CN111610813A

CN111610813A - Constant-current driving circuit of electromagnetic valve for automobile

Info

Publication number: CN111610813A
Application number: CN202010371698.3A
Authority: CN
Inventors: 李泉; 何丽红
Original assignee: Hunan Institute of Engineering
Current assignee: Hunan Institute of Engineering
Priority date: 2020-05-06
Filing date: 2020-05-06
Publication date: 2020-09-01
Anticipated expiration: 2040-05-06
Also published as: CN111610813B

Abstract

The invention discloses a constant current driving circuit of an electromagnetic valve for an automobile, which comprises: the electromagnetic valve current driving part amplifies the current of the PWM driving signal through a power MOS tube; a solenoid valve current sampling unit for sampling a drive current of the solenoid valve and converting a current signal into a voltage signal; the PID control part compares the sampling current of the electromagnetic valve with a target current set value, outputs a control signal through the PID control circuit, and adjusts a PWM driving signal of the electromagnetic valve in real time to realize constant current driving control of the electromagnetic valve. The driving circuit overcomes the defects of high cost and low response speed of the automobile electromagnetic valve in the prior art due to the need of an additional computer software and hardware closed-loop control system.

Description

Constant-current driving circuit of electromagnetic valve for automobile

Technical Field

The invention belongs to the technical field of electromagnetic valve driving, and relates to an electromagnetic valve constant-current driving circuit for an automobile.

Background

With the annual increase of the proportion of the whole automobile automatic transmission, the mode of executing control of the transmission by adopting electromagnetic valves such as electro-hydraulic proportion and the like is more and more extensive. A general proportional solenoid valve generally adopts a PWM (pulse width modulation) signal to perform driving control, and controls the current of a proportional electromagnet on the solenoid valve by adjusting the duty ratio of the PWM signal, so as to control parameters such as the output pressure and the flow rate of the solenoid valve. Because the working environment temperature of the automotive electromagnetic valve has a very large variation range (the lowest temperature reaches-40 ℃, and the highest transmission oil temperature exceeds 100 ℃), the resistance value of the electromagnetic valve electromagnet changes along with the temperature variation, so that the current of the electromagnetic valve is driven by the same PWM signal, and the output characteristics are changed due to different working temperatures. At present, it is a common practice to compare signals such as output pressure and flow rate of an electromagnetic valve with target set values by using control software of a computer, and perform closed-loop control by using software PID to automatically change the duty ratio of a PWM signal to realize automatic control of output.

However, in the existing drive control method, because a computer or a processor chip is needed to cooperate to perform complex signal processing and operation, the response speed of closed-loop control is slow, and for some electro-hydraulic proportional control devices without a computer control system, closed-loop control cannot be performed, and the control accuracy of a hydraulic system cannot be guaranteed.

Therefore, a constant current driving circuit or method for an automotive solenoid valve is needed to overcome the defects of high cost and low response speed caused by the need of an additional computer software and hardware closed-loop control system in the prior art.

Disclosure of Invention

Technical problem to be solved

Based on the above, the invention discloses a constant current driving circuit of an automobile electromagnetic valve, which can overcome the defects of high cost and low response speed of the automobile electromagnetic valve in the prior art due to the need of an additional computer software and hardware closed-loop control system.

(II) technical scheme

The invention discloses a constant current driving circuit of an automotive solenoid valve, which comprises a solenoid valve current driving part, a solenoid valve current sampling part, a PID control part and a PWM waveform generating part, wherein the solenoid valve current driving part comprises a comparator U1B, resistors R6-R8, a capacitor C2, an NMOS tube Q1 and diodes D1-D2, a power supply voltage end VCC is connected with one end of a solenoid valve L1, one end of R6, one end of R7 and a cathode of D2, an anode of D2 and the other end of L1 are connected to a drain of Q1, a grid of Q1 is connected with one end of R8 and the cathode of D1, the other end of R7 and the other end of R8 are simultaneously connected to an output end of U1B, a source of Q1 is connected with an anode of D1, the other end of R6 is connected with one end of C2 and a same-phase end of U1B, and the other end of C2 is connected with a ground end; the electromagnetic valve current sampling part comprises resistors R9-R13, a capacitor C3 and a comparator U1C, wherein one end of R9 is connected with a source of Q1 and one end of R10, the other end of R9 is connected with a ground end GND, one end of R11 and one end of a capacitor C3, the other ends of C3 and R10 are connected with a non-inverting end of U1C, the other end of R11 is connected with one end of R12 and an inverting end of U1C, and the other end of R12 is connected with an output end of U1C and one end of R13; the PID control part comprises resistors R14-R20, comparators U1D and U2A and capacitors C4 and C5, wherein the inverting end of U1D is connected with the other end of the resistor R D and one end of the resistor R D, the inverting end of U1D is connected with one ends of the R D and the R D, the other end of the R D is connected with an input signal end IN, the other end of the R D is connected with a ground terminal GND, the output end of U1D is connected with the other end of the R D, one end of the C D and one end of the R D, the inverting end of U2D is connected with the other end of the C D, the other end of the R D and one end of the R D, the inverting end of the U2D is connected with the GND through the resistor R D, the other end of the R D is connected with one end of the C D, the output end of the U2D is connected with the other end of the C D and one end of the R D. The output terminal of the PWM waveform generating section is connected to the inverting terminal of U1B.

