CN115963888A - Constant current control device and constant current control method - Google Patents
Constant current control device and constant current control method Download PDFInfo
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Abstract
The invention discloses a constant current control device and a constant current control method, which comprise a floating constant current module, a gear switching anti-creeping compensation module and at least one floating constant current branch module which are mutually connected, wherein each module is connected with the input end of an object to be constant-current; the floating constant current module receives and processes the input initial signal, outputs a constant current sharing signal to the floating constant current branch module, and outputs a constant current signal in a preset numerical range to the object to be constant current; the gear switching anti-creeping compensation module generates a pressure difference relative to the output end of the floating constant-current module and outputs a voltage signal after voltage reduction; the floating constant current branch module generates a constant current branch signal which is superposed with the constant current signal and is input to an object to be constant current based on the input gear signal, the voltage signal and the constant current sharing signal. The device and the object to be subjected to constant current realize the constant current device with high precision and low electric leakage without isolation and complex devices, and realize multi-gear effect through simple device mirroring.
Description
Technical Field
The invention belongs to the field of circuit control, and particularly relates to a constant current control device and a constant current control method.
Background
Nonlinear elements and energy storage elements exist in a large number of electric equipment, so that the waveform of input alternating current is seriously distorted, and the input power factor of a power grid side is low. However, these electric devices have very high sensitivity to the supply current, and if the current fluctuation is large, the working accuracy of the electric devices will be reduced, even the electric devices will be damaged, so that the electric devices cannot work normally. In order to enable the power utilization input to meet the requirements, a constant current control circuit needs to be added at the front end of power utilization equipment and the rear end of power transmission equipment to convert and regulate initial signals given by the power transmission equipment.
At present, a constant current control circuit mainly comprises a comparison circuit and power output, meets general regulation requirements, and has the defects of fixed output, inconvenience in regulating maximum output current, incapability of realizing high-precision output current value, incapability of being used in occasions with high regulation proportion requirements, and easy existence of pressure difference when an object to be subjected to constant current is input.
Patent CN216290686U provides a wide input voltage constant current control circuit, which includes: the sampling circuit and the comparison circuit are connected with the input circuit and the output circuit in parallel, and the input circuit, the control circuit and the output circuit are connected in series; this scheme sets up sampling circuit and comparison circuit parallelly connected on input circuit and output circuit, and sets up control circuit on input circuit and output circuit with the mode of establishing ties to the form of interveneeing according to sampling circuit and comparison circuit's result regulates and control the electric current, thereby makes the electric current all can obtain effectual control in voltage variation within range, can't carry out the effective regulation and control of electric current when avoiding voltage to change on a large scale.
As described in the prior art, in some common constant current circuits, the adjusting circuit and the object to be constant-current need to have a common reference during the constant current process, and the object to be constant-current has higher requirements for the working environment. When a potential difference occurs between the adjusting circuit and an object to be constant-current, the whole constant-current circuit is slightly leaked, and therefore the constant-current precision is influenced.
In general, in order to reduce the requirement of the working environment of an object to be subjected to constant current, an isolation method is generally adopted to control an adjusting circuit to float so as to keep two pieces of direct no large potential difference, thereby eliminating the precision problem caused by the potential difference, but the method has high cost and depends on the isolation degree of an isolation power supply.
How to design a floating control constant current circuit solves the problems that the existing constant current control circuit is complex, has low precision and has leakage risk and needs to be solved urgently by technical personnel in the field.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the constant current control device and the constant current control method, the floating constant current module, the floating constant current branch module and the gear switching anti-creeping compensation module are arranged, so that the high-precision low-creepage constant current circuit is realized, and the multi-gear effect is realized through a simple circuit mirror image.
In a first aspect, the invention provides a constant current control device, which comprises a floating constant current module, a gear switching anti-creeping compensation module and at least one floating constant current branch module which are connected with each other, wherein each module is connected with an input end of an object to be constant-current;
the floating constant current module is used for receiving and processing an input initial signal, outputting a constant current sharing signal to the floating constant current branch module, and outputting a constant current signal in a preset numerical value range to an object to be subjected to constant current;
the gear switching anti-creeping compensation module is used for generating a voltage difference compared with the output end of the floating constant current module and outputting a voltage signal after voltage reduction;
and the floating constant current branch module generates a constant current branch signal which is superposed with the constant current signal and is input to an object to be constant current according to the input gear signal, the voltage signal and the constant current sharing signal.
