JP2010206247A - Induction load controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction load controller capable of detecting and correcting the offset of the current detection portion of a load current without stopping the load current flowing to an induction load. <P>SOLUTION: The induction load controller includes a current detection circuit 12 for outputting the current detection value of the load current flowing to the induction load 30, a correction circuit 13 for outputting a corrected detection value for which the current detection value is corrected by reflecting the offset of the current detection circuit 12 on the current detection value, and a control circuit 14 for controlling the duty ratio of PWM signals for driving the induction load 30 on the basis of the corrected detection value so that the current value of the load current matches with the instruction value. The control circuit 14 switches a control system in the state that the current value of the load current is stable from closed loop control to open loop control for executing control so as to maintain the duty ratio controlled in the closed loop control, and the offset of the current detection circuit 12 is detected in the state of being switched to the open loop control. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inductive load control device including control means for controlling a duty ratio of a PWM signal for causing a load current to flow through an inductive load so that a current value of the load current flowing through the inductive load matches a target value.

  As a conventional technique, there is known a circuit that detects and corrects an offset of a current detection circuit by setting the input terminal of the current detection circuit to the same potential only when no current flows through the solenoid (for example, a patent) References 1 and 2).

JP 2006-87249 A JP 2003-31415 A

  However, since it may not be possible to stop the current flowing through the inductive load such as a solenoid, the above-described conventional technology accurately detects and corrects the offset of the current detection circuit in the case of such an inductive load. Can not do it.

  Therefore, an object of the present invention is to provide an inductive load control device that can detect and correct an offset of a current detector of a load current without stopping a load current flowing through the inductive load.

In order to achieve the above object, an inductive load control device according to the present invention comprises:
Current detection means for outputting a detection value corresponding to the current value of the load current flowing through the inductive load;
Correction means for outputting a corrected detection value obtained by correcting the detection value by reflecting the offset of the current detection means in the detection value;
Control means for controlling a duty ratio of a PWM signal for causing the load current to flow to the inductive load based on the correction detection value so that the current value of the load current matches the target current value of the load current; An inductive load control device comprising:
The control means uses a control method in a stable state in which the current value of the load current converges within a predetermined range, from a closed loop control in which the current value of the load current is detected by the current detection means by the current detection means. Switching to open loop control in which detection of the current value of the load current stops, and controlling to maintain the duty ratio controlled by the closed loop control by the open loop control,
The offset is detected in a state switched to the open loop control.

  According to the present invention, it is possible to detect and correct the offset of the current detector of the load current without stopping the load current flowing through the inductive load.

It is a block diagram of the inductive load control apparatus 100 which is the 1st Example of this invention. 4 is a time chart showing changes in the operating state of the inductive load control device 100. It is a block diagram of the inductive load control apparatus 200 which is 2nd Example of this invention. 5 is a time chart showing changes in the operating state of the inductive load control device 200. It is a block diagram of the inductive load control apparatus 300 which is the 3rd Example of this invention. 5 is a time chart showing changes in the operating state of the inductive load control device 300. It is a block diagram of the inductive load control apparatus 400 which is the 4th Example of this invention. 5 is a time chart showing changes in the operating state of the inductive load control device 400. It is a block diagram of the inductive load control apparatus 500 which is the 5th Example of this invention. 5 is a time chart showing changes in the operating state of the inductive load control device 500. 3 is a flow showing a method for detecting an offset of the current detection circuit 12; It is a block diagram of the inductive load control apparatus 600 which is the 6th Example of this invention.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of an inductive load control device 100 according to the first embodiment of the present invention. The inductive load control device 100 has, as main components, a linear solenoid 30, a PWM signal generation circuit 11, transistors 21, 22, a current detection circuit 12, a correction circuit 13, a control circuit 14, and a first switching. Unit 15 and a second switching unit 16. For example, the PWM signal generation circuit 11, the correction circuit 13, the control circuit 14, and the second switching unit 16 are configured in an arithmetic device such as a microcomputer. The PWM signal generation circuit 11, the current detection circuit 12, the correction circuit 13, the control circuit 14, the first switching unit 15, and the second switching unit 16 may be integrated. Each configuration will be described below.

