JP2018142811A - Load current control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to determine a state of a serial communication line connecting a controller and a current control circuit unit in a current control device.SOLUTION: A load current control device 10 includes: a current control circuit unit 12 connected with a load 20; and a controller 11 connected with the current control circuit unit via serial communication lines 13T and 13R. The controller 11 includes a determination unit 111 for determining states of the serial communication lines. The determination unit determines whether the serial communication lines are normal or abnormal on the basis of an indication current value indicated to the current control circuit unit via the serial communication lines, an output current value received from the current control circuit unit via the serial communication lines, and prescribed status information received from the current control circuit unit via the serial communication lines.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a load current control device.

  Current control devices that control the current of the load are widely used in many industrial fields, but the demand for downsizing of the current control devices has been increasing year by year. As a means to reduce the size of the current control device, use a current control IC (Integrated Circuit) that integrates a load current detection circuit, a current feedback function, an abnormality detection function of the conductor with the load, etc. into one package. It has been known. For example, Patent Document 1 discloses a technique related to a current control IC that controls a current flowing through a load.

  A current control IC described in Patent Document 1 controls a current flowing through a load based on a current detection unit that detects a current flowing through the load, and a detected current value and an instruction current value received from an external device through serial communication. And a function of converting the detected current value into serial communication data and transmitting it to an external device. Furthermore, the current control IC of Patent Document 1 includes a voltage detection unit that detects a voltage applied to the load. When it is detected that the voltage applied to the load is in an overvoltage state, a signal indicating the overvoltage state is serialized. It has a function to send it on the communication data.

JP 2009-284162 A

  However, the conventional technique described in Patent Document 1 has a problem that it is difficult to detect this abnormality when a ground fault or disconnection occurs in the serial communication line that connects the external device and the current control IC. Even when checking parity data, if a ground fault or disconnection abnormality occurs in the serial communication line, all of the parity bits and the bits that enable / disable the parity check are set to 0. Cannot be detected.

  The present invention has been made in view of the above problems, and its purpose is to determine the state of a serial communication line that connects the controller in the current control device and the current control circuit unit. The object is to provide a current control device.

  In order to solve the above problems, a current control device for a load according to the present invention includes a current control circuit unit connected to a load, and a current control for a load including a controller connected to the current control circuit unit via a serial communication line. The controller includes a determination unit that determines the state of the serial communication line. The determination unit serially instructs the current control circuit unit through the serial communication line and the current value that is indicated from the current control circuit unit. Whether the serial communication line is normal or abnormal is determined based on the output current value received via the communication line and predetermined status information received via the serial communication line from the current control circuit unit.

  According to the present invention, the controller in the current control device can determine the state of the serial communication line connected to the current control circuit unit in the current control device.

It is a whole block diagram of a current control apparatus. It is explanatory drawing which shows the structural example of the data communicated between a microcomputer and current control IC. It is a flowchart of a communication line state determination process.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The load current control device 10 according to the present embodiment includes a microcomputer 11 as a “controller” and a current control IC 12 as a “current control circuit unit”. The microcomputer 11, the current control IC 12, Are connected by serial communication lines 13T and 13R.
As will be described in detail later, the microcomputer 11 transmits transmission data 14 indicating a current value equal to or greater than a predetermined threshold value to the current control IC 12, and after a predetermined time has elapsed, Based on this, it is determined whether the serial communication lines 13T and 13R are normal or abnormal. The microcomputer 11 can store the determination result (only the result when it is determined to be abnormal) and can output an alarm to the outside.

  According to this embodiment configured as described above, it is possible to detect a ground fault or disconnection of the serial communication lines 13T and 13R from the microcomputer 11 to the current control IC 12, and to promptly notify the user of the abnormality. It becomes possible. Thereby, the reliability and usability of the current control device 10 can be improved.

  A first embodiment will be described with reference to FIGS. FIG. 1 shows a case where a load current control device 10 is applied to an automobile. Current control device 10 instructs a current value to be applied to load 20 in accordance with a control command from ECU (Engine Control Unit) 30. The load 20 is, for example, a linear solenoid or an electric motor. The load 20 can be configured as an actuator such as a hydraulic control valve. Note that the current control device 10 of the present embodiment can be widely applied to, for example, construction machines, industrial machines, robots, and the like other than automobiles.