Further, the floating constant current module comprises a feedback signal superposition compensation circuit, a first power amplifier circuit and a load potential feedback circuit;
the feedback signal superposition compensation circuit comprises a first operational amplifier, a second operational amplifier and a third operational amplifier, wherein the first operational amplifier is used for receiving an input initial signal and the voltage of the input end of an object to be constant-current fed back by the load potential feedback circuit and inputting a constant-current shared signal to the floating constant-current branch module and the first power amplifier circuit;
the first power amplifier circuit is used for processing a constant current shared signal of the feedback signal superposition compensation circuit and outputting a constant current signal, wherein the first power amplifier circuit comprises a second operational amplifier with a normal phase input end connected with the output end of the feedback signal superposition compensation circuit, a first MOS (metal oxide semiconductor) tube with a grid electrode connected with the output end of the second operational amplifier and a first resistor connected with the reverse phase input end of the second operational amplifier and the source electrode of the first MOS tube, and the drain electrode of the first MOS tube is connected with a positive power supply;
and the load potential feedback circuit is used for reading the voltage of the input end of the object to be constant-current and feeding back the voltage to a feedback pin of the first operational amplifier, wherein the load potential feedback circuit comprises a first follower.
Further, the feedback signal superposition compensation circuit receives input initial signals including initial constant current signals and reference signals;
the initial constant current signal is input into a positive phase input end of a first operational amplifier, and the reference signal is input into a negative phase input end of the first operational amplifier;
the feedback signal superposition compensation circuit subtracts the initial constant current signal from the reference signal and superposes the voltage of the input end of the object to be constant-current fed back by the load potential feedback circuit to output a constant current sharing signal.
Furthermore, the input end of the gear switching anti-creeping compensation module is connected with the first resistor, the input end of the load potential feedback circuit and the input end of the object to be constant-current;
the gear switching anti-creeping compensation module is formed by connecting a second follower, a diode and a third follower in series, and the output end of the diode is sequentially connected with a second resistor and a negative power supply (Vss).
Further, the pressure difference of the output end of the relative floating constant-current module is generated, and the method specifically comprises the following steps: and inputting the voltage of the input end of the object to be constant-current in real time, and reducing the voltage of the diode to obtain a voltage signal.
Furthermore, each floating constant-current branch module comprises a floating gear switching circuit and a second power amplifier circuit;
the floating gear switching circuit is used for receiving a gear signal, a constant current sharing signal and a voltage signal (REF) and outputting a branch adjusting signal;
and the second power amplifier circuit is used for adjusting the constant current branch signals input to the input end of the object to be constant current according to the branch adjusting signals output by the floating gear switching circuit.
Furthermore, the floating gear switching circuit comprises a photoelectric coupler and a third resistor (Rs), two ends of the third resistor are respectively connected with the output end of the feedback signal superposition compensation circuit and one end of the photoelectric coupler, the other end of the photoelectric coupler is connected with the output end of the gear switching anti-creeping compensation module, and the photoelectric coupler receives a gear signal to realize the on-off of two ends of the photoelectric coupler;
the input end and the output end of the second power amplifier circuit are respectively connected with one end of the photoelectric coupler and the object to be constant-current, the second power amplifier circuit comprises a third operational amplifier with a positive phase input end connected with one end of the photoelectric coupler, a second MOS (metal oxide semiconductor) tube with a grid electrode connected with the output end of the third operational amplifier and a fourth resistor connected with the reverse phase input end of the third operational amplifier and the source electrode of the second MOS tube, the fourth resistor is connected with the object to be constant-current, and the drain electrode of the second MOS tube is connected with a positive power supply (Vdd).
Further, photoelectric coupler includes light emitting component and light sensitive element, and light emitting component receives the gear signal to send light signal to light sensitive element, light sensitive element's one end and second power amplifier circuit connection, light sensitive element's the other end connect in gear switch anti-creeping compensation module's output.
Further, when the gear signal is a closing signal, a light emitting element in the photoelectric coupler sends a light signal to a photosensitive element, and the photosensitive element receives the light signal to conduct two ends, so that a second MOS (metal oxide semiconductor) tube of the second power amplifier circuit is in a forced reverse turn-off state; when the gear signal is a starting signal, the photosensitive element in the photoelectric coupler does not receive the light signal, two ends of the photosensitive element are disconnected, and the constant current sharing signal is connected to the second power discharge circuit.
In a second aspect, the present invention further provides a constant current control method, which includes the following steps:
setting a corresponding number of floating constant-current branch modules based on the control requirement;
determining a value of the initial signal;
inputting an initial signal to the floating constant-current module;
and adjusting the input gear signal according to the preset gear signal state to complete the floating control constant-current gear switching.
