Electromagnetic coil driving circuit structure with constant current

Abstract

The utility model relates to the technical field of circuits, in particular to a constant-current electromagnetic coil driving circuit structure, which is characterized by comprising an input control signal, a first circuit module, a second circuit module, a third circuit module and a pull-up voltage source which are connected in sequence, the second circuit module comprises a PWM comparator, a first hysteresis resistor, a hysteresis reference voltage source, a hysteresis comparator, a current-limiting resistor and an N-MOS which are connected in sequence, the PWM comparator is connected with the first circuit module, the N-MOS and the third circuit module form a constant current circuit through the PWM comparator and the hysteresis comparator, and the PWM comparator is connected with the first hysteresis resistor. A hardware constant-current circuit is formed by a comparator, the defect that the suction force of a PWM driving electromagnetic coil is reduced along with the increase of the temperature is overcome, and continuous and stable electromagnetic suction force is ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to circuit technical field especially relates to a constant current's electromagnetic coil drive circuit structure. BACKGROUND

[0002] Now with the electromagnetic theory unceasingly in -depth, people have a more profound understanding of the nature of electromagnetic phenomena, provides the theoretical basis for the design and optimization of electromagnetic coil, in the material aspect, there is better conductive material and insulating material, make the electromagnetic coil performance get promotion, loss reduces, also make its safety and reliability improve, since the 20th century, electromagnetic coil has been widely applied in scientific research, industrial production, daily life and each field, with the rapid development of electronic technology and information technology, miniaturization, miniaturization of electromagnetic coil become the trend, at the same time, its precision and stability also require higher and higher.

[0003] At present, in the power electronic application, using PWM drive electromagnetic coil is a kind of widely used in relay, contactor, solenoid valve and other electromagnetic coil drive circuit control technology method. It can control the voltage of driving electromagnetic coil by adjusting the duty cycle of electronic switch tube, can adapt to different power supply voltage, has the characteristics of simple, efficient, accurate, stable, and also has the lowest cost, the most widely used, the most mature application circuit. In the process of using PWM drive electromagnetic coil, the voltage at both ends of the electromagnetic coil can be stably controlled by adjusting the duty cycle.

[0004] But the applicant found that the continuous work, the electromagnetic coil suction and current are proportional, therefore, in the case of stable voltage at both ends of the electromagnetic coil, the electromagnetic suction will decrease with temperature rise, in the scene and application with strict requirements for electromagnetic suction, using this PWM drive mode is not very suitable. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a kind of constant current's electromagnetic coil drive circuit structure, to make up the deficiency that the electromagnetic coil suction decreases with temperature rise when PWM drive circuit in prior art stabilizes voltage, and the PWM constant current control of the circuit is completely realized by hardware, reduce the demand for control peripheral.

[0006] To achieve the above object, the utility model provides the following technical scheme:

[0007] A kind of constant current's electromagnetic coil drive circuit structure including input control signal, first circuit module, second circuit module, third circuit module and pull-up voltage source;

[0008] The input control signal, first circuit module, second circuit module, third circuit module and pull-up voltage source are sequentially connected;

[0009] The second circuit module comprises a PWM comparator, a first hysteresis resistor, a hysteresis reference voltage source, a hysteresis comparator, a current-limiting resistor and an N-MOS connected in sequence, the PWM comparator is connected with the first circuit module, the N-MOS is connected with the third circuit module, and a constant current circuit is formed by the PWM comparator and the hysteresis comparator.

[0010] As an improvement, the first circuit module comprises a first input resistor, a second input resistor and a third input resistor connected in sequence, the first input resistor is connected to the input control signal, and the third input resistor is connected to the input end of the PWM comparator.

[0011] As an improvement, the third circuit module comprises a first feedback resistor and a second feedback resistor connected in sequence, one end of the first feedback resistor is connected to the S pole of the N-MOS, and a shunt resistor is further connected to the same end of the first feedback resistor, and the shunt resistor is used for circuit stabilization adjustment and current measurement detection setting.

[0012] As an improvement, the junction of the first feedback resistor and the second feedback resistor is further connected with a filter capacitor, and the other end of the filter capacitor is grounded, and the filter capacitor is used for protection and buffering setting, and the junction passes through the feedback resistor and is connected to the input end of the PWM comparator.

