JP2008218900A - Solenoid drive control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a multisystem solenoid by a simple structure. <P>SOLUTION: Current detecting circuits 8a and 8b detect currents flowing in a plurality of solenoids, and output signals indicating magnitudes of the currents. One of the signals outputted from the current detecting circuits 8a and 8b is outputted, and the switching of the outputted signal is performed and repeated at predetermined timing. An A-D converter 5 performs A-D conversion to the signal outputted from a monitor switching circuit 7 in a period from a time when the switching has been carried out to a time when the next switching is carried out in the monitor switching circuit 7 to obtain a monitoring value indicating the magnitude of the current flowing in the solenoid for a plurality of times. A CPU 1 controls the solenoid corresponding to the monitoring value using a plurality of monitoring values obtained by the A-D converter 5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solenoid drive control device, and more particularly to a solenoid drive control device that performs drive control of a plurality of solenoids.

Conventionally, there is a technique described in Patent Document 1 as a solenoid control device for driving a plurality of solenoids. In the solenoid control device described in Patent Document 1, the voltage value indicating the solenoid current of each system is detected at the same timing. That is, for example, when controlling two systems of solenoids, a voltage value indicating the first system solenoid current and a voltage value indicating the second system solenoid current are detected at the same timing. The detected voltage value of the first system is input to the AD conversion unit of the control unit. On the other hand, the voltage value of the second system is once held by the voltage holding circuit and then input to the AD conversion unit of the control unit. In the solenoid control device, the voltage value from each system is sequentially input to the AD conversion unit by shifting the timing at which the voltage value is input to the control unit by the voltage holding circuit. Accordingly, the solenoid control device can have one AD conversion unit even when controlling a plurality of solenoids.
JP-A-9-283332

  The solenoid control device performs feedback control on the solenoid according to a detection result by detecting a solenoid current synchronized with an on timing of a pulse signal for driving the solenoid. Therefore, in the above solenoid control device, it is necessary to detect the solenoid current at the same timing in each system, and thus a voltage holding circuit is required. In the above solenoid control device, a voltage holding circuit is required instead of having one AD converter, so that the number of circuit components, the mounting area, and the cost can be sufficiently reduced. I could not.

  Therefore, an object of the present invention is to provide a solenoid drive control device capable of controlling a plurality of solenoids with a simple configuration.

  The present invention employs the following configuration in order to solve the above problems. That is, the first invention is a solenoid drive control device for controlling a plurality of solenoids. The solenoid drive control device includes a current detection unit, a switching unit, an A / D conversion unit, and a control unit. The current detection unit detects currents flowing through the plurality of solenoids, and outputs signals indicating the magnitudes of the currents. The switching unit outputs any one of the signals output from the current detection unit, and switches the output signal at the predetermined timing according to a control command input before the predetermined timing. Repeat. The A / D conversion unit performs A / D conversion on a signal output from the switching unit between the time when the switching unit performs switching and the time when the next switching is performed. Get the monitor value indicating the number of times. The control unit controls the solenoid corresponding to the monitor value using the plurality of monitor values acquired by the A / D conversion unit.

  In the second invention, the switching unit switches the signal to be output after the monitor value is acquired a plurality of times by the A / D conversion unit and before the control calculation by the control unit is executed. Also good.

  In the third invention, the A / D conversion unit starts acquiring the monitor value after the control unit completes the control calculation based on the previously acquired monitor value.

  In a fourth aspect of the invention, the solenoid drive control device includes: a power supply voltage detection unit that detects a power supply voltage supplied to the plurality of solenoids; and if the detected power supply voltage falls below a predetermined value, You may further provide the selection part which selects the solenoid which should be restarted. At this time, the control unit performs control to activate the solenoid selected by the selection unit.

  In a fifth aspect, the solenoid drive control device may further include a power supply voltage detection unit that detects a power supply voltage supplied to the plurality of solenoids. At this time, the control unit performs control to activate a plurality of solenoids when the detected power supply voltage falls below a predetermined value.

  In the sixth invention, the control unit may calculate an average value of a plurality of monitor values acquired by the A / D conversion unit and control the solenoid so that the average value approaches a predetermined target value. .

