JP2009232649A - Linear solenoid driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear solenoid driving device capable of correcting the temperature characteristics of circuit itself configuring a control system. <P>SOLUTION: A temperature corrector 12 detects the temperatures of circuit boards loading each circuit for the driving device 1, and the temperature characteristics of a PWM driving signal are corrected in response to the results of the detections. Consequently, the temperature characteristics of each circuit are reflected and the temperature characteristics being latent in a feedback control system are corrected, and a current driving a linear solenoid 7 is controlled with a high accuracy. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a linear solenoid driving apparatus that performs PWM control of a driving switching element connected in series with a linear solenoid between a power source and a ground.

  FIG. 7 shows an example of the configuration of a conventional linear solenoid drive device. The D / V conversion circuit 2 of the driving device 1 converts a control command given as a DUTY signal from an external ECU (Electronic Control Unit) or the like into a voltage signal and outputs the voltage signal to the feedback control unit 3. The feedback control unit 3 outputs a difference signal between the control command and a voltage conversion signal of a detection current described later to the V / D conversion circuit 4 (PWM drive signal generation circuit) (see FIG. 8A). The V / D conversion circuit 4 compares the difference signal with a triangular wave signal which is a PWM control carrier wave output from the triangular wave generation circuit 5 to generate a PWM signal (see FIGS. 8B and 8C). ).

  A series circuit of an N-channel MOSFET 6, a linear solenoid 7 and a current detecting resistor element 8 is connected between the power supply VB and the ground. A free wheel diode 9 is connected between the drain of the FET 6 and the ground. Connected in the opposite direction. The linear solenoid 7 controls the opening and closing of a valve that adjusts the air flow rate, for example, to generate air pressure for operating a clutch of the vehicle. Both ends of the resistance element 8 are connected to an I / V conversion circuit 10 (current detection circuit). The I / V conversion circuit 10 has a current that flows through the resistance element 8 when the FET 6 is turned on (FIG. 8D). Reference) is detected as a voltage, and the detection result is output to the feedback control unit 3. FIG. 8D shows a case where the control target is 1A, for example.

By the way, in said drive device 1, since each circuit part has a negative temperature characteristic, there exists a problem that the electric current supplied to the linear solenoid 7 also has a negative temperature characteristic as a result. For example, in Patent Document 1, there is a problem that an error occurs in the control current due to a change in the resistance value of the linear solenoid in accordance with the ambient temperature, and learning is performed so as to correct the resistance value of the linear solenoid obtained in advance. This is reflected in the feedback control gain.
Japanese Patent Laid-Open No. 9-280411

However, Patent Document 1 does not pay any attention to the fact that the circuit itself constituting the control system has temperature characteristics. Therefore, even if the resistance value of the linear solenoid is corrected, the temperature characteristic that is latent in the feedback control is not excluded, and there is no guarantee that the current control is executed with high accuracy.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a linear solenoid driving device capable of correcting temperature characteristics of a circuit itself constituting a control system.

  According to the linear solenoid drive device of claim 1, the temperature correction circuit detects the temperature of the circuit board on which the duty / voltage conversion circuit, the current detection circuit, the command voltage generation circuit, the PWM drive signal generation circuit, and the like are mounted. Then, the temperature characteristic of the PWM drive signal is corrected according to the detection result. Therefore, by reflecting the temperature characteristics of each circuit, the temperature characteristics latent in the feedback control system can be corrected, and the current for driving the linear solenoid can be controlled with high accuracy.

  According to the linear solenoid drive device of claim 2, the temperature correction circuit supplies the current to the comparison reference voltage input terminal of the operational amplifier constituting the integration circuit in the duty / voltage conversion circuit by the current supply circuit. A reference voltage generation circuit for applying a reference voltage for determining the reference voltage is configured to have a positive temperature characteristic. Then, as the temperature rises, the potential at the comparison reference voltage input terminal of the operational amplifier rises, so that the integrated value of the control command signal that is the output of the duty / voltage conversion circuit rises. As a result, since a positive temperature characteristic can be imparted to the PWM drive signal, the negative temperature characteristic of the entire control system can be canceled.