  The linear solenoid 30 is an inductive load, and is an actuator in which a movable iron core is installed in a coil (inductor), and the movable iron core moves linearly by an electromagnetic force generated by flowing a current (solenoid current) through the coil. The linear solenoid 30 is a vehicle actuator and is used as an electronically controlled brake actuator. The linear solenoid 30 may be used as an actuator for a vehicle fuel injection valve. A reflux diode 31 is connected in parallel to the coil of the linear solenoid 30.

  The PWM signal generation circuit 11 generates a PWM signal for PWM driving the linear solenoid 30 as PWM signal generation means. Although described in detail later, the PWM signal is generated according to the duty ratio determined by the control circuit 14. The PWM signal corresponds to a switching signal for driving the transistor 21 as the first driving means.

  Further, the PWM signal generation circuit 11 outputs a drive signal for maintaining the transistor 22 as the second drive means in an ON state at the normal time. On the other hand, at the time of abnormality, the PWM signal generation circuit 11 may output a drive signal for turning off the transistor 22. Thereby, it is possible to prevent a current from flowing through the linear solenoid 30 when an abnormality occurs.

  The transistor 21 drives the linear solenoid 30. The transistors 21 and 22 are switching elements, and specific examples thereof include semiconductor elements such as IGBTs, MOSFETs, and bipolar transistors. The transistor 21 causes a current to flow through the linear solenoid 30 by switching according to the PWM signal generated by the PWM signal generation circuit 11. The upstream of the linear solenoid 30 is connected to the constant voltage source via the high-side transistor 21, and the downstream of the linear solenoid 30 is connected to the ground via the low-side transistor 22. This constant voltage source is, for example, a battery or a generator mounted on a vehicle (so-called + B power source). Further, the resistance in the ON state of the transistor 22 (that is, the ON resistance) corresponds to a detection resistance for detecting the current value of the solenoid current of the linear solenoid 30.

  Note that the linear solenoid 30 may be PWM-driven with the configuration shown in FIG. When the low-side transistor 22 performs switching according to the PWM signal generated by the PWM signal generation circuit 11, a solenoid current flows. The current value of the solenoid current is detected by the ON resistance of the transistor 21 maintained in the ON state by the PWM signal generation circuit 11.

  In FIG. 1, when the linear solenoid 30 is PWM driven, the transistor 22 may be replaced with a detection resistor for detecting the current value of the solenoid current of the linear solenoid 30. Similarly, in FIG. 12, the transistor 21 may be replaced with a detection resistor.

  Returning to FIG. 1, the current detection circuit 12 outputs a detection value corresponding to the current value of the solenoid current flowing through the linear solenoid 30 as current detection means. The current detection circuit 12 includes a differential input amplifier, for example. When an input voltage corresponding to the current value of the solenoid current is input to the differential input terminal, an output voltage corresponding to the current value of the solenoid current is output to the correction circuit 13. The current detection circuit 12 may incorporate an AD conversion circuit. In this case, for example, a digital output value corresponding to the current value of the solenoid current is output to the correction circuit 13.

  The correction circuit 13 outputs, as correction means, a corrected detection value obtained by correcting the detection value by reflecting the offset of the current detection circuit 12 in the detection value by the current detection circuit 12. The detection value output from the current detection circuit 12 includes a current detection error (that is, offset) of the current detection circuit 12 itself. In order to cancel the offset, the correction circuit 13 outputs a corrected detection value obtained by subtracting the offset from the detection value obtained by the current detection circuit 12 to the control circuit 14. A method for detecting the offset of the current detection circuit 12 will be described later.

