CN115963888B - 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, comprising a floating constant current module, a gear switching anti-leakage compensation module and at least one floating constant current branch module which are connected with each other, 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 with a preset numerical range to an object to be constant current; the gear switching anti-leakage compensation module generates a differential pressure of the output end of the relative 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 overlapped 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 constant current realize the constant current device with high precision and low electric leakage without isolation and complex devices, and realize the multi-gear effect through simple device mirror image.
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
In a large number of electric devices, nonlinear elements and energy storage elements exist, so that input alternating current waveforms are severely distorted, and the input power factor at the power grid side is low. However, these consumers have very high sensitivity to the supply current, and if the current fluctuates greatly, the working accuracy of the consumers is reduced, and even the consumers are damaged, so that the consumers cannot work normally. In order to enable the power input to meet the requirements, a constant current control circuit is added at the front end of the electric equipment and the rear end of the electric equipment, and conversion adjustment is carried out on an initial signal fed by the electric equipment.
At present, the constant current control circuit mainly comprises a comparison circuit and power output, meets the general regulation requirement, has the defects of fixed output, inconvenient regulation of maximum output current, incapability of realizing high-precision output current value, incapability of being used in occasions with high regulation proportion requirement, and easy existence of pressure difference when an object to be constant current is input.
Patent CN216290686U, for example, presents a wide input voltage constant current control circuit comprising: the device comprises an input circuit, a sampling circuit, a comparison circuit, a control circuit and an output circuit, wherein 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; according to the scheme, the sampling circuit and the comparison circuit are arranged on the input circuit and the output circuit in parallel, and the control circuit is arranged on the input circuit and the output circuit in a serial connection mode, so that current is regulated and controlled in an intervening mode according to the results of the sampling circuit and the comparison circuit, the current can be effectively controlled within a voltage change range, and the problem that the current cannot be effectively regulated and controlled when the voltage is changed in a large range is avoided.
In the prior art, in the common constant current circuits, the adjusting circuit and the object to be constant current all need to have a common reference in the constant current process, and the object to be constant current has higher working environment requirement. When a potential difference occurs between the adjusting circuit and the object to be constant-current, the whole constant-current circuit is slightly leaked, so that the constant-current precision is affected.
In order to reduce the requirement of the working environment of the object to be constant-current, the method of floating the adjusting circuit is generally adopted to control so as to keep two direct and non-great potential differences at any time, thereby eliminating the precision problem caused by the potential differences, but the method has high cost and is very dependent on the isolation degree of an isolated power supply.
How to design a floating control constant current circuit solves the problems that the existing constant current control circuit is complex, low in precision and has leakage risk and is needed to be solved by the technicians 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, which realize a high-precision low-leakage constant current circuit by arranging the floating constant current module, the floating constant current branch module and the gear switching anti-leakage compensation module, and realize a multi-gear effect by simple circuit mirroring.
In a first aspect, the invention provides a constant current control device, which comprises a floating constant current module, a gear switching anti-leakage 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 the input initial signal, outputting a constant current sharing signal to the floating constant current branch module and outputting a constant current signal with a preset numerical range to an object to be constant current;
the gear switching anti-leakage compensation module is used for generating a voltage difference at 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 overlapped with the constant current signal and is input to the 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 floating constant current branch module and a first power amplifier circuit, wherein the first operational amplifier is used for receiving an input initial signal and the voltage of an input end of an object to be constant current fed back by the load potential feedback circuit, and inputting a constant current sharing 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 sharing 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, a first MOS (metal oxide semiconductor) tube and a first resistor, the second operational amplifier is connected with the output end of the feedback signal superposition compensation circuit, the first MOS tube is connected with the grid electrode of the first MOS tube, the first resistor is connected with the inverting 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 the 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 an input initial signal comprising an initial constant current signal and a reference signal;
an initial constant current signal is input to a non-inverting input end of the first operational amplifier, and a reference signal is input to an inverting input end of the first operational amplifier;
the feedback signal superposition compensation circuit outputs a constant current sharing signal by subtracting the initial constant current signal from the reference signal and superposing the voltage of the input end of the object to be constant current fed back by the load potential feedback circuit.