  According to the linear solenoid driving apparatus of the third aspect, the reference voltage generating circuit is configured by a series circuit of a diode and a resistance element connected between a power source and a ground. That is, since the forward voltage of the diode has a negative temperature characteristic, a positive temperature characteristic can be given to the reference voltage generated at the common connection point with the resistance element.

  According to the linear solenoid drive device of the fourth aspect, the temperature supplied from the temperature correction circuit to the comparison reference voltage input terminal of the operational amplifier constituting the integration circuit in the duty / voltage conversion circuit is detected by the current supply circuit. It is configured to increase in the process of rising. Therefore, as in the case of claim 2, as the temperature rises, the comparison reference voltage is raised to increase the integrated value of the control command signal, and a positive temperature characteristic can be imparted to the PWM drive signal. .

  According to the linear solenoid drive device of the fifth aspect, the current supply unit is inserted between the current supply circuit and the comparison reference voltage input terminal of the operational amplifier according to a change in the forward voltage of the temperature detection diode. The switch circuit is configured to be intermittent, and the temperature correction circuit is configured by including one or more current supply units. In other words, if the diode changes the forward voltage with a negative temperature characteristic according to the detected temperature and closes the switch circuit as the temperature rises, it supplies current to the reference voltage input terminal of the operational amplifier. Thus, the comparison reference voltage can be increased.

  According to the linear solenoid drive device of the sixth aspect, the switch circuit of the current supply unit is constituted by a transistor, and the conduction control of the transistor is performed according to the result of the operational amplifier comparing the forward voltage of the diode and the reference voltage. To do. In other words, when the temperature detected by the diode rises and the forward voltage decreases, the current can be supplied to the reference voltage input terminal of the operational amplifier by turning on the transistor as a result of comparison with the reference voltage.

  According to the linear solenoid drive device of the seventh aspect, the temperature correction circuit is configured as a reference voltage generation circuit that gives a comparison reference voltage having a positive temperature characteristic to an operational amplifier that constitutes an integration circuit of the duty / voltage conversion circuit. . That is, if a positive temperature characteristic is given to the comparison reference voltage given to the operational amplifier, the integrated value of the control command signal can be raised by directly raising the reference voltage as the temperature rises.

  According to the linear solenoid driving device of the eighth aspect, the reference voltage generating circuit is configured by a series circuit of a diode and a resistance element connected between the power source and the ground. In this way, if the common connection point of both is connected to the comparison reference voltage input terminal of the operational amplifier, the cathode potential of the diode will drop by the forward voltage of the diode from the power supply voltage. The comparison reference voltage can be increased according to the above.

  According to the linear solenoid drive device of the ninth aspect, the temperature correction circuit is arranged in the vicinity of the command voltage generation circuit. That is, in the configuration of the control system assumed by the present invention, the command voltage generation that generates the PWM command voltage according to the difference between the voltage signal converted by the duty / voltage conversion circuit and the voltage signal converted by the current detection circuit Circuits tend to have relatively strong negative temperature characteristics. Accordingly, the temperature correction circuit corrects the temperature characteristic according to the temperature near the command voltage generation circuit, so that a good correction result can be obtained.

(First embodiment)
A first embodiment of the present invention will be described below with reference to FIGS. Note that the same parts as those in FIG. 7 are denoted by the same reference numerals and description thereof is omitted, and different parts will be described below. FIG. 1 shows the configuration of the drive device 11 of this embodiment. The drive device 11 is configured by adding a temperature corrector 12 (temperature correction circuit) to the drive device 1 shown in FIG. The temperature corrector 12 detects the temperature of the circuit board on which the circuit components of the driving device 11 are mounted, and controls the control command voltage in the D / V conversion circuit 2 (duty / voltage conversion circuit) according to the detected temperature. The conversion characteristic is corrected.