  As a control means, the control circuit 14 sets the duty ratio of the PWM signal for flowing the solenoid current based on the correction detection value output from the correction circuit 13 so that the current value of the solenoid current matches the target value. Control. That is, the control circuit 14 executes PWM control for adjusting the duty ratio while keeping the fundamental frequency of the PWM signal for driving the transistor 21 constant. The control circuit 14 determines the ON time of the transistor 21 based on the correction detection value output from the correction circuit 13 so that the actual current value of the solenoid current matches the current instruction value that is the target value of the solenoid current. The duty ratio of the PWM signal is adjusted by setting the command value. When the transistor 21 is a P-channel, the transistor 21 is turned off when the PWM signal is at a high level, and turned on when the PWM signal is at a low level. When the current value of the solenoid current corresponding to the corrected detection value is larger than the current instruction value, the control circuit 14 changes the duty ratio largely by shortening the on-time command value, and the solenoid current corresponding to the corrected detection value. When the current value is smaller than the current instruction value, the duty ratio is changed to be small by increasing the command value of the on-time.

  The PWM signal generation circuit 11 generates a PWM signal (pulse signal) having a predetermined frequency according to the duty ratio calculated by the control circuit 14. The high level time and low level time of the PWM signal are determined by the duty ratio. The actual current value of the solenoid current increases when the transistor 21 is turned on and decreases when the transistor 21 is turned off. Note that the PWM signal generation circuit 11 may generate a PWM signal for driving the transistor 22 (see FIG. 12).

  In addition, the PWM signal generation circuit 11 causes the transistor 22 to output a PWM signal having a duty ratio of 100%, for example, so that the solenoid current can be always detected by the current detection circuit 12. As a result, the transistor 22 is always on.

  In this way, by performing the feedback control for adjusting the duty ratio of the PWM signal by setting the command value of the ON time of the transistor 21 based on the correction detection value output from the correction circuit 13, the solenoid current The actual current value of the solenoid current can be matched with the current instruction value which is the target value of the current value.

  By the way, in order to detect the offset of the current detection circuit 12, the two input terminals of the current detection circuit 12 need to have the same potential. However, when these input terminals are set to the same potential, the current value of the solenoid current is detected as “0”. Therefore, when the two input terminals of the current detection circuit 12 are simply set to the same potential in a state where the feedback control is performed as described above so that the deviation between the current instruction value and the actual current value becomes zero, the duty ratio Is adjusted to a small value, and the current value of the solenoid current increases rapidly. Therefore, the current value of the solenoid current cannot be adjusted accurately.

  Therefore, the control circuit 14 switches the control method in a stable state in which the actual current value of the solenoid current has converged within a predetermined range from closed loop control to open loop control. In the closed loop control, the current value is detected by the current detection circuit 12, and feedback for outputting the detected value of the solenoid current to the correction circuit 13 is performed. On the other hand, in the open loop control, the feedback of outputting the detected value of the solenoid current to the correction circuit 13 is not performed when the detection of the current value by the current detection circuit 12 is stopped. Then, before and after switching from closed loop control to open loop control, the control circuit 14 performs control so that the duty ratio controlled by the closed loop control immediately before switching is maintained by the open loop control immediately after switching. The correction circuit 13 detects the offset of the current detection circuit 12 in the state switched to the open loop control.

  Thus, the solenoid current is stopped from flowing by detecting the offset of the current detection circuit 12 in the state of switching to the open loop control for controlling to maintain the duty ratio controlled by the closed loop control immediately before the switching. Therefore, the offset can be detected and the current detection error due to the offset can be corrected. For example, when controlling the solenoid current that flows through a solenoid that has a constant current flow after power supply and that has almost no current change in a state other than the brake operating state, the duty ratio before switching is switched from closed loop control to open loop control. By detecting the offset while maintaining the offset, it is possible to increase the opportunity to detect and correct the offset without stopping the solenoid current. As a result, the accuracy of current detection can be improved.

  Here, the control circuit 14 performs switching between closed-loop control and open-loop control by switching the switching unit 15. The switching unit 15 can switch to closed loop control by switching the switches sw1 and sw2 to the on state and switching the switch sw3 to the off state. Conversely, the switching unit 15 can switch to the open loop control by switching the switches sw1 and sw2 to the off state and switching the switch sw3 to the on state. By turning on the switch sw3, the two input terminals of the current detection circuit 12 have the same potential.