Further, the input end of the gear switching anti-leakage compensation module is connected with the input end of 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-leakage compensation module is connected in series by a second follower, a diode and a third follower, and the output end of the diode is sequentially connected with a second resistor and a negative power supply (Vss).
Further, a differential pressure is generated at the output end of the relative floating constant current module, specifically: and inputting the voltage of the input end of the object to be constant-current in real time, and subtracting the voltage of the diode to obtain a voltage signal.
Further, each floating constant current branch module comprises a floating position switching circuit and a second power amplifier circuit;
a neutral shift circuit for receiving a shift signal, a constant current sharing signal, and a voltage signal (REF), and outputting a branch adjustment signal;
and the second power amplifier circuit is used for adjusting the constant current branch signal input into the input end of the object to be constant current according to the branch adjusting signal output to the floating position switching circuit.
Further, the neutral position switching circuit comprises a photoelectric coupler and a third resistor (Rs), wherein 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 position switching anti-leakage compensation module, and the photoelectric coupler receives a gear position signal so as 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 an object to be constant current, the second power amplifier circuit comprises a third operational amplifier, a second MOS tube and a fourth resistor, the positive input end of the third operational amplifier is connected with one end of the photoelectric coupler, the grid electrode of the second MOS tube is connected with the output end of the third operational amplifier, the fourth resistor is connected with the inverting 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, the photoelectric coupler comprises a light-emitting element and a photosensitive element, the light-emitting element receives a gear signal to send an optical signal to the photosensitive element, one end of the photosensitive element is connected with the second power amplifier circuit, and the other end of the photosensitive element is connected with the output end of the gear switching anti-leakage compensation module.
Further, when the gear signal is a closing signal, the light emitting element in the photoelectric coupler sends an optical signal to the photosensitive element, and the photosensitive element receives the optical signal to conduct two ends, so that the second MOS tube of the second power amplifier circuit is in a forced reverse closing state; when the gear signal is an opening signal, the photosensitive element in the photoelectric coupler does not receive the optical signal, two ends of the photosensitive element are disconnected, and the constant current sharing signal is connected to the second power amplifier circuit.
In a second aspect, the present invention further provides a constant current control method, which adopts the constant current control device, and specifically includes the following steps:
based on control requirements, a corresponding number of floating constant current branch modules are arranged;
determining a value of the initial signal;
inputting an initial signal to the floating constant current module;
and adjusting an input gear signal according to the state of a preset gear signal to finish 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-leakage compensation module are arranged, so that a high-precision low-leakage 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 in 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-leakage compensation module is cooperated with the floating constant current branch module, so that the risk of leakage caused by signal alternation is reduced.
(4) The floating constant current branch modules are overlapped, so that the effect of multiple gears can be realized. And the floating constant current branch module can not generate electric leakage condition due to signal alternation at any dynamic moment of gear signals, thereby causing influence on constant current precision.
Drawings
The above, as well as additional purposes, features, and advantages of exemplary embodiments of the present disclosure will become readily apparent from the following detailed description when 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 apparatus 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 present invention;
FIG. 3 is a schematic diagram illustrating a gear shift anti-creep compensation module according to an embodiment of the present invention;
fig. 4 is a schematic diagram showing a floating constant current branching module according to an embodiment of the present invention;
fig. 5 is a flowchart showing a constant current control method according to an embodiment of the present invention.