  FIG. 2 shows a temperature corrector 12 together with a specific configuration of the D / V conversion circuit 2. The D / V conversion circuit 2 is configured as an integration circuit centered on the operational amplifier OP1. A series circuit of resistance elements R1 and R2 and a series circuit of resistance elements R3 and R4 are connected between the power source V1 and the ground, and a common connection point of the resistance elements R1 and R2 is connected via the resistance element R5. The common connection point of the resistance elements R3 and R4 is connected to the non-inverting input terminal of the operational amplifier OP1. The resistance elements R2 and R5 are variable resistors. A parallel circuit of a capacitor C1 and a resistor element R6 is connected between the inverting input terminal and the output terminal of the operational amplifier OP1.

  The control command signal DUTY is connected to the base of the NPN transistor 13, the collector of the transistor 13 is connected to the common connection point of the resistance elements R1 and R2, and the emitter is connected to the ground. The temperature corrector 12 includes a temperature detector 14 and a constant current source 15 (current supply circuit). The common connection point of the resistance elements R3 and R4 is to provide the reference voltage Vth1 for comparison to the operational amplifier OP1, and the temperature corrector 12 is supplied with a constant current from the constant current source 15 according to the temperature detected by the temperature detector 14. Is supplied to the common connection point.

Hereinafter, the operation of the D / V conversion circuit 2 will be described. The reference voltage Vth1 is expressed by equation (1).
Vth1 = V1 × R4 / (R3 + R4) (1)
The potential Vth2H when the transistor 13 is OFF as the potential Vth2 at the common connection point of the resistance elements R3 and R4 is expressed by equation (2).
Vth2H = (V1 / R1 + Vth1 / R5) × 1 / (1 / R1 + 1 / R2 + 1 / R5)
... (2)
Further, the potential Vth2L when the transistor 13 is ON is equal to the collector-emitter voltage VCE of the transistor 13, for example, Vth2L = 0.05 V (3)
Degree.

When the control command signal DUTY has a duty of 100%, the output voltage OUT _100% of the operational amplifier OP1 is
OUT _100% = (Vth1−Vth2L) × R6 / R5 + Vth1 (4)
The output voltage OUT _0% when the control command signal DUTY has a duty of _0% is
OUT _0% = (Vth1−Vth2H) × R6 / R5 + Vth1 (5)
It becomes. The output voltage OUT _X% when the control command signal DUTY is the duty _X% is
OUT _X% = OUT _100% x (X / 100)
+ OUT _0% x {(100-X) / 100)} (6)
It becomes. That is, if the reference voltage Vth1 rises as the temperature rises, the output voltage OUT _X% rises, so that a positive temperature characteristic can be imparted.

  FIG. 3 shows a specific configuration example of the temperature detector 12. In the constant current source 15, the emitters of the PNP transistors 16a and 16b constituting the mirror pair are connected to the power source V3, and the bases of both are connected to the emitter of the PNP transistor 18 via the resistance element 17. The collector of the transistor 18 is connected to the ground. The base of the transistor 18 is connected to the collector of the NPN transistor 19 together with the collector of the transistor 16 a, and the emitter of the transistor 19 is connected to the ground via the resistance element 20. The collector of the transistor 16b is connected to the non-inverting input terminal of the operational amplifier OP1.

  A series circuit of a resistance element 21 and a PNP transistor 22 is connected between the power supply V3 and the ground, and a base of the transistor 19 is connected to a common connection point between them (emitter of the transistor 22). In addition, a series circuit of a diode D1 and a resistance element 23 is connected between the power supply V4 and the ground, and a common connection point between both is connected to the base of the transistor 22 via the resistance element 24. The diode D1 and the resistance element 23 constitute a reference voltage generation circuit 25.

  In the case of a general constant current source, a reference voltage based on, for example, a band gap reference (BGR) having no temperature characteristic is applied to the base of the transistor 22 that determines the constant current value via the resistance element 24. In this embodiment, a series circuit of the diode D1 and the resistance element 23 is connected. The diode D1 corresponds to the temperature detector 14, and the forward voltage Vf has a negative temperature characteristic. Therefore, the voltage applied at the common connection point with the resistance element 23 has a positive temperature characteristic. The diode D1 is arranged as close as possible to the feedback control unit 3 (command voltage generation circuit). That is, it is because the feedback control unit 3 has the strongest negative temperature characteristic in the control system of the driving device 11.

