Electronic control device and electronic control method

Abstract

An electronic control device according to the present invention includes a reverse connection protection relay including a switching element and a rectifying element, the switching element and the rectifying element being connected in parallel, a negative electrode of the rectifying element and a positive electrode of the rectifying element are respectively connected to a negative electrode of a power source and a load, the load consumes power supplied from the power source, and the switching element is controlled to open and close on the basis of a switching control signal indicating whether or not power is supplied from the power source. The voltage detection part detects the potential difference between the two ends of the reverse connection protection relay, and the control device judges the state of the reverse connection protection relay according to the potential difference.

Description

Technical Field

[0001] The present disclosure relates to an electronic control device and an electronic control method. Background Art

[0002] Patent document 1 discloses an electronic control device, including: a reverse connection protection unit having a MOSFET as a switching element and a Zener diode as a reverse current prevention element; a power supply circuit generating a positive power supply voltage; a voltage detection unit detecting a voltage between the positive power supply voltage and a ground of a battery; an A / D conversion unit performing A / D conversion on a voltage output from the voltage detection unit; and a fault diagnosis unit performing fault diagnosis of the reverse connection protection unit based on an output value output from the A / D conversion unit. Patent document 1 discloses an electronic control device that uses a MOSFET as a reverse connection protection element between a load and a ground, and is capable of diagnosing a fault of the reverse connection protection element. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-42015 Summary of the invention Technical problem to be solved by the invention

[0004] In the electronic control device described in Patent Document 1, when a positive voltage is applied from the positive electrode of the battery to the gate of the MOSFET, conduction occurs between the drain and source of the MOSFET. Therefore, a short-circuit fault of the MOSFET cannot be detected by monitoring the positive power supply voltage alone. If the battery is reversely connected during a short-circuit fault, the current will flow in the reverse direction. The reverse flow of current becomes a cause of failure of the electronic control device. In order to avoid the reverse flow of current, redundancy of the reverse connection protection relay or the addition of a drive device for applying a positive power supply voltage to the gate of the MOSFET can also be considered. These methods require additional components or peripheral circuits, thereby increasing the circuit scale or cost.

[0005] An object of the present disclosure is to provide an electronic control device and an electronic control method that solve the above technical problems. Technical solutions to technical problems

[0006] According to a first method, an electronic control device includes a reverse connection protection relay, a voltage detection unit, and a control device, wherein the reverse connection protection relay includes a switching element and a rectifying element, wherein the switching element and the rectifying element are connected in parallel, wherein the negative pole of the rectifying element and the positive pole of the rectifying element are respectively connected to the negative pole of a power supply and a load, wherein the load consumes power provided by the power supply, wherein the opening and closing of the switching element is controlled based on a switching control signal indicating whether or not power is supplied from the power supply, wherein the voltage detection unit detects a potential difference across the reverse connection protection relay, and wherein the control device determines a state of the reverse connection protection relay based on the potential difference.

[0007] According to the second method, an electronic control method for an electronic control device is provided, the electronic control device comprising a reverse connection protection relay, a voltage detection unit and a control device, the reverse connection protection relay comprising a switching element and a rectifying element, the switching element and the rectifying element being connected in parallel, the negative pole of the rectifying element and the positive pole of the rectifying element, the negative pole of the rectifying element and the positive pole of the rectifying element being connected to the negative pole of a power supply and a load respectively, the load consuming power provided from the power supply, the opening and closing of the switching element being controlled based on a switching control signal indicating whether or not power is supplied from the power supply, the electronic control method executing: a first step in which the voltage detection unit detects a potential difference between both ends of the reverse connection protection relay; and a second step in which the control device determines a state of the reverse connection protection relay based on the potential difference. Effects of the Invention

[0008] According to the present disclosure, it is possible to economically detect a failure of a reverse connection protection relay. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a circuit diagram showing a configuration example of an electronic control device according to the first embodiment. Figure 2 1 is a circuit diagram showing an example of a circuit configuration around a reverse connection protection relay according to the first embodiment. Figure 3 It is an explanatory diagram for explaining a specific example of the method for determining the state of the reverse connection protection relay according to the first embodiment. Figure 4 It is a circuit diagram showing a configuration example of an electronic control device according to the second embodiment. Figure 5 It is an explanatory diagram for explaining a specific example of a method for detecting a short-circuit fault of a reverse connection protection relay according to the second embodiment. DETAILED DESCRIPTION

[0010] Hereinafter, the embodiments will be described with reference to the drawings. The same reference numerals are given to the common or corresponding elements in the drawings, and the description thereof will be cited unless otherwise specified. <First Embodiment> Hereinafter, a first embodiment will be described with reference to the drawings. Figure 1 1 is a circuit diagram showing a configuration example of the electronic control device 1 according to the present embodiment. Figure 1 In the example, it is assumed that the electronic control device 1 is mounted on the same vehicle (not shown) together with the power supply 8, the power switch 9 and the motor 7, and is used for the motion control of the vehicle's motion mechanism. The power switch 9 controls whether power is to be supplied from the power supply 8 to the electronic control device 1. The power switch 9, for example, receives an operation from a user, and generates a switch control signal indicating whether power is to be supplied according to the received operation. The power switch 9 switches whether power is to be supplied from the power supply 8 to the electronic control device 1 according to the generated switch control signal, and outputs the generated switch control signal to the electronic control device 1. The switch control signal provided from the power switch 9 is used to indicate whether power is to be supplied from the power supply 8 to the electronic control device 1.