Reference numerals illustrate: the device comprises a 1-floating constant current module, an 11-feedback signal superposition compensation circuit, a 111-first operational amplifier, a 12-first power amplifier circuit, a 121-second operational amplifier, a 122-first MOS tube, a 123-first resistor, a 13-load potential feedback circuit, a 131-first follower, a 2-gear switching anti-leakage compensation module, a 21-second follower, a 22-diode, a 23-third follower, a 24-second resistor, a 3-floating constant current branch module, a 31-floating neutral position switching circuit, a 311-photoelectric coupler, a 312-third resistor, a 32-second power amplifier circuit, a 321-third operational amplifier, a 322-second MOS tube, a 323-fourth resistor and a 4-object to be constant current.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the 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 this application 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, the "plurality" generally includes at least two.
It should be understood that although the terms first, second, third, etc. may be used to describe … … in embodiments of the present invention, these … … should not be limited to these terms. These terms are only used to distinguish … …. For example, the first … … may also be referred to as the second … …, and similarly the second … … may also be referred to as the first … …, without departing from the scope of embodiments of the present invention.
It should be understood that the term "and/or" as used herein is merely one relationship describing the association of the associated objects, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
The words "if", as used herein, may be interpreted as "at … …" or "at … …" or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrase "if determined" or "if detected (stated condition or event)" may be interpreted as "when determined" or "in response to determination" or "when detected (stated condition or event)" or "in response to detection (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 product 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 product or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a commodity or device comprising such 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 will be 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-leakage compensation module 2 and at least one floating constant current branch module 3 which are connected with each other, wherein each module is connected with the input end of an object 4 to be constant current;
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 with a preset numerical range to the object to be constant current 4;
the gear switching anti-leakage compensation module 2 is used for generating a voltage difference at the output end of the floating constant current module 1 and outputting a voltage signal after voltage reduction (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 overlapped with the constant current signal and is input into the object 4 to be constant current according to the input gear signal, the voltage signal and the constant current sharing signal.
In the constant current control device, the floating constant current module 1 acquires 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 a preset value dynamic interval. The gear switching anti-leakage compensation module 2 reduces the risk of leakage under the condition of signal alternation through the generated voltage drop. The floating constant current branch modules 3 can realize the repeated engraving and superposition in the constant current control device, and realize the function of multi-stage gear based on the state change of initial signals and the gear signals input to 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-leakage compensation module 2.
The floating constant current module 1 comprises a feedback signal superposition compensation circuit 11, a first power amplifier circuit 12 and a load potential feedback circuit 13 as shown in fig. 2;
the feedback signal superposition compensation circuit 11 comprises a first operational amplifier 111, preferably, the first operational amplifier 111 is an instrumentation amplifier, and is used for receiving an input initial signal and the voltage of the input end of the object 4 to be constant current fed back by the load potential feedback circuit 13, and inputting a constant current sharing 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 with a positive input end connected to an output end of the feedback signal superposition compensation circuit 11, a first MOS transistor 122 with a gate connected to an output end of the second operational amplifier 121, and a first resistor 123 connected to an inverting input end of the second operational amplifier 121 and a source of the first MOS transistor 122, and a drain of the first MOS transistor 122 is connected to a positive power supply (such as 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., an input end voltage 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 feedback pin includes the 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 to be constant current 4, when the load voltage of the object to be constant current 4 is larger, the gate voltage of the first MOS tube 122 increases, and conversely decreases, so that the first MOS tube 122 is turned on and off according to the load voltage of the object to be constant current 4.
The feedback signal superposition compensation circuit 11 in fig. 1 and 2 receives an input initial signal 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 of the input end of the object 4 to be constant current fed back by the load potential feedback circuit 13. In an actual application scenario, the voltage of the initial constant current signal is greater than the voltage of the reference signal.
The floating constant current module 1, the left side of the first operational amplifier 111 is two signal inputs (an initial constant current signal and a reference signal), the initial constant current signal is used for controlling a voltage value applied to the first resistor 123 so as to realize the control of the 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 when the initial constant current signal is smaller than the reference signal, negative pressure can be generated at two ends of Vgs of the first MOS transistor 122 so as to enable Ids leakage of the first MOS transistor 122 to be minimized.