[0013] As an improvement, the second circuit module is further connected with a second hysteresis resistor, the second hysteresis resistor is connected to the output end and the input end of the hysteresis comparator, and the output end of the hysteresis comparator is connected to the G pole of the N-MOS through the current-limiting resistor.

[0014] As an improvement, the second circuit module further comprises an electromagnetic coil, a freewheeling diode and an electromagnetic coil power supply, one end of the electromagnetic coil is connected to the anode of the freewheeling diode together to the electromagnetic coil power supply, one end of the electromagnetic coil is connected to the cathode of the freewheeling diode together to the D pole of the N-MOS, the S pole of the N-MOS is connected to the ground through the shunt resistor, and the freewheeling diode plays a freewheeling protection setting.

[0015] As an improvement, a filter capacitor is connected between the first input resistor and the second input resistor, one end of the filter capacitor is connected to the ground, a filter capacitor is connected between the second input resistor and the third input resistor, one end of the filter capacitor is connected to the ground, and a filter capacitor is connected between the + input end and the - input end of the PWM comparator, and the filter capacitor, the filter capacitor and the filter capacitor play the buffering and frequency adjustment setting.

[0016] The utility model has the advantages of:

[0017] (1) The constant current electromagnetic coil driving circuit structure of the utility model, utilize the constant current circuit of comparator composition, through the constant comparison and feedback regulation of comparator, can real-time detection and adjustment current, make it keep in the vicinity of the set constant value, no matter how the load changes, such as load resistance increases or decreases, or power voltage appears fluctuation, constant current circuit can quickly make a response, automatically adjust output current, ensure the stability of output current, thereby for the load provides stable current supply, make current stability higher;

[0018] (2) The constant current electromagnetic coil driving circuit structure of the utility model, through the accuracy and parameter of the reference voltage source of comparator, sampling resistance and other related elements are reasonably selected, can realize the control and adjustment of constant current precision to a certain extent, satisfy the requirement of current precision in different scenes, can provide high-precision constant current, and the expansibility is stronger;

[0019] (3) The constant current electromagnetic coil driving circuit structure of the utility model, utilize comparator to solve the insufficient of the decrease of PWM drive electromagnetic coil suction with temperature increase, guarantee electromagnetic suction sustained and stable, avoid the electromagnetic coil and related circuit elements bear the load exceeding its rated value simultaneously, thereby increase overload risk, even possibly cause element damage and fire and other safety accidents.

[0020] In summary, the utility model discloses comparator effectively improve the current stability, reliability and safety. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is circuit structure schematic diagram of the utility model;

[0022] In the drawing: 1, input control signal, 2, first circuit module, 21, first input resistance, 22, second input resistance, 23, third input resistance, 24, first filter capacitor, 25, second filter capacitor, 26, third filter capacitor, 3, second circuit module, 30, electromagnetic coil power supply, 31, PWN comparator, 32, first hysteresis resistance, 33, hysteresis reference voltage source, 34, hysteresis comparator, 35, current limiting resistance, 36, N-MOS, 37, second hysteresis resistance, 38, electromagnetic coil, 39, freewheeling diode, 4, third circuit module, 41, first feedback resistance, 42, second feedback resistance, 43, shunt resistance, 44, filter capacitor, 45, feedback resistance, 5, pull-up voltage source. DETAILED DESCRIPTION

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] Example 1:

[0027] like Figure 1 As shown, a constant current electromagnetic coil driving circuit structure includes an input control signal 1, a first circuit module 2, a second circuit module 3, a third circuit module 4, and a pull-up voltage source 5.

[0028] The input control signal 1, the first circuit module 2, the second circuit module 3, the third circuit module 4, and the pull-up voltage source 5 are connected in sequence.

[0029] The second circuit module 3 includes a PWM comparator 31, a first hysteresis resistor 32, a hysteresis reference voltage source 33, a hysteresis comparator 34, a current limiting resistor 35, and an N-MOS 36 connected in sequence. The PWM comparator 31 is connected to the first circuit module 2, and the N-MOS 36 is connected to the third circuit module 4. The PWM comparator 31 and the hysteresis comparator 34 form a constant current circuit.

[0030] The first circuit module 2 comprises a first input resistor 21, a second input resistor 22 and a third input resistor 23 connected in sequence, the first input resistor 21 is connected to the input control signal 1, and the third input resistor 23 is connected to the input end of the PWM comparator 31.