[0011] The power source 8 and the power switch 9 can use a battery and an ignition switch, respectively. The battery is a storage battery that can supply DC power to the electronic control device 1. The driver of the vehicle can be the main user of the electronic control device 1. The ignition switch generates an ignition signal as an example of a switch control signal. The ignition signal is used to control the start (on) or stop (off) of the vehicle's actuation mechanism. The vehicle's actuation mechanism includes, for example, an electric power steering (EPS: Electric Power Steering), and the motor 7 constitutes a part of the actuation mechanism.

[0012] The electronic control device 1 includes a motor drive circuit 5 as a load that consumes the power supplied from the power supply 8. The motor drive circuit 5 drives to supply power from the power supply 8 to the motor 7. The motor 7 also functions as a load that consumes the power supplied from the power supply 8. The number of motors 7 included in the vehicle's motion mechanism is not limited to one, and may be two or more. In this case, the motor drive circuit 5 supplies the power required for the operation of each motor 7. However, in the following description, the case where the number of motors 7 is one is mainly used.

[0013] The electronic control device 1, the power supply 8, the power switch 9 and the motor 7 can be produced or transferred separately. In addition, the electronic control device 1, the power supply 8, the power switch 9 and the motor 7 are sometimes loaded and unloaded from the vehicle during maintenance, inspection or repair. For example, the positive terminal and the negative terminal of the battery as the power supply 8 are connected to the electronic control device 1 using a power plug (not shown). During the battery replacement operation, the polarity of the battery as a DC power supply may be incorrectly connected to the power plug. The situation of connecting with a polarity different from the predetermined polarity is called reverse connection. If the battery is connected with the wrong polarity, the current from the battery flows in the reverse direction in the electronic control device 1. The reverse flow of current becomes a cause of damage or failure of the electronic control device 1. In order to protect against the influence of reverse connection, the electronic control device 1 is equipped with a reverse connection protection relay 2. As described below, the electronic control device 1 can autonomously determine the state of the reverse connection protection relay 2.

[0014] The electronic control device 1 includes a reverse connection protection relay 2 , a voltage detection unit 3 , a control device 4 , a motor drive circuit 5 , a power output holding circuit 6 , and a power supply circuit 10 . The reverse connection protection relay 2 protects the motor drive circuit 5 from the influence of the reverse flow of current that may be generated when the power supply 8 is reversely connected. The reverse connection protection relay 2 includes a switch element 2s and a rectifier element 14. The switch element 2s and the rectifier element 14 are connected in parallel. That is, at one end of the reverse connection protection relay 2, one end of the rectifier element 14 is electrically connected to one end of the switch element 2s. At the other end of the reverse connection protection relay 2, the other end of the rectifier element 14 is electrically connected to the other end of the switch element 2s. One end of the reverse connection protection relay 2 is connected to the negative electrode of the power supply 8.

[0015] The opening and closing of both ends of the switch element 2s are controlled according to the switch control signal applied to the switch element 2s from the power switch 9. Whether the switch element 2s is turned on from one end to the other end is controlled to be linked to the presence or absence of power supply from the power supply 8 indicated by the switch control signal to the electronic control device 1. Even if it is assumed that the polarity of the power supply 8 is connected opposite to the polarity shown in the figure, the current flowing from the power supply 8 to the motor drive circuit 5 can be cut off by using the reverse connection protection relay 2. Therefore, the motor drive circuit 5 is protected from the influence of the reverse flow of current.

[0016] As the switch control signal, a digital electrical signal indicating whether power supply from the power supply 8 is required may also be used according to whether the voltage is a high voltage or a low voltage. The high voltage and the low voltage respectively represent the higher voltage and the lower voltage of the voltage in the two stages. If there is no signal indicating that the voltage is a high voltage, the detected voltage may be a low voltage. In the present application, the high voltage is sometimes marked as High. The low voltage is sometimes marked as Low.

[0017] The switch element 2s is, for example, a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). A MOSFET generally includes a source, a drain, and a gate. The MOSFET has a source terminal, a drain terminal, and a gate terminal in the source region, the drain region, and the gate region, respectively. The source terminal and the drain terminal of the MOSFET as the switch element 2s are connected to the rectifier element 14 as one end and the other end, respectively. A switch control signal input from the power switch 9 is applied to the gate terminal.

[0018] In addition, the MOSFET used as the switching element 2s may be any type of MOSFET such as an n-type MOSFET or a p-type MOSFET. This embodiment illustrates the case where an n-type MOSFET is used as the switching element 2s. The n-type MOSFET is provided with a silicon oxide film and a gate electrode in a gate region provided on a p-type semiconductor substrate. In the drain region and the source region, an n-type semiconductor is provided on a p-type semiconductor substrate, respectively. The n-type semiconductor is generated by ion implantation of impurities having a higher concentration than the p-type semiconductor.

[0019] The rectifying element 14 conducts the current from one end to the other end and cuts off the current from the other end to one end. The rectifying element 14 is, for example, a diode. A diode generally includes an anode (positive electrode) and a cathode (negative electrode). The diode as the rectifying element 14 has an anode and a cathode as one end and the other end connected to the switching element 2s.

[0020] As the rectifying element 14, for example, a parasitic diode may also be used. A parasitic diode is also called a body diode. The parasitic diode is configured to have a pn junction between the source region and the drain region of an n-type MOSFET. The pn junction is formed by configuring an n-type semiconductor and a p-type semiconductor in the source region and configuring an n-type semiconductor in the drain region so that it does not contact the p-type semiconductor. As the rectifying element 14, a parasitic diode configured as a MOSFET as a switching element 2s may also be used. Thus, as the reverse connection protection relay 2, a MOSFET formed by the switching element 2s and the rectifying element 14 may be used.