The feedback signal superposition compensation circuit 11 is actually an instrumentation amplifier, which can subtract the signal of the reverse end from the signal of the in-phase end and add the compensation signal input on the Ref pin (feedback pin), and realize the function of feedback signal superposition through the characteristics of the instrumentation amplifier.
The first power amplifier circuit 12 is a typical operational amplifier diffusion and current expansion circuit, and expands the limited operational amplifier output power through the first MOS tube 122, so that the upper output limit of the whole circuit is not determined by the characteristics of the operational amplifier (operational amplifier) but by the external first MOS tube 122.
The load potential feedback circuit 13 reads and sends 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 freely float within the voltage range of Vdd-Vss without affecting the constant-current precision value.
The whole floating constant current module 1 has the function of subtracting the input initial constant current signal from the reference signal to obtain a constant current sharing signal input into a later-stage circuit, wherein the constant current sharing signal interval comprises the forced reverse pinch-off voltage of the first MOS tube 122 and a linear constant current interval, and the load potential of the object 4 to be constant current is read back and compensated to the constant current sharing signal in real time through a load potential feedback circuit 13, so that the high-precision constant current function in the dynamic interval of Vdd-Vss is realized.
As shown in fig. 3, the input terminal of the gear shift anticreep compensation module 2 is connected with 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 gear shift anti-leakage compensation module 2 is connected in series by a second follower 21, a diode 22 and a third follower 23, and the output end of the diode 22 is connected with a second resistor 24 and a negative power supply (Vss) in turn.
The differential pressure of the output end of the relative floating constant current module 1 is generated, specifically: the voltage input to the input end of the object 4 to be constant-current is read in real time, the voltage of the diode 22 is reduced, and the voltage difference is obtained through feedback, and the voltage difference is a voltage signal after voltage reduction.
The gear switching anti-leakage compensation module 2 is used for reading the load potential of the object 4 to be constant-current in real time, subtracting the voltage drop value of one diode 22 and feeding back the voltage drop value through a follow-up follower (a third follower 23). The gear switching anti-leakage compensation module 2 is used for preparing a rear floating constant current branch module 3, and can reduce the occurrence of leakage caused by signal alternation of a positive phase input end and a negative phase input end of an operational amplifier. (typically, there is a parasitic diode 22 between the inverting and inverting inputs of the op-amp to protect the chip input device from damage due to the signal at the two terminals exceeding the maximum relative voltage, and this voltage difference is typically greater than the voltage drop provided by a schottky diode 22).
The floating constant current branch modules 3 play an important role in the constant current control device, and as shown in fig. 4, each floating constant current branch module 3 comprises a floating position switching circuit 31 and a second power amplifier circuit 32;
a neutral position switching circuit 31 for receiving a gear signal, a constant current sharing signal, and a voltage signal, outputting a branch adjustment signal, the branch adjustment signal being a constant current sharing signal or a voltage signal, and realizing selection of the constant current sharing signal and the voltage signal by the gear signal;
and a second power amplifier circuit 32 for processing the branch adjustment signal output from the floating position switching circuit 31 to generate a constant current branch signal which is superimposed with the constant current signal and input to the object to be constant current.
The neutral position switching circuit 31 comprises a photoelectric coupler 311 and a third resistor 312, wherein 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 position switching anti-leakage compensation module 2, and the photoelectric coupler 311 receives a gear position signal to realize the on-off of two ends of the gear position signal;
the second power amplifier 32 is connected to the floating neutral position switching circuit 31, the floating constant current module 1 and the object 4 to be constant current, the second power amplifier 32 includes a third operational amplifier 321 with a positive input end connected to one end of the photocoupler 311, a second MOS transistor 322 with a gate connected to an output end of the third operational amplifier 321, and a fourth resistor 323 connected to an inverting input end of the third operational amplifier 321 and a source of the second MOS transistor 322, where 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 (as in Vdd in fig. 4). Preferably, the first MOS transistor 122 and the second MOS transistor 322 are both N-type MOS transistors.