Further, the PWM waveform generator includes resistors R1 to R5, a capacitor C1, and a comparator U1A, an output end of the PWM waveform generator is an inverting end of the comparator U1A, an inverting end of U1A is connected to an inverting end of the comparator U1B, one end of C1, and one end of R5, a non-inverting end of U1A is connected to one end of R3, one end of R4, and one end of R1, the other ends of C1 and R4 are connected to a ground GND, an output end of U1A is connected to the other ends of R3, R2, and R5, and the other ends of R2 and R1 are connected to the supply voltage terminal VCC.

Further, the PWM waveform generating section is a function generator including an integrated chip MAX 038.

Further, the solenoid valve L1 is a proportional solenoid valve.

Further, the diode D1 is a zener diode, and the type of the diode D2 is FR 107.

Further, positive power terminals of the five comparators U1A, U1B, U1C, U1D and U2A are all connected to the supply voltage terminal VCC, and negative power terminals are all connected to the ground terminal GND.

Furthermore, an individual diode is connected between the drain electrode and the source electrode of the NMOS tube Q1 in anti-parallel.

(III) advantageous effects

Compared with the prior art, the invention has the following beneficial effects:

(1) the constant current driving circuit can detect the current of the electromagnetic valve in real time, and when the current changes due to the change of the resistance of a valve coil caused by the change of the environmental temperature of the electromagnetic valve, the PID control circuit can automatically adjust the pulse width of the PWM output signal in real time according to the current deviation, thereby ensuring that the current of the electromagnetic valve is in a constant current driving state.

(2) The constant current driving circuit adopts a hardware PID design, realizes the integrated design of the automatic closed-loop constant current control, the current sampling and the PWM waveform generation of the electromagnetic valve, has simple circuit structure, low cost and high reliability, does not need any software method, and is suitable for batch production and installation in the automobile gearbox for use.

Drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:

fig. 1 is a circuit diagram of constant current driving of an automotive solenoid valve according to an embodiment of the present invention.

Detailed Description

The present invention will be described more fully hereinafter with reference to the accompanying drawings and examples, in which the technical problems and advantages of the present invention are solved, wherein the described examples are only intended to facilitate the understanding of the present invention, and are not to be construed as limiting in any way.

As shown in fig. 1, the constant current driving circuit for an automotive solenoid valve according to the present invention includes a solenoid valve current driving portion, a solenoid valve current sampling portion, a PID control portion, and a PWM waveform generating portion, wherein the circuit structure of each portion is as follows:

1) electromagnetic valve current driving part

The solenoid valve current driving part comprises a comparator U1B, resistors R6-R8, a capacitor C2, an NMOS tube Q1 and diodes D1-D2, wherein a power supply voltage end VCC is connected with one end of a solenoid valve L1, one end of an R6, one end of an R7 and a cathode of a diode D2, an anode of the diode D2 and the other end of a proportional solenoid valve L68628 are connected to a drain of Q1, a grid of Q1 is connected with one end of a resistor R8 and a cathode of a diode D1, the other end of R7 and the other end of R8 are connected to an output end of the comparator U1B, a source of Q1 is connected with an anode of the diode D1, the other end of the R1 is connected with one end of the C1 and the same-phase end of the U1 1, and the other end of the C1 is connected with.

In the solenoid valve current driving part, the solenoid valve L1 for the automobile may be preferably a proportional solenoid valve, the solenoid valve L1 may be regarded as a series circuit of a resistor and an inductor when operating, the impedance value of L1 is changed when the temperature is changed, the PWM pulse signal output by the pin 7 of the comparator U1B is connected to the gate of the Q1 through the R8, and the on and off of the NMOS transistor Q1 is controlled by the changed PWM pulse width, so that the current flowing through the solenoid valve L1 is changed.

