JP4508320B2 - Failure determination device for electromagnetic coil operating device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a failure determination device for an electromagnetic coil operating device.
[0002]
[Prior art]
For example, the determination of a short-circuit failure in an electromagnetic coil operating device is used for throttle electronic control for automobiles, and an H bridge circuit provided with a failure detection circuit as shown in FIG. 5 is known. In this electromagnetic coil operating device, both ends of a coil 1 for exciting and driving a throttle valve (not shown) are connected to a power supply connection line and a ground line, respectively, and FETs 9, 10, 11 and 12 are provided on each connection line. ing. By selecting these switching operations, the direction of the current supplied from the power supply connection line 16 to the coil 1 and the stop of the power feeding are controlled. For example, when the FETs 9 and 12 are turned on and the FETs 10 and 11 are turned off, a current flows in the direction of the arrow in the figure, and the driving direction of the throttle valve is reversed by selecting the reverse pattern.
[0003]
The FET 9 and FET 10 are connected to the operational amplification element 19 through connection lines of the resistors 17 and 18 to constitute a supply current detection circuit 20. The supply current detection circuit 20 detects the value of the current supplied to the FETs 9 and 10 from the voltage drop caused by the resistors 17 and 18. Further, the FET 11 and the FET 12 are connected to the operational amplification element 22 through a connection line with the resistor 21 to constitute an overcurrent detection circuit 23. The overcurrent detection circuit 23 detects the value of the current supplied to the FETs 11 and 12 from the voltage drop caused by the resistor 21.
[0004]
However, the H bridge circuit requires two detection circuits including a supply current detection circuit 20 and an overcurrent detection circuit 23, and a determination program for determining a short circuit based on a detected current value by a calculation means such as a CPU (not shown). The cost was high due to the complexity. There is also a problem that the temperature of semiconductor elements such as the CPU and FET in the vicinity thereof increases due to heat generated from the resistors 17, 18 and 21.
[0005]
In view of the above, the applicant of the present application has applied for a low-cost failure determination device that suppresses the temperature rise of the semiconductor element by using one detection circuit as shown in FIG. 6 (Japanese Patent Application No. 10-118219). ). In addition, in this type of electromagnetic coil operating device, an application has also been filed for a drive circuit capable of switching FETs 9 to 12 by PWM control and performing more stable and minute control (Japanese Patent Application No. 10-118219).
[0006]
The device shown in FIG. 6 is a failure determination device for an electromagnetic coil operating device that performs the PWM control. In this detection circuit, the coil 1 is a coil obtained from a connection point a on the negative side and a connection point b on the positive side. The potential at both ends is converted into a digital signal by the A / D converter 7 and is taken into an arithmetic means constituted by a CPU or the like. This calculation means switches the FETs 9 to 12 by a drive circuit (not shown), and inputs a PWM-controlled drive pulse to the coil 1 by arbitrarily selecting the switching state. This switching state can be indicated by a pulse train with a minute time interval, and FIG. 7 is a chart schematically showing this pulse train.
[0007]
As shown in FIG. 7, the A / D converter 7 starts input and conversion processing of the potential across the coil so as to synchronize with the drive pulse. The digital signal of the both-end potential is taken into the calculation means, and the calculation means executes a program for determining whether or not the potential is the both-end potential according to the switching state. For example, when the drive pulse that first appears in FIG. 7 is in a state where only the FETs 9 and 12 are ON, the potentials at both ends of the coil 1 are equal in a preferable energized state when the resistance values in the FET 9 and FET 12 are equal. . In this state, if the connection point a is shorted to GND, the sum of the potentials at both ends of the coil 1 becomes smaller than the power supply voltage. In this way, a short-circuit fault can be found by comparing the voltage signal that has been A / D converted for a predetermined time in synchronization with the drive pulse with the power supply voltage value.