Compared with the prior art, the constant current control device and the constant current control method provided by the invention have the following technical effects:
(1) According to the invention, the floating constant-current module, the floating constant-current branch module and the gear switching anti-creeping compensation module are arranged, so that the high-precision low-creepage constant-current circuit is realized, and the multi-gear effect is realized through a simple circuit mirror image.
(2) The floating constant current module enables a target to be subjected to constant current to realize a constant current function within a dynamic range of a preset value range through the feedback signal superposition compensation circuit, the first power amplification circuit and the load potential feedback circuit.
(3) The gear switching anti-electric leakage compensation module is cooperated with the floating constant-current branch module, so that the risk of electric leakage caused by signal alternation is reduced.
(4) The effect of many gears can be realized to the stack of superficial constant current branch module. And the floating constant-current branch module cannot generate electric leakage due to signal alternation at any dynamic moment of the gear signal, so that the influence on the constant-current precision is caused.
Drawings
The above and other objects, features and advantages of exemplary embodiments of the present disclosure will become readily apparent from the following detailed description read in conjunction with the accompanying drawings. Several embodiments of the present disclosure are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar or corresponding parts and in which:
fig. 1 is a schematic diagram showing a constant current control device according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating a floating constant current module according to an embodiment of the invention;
FIG. 3 is a schematic diagram illustrating a shift-over anti-creep compensation module according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating a floating constant current branching module according to an embodiment of the invention;
fig. 5 is a flowchart illustrating a constant current control method according to an embodiment of the present invention.
Description of reference numerals: 1-floating constant current module, 11-feedback signal superposition compensation circuit, 111-first operational amplifier, 12-first power amplifier circuit, 121-second operational amplifier, 122-first MOS tube, 123-first resistor, 13-load potential feedback circuit, 131-first follower, 2-shift switching anti-creeping compensation module, 21-second follower, 22-diode, 23-third follower, 24-second resistor, 3-floating constant current branch module, 31-floating shift switching circuit, 311-photoelectric coupler, 312-third resistor, 32-second power amplifier circuit, 321-third operational amplifier, 322-second MOS tube, 323-fourth resistor, 4-object to be constant current.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.
It should be understood that, although the terms first, second, third, etc. may be used to describe \8230;, these \8230;, should not be limited to these terms in embodiments of the present invention. These terms are used only to distinguish between 8230; and vice versa. For example, without departing from the scope of embodiments of the present invention, a first of the methods may be used as a first of the methods for manufacturing a semiconductor device, and the method may be used as a second of the methods for manufacturing a semiconductor device, wherein the first of the methods may be used as a second of the methods for manufacturing a semiconductor device, and the second of the methods may be used as a second of the methods for manufacturing a semiconductor device.
It should be understood that the term "and/or" as used herein is merely a relationship that describes an associated object, meaning that three relationships may exist, e.g., a and/or B, may represent: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
The words "if", as used herein may be interpreted as "at \8230; \8230whenor" when 8230; \8230when or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrases "if determined" or "if detected (a stated condition or event)" may be interpreted as "when determined" or "in response to a determination" or "when detected (a stated condition or event)" or "in response to a detection (a stated condition or event)", depending on the context.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a good or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such good or apparatus. Without further limitation, an element defined by the phrases "comprising one of \8230;" does not exclude the presence of additional like elements in an article or device comprising the element.
The invention provides a constant current control device and a constant current control method, which realize a high-precision low-leakage constant current circuit by arranging a floating constant current module, a floating constant current branch module and a gear switching anti-leakage compensation module, and realize a multi-gear effect by simple circuit mirroring.
Alternative embodiments of the present invention are described in detail below with reference to the accompanying drawings.
The invention discloses a constant current control device, which comprises a floating constant current module 1, a gear switching anti-creeping compensation module 2 and at least one floating constant current branch module 3 which are mutually connected, wherein each module is connected with the input end of an object to be constant current 4;
the floating constant current module 1 is used for receiving and processing an input initial signal, outputting a constant current sharing signal to the floating constant current branch module 3, and outputting a constant current signal in a preset numerical value range to the object to be subjected to constant current 4;
the gear switching anti-creeping compensation module 2 is used for generating a voltage difference compared with the output end of the floating constant current module 1 and outputting a voltage-reduced voltage signal (such as OUT-REF in figure 1);
and the floating constant current branch module 3 is used for generating a constant current branch signal which is superposed with the constant current signal and is input to the object 4 to be constant current according to the input gear signal, the voltage signal and the constant current sharing signal.
