JP2006020427A - System control method and control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the breakage of existing data in the case where power abnormality occurs under low voltage. <P>SOLUTION: A control system, which acquires control data on a motor 1 and stores these data in an EEPROM 9, is provided with a voltage detecting circuit 11, which detects the voltage of power supplied to the control system. When abnormality is detected in a battery 4 by the voltage detecting circuit 11, this control system closes a relay 3 for prevention of reverse connection and connects a capacitor C2 provided in a H bridge circuit 2 for ripple absorption with a regulator 8. At occurrence of abnormality in the power source, power is supplied to a CPU5 also from a capacitor C2 in addition to a capacitor 1. Hereby, this can elongate the data write time, using the existing capacitor C2, and the data write time at occurrence of power abnormality is secured, and the existing data are protected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control method for various control systems, and more particularly to a data protection technique in a system that drives and controls various devices while writing data acquired during operation to a storage element or the like.

  Conventionally, a system is known in which data acquired during operation is written into a storage element such as an EEPROM or a ROM area of a flash microcomputer, and the operation of a motor or the like is controlled based on the data. For example, in a wiper device for an automobile, a system for acquiring the wiper blade position, operation speed, operation frequency, etc., as needed, and controlling the operation of the wiper blade in real time has been developed. Yes.

  FIG. 5 is an explanatory diagram showing the configuration of such a wiper device control system. The wiper device is driven by a motor 51, and the wiper blade reciprocates on the windshield by forward and reverse rotation of the motor 51. As shown in FIG. 5, the motor 51 is connected to an H bridge circuit 52 using FETs 1 to 4. The H bridge circuit 52 is connected to the battery 54 via a relay 53 for preventing reverse connection. The relay 53 is controlled by a drive circuit 56 connected to the CPU 55.

  The FETs 1 to 4 of the H bridge circuit 52 are controlled by a drive circuit 57. The drive circuit 57 is also connected to the CPU 55, and under the instruction of the CPU 55, the FETs 1 to 4 are appropriately turned on / off to rotate the motor 51 forward and backward. The H bridge circuit 52 is further provided with a ripple absorbing capacitor C2. One end side of the capacitor C2 is connected to a connection point between the H bridge circuit 52 and the battery 54, and the other end side is grounded.

The CPU 55 is connected to a regulator 58, and power is supplied from the power source Vcc by the regulator 58. The regulator 58 is connected to the battery 54 via the diode D1. A capacitor C1 whose other end is grounded is connected between the regulator 58 and the diode D1. An EEPROM 59 is also connected to the CPU 55. The EEPROM 59 stores various control data (for example, wiper blade position, operation speed, number of operations, etc.) necessary for controlling the wiper device.
JP 2000-184780 A

  However, in the previous system, if a power failure occurs suddenly due to disconnection of the connector while the CPU 55 is writing data to the EEPROM 59, new data cannot be written or the previous data in the EEPROM 59 is destroyed. There is a fear. For this reason, in the control system as shown in FIG. 5, in the case of such a power supply abnormality, the data write time is secured by using the capacity of the backup capacitor C1, and the data is maintained.

On the other hand, the CPU 55 and the regulator 58 are reset due to a voltage drop or are in an output stop state. For this reason, it is necessary to finish data writing before the supply voltage falls below V ₀ which is a threshold value for resetting or the like. FIG. 5 is an explanatory diagram showing the relationship between the time change of the power supply voltage and the data writing time when the power supply is abnormal in the control system of FIG. As shown in FIG. 5, when the power supply voltage is 12 V, the voltage supplied to the CPU 55 changes as indicated by a solid line due to the discharge characteristics of the capacitor C1. In this case, a time TV (hereinafter, this time is abbreviated as a voltage drop time TV) from when the power supply abnormality occurs until the voltage becomes V ₀ or less is T ₁ , which is a time TD (hereinafter referred to as “data writing time”). This time exceeds the data writing time TD). Therefore, the data writing time TD is ensured after the occurrence of the abnormality, and the data is updated without destroying the previous data.

On the other hand, when the power supply voltage is lowered to 9V, the voltage supplied to the CPU 55 changes like a one-dot chain line. In this case, the voltage drop time TV is shorter than T ₂ next data write time TD. Therefore, the time for writing data is not secured, and not only the data cannot be updated, but also the previous data may be destroyed. In this case, if the capacitance of the capacitor C1 is increased, the voltage drop time TV can be extended correspondingly, and the power supply voltage can be reduced. However, this requires a large-capacity capacitor, which is limited in terms of cost, circuit space, and the like, and it is difficult to cope with a decrease in power supply voltage without limit.

