JP5553432B2 - Load control circuit - Google Patents

Description

  The present invention relates to a load control circuit that controls a load provided outside, and is particularly suitable for use in accurately determining whether or not output information of an AD conversion circuit is appropriate.

  2. Description of the Related Art Conventionally, a load control circuit is widely known as a device that appropriately drives various loads. The load control circuit is equipped with a microcomputer or the like that performs signal processing, and generates and outputs an output signal in accordance with a predetermined input signal, thereby realizing control of a load provided outside.

  In order to process an analog input signal by a microcomputer, such a load control circuit is provided with an AD conversion circuit, converts the input signal from an analog value to digital information, and performs predetermined arithmetic processing based on the digital information. I am letting. At this time, if the digital information converted by the AD conversion circuit is an incorrect value, the processing result of the microcomputer also becomes an inappropriate value. Therefore, the load control circuit monitors the reference voltage of the AD conversion circuit and Many studies have been made to make digital information generated by a conversion circuit an appropriate value.

For example, Japanese Unexamined Patent Application Publication No. 2007-153272 (Patent Document 1) introduces a technique for correcting a reference voltage of an AD converter circuit mounted on an electronic control device for a vehicle to an appropriate value. A power supply voltage correction system composed of such an electronic control device (hereinafter referred to as ECU) is composed of a plurality of ECUs, one of which is referred to as a “reference ECU”. The excluded unit is referred to as “another ECU”. In the reference ECU, a vehicle battery is connected, receives drive power of the reference ECU from the vehicle battery, and applies the reference potential of the AD conversion circuit by the battery. Further, the AD conversion circuit uses a circuit with high resolution, detects the battery voltage of the vehicle battery by the AD conversion circuit, and stores the detected value of the stable battery voltage with a small amount of fluctuation in the memory circuit, The battery voltage of the vehicle battery is detected in real time, and the reference battery voltage detected thereby is transmitted to the central processing circuit mounted in the standard ECU at every AD timing. Then, the central processing unit CPU performs a comparison process between the battery voltage in the stable state and the reference battery voltage input at every AD timing, calculates a correction value by the comparison process, and based on this, from the AD conversion circuit It is possible to correct the output digital information to an appropriate value. The correction value is shared information of other ECUs connected via the communication line, and the other ECU corrects the output information of each AD conversion circuit to an appropriate value based on the correction value received as described above. Let

JP 2007-153272 A

  However, in the technique described in Patent Document 1, since the battery voltage that gives the reference potential to the AD converter circuit and the reference battery voltage that is supplied to the AD converter circuit for detection are supplied from the same battery unit, When the output voltage fluctuates, both the reference voltage of the AD conversion circuit and the reference voltage input to the AD conversion circuit are affected by the voltage fluctuation. Accordingly, the digital information output from the AD conversion circuit cannot be information reflecting the fluctuation state of the reference battery voltage because the reference voltage of the AD conversion circuit fluctuates. In the control device ECU, there is a problem that it is difficult to accurately recognize the fluctuation state of the battery voltage.

  In particular, in the electronic control unit ECU mounted on the vehicle, when the engine is started, the output value of the in-vehicle battery is drastically decreased to drive the start cell, or the output value undergoes high-frequency fluctuations. There arises a problem that the reference voltage of the AD conversion circuit becomes unstable and it is difficult to accurately recognize the fluctuation state of the battery voltage. Further, since the unstable state of the reference voltage is continued until the engine is stably driven, it is difficult to accurately recognize the fluctuation state of the battery voltage.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a load control circuit that can detect the fluctuation state of the battery voltage with high accuracy when the battery voltage supplied from the battery fluctuates.

In order to solve the above problems, the present invention has the following load control circuit configuration. That is, an AD conversion circuit that converts an input analog signal into digital information, a driving signal that drives a load based on an input signal input from the outside, and a sensing input from a sensor provided outside In a load control circuit comprising an information processing circuit that stops or permits the output of the drive signal based on a signal,
A main power source used as a drive power source for the information processing circuit and used as a reference potential for the AD converter circuit, and a sub power source which is a power source electrically independent from the main power source and gives a sub potential to the AD converter circuit It is supposed to have.

  Preferably, the AD conversion circuit outputs digitized power supply information by detecting the sub power supply, and the information processing circuit stops or permits output of the drive signal based on the power supply information. And

  More preferably, the load control circuit according to any one of the above-described inventions is used as a circuit unit of an electronic control device mounted on an automobile.