  The current control device 10 is a device that controls a current to the load 20, and includes, for example, a microcomputer 11 and a current control IC 12. The microcomputer 11 and the current control IC 12 are connected via serial communication lines 13T and 13R, and exchange data via the serial communication lines 13T and 13R. In serial communication using the serial communication lines 13T and 13R, for example, an interface such as SPI (Serial Peripheral Interface) can be used. However, the type of communication interface is not particularly limited. The serial communication line 13T is used when sending transmission data 14 from the microcomputer 11 to the current control IC 12. The serial communication line 13R is used when the microcomputer 11 receives the reception data 15 from the current control IC 12. When the transmission and reception are not distinguished, the serial communication lines 13T and 13R are called serial communication lines 13.

  The microcomputer 11 includes, for example, a microprocessor, a memory, and a communication circuit (all not shown), and a predetermined computer program (not shown) is stored in the memory. When the microprocessor reads and executes a predetermined computer program, the function of the communication line state determination unit 111 is realized. The communication line state determination unit 111 is a function for determining whether or not the serial communication line 13 is in a state, and includes an alarm unit 1111 and an abnormality determination result storage unit 1112. The processing content of the communication line state determination unit 111 will be described later with reference to FIG.

  The current control IC 12 includes, for example, a PWM (Pulse Width Modulation) pulse output function, an output current value detection function, an overvoltage state detection function, a parity check function, and a parity check invalidation function.

  The PWM pulse output function is a function for outputting a PWM pulse as the control signal 22 to the load 20 based on the instruction current value in the transmission data 14 received from the microcomputer 11. The output current value detection function is a function for detecting the output current value 23 of the load 20. The overvoltage state detection function is a function for detecting that the voltage applied to the load 20 is in an overvoltage state. The parity check function is a function for detecting a data error using a parity bit included in the data 14 received from the microcomputer 11. The parity check invalidation function is a function for invalidating the parity check when a predetermined bit in the data 14 received from the microcomputer 11 is set to zero.

  The current control IC 12 uses the above-described functions to control the current flowing to the load 20 according to the current value indicated by the microcomputer 11 and to detect the current value and the overvoltage state that actually flowed to the load 20. To the computer 11.

  Furthermore, the current control IC 12 includes a disconnection detection unit 121 that determines whether a ground fault or disconnection has occurred in the signal lines 21T and 21R connected to the load 20. The signal line 21T is a line through which a signal flows from the current control IC 12 to the load 20, and the signal line 21R is a return line. When the two are not distinguished, they are called signal lines 12. It can also be referred to as a conducting wire 12 instead of the signal line.

  A current flows into the load 20 by a PWM pulse signal output from the current control IC 12. Thereby, for example, an electromagnetic valve or the like is opened and closed to control the hydraulic pressure.

  The ECU 30 is a computer system that controls the automobile. The ECU 30 determines the number of revolutions of the electric motor, the fuel injection amount, the intake air amount, the transmission operation, and the like based on signals from sensors (not shown), steering, brake pedals, accelerator pedals, etc., and implements them. The control command is output to each part. The current control device 10 is one of a group of devices that receive a control command from the ECU 30.

  FIG. 2 shows a configuration example of data 14 and 15 flowing between the microcomputer 11 and the current control IC 12. An example of data 14 transmitted from the microcomputer 11 to the current control IC 12 is shown on the upper side of FIG. 2, and an example of data 15 transmitted from the current control IC 12 to the microcomputer 11 is shown on the lower side of FIG. It is shown. The data 14 and 15 are configured as 1-byte or 2-byte data, respectively.

  2 includes, for example, a parity bit 141, a parity function enable / disable setting bit 142, and an instruction current value 143.

  There are two types of data abnormality detection functions by parity check, odd parity and even parity. For example, when performing data processing for adding consecutive data, even parity is often used because error checking is easier with even parity.