[0031] The third circuit module 4 comprises a first feedback resistor 41 and a second feedback resistor 42 connected in sequence, one end of the first feedback resistor 41 is connected to the S pole of the N-MOS 36, and the same end of the first feedback resistor 41 is also connected with a shunt resistor 43, and the shunt resistor 43 is used for circuit stability adjustment and current measurement detection setting.

[0032] The junction of the first feedback resistor 41 and the second feedback resistor 42 is also connected with a filter capacitor 44, the other end of the filter capacitor 44 is grounded, and the filter capacitor 44 is used for protection and buffering setting, and the junction is connected to the input end of the PWM comparator 31 through a feedback resistor 45.

[0033] The second circuit module 3 is also connected with a second hysteresis resistor 37, which is connected to the output end and the input end of the hysteresis comparator 34, and the output end of the hysteresis comparator 34 is connected to the G pole of the N-MOS 36 through the current limiting resistor 35.

[0034] The second circuit module 3 further comprises an electromagnetic coil 38, a freewheeling diode 39 and an electromagnetic coil power supply 30, one end of the electromagnetic coil 38 and the anode of the freewheeling diode 39 are connected to the electromagnetic coil power supply 30 together, one end of the electromagnetic coil 38 and the cathode of the freewheeling diode 39 are connected to the D pole of the N-MOS 36 together, the S pole of the N-MOS 36 is connected to the ground through the shunt resistor 43, and the freewheeling diode 39 plays a role in freewheeling protection setting.

[0035] The first input resistor 21 and the second input resistor 22 are connected with one end of a first filter capacitor 24, the other end of the first filter capacitor 24 is grounded, the second input resistor 22 and the third input resistor 23 are connected with one end of a second filter capacitor 25, the other end of the second filter capacitor 25 is grounded, and the + input end and the - input end of the PWM comparator 31 are connected with a third filter capacitor 26, and the first filter capacitor 24, the second filter capacitor 25 and the third filter capacitor 26 play a role in buffering and adjusting frequency setting.

[0036] After the system is powered on, the circuit starts to work:

[0037] Phase one, the input control signal 1 has not started to control signal input, at this time the signal voltage is 0V, the + input of the PWN comparator 31 is also 0V, at this time there is no current flowing through the shunt resistor 43, the voltage fed back to the - input of the PWN comparator 31 through the feedback resistor 45, the first feedback resistor 41 and the second feedback resistor 42 is Ufb=bV>0V (b=3V3*R9 / (R9+R10), the PWN comparator 31 outputs 0V to the hysteresis comparator 34, the hysteresis comparator 34 follows the output 0V to the G pole of the N-MOS 36, and the N-MOS 36 is closed.

[0038] Phase two, the input control signal 1 starts to input signal, the input amplitude up voltage source 5, the frequency is 20Khz, the duty cycle is Duty, the PWN signal is filtered by the low-frequency series RC filter composed of the first input resistor 21, the second input resistor 22, the third input resistor 23 and the first filter capacitor 24, the second filter capacitor 25 and the third filter capacitor 26, and a stable voltage signal up voltage source 5*Duty is formed at the + input of the PWN comparator 31; at this time, there is no current flowing through the shunt resistor 43, the voltage fed back to the - input of the PWN comparator 31 through the feedback resistor 45 is bV, which is less than the up voltage source 5*Duty, the PWN comparator 31 outputs flip to high level, the hysteresis comparator 34 flips to high level to the G pole of the N-MOS 36, and then the N-MOS 36 is opened, the current IL flows through the electromagnetic coil power supply 30, the electromagnetic coil 38, the DS of the N-MOS 36, the shunt resistor 43 to the ground, and gradually increases.

[0039] Phase three, after the input control signal 1 inputs signal, the N-MOS 36 is opened, and the current IL flowing through the electromagnetic coil 38 gradually increases, at this time, the voltage Ufb=k*IL+b (k=R8*R10 / (R9+R10) is fed back to the - input of the PWN comparator 31 through the feedback resistor 45, the first feedback resistor 41 and the second feedback resistor 42, when Ufb is greater than the up voltage source 5*Duty, the PWN comparator 31 outputs flip to 0V, the hysteresis comparator 34 follows the output 0V to the G pole of the N-MOS 36, and the N-MOS 36 is closed, the current flowing through the electromagnetic coil 38, the current IL gradually decreases.

