistance R125 of the inverting input of error amplifier U13 and the 7th resistance R117
It is connected with the first end of the second capacitance C53, the output end of error amplifier U13 is connect with the input terminal of each power cell；The
The second end (first input end of constant current error amplifying unit) of eight resistance R125 connects with the output end of differential amplification unit
It connects, accesses feedback signal；The second end of second capacitance C53 is connect with the first end of the 9th resistance R122；9th resistance R122's
Second end is connect with the output end of error amplifier U13.
When it is implemented, constant current error amplifying unit is to carry out constant current control voltage signal and feedback signal
Compare amplification, to generate the signal of control power cell, wherein R117 and R125 and C53 and this four capacitance-resistance lists of R122
Member determines the dynamic parameter of CC control loops, this includes the dominant pole and zero of control loop, and wherein dominant pole determines
The bandwidth of the control loop.
Secondly, in conjunction with attached drawing 12, driving unit is introduced.
In one embodiment, driving unit includes：
The in-phase input end 8 of second operational amplifier U12A, second operational amplifier U12A amplify with constant current error
The output end of unit connects, and inverting input 9 is connect with output end 10, constitutes follower, second operational amplifier U12A's is defeated
Outlet 10 is connect with the input terminal of each power cell；
The input terminal of clamp circuit, clamp circuit is connect with the output end of constant current error amplifying unit, clamp circuit
Output end connect with the in-phase input end 8 of second operational amplifier U12A, for inhibiting constant current error amplifying unit defeated
The overshoot current gone out.
In one embodiment, clamp circuit includes：
The first end of 5th resistance R111, the 5th resistance R111 are connect with external power supply anode, and the of the 5th resistance R111
Two ends are connect with the in-phase input end 8 of the output end of constant current error amplifying unit and second operational amplifier U12A；
The grid 11 of second transistor Q18, second transistor Q18 are connect with level control circuit, drain electrode 12 and the 5th electricity
Hinder second end, the output end of constant current error amplifying unit and the in-phase input end 8 of second operational amplifier U12A of R111
Connection；
6th resistance R119, the first end of the 6th resistance R119 are connect with the source electrode 13 of second transistor Q18；
The cathode 14 of diode D40, diode D40 are connect with the second end of the 6th resistance R119, the anode of diode D40
15 connect with the cathode of external power supply.
In one embodiment, diode D40 is Zener diode.
When it is implemented, the control signal of constant current error amplifying unit output is also needed to through over-drive unit, driving
The function of unit is increased output current, and typical circuit is the follower of an amplifier, in order to can be driven more
Power cell.A clamp circuit is further comprised inside driving unit simultaneously, for limiting overshoot current, figure institute specific as follows
Show, U12A is the follower of an amplifier, and R111, Q18, R119 and D40 (Zener diode) constitute a basic clamped electricity
Road, the amplitude of clamped voltage are consistent with the voltage of Zener diode.That is, clamp circuit includes R111, Q18, R119 and D40,
And the control circuit of Q18, when the base stage of Q18 receives logic level 1, then clamp circuit is effective, can be the same phase of amplifier 12
It holds (8 foot), is pulled to negative voltage by force, thus output current is made to be reduced to 0A.It only needs to the electricity of the base stage supply 0 or 1 of Q18
It is flat, you can making clamp circuit, effectively or in vain (" level control circuit " mentioned above is played supplies 0 to the base stage of Q18
Or 1 level, you can keep clamp circuit effective or invalid effect).Clamp circuit improves the constant current control ring
The safety on road.
Then, in conjunction with attached drawing 13, power cell is introduced.
In one embodiment, power cell includes：
First operational amplifier U86B, in-phase input end 5 are connect with the output end of constant current error amplifying unit；
First capacitance C12, the first end of the first capacitance C12 are connect with the inverting input 6 of the first operational amplifier U86B,
The second end of first capacitance C12 is connect with the output end 7 of the first operational amplifier U86B；
First resistor R40, the first end and the first operational amplifier of the first end of first resistor R40 and the first capacitance C12
The inverting input 6 of U86B connects；The second end of first resistor R40 connects with the first end of power cell current sampling resistor R48
It connects；
The second end of the output end 7 and the first capacitance C12 of the first transistor Q8, grid 1 and the first operational amplifier U86B
Connection, source electrode 3 are connect with the second end of first resistor R40 and power cell current sampling resistor R48, power cell current sample
The second end of resistance R48 and the input terminal of differential amplification unit connect, and the anode of drain electrode 2 and external input power is (in such as Figure 15
The anode of V4) connection.
When it is implemented, as shown in figure 13, in power cell, the first capacitance C12 and first resistor R40 are used for adjusting first
The speed of operational amplifier U86B improves the working efficiency of power cell.