The floating constant current module 1 in the constant current control device of the invention obtains an initial signal and considers the load potential (input end voltage) of the object 4 to be constant-current, thereby realizing the high-precision constant current function in the preset numerical value dynamic interval. The gear switching anti-leakage compensation module 2 reduces the risk of leakage under the signal alternating condition through the generated voltage drop. The floating constant-current branch modules 3 can realize repeated engraving and superposition in the constant-current control device, and realize the function of multi-stage gears based on the state change of initial signals and the input of gear signals of different floating constant-current branch modules 3.
The constant current control device is divided into three core parts: the device comprises a floating constant current module 1, a floating constant current branch module 3 and a gear switching anti-creeping compensation module 2.
As shown in fig. 2, the floating constant current module 1 includes a feedback signal superposition compensation circuit 11, a first power amplifier circuit 12 and a load potential feedback circuit 13;
the feedback signal superposition compensation circuit 11 comprises a first operational amplifier 111, preferably, the first operational amplifier 111 is an instrument amplifier, and is configured to receive an input initial signal and a voltage at an input end of the object to be constant-current 4, which is fed back by the load potential feedback circuit 13, and input a constant-current shared signal to the floating constant-current branch module 3 and the first power amplifier circuit 12;
the first power amplifier circuit 12 is configured to process the constant current shared signal of the feedback signal superposition compensation circuit 11 and output a constant current signal, where the first power amplifier circuit 12 includes a second operational amplifier 121 having a positive phase input end connected to the output end of the feedback signal superposition compensation circuit 11, a first MOS transistor 122 having a gate connected to the output end of the second operational amplifier 121, and a first resistor 123 connected to both the negative phase input end of the second operational amplifier 121 and the source of the first MOS transistor 122, and a drain of the first MOS transistor 122 is connected to a positive power supply (e.g., vdd in fig. 1 and 2);
the load potential feedback circuit 13 is configured to read a voltage at an input end of the object to be constant-current 4 (i.e., a voltage at an input end of the object to be constant-current 4), and feed back the voltage to a feedback pin of the first operational amplifier 111 in the feedback signal superposition compensation circuit 11, where the load potential feedback circuit includes a first follower 131.
The second operational amplifier 121 and the first MOS tube 122 form a follower, at this time, the gate voltage of the first MOS tube 122 changes with the load voltage of the object 4 to be constant-current, when the load voltage of the object 4 to be constant-current is larger, the gate voltage of the first MOS tube 122 increases, and conversely, the gate voltage decreases, so that the first MOS tube 122 is turned on and off according to different load voltages of the object 4 to be constant-current.
The feedback signal superposition compensation circuit 11 in fig. 1 and 2 receives input initial signals including an initial constant current signal and a reference signal; an initial constant current signal is input to a non-inverting input terminal of the first operational amplifier 111, and a reference signal is input to an inverting input terminal of the first operational amplifier 111; the feedback signal superposition compensation circuit 11 outputs a constant current sharing signal by subtracting the initial constant current signal from the reference signal and superposing the voltage at the input end of the object to be constant current 4 fed back by the load potential feedback circuit 13. In a practical application scenario, the voltage of the initial constant current signal is greater than the voltage of the reference signal.
In the floating constant current module 1, two signal inputs (an initial constant current signal and a reference signal) are provided on the left side of the first operational amplifier 111, the initial constant current signal is used for controlling a voltage value applied to the first resistor 123 so as to realize control of a constant current, the reference signal is a fixed voltage value, the voltage value is related to Vgs (threshold voltage) of the first MOS transistor 122 in the first power amplifier circuit 12, and the floating constant current module has the function that when the initial constant current signal is smaller than the reference signal, negative voltage can be generated at two ends of the Vgs of the first MOS transistor 122 so as to minimize Ids leakage of the first MOS transistor 122.
The feedback signal superposition compensation circuit 11 is, in fact, an instrumentation amplifier, and can realize the function of subtracting the inverted terminal signal from the input in-phase terminal signal and adding the compensation signal input on the Ref pin (feedback pin), and realize the superposition of the feedback signal through the characteristics of the instrumentation amplifier.
The first power amplifier circuit 12 is a typical operational amplifier diffusion current-spreading circuit, and the limited output power of the operational amplifier is expanded through the first MOS transistor 122, so that the upper limit of the output of the whole circuit is no longer determined by the characteristics of the operational amplifier (operational amplifier) itself but determined by the external first MOS transistor 122.
The load potential feedback circuit 13 is used for reading the load voltage value (input end voltage value) of the object 4 to be constant-current back to the feedback signal superposition compensation circuit 11, so that the load of the object 4 to be constant-current can float freely in the voltage range of Vdd-Vss without affecting the constant-current precision value.