  According to the load control circuit of the present invention, the main battery that supplies the reference voltage of the AD converter circuit and the sub-battery that supplies the reference battery voltage (reference battery signal in the embodiment) are independent of each other. Therefore, the output voltage of one battery is not affected by the fluctuation of the output voltage of the other battery voltage. When the output voltage of the sub-battery is stabilized at a constant value, since the fluctuation state of the reference voltage of the AD converter circuit is monitored, the load control circuit determines whether the digital information generated by the AD converter circuit is appropriate. The determination is performed with high accuracy, and the fault diagnosis process of the load control circuit is realized with high quality.

  Further, when the load control circuit is applied to an electronic control unit ECU for a vehicle, if the battery voltage of the in-vehicle battery becomes unstable at the time of engine start or the like, the electronic control unit ECU accurately indicates the fluctuation state of the battery voltage. As a result, it is possible to realize fail-safe by failure diagnosis processing without performing control with malfunction.

The figure which shows the structure of the load control circuit which concerns on embodiment FIG. 3 is a diagram illustrating a configuration of an AD conversion circuit according to an embodiment Flowchart when performing AD conversion according to the embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a load control circuit according to the present embodiment. The load control circuit 01 includes a signal generation circuit 10, a main power supply 20, a power supply IC 30, a signal processing circuit 40, a load 50, a sensor 60, a power supply IC 70, and a sub power supply 80.

  The signal generation circuit 10 is provided outside the signal processing circuit 40 and outputs an input signal S1 having a pulse wave shape or a rectangular wave shape. The input signal S1 is received by the signal processing circuit 40 and converted into a predetermined output signal. The input signal S1 may be a signal generated by an operator's action, and is automatically transmitted from a peripheral circuit like a signal received by an electronic control unit (ECU) of an automobile. It may be.

  The main power supply 20 outputs a battery voltage of around 12V, and is connected to the signal processing circuit 40 via the power supply IC 30. The power supply IC 30 converts the battery voltage from 12V to 5V and is connected to an appropriate terminal provided in the signal processing circuit 40. The output voltage of the main power supply 20 is applied to the main power supply terminal Vcc and the AD terminal AVcc provided in the signal processing circuit 40 via the power supply IC 30. Here, the power applied to the main power supply terminal Vcc is used as power for driving the information processing circuit 41, and the potential applied to the AD terminal AVcc is used as a reference voltage for the AD conversion circuit 42. Therefore, the power supplied from the main power supply 20 is used as a drive power supply for the information processing circuit 41 and also used as a reference potential for the AD conversion circuit 42.

  The signal processing circuit 40 includes an information processing circuit 41 and an AD conversion circuit 42, and includes a signal input terminal Vdr, a main power supply terminal Vcc, an AD terminal AVcc, a signal output terminal Vout, a sensor terminal Vs, and a sub-battery detection. Terminal Vb is provided. Here, the signal input terminal Vdr, the sensor terminal Vs, and the sub-battery detection terminal Vb are connected to the AD conversion circuit 42 via a signal line or the like. Further, as described above, the main power supply terminal Vcc supplies the applied power to the information processing circuit 41, and the AD terminal AVcc supplies the applied potential to the AD conversion circuit 42 to provide a reference potential. The signal processing circuit 40 may be a one-chip LSI or a microcomputer incorporating a plurality of functional circuits, and does not ask for such a configuration.

  As illustrated, the information processing circuit 41 includes a central processing circuit 41a, a memory circuit 41b, and a clock circuit 41c. The information processing circuit 41 is connected to a bus line connected to the AD conversion circuit 42, and receives digital information generated by the AD conversion circuit 42 at every AD timing. Then, the information processing circuit 41 activates the control program stored in the memory circuit 41b and calculates an appropriate processing result according to the processing procedure defined by the control program. In addition, the information control circuit 41 performs a process of outputting an appropriate signal from a predetermined terminal based on the processing result calculated as described above, or stops the output of the signal according to a predetermined condition.