[0008]
Note that such a short circuit determination is performed periodically or for an arbitrary pulse. Although the ground fault determination in the ON state of the coil 1 has been described here as an example, if a pulse in the OFF state of the coil 1 is seen in the pulse train, it is possible to determine a power fault that occurs due to a short circuit with the power supply line 16. Hereinafter, the ratio of the ON time in the target pulse modulated by the PWM control is referred to as the duty ratio (%) of the drive pulse . The time required for the drive ON process and the input process of the A / D converter 7 is referred to as a required time for the input process of the A / D converter.
[0009]
[Problems to be solved by the invention]
However, in the above-described PWM control type electromagnetic coil operating device, the potential signal is taken in via the A / D converter 7 in ON / OFF units in one pulse. A problem has arisen in the determination accuracy in relation to the duty ratio . For example, in the double integration type, the A / D converter 7 integrates an analog input voltage for a predetermined time, and counts the discharge time of the integrator by clock pulses. Therefore, the analog input voltage cannot be accurately captured with a pulse having a duty less than the required time such as the input processing for A / D conversion or the sampling time. In the present application, a duty equivalent to such a required time is referred to as a predetermined duty ratio .
[0010]
Specifically, in the PWM control method, the duty can be calculated by software, and the electromagnetic coil operation can be controlled with a small duty to improve the control characteristics. However, if the duty ratio of the drive pulse to be detected is smaller than the predetermined duty ratio , the A / D conversion value may not always be a true value. Therefore, when performing PWM driving, there is a problem that accurate short-circuit determination is not made in a region where the pulse input of the drive pulse having a duty ratio lower than a predetermined duty ratio is continued, and detection of a short-circuit failure is delayed. There is a fear. On the other hand, if the restriction that the duty ratio of the drive pulse is maintained at a predetermined duty ratio or more is provided, the controllability by PWM is sacrificed.
[0011]
The present invention, when the control duty ratio of the target pulse train falls below a predetermined duty ratio required for capturing the voltage value by the A / D conversion is performed, thereby allowing an accurate short-circuit determination, the control of the An object of the present invention is to provide a short-circuit determination device for an electromagnetic coil operating device in which the degree of freedom is not limited.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a failure determination apparatus for an electromagnetic coil operating device according to the present invention comprises an H bridge circuit in which both ends of an electromagnetic coil are connected to a power supply line and a ground line via a switch means, and the switch means. Drive means for selectively driving and PWM controlling the drive pulse input to the electromagnetic coil, and calculating the duty ratio of the drive pulse , and A / D conversion in synchronization with any of the drive pulses a comparison result between the power supply potential across potential and the power supply line of the electromagnetic coil taken from vessels, and determining operation means a short-circuit failure based on the selected state of the switch means driven by pulses the synchronizing , a failure judgment apparatus of an electromagnetic coil driving apparatus for chromatic and said calculating means, the duty ratio of the PWM controlled drive pulse, the a / D converter With a predetermined duty ratio to the time required for A / D conversion input processing same time and on-time, when included the driving pulse duty ratio less than the predetermined duty ratio to the drive pulse, by the drive means to the electromagnetic coil causes input drive pulses of the predetermined duty ratio, is characterized by determining the short-circuit failure had us when drive pulse input of the predetermined duty ratio.
[0013]
Further, in the calculation means, the duty ratio of the PWM-controlled drive pulse is compared with a predetermined duty ratio having an ON time that is the same as the time required for the A / D conversion input process of the A / D converter. When the number of pulses that do not satisfy the predetermined duty ratio is counted and the number of pulses reaches a predetermined value, the total value of the duty ratio of each drive pulse including the pulse having the predetermined duty ratio is not changed. As described above, by adjusting the duty ratio of each drive pulse, the predetermined duty ratio can be set to an arbitrary pulse in the drive pulse , and the short-circuit failure may be determined .