The whole floating constant current module 1 has the function that an input initial constant current signal is subtracted from a reference signal to obtain a constant current shared signal which is input into a post-stage circuit, the constant current shared signal interval comprises a forced reverse pinch-off voltage of the first MOS tube 122 and a linear constant current interval, and a load potential feedback circuit 13 is used for reading back and compensating a load potential of an object 4 to be constant-current to the constant current shared signal in real time to realize a high-precision constant current function in a Vdd-Vss dynamic interval.
As shown in fig. 3, the input terminal of the shift switching leakage-prevention compensation module 2 is connected to the first resistor 123, the input terminal of the load potential feedback circuit 13, and the input terminal of the object 4 to be constant-current.
In fig. 3, the shift switching leakage-prevention compensation module 2 is connected in series by a second follower 21, a diode 22, and a third follower 23, and the output terminal of the diode 22 is connected to a second resistor 24 and a negative power supply (Vss) in this order.
The pressure difference of the output end of the relative floating constant-current module 1 is generated, and specifically: and reading the voltage input to the input end of the object 4 to be subjected to constant current in real time, reducing the voltage of the diode 22, and feeding back to obtain a voltage difference, wherein the voltage difference is a voltage signal after voltage reduction.
The function of the gear switching anti-creeping compensation module 2 is to read the load potential of the object 4 to be constant-current in real time, subtract a voltage drop value of one diode 22 and feed back the voltage drop value through a subsequent follower (third follower 23). The gear switching anti-creeping compensation module 2 is prepared for the following floating constant-current branch module 3, and can reduce the occurrence of creepage caused by the alternating of signals of a positive phase input end and a negative phase input end of an operational amplifier. (typically there will be a parasitic diode 22 between the non-inverting and inverting inputs of the op-amp to protect the chip input device from damage due to signals across it exceeding a maximum relative voltage, which is typically greater than the voltage drop provided by a schottky diode 22).
What plays an important role in the constant current control device of the present invention is the floating constant current branch modules 3, as shown in fig. 4, each floating constant current branch module 3 includes a floating gear switching circuit 31 and a second power amplifier circuit 32;
the floating gear switching circuit 31 is used for receiving a gear signal, a constant current sharing signal and a voltage signal, outputting a branch adjusting signal, wherein the branch adjusting signal is the constant current sharing signal or the voltage signal, and realizing the selection of the constant current sharing signal and the voltage signal through the gear signal;
and the second power amplifier circuit 32 is configured to process the branch adjusting signal output by the floating gear switching circuit 31, and generate a constant current branch signal which is input to the object to be constant-current in a manner of being superposed with the constant current signal.
The floating gear switching circuit 31 comprises a photoelectric coupler 311 and a third resistor 312, two ends of the third resistor 312 are respectively connected with the output end of the feedback signal superposition compensation circuit 11 and one end of the photoelectric coupler 311, the other end of the photoelectric coupler 311 is connected with the output end of the gear switching anti-creeping compensation module 2, and the photoelectric coupler 311 receives a gear signal to realize the on-off of two ends of the photoelectric coupler 311;
the second power amplifier circuit 32 is connected to the floating gear switching circuit 31, the floating constant current module 1, and the object 4 to be constant-current, the second power amplifier circuit 32 includes a third operational amplifier 321 whose positive phase input end is connected to one end of the photocoupler 311, a second MOS transistor 322 whose gate is connected to an output end of the third operational amplifier 321, and a fourth resistor 323 which is connected to both an inverting input end of the third operational amplifier 321 and a source of the second MOS transistor 322, the fourth resistor 323 is connected to the object 4 to be constant-current, and a drain of the second MOS transistor 322 is connected to a positive power supply (e.g., vdd in fig. 4). Preferably, the first MOS transistor 122 and the second MOS transistor 322 are both N-type MOS transistors.
The photoelectric coupler 311 includes a light emitting element and a photosensitive element, the light emitting element receives the gear signal to transmit a light signal to the photosensitive element, one end of the photosensitive element is connected to the second power amplifier circuit 32, and the other end of the photosensitive element is connected to the output end of the gear switching anti-creeping compensation module 2.
The floating constant current branch modules 3 are mainly controlled by changing the state of the gear signals and the number of the floating constant current branch modules 3, and a certain floating constant current branch module 3 is taken as an example: when the shift signal is the off signal, the light emitting element in the photoelectric coupler 311 sends an optical signal to the photosensitive element, and the photosensitive element receives the optical signal to turn on both ends, so that the second MOS transistor 322 of the second power amplifier circuit 32 is in a forced reverse off state; when the shift signal is the on signal, the photo sensor in the photo coupler 311 does not receive the optical signal, both ends thereof are disconnected, and the constant current sharing signal is connected to the second power amplifier circuit 32.