2) Electromagnetic valve current sampling part

The electromagnetic valve current sampling part comprises resistors R9-R13, a capacitor C3 and a comparator U1C, wherein one end of the resistor R9 is connected with a source of Q1 and one end of R10, the other end of the resistor R9 is connected with a ground terminal GND, one end of the R11 and one end of the capacitor C3, the other ends of the resistor C3 and the R10 are connected with the same-phase end of the comparator U1C, the other end of the R11 and one end of the R12 are connected with the opposite-phase end of the comparator U1C, and the other end of the R12 is connected with the output end of the comparator U1C and one end of the R13.

In the solenoid valve current sampling unit, a current sampling resistor R9 connected in series to the solenoid valve L1 detects the current of the solenoid valve L1, converts the current signal into a voltage signal, passes through a low-pass filter composed of R10 and C3 and an amplifier circuit composed of U1C, R11 and R12, amplifies the current sampling signal, and then enters the PID control unit through R13.

3) PID control unit

The PID control part comprises resistors R14-R20, comparators U1D and U2A and capacitors C4 and C5, wherein the inverting end of the comparator U1D is connected with the other end of the resistor R D and one end of the resistor R D, the inverting end of the comparator U1D is connected with one ends of the resistors R D and R D, the other end of the R D is connected with an input signal end IN, the other end of the R D is connected with a ground end GND, the output end of the comparator U1D is connected with the other end of the R D, one end of the C D and one end of the R D, the inverting end of the comparator U2D is connected with the other end of the C D, the other end of the R D and one end of the R D, the inverting end of the comparator U2D is connected with the ground end GND through the resistor R D, the other end of the R D is connected with one end of the C D, the other end of the comparator U2D is connected with the driving current of the comparator U D.

IN the PID controller, a PID controller is configured by U1D, U2A and related components, a current target set value is given by an input signal terminal IN, a sampled current signal and a target value are input to subtractors U1D and R14, and an error signal is compared with a triangular wave output by a PWM waveform generator via a PID controller configured by U2A, C4, R17, R20, R18 and C5 at a non-inverting terminal where the error signal is output to a comparator U1B via R19.

4) PWM waveform generating section

The PWM waveform generating part comprises resistors R1-R5, a capacitor C1 and a comparator U1A, wherein the inverting end of the comparator U1A is connected with the inverting end of the comparator U1B, one end of C1 is connected with one end of R5, the inverting end of the comparator U1A is connected with one end of R3, one end of R4 and one end of R1, the other end of C1 and the other end of R4 are connected with a ground end GND, the output end of the comparator U1A is connected with the other end of R3, one end of R2 and the other end of R5, and the other end of R2 and the other end of R1 are connected with a supply voltage end VCC.

In the PWM waveform generator, U1A, R1-R5, and C1 constitute a triangular wave carrier generator, and the input of the comparator U1B is the control voltage signal of the triangular wave and PID output, and the output is the PWM pulse signal for driving Q1.

It should be particularly noted that the PWM waveform generating unit in section 4) above is not limited to the circuit structure shown in fig. 1, but may also be an analog circuit of another function generator, or may also be a signal generator implemented by an integrated circuit of a function generator, such as a function generating chip MAX038, and the PWM signal output by the PWM waveform generating unit is connected to the inverting terminal of the comparator U1B, and then constant current feedback control can be performed through the operational amplifier U1B, so as to adjust the PWM pulse signal width in real time according to the collected current, and implement constant current driving control.

As can be seen from the above description of sections 1) to 4), the functions of the sections are as follows: the electromagnetic valve current driving part amplifies the current of the PWM driving signal through a power MOS tube; a solenoid valve current sampling unit for sampling a drive current of the solenoid valve and converting a current signal into a voltage signal; the PID control part compares the sampling current of the electromagnetic valve with a target current set value, outputs a control signal through a PID control circuit, and adjusts a PWM (pulse width modulation) driving signal of the electromagnetic valve in real time to realize constant current driving control of the electromagnetic valve; and a PWM pulse signal generating part for generating PWM waveform through a triangular wave generator and a comparator for driving control of the electromagnetic valve. When the self impedance of the electromagnetic valve L1 for the electric automobile changes due to the temperature change or the influence of other factors, the current sampling signal output by the current sampling part changes along with the change, so that the control signal output by the PID control part changes, and the PWM pulse signal width is further adjusted by the current driving part, so that the electromagnetic valve current is corrected, and the constant current driving control of the electromagnetic valve for the automobile is realized, therefore, the constant current driving circuit of the electromagnetic valve L1 is not only limited to be installed in a gearbox for use, but also can be used in other environments with large temperature difference change.