  According to the first aspect of the invention, the solenoid to be monitored is switched and A / D conversion is performed by the switching unit, so that the number of A / D converters used for monitoring the solenoid current can be reduced to one. Further, since the solenoid current is monitored a plurality of times and the control is performed based on a plurality of monitor values, it is not necessary to monitor a plurality of solenoids at the same timing. Therefore, even when monitoring is performed by switching the monitoring target, the voltage holding circuit is not necessary, and the configuration of the solenoid drive control device can be simplified.

  According to the second aspect of the present invention, since there is a time lapse between the switching in the switching unit and the solenoid current monitoring operation being performed, an accurate solenoid current value can be obtained after the output of the switching unit is stabilized. Obtainable.

  According to the third invention, the control calculation is performed by the control unit after the switching is performed in the switching unit, and the solenoid current monitoring operation is performed after the completion of the control calculation. This makes it more reliable to obtain an accurate solenoid current value after the output of the switching unit is stabilized.

  According to the fourth and fifth inventions, even when the solenoid power supply is lowered for some reason, it is possible to return the solenoid to the on state and drive the solenoid normally.

  According to the sixth aspect of the invention, since the control is performed based on the average current flowing through the solenoid, the solenoid can be controlled with high accuracy.

Hereinafter, a solenoid drive control device according to an embodiment of the present invention will be described. FIG. 1 is a diagram illustrating a configuration of a solenoid drive control device according to the present embodiment. As shown in FIG. 1, the solenoid drive control device includes a CPU 1, an input / output circuit 6, a first solenoid 11a, and a second solenoid 11b. The solenoid drive control device detects a solenoid current for two systems (two channels), that is, two solenoids 11a and 11b, and performs feedback control based on the detection result. The solenoid drive control device is mounted on, for example, a vehicle, and the solenoid is used as a valve for vehicle control. Further, in the present embodiment, a case where two solenoids are controlled will be described as an example, but the present invention can also be applied to a case where three or more solenoids are controlled. Details of the configuration of each unit will be described below.

  The CPU 1 performs a calculation process necessary for controlling the solenoids 11a and 11b. Specifically, the CPU 1 includes a first output circuit 2a, a second output circuit 2b, a SIO (Serial Input / Output) 3, a first A / D converter 4, and a second A / D converter 5. In the present embodiment, the second A / D converter 5 corresponds to the A / D conversion unit described in the claims, and the CPU 1 that performs a control calculation operation (steps S14 to S19 shown in FIG. 4) described later is described in the claims. It corresponds to the control part. The input / output circuit 6 detects the solenoid currents of the solenoids 11a and 11b and outputs them to the CPU 1, and controls the driving of the solenoids 11a and 11b according to a control signal (pulse signal) from the CPU 1. The input / output circuit 6 includes a monitor switching circuit 7, a first current detection circuit 8a, a second current detection circuit 8b, a first transistor 9a, a second transistor 9b, a first diode 10a, and a second diode 10b. In the present embodiment, each of the current detection circuits 8a and 8b corresponds to the current detection unit recited in the claims, and the monitor switching circuit 7 corresponds to the switching unit recited in the claims.

  The first output circuit 2a is a circuit that outputs a pulse signal for PWM control. The first output circuit 2a is connected to the base terminal of the first transistor 9a. The first transistor 9a is an NPN transistor, the collector terminal is connected to a solenoid power source (BS), and the emitter terminal is connected to one end of the first solenoid 11a. The first transistor 9a is a switch for turning on / off the current flowing through the first solenoid 11a in accordance with the pulse signal from the first output circuit 2a. The other end of the first solenoid 11a is connected to one input end of the first current detection circuit 8a. The first current detection circuit 8a is a circuit that detects a current (solenoid current) flowing through the first solenoid 11a. The other input terminal of the first current detection circuit 8a is grounded. A first diode 10a is connected to both ends of the first solenoid 11a. Specifically, a cathode terminal is connected between the first solenoid 11a and the first transistor 9a, and the first solenoid 11a An anode terminal is connected to the first current detection circuit 8a. The first diode 10a is for protecting the first transistor 9a from being destroyed by a voltage generated across the first solenoid 11a when the switch by the first transistor 9a is turned off.