Can effectually let second MOS pipe 322 be in the reverse off-state of forcing when the gear signal is the close signal, because photoelectric coupler 311 both ends switch on when the gear signal is the close signal, OUT _ REF signal (voltage signal) is sent into in the second power amplifier circuit 32 of back stage, because OUT _ REF signal compares whole device output point voltage and has lacked a diode 22 dropout voltage, can't satisfy the constant current condition this moment (the grid voltage of second MOS pipe 322 is less than source voltage, second MOS pipe 322 does not switch on, this device can't absorb current, thereby Vgs at second MOS pipe 322 both ends can become the negative electricity and pinches off promptly). Meanwhile, since the voltage difference is changed in real time with the output voltage, and the voltage drop of at least one diode 22 is kept at any time, the floating gear switching circuit 31 does not affect the output constant current effect due to the fact that the positive phase input end and the negative phase input end of the operational amplifier (third operational amplifier 321) exceed the maximum voltage difference and leakage occurs no matter at any dynamic time.
When the shift signal is a start signal, the two ends of the photoelectric coupler 311 are disconnected, at this time, the third resistor 312 is connected to the output end of the feedback signal superposition compensation circuit, due to the action of the positive input end of the third operational amplifier 321, the current in the third resistor 312 is small, the voltage drop voltage of the third resistor 312 is negligible, the voltage input to the third operational amplifier 321 is equivalent to the voltage input to the second operational amplifier 121 (constant current shared signal), at this time, the second power amplifier circuit 32 in the floating constant current branch module 3 and the first power amplifier circuit 12 in the floating constant current module 1 become a shadow, and the constant currents at the two sides perform synchronous operation.
When the shift signal has a voltage, a diode 22 is disposed between the positive input terminal and the negative input terminal of the third operational amplifier 321, which protects the positive input terminal and the negative input terminal from a large voltage difference, which may damage the third operational amplifier 321. The voltage drop generated by the diode 22 can just fall within the voltage difference range, and when the following condition of the third operational amplifier 321 is destroyed, no extra current flows from the non-inverting input terminal to the inverting input terminal through the diode 22, so that a current signal which should not appear appears in the floating constant current branch module 3 does not appear. The output pin of the third operational amplifier 321 in the second power amplifier circuit 32 is only kept above the voltage value infinitely close to the negative power supply, thereby implementing the shutdown function of the gear. The voltage across the fourth resistor 323 will always remain between the voltage of the reference signal and the voltage of the initial constant current signal.
By the method, a plurality of floating constant-current branch modules can be repeatedly engraved, and the function of multi-level gears is realized by continuous superposition.
The floating meaning in the invention means that the object 4 to be constant-current can float at any potential point in a voltage interval from Vdd to Vss, and the fluctuation of the reference potential of the load (the object 4 to be constant-current) does not influence the constant-current effect. Meanwhile, the floating can be embodied on a multi-channel gear switching circuit (floating constant current branch module 3), the floating gear switching circuit 31 of the photoelectric coupler 311 floats in the control loop, and the gear signal and the control loop (the circuit of the floating constant current branch module 3 except the circuit on which the gear signal is located) are in a state of isolating two ends from each other.
In an actual application scenario, the voltage of the input end 2V of the object to be constant-current 4 is taken as an example, the initial constant-current signal is 2V, the reference signal is 0.5V, and the first MOS transistor 122 is in a conducting state, at this time, the voltage of the output end of the load potential feedback circuit 13 in the floating constant-current module 1 is 2V, and the voltage of the output end of the feedback signal superposition compensation circuit 11 is 3.5V. In the gear switching anticreeping compensation module 2, the voltage of the output end of the second follower 21 is 2V, the voltage drop of the diode 22 is 0.4V, and the voltage of the input end and the voltage of the output end of the third follower 23 are 1.6V. When the shift signal input by the photocoupler 311 in the floating constant current branch module 3 is a turn-off signal, due to the action of the photocoupler 311, the voltage at the positive input end of the third operational amplifier 321 is 1.6V, at this time, the voltage at the negative input end of the third operational amplifier 321 cannot be made to approach the voltage at the non-positive input end (operational amplifier following effect) by adjusting the second MOS transistor 322, at this time, the voltage at the negative input end is greater than that at the non-positive input end, the voltage at the output end of the third operational amplifier 321 is close to the negative power supply Vss, that is, the gate voltage of the second MOS transistor 322 approaches to the voltage of Vss, and in this state, at this time, the second MOS transistor 322 is always in the state of forced turn-off, that is, the current floating constant current branch module 3 is not connected. When the shift signal input by the photoelectric coupler 311 in the floating constant-current branch module 3 is a start signal, the photoelectric coupler 311 is in an off state, the voltage at the positive-phase input end of the third operational amplifier 321 is the voltage at the output end of the feedback signal superposition compensation circuit 11, and when the first MOS transistor 122 is in an on state, the second MOS transistor 322 is also in an on state.