[0014]
Further, the calculating means, driving with inputting the pulse of the predetermined duty ratio in place of any pulse, the correction value obtained by subtracting the predetermined duty ratio from said arbitrary pulse is input to the subsequent It may be configured to perform correction processing to be added to the duty ratio of the pulse .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a short-circuit determination device according to the present embodiment. The outline of the configuration of the failure determination device is basically the same as that described above, and an H bridge circuit for energizing the coil 1 and a throttle control unit for controlling the coil 1 as an actuator via the H bridge circuit. It consists of two. The throttle control unit 2 includes a CPU 3 as a calculation means, a ROM 4 and a RAM 5, a drive circuit group 6 for PWM control of the coil 1, and an A / D converter 7. The data signal and address signal from the A / D converter 7 are input / output to / from the CPU 3.
[0016]
The drive means for inputting the drive pulse modulated by PWM to the coil 1 is connected to the control input terminals of the switching elements of the four FETs 9, 10, 11, 12 and the FETs 9 to 12 as switch means of the H bridge circuit. And a drive circuit group 6. A program for driving the drive circuit group 6 is recorded in the ROM 4. The coil 1 is PWM-controlled by causing the CPU 3 to execute this program. Further, the ROM 4 stores a program that can be read by the CPU 3 in order to execute processing based on flowcharts to be described later shown in FIGS.
[0017]
The A / D converter 7 of this embodiment and the H bridge circuit are connected as follows. The connection point a on the minus end side of the coil 1 and the connection point b on the plus end side thereof are connected at a connection point c via a resistor 13 and a resistor 14, respectively, and a predetermined voltage value is obtained from the connection point c. It is connected to the A / D converter 7 via a resistor 15 for changing to The A / D converter 7 is connected by a connection line drawn from the power supply line 16 and receives the power supply potential VB. The A / D converter 7 converts the input voltage from the connection point c and the input voltage from the power supply line 16 into digital signals, respectively, and then stores them in the RAM 5 as necessary. Further, the CPU 3 reads out and executes a short-circuit failure determination program from the ROM 4 based on these digital signals. For example, the short-circuit fault of the H bridge circuit is determined as follows. Note that the input resistance value of the A / D converter 7 is large, and the current value supplied to the A / D converter 7 can be ignored.
[0018]
Each of the FETs 9 to 12 has switching elements 9a to 12a and resistors 9b to 12b connected in series, and the resistance values are the same. In the on mode in which only the switching element 9a of the FET 9 and the FET 12 switching element 12a are turned on, the voltage applied to the connection point c is in the following state in a preferable state of the electromagnetic coil operating device. The voltage value VP at the connection point a is lower than the power supply voltage VB by the voltage across the resistor 9b, and the voltage value VN at the connection point b is higher than the ground potential by the voltage across the resistor 12b. Therefore, since the currents flowing through the resistors 9b and 12b are the same, the voltage value VP and the voltage value VN are equal. For example, in the case of a ground fault in which the connection line at the connection point a is short-circuited to GND, the current flowing through the resistor 9b increases, so that the voltage between both ends increases and the sum of VP and VN is smaller than the power supply voltage VB. Become. When this voltage value is detected via the A / D converter 7 and the sum of VP and VN is smaller than VB, the CPU 3 can determine that a ground fault has occurred.
[0019]
Further, in the off mode in which only the switching element 11a and the switching element 12a are ON, a current flows due to the inductance of the coil 1, and this current flows through a circuit extending from GND to the GND via the FET 11, the coil 1, and the FET 12. At this time, VP is lower than the ground potential by the voltage across the resistor 11b, and VN is higher than the ground potential by the voltage across the resistor 12b. In a state where the electromagnetic coil operating device is preferable, since the currents flowing through the resistors 11b and 12b are the same, the absolute values of the voltages across the resistors 11b and 12b are equal, and the sum of VP and VN is zero. It is. For example, when the connection line at the connection point b of the coil 1 is short-circuited with the power supply connection line 16 to cause a power fault, the current flowing through the resistor 12b increases, so that the voltage between both ends increases, and VP and VN Is greater than zero. When such a voltage value is obtained, it can be determined that a power fault has occurred.