In one embodiment, power cell further includes：
Second resistance R445, the output end 7 and first of the first end of second resistance R445 and the first operational amplifier U86B
The second end of capacitance C12 connects；The second end of second resistance R445 is connect with the grid 1 of the first transistor Q8.
When it is implemented, as shown in figure 13, being previously mentioned in power cell, the first capacitance C12 and first resistor R40 are used
The speed of the first operational amplifier U86B is adjusted, while improving the first operational amplifier U86B speed, in order to make first
The work of operational amplifier U86B tends towards stability, and is provided with second resistance R445.Pass through second resistance R445 and the first transistor
The common cooperation of Q8 (in production, having selected suitable parameter as needed) adjusts the stabilization of the first operational amplifier U86B
Property, it realizes while improving the working efficiency of power cell, and improve the safety of power cell.
In one embodiment, power cell further includes：
The first end of 3rd resistor R441,3rd resistor R441 are connect with the output end of constant current error amplifying unit；
The second end of 3rd resistor R441 is connect with the in-phase input end 5 of the first operational amplifier U86B；
4th resistance R24, the first end of the 4th resistance R24 and the second end of 3rd resistor R441 and the first operational amplifier
The in-phase input end 5 of U86B connects；The second end of 4th resistance R24 is grounded.
When it is implemented, as shown in figure 13, voltage Iprog is very high voltage, the electricity of 3rd resistor R441 and the 4th is utilized
The bleeder circuit that R24 is formed is hindered, the voltage that TP95 is pointed out in the voltage and Figure 13 of the first operational amplifier U86B is made to reach unanimity,
It is such to design the safety that ensure that power cell, and then improve the safety of entire constant current control loop.
When it is implemented, power cell group is that multiple power cells are in parallel, to realize the electric current of control bigger, single power
The diagram of unit such as 13, principle are the voltage controlled current sources of an in-phase end feedback control, control voltage IProg by R441 and
R24 is divided, and the grid of MSOFET is controlled using amplifier, makes MOSFET output currents and is generated on current sampling resistor R48
Voltage, and this voltage feeds back to the first operational amplifier U86B again, makes a control loop, and the final electric current that controls is adopted
The current potential of sample resistance R48, exports a constant current, and calculated value is：
Multiple power cell parallel connections power cell group has just been integrated into.
Then, in conjunction with attached drawing 14 and 15, differential amplification unit is introduced.
When it is implemented, differential amplification unit includes：Current sampling resistor R129 and difference amplifier U15.Specific connection
Mode is：
Current sampling resistor R129 walks electric current by four line connection types, both threads, and both threads walk voltage.Wherein, the leakage of electricity
One end of stream is connect with the output end of each power cell, and the other end is then the output port of electrical load devices, and connection is outer
The negative terminal (i.e. the cathode of V4 in Figure 15) of portion's input power；The input terminal of the both threads and difference amplifier of walking voltage connects,
That is two be connected to resistance R127 first ends and R130 first ends be exactly the line of voltage sampling, and connect power cell
Output line and connection outside input line be then to walk the line of electric current.
The inverting input 2 of difference amplifier U15 is connect with the second end of resistance R127, the same phase of difference amplifier U15
Input terminal 3 is connect with the second end of resistance R130.
It is eventually aggregated on a precision current sampling resistor R129, is equivalent to pair simultaneously from power cell group outflow electric current
Electric current is summed caused by all power cells of connection, and uniformly does differential amplification.The detailed circuit of differential amplification unit
As shown in figure 14.
Finally, in conjunction with attached drawing 16, reversed amplifying unit is introduced.
In order to ensure that entire control loop is negative feedback control loop, so, it is also necessary to the letter for exporting this differential amplification
Number reversed amplification is done, then feed back to CC error amplifying units again, entire control loop is made to form negative-feedback.
CC controls signal and compares amplification by CC error amplifying units U13 with summation current feedback signal, and exports control
The voltage signal of power cell processed, this signal also needs to increase output current by driving unit U12A, to drive more work(
The output signal of rate unit, driving unit controls each work(in power cell group (PowerStage-300W_1, as shown in figure 15)
The electric current of rate unit output, and the output current of each power cell is eventually summarised on current sampling resistor R129, is made
R129 generates a voltage, and the difference amplifier built by U15 does differential amplification to the potential difference on R129, this differential amplification
Signal finally feeds back to CC error amplifiers U13 by the sign-changing amplifier of U16 again so that CC controls voltage and sign-changing amplifier
The feedback signal of output compares amplification, and reversed amplified voltage signal is exported as feedback signal to the constant current
A complete CC feedback control loop is consequently formed in error amplifying unit.
It, can be by driving unit circuit deletion if the power cell of driving is fewer in this control loop.If work(
Rate unit is by the way of reverse side feedback, and as shown in figure 17, then the reversed amplifying unit in control loop can also be according to negative
Feedback principle is deleted.