  An object of the present invention is to prevent the destruction of existing data when a power supply abnormality occurs under a low voltage.

  The system control method of the present invention includes a control unit that acquires data relating to a control target and stores the data in a storage unit, a power source that supplies power to the control unit, and a power source that is applied from the power source to the control unit. A control method for a control system, comprising: voltage detection means for detecting a power supply voltage, a first capacitor connected between the power supply and the control means, and a second capacitor connected to the control target. And when abnormality is detected in the power supply by the voltage detection means, power is supplied to the control means by the first capacitor and the second capacitor.

  In the present invention, when power supply abnormality occurs, power is supplied not only to the first capacitor but also from the second capacitor connected to the controlled object, so that the capacity for backup increases, Data writing time increases. Further, the backup capacitor capacity increases without increasing the capacity of the first capacitor or increasing the number of capacitors.

  In the system control method, a switch unit is provided between the power source and the control target, and when an abnormality occurs in the power source, the switch unit is closed and power is supplied from the second capacitor to the control unit. You may do it. In this case, voltage detection means for detecting a power supply voltage applied from the power supply to the control system is provided, and the switch means is closed when a drop in the power supply voltage is detected by the voltage detection means. Also good.

  In the system control method, a motor may be the control target, and the second capacitor may be disposed for ripple absorption in the motor drive circuit. In the system control method, the switch unit may be a reverse connection prevention unit that cuts off an electrical connection between the power source and the motor drive circuit when they are connected in reverse polarity. .

  In the system control method, the motor may be incorporated in a vehicle as a vehicle electrical component. When the motor is used as a motor with a control circuit for a vehicle electrical component, there is no need to newly provide a backup capacitor, and the motor does not need to be enlarged, so that the vehicle can be stored in a limited space in the vehicle. Electrical components can be reduced in weight and size.

  The control system of the present invention includes a control unit that acquires data relating to a control target and stores the data in a storage unit, a power source that supplies power to the control unit, and a power source that is applied from the power source to the control system A voltage detecting means for detecting a voltage; a first capacitor connected to the power supply; capable of supplying power to the control means when an abnormality occurs in the power supply; and a second capacitor connected to the control object And a switch means connected to the control means and capable of supplying power to the control means from a second capacitor when an abnormality of the power source is detected by the voltage detection means.

  In the present invention, when an abnormality is detected in the power supply, the switch means is controlled by the control means, and power can be supplied from the second capacitor to the control means. That is, when a power supply abnormality occurs, power can be supplied to the control means not only from the first capacitor but also from the second capacitor connected to the controlled object. For this reason, the capacity for backup when a power supply abnormality occurs increases, and the data writing time increases. Further, the backup capacitor capacity increases without increasing the capacity of the first capacitor or increasing the number of capacitors.

  According to the system control method of the present invention, when an abnormality occurs in the power supply, power is supplied to the control means by the first capacitor connected to the power supply and the second capacitor connected to the control target. When the power supply abnormality occurs, the backup capacitor capacity increases, and the data writing time can be extended. Therefore, since the data writing time is secured when the power supply abnormality occurs, the previous data is prevented from being destroyed and the existing data can be protected. Further, the capacity for backup can be increased without increasing the capacity of the first capacitor or the number of capacitors, and the data reliability can be improved without increasing the cost and circuit space. Is possible.

  According to the control system of the present invention, when a power supply abnormality is detected, the switch means that enables power supply to the control means from the second capacitor connected to the controlled object is provided, so that an abnormality has occurred in the power supply. When power is supplied not only to the first capacitor but also from the second capacitor to the control means, the capacity of the backup capacitor when the power supply abnormality occurs increases and the data writing time can be extended. Therefore, since the data writing time is secured when the power supply abnormality occurs, the previous data is prevented from being destroyed and the existing data can be protected. In addition, the capacity for backup can be increased without increasing the capacity of the first capacitor or the number of capacitors, and the data reliability can be improved without increasing cost and circuit space. Is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram showing the configuration of a control system to which the data protection method according to the first embodiment of the present invention is applied. The control system of FIG. 1 uses a motor 1 as a control target, and is used for driving control of a wiper device, for example. The motor 1 is connected to a wiper blade via a link mechanism or the like (not shown), and the wiper blade performs a reciprocating wiping operation on the windshield by forward / reverse rotation of the motor 1.