  When the current control IC 12 is used in an environment with strong noise resistance, it is possible to reduce an electrical load on an internal circuit of the current control IC 12 by omitting an unnecessary parity check. Therefore, the parity check can be disabled by setting the parity check enable / disable setting bit 142 to zero.

  The data 15 shown in the lower side of FIG. 2 includes, for example, a ground fault detection bit (ground fault state) 151 for detecting a ground fault of the signal line 21 connected to the load 20, and a current value (output current value) actually flowing to the load 20 ) 152, an overvoltage state signal 153, a communication parity error detection bit 154, and a parity bit 155.

  In the current control IC 12, when the serial communication line 13T from the microcomputer 11 to the current control IC 12 is grounded or disconnected, the data 14 shown on the upper side of FIG. That is, the parity bit 141, the instruction current value 143, and the parity function enable / disable setting bit 142 of the data 14 are all zero.

  When an abnormality occurs in the serial communication line 13T, in the data 15 sent from the current control IC 12 to the microcomputer 11, the value of the actual current value 152 (the output current value 23 in FIG. 1) becomes zero. Since zero is set for the command current value 143 in the data 14, the current control IC 12 controls energization to the load 20 in accordance with the command current value 143. Since neither an overvoltage nor a communication parity error occurs, both the overvoltage state 153 and the communication parity error detection bit 154 become zero. Furthermore, since no ground fault has occurred in the lead wire with the load, the bit 151 for detecting the ground fault of the signal line 21 with the load 20 is also zero.

  FIG. 3 is a flowchart for explaining a communication line state determination process performed by the microcomputer 11.

  This process may be executed, for example, at a predetermined cycle that is set in advance, or may be executed every time a predetermined trigger is reached. For example, when acceleration equal to or greater than a predetermined value is applied to the current control device 10, the process of FIG. 3 is performed based on a change in the surrounding environment of the current control device 10, such as when there is a temperature change greater than or equal to a predetermined value. May be.

  The microcomputer 11 transmits an instruction current value other than zero to the current control IC 12 (S10). In the flowchart, symbol i is given to the indicated current value. The command current value is set to the command current value 143 of the transmission data 14 and transmitted to the current control IC 12.

  The microcomputer 11 determines whether an abnormality has occurred in the serial communication line 13T (transmission line) from the microcomputer 11 to the current control IC 12 when a predetermined time has elapsed after transmitting the instruction current value to the current control IC 12. (S11).

  In step S11 for determining the presence or absence of abnormality, occurrence of abnormality is detected based on a plurality of conditions. As an example, a case will be described here in which it is determined that an abnormality has occurred in the serial communication line 13T when all four conditions are satisfied.

  The first condition is that “indicated current value i ≧ predetermined threshold value Thi”. The second condition is that “actual current value = 0”. In spite of the first condition and the second condition instructing the current control IC 12 to pass a current not less than a predetermined threshold value Thi other than zero, the correct serial communication data 14 is actually This is to determine that the current control IC 12 has not been transmitted.

  However, the state of “indicated current value i ≧ predetermined threshold Thi” and “actual current value = 0” is the ground of the transmission line 13T from the microcomputer 11 to the current control IC 12 for the purpose of detection in the present invention. It is not a condition specific to an event of tangling or disconnection.

  This state occurs even in the event that a ground fault occurs in the signal line 21 between the current control IC 12 and the load 20, or only one bit of data is garbled in the data 14 transmitted from the microcomputer 11 to the current control IC 12. May occur even if the current control IC 12 does not accept the command current value due to the parity error.

  Therefore, in the present embodiment, the third condition and the fourth condition are defined in order to distinguish these events from the ground fault or disconnection event that occurred in the transmission line 13T from the microcomputer 11 to the current control IC 12. It adds to step S11.

  The third condition is that “a ground fault detection bit generated in the signal line 21 with the load 20 = 0”, that is, no ground fault is detected in the signal line 21. The fourth condition is that “communication parity error detection bit = 0”, that is, no parity error is detected in the communication between the microcomputer 11 and the current control IC 12.