  The second output circuit 2b is a circuit that outputs a pulse signal for PWM control. The second output circuit 2b is connected to the base terminal of the second transistor 9b. The second transistor 9b is an NPN transistor, the collector terminal is connected to a solenoid power source (BS), and the emitter terminal is connected to one end of the second solenoid 11b. The second transistor 9b is a switch for turning on / off the current flowing through the second solenoid 11b in accordance with the pulse signal from the second output circuit 2b. The other end of the second solenoid 11b is connected to one input end of the second current detection circuit 8b. The second current detection circuit 8b is a circuit that detects a current (solenoid current) flowing through the second solenoid 11b. The other input terminal of the second current detection circuit 8b is grounded. A second diode 10b is connected to both ends of the second solenoid 11b. Specifically, a cathode terminal is connected between the second solenoid 11b and the second transistor 9b, and the second solenoid 11b An anode terminal is connected to the second current detection circuit 8b. The second diode 10b is for protecting the second transistor 9b from being destroyed by the voltage across the second solenoid 11b generated when the switch by the second transistor 9b is turned off.

Each of the current detection circuits 8 a and 8 b outputs a voltage value (signal) indicating the detected solenoid current to the monitor switching circuit 7. The monitor switching circuit 7 is connected to the SIO 3 and the second A / D converter 5. The monitor switching circuit 7 selectively outputs a signal input from one of the current detection circuits 8 a and 8 b to the second A / D converter 5 in accordance with a switching command from the SIO 3. On the other hand, the first A / D converter 4 is connected to a solenoid power source (BS) and inputs a voltage value of the solenoid power source. Here, the solenoid power supply is supplied from, for example, a vehicle battery.

  Next, the operation of the solenoid drive control device shown in FIG. 1 will be described. FIG. 2 is a diagram for explaining the outline of the operation of the solenoid drive control device. Here, the operation of the solenoid drive control device is roughly divided into four types: (a) solenoid current monitoring operation, (b) monitoring target switching operation, (c) control calculation operation, and (d) power supply voltage monitoring operation. .

  As shown in FIG. 2, the solenoid drive control device has a control period between a period for controlling the first solenoid 11a (first channel control period) and a period for controlling the second solenoid 11b (second channel control period). Separately, the two solenoids 11a and 11b are controlled separately in a time division manner. In each control period, (a) solenoid current monitoring operation, (b) monitoring target switching operation, and (c) control calculation operation are sequentially performed. In addition, (d) the power supply voltage monitoring operation is performed at predetermined time intervals.

  (A) The solenoid current monitoring operation is an operation in which the CPU 1 monitors (acquires) the current flowing through the controlled solenoid. Although detailed operation will be described later, in the first channel control period, the CPU 1 acquires a value indicating a current flowing through the first solenoid 11a as a monitor value. In the second channel control period, the CPU 1 acquires a value indicating the current flowing through the second solenoid 11b as a monitor value. Further, in one solenoid current monitoring operation, the solenoid current is monitored a plurality of times. That is, in one solenoid current monitoring operation, the CPU 1 acquires the monitor value a plurality of times.

  When the plurality of times of monitoring are finished and the solenoid current monitoring operation is finished, the solenoid drive control device performs (b) a monitoring target switching operation. The monitoring target switching operation is an operation for switching a solenoid to be monitored. Specifically, in the first channel control period, the solenoid to be monitored is switched from the first solenoid 11a to the second solenoid 11b. In the second channel control period, the monitored solenoid is switched from the second solenoid 11b to the first solenoid 11a.

  (B) When the monitoring target switching operation ends, the solenoid drive control device performs (c) a control calculation operation. The control calculation operation is an operation for performing a calculation for controlling the solenoid to be controlled based on the monitor value acquired by the (a) solenoid current monitoring operation. Although detailed operation will be described later, the CPU 1 calculates a value (specifically, an average value of the monitor values) determined based on a plurality of monitor values acquired by the monitor operation. Then, calculation for controlling the solenoid to be controlled is performed based on the calculated value. Thus, a pulse signal corresponding to the calculation result is output from the first or second output circuit 2a or 2b. After the above control calculation operation is completed, one control period ends.