The photocoupler 311 includes a light emitting element and a photosensitive element, the light emitting element receives a gear signal to send an optical signal to the photosensitive element, one end of the photosensitive element is connected with 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-leakage compensation module 2.
The control of the floating constant current branch module 3 is mainly performed through state transformation of gear signals and the number of the floating constant current branch modules 3, taking a certain floating constant current branch module 3 as an example: when the gear signal is a closing 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 conduct two ends, so that the second MOS tube 322 of the second power amplifier circuit 32 is in a forced reverse closing state; when the gear signal is an on signal, the photosensitive element in the photocoupler 311 does not receive the optical signal, two ends of the photosensitive element are disconnected, and the constant current sharing signal is connected to the second power amplifier circuit 32.
When the gear signal is the off signal, the second MOS transistor 322 can be effectively in the forced reverse off state, because the two ends of the photocoupler 311 are turned on when the gear signal is the off signal, the out_ref signal (voltage signal) is sent to the second power amplifier circuit 32 at the rear stage, and the out_ref signal is one diode 22 voltage drop less than the output point voltage of the whole device, so that the constant current condition cannot be satisfied (the gate voltage of the second MOS transistor 322 is less than the source voltage, the second MOS transistor 322 is not turned on, and the device cannot absorb the current, i.e., vgs at the two ends of the second MOS transistor 322 becomes negative and is cut off). Meanwhile, since the voltage difference is changed with the output voltage in real time, and the voltage drop voltage of one diode 22 is kept at any time, the floating-position switching circuit 31 cannot influence the output constant current effect due to the fact that the non-inverting input terminal and the inverting input terminal of the operational amplifier (the third operational amplifier 321) exceed the maximum voltage difference at any dynamic time.
When the gear signal is an on signal, two ends of the photocoupler 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 effect of the normal phase input end of the third operational amplifier 321, the current in the third resistor 312 is smaller, the voltage drop of the third resistor 312 is negligible, the voltage input into the third operational amplifier 321 corresponds to the voltage input into the second operational amplifier 121 (constant current sharing signal), at this time, the second power amplifier 32 in the floating constant current branch module 3 will become shadow with the first power amplifier 12 in the floating constant current module 1, and the constant currents at two sides will perform synchronous operation.
When the gear signal has a voltage, a diode 22 is arranged between the non-inverting input terminal and the inverting input terminal of the third operational amplifier 321, which protects the non-inverting input terminal and the inverting input terminal from a large voltage difference, resulting in damage to the third operational amplifier 321. The voltage drop generated by the diode 22 may fall just within this voltage difference range, and when the following condition of the third operational amplifier 321 is broken, no additional current flows from the non-inverting input terminal to the inverting input terminal through the diode 22, so that the floating constant current branching module 3 generates a current signal that should not occur. The output pin of the third operational amplifier 321 in the second power amplifier circuit 32 is only kept above the voltage value of the infinitely close negative power supply, thereby realizing the closing 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 mode, a plurality of floating constant current branch modules can be etched repeatedly, and the function of multi-stage gears is realized through continuous superposition.
The floating meaning in the invention means that the object 4 to be constant current can float at any potential point in the voltage range of Vdd-Vss, and the reference potential fluctuation of the load (the object 4 to be constant current) does not influence the effect of constant current. Meanwhile, the floating can also be embodied on a multi-path gear switching circuit (a floating constant current branch module 3), the floating gear switching circuit 31 of the photoelectric coupler 311 floats in a control loop, and a gear signal and the control loop (circuits of the floating constant current branch module 3 except for circuits on which the gear signal is located) are in a state of being isolated at two ends and do not interfere with each other.