  The motor 1 is connected to an H bridge circuit 2 using FETs 1 to 4. The H bridge circuit 2 is connected to a battery (power source) 4 via a relay 3 for preventing reverse connection. The relay 3 is controlled by a drive circuit 6 connected to a CPU (control means) 5 and is normally in an open state. When the battery 4 is correctly connected, the relay 3 is closed in accordance with the drive command of the motor 1, and the H bridge circuit 2 and the battery 4 are electrically connected.

  The FETs 1 to 4 of the H bridge circuit 2 are controlled by the drive circuit 7. The drive circuit 7 is also connected to the CPU 5, and under the command of the CPU 5, the FETs 1 to 4 are appropriately turned on / off to rotate the motor 1 forward and backward. The H bridge circuit 2 is further provided with a ripple absorbing capacitor C2. One end side of the capacitor C2 is connected to a connection point between the H bridge circuit 2 and the battery 4, and the other end side is grounded.

  The CPU 5 is connected to the regulator 8, and power is supplied from the power source Vcc by the regulator 8. The regulator 8 is connected to the battery 4 via the diode D1. A capacitor C1 having the other end grounded is connected between the regulator 8 and the diode D1. A voltage detection circuit 11 (voltage detection means) is arranged in parallel with the regulator 8 so that a voltage value applied from the battery 4 to the regulator 8 can be detected. An EEPROM (storage means) 9 is also connected to the CPU 5. The EEPROM 9 stores various data necessary for controlling the wiper device as needed.

  In such a control system, as described above, the charge stored in the capacitor C1 decreases as the power supply voltage value decreases. For this reason, the voltage drop time TV when the power supply abnormality occurs is shortened, and the data writing time cannot be secured, so that existing data may be destroyed. If the capacitance of the capacitor C1 is increased, the voltage drop time TV can be extended, but this is not easy due to problems such as cost and circuit space.

  On the other hand, looking back at the system of FIG. 1, a capacitor C2 is provided in the system separately from the backup capacitor C1. Capacitor C2 is provided to absorb ripples during motor operation, and when the power supply abnormality occurs and motor 1 stops, the charge stored in capacitor C2 is then spontaneously discharged. Therefore, if the charge of the capacitor C2 that is naturally discharged can be used for backup, the voltage drop time TV can be extended.

  Therefore, in the control system, when a power supply abnormality is detected, power is supplied to the CPU 5 from C2 in addition to C1, thereby extending the voltage drop time TV. FIG. 2 is an explanatory diagram showing the relationship between the time change of the power supply voltage and the data writing time when a power supply abnormality occurs in the control system of FIG. Here, the power supply voltage is constantly monitored by the voltage detection circuit 11, and when the CPU 5 detects a power supply abnormality due to a voltage drop, the CPU 5 maintains the closed state of the relay 3 using the drive circuit 6 which is a reverse connection protection circuit. Thereby, the capacitor C2 is short-circuited to the regulator 8 side when a power supply abnormality occurs.

When the power supply voltage decreases, the electric charges are discharged from the capacitors C1 and C2. As shown in FIG. 2, compared with the discharge characteristic in the case of only C1 indicated by the alternate long and short dash line, in the case of C1 + C2, the voltage decrease becomes gentle and the voltage decrease time TV becomes longer as indicated by the solid line. That is, as shown in FIG. 5, the C1-only backup, if the supply voltage is 9V whereas the voltage drop time TV shorter than T ₂ next data write time TD, the TV in the backup with C1 + C2 T _{3 and} becomes longer than the data writing time TD (T ₃ > TD). Therefore, a sufficient data writing time TD is ensured when a power failure occurs, a situation where the CPU 5 stops functioning during the data writing operation can be avoided, destruction of existing data is prevented, and data reliability is ensured. .

  In addition, in this control method, since the capacitor for absorbing ripple existing in the circuit is used for backup, the capacity for backup is actually increased without increasing the capacity of the capacitor C1 or increasing the number of capacitors. Can be increased above. Therefore, it is possible to earn a backup capacitor capacity without increasing cost and circuit space.