  When the control period of a certain channel ends, the control period of another channel starts. In the control period of other channels, (a) solenoid current monitoring operation, (b) monitoring target switching operation, and (c) control calculation operation are performed in order as described above. Therefore, the monitor switching circuit 7 repeatedly performs the monitoring target switching operation. Further, the solenoid current monitoring operation is performed between the monitoring target switching operation and the next monitoring target switching operation, so that the second A / D converter 5 is switched by the monitor switching circuit 7. The monitor value is acquired a plurality of times during the period from the start to the next switching. The CPU 1 controls the solenoids of a plurality of channels by repeatedly performing the processing in the control period in order for each channel. In the present embodiment, as shown in FIG. 2, the first channel control period for controlling the first solenoid 11a and the second channel control period for controlling the second solenoid 11b are repeated.

  In addition to the operations (a) to (c) described above, the solenoid drive control device (d) performs a power supply voltage monitoring operation. The power supply voltage monitoring operation is an operation for detecting the voltage of the solenoid power supply (BS) and determining whether it is necessary to restart each solenoid when the voltage falls below a predetermined value. The power supply voltage monitoring operation is performed once per predetermined time. Although details will be described later, even when the solenoid is turned off due to a drop in the solenoid power supply voltage by the power supply voltage monitoring operation, it can be restored to normal by restarting the solenoid.

  As described above, in the present embodiment, the monitoring target (control target) is switched using the switching circuit. As a result, the number of A / D converters used for monitoring the solenoid current can be reduced to one, so that the configuration of the solenoid drive control device can be simplified.

  Furthermore, in this embodiment, the solenoid current is monitored a plurality of times in the current monitoring operation, and the solenoid is controlled with high accuracy by performing the control based on the plurality of monitor values. Therefore, according to the present embodiment, it is not necessary to monitor a plurality of solenoids at the same timing and detect a solenoid current synchronized with the ON timing of the pulse signal, and it is sufficient to monitor each solenoid at a separate timing. Therefore, even when the monitoring target (control target) is switched by the switching circuit, the voltage holding circuit is not necessary, and the configuration of the solenoid drive control device can be simplified.

  Next, the details of the operation of the solenoid drive control device will be described with reference to FIGS. First, the above (d) power supply voltage monitoring operation will be described with reference to FIG. FIG. 3 is a flowchart showing a processing flow of the power supply voltage monitoring operation. The process shown in FIG. 3 does not need to be performed in synchronization with the operations (a) to (c) above, regardless of whether the control period is the first channel control period or the second channel control period. It is executed at a rate of once per predetermined time. The power supply voltage monitoring operation is preferably executed at least once during the monitoring operation period and the control operation operation period (see FIG. 2).

  First, in step S1, the CPU 1 detects a solenoid power supply voltage. Specifically, the first A / D converter 4 inputs the voltage value of the solenoid power supply and performs A / D conversion. In the present embodiment, the CPU 1 that executes step S11 corresponds to the power supply voltage detector described in the claims. In subsequent step S2, CPU 1 determines whether or not the digital value obtained in step S1 is smaller than a predetermined value. If the determination result of step S2 is affirmative, the processes of steps S3 and S4 are executed. On the other hand, if the determination result of step S2 is negative, the processes of steps S3 and S4 are skipped, and the CPU 1 ends the process shown in FIG.

In step S3, the CPU 1 selects a solenoid that needs to be recovered (restarted) from the solenoids 11a and 11b. Here, the solenoids 11a and 11b may have different values of the minimum holding current (current that can maintain the ON state). Therefore, the CPU 1 selects a solenoid that needs to be recovered by executing the following processing for each solenoid. That is, the CPU 1 calculates an estimated value of the current flowing through the solenoid based on the solenoid power supply voltage and the resistance of the solenoid detected in step S1. The estimated value is obtained by dividing the solenoid power supply voltage by the solenoid resistance. Note that the resistance value of each solenoid is stored in advance in a storage means inside or outside the CPU 1. Next, the CPU 1 determines whether or not recovery is necessary based on the estimated value and the minimum holding current of the solenoid. Specifically, when the estimated value is equal to or higher than the minimum holding current of the solenoid, it is determined that the solenoid does not require recovery, and when the estimated value is smaller than the minimum holding current of the solenoid, the solenoid is recovered. Judge that it is necessary. In the present embodiment, the CPU 1 that executes step S13 corresponds to the selection unit described in the claims.