[0021] The voltage detection unit 3 detects the voltage at one end of the reverse connection protection relay 2. As described later, the voltage detected with reference to the reference potential GND_PCB is equivalent to the potential difference between the two ends of the reverse connection protection relay 2. The voltage detection unit 3 generates an electrical signal representing the detected voltage, and outputs the generated electrical signal to the control device 4 as a detection voltage signal.

[0022] The control device 4 consumes the power supplied from the power supply 8 via the power switch 9 and the power circuit 10, and executes and controls various processes for exerting the functions of the electronic control device 1. The control device 4 includes, for example, a CPU (Central Processing Unit). The control device 4 determines the state of the reverse connection protection relay 2 based on the detection voltage signal input from the voltage detection unit 3. The control device 4 includes, for example, an A / D (Analog to Digital) converter. The A / D converter converts the input analog detection voltage signal into a digital detection voltage signal, and determines the state of the reverse connection protection relay 2 based on the voltage value represented by the converted detection power signal. As the state of the reverse connection protection relay 2, for example, one or both of the presence or absence of an open circuit fault and the presence or absence of a short circuit fault are detected. A specific example of a method for determining the state of the reverse connection protection relay 2 will be described later.

[0023] The control device 4 may also obtain a notification signal for notifying the determined state, and output the obtained notification signal to the notification unit 16. The notification unit 16 notifies the state of the reverse connection protection relay 2 based on the notification signal input from the control device 4. The notification unit 16 may be, for example, a component such as a light emitting diode and a speaker that can prompt information to the user. When a light emitting diode or a speaker is used as the notification unit 16, DC power and an audio signal are used respectively. The light emitting diode emits light based on the DC power provided from the control device 4. The speaker plays based on the audio signal input from the control device 4. As the notification unit 16, for example, a warning light (warning light), an audio speaker, etc. provided in front of the driver's seat of the vehicle may also be applied. The notification unit 16 may be integrated with the electronic control device 1 or may be constructed separately.

[0024] The control device 4 controls the operation of the motor drive circuit 5 according to a known control method. For example, the control device 4 controls the motor drive circuit 5 according to the ignition signal input to the device. When the voltage of the ignition signal becomes High, the control device 4 controls the motor drive circuit 5 to operate the motor 7. At this time, the control device 4 generates a drive control signal instructing the operation of the motor 7, and outputs the generated drive control signal to the motor drive circuit 5. When the voltage of the ignition signal becomes Low, the control device 4 controls the motor drive circuit 5 to stop the operation of the motor 7. At this time, the control device 4 stops outputting the drive control signal to the motor drive circuit 5.

[0025] Various signals are input as vehicle-side input signals from devices provided in the vehicle to the control device 4. Vehicle-side input signals include torque signals from a torque sensor for detecting steering operation, vehicle speed signals from a vehicle speed sensor, etc. The control device 4 may also perform computational processing and drive instructions for driving the motion mechanism of the vehicle using the vehicle-side input signals.

[0026] The motor drive circuit 5 drives the motor 7 according to the control from the control device 4. As the power supply state, for example, it indicates whether it is necessary to supply power to the motor 7. When a drive control signal indicating that the motor 7 is to be operated is input from the control device 4, the motor drive circuit 5 supplies power from the power supply 8 to the motor 7. When no drive control signal is input from the control device 4, the motor drive circuit 5 stops the power supply from the power supply 8 to the motor 7. The motor drive circuit 5 has, for example, a bridge circuit and a switching element for a motor relay. The bridge circuit includes a high-side switching element and a low-side switching element for supplying power to each of one or more coils of the motor 7. The switching element for the motor relay cuts off the power supplied to the motor 7 when the drive control signal indicates that the motor 7 is not to be operated.

[0027] When a switch control signal is input from the power switch 9 or a power request signal is input from the control device 4, the power output holding circuit 6 outputs an operation permission signal to the power circuit 10. The power request signal is an electrical signal for indicating that power supply is required. The power request signal sets the voltage to High, indicating that power supply is required. The operation permission signal is an electrical signal for instructing to maintain the operation voltage of the control device 4. The operation permission signal sets the voltage to High, indicating that the operation voltage is maintained. The control device 4 outputs the power request signal to the power output holding circuit 6 during the operation.

[0028] The power output holding circuit 6 has, for example, a diode OR structure. The power output holding circuit 6 has, for example, two diodes and one resistor element, and one end of each diode becomes an input end of the power output holding circuit 6. The other end of each diode is connected to one end of the resistor element, becoming an output end of the power output holding circuit 6. The other end of the resistor element is grounded.

[0029] According to this structure, when the voltage of the switch control signal input from the power switch 9 changes from High to Low, the power circuit 10 can maintain the operating voltage of the control device 4. In addition, the power output holding circuit 6 and the power circuit 10 can also be respectively equipped with a battery for storing the power supplied from the power supply 8. When the power from the power supply 8 is cut off, the operation permission signal from the power output holding circuit 6 is maintained to be output. At this time, the power supply from the battery of the power circuit 10 to the control device 4 is carried out. Therefore, it is possible to prevent the power supply from the power supply 8 via the power circuit 10 from being cut off instantly during the operation of the control device 4. Therefore, it is possible to ensure opportunities such as stopping the operation of the motor drive circuit 5 by the control device 4 and the termination processing of the control device 4 itself. In the termination processing, for example, a write processing of writing the internal data of the control device 4 at that time into the memory it has. Just after the voltage of the switch control signal changes from High to Low, the control device 4 does not stop the operation immediately, but can stop the operation at a specified timing.