As a result, as an operation of the constant current source 15, when the temperature detected by the diode D1 rises, the constant current I supplied to the non-inverting input terminal of the operational amplifier OP1 increases. Then, since the reference voltage Vth1 rises, the output voltage OUT _X% rises, and a positive temperature characteristic can be imparted. Therefore, as shown in FIG. 4, the negative temperature characteristic of the control system, that is, the control current supplied to the linear solenoid 7 is canceled by the positive temperature characteristic applied to the reference voltage Vth1, and the temperature characteristic is canceled. can do.

  As described above, according to the present embodiment, the temperature corrector 12 detects the temperature of the circuit board on which each circuit of the driving device 11 is mounted, and the PWM drive signal has according to the detection result. Since the temperature characteristic of each circuit is reflected, the temperature characteristic latent in the feedback control system is corrected, and the current for driving the linear solenoid 7 can be controlled with high accuracy.

  In that case, the temperature corrector 12 supplies current to the non-inverting input terminal to which the comparison reference voltage Vth1 is applied to the operational amplifier OP1 constituting the integrating circuit in the D / V conversion circuit 2 by the constant current source 15, and the current value Since the reference voltage generating circuit 25 for applying the reference voltage for determining the reference voltage is configured to have a positive temperature characteristic, the integration of the control command signal, which is the output of the D / V conversion circuit 2, as the detected temperature increases. Since the positive temperature characteristic can be given to the PWM drive signal by increasing the value, the negative temperature characteristic of the entire control system can be canceled.

Since the reference voltage generating circuit 25 is constituted by a series circuit of the diode D1 connected between the power source and the ground and the resistance element 24, the negative temperature characteristic of the forward voltage of the diode D1 can be obtained. By utilizing this, a positive temperature characteristic can be given to the reference voltage.
Furthermore, since the temperature corrector 12 is arranged in the vicinity of the feedback control unit 3, by correcting the temperature characteristic according to the temperature in the vicinity of the feedback control unit 3 that tends to have a relatively strong negative temperature characteristic, A good correction result can be obtained.

(Second embodiment)
FIG. 5 shows a second embodiment of the present invention. The same parts as those of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted. Hereinafter, different parts will be described. The second embodiment shows a different configuration example of the temperature corrector. In FIG. 5A, the temperature corrector 31 (temperature correction circuit, current supply circuit) includes a plurality (n) of current supply units 34 configured by a combination of a constant current source 32 and a switch circuit 33. It is configured.

  FIG. 5B shows a specific configuration example of the switch circuit 33. The switch circuit 33 includes a series circuit of a constant current source 35 and a diode D2 connected between the power supply V3 and the ground, and a resistance element 36 connected between the power supply voltage VBG generated by the BGR circuit and the ground. And 37, an operational amplifier OP2 having an inverting input terminal connected to the former common connection point, and a non-inverting input terminal connected to the latter common connection point, and an NPN transistor having a base connected to the output terminal of the operational amplifier OP2. It is composed of TR1. The collector (terminal A) of the transistor TR1 is connected to the constant current source 32, and the emitter (terminal B) is connected to the non-inverting input terminal of the operational amplifier OP1.

  Next, the operation of the second embodiment will be described. In the switch circuit 33, the potential Vth3 of the non-inverting input terminal of the operational amplifier OP2 is substantially constant because it is a divided potential of the power supply voltage VBG having no temperature characteristics. On the other hand, since the potential Vth4 of the inverting input terminal is the forward voltage Vf of the diode D2, it has a negative temperature characteristic and decreases as the temperature increases.

  Therefore, if Vth3 <Vth4 when the temperature is low, the output signal of the operational amplifier OP2 is at a low level and the switch is turned off, so that the current from the constant current source 32 is applied to the non-inverting input terminal of the operational amplifier OP1. Does not flow. If the forward voltage Vf decreases as the temperature rises and Vth3> Vth4, the output signal of the operational amplifier OP2 becomes high level and the switch is turned on, so that the current from the constant current source 32 is It flows into the non-inverting input terminal of the operational amplifier OP1. That is, since the diode D2 corresponds to the temperature detector, the diode D2 is arranged in the vicinity of the feedback control unit 3 as in the diode D1 of the first embodiment.