In an actual application scenario, the voltage of 2V at the input end of the object 4 to be constant-current is taken as an example, the initial constant-current signal is 2V, the reference signal is 0.5V, the first MOS tube 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 anti-leakage 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 gear signal input by the photocoupler 311 in the floating constant current branch module 3 is a closing signal, the voltage of the normal phase input end of the third operational amplifier 321 is 1.6V due to the effect of the photocoupler 311, the voltage of the reverse phase input end of the third operational amplifier 321 cannot approach the voltage of the normal phase input end (operational amplifier following effect) by adjusting the second MOS transistor 322, the voltage of the reverse phase input end is larger than the voltage of the normal phase input end, the voltage of the output end of the third operational amplifier 321 approaches the negative power supply Vss, that is, the voltage of the gate electrode of the second MOS transistor 322 approaches to Vss, and in this state, the second MOS transistor 322 is always in a forced closing state, that is, the current floating constant current branch module 3 is not connected. When the gear signal input by the photocoupler 311 in the floating constant current branch module 3 is an on signal, the photocoupler 311 is in an off state, the voltage of the non-inverting input terminal of the third operational amplifier 321 is the voltage of the output terminal 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 constant current control device provided by the invention at least comprises the following advantages:
1. the condition requirement on the object to be constant-current is not high, the adaptability is strong, for example, whether the object to be constant-current is positioned at a stable reference potential point is not concerned, the object to be constant-current can be precisely constant in a state that the reference potential point is frequently fluctuated, and the object to be constant-current is suitable for occasions with high requirements on load current stability, such as precise instruments, medical equipment and the like.
2. The whole circuit has low implementation load, the implementation mode is relatively simple, excessive complex circuits or control systems are not needed, and the cost and the maintenance difficulty are reduced.
3. The stability and the efficiency are both considered, the complexity of the control circuit can be reduced, the control can be realized only by a few simple signals, and the constant current circuit and the control circuit (control loop) are two sets of systems which can not interfere with each other.
As shown in fig. 5, the present invention further provides a constant current control method, which adopts the constant current control device, and specifically includes the following steps:
based on control requirements, a corresponding number of floating constant current branch modules 3 are arranged, and a constant current control device comprising a floating constant current module 1, a gear switching anti-leakage compensation module 2 and the floating constant current branch modules 3 is constructed;
determining a value of the initial signal;
inputting an initial signal to the floating constant current module 1;
and adjusting an input gear signal according to the state of a preset gear signal to finish 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-leakage compensation module are arranged, so that a high-precision low-leakage 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 in 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-leakage compensation module is cooperated with the floating constant current branch module, so that the risk of leakage caused by signal alternation is reduced.
(4) The floating constant current branch modules are overlapped, so that the effect of multiple gears can be realized. And the floating constant current branch module can not generate electric leakage condition due to signal alternation at any dynamic moment of gear signals, thereby causing influence on constant current precision.
Computer program code for carrying out operations of the present disclosure may be written in 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 can be connected to the user's computer through any kind of network, including a local Area Network (AN) or a Wide Area Network (WAN), or can be connected to AN external computer (for example, through the Internet using AN Internet service provider).
The flowcharts 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 which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
The units involved in the embodiments of the present disclosure may be implemented by means of software, or may be implemented by means of hardware. Wherein the names of the units do not constitute a limitation of the units themselves in some cases.
The foregoing description of the preferred embodiments of the present invention has been presented for purposes of clarity and understanding, and is not intended to limit the invention to the particular embodiments disclosed, but is intended to cover all modifications, alternatives, and improvements within the spirit and scope of the invention as outlined by the appended claims.