The invention provides a constant current control device, which at least comprises the following advantages:
1. the requirement on the condition of the object to be subjected to constant current is not high, the adaptability is strong, for example, whether the object to be subjected to constant current is in a stable reference potential point or not is not concerned, the object to be subjected to constant current can be subjected to accurate constant current in a state that the reference potential point fluctuates frequently, and the method is suitable for occasions with high requirements on the stability of load current, such as precision instruments, medical equipment and the like.
2. The whole circuit is low in load realization, relatively simple in realization mode, free of excessive complex circuits or control systems, and low in cost and maintenance difficulty.
3. Stability and efficiency are considered, the complexity of the control circuit can be reduced, control can be realized only by a few simple signals, and the constant current circuit and the control circuit (control loop) are two systems which can not mutually interfere with each other.
As shown in fig. 5, the present invention further provides a constant current control method, which adopts the above constant current control device, and specifically includes the following steps:
setting a corresponding number of floating constant-current branch modules 3 based on control requirements, and constructing a constant-current control device comprising a floating constant-current module 1, a gear switching anti-creeping compensation module 2 and a floating constant-current branch module 3;
determining a value of the initial signal;
inputting an initial signal to the floating constant current module 1;
and adjusting the input gear signal according to the preset gear signal state to complete the floating control constant-current gear switching.
The constant current control device and the constant current control method provided by the invention have the following technical effects:
(1) According to the invention, the floating constant-current module, the floating constant-current branch module and the gear switching anti-creeping compensation module are arranged, so that a high-precision low-creepage constant-current circuit is realized, and a multi-gear effect is realized through a simple circuit mirror image.
(2) The floating constant-current module enables the object to be constant-current to realize the constant-current function within the dynamic range of the preset numerical range through the feedback signal superposition compensation circuit, the first power amplifier circuit and the load potential feedback circuit.
(3) The gear switching anti-electric leakage compensation module is cooperated with the floating constant-current branch module, so that the risk of electric leakage caused by signal alternation is reduced.
(4) The effect of many gears can be realized to the stack of superficial constant current branch module. And the floating constant-current branch module cannot generate electric leakage due to signal alternation at any dynamic moment of a gear signal, so that the influence on constant-current precision is caused.
Computer program code for carrying out operations for aspects of the present disclosure may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, smalltalk, C + +, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local Area Network (AN) or a Wide Area Network (WAN), or the connection may be made to AN external computer (for example, through the internet using AN internet service provider).
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
The units described in the embodiments of the present disclosure may be implemented by software or hardware. Where the name of an element does not in some cases constitute a limitation on the element itself.
The foregoing describes preferred embodiments of the present invention, and is intended to provide a clear and concise description of the spirit and scope of the invention, and not to limit the same, but to include all modifications, substitutions, and alterations falling within the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A constant current control device is used for providing constant current for an object to be constant-current, and is characterized by comprising a floating constant current module, a gear switching anti-creeping compensation module and at least one floating constant current branch module which are mutually connected, wherein each module is connected with the input end of the object to be constant-current;
the floating constant current module is used for receiving and processing an input initial signal, outputting a constant current sharing signal to the floating constant current branch module, and outputting a constant current signal in a preset numerical value range to an object to be subjected to constant current;
the gear switching anti-creeping compensation module is used for generating a voltage difference compared with the output end of the floating constant current module and outputting a voltage signal after voltage reduction;
and the floating constant current branch module is used for generating a constant current branch signal which is superposed with the constant current signal and is input to an object to be constant-current according to the input gear signal, the voltage signal and the constant current sharing signal.