  In subsequent step S4, CPU 1 sets the recovery flag to ON for the solenoid selected in step S3. Here, the recovery flag is a flag indicating whether or not the solenoid needs to be recovered, and one is set for each solenoid. The CPU 1 stores on / off of each recovery flag in the storage means. After the process of step S4, the CPU 1 ends the process shown in FIG.

  Next, the operations (a) to (c) will be described with reference to FIG. FIG. 4 is a flowchart showing the flow of processing of the solenoid current monitoring operation, the monitoring target switching operation, and the control calculation operation. The process shown in FIG. 4 is a process executed in one control period.

  First, the CPU 1 executes the processes of steps S11 and S12 as a solenoid current monitoring operation. That is, in step S11, the CPU 1 monitors the solenoid current of the solenoid to be controlled. Specifically, a voltage value indicating the solenoid current detected by the first or second current detection circuit 8 a or 8 b is input to the second A / D converter 5 via the monitor switching circuit 7. The second A / D converter 5 obtains a digital value (monitor value) indicating the magnitude of the solenoid current by A / D converting the input voltage value.

  In subsequent step S12, CPU 1 determines whether or not the solenoid current has been monitored a predetermined number of times. If the determination result in step S12 is affirmative, the process of step S13 described later is executed. On the other hand, when the determination result in step S12 is negative, the process of step S11 is executed again. That is, the CPU 1 repeats the processing loop of steps S11 and S12 until the solenoid current is monitored a predetermined number of times. When a predetermined number of monitor values are obtained, the process of (b) monitoring target switching operation (step S13) is executed.

  In addition, when performing PWM control with respect to a solenoid by a pulse signal, the time change of solenoid current becomes a triangular wave. The process of step S11 is executed so that the period for acquiring the monitor value from the signal from the monitor switching circuit 7 a plurality of times (that is, the period for executing step S11 a plurality of times) is different from the period of the triangular wave. It is preferred that If the monitor value acquisition period and the triangular wave period coincide, the multiple monitor values become current values (same values) in the same phase of the triangular wave, and the average value of the current cannot be calculated accurately. is there. The monitor value may be acquired three times or more so that a current value near the maximum value of the triangular wave, a current value near the minimum value, and a current value near the middle between the maximum value and the minimum value can be acquired. preferable.

  In step S13, the CPU 1 performs a monitoring target switching operation. Specifically, the SIO 3 of the CPU 1 outputs an output signal switching instruction to the monitor switching circuit 7. The switching instruction is an instruction to switch a signal to be output between a signal input from the first current detection circuit 8a and a signal input from the second current detection circuit 8b. In this embodiment, since there are two solenoids, the switching instruction may be a signal indicating “0” or “1”. Specifically, when the monitor switching circuit 7 outputs a signal input from the first current detection circuit 8 a, a switching instruction indicating “0” is output from the SIO 3. On the other hand, when the monitor switching circuit 7 outputs a signal input from the second current detection circuit 8b, a switching instruction indicating “1” is output from the SIO3. Therefore, in the first channel control period, SIO3 outputs a signal indicating “1” to the monitor switching circuit 7, and in the second channel control period, SIO3 outputs a signal indicating “0” to the monitor switching circuit 7. The monitor switching circuit 7 that has received the switching instruction switches the signal to be output in accordance with the switching instruction.

  After step S13, the processes of steps S14 to S19 are executed as (c) control calculation operation. First, in step S14, the CPU 1 calculates the average current of the solenoid during the monitoring period. The average current can be obtained by calculating the average of a plurality of monitor values obtained in step S11.