  The AD conversion circuit 42 is a circuit that converts an input analog signal into digital information. As shown in FIG. 2, the AD conversion circuit 42 according to the present embodiment includes an AD conversion circuit unit 42a, an AD conversion circuit unit 42b, and an AD conversion circuit unit 42c. Among these, the AD conversion circuit unit 42a is connected to the signal input terminal Vdr via the signal line, and is configured to receive the input signal S1 transmitted from the signal generation circuit 10. The AD conversion circuit unit 42b is connected to the sensor terminal Vs via a signal line, and receives the signal S3 generated by the sensor 60. Furthermore, the battery voltage (sub potential in the claims) of the sub power source 80 is applied to the AD conversion circuit unit 42c via the signal line. As shown in the figure, the AD conversion circuit 42 is connected to an AD terminal AVcc via a power supply line. Therefore, the battery voltage of the main power supply is supplied to the AD conversion circuit units 42a to 42c via the AD terminal AVcc, whereby each unit receives the reference voltage. The input signal S1 applied to the signal input terminal Vdr, the sensing signal S3 applied to the sensor terminal Vs, and the reference battery signal S4 are analog signals due to the nature of the sensing device and the like.

  The AD conversion circuit 42 having such a configuration realizes the following operation. The AD conversion circuit unit 42a detects the input signal S1 based on the reference voltage, samples the input signal S1 at every AD timing, and thereby generates digitized input signal information I1. Further, the AD conversion unit 42a outputs the input signal information I1 in response to a command received from the central processing circuit 42a. Further, the AD conversion circuit unit 42b detects the sensing signal S3 based on the reference voltage, samples the sensing signal S3 at each AD timing, generates digitized sensing information I3, and according to a predetermined timing, The sensing information I3 is output. Similarly, the AD conversion circuit unit 42c detects the reference battery signal S4 based on the reference voltage, samples the reference battery signal S4 at every AD timing, and thereby digitized reference battery information I4 ( The power supply information in the claims is generated, and the reference battery information I4 is output according to a predetermined timing.

  Referring to FIG. 1 again, the load 50 is connected to the signal output terminal Vout via the signal line, and is driven according to the signal received from the signal processing circuit 40. The load 50 may be a control motor, a lighting device, a control device such as an inverter circuit, or may be an actuator or the like, and any device can be applied. Is possible.

  The sensor 60 is a device provided in the load 50. For example, when the load 50 is a control motor, the sensor 60 may be a detection device that detects the number of rotations of the control motor, or a thermistor that detects the ambient temperature. It may also be a device that detects the potential applied to both terminals of the control motor. That is, the sensor 60 is a device that converts some information on the operation of the load 50 into an electrical signal and outputs the electrical signal.

  The sub power supply 80 outputs a battery voltage of about 12 V, and is connected to the signal processing circuit 40 via the power supply IC 70. The power supply IC 70 converts the battery voltage from 12V to 5V, and is connected to an appropriate terminal provided in the signal processing circuit 40. The sub power supply 80 is configured to be electrically independent from the main power supply 20, and provides a stable output voltage without being affected by the sudden drop in the output voltage of the main power supply 20. is there. Needless to say, a voltage dividing resistor may be provided between the signal processing circuit 40 and the power supply IC 30 or 70 to appropriately adjust the voltage value applied to the terminal of the signal processing circuit 40.

  The load control circuit 01 having such a configuration operates as follows. First, when supply of power from the main power supply 20 is started, the information processing circuit 41 is activated and a reference potential is applied to the AD conversion circuit 42. Here, when the input signal S1 (the input signal input from the outside in the claims) is transmitted from the signal generation circuit 10, the AD conversion circuit 42 digitizes the input signal S1. The data is converted into I1 and output to the information processing circuit 41. On the other hand, the sensing signal S3 is output from the sensor 60, and the AD conversion circuit 42 converts the sensing signal into sensing information I3 and outputs it to the information processing circuit 41 as before. At this time, the information processing circuit 41 appropriately drives the load 50 connected to the signal processing circuit 40 by generating a drive signal based on the input signal information I1 and outputting the drive signal.

  Further, in the information processing circuit 41, output control of the load drive signal S2 for driving the load 50 is performed based on the sensing information SI. More specifically, in the information processing circuit 41, an AND circuit that receives information indicating completion of drive signal output preparation and sensing information I3 as input is constructed by the control program, and the sensing information I3 indicates a value indicating an abnormal state. When this is done, the output of the drive signal S2 is stopped, and when the sensing information I3 indicates a normal state, the output of the drive signal S2 is permitted.

  Further, the AD conversion circuit 42 detects the reference battery signal S4 and generates reference battery information I4 based on the signal. Then, the reference battery information I4 is output to the information processing circuit 41 in accordance with a command from the central processing circuit 41a.

