Electronic control device and electronic control method

Abstract

The present invention comprises a reverse connection protection relay, a voltage detection unit, and a control device. The reverse connection protection relay comprises a switching element and a rectifying element. The switching element and the rectifying element are 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. Opening / closing of the switching element is controlled on the basis of a switching control signal indicating the presence or absence of power supply from the power source. The voltage detection unit detects a potential difference between both ends of the reverse connection protection relay, and the control device determines the state of the reverse connection protection relay on the basis of the potential difference.

Description

[Technical Field]

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

[0002] Patent Document 1 describes an electronic control device that includes 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 that generates a positive power supply voltage, a voltage detection unit that detects the voltage between the positive power supply voltage and the ground of a battery, an A / D conversion unit that A / D converts the voltage output from the voltage detection unit, and a fault diagnosis unit that performs fault diagnosis on the reverse connection protection unit based on the output value output from the A / D conversion unit.Patent Document 1 also describes providing an electronic control device that uses a MOSFET as a reverse connection protection element between a load and ground and can diagnose faults in the reverse connection protection element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-42015 A Summary of the Invention [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 in the MOSFET cannot be detected simply by monitoring the positive power supply voltage. If the battery is reverse-connected during a short circuit fault, current will flow backward. This current backflow can cause the electronic control device to malfunction. To prevent current backflow, it is possible to consider adding a redundant reverse polarity protection relay or adding a driver to apply a positive power supply voltage to the MOSFET gate. However, these measures require additional elements or peripheral circuits, which increases the circuit size and cost.

[0005] An object of the present disclosure is to provide an electronic control device and an electronic control method that solve the above-mentioned problems. [Means for solving the problem]

[0006] According to a first aspect, the electronic control device includes a reverse connection protection relay, a voltage detection unit, a control device, a power supply circuit; a power supply output holding circuit; the reverse connection protection relay comprises a switching element and a rectifying element, the switching element and the rectifying element are connected in parallel, a negative electrode of the rectifying element and a positive electrode of the rectifying element are connected to a negative electrode of a power supply and a load, respectively, the load consumes power supplied from the power supply, and opening and closing of the switching element is controlled based on a switching control signal indicating presence or absence of power supply from the power supply, the power supply circuit converts a power supply voltage of the power supplied from the power supply into an operating voltage of the control device, and when the power supply is cut off, the power supply output holding circuit causes the power supply circuit to hold the operating voltage; The voltage detection unit detects a potential difference between both ends of the reverse connection protection relay, and the control device determines a state of the reverse connection protection relay based on the potential difference. to detect the presence or absence of a short circuit fault. .

[0007] According to a second aspect, a reverse connection protection relay, a voltage detection unit, and a control device are provided. a power supply circuit; a power supply output holding circuit; the reverse connection protection relay comprises 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 a power source and a load, respectively, the load consumes power supplied from the power source, and opening and closing of the switching element is controlled based on a switching control signal indicating whether or not power is being supplied from the power source. The power supply circuit converts the power supply voltage supplied from the power supply into an operating voltage for the control device. An electronic control method in an electronic control device, when the power supply is cut off, the power supply output holding circuit causes the power supply circuit to hold the operating voltage; The voltage detection unit executes a first step of detecting a potential difference across the reverse connection protection relay, and the control device executes a second step of determining a state of the reverse connection protection relay based on the potential difference. [Effects of the Invention]

[0008] According to the present disclosure, a fault in a reverse polarity protection relay can be detected economically. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a circuit diagram showing an example of the configuration of an electronic control device according to a first embodiment. [Figure 2] 1 is a circuit diagram showing an example of a circuit configuration around a reverse connection protection relay according to a first embodiment. [Figure 3] 3 is an explanatory diagram for explaining a specific example of a method for determining the state of the reverse connection protection relay according to the first embodiment. FIG. [Figure 4] FIG. 6 is a circuit diagram showing a configuration example of an electronic control device according to a second embodiment. [Figure 5] 10 is an explanatory diagram for explaining a specific example of a method for detecting a short-circuit fault in a reverse connection protection relay according to a second embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. Elements common to or corresponding to the various drawings are designated by the same reference numerals, and the same explanations are incorporated unless otherwise specified. First Embodiment A first embodiment will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an example of the configuration of an electronic control device 1 according to this embodiment. In the example of FIG. 1, it is assumed that the electronic control device 1 is mounted on the same vehicle (not shown) together with a power supply 8, a power switch 9, and an electric motor 7 and is used to control the operation of an operating mechanism of the vehicle. The power switch 9 controls whether or not to supply power from the power supply 8 to the electronic control device 1. The power switch 9 receives, for example, a user operation and generates a switching control signal indicating whether or not to supply power in accordance with the received operation. The power switch 9 switches whether or not to supply power from the power supply 8 to the electronic control device 1 in accordance with the generated switching control signal and outputs the generated switching control signal to the electronic control device 1. Whether or not to supply power from the power supply 8 to the electronic control device 1 is instructed using the switching control signal provided by the power switch 9.

[0011] A battery and an ignition switch can be applied as the power supply 8