  Further, the control circuit 14 switches the switching unit 16 in order to control the duty ratio controlled by the closed loop control before switching to be maintained by the open loop control after switching. The switching unit 16 may be a switch on software. In the case of closed-loop control, the switching unit 16 switches the switch sw4 to the on state and switches the switch sw5 to the off state, and thereby according to the corrected detection value corrected based on the latest current value detected by the current detection circuit 12. The calculated duty ratio is output to the PWM signal generation circuit 11. Thereby, feedback control which is closed loop control is executed. Conversely, in the case of open loop control, the switching unit 16 switches the switch sw4 to the off state and switches the switch sw5 to the on state, thereby changing the duty ratio controlled by the closed loop control before switching to the PWM signal generation circuit. 11 is output. Thereby, the pre-cycle duty control that is open loop control is executed.

  The control circuit 14 determines that the state where the difference between the current instruction value and the current value of the solenoid current corresponding to the corrected detection value is within a predetermined range is a stable state where the actual current value of the solenoid current has converged within the predetermined range. . The control circuit 14 that has been determined to be in the stable state outputs an offset detection signal in order to detect the offset. The switching units 15 and 16 perform the above switching operation according to the offset detection signal.

  FIG. 11 is a flowchart showing a method for detecting the offset of the current detection circuit 12. The current detection circuit 12 detects the current value of the solenoid current (step 10). The correction circuit 13 corrects the detection value detected by the current detection circuit 12 with the previously detected offset, and outputs a corrected detection value obtained by correcting the detection value detected by the current detection circuit 12 to the control circuit 14. (Step 20). The control circuit 14 performs closed loop control for controlling the duty ratio based on the correction detection value corrected this time (step 30). The control circuit 14 determines that the state where the difference between the current instruction value and the current value corresponding to the corrected detection value is within a predetermined range is a stable state where the actual current value of the solenoid current has converged within the predetermined range. If it is determined that the state is not stable, the process returns to step 10. The execution of the closed loop control is repeated until it is determined that the state is stable (steps 10 to 40). When determining that the control circuit 14 is in a stable state, the control circuit 14 switches the control method from closed loop control to open loop control (step 50). The control circuit 14 performs control so that the duty ratio controlled by the closed loop control before switching is maintained by the open loop control after switching. The correction circuit 13 detects the offset while being switched to the open loop control (step 60). After detecting the offset, the control circuit 14 switches from open loop control to closed loop control (step 70). After step 70, the process returns to step 10.

  FIG. 2 is a time chart showing changes in the operating state of the inductive load control device 100. After the current instruction value is changed at timing t0, the solenoid current starts to stabilize at timing t1. Switching from closed loop control to open loop control is performed at timing t3 when a predetermined time has elapsed from timing t1. Thereby, it is possible to prevent the control method from being switched in a state where the solenoid current is unstable, and to detect the offset in a state where the solenoid current is reliably stabilized. In the open loop control, it is preferable to maintain the duty ratio one cycle before that was controlled in the immediately preceding closed loop control. The duty ratio one cycle before corresponds to the duty ratio in the PWM period from timing t2 to t3. By controlling with the duty ratio of the immediately preceding cycle, it is possible to minimize the sudden change in the current value of the solenoid current even when switching to open loop control. The offset is detected in the state switched to the open loop control. The period during which the closed loop control is temporarily switched to the open loop control is one period of the PWM signal. After the offset is detected, the open loop control is switched to the closed loop control at timing t4. Therefore, the offset can be detected without stopping the solenoid current.

  It should be noted that the control method may be switched from the closed loop control to the open loop control in a stable state within a fixed time from the change point t0 of the current instruction value. If the control method is switched after the stable state continues for a while after the change time t0, the state in which the offset is not detected and corrected continues for a while, so that the current detection accuracy in that state is reduced. is there.