Claims (10)
1. The 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-leakage compensation module and at least one floating constant current branch module which are connected with each other, 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 the input initial signal, outputting a constant current sharing signal to the floating constant current branch module and outputting a constant current signal with a preset numerical range to an object to be constant current;
the gear switching anti-leakage compensation module is used for generating a voltage difference at the output end of the floating constant current module and outputting a voltage signal after voltage reduction;
the floating constant current branch module is used for generating a constant current branch signal which is overlapped with the constant current signal and is input into 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 according to 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 floating constant current branch module and a first power amplifier circuit, wherein the first operational amplifier is used for receiving an input initial signal and the voltage of an input end of an object to be constant current fed back by the load potential feedback circuit, and inputting a constant current sharing 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 sharing 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, a first MOS (metal oxide semiconductor) tube and a first resistor, the second operational amplifier is connected with the output end of the feedback signal superposition compensation circuit, the first MOS tube is connected with the grid electrode of the first MOS tube, the first resistor is connected with the inverting 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 the feedback pin of the first operational amplifier, wherein the load potential feedback circuit comprises a first follower.
3. The constant current control device according to claim 2, wherein the feedback signal superposition compensation circuit receives an input initial signal including an initial constant current signal and a reference signal;
an initial constant current signal is input to a non-inverting input end of the first operational amplifier, and a reference signal is input to an inverting input end of the first operational amplifier;
the feedback signal superposition compensation circuit outputs a constant current sharing signal by subtracting the initial constant current signal from the reference signal and superposing the voltage of the input end of the object to be constant current fed back by the load potential feedback circuit.
4. The constant current control device according to claim 2, wherein an input end of the gear switching anti-leakage compensation module is connected with an input end of the first resistor, the load potential feedback circuit and an input end of the object to be constant current;
the gear switching anti-leakage compensation module is connected in series by a second follower, a diode and a third follower, 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 according to claim 4, wherein a differential pressure is generated at the output end of the relative floating constant current module, specifically: and inputting the voltage of the input end of the object to be constant-current in real time, and subtracting the voltage of the diode to obtain a voltage signal.
6. The constant current control device according to claim 2, wherein each floating constant current branch module includes a floating bit switching circuit and a second power amplifier circuit;
the neutral position switching circuit is used for receiving a gear signal, a constant current sharing signal and a voltage signal and outputting a branch circuit adjusting signal;
and the second power amplifier circuit is used for adjusting the constant current branch signal input into the input end of the object to be constant current according to the branch adjusting signal output to the floating position switching circuit.
7. The constant current control device according to claim 6, wherein the neutral position switching circuit comprises a photoelectric coupler and a third resistor, both 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 position switching anti-leakage compensation module, and the photoelectric coupler receives the gear position signal to realize the on-off of both 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 an object to be constant current, the second power amplifier circuit comprises a third operational amplifier, a second MOS tube and a fourth resistor, the positive input end of the third operational amplifier is connected with one end of the photoelectric coupler, the grid electrode of the second MOS tube is connected with the output end of the third operational amplifier, the fourth resistor is connected with the inverting 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.
8. The constant current control device according to claim 7, wherein the photocoupler includes a light emitting element and a photosensitive element, the light emitting element receives a shift signal to transmit an optical signal to the photosensitive element, one end of the photosensitive element is connected to the second power amplifier circuit, and the other end of the photosensitive element is connected to an output end of the shift switching anti-leakage compensation module.
9. The constant current control device according to claim 8, wherein when the gear signal is a turn-off signal, the light emitting element in the photocoupler sends an optical signal to the photosensitive element, and the photosensitive element receives the optical signal to turn on two ends, so that the second MOS transistor of the second power amplifier circuit is in a forced reverse turn-off state; when the gear signal is an opening signal, the photosensitive element in the photoelectric coupler does not receive the optical signal, two ends of the photosensitive element are disconnected, and the constant current sharing signal is connected to the second power amplifier circuit.
10. A constant current control method, characterized in that the constant current control device according to any one of claims 1 to 9 is adopted, comprising the following steps:
based on control requirements, a corresponding number of floating constant current branch modules are arranged;
determining a value of the initial signal;
inputting an initial signal to the floating constant current module;
and adjusting an input gear signal according to the state of a preset gear signal to finish the floating control constant-current gear switching.
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