  In subsequent step S15, CPU 1 determines whether or not the recovery flag corresponding to the solenoid to be controlled is set to ON. The determination process in step S15 is a process for determining whether recovery is necessary for the solenoid to be controlled. If the determination result of step S15 is affirmative, the process of step S16 is executed. On the other hand, when the determination result of step S15 is negative, the process of step S17 is executed.

  In step S16, the CPU 1 sets the target current as the starting current. This starting current is the starting current of the solenoid to be controlled, and the CPU 1 stores the starting current value of each solenoid in the storage means in advance. On the other hand, in step S17, the CPU 1 sets the target current to a predetermined holding current. This holding current is the holding current of the solenoid to be controlled, and the CPU 1 stores the value of the holding current of each solenoid in the storage means in advance.

  As shown in step S16, when recovery is required for the solenoid to be controlled (Yes in step S15), the target current is set to the starting current. As a result, the starting current is applied to the solenoid by the processing of steps S18 and S19 described later, and the solenoid can be turned on. On the other hand, as shown in step S17 above, when recovery is not necessary for the solenoid to be controlled (No in step S15), the target current is set to the holding current, and normal control is performed on the solenoid in the on state. Following step S16 or S17, the process of step S18 is executed.

  In step S18, the CPU 1 performs a calculation for controlling the solenoid to be controlled. Specifically, the duty ratio of the pulse signal to be output is calculated based on the average current calculated in step S14 and the target current set in step S16 or S17. More specifically, the duty ratio of the pulse signal is calculated so that the average current approaches the target current.

  In the subsequent step S19, the CPU 1 outputs a pulse signal corresponding to the calculation result in step S18. That is, the first or second output circuit 2a or 2b of the CPU 1 outputs a pulse signal having the duty ratio calculated in step S18. By inputting this pulse signal to the first or second transistor 9a or 9b, the current flowing from the solenoid power source BS to the first or second solenoid 11a or 11b is controlled, and the driving of the solenoid is controlled. Each output circuit 2a and 2b continues to output a pulse signal having the same duty ratio after step S19 until a pulse signal is output in the next relevant control period. The frequency of the pulse signal is preferably set to several kHz or more for the purpose of reducing the current ripple to improve the controllability of the valve or reducing the solenoid driving sound. After step S19, the CPU 1 ends the process shown in FIG.

As described above, according to the process shown in FIG. 4, a plurality of monitor values are acquired by one solenoid current monitoring operation (steps S11 and S12), and an average current of the solenoid is calculated from the plurality of monitor values ( Step S14), control based on the average current is performed (steps S18 and S19). Therefore, it is not necessary to monitor the solenoid current of each solenoid at the same timing in synchronization with the ON timing of the pulse signal. Therefore, even when switching the monitoring target, no voltage holding circuit is required, and solenoid drive control is performed with a simple configuration. An apparatus can be realized.

  In this embodiment, after the solenoid current monitoring operation (steps S11 and S12), the monitoring target switching operation (step S13) is performed before the control calculation operation (steps S14 to S19) is performed. According to this, the control calculation operation is performed after the monitoring target switching operation is performed in a certain control period until the solenoid current monitoring operation is performed in the next control period. Here, immediately after the monitoring target switching operation is performed, the output of the monitor switching circuit 7 may not be stable, and an accurate solenoid current value may not be obtained. On the other hand, according to this embodiment, since there is a time margin between the monitoring target switching operation and the next solenoid current monitoring operation, the output of the monitor switching circuit 7 is stabilized. After that, an accurate solenoid current value can be obtained.

  In this embodiment, the next solenoid current monitoring operation is not performed until the control calculation operation is completed, but in other embodiments, the control calculation (after the control calculation operation is started) is performed. The next solenoid current monitoring operation may be performed before the operation is completed. For example, if the average current is calculated in step S14, the data indicating the plurality of monitor values stored in the storage unit may be updated to the content indicating the new monitor value. The next solenoid current monitoring operation may be started later.

  Further, according to the processing shown in FIGS. 3 and 4, even if the solenoid power supply voltage is lowered for some reason, the solenoid can be returned to the ON state. Details will be described below with reference to FIG.