[0020]
In the CPU 3, a process for calculating the duty ratio of the drive pulse input to the coil 1, a process for comparing the duty ratio of each drive pulse with a predetermined duty ratio required for the A / D converter 7, a predetermined A process of counting the number of drive pulses below the duty ratio , and a process of adjusting the duty ratio of each drive pulse on condition that the count has reached a predetermined MAX value are executed.
Hereinafter, the predetermined duty ratio is indicated by X%, and the process for adjusting the duty ratio of each drive pulse is referred to as X% process, and the short-circuit determination control of the present embodiment will be described with reference to a flowchart.
[0021]
FIG. 2 is a flowchart for instructing X% processing. The CPU 3 counts the number of drive pulses less than X% within a predetermined period or periodically. That is, the calculated duty ratio of the drive pulse is compared with X% in S105, and while the duty ratio of the drive pulse greater than or equal to X% is calculated, the duty determination counter is cleared (S106) and the X% flag is set. It is set (S107).
[0022]
When the duty ratio of the drive pulse less than X% is calculated in S105, the duty determination counter is incremented in S108. Then, the X% flag is reset (S109), and the correction value is also cleared. This routine is continued, and when the duty determination counter reaches a predetermined MAX value by the increment, the routine of X% processing is entered (S103, S104).
[0023]
As shown in FIG. 3, in the routine of X% processing, a difference is obtained by subtracting X% from the duty ratio of the original drive pulse required for PWM control, and this is stored in the RAM 5 as a correction value ( S201). Next, instead of the calculated duty ratio of the driving pulse, the duty ratio of the driving pulse of X% is set (S202). Thus, by forcibly setting the duty ratio of the drive pulse of X%, the coil 1 is driven with the X% duty via the drive means. After the duty determination counter is cleared (S203), the X% flag is set (S204), and the process returns to the routine of FIG.
[0024]
The correction value obtained in the routine of the X% process is used for the correction process of the duty ratio of the next drive pulse . That is, the correction value that is excessive in PWM control is read prior to the next pulse formation, and as shown in FIG. 2, the duty of the drive pulse of the pulse formed next to the X% duty is as shown in FIG. It is subtracted from the ratio (FIG. 2, S102). In addition, since the duty determination counter is cleared together with the X% processing (FIG. 3, S203), once the X% duty is paid out, the X% processing is not performed until the predetermined MAX value is reached again. However, when performing control such that the input pulse train continuously includes a large number of duties less than X%, X% processing is performed at regular intervals defined by the duty determination counter. In this way, the total value of the X% duty and the corrected duty ratio of the drive pulse does not change, and the original operation amount is ensured as a whole. In this embodiment, the duty ratio of the drive pulse immediately after the X% processing is corrected, but any pulse after the X% processing may be corrected.
[0025]
If the X% flag is set as shown in FIG. 4, a failure determination process is performed. That is, in the failure determination routine, the setting of the X% flag is confirmed (S301), the true value is sampled by the A / D converter 7 in a state where conversion processing is possible, and failure determination is performed. In this manner, the coil 1 is driven with the X% duty on the condition that the X% flag is confirmed, and the potential at both ends of the coil at this time is taken into the CPU 3 via the A / D converter 7, so that a reliable short circuit is achieved. Determination (S302) is possible.
[0026]
【The invention's effect】
As described above, the failure determination device of the electromagnetic coil operation device of the present invention, in the calculating means, the duty ratio of each of the driving pulses A / D conversion while calculating the duty ratio of the driving pulses of the pulse train compared to the input processing or the like required time equivalent to a predetermined duty ratio of the vessel, when included drive pulses less than a predetermined duty ratio in the pulse train, causes input pulses of a predetermined duty ratio to the electromagnetic coil, the Since the short-circuit failure is determined when a pulse having a predetermined duty ratio is input, an accurate short-circuit determination can be made when control is performed in which the duty ratio of the drive pulse is lower than the predetermined duty ratio .