  If even one of the four conditions described above is not satisfied, NO is determined in step S11 and the process proceeds to step S12. The microcomputer 11 determines that the transmission line 13T from the microcomputer 11 to the current control IC 12 is normal, and ends this process.

  On the other hand, when all the above four conditions are satisfied, YES is determined in step S11, and the process proceeds to step S13. The microcomputer 11 determines that a ground fault or disconnection has occurred in the transmission line 13T from the microcomputer 11 to the current control IC 12, and stores this determination result in the abnormality determination result storage unit 1112. The abnormality determination result storage unit 1112 is preferably a non-volatile memory or a volatile memory backed up by a battery or the like.

  The microcomputer 11 activates the alarm unit 1111 based on the determination result stored in step S13 (S14). For example, the alarm unit 1111 performs alarm processing such as turning on a warning light, sounding an alarm buzzer, or displaying a warning message on a display or the like, and ends this processing.

  According to this embodiment configured as described above, since it is possible to determine whether or not an abnormality has occurred in the serial communication line 13T that sends data 14 from the microcomputer 11 to the current control IC 12, the reliability of the current control device 10 can be determined. Improves sex and usability.

  In the case of the prior art, when the serial communication line 13T is grounded or disconnected, all the bits of the data 14 received by the current control IC 12 become zero, so the instruction current value 143, the parity bit 141, the parity check enable / disable setting bit 142 becomes all zeros. Since the parity check valid / invalid setting bit 142 is zero, the abnormality detection function by the parity check does not work. For this reason, the current control IC 12 receives the data 14 as normal data and performs current control so that the current of the load 20 becomes zero. As described above, in the related art, even if an instruction current value that is not originally zero is transmitted to the current control IC 12, it is not possible to detect an abnormality in the serial communication line. On the other hand, according to the present embodiment, an abnormality of the serial communication line 13T (transmission line 13T) can be detected by transmitting an instruction current value other than zero to the current control IC 12.

  In addition, this invention is not limited to embodiment mentioned above. A person skilled in the art can make various additions and changes within the scope of the present invention. In the above-described embodiment, the present invention is not limited to the configuration example illustrated in the accompanying drawings. The configuration and processing method of the embodiment can be changed as appropriate within the scope of achieving the object of the present invention.

  Moreover, each component of the present invention can be arbitrarily selected, and an invention having a selected configuration is also included in the present invention. Further, the configurations described in the claims can be combined with combinations other than those specified in the claims.

  10: current control device, 11: microcomputer, 12: current control IC, 13T: serial communication line (transmission), 13R: serial communication line (reception), 21: signal line, 20: load, 30: ECU

Claims (4)

A load current control device comprising: a current control circuit unit connected to a load; and a controller connected to the current control circuit unit via a serial communication line,
The controller has a determination unit that determines the state of the serial communication line,
The determination unit includes an instruction current value instructed to the current control circuit unit via the serial communication line, an output current value received from the current control circuit unit via the serial communication line, and the current control circuit unit Determining whether the serial communication line is normal or abnormal based on predetermined status information received via the serial communication line from
Load current control device. The predetermined status information includes a ground fault detection information indicating whether a ground fault has occurred in a signal line between the current control circuit unit and the load, and a parity for serial communication between the controller and the current control circuit unit. And parity error detection information indicating whether an error has occurred,
The load current control device according to claim 1. The determination unit
(1) The indicated current value instructed to the current control circuit unit via the serial communication line is equal to or greater than a predetermined threshold value.
(2) the output current value received from the current control circuit unit via the serial communication line indicates 0;
(3) the ground fault detection information indicates a normal state;
(4) the parity error detection information indicates a normal state;
When all the conditions are satisfied, it is determined that an abnormality has occurred in the serial communication line.
The load current control device according to claim 2. The controller transmits the instruction current value via the serial communication line to the current control circuit unit according to an instruction from a host device.
The controller activates the determination unit when the instruction current value determined according to an instruction from the host device is equal to or greater than the predetermined threshold value.
The load current control device according to any one of claims 1 to 3.

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