Based on same inventive concept, a kind of electronic load is additionally provided in the embodiment of the present invention, such as the following examples institute
It states.Since the principle that electronic load solves the problems, such as is similar to constant current control loop, the implementation of electronic load can be joined
See the implementation of constant current control loop, overlaps will not be repeated.Used below, term " unit " or " module " can
To realize the combination of the software and/or hardware of predetermined function.Although device described in following embodiment is preferably come with software
It realizes, but the realization of the combination of hardware or software and hardware is also that may and be contemplated.
Present invention implementation additionally provides a kind of electronic load, the control accuracy for improving constant current, the control loop
Including：Constant current control loop as described above.
Technical solution provided in an embodiment of the present invention reaches following advantageous effects：
The most important improvement of the present invention is with a precision current sampling resistor to produced by multiple parallel power units
Electric current sum, and do and feed back, while control is normalized in the feedback signal that CC control signals sum to electric current.
His the advantages of is to shield error accumulation caused by multiple power cells in parallel, and error is concentrated on summing
On the accurate sampling resistor of one of electric current and its differential amplifier circuit.The control essence of output current can be greatly improved in this way
Degree.
Meanwhile CC control signals are to carry out application condition by the feedback signal that electric current is summed, so entire control ring
The dynamic characteristic on road all concentrates on the circuit of CC error amplifying units.As described above, the dynamic characteristic of entire control loop
All by error amplifying unit capacitance and resistance (R117, R125 and C53 and R122 this four capacitor resistor units) determine.This
Sample makes the dynamic characteristic difference that ensure that consistency, compensate between power cell of entire control loop.
Obviously, those skilled in the art should be understood that each module of the above-mentioned embodiment of the present invention or each step can be with
It is realized with general computing device, they can be concentrated on a single computing device, or be distributed in multiple computing devices
On the network formed, optionally, they can be realized with the program code that computing device can perform, it is thus possible to by it
Store and be performed by computing device in the storage device, and in some cases, can be to be held different from sequence herein
The shown or described step of row, either they are fabricated to each integrated circuit modules or will be multiple in them
Module or step are fabricated to single integrated circuit module to realize.In this way, the embodiment of the present invention be not limited to it is any specific hard
Part and software combine.
The foregoing is only a preferred embodiment of the present invention, is not intended to restrict the invention, for the skill of this field
For art personnel, the embodiment of the present invention can have various modifications and variations.All within the spirits and principles of the present invention, made by
Any modification, equivalent substitution, improvement and etc. should all be included in the protection scope of the present invention.
Claims (10)
1. a kind of constant current control loop, which is characterized in that including：Constant current error amplifying unit, power cell group and
Differential amplification unit, wherein the first input end of constant current error amplifying unit and the output end of differential amplification unit connect,
Second input terminal accesses constant current control voltage signal；Power cell group includes the power cell of multiple parallel connections, each power
The input terminal of unit is connect with the output end of constant current error amplifying unit；
The differential amplification unit includes：Current sampling resistor and difference amplifier；One end of the current sampling resistor with it is every
The output end of a power cell connects, and the other end is connect with the input terminal of the difference amplifier；The difference amplifier it is defeated
Outlet is connect with the first input end of the constant current error amplifying unit, and the difference amplifier is used for each power list
The voltage signal that the electric current of member output to current sampling resistor generates carries out differential amplification, and the voltage signal after differential amplification is made
It is exported to the constant current error amplifying unit for feedback signal.
2. constant current control loop as described in claim 1, which is characterized in that the power cell includes：
First operational amplifier (U86B), in-phase input end (5) are connect with the output end of constant current error amplifying unit；
First capacitance (C12), the inverting input of the first end and the first operational amplifier (U86B) of first capacitance (C12)
(6) it connects, the second end of the first capacitance (C12) is connect with the output end (7) of the first operational amplifier (U86B)；
First resistor (R40), the inverting input of the first end and the first operational amplifier (U86B) of the first resistor (R40)
(6) it connects；The second end of first resistor (R40) is connect with power cell current sampling resistor (R48)；
The first transistor (Q8), grid (1) are connect with the output end (7) of the first operational amplifier (U86B), source electrode (3) and first
The second end of resistance (R40) is connected with the input terminal of differential amplification unit, and drain electrode (2) is connect with the anode of external input power.
3. constant current control loop as claimed in claim 2, which is characterized in that the power cell further includes：
Second resistance (R445), the output end of the first end and the first operational amplifier (U86B) of the second resistance (R445)
(7) it connects；The second end of the second resistance (R445) is connect with the grid (1) of the first transistor (Q8).