  FIG. 3 is a configuration diagram of the inductive load control device 200 according to the second embodiment of the present invention. The description of the same configurations and effects as those of the first embodiment is omitted. The inductive load control device 200 includes a temperature monitoring circuit 41, a temperature hold circuit 42, a temperature comparison circuit 43, and a detectability determination circuit 44.

  The temperature monitoring circuit 41 detects the temperature of the current detection circuit 12. The temperature hold circuit 42 stores the temperature detected by the temperature monitoring circuit 41. The temperature hold circuit 42 stores the temperature when the offset of the current detection circuit 12 is detected. The temperature comparison circuit 43 compares the current temperature detected by the temperature monitoring circuit 41 with the temperature at the past detection time of the offset held by the temperature hold circuit 42, and outputs the comparison result to the detectability determination circuit 44. To do. The detectability determination circuit 44 detects an offset when it is determined that the temperature of the current detection circuit 12 fluctuates by a predetermined temperature threshold or more from the previous detection time of the offset and the current value of the solenoid current is in a stable state. . The temperature threshold value for determining whether or not the offset can be detected may be determined according to the temperature characteristic of the offset of the current detection circuit 12 and the influence of the temperature characteristic on the drive system of the linear solenoid 30.

  As a result, an offset detection operation in consideration of the temperature characteristics of the offset of the current detection circuit 12 can be performed. If the current temperature of the current detection circuit 12 does not fluctuate significantly compared to the previous offset detection time, there is almost no current detection error due to the offset. Therefore, by limiting the number of offset detection operations depending on the temperature characteristics of the offset, unnecessary offset detection operations can be eliminated, and the brake control operation and the offset detection operation can be prevented from overlapping. .

  FIG. 4 is a time chart showing changes in the operating state of the inductive load control device 200. After the current instruction value is changed at the timing t0, the solenoid current starts to stabilize at the timing t1, and therefore the control circuit 14 outputs a signal A indicating the stable state to the detectability determination circuit 44. Although the current value is in a stable state at the timing t2, the offset detection is not performed at the timing t2 because the temperature fluctuation range from the temperature at the previous offset detection time of the current detection circuit 12 is small. At a timing t3 when the solenoid current is in a stable state and the temperature of the current detection circuit 12 fluctuates by a predetermined value or more, the detectability determination circuit 44 outputs an offset detection signal. Switching from closed loop control to open loop control is performed according to the offset detection signal. The offset is detected in a state where the control is switched to the open loop control that maintains the duty ratio of the previous cycle controlled by the closed loop control. After the offset is detected, the open loop control is switched to the closed loop control at timing t4. Therefore, as in the first embodiment, the offset can be detected without stopping the solenoid current.

  FIG. 5 is a configuration diagram of an inductive load control device 300 according to the third embodiment of the present invention. The description of the same configuration as in the first and second embodiments is omitted. The inductive load control device 300 includes a vehicle speed conversion circuit 51 and a detectability determination circuit 52.

  The vehicle speed conversion circuit 51 detects the current vehicle speed based on wheel speed pulses that change according to the traveling speed of the vehicle. When it is determined that the current vehicle speed is equal to or lower than a predetermined value and the current value of the solenoid current is in a stable state, the detectability determination circuit 52 detects an offset.

  When the brake control is operated at the time of detecting the offset, there is a possibility that the change in the brake hydraulic pressure accompanying the change in the solenoid current is delayed by the offset detection time. When the vehicle speed is high, the influence on the braking performance such as the stopping distance and behavior is large. Therefore, by performing the offset detection in a predetermined low speed state, it is possible to suppress a substantial influence on the braking performance such as the stopping distance and the behavior.