[0030] After the end processing is completed, the control device 4 stops outputting the power request signal to the power output holding circuit 6. When the input of the switch control signal from the power switch 9 and the input of the power request signal from the control device 4 are stopped, the power output holding circuit 6 stops outputting the operation permission signal to the power circuit 10. When the power is not supplied from the power supply 8 via the power switch 9 and the operation permission signal from the power output holding circuit 6 is not input, the power circuit 10 stops holding the operation voltage. At this time, the power supply from the power circuit 10 to the control device 4 is stopped.

[0031] Next, a circuit configuration example of the reverse connection protection relay 2 and its surroundings according to the present embodiment will be described. Figure 2 2 is a circuit diagram showing an example of a circuit configuration around the reverse connection protection relay 2 according to the present embodiment. Figure 2 In the example, the switching element 2s is a MOSFET, and the rectifier element 14 is a parasitic diode formed on the MOSFET. The reverse connection protection relay 2 is configured to have a MOSFET. The gate terminal of the MOSFET as the switching element 2s is connected to the power switch 9 via the resistor element 12 and the rectifier element 11. The gate terminal and the source terminal of the MOSFET are connected to the anode and the cathode of the Zener diode 13, respectively. The switching control signal provided from the power switch 9 is applied to the gate terminal of the MOSFET. The rectifier element 11 is a charge retention diode for retaining charge when the voltage of the switching control signal is Low. The resistor element 12 is a current limiting resistor for preventing excessive current. The purpose of the Zener diode 13 is to avoid the reverse flow of current caused by the switching control signal and protect the motor drive circuit 5.

[0032] according to Figure 2 In the structure, when the voltage of the switch control signal is High, the source terminal and drain terminal of the MOSFET as the switch element 2s are turned on (ON). When the voltage of the switch control signal is Low, the source terminal and drain terminal of the MOSFET are cut off (OFF). Figure 2 In the example of FIG. 1 , the rectifier element 11, the resistor element 12, and the Zener diode 13 are not essential. A part or all of the rectifier element 11, the resistor element 12, and the Zener diode 13 may be omitted or replaced by other components.

[0033] Next, a specific example of a method of determining the state of the reverse connection protection relay 2 will be described. Figure 3 1 is an explanatory diagram for explaining a specific example of a method for determining the state of the reverse connection protection relay 2 involved in the present embodiment. First, a specific example of a method for detecting an open circuit fault as the state of the reverse connection protection relay 2 is described. The open circuit fault of the reverse connection protection relay 2 refers to a fault in which both ends of the switch element 2s are cut off (OFF) when they should be turned on (ON). In the following description, it is assumed that power is initially supplied from the power supply 8 to the power supply circuit 10 via the power switch 9, the control device 4 is in operation, and the motor drive circuit 5 is not in operation.

[0034] Figure 3 Indicates the time changes of the switch control signal, the state of the reverse connection protection relay, the action permission signal, and the action state of the control device. In the example shown in the figure, the voltage of the switch control signal provided by the power switch 9 is initially High. In the case where an open circuit fault does not occur, the two ends of the reverse connection protection relay 2 are turned on (ON). Therefore, when an open circuit fault occurs, the current flowing from the positive terminal of the power supply 8 to the negative terminal via the switch element 2s becomes a state where the connection between the two ends of the reverse connection protection relay 2 is cut off (OFF). Therefore, the current flowing from the positive terminal of the power supply 8 to the negative terminal passes through the rectifier element 14 connected in parallel with the switch element 2s. Therefore, the potential difference generated at the two ends of the reverse connection protection relay 2 is different when the current passes through the switch element 2s and when the current passes through the rectifier element 14.

[0035] As an example, assume that the resistance between the drain and source of the MOSFET as the switching element 2s is 1mΩ, the forward voltage Vf of the parasitic diode as the rectifying element 14 is 700mV, and the power consumption of the electronic control device 1 is 1A. When the current passes through the MOSFET, the potential difference is 1mV. When the current passes through the parasitic diode, the potential difference is equivalent to its forward voltage, that is, 700mV. The forward voltage depends on the characteristics of each rectifying element 14, but it is a value that is sufficiently larger than the potential difference when the current passes through the switching element 2s. In order to be able to detect the voltage equivalent to the potential difference by the voltage detection unit 3, it is sufficient to set the reference potential in advance.

[0036] like Figure 1 As shown, the reference potential GND of the voltage detection unit 3 is set to be equal to the potential of the negative electrode of the power supply 8. The reference potential GND_PCB of the control components including the power supply circuit 10 and the control device 4 is set to be equal to the potential between the reverse connection protection relay 2 and the motor drive circuit 5. The position where the reference potential GND is set and the setting position of the reference potential GND_PCB are separated across both ends of the reverse connection protection relay 2.

[0037] As described above, the potential difference generated between the reference potential GND and the reference potential GND_PCB is significantly different when an open circuit fault occurs in the reverse connection protection relay 2 and when an open circuit fault does not occur. Therefore, the control device 4 determines whether the switch element 2s has an open circuit fault based on the detection voltage signal input from the voltage detection unit 3. The voltage based on the reference potential GND_PCB becomes the potential difference between the two ends of the reverse connection protection relay 2. More specifically, the control device 4 compares the voltage represented by the detection voltage signal with a pre-set open circuit fault threshold, and can determine whether there is an open circuit fault based on whether the voltage represented by the detection voltage signal is higher than the open circuit fault threshold. As the open circuit fault threshold, it is sufficient to set it between the voltage (potential difference) detected when an open circuit fault occurs and the voltage (potential difference) detected when an open circuit fault does not occur.