[0040] Phase four, when Ufb is greater than the up voltage source 5*Duty, the N-MOS 36 is closed, the current flowing through the shunt resistor 43 is shut off to 0A by the N-MOS 36, the voltage Ufb=bv fed back to the - input of the PWM comparator 31 is less than the up voltage source 5*Duty, the PWM comparator 31 outputs flip to high level again, then the N-MOS 36 is opened again, the current flowing through the electromagnetic coil 38, the current IL increases again, and then repeats the stable work in phase three and four, at this time the stable current ILs=(3V3*Duty-b) / k.

[0041] The constant current electromagnetic coil driving circuit uses the comparator fast comparison to realize the MOS tube fast opening and shutting, so that the average current in the electromagnetic coil is constant, and in specific applications, different third filter capacitors 26, filter capacitors 44, feedback resistors 45 and shunt resistors 43 can be selected according to different application scenes to adjust the switching frequency, so that the best working state is achieved.

[0042] The above merely describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A constant current electromagnetic coil driving circuit structure, characterized in that: it comprises an input control signal (1), a first circuit module (2), a second circuit module (3), a third circuit module (4) and a pull-up voltage source (5) connected in sequence; the second circuit module (3) comprises a PWM comparator (31), a first hysteresis resistor (32), a hysteresis reference voltage source (33), a hysteresis comparator (34), a current limiting resistor (35) and an N-MOS (36) connected in sequence, the PWM comparator (31) is connected with the first circuit module (2) and the third circuit module (4) respectively, and the PWM comparator (31) cooperates with the hysteresis comparator (34) to form a constant current circuit.

2. The constant current electromagnetic coil driving circuit structure according to claim 1, characterized in that: the first circuit module (2) comprises a first input resistor (21), a second input resistor (22) and a third input resistor (23) connected in sequence, one end of the first input resistor (21) is connected to the input control signal (1), and the other end of the third input resistor (23) is connected to the input end of the PWM comparator (31).

3. The constant current electromagnetic coil driving circuit structure according to claim 1, characterized in that: the third circuit module (4) comprises a first feedback resistor (41) and a second feedback resistor (42) connected in sequence, one end of the first feedback resistor (41) is connected to the S pole of the N-MOS (36), and the same end of the first feedback resistor (41) is also connected with a shunt resistor (43) for circuit stabilization adjustment and current measurement detection.

4. The constant current electromagnetic coil driving circuit structure according to claim 3, characterized in that: the connection point of the first feedback resistor (41) and the second feedback resistor (42) is also connected with a filter capacitor (44), the other end of the filter capacitor (44) is grounded, the filter capacitor (44) is used for protection and buffering, and the connection point of the first feedback resistor (41) and the second feedback resistor (42) is connected to the input end of the PWM comparator (31) through a feedback resistor (45).

5. The constant current electromagnetic coil driving circuit structure according to claim 1, characterized in that: the second circuit module (3) is also connected with a second hysteresis resistor (37) connected to the output end and the input end of the hysteresis comparator (34), and the output end of the hysteresis comparator (34) is connected to the G pole of the N-MOS (36) through the current limiting resistor (35).

6. The constant current electromagnetic coil driving circuit structure according to claim 4, characterized in that: ​ ​ ​ ​ ​ ​ The second circuit module (3) further comprises an electromagnetic coil (38), a freewheeling diode (39) and an electromagnetic coil power supply (30), one end of the electromagnetic coil (38) and an anode of the freewheeling diode (39) are respectively connected to the electromagnetic coil power supply (30), the other end of the electromagnetic coil (38) and a cathode of the freewheeling diode (39) are respectively connected to a D pole of the N-MOS (36), an S pole of the N-MOS (36) is connected to the ground through a shunt resistor (43), and the freewheeling diode (39) serves as a freewheeling protection setting.

7. The constant current electromagnetic coil driving circuit structure according to claim 2, characterized in that: The first input resistor (21) and the second input resistor (22) are connected to one end of a first filter capacitor (24), and the other end of the first filter capacitor (24) is grounded; the second input resistor (22) and the third input resistor (23) are connected to one end of a second filter capacitor (25), and the other end of the second filter capacitor (25) is grounded; and the positive input end and the negative input end of the PWM comparator (31) are connected to a third filter capacitor (26), and the first filter capacitor (24), the second filter capacitor (25) and the third filter capacitor (26) serve as a buffer and a frequency adjustment setting.

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