Further, the diode D1 is preferably a zener diode, the diode D2 is preferably FR107, the positive power terminals of the five comparators U1A, U1B, U1C, U1D, and U2A are all connected to the supply voltage terminal VCC, and the negative power terminals thereof are all connected to the ground terminal GND; and the NMOS transistor Q1 may be connected in anti-parallel with a body diode (not shown in fig. 1) between the drain and the source to protect the NMOS transistor.

As is apparent from the above description, the components of the present invention are as follows in total: five comparators (namely operational amplifiers) U1A, U1B, U1C, U1D, U2A, twenty resistors R1-R20, five capacitors C1-C5, two diodes D1-D2 and an NMOS tube. The driving circuit of the electromagnetic valve has fewer required devices, a single chip microcomputer and other integrated chips and a current sensor are not required, the cost is greatly reduced, current PID closed-loop control can be realized through pure hardware through the traditional devices, and the electromagnetic valve can freely work in an automobile running environment with large temperature change.

In the above embodiments provided in the present invention, it should be understood that the disclosed constant current driving circuit may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units and units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form. The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment. In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

Finally, the description is as follows: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. The constant-current driving circuit of the electromagnetic valve for the automobile is characterized by comprising an electromagnetic valve current driving part, an electromagnetic valve current sampling part, a PID control part and a PWM waveform generating part, wherein the electromagnetic valve current driving part comprises a comparator U1B, resistors R6-R8, a capacitor C2, an NMOS tube Q1 and diodes D1-D2, a power supply voltage end VCC is connected with one end of an electromagnetic valve L1, one end of R6, one end of R7 and a cathode of D2, an anode of D2 and the other end of L1 are connected to a drain of Q1, a grid of Q1 is connected with one end of R8 and the cathode of D1, the other end of R7 and the other end of R8 are simultaneously connected to an output end of U1B, a source of Q1 is connected with an anode of D1, the other end of R6 is connected with one end of C2 and a same-phase end of U1B, and the other end of C2 is connected with a ground; the electromagnetic valve current sampling part comprises resistors R9-R13, a capacitor C3 and a comparator U1C, wherein one end of R9 is connected with a source of Q1 and one end of R10, the other end of R9 is connected with a ground end GND, one end of R11 and one end of a capacitor C3, the other ends of C3 and R10 are connected with a non-inverting end of U1C, the other end of R11 is connected with one end of R12 and an inverting end of U1C, and the other end of R12 is connected with an output end of U1C and one end of R13; the PID control part comprises resistors R14-R20, comparators U1D and U2A and capacitors C4 and C5, wherein the inverting end of U1D is connected with the other end of the resistor R D and one end of the resistor R D, the inverting end of U1D is connected with one ends of the R D and the R D, the other end of the R D is connected with an input signal end IN, the other end of the R D is connected with a ground terminal GND, the output end of U1D is connected with the other end of the R D, one end of the C D and one end of the R D, the inverting end of U2D is connected with the other end of the C D, the other end of the R D and one end of the R D, the inverting end of the U2D is connected with the GND through the resistor R D, the other end of the R D is connected with one end of the C D, the output end of the U2D is connected with the other end of the C D and one end of the R D. The output terminal of the PWM waveform generating section is connected to the inverting terminal of U1B.

2. The constant current driving circuit according to claim 1, wherein the PWM waveform generating portion includes resistors R1 to R5, a capacitor C1, and a comparator U1A, an output terminal of the PWM waveform generating portion is an inverting terminal of the comparator U1A, an inverting terminal of U1A is connected to an inverting terminal of the comparator U1B, one end of C1, and one end of R5, a non-inverting terminal of U1A is connected to one end of R3, one end of R4, and one end of R1, the other ends of C1 and R4 are connected to a ground terminal GND, an output terminal of U1A is connected to the other end of R3, one end of R2, and the other end of R5, and the other ends of R2 and R1 are connected to the supply voltage terminal VCC.

3. The constant current drive circuit according to claim 1, wherein the PWM waveform generation section is a function generator including an integrated chip MAX 038.

4. The constant current driving circuit according to claim 1, wherein the solenoid valve L1 is a proportional solenoid valve, and a current target setting value is given through the input signal terminal IN.

5. The constant current driving circuit according to claim 1, wherein the diode D1 is a zener diode, and the type of the diode D2 is FR 107.

6. The constant current driving circuit according to claim 2, wherein positive power supply terminals of the five comparators U1A, U1B, U1C, U1D, U2A are all connected to a supply voltage terminal VCC, and negative power supply terminals are all connected to a ground terminal GND.

7. The constant current driving circuit as claimed in claim 1, wherein a body diode is connected in anti-parallel between the drain and the source of the NMOS transistor Q1.