[0038] In addition, when the motor 7 is driven in a state where the reverse connection protection relay 2 has an open circuit fault, the drive current passes through the rectifier element 14. The power consumption of the rectifier element 14 is equivalent to the product of the potential difference between the two ends of the rectifier element 14 and the drive current. This power consumption is greater than the power consumption of the switch element 2s when the drive current passes through the switch element 2s. The increase in heat generation can lead to abnormal heating, which may become a cause of failure, smoke or fire. Therefore, the control device 4 may also determine whether the reverse connection protection relay 2 has an open circuit fault before the operation of the motor drive circuit 5 begins. In the case where it is determined that an open circuit fault has occurred, the control device 4 may not output a drive control signal to the motor drive circuit 5 regardless of whether an ignition signal is input. By not operating the motor drive circuit 5, abnormal heating caused by powering the rectifier element 14 can be avoided.

[0039] Next, a specific example of a method for detecting a short-circuit fault of the reverse connection protection relay 2 is described. A short-circuit fault of the reverse connection protection relay 2 refers to a fault in which the switch element 2s is turned on (ON) when it should be turned off (OFF). Figure 3 As shown, at time T0, the voltage of the switch control signal from the power switch 9 changes from High to Low. At this time, the voltage of the action permission signal output from the power output holding circuit 6 is maintained at High. Therefore, even after time T0, the action of the control device 4 continues. The control device 4 stops the action of the motor drive circuit 5 and performs the termination processing of the device. Then, at time T1, the control device 4 stops the action. At this time, the voltage of the action permission signal output from the power output holding circuit 6 changes from High to Low. During the output holding period from time T0 to time T1, the control device 4 can ensure the opportunity to perform fault detection of the reverse connection protection relay 2.

[0040] During the output holding period, the voltage of the control signal becomes Low, so if there is no short-circuit fault, the two ends of the switch element 2s should be cut off (OFF). Therefore, the current flowing from the positive terminal of the power supply 8 to the negative terminal passes through the rectifier element 14. On the other hand, in the case of a short-circuit fault, the current flowing from the positive terminal of the power supply 8 to the negative terminal passes through the switch element 2s. In this way, the potential difference between the two ends of the reverse connection protection relay 2 is different depending on whether the current passes through the rectifier element 14 or the switch element 2s.

[0041] As an example, assume that the resistance between the drain and source of the MOSFET as the switching element 2s is 1 mΩ, the forward voltage Vf of the parasitic diode as the rectifying element 14 is 700 mV, and the power consumption of the electronic control device 1 is 1 A. When the current passes through the MOSFET, the potential difference is 1 mV. When the current passes through the parasitic diode, the potential difference is equivalent to its forward voltage, that is, 700 mV.

[0042] Therefore, the control device 4 determines whether the switch element 2s has a short-circuit fault based on the detection voltage signal input from the voltage detection unit 3. The detection voltage signal represents the voltage detected by the voltage detection unit 3. More specifically, the control device 4 compares the voltage represented by the detection voltage signal with a preset short-circuit fault threshold value, and can determine whether there is a short-circuit fault based on whether the voltage represented by the detection voltage signal is lower than the short-circuit fault threshold value. As the short-circuit fault threshold value, it is sufficient to set it between the voltage (potential difference) detected when the short-circuit fault occurs and the voltage (potential difference) detected when the short-circuit fault does not occur. In addition, as described above, it is sufficient to set the reference potential GND of the voltage detection unit 3 to be equal to the potential of the negative pole of the power supply 8. In addition, the reference potential GND_PCB of the control components including the power supply circuit 10 and the control device 4 is pre-set to be equal to the potential between the reverse connection protection relay 2 and the motor drive circuit 5. Through such a setting, the voltage represented by the detection voltage signal is equivalent to the potential difference between the two ends of the reverse connection protection relay 2.

[0043] When a short-circuit fault is determined, the control device 4, for example, provides DC power as a notification signal for notifying the short-circuit fault to a warning light provided in the vehicle. The warning light emits light according to the DC power from the control device 4. The driver who recognizes the illuminated warning light is notified of the occurrence of a short-circuit fault. As an example of the power switch 9, when an ignition switch is applied, it is protected from the influence of the current generated by the battery connection of the power supply 8 during the period when the ignition is disconnected. The period when the ignition is disconnected is equivalent to the period when the ignition signal with a high voltage is not input. Generally speaking, the battery is not replaced while the vehicle is driving. Therefore, if short-circuit fault detection is performed during the period when the ignition is disconnected, it has sufficient practicality.

[0044] In the above description, the reverse connection protection relay 2 is driven by the switch control signal from the power switch 9 instead of the power supplied from the power supply 8, and the operation voltage of the control device 4 is maintained by the power output holding circuit 6. When the power from the power supply 8 is not supplied, even if the conduction between the two ends of the reverse connection protection relay is cut off by the switch control signal, the operation voltage of the control device 4 is maintained by the power output holding circuit 6. Even in such a case, the control device 4 can be operated to autonomously perform short-circuit fault detection of the reverse connection protection relay 2.

[0045] <Second Embodiment> Hereinafter, the second embodiment will be described with reference to the accompanying drawings. In the following description, the differences from the first embodiment are mainly described. Unless otherwise specified, the description in the first embodiment will be cited for other matters. In addition to the case where the power supply from the power supply 8 is cut off, the electronic control device 1 involved in this embodiment can detect the presence or absence of a short-circuit fault as the state of the reverse connection protection relay 2 even when the power supply from the power supply 8 is started. Then, the opening and closing of the reverse connection protection relay 2 is controlled according to the switch control signal.