  Preferably, when the reference battery information I4 is abnormal, the output of the drive signal S2 is stopped, and when the reference battery information I4 is normal, the output of the drive signal S2 is permitted. As a result, the load control circuit 01 realizes fail-safe by failure diagnosis processing without performing control with malfunction. Hereinafter, such processing will be described with reference to FIG.

  FIG. 3A shows a fluctuation range of the reference voltage in the AD conversion circuit. Vmax is a maximum value that can increase the reference voltage, and the power supply IC 20 is designed not to output a voltage higher than Vmax. On the other hand, Vmin is the minimum value of the reference voltage, and the power supply IC 20 is designed so that a voltage lower than Vmin is not output. That is, the voltage value of the reference voltage always changes between Vmin and Vmax. In the same figure, an upper threshold value Vu indicating the normal range of the reference voltage and a lower threshold value Vd indicating the normal range of the reference voltage are shown. That is, the reference voltage Eth is in a normal state when Vd <Eth <Vu is satisfied, and is in an abnormal state when either Eth> Vu or Eth <Vd is satisfied.

  FIG. 3B shows a reference voltage determination process performed by the information processing circuit 41. When the reference voltage determination process is activated, the reference battery information I4 received from the AD conversion circuit unit 42c is detected, and it is determined whether or not the reference voltage Eth satisfies Vd <Eth <Vu (S001). More specifically, the reference battery information I4 takes into account that the voltage value Vth of the reference battery signal S4 is stable because the reference voltage Eth is compared with the potential of the reference battery signal S4. As shown, an offset value ΔI4 (ΔI4a to ΔI4d, etc.) from the voltage value Vth of the reference battery signal S4 is indicated. When the offset value ΔI4 indicates a value within a normal range, for example, ΔI4a or ΔI4c, the reference voltage Eth is in a normal state satisfying Vd <Eth <Vu, and therefore, as shown in FIG. As described above, without setting the abnormality flag (S002), the fail-safe process S004 recognizes the normal state and continues the output process of the drive signal S2. On the other hand, when the offset value ΔI4 deviates from the normal range, for example, ΔI4b or ΔI4d, the reference voltage Eth is in an abnormal state where either Eth> Vu or Eth <Vd. ), An abnormality flag is set (S003), and in the fail-safe process S004, the abnormality flag is detected, and the output process of the drive signal S2 is stopped.

  As described above, in the load control circuit 01 according to the present embodiment, the main power supply 10 that supplies the reference voltage of the AD converter circuit and the sub power supply 80 that supplies the reference battery signal S4 are independent of each other. The output voltage of one battery is not affected by the fluctuation of the output voltage of the other battery voltage. When the output voltage of the sub power supply 80 is stabilized at a constant value, the fluctuation state of the reference voltage of the AD conversion circuit 42 is monitored. Therefore, in the load control circuit 01, it is generated by the AD conversion circuit 42. The suitability determination of the digital information is performed with high accuracy, and the fault diagnosis process of the load control circuit 01 is realized with high quality.

  Further, when the load control circuit is applied to an electronic control unit ECU for a vehicle, if the battery voltage of the in-vehicle battery becomes unstable at the time of engine start or the like, the electronic control unit ECU accurately indicates the fluctuation state of the battery voltage. As a result, it is possible to realize fail-safe by failure diagnosis processing without performing control with malfunction.

01 Load Control Circuit 20 Main Power Supply 40 Signal Processing Circuit 41 Information Processing Circuit 42 AD Converter Circuit 50 External Load 60 Sensor 80 Sub Power Supply S1 Input Signal S2 Drive Signal S3 Sensing Signal S4 Sub Potential I4 Power Supply Information

Claims (3)

An AD conversion circuit that converts an input analog signal into digital information, a drive signal that drives a load based on the input signal input from the outside, and a sensing signal input from a sensor provided outside In a load control circuit comprising an information processing circuit for stopping or permitting the output of the drive signal based on
A main power source used as a drive power source for the information processing circuit and used as a reference potential for the AD converter circuit, and a sub power source which is a power source electrically independent from the main power source and gives a sub potential to the AD converter circuit load control circuit and having a, the. The AD converter circuit outputs the power supply information digitized by detecting the sub power supply,
The load control circuit according to claim 1, wherein the information processing circuit stops or permits the output of the drive signal based on the power supply information.   3. The load control circuit according to claim 1, wherein the load control circuit is used as a circuit unit of an electronic control device mounted on an automobile.

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