  Therefore, by changing the voltage dividing ratio of the resistance elements 36 and 37 in each switch circuit 33 for the plurality of current supply units 34 (1 to n), the switches of the current supply units 34 (1 to n) are increased as the temperature rises. If the circuit 33 is set to be sequentially turned on, the amount of current supplied to the non-inverting input terminal of the operational amplifier OP1 can be gradually increased, and the comparison reference voltage Vth1 can be increased.

  As described above, according to the second embodiment, the temperature correction circuit 31 is configured to increase the current supplied to the comparison reference voltage input terminal of the operational amplifier OP1 by the constant current source 32 in the process of increasing the detected temperature. Therefore, as in the first embodiment, as the temperature rises, the reference value Vth1 can be raised to raise the integrated value of the control command signal, and a positive temperature characteristic can be imparted to the PWM drive signal.

  The current supply unit 34 is configured to intermittently switch the switch circuit 33 inserted between the constant current source 32 and the non-inverting input terminal of the operational amplifier OP1 in accordance with a change in the forward voltage Vf of the temperature detection diode D2. Since the diode D2 changes the forward voltage Vf in accordance with the negative temperature characteristic according to the detected temperature, the switch circuit 33 is changed according to the temperature rise. The comparison reference voltage Vth1 can be raised by closing and supplying a current to the non-inverting input terminal of the operational amplifier OP1. Also in this case, since the diode D3 corresponds to the temperature detector, the diode D3 is arranged in the vicinity of the feedback control unit 3 as in the diode D1 of the first embodiment.

  Further, the switch circuit 33 of the current supply unit 34 is constituted by the transistor TR1, and the conduction control of the transistor TR1 is performed according to the result of the operational amplifier OP2 comparing the forward voltage Vf of the diode D2 with the reference voltage Vth3. As a result, when the temperature detected by the diode D2 rises and the forward voltage Vf falls, the transistor TR2 is turned on as a result of comparison with the reference voltage Vth3, and current is supplied to the non-inverting input terminal of the operational amplifier OP1. can do.

(Third embodiment)
FIG. 6 shows a third embodiment of the present invention. The temperature corrector 41 (temperature correction circuit, reference voltage generation circuit) of the third embodiment is obtained by replacing the resistor element R3 connected to the non-inverting input terminal of the operational amplifier OP1 with a diode D3. With this configuration, the potential of the non-inverting input terminal becomes (V1−Vf), and the comparison reference voltage Vth1 increases as the forward voltage Vf decreases according to the temperature detected by the diode D3.
As described above, according to the third embodiment, the temperature corrector 41 is constituted by the series circuit of the diode D3 and the resistance element R4 connected between the power source V1 and the ground, and thus has a negative temperature characteristic. By using the forward voltage Vf, a comparison reference voltage Vth1 having a positive temperature characteristic can be provided at the common connection point between the two.

The present invention is not limited to the embodiments described above and shown in the drawings, and the following modifications or expansions are possible.
The temperature corrector 12 and the like are not necessarily arranged near the feedback control unit 3 and may be arranged anywhere as long as the temperature of the circuit board can be detected.
In the second embodiment, only one current supply unit 34 may be arranged.
In the third embodiment, the resistor element R3 may be connected in parallel to the diode D3.
A P-channel MOSFET, a bipolar transistor, an IGBT, or the like may be used as the driving switching element. Further, the present invention may be applied to a low-side drive type drive device.