[0046] Figure 4 : is a circuit diagram showing a configuration example of the electronic control device 1 according to the present embodiment. The electronic control device 1 according to the present embodiment includes a reverse connection protection relay 2, a voltage detection unit 3, a control device 4, a motor drive circuit 5, a power output holding circuit 6, and a power circuit 10, and further includes a reverse connection protection relay drive control circuit 24. The reverse connection protection relay drive control circuit 24 is provided between the power switch 9 and the reverse connection protection relay 2, and connects them. When a switch control signal indicating that power supply is required is input from the power switch 9 and a switch command signal indicating a switch command is input from the control device 4 to the reverse connection protection relay 2, the reverse connection protection relay drive control circuit 24 outputs a switch control signal indicating that power supply is required to the reverse connection protection relay 2. When a switch control signal indicating that power supply is not required is input from the power switch 9 or a switch command signal indicating a switch command of the reverse connection protection relay 2 is not input from the control device 4, the reverse connection protection relay drive control circuit 24 outputs a switch control signal indicating that power supply is not required to the reverse connection protection relay 2. For example, whether a switch command is required is indicated by whether the voltage of the switch command signal is High or Low.

[0047] Therefore, when the reverse connection protection relay drive control circuit 24 obtains the switch instruction from the control device 4, it can control the opening and closing of the reverse connection protection relay 2 according to the switch control signal from the power switch 9. When the switch instruction is not obtained, the reverse connection protection relay drive control circuit 24 cuts off both ends of the reverse connection protection relay 2 regardless of whether there is a switch control signal with a high input voltage. In this state, the control device 4 can determine whether the reverse connection protection relay 2 has a short-circuit fault based on the voltage represented by the detection power signal input from the voltage detection unit 3. After determining whether there is a short-circuit fault, the control device 4 outputs a switch instruction signal representing the switch instruction of the reverse connection protection relay 2 to the reverse connection protection relay drive control circuit 24. The switch instruction, for example, represents the voltage of the switch instruction signal as High. The control device 4, for example, has a GPIO (General Purpose Input / Output) port, and can use the GPIO to output the switch instruction signal.

[0048] In addition, when the power supply from the power supply circuit 10 starts, the control device 4 performs an initialization process. The initialization process includes, for example, reading of internal data stored in the memory, detection of various devices connected to the device, and other processes. After completing the initialization process, the control device 4 can determine whether there is a short-circuit fault. After determining that there is no short-circuit fault, the control device 4 outputs a switch command signal to the reverse connection protection relay drive control circuit 24. As a result, it becomes possible to control the opening and closing of the reverse connection protection relay 2 based on the switch control signal from the power switch 9. At this stage, the control device 4 can also start controlling the motor drive circuit 5 based on the ignition signal.

[0049] Next, a specific example of a method for detecting a short-circuit fault of the reverse connection protection relay 2 will be described. Figure 5 This is an explanatory diagram for explaining an example of a detection method for a short-circuit fault of the reverse connection protection relay 2 according to the present embodiment. In the following description, it is assumed that initially no power is supplied from the power supply 8 to the power supply circuit 10 via the power switch 9, and the control device 4 and the motor drive circuit 5 are not in operation. Figure 5Indicates the time changes of the switch control signal, the power circuit output, the operating state of the control device 4, the switch command, and the state of the reverse connection protection relay 2. In the example shown in the figure, the voltage of the switch control signal provided by the power switch 9 is initially Low. If no short-circuit fault occurs, the conduction at both ends of the reverse connection protection relay 2 is cut off (OFF). In this state, power is not supplied from the power supply 8 to the power circuit 10 via the power switch 9. Therefore, the voltage of the power supplied from the power circuit 10 to the control device 4 is 0V (OFF). At this time, since the control device 4 does not operate (OFF), the control device 4 does not output the switch command signal (OFF).

[0050] Next, assume that at time T0, the voltage of the switch control signal from the power switch 9 changes from Low to High. At this time, the voltage of the power supplied from the power circuit 10 to the control device 4 starts to rise from 0V (OFF), and at time T1, the control device 4 reaches the specified action voltage (ON). At this time, the voltage is stable, and the initialization process (ON) starts as the action of the control device 4. After the initialization process is completed, at time T2, the control device 4 starts to output a switch command signal (ON) indicating a switch command to the reverse connection protection relay drive control circuit 24. At this time, the reverse connection protection relay drive control circuit 24 starts to output a switch control signal with a voltage of High to the reverse connection protection relay 2. If no short-circuit fault occurs, the two ends of the reverse connection protection relay 2 change from a cut-off state (OFF) to a conductive state (ON). Therefore, during the period from the end of the initialization process to the output of the switch command signal at time T2, the control device 4 can determine whether the reverse connection protection relay 2 has a short-circuit fault based on the voltage value represented by the detection power signal input from the voltage detection unit 3.

[0051] During this period, since the power supply circuit 10 and the control device 4 operate, a current is generated from the positive terminal of the power supply 8 to the negative terminal. If the reverse connection protection relay 2 does not have a short-circuit fault, the two ends of the switch element 2s should be cut off (disconnected). In this state, the generated current passes through the rectifier element 14 connected in parallel with the switch element 2s. When a short-circuit fault occurs, the two ends of the switch element 2s are turned on (ON). Therefore, the current flowing from the positive terminal of the power supply 8 to the negative terminal passes through the switch element 2s. Therefore, the potential difference generated at the two ends of the reverse connection protection relay 2 is different when the current passes through the rectifier element 14 and when the current passes through the switch element 2s.