  FIG. 5 is a timing chart showing a time change of a signal in each part of the solenoid drive control device. Hereinafter, with reference to FIG. 5, for example, an operation when the solenoid power supply voltage is lowered for some reason during the first channel control period will be described. The monitoring period shown in FIG. 5 is a period during the solenoid current monitoring operation.

  In FIG. 5, it is assumed that the power supply voltage SV falls below a predetermined voltage v during a period other than the monitoring period in the first channel control period. As a result, it is assumed that the solenoid current SA1 of the first solenoid 11a is lower than the minimum holding current Ik1, and the solenoid current SA2 of the second solenoid 11b is lower than the minimum holding current Ik2. At this time, as indicated by S1 indicating ON / OFF of the first solenoid 11a and S2 indicating ON / OFF of the second solenoid 11b, the first and second solenoids 11a and 11b are changed to the OFF state.

  In the present embodiment, a power supply voltage monitoring operation is performed, and when the power supply voltage SV falls below a predetermined voltage v, a process for estimating a solenoid current is performed, and a solenoid that needs to be recovered is selected (step S3). . As a result, in the example shown in FIG. 5, it is determined that both the first and second solenoids 11a and 11b need to be recovered.

  For the solenoid that is determined to require recovery, recovery control (control to activate the solenoid) is performed in the next control period of the solenoid. In the example shown in FIG. 5, if the process of step S15 is executed before the process of step S4 during the first channel control period, recovery control is not performed during this control period, and the next first Recovery control is performed during the channel control period. When the process of step S4 is performed before the process of step S15, recovery control is performed during the first channel control period in which the power supply voltage SV is lower than the predetermined voltage v.

When the recovery control is performed, the determination result in step S15 is affirmative, and the target current is set as the starting current in step S16. As a result, a pulse signal having a duty ratio D1 is output from the first output circuit 2a. The duty ratio D1 is larger than the minimum starting duty ratio Ds1 necessary for starting the first solenoid 11a. As a result, the current SA1 of the first solenoid 11a exceeds the minimum starting current Is1, and the first solenoid 11a is turned on (see FIG. 5).

  For the second solenoid 11b, recovery control is performed in the second channel control period that is performed next after the power supply voltage SV falls below the predetermined voltage v. When the recovery control is performed, the same control as the recovery control of the first solenoid 11a is performed. That is, a pulse signal having a duty ratio D2 larger than the minimum starting duty ratio Ds1 necessary for starting the second solenoid 11b is output from the second output circuit 2b. As a result, the current SA2 of the second solenoid 11b exceeds the minimum starting current Is2, and the second solenoid 11b is turned on (see FIG. 5).

  In the present embodiment, the CPU 1 only monitors the current flowing through one solenoid to be controlled during the monitoring period, and does not monitor the solenoid current during a period other than the monitoring period. That is, the CPU 1 does not monitor a plurality of solenoid currents at the same time. Therefore, when the solenoid power supply voltage (that is, the battery voltage) decreases for some reason, the CPU 1 cannot directly detect whether or not the solenoid is not monitoring the solenoid current at that time. . On the other hand, according to the processing shown in FIGS. 3 and 4, when the power supply voltage SV is lower than the predetermined voltage v, it is determined whether recovery is necessary for each solenoid. For the solenoid that is determined to require recovery, recovery control is performed in a control period that is performed thereafter. Therefore, even if the current of each solenoid is not monitored for the entire period, it is possible to reliably prevent the solenoid from being turned off and not operating. In recent years, the number of electric actuators mounted on vehicles has increased, and fluctuations in battery voltage have increased. Therefore, when the battery is a solenoid power source as in this embodiment, the processing shown in FIG. It is particularly effective.

  In the above embodiment, when the power supply voltage SV falls below the predetermined voltage v, it is determined whether recovery is necessary for each solenoid, and recovery control is performed only for the solenoid that is determined to require recovery. Here, in another embodiment, when the power supply voltage SV falls below a predetermined voltage v, recovery control may be performed for all solenoids. Specifically, in step S4 shown in FIG. 3, all recovery flags corresponding to the solenoids may be set to ON. At this time, the process of step S3 is not necessary, so that the process shown in FIG. 3 can be simplified and speeded up.