  FIG. 6 is a time chart showing changes in the operating state of the inductive load control device 300. After the current instruction value is changed at the timing t0, the solenoid current starts to stabilize at the timing t1, and therefore the control circuit 14 outputs a signal A indicating the stable state to the detectability determination circuit 52. Although the current value is in a stable state at the timing t2, the vehicle speed is fast, so that the offset is not detected at the timing t2. At a timing t3 when the solenoid current is in a stable state and a vehicle speed equal to or higher than a predetermined value is detected, the detection availability determination circuit 52 outputs an offset detection signal. Switching from closed loop control to open loop control is performed according to the offset detection signal. The offset is detected in a state where the control is switched to the open loop control that maintains the duty ratio of the previous cycle controlled by the closed loop control. After the offset is detected, the open loop control is switched to the closed loop control at timing t4. Therefore, as in the first and second embodiments, the offset can be detected without stopping the solenoid current.

  FIG. 7 is a configuration diagram of an inductive load control device 400 according to the fourth embodiment of the present invention. The description of the same configuration as in the first, second, and third embodiments is omitted. The inductive load control device 400 includes a detectability determination circuit 61 to which an accelerator pedal signal is input.

  When the accelerator operation of the driver is detected by the accelerator pedal signal and it is determined that the current value of the solenoid current is in a stable state, the detectability determination circuit 61 detects an offset.

  While the accelerator operation is being performed, it is considered that the brake operation is not being performed, and by adding that it is the period during which the accelerator operation is being performed to the permission condition for detecting the offset, the brake performance is improved. The offset can be corrected without affecting it. Since there is almost no change in the solenoid current due to the brake operation being performed, the offset can be accurately detected during a period when the solenoid current is stable. In particular, since the brake performance may be affected during the offset detection period even in the low speed state, the permission condition for detecting the offset between the low speed state and the accelerator operation being performed By adding to the above, the influence on the brake performance can be further suppressed and the offset can be corrected accurately.

  Also, the offset detection / correction time is sufficiently shorter than the time for the driver to switch from the accelerator to the brake, so it is within a predetermined time after the end of the accelerator operation on the vehicle and until the start of the brake operation on the vehicle. By adding the time (that is, the idling time after the end of the accelerator operation) to the permission condition for detecting the offset, the offset can be corrected without affecting the braking performance. . In particular, the brake performance may be affected during the offset detection period even in the low-speed state, so that the low-speed state and the above idle time are the permission conditions for detecting the offset. By adding, the influence on the brake performance can be further suppressed and the offset can be corrected.

  FIG. 8 is a time chart showing changes in the operating state of the inductive load control device 400. FIG. 8 is a time chart when the offset is detected based on the idle time. After the current instruction value is changed at the timing t0, the solenoid current starts to stabilize at the timing t1, and therefore the control circuit 14 outputs a signal A indicating the stable state to the detectability determination circuit 61. Although the current value is in a stable state at the timing t2, since the accelerator operation is turned off, the offset is not detected at the timing t2. At a timing t3 when the solenoid current is in a stable state and the accelerator operation is on, the detectability determination circuit 61 outputs an offset detection signal. Switching from closed loop control to open loop control is performed according to the offset detection signal. The offset is detected in a state where the control is switched to the open loop control that maintains the duty ratio of the previous cycle controlled by the closed loop control. After the offset is detected, the open loop control is switched to the closed loop control at timing t4. Therefore, as in the first, second, and third embodiments, the offset can be detected without stopping the solenoid current.

  FIG. 9 is a configuration diagram of an inductive load control device 500 according to the fifth embodiment of the present invention. The description of the same configuration as in the first to fourth embodiments is omitted. The inductive load control device 500 includes a + B power supply monitoring circuit 71.

  If the + B power supply voltage fluctuates during offset detection, the current flowing through the linear solenoid 30 fluctuates if the duty ratio is constant. That is, when the + B power supply voltage increases, the solenoid current increases, and when the + B power supply voltage decreases, the solenoid current decreases.

  Therefore, the + B power supply monitoring circuit 71 monitors the + B power supply voltage that is also the power supply voltage of the linear solenoid 30. The control circuit 14 finely adjusts the duty ratio in the open loop control according to the + B power supply voltage at the time of offset detection monitored by the + B power supply monitoring circuit 71. The control circuit 14 increases the duty ratio according to the increase of the + B power supply voltage at the time of detecting the offset, and decreases the duty ratio according to the decrease of the + B power supply voltage at the time of detecting the offset. Thereby, even if the + B power supply voltage fluctuates at the time of detecting the offset, the current fluctuation of the linear solenoid 30 can be suppressed.