[0052] As an example, assume that the resistance between the drain and source of the MOSFET as the switching element 2s is 1 mΩ, the forward voltage Vf of the parasitic diode as the rectifying element 14 is 700 mV, and the power consumption of the electronic control device 1 is 1 A. When the current passes through the parasitic diode, the potential difference is equivalent to the forward voltage thereof, that is, 700 mV. When the current passes through the MOSFET, the potential difference is 1 mV.

[0053] Therefore, the control device 4 determines whether the switch element 2s has a short-circuit fault based on the detection voltage signal input from the voltage detection unit 3. More specifically, the control device 4 compares the voltage represented by the detection voltage signal with a preset short-circuit fault threshold, and can determine whether the short-circuit fault exists based on whether the voltage represented by the detection voltage signal is lower than the short-circuit fault threshold. As the short-circuit fault threshold, a value between the voltage when the short-circuit fault occurs and the voltage when the short-circuit fault does not occur can be preset.

[0054] Therefore, according to the reverse connection protection relay drive control circuit 24, the conduction of the reverse connection protection relay 2 can be controlled to be cut off even when power is supplied from the power supply 8. Therefore, even after the control device 4 consumes the power supplied from the power supply 8 and starts to operate, it can determine whether the reverse connection protection relay 2 has a short-circuit fault.

[0055] Next, a modification of the electronic control device 1 of the above-mentioned embodiment is described. The electronic control device 1 may include, for example, any one or any combination of a power switch 9, a motor 7, and a notification unit 16 to form an integrated body. The electronic control device 1 may also include a power supply 8. The electronic control device 1 may have a function of controlling other devices mounted on the vehicle. The other devices may be, for example, any one or any combination of an audio device, an air conditioning device, a navigation device, a driving assistance system, etc. The electronic control device 1 may also be configured as an ECU (Electronic Control Unit).

[0056] The power source 8 is not limited to a mobile power source such as a battery, but may also be a fixed power source. The power supply from the power source 8 to the electronic control device 1 is not limited to wired, but may also be wireless. When a wireless charger is used as the power source 8, the electronic control device 1 may also have a wireless receiver to receive power transmitted from the wireless charger. The load is not limited to the motor drive circuit 5, and may be any other device as long as it consumes the power provided by the power source 8. The device that becomes the load may not necessarily be integrally formed with the electronic control device 1.

[0057] The switch element 2s is not necessarily limited to a MOSFET, and may be another type of bipolar transistor. The rectifier element 14 is not necessarily limited to a diode, and may be a selenium rectifier or the like. As the notification unit 16, a display may be used. The control device 4 may generate a signal that indicates the information indicating the determined state by text, a symbol or an image as the above-mentioned notification signal, and output it to the display. As the notification unit 16, when a speaker is used, a signal that indicates the information indicating the determined state by sound may be generated as the above-mentioned signal, and output it to the speaker. In addition to the information indicating the determined state, the notified information may also include information indicating countermeasures for the state (such as replacement of parts, contact with a sales store, etc.).

[0058] As described above, the electronic control device 1 involved in the present disclosure includes a reverse connection protection relay 2, a voltage detection unit 3 and a control device 4. The reverse connection protection relay 2 has a switching element 2s and a rectifying element 14, and the switching element 2s and the rectifying element 14 are connected in parallel. The negative pole of the rectifying element 14 and the positive pole of the rectifying element 14 are respectively connected to the negative pole of the power supply 8 and the load (for example, the motor drive circuit 5). The load consumes the power provided by the power supply 8. The opening and closing of the switching element 2s is controlled based on a switch control signal indicating whether there is power supply from the power supply. The voltage detection unit 3 detects the potential difference between the two ends of the reverse connection protection relay 2. The control device 4 determines the state of the reverse connection protection relay 2 based on the detected potential difference. Generally, the resistance of the reverse connection protection relay 2 depends on its state. According to this structure, the state of the reverse connection protection relay 2 is determined based on the potential difference generated at both ends of the reverse connection protection relay 2 by the current flowing through the reverse connection protection relay 2 according to the power supply from the power supply 8. Therefore, the state of the reverse connection protection relay 2 can be detected autonomously without increasing the circuit scale or cost.

[0059] The control device 4 may detect the presence or absence of an open circuit fault as the state of the reverse connection protection relay 2 when electric power is supplied from the power supply 8 . According to this configuration, when the reverse connection protection relay 2 is instructed to turn on, it is possible to determine whether an open circuit fault is present based on the potential difference between both ends of the reverse connection protection relay 2 .

[0060] The electronic control device 1 may include a power supply circuit 10 and a power output holding circuit 6. The power supply circuit 10 may also convert the power supply voltage of the power supplied from the power supply 8 into the operating voltage of the control device 4. When the power supply from the power supply 8 is cut off, the power output holding circuit 6 may also keep the power supply circuit 10 at the operating voltage. The control device 4 may also detect the presence or absence of a short circuit fault as the state of the reverse connection protection relay 2. According to this structure, even if the power supply from the power source 8 is cut off, the operating voltage of the control device 4 can be maintained. On the other hand, the conduction of the reverse connection protection relay 2 is controlled to be cut off. The control device 4 can determine whether there is a short-circuit fault based on the potential difference between the two ends of the reverse connection protection relay 2 without stopping the operation.

[0061] The electronic control device 1 may further include a drive control circuit (e.g., a reverse connection protection relay drive control circuit 24). The drive control circuit may also turn on the switch element 2s when power is supplied from the power supply 8 and a switch command is obtained from the control device 4. The control device 4 may also detect the presence or absence of a short-circuit fault as the state of the reverse connection protection relay 2 before power is supplied from the power supply 8 and a switch command is obtained from the control device 4. According to this structure, even if power is supplied from the power supply 8, the conduction of the switch element 2s is cut off at the stage where the switch command is not received from the control device 4. Even before the switch command is input, the control device 4 is operated by the power supply from the power supply 8, thereby being able to determine whether there is a short-circuit fault based on the potential difference between the two ends of the reverse connection protection relay 2.