The figure which is 1st Example of this invention and shows the structure of a linear solenoid drive device. The figure which shows a temperature corrector with the specific structure of a D / V conversion circuit. Diagram showing a specific configuration example of the temperature detector Diagram explaining correction of temperature characteristics FIG. 3 equivalent view showing a second embodiment of the present invention. FIG. 3 equivalent view showing a third embodiment of the present invention. 1 equivalent diagram showing the prior art Diagram explaining circuit operation Diagram showing temperature characteristics of control current

Explanation of symbols

  In the drawing, 2 is a D / V conversion circuit (duty / voltage conversion circuit), 3 is a feedback control unit (command voltage generation circuit), 4 is a V / D conversion circuit (PWM drive signal generation circuit), and 6 is an N-channel MOSFET. (Drive switching element), 7 is a linear solenoid, 8 is a resistance element (current detection circuit), 10 is an I / V conversion circuit (current detection circuit), 11 is a drive device, and 12 is a temperature corrector (temperature correction circuit). , 15 is a constant current source (current supply circuit), 23 is a resistance element, 25 is a reference voltage generation circuit, 31 is a temperature corrector (temperature correction circuit, current supply circuit), 32 is a constant current source, 33 is a switch circuit, 34 is a current supply unit, 41 is a temperature corrector (temperature correction circuit, reference voltage generation circuit), D1 to D3 are diodes, R4 is a resistance element, OP1 and OP2 are operational amplifiers, and TR1 is a transistor. .

Claims (9)

In a linear solenoid drive device that PWM-controls a drive switching element connected in series with a linear solenoid between a power supply and a ground,
A duty / voltage conversion circuit for converting a control command signal given by PWM duty into a voltage signal from the outside;
A current detection circuit for detecting a current flowing through the linear solenoid by converting it into a voltage signal when the driving switching element is turned ON;
A command voltage generation circuit that generates a PWM command voltage according to a difference between the voltage signal converted by the duty / voltage conversion circuit and the voltage signal converted by the current detection circuit;
A PWM drive signal generation circuit that generates a PWM drive signal corresponding to the PWM command voltage and outputs the PWM drive signal to the drive switching element;
A linear solenoid comprising: a temperature correction circuit that detects a temperature of a circuit board on which each of the circuits is mounted, and corrects a temperature characteristic of the PWM drive signal according to the detection result. Drive device. In the duty / voltage conversion circuit, the temperature correction circuit supplies a current for increasing the reference voltage to a comparison reference voltage input terminal of an operational amplifier constituting an integration circuit that integrates the control command signal. With
2. The linear solenoid drive device according to claim 1, wherein in the current supply circuit, a reference voltage generation circuit for applying a reference voltage for determining the current value has a positive temperature characteristic.   3. The linear solenoid driving apparatus according to claim 2, wherein the reference voltage generating circuit is configured by a series circuit of a diode and a resistance element connected between a power source and a ground. In the duty / voltage conversion circuit, the temperature correction circuit supplies a current for increasing the reference voltage to a comparison reference voltage input terminal of an operational amplifier constituting an integration circuit that integrates the control command signal. Configured as
2. The linear solenoid drive device according to claim 1, wherein the current supply circuit increases an amount of current supplied to the comparison reference voltage input terminal in a process in which a detected temperature rises.   The current supply circuit includes a current source, a switch circuit inserted between the current source and the comparison reference voltage input terminal, and a temperature detection diode, and changes the forward voltage of the diode. 5. The linear solenoid driving device according to claim 4, further comprising one or more current supply units configured to control the switching of the switching circuit. The current supply unit comprises the switch circuit with a transistor,
6. The linear solenoid driving device according to claim 5, further comprising an operational amplifier that controls conduction of the transistor according to a comparison result between a forward voltage of the diode and a reference voltage.   The temperature correction circuit is configured as a reference voltage generation circuit that provides a comparison reference voltage having a positive temperature characteristic to an operational amplifier that constitutes an integration circuit that integrates the control command signal in the duty / voltage conversion circuit. The linear solenoid drive device according to claim 1, wherein   8. The linear solenoid driving device according to claim 7, wherein the reference voltage generating circuit is configured by a series circuit of a diode and a resistance element connected between a power source and a ground.   The linear solenoid drive device according to claim 1, wherein the temperature correction circuit is disposed in the vicinity of the command voltage generation circuit.

Images