2. The constant-current control device of claim 1, wherein the floating constant-current module comprises a feedback signal superposition compensation circuit, a first power amplifier circuit and a load potential feedback circuit;
the feedback signal superposition compensation circuit comprises a first operational amplifier, a second operational amplifier and a third operational amplifier, wherein the first operational amplifier is used for receiving an input initial signal and the voltage of the input end of a to-be-constant current object fed back by the load potential feedback circuit and inputting a constant current shared signal to the floating constant current branch module and the first power amplification circuit;
the first power amplifier circuit is used for processing a constant current shared signal of the feedback signal superposition compensation circuit and outputting a constant current signal, wherein the first power amplifier circuit comprises a second operational amplifier with a positive phase input end connected with the output end of the feedback signal superposition compensation circuit, a first MOS (metal oxide semiconductor) tube with a grid electrode connected with the output end of the second operational amplifier and a first resistor connected with the negative phase input end of the second operational amplifier and the source electrode of the first MOS tube, and the drain electrode of the first MOS tube is connected with a positive power supply;
and the load potential feedback circuit is used for reading the voltage of the input end of the object to be constant-current and feeding back the voltage to a feedback pin of the first operational amplifier, wherein the load potential feedback circuit comprises a first follower.
3. The constant current control device of claim 2, wherein the feedback signal superposition compensation circuit receives input initial signals including an initial constant current signal and a reference signal;
the initial constant current signal is input into a positive phase input end of a first operational amplifier, and the reference signal is input into a negative phase input end of the first operational amplifier;
the feedback signal superposition compensation circuit subtracts the initial constant current signal from the reference signal and superposes the voltage of the input end of the object to be constant-current fed back by the load potential feedback circuit to output a constant current sharing signal.
4. The constant-current control device as claimed in claim 2, wherein the input terminal of the shift switching anti-creeping compensation module is connected with the first resistor, the input terminal of the load potential feedback circuit and the input terminal of the object to be constant-current;
the gear switching anti-creeping compensation module is formed by connecting a second follower, a diode and a third follower in series, and the output end of the diode is sequentially connected with a second resistor and a negative power supply.
5. The constant current control device of claim 4, wherein a differential pressure is generated with respect to the output of the floating constant current module, specifically: and inputting the voltage of the input end of the object to be subjected to constant current in real time, and reducing the voltage of the diode to obtain a voltage signal.
6. The constant-current control device of claim 2, wherein each floating constant-current branch module comprises a floating gear switching circuit and a second power amplifier circuit;
the floating gear switching circuit is used for receiving a gear signal, a constant current sharing signal and a voltage signal and outputting a branch adjusting signal;
and the second power amplifier circuit is used for adjusting the constant current branch signals input to the input end of the object to be constant current according to the branch adjusting signals output by the floating gear switching circuit.
7. The constant-current control device as claimed in claim 6, wherein the floating gear switching circuit comprises a photocoupler and a third resistor, two ends of the third resistor are respectively connected with the output end of the feedback signal superposition compensation circuit and one end of the photocoupler, the other end of the photocoupler is connected with the output end of the gear switching anti-creeping compensation module, and the photocoupler receives the gear signal to realize the on-off of the two ends;
the input end and the output end of the second power amplifier circuit are respectively connected with one end of the photoelectric coupler and the object to be constant-current, the second power amplifier circuit comprises a third operational amplifier with a positive phase input end connected with one end of the photoelectric coupler, a second MOS tube with a grid electrode connected with the output end of the third operational amplifier and a fourth resistor connected with the reverse phase input end of the third operational amplifier and the source electrode of the second MOS tube, the fourth resistor is connected with the object to be constant-current, and the drain electrode of the second MOS tube is connected with the positive power supply.
8. The constant current control device according to claim 7, wherein the photo coupler includes a light emitting element and a photo sensor, the light emitting element receives the shift signal to transmit the light signal to the photo sensor, one end of the photo sensor is connected to the second power amplifier circuit, and the other end of the photo sensor is connected to an output terminal of the shift switching leakage-preventing compensation module.
9. The constant current control device according to claim 8, wherein when the shift signal is an off signal, the light emitting element in the photocoupler sends a light signal to the light sensitive element, and the light sensitive element receives the light signal to turn on both ends, which makes the second MOS transistor of the second power amplifier circuit in a forced reverse off state; when the gear signal is a starting signal, the photosensitive element in the photoelectric coupler does not receive the light signal, two ends of the photosensitive element are disconnected, and the constant current sharing signal is connected to the second power discharge circuit.
10. A constant current control method, characterized in that, using the constant current control device according to any one of claims 1 to 9, specifically comprising the steps of:
setting a corresponding number of floating constant-current branch modules based on the control requirement;
determining a value of the initial signal;
inputting an initial signal to the floating constant-current module;
and adjusting the input gear signal according to the preset gear signal state to complete the floating control constant-current gear switching.
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