[0062] The reference potential that is the reference of the operating voltage of the control device 4 and the reference potential of the voltage detection unit 3 may be separated across both ends of the reverse connection protection relay 2 . According to this configuration, by setting the reference potential of the control device 4 at one end of the reverse connection protection relay 2 , the voltage detection unit 3 can detect the voltage at one end of the reverse connection protection relay 2 as the potential difference between both ends of the reverse connection protection relay 2 .

[0063] The switching element 2s may be a MOSFET, and the rectifying element 14 may be a parasitic diode formed by joining the source and drain of the MOSFET. According to this configuration, the reverse connection protection relay 2 is constituted by one MOSFET. Reducing the number of components contributes to miniaturization and cost reduction of the electronic control device 1.

[0064] The load may be the motor drive circuit 5 that drives the motor 7. The switching of the switching element 2s may be controlled based on an ignition signal input from an ignition switch as a switching control signal. According to this structure, the opening and closing of the switch element 2s is linked with the power supply to the motor drive circuit 5 through the ignition switch, which can prevent the current from flowing reversely to the motor drive circuit 5 due to the reverse connection of the power supply 8. In addition, by using the ignition signal in the control of the switch element 2s, the state of the reverse connection protection relay 2 can be detected without delay.

[0065] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments and their modifications. Additions, omissions, substitutions, and other changes to the structure may be made without departing from the gist of the present disclosure. The directions of arrows shown in block diagrams and other drawings are for convenience of explanation and do not limit the direction of the flow of information, data, signals, etc. during installation. Additionally, the present disclosure is not limited by the above description, but only by the scope of the appended claims. Industrial Applicability

[0066] According to the electronic control device and the electronic control method involved in the present disclosure, the state of the reverse connection protection relay 2 is determined based on the potential difference generated at both ends of the reverse connection protection relay 2 by the current flowing through the reverse connection protection relay 2 according to the power supply from the power supply 8. Therefore, the state of the reverse connection protection relay 2 can be detected autonomously without increasing the circuit scale or cost. Description of symbols

[0067] 1…electronic control device, 2…reverse connection protection relay, 2s…switching element, 3…voltage detection unit, 4…control device, 5…motor drive circuit, 6…power output holding circuit, 8…power supply, 9…power switch, 10…power supply circuit, 11…rectifier element, 12…resistor element, 13…zener diode, 14…rectifier element, 24…reverse connection protection relay drive control circuit.

Claims

1. An electronic control device, comprising a reverse connection protection relay, a voltage detection unit and a control device, characterized in that: The reverse connection protection relay includes a switching element and a rectifying element, The switching element and the rectifying element are connected in parallel, The negative electrode of the rectifying element and the positive electrode of the rectifying element are connected to the negative electrode of the power source and the load respectively. the load consumes power supplied from the power source, The opening and closing of the switch element is controlled based on a switch control signal indicating whether or not power is supplied from the power source. The voltage detection unit detects a potential difference between both ends of the reverse connection protection relay. The control device determines the state of the reverse connection protection relay based on the potential difference.

2. The electronic control device according to claim 1, characterized in that The control device detects the presence or absence of an open circuit fault as the state of the reverse connection protection relay when electric power is supplied from the power supply.

3. The electronic control device according to claim 1 or 2, characterized in that: Including power supply circuit and power output holding circuit, The power supply circuit converts the power supply voltage of the electric power supplied from the power supply into an operating voltage of the control device. When the power supply from the power source is cut off, The power output holding circuit causes the power circuit to maintain the operating voltage. The control device detects the presence or absence of a short-circuit fault as the state of the reverse connection protection relay.

4. The electronic control device according to any one of claims 1 to 3, characterized in that: It also includes a drive control circuit, The drive control circuit turns on the switch element when power is supplied from the power source and a switch instruction is received from the control device. The control device detects the presence or absence of a short-circuit fault as a state of the reverse connection protection relay before power is supplied from the power source and a switching command is acquired from the control device.

5. The electronic control device according to any one of claims 1 to 4, characterized in that: A reference potential serving as a reference for an operating voltage of the control device and a reference potential of the voltage detection unit are separated across both ends of the reverse connection protection relay.

6. The electronic control device according to any one of claims 1 to 6, characterized in that: The switching element is a metal oxide semiconductor field effect transistor (MOSFET), The rectifying element is a parasitic diode formed by joining the source and drain of the MOSFET.

7. The electronic control device according to any one of claims 1 to 6, characterized in that: The load is a motor drive circuit that drives a motor, The opening and closing of the switching element is controlled based on an ignition signal input from an ignition switch as the switching control signal.

8. An electronic control method, which is an electronic control method for an electronic control device, wherein the electronic control device comprises a reverse connection protection relay, a voltage detection unit and a control device, The reverse connection protection relay includes a switching element and a rectifying element, The switching element and the rectifying element are connected in parallel, The negative electrode of the rectifying element and the positive electrode of the rectifying element are connected to the negative electrode of the power supply and the load respectively. the load consumes power supplied from the power source, The opening and closing of the switch element is controlled based on a switch control signal indicating whether or not power is supplied from the power source. The electronic control method is characterized by performing the following steps: A first step in which the voltage detection unit detects a potential difference between both ends of the reverse connection protection relay; and A second step in which the control device determines a state of the reverse connection protection relay based on the potential difference.

Images