  FIG. 10 is a time chart showing changes in the operating state of the inductive load control device 500. After the current instruction value is changed at timing t0, the solenoid current starts to stabilize at timing t1. Switching from closed loop control to open loop control is performed at timing t3 when a predetermined time has elapsed from timing t1. The offset is detected in a state where the control is switched to the open loop control that maintains the duty ratio of the previous cycle controlled by the closed loop control. Even if the + B power supply voltage decreases during the detection of the offset, the duty ratio is adjusted to be small, so that the solenoid current can be prevented from decreasing. After the offset is detected, the open loop control is switched to the closed loop control at timing t4. Therefore, as in the first to fourth embodiments, the offset can be detected without stopping the solenoid current.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, even in the embodiment in which the above-described embodiments are combined with each other, the offset can be accurately detected without stopping the solenoid current.

  Further, for example, by replacing the linear solenoid 30 with an inductive element (inductance element) and providing driving means for driving the inductive element according to a PWM signal, the inductive load control device of the above-described embodiment can be replaced with a converter, a switching power supply device, a motor It is also possible to apply as a control device.

DESCRIPTION OF SYMBOLS 11 PWM signal generation circuit 12 Current detection circuit 13 Correction circuit 14 Control circuit 15,16 Switching part 21,22 Transistor 30 Linear solenoid 31 Reflux diode

Claims (10)

Current detection means for outputting a detection value corresponding to the current value of the load current flowing through the inductive load;
Correction means for outputting a corrected detection value obtained by correcting the detection value by reflecting the offset of the current detection means in the detection value;
Control means for controlling a duty ratio of a PWM signal for causing the load current to flow to the inductive load based on the correction detection value so that the current value of the load current matches the target current value of the load current; An inductive load control device comprising:
The control means uses a control method in a stable state in which the current value of the load current converges within a predetermined range, from a closed loop control in which the current value of the load current is detected by the current detection means by the current detection means. Switching to open loop control in which detection of the current value of the load current stops, and controlling to maintain the duty ratio controlled by the closed loop control by the open loop control,
The inductive load control device, wherein the offset is detected in a state where the control is switched to the open loop control.   The inductive load control device according to claim 1, wherein the control means maintains a duty ratio of one cycle before controlled by the closed loop control by the open loop control.   3. The inductive load control device according to claim 1, wherein the control unit switches from the closed loop control to the open loop control in the stable state within a predetermined time from the change of the target current value.   The inductive load control device according to any one of claims 1 to 3, wherein the control means switches from the closed loop control to the open loop control when the stable state has elapsed for a predetermined time.   The inductive load control device according to any one of claims 1 to 4, wherein the control means switches from the open loop control to the closed loop control after the offset is detected. Temperature detecting means for detecting the temperature of the current detecting means,
The inductive load control device according to any one of claims 1 to 5, wherein the offset is detected when the temperature fluctuates by a predetermined value or more from a past detection time of the offset. Voltage detecting means for detecting the power supply voltage of the inductive load,
The inductive load control device according to any one of claims 1 to 6, wherein the control means adjusts a duty ratio in the open loop control according to the power supply voltage at the time of detecting the offset. The inductive load is a solenoid for a vehicle brake,
The inductive load control device according to any one of claims 1 to 7, wherein the offset is detected when a speed of the vehicle is equal to or less than a predetermined value. The inductive load is a solenoid for a vehicle brake,
9. The offset according to claim 1, wherein the offset is detected within a predetermined time after the end time of an accelerator operation on the vehicle and a time until a start time of a brake operation on the vehicle. Inductive load control device. The inductive load is a solenoid for a vehicle brake,
The inductive load control device according to any one of claims 1 to 8, wherein the offset is detected during an accelerator operation on the vehicle.