  Next, as a second embodiment of the present invention, a description will be given of a control mode in which backup using only C1 and backup using C1 + C2 are selectively used according to the detected power supply voltage value. As shown in FIG. 5, when the power supply voltage is 12 V, TV> TD is satisfied even with backup using only C1, and the data writing time can be secured. That is, if the power supply voltage value is high to some extent, the data writing time can be secured without performing backup by C2.

  Therefore, it is possible to determine whether or not the capacitor C2 is used based on the power supply voltage value detected by the voltage detection circuit 11, and to perform backup using C2 only when the data writing time is insufficient with only C1. For example, when there is a possibility that TV <TD when the power supply voltage is less than 10.5 V, 10.5 V is set as the threshold value VS, and whether or not C2 is used is determined. That is, when the power supply voltage value is 10.5 V (VS) or more, the relay 3 is in an open state and backup by C2 is not performed. On the other hand, when the power supply voltage value becomes less than 10.5 V (VS), the relay 3 is closed and the backup by C2 is used together.

  On the other hand, the data writing time TD varies depending on the amount of data. For example, in the case of a wiper device, speed data and position data are included when the wiper blade is operating, but only position data is included when the wiper blade is stopped, and there is a difference in the data amount between them, and writing time is also different. If the data amount is small, the data writing time becomes short. If the data amount is small, there is a possibility that the data writing time can be secured even when the power supply voltage is low. Therefore, the backup mode is changed according to the amount of data to be stored, and if a power supply abnormality occurs, the data writing time TD is predicted from the amount of data to be stored at that time, and C1 and C1 + C2 are set accordingly. You can use them properly.

FIG. 3 is a functional block diagram relating to the data writing process when the power supply abnormality of the CPU 5 occurs in the third embodiment. As shown in FIG. 3, the CPU 5 is first provided with a voltage reduction time calculation unit (voltage reduction time calculation means) 12 that is connected to the voltage detection circuit 11 and calculates the voltage reduction time TV from the current voltage. Based on the power supply voltage, the voltage drop time calculation unit 12 calculates a voltage drop time TV _K indicating a time from when the power supply abnormality occurs until the voltage becomes V ₀ or less. The CPU 5 is provided with a ROM 16 and stores a voltage drop time TV _K corresponding to the detected voltage value in a mapped manner. CPU5 is referring to the map based on the detected power supply voltage by the voltage detection circuit 11, calculates the voltage drop time TV _K.

The CPU 5 is also provided with a data write time calculation unit (data write time calculation means) 13 for calculating a data write predicted time TD _P indicating a time required for writing the current data to the EEPROM 9 when a power supply abnormality occurs. It has been. The ROM 16 also stores a mapping indicating the relationship between the data amount and the data writing prediction time TD _{P. The} data writing time calculation unit 13 performs various controls such as the position of the wiper blade, the operation speed, and the number of operations. The data writing prediction time TD _P is calculated by referring to the map according to the amount of data.

The calculated voltage drop time TV _K and the estimated data write time TD _P are compared by a comparison unit (comparison means) 14 provided in the CPU 5. At this time, if TV _K > TD _P , the data can be updated without destroying the previous data by backup using only C1. On the other hand, in the case of TV _K <TD _P , the data writing time is insufficient in the backup using only C1, and there is a possibility that the data cannot be updated and the previous data is destroyed. Therefore, the comparison unit 14 compares TV _K and TD _P , and when TV _K <TD _P , the relay 3 is closed and the backup by C2 is used together.

  As described above, in the control method according to the third embodiment, the data writing time is predicted according to the data amount, and the backup mode is determined based on the data writing time. It becomes.

Further, using a map showing the relationship between the voltage value and the voltage drop time TV _K described above, it may change the value of the threshold VS as described in Example 2. Here, first, the data writing time calculation unit 13 is used, and the data writing predicted time TD _P is obtained from the data amount. Next, referring to a map of the voltage drop time TV _K, a voltage value having a voltage drop time TV _K exceeding TD _P obtained by calculating from the map as the threshold VS _K. Then, the detected voltage value V _K is compared with the threshold value VS _K, and when V _K is equal to or higher than VS _K (V _K ≧ VS _K ), only C1 is used. Conversely, if V _K <VS _K , the relay 3 is closed and the backup by C2 is used together.

It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.
For example, in the above-described embodiment, the example in which the present invention is applied to the control system of the wiper apparatus has been described. However, the application target is not limited to the wiper apparatus, and data acquired during the system operation is written in the storage element or the like. Widely applicable to the system. The object to be controlled is not limited to a motor, and can be widely applied to control systems for other electric devices. Furthermore, in the above-described embodiment, the configuration in which the acquired data is written in the EEPROM 9 is shown. However, for example, the configuration may be such that the data is written in a storage element other than the EEPROM 9 such as a ROM area of a flash microcomputer.