  Further, according to the present embodiment, as shown in FIG. 1, the input / output circuit 6 has the monitor switching circuit 7, and the CPU 1 switches the monitor switching circuit 7, thereby switching the monitoring target. Like to do. A communication path is also required between the CPU 1 and the input / output circuit 6 in order to transmit other control instructions, and it is preferable to transmit the switching instruction using this communication path. That is, it is preferable that the CPU 1 transmits the switching instruction through a communication path for transmitting another instruction transmitted from the CPU 1 to the input / output circuit 6. Thereby, the configuration of the present embodiment can be easily realized without forming a new communication path.

In the conventional method of monitoring the solenoid current in synchronization with the ON timing of the pulse signal, the processing load on the CPU 1 becomes too large, and it is difficult to increase the drive frequency of the PWM drive. For example, if the drive frequency is set to several kHz, the processing load on the CPU 1 becomes too large, and it is considered impractical in view of the CPU 1 performing other application processing. On the other hand, according to the present embodiment, since the average current of the solenoid is calculated from a plurality of monitor values, it is not necessary to monitor the solenoid current in exact synchronization with the pulse signal. Therefore, according to the present embodiment, the drive frequency can be increased, and the current ripple can be reduced by increasing the frequency of the pulse signal. By reducing the current ripple, the solenoid can be controlled with high accuracy and the solenoid driving sound can be reduced.

  The present invention can be used in, for example, a solenoid drive control device that performs drive control of a plurality of solenoids for the purpose of controlling a plurality of solenoids with a simple configuration.

The figure which shows the structure of the solenoid drive control apparatus which concerns on this embodiment. The figure for demonstrating the outline | summary of operation | movement of a solenoid drive control apparatus. Flow chart showing the flow of processing of power supply voltage monitoring operation Flow chart showing the flow of processing of solenoid current monitoring operation, monitoring target switching operation, and control calculation operation Timing chart showing time change of signal in each part of solenoid drive control device

Explanation of symbols

1 CPU
2a, 2b Output circuit 3 SIO
4 1st A / D converter 5 2nd A / D converter 6 I / O circuit 7 Monitor switching circuit 8a, 8b Current detection circuit 9a, 9b Transistor 10a, 10b Diode 11a, 11b Solenoid

Claims (6)

A solenoid drive control device for controlling a plurality of solenoids,
A current detector that detects currents flowing through the plurality of solenoids and outputs signals indicating the magnitudes of the currents;
Switching that outputs any one of the signals output from the current detection unit and repeatedly switches the output signal at the predetermined timing in accordance with a control command input before the predetermined timing. And
A monitor value indicating the magnitude of the current flowing through the solenoid by performing A / D conversion on the signal output from the switching unit between the switching unit and the next switching. An A / D converter that obtains a plurality of times,
A solenoid drive control device comprising: a control unit that controls a solenoid corresponding to the monitor value using a plurality of monitor values acquired by the A / D conversion unit.   The switching unit performs switching of a signal to be output after the monitor value is acquired by the A / D conversion unit a plurality of times and before the control calculation by the control unit is started. The solenoid drive control device described.   3. The solenoid drive control device according to claim 2, wherein the A / D conversion unit starts acquisition of a monitor value after the control unit completes a control calculation based on a monitor value acquired last time. A power supply voltage detector for detecting a power supply voltage supplied to the plurality of solenoids;
A selection unit that selects a solenoid to be restarted among the plurality of solenoids when the detected power supply voltage falls below a predetermined value;
The solenoid drive control device according to claim 1, wherein the control unit performs control to activate the solenoid selected by the selection unit. A power supply voltage detector for detecting a power supply voltage supplied to the plurality of solenoids;
2. The solenoid drive control device according to claim 1, wherein the control unit performs control to activate the plurality of solenoids when the detected power supply voltage falls below a predetermined value.   2. The control unit according to claim 1, wherein the control unit calculates an average value of a plurality of monitor values acquired by the A / D conversion unit, and controls the solenoid so that the average value approaches a predetermined target value. Solenoid drive control device.

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