[0027]
Further, the calculation means counts the number of pulses less than the predetermined duty ratio , and when the number of pulses reaches a predetermined value, the duty ratio of each drive pulse after including the pulse of the predetermined duty ratio is calculated . According to the configuration in which a predetermined duty ratio can be set for any pulse in the pulse train by adjusting the duty ratio of each drive pulse so as not to change the total value, an accurate short circuit determination is possible. Since the original operation amount is returned, the controllability is not sacrificed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a short circuit determination device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing the control of this embodiment.
FIG. 3 is a flowchart of a process for adjusting a drive duty.
FIG. 4 is a flowchart for determining a short-circuit fault.
FIG. 5 is a configuration diagram of a conventional failure determination device for an electromagnetic coil actuator.
FIG. 6 is a configuration diagram of a failure determination device for an electromagnetic coil actuator that is PWM controlled.
FIG. 7 is a chart showing a pulse train driven by PWM control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electromagnetic coil 3 Calculation means 6, 9, 10, 11, 12 Drive means 9, 10, 11, 12 Switch means 16 Power supply line

Claims (3)

An H-bridge circuit in which both ends of the electromagnetic coil are connected to a power supply line and a ground line via a switch means, and a drive for selectively driving the switch means and PWM-controlling a drive pulse input to the electromagnetic coil And a duty ratio of the drive pulse , and a potential between both ends of the electromagnetic coil and the power supply potential of the power supply line captured from the A / D converter in synchronization with an arbitrary pulse among the drive pulses . comparison result, a failure judgment apparatus of an electromagnetic coil driving apparatus for chromatic and a calculating means for determining a short-circuit failure based on the selected state of the switch means driven by pulses the synchronizing,
The arithmetic means compares the duty ratio of the PWM-controlled drive pulse with a predetermined duty ratio having an on-time as the time required for the A / D conversion input process of the A / D converter , when containing the drive pulse duty ratio less than the predetermined duty ratio to the drive pulse, causes input drive pulses of the predetermined duty ratio to the electromagnetic coil by the drive means, when the driving pulse input of the predetermined duty ratio Contact And determining the short-circuit failure. A failure determination device for an electromagnetic coil operating device. An H-bridge circuit in which both ends of the electromagnetic coil are connected to a power supply line and a ground line via a switch means, and a drive for selectively driving the switch means and PWM-controlling a drive pulse input to the electromagnetic coil And a duty ratio of the drive pulse , and a potential between both ends of the electromagnetic coil and the power supply potential of the power supply line captured from the A / D converter in synchronization with an arbitrary pulse among the drive pulses . comparison result, a failure judgment apparatus of an electromagnetic coil driving apparatus for chromatic and a calculating means for determining a short-circuit failure based on the selected state of the switch means driven by pulses the synchronizing,
The arithmetic means compares the duty ratio of the PWM-controlled drive pulse with a predetermined duty ratio having an on-time as the time required for the A / D conversion input process of the A / D converter , by counting the number of pulses less than a predetermined duty ratio, when the pulse number reaches a predetermined value, each so as not to change the total value of the duty ratio of the driving pulse after including a pulse of the predetermined duty ratio A failure determination device for an electromagnetic coil operating device, wherein the predetermined duty ratio can be set to an arbitrary pulse in the drive pulse by adjusting the duty ratio of the drive pulse , and the short-circuit failure is determined . The arithmetic means inputs a pulse having the predetermined duty ratio instead of an arbitrary pulse, and calculates a correction value obtained by subtracting the predetermined duty ratio from the arbitrary pulse, and then a duty of a drive pulse input thereafter. The failure determination device for an electromagnetic coil operating device according to claim 2, wherein correction processing to be added to the ratio is performed.

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