  In the above-described embodiment, the control method of the present invention has been described by taking as an example a system in which only one capacitor is provided in addition to C1, but the present invention is applied to a system in which two or more capacitors are used in addition to C1. The invention can also be applied. In this case, a plurality of capacitors other than C1 serves as the second capacitor, and is used as a backup capacitor when a power supply abnormality occurs. Depending on the data amount, a plurality of second capacitors may be selected as appropriate and the number used may be adjusted.

  Further, in the above-described embodiment, the configuration in which the power supplied to the CPU 5 is ensured for the data write operation when the power supply abnormality occurs is shown. However, even if the operation other than the data write is performed using the power supply secured by the capacitor. good.

  In general, in an automobile wiper device, when the ignition switch is turned off, the CPU 5 is turned off after storing the data in the EEPROM 9 due to the OFF signal. The present invention is also effective for a system in which the power of the CPU 5 is directly turned off.

It is explanatory drawing which shows the structure of the control system to which the data protection method which is Example 1 of this invention is applied. It is explanatory drawing which shows the relationship between the time change of the power supply voltage at the time of power supply abnormality in the control system of FIG. 1, and data write time. FIG. 10 is a functional block diagram relating to data writing processing when a power supply abnormality occurs in a CPU in the control method according to the third embodiment. It is explanatory drawing which shows the structure of the conventional control system. FIG. 5 is an explanatory diagram showing a relationship between a time change of a power supply voltage and a data writing time when the power supply is abnormal in the control system of FIG. 4.

Explanation of symbols

1 Motor 2 H-bridge circuit 3 Relay 4 Battery (power supply)
5 CPU (control means)
6 Drive circuit 7 Drive circuit 8 Regulator 9 EEPROM (memory means)
11 Voltage detection circuit (voltage detection means)
12 Voltage drop time calculation unit (voltage drop time calculation means)
13 Data writing time calculation unit (data writing time calculation means)
14 Comparison part (comparison means)
15 Data writing unit (data writing means)
51 Motor 52 H Bridge Circuit 53 Relay 54 Battery 55 CPU
56 drive circuit 57 drive circuit 58 regulator 59 EEPROM
C1 capacitor (first capacitor)
C2 capacitor (second capacitor)
D1 diode TD data writing time TD _P data writing prediction time TV, TV _K voltage drop time V _K detected voltage value VS, VS _K threshold

Claims (7)

Control means for acquiring data related to a control target and storing the data in a storage means; a power supply for supplying power to the control means; and voltage detection for detecting a power supply voltage applied to the control means from the power supply A control system comprising: a means; a first capacitor connected between the power source and the control means; and a second capacitor connected to the control object,
A system control method comprising: supplying power to the control means by the first capacitor and the second capacitor when an abnormality is detected in the power source by the voltage detection means.   The system control method according to claim 1, wherein the control system includes a switch unit between the power source and the control target, and when the power source is abnormal, the switch unit is closed and the second capacitor is closed. A system control method, wherein power is supplied to the control means.   3. The system control method according to claim 2, wherein the control system includes voltage detection means for detecting a power supply voltage applied to the control system from the power supply, and the voltage detection means detects a decrease in the power supply voltage. When this is done, the switch means is closed.   4. The system control method according to claim 1, wherein the object to be controlled is a motor, and the second capacitor is disposed for ripple absorption in a drive circuit of the motor. 5. System control method.   6. The system control method according to claim 5, wherein the switch means is a reverse connection prevention means for cutting off an electrical connection between the power source and the motor drive circuit when they are connected in reverse polarity. A system control method characterized by the above.   6. The system control method according to claim 4, wherein the motor is incorporated in a vehicle as a vehicle electrical component. Control means for acquiring data relating to the controlled object and storing the data in the storage means;
A power supply for supplying power to the control means;
Voltage detection means for detecting a power supply voltage applied to the control system from the power supply;
A first capacitor connected to the power source and capable of supplying power to the control means when an abnormality occurs in the power source;
A second capacitor connected to the controlled object;
A control system connected to the control means, and having a switch means that enables power supply from the second capacitor to the control means when an abnormality of the power source is detected by the voltage detection means.

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