4. constant current control loop as claimed in claim 2, which is characterized in that the power cell further includes：
3rd resistor (R441), the first end of the 3rd resistor (R441) connect with the output end of constant current error amplifying unit
It connects；The second end of 3rd resistor (R441) is connect with the in-phase input end (5) of the first operational amplifier (U86B)；
4th resistance (R24), the second end and first of the first end and the 3rd resistor (R441) of the 4th resistance (R24)
The in-phase input end (5) of operational amplifier (U86B) connects；The second end of 4th resistance (R24) is grounded.
5. constant current control loop as described in claim 1, which is characterized in that further include：
Driving unit, the input terminal of the driving unit are connect with the output end of the constant current error amplifying unit, driving
The output end of unit is connect with the input terminal of each power cell, the constant electricity for exporting constant current error amplifying unit
Flow control voltage signal exports after being amplified to power cell group.
6. constant current control loop as claimed in claim 5, which is characterized in that the driving unit includes：
Second operational amplifier (U12A), in-phase input end (8) and the constant current of the second operational amplifier (U12A) miss
The output end of poor amplifying unit connects, and inverting input (9) and output end (10) are connect with the input terminal of power cell group；
The input terminal of clamp circuit, the clamp circuit is connect with the output end of constant current error amplifying unit, clamp circuit
Output end connect with the in-phase input end (8) of second operational amplifier (U12A), for inhibiting the amplification of constant current error single
The overshoot current of member output.
7. constant current control loop as claimed in claim 6, which is characterized in that the clamp circuit includes：
The first end of 5th resistance (R111), the 5th resistance (R111) is connect with external power supply anode, the 5th resistance (R111)
Second end connects with the output end of constant current error amplifying unit and the in-phase input end (8) of second operational amplifier (U12A)
It connects；
The grid (11) of second transistor (Q18), the second transistor (Q18) is connect with level control circuit, is drained (12)
It is connect with the in-phase input end (8) of second operational amplifier (U12A)；
6th resistance (R119), the first end of the 6th resistance (R119) are connect with the source electrode (13) of second transistor (Q18)；
The cathode (14) of diode (D40), the diode (D40) is connect with the second end of the 6th resistance (R119), diode
(D40) anode (15) is connect with the cathode of external power supply.
8. constant current control loop as claimed in claim 7, which is characterized in that the diode (D40) is two pole of Zener
Pipe.
9. constant current control loop as described in claim 1, which is characterized in that further include：
The input terminal of reversed amplifying unit, the reversed amplifying unit is connect with the output end of the differential amplification unit, reversely
The output end of amplifying unit is connect with the first input end of constant current error amplifying unit, and the reversed amplifying unit is for working as
When power cell group is in-phase end feedback, the differential amplified voltage signal that differential amplification unit exports reversely is amplified, it will
Reversed amplified voltage signal is exported as feedback signal to the constant current error amplifying unit.
10. a kind of electronic load, which is characterized in that including：Constant current as described in claim 1 to 9 any claim
Control loop.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710095338.3A CN108459645A (en) | 2017-02-22 | 2017-02-22 | Constant current control loop and electronic load |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710095338.3A CN108459645A (en) | 2017-02-22 | 2017-02-22 | Constant current control loop and electronic load |
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| CN108459645A true CN108459645A (en) | 2018-08-28 |
Family
ID=63222024
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710095338.3A Pending CN108459645A (en) | 2017-02-22 | 2017-02-22 | Constant current control loop and electronic load |
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| CN109061538A (en) * | 2018-09-12 | 2018-12-21 | 北京大华无线电仪器有限责任公司 | A kind of calibration method of high-power electronic load |
| CN112649672A (en) * | 2020-12-21 | 2021-04-13 | 北京大华无线电仪器有限责任公司 | Multi-module parallel electronic load |
| CN114564082A (en) * | 2022-01-23 | 2022-05-31 | 苏州浪潮智能科技有限公司 | Load card and load test system |
| CN114594822A (en) * | 2022-02-09 | 2022-06-07 | 广东中质检测技术有限公司 | High-power high-precision constant-current electronic load |
| CN114764259A (en) * | 2021-01-11 | 2022-07-19 | 台达电子企业管理（上海）有限公司 | Current control device and power conversion system using the same |
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Address after: Kolding road high tech Zone of Suzhou City, Jiangsu Province, No. 8 215163 Applicant after: Puyuan Jingdian Technology Co.,Ltd. Address before: Kolding road high tech Zone of Suzhou City, Jiangsu Province, No. 8 215163 Applicant before: RIGOL Technology Co.,Ltd. Address after: Kolding road high tech Zone of Suzhou City, Jiangsu Province, No. 8 215163 Applicant after: RIGOL Technology Co.,Ltd. Address before: Kolding road high tech Zone of Suzhou City, Jiangsu Province, No. 8 215163 Applicant before: SUZHOU RIGOL PRECISION ELECTRIC TECHNOLOGIES Co.,Ltd. |
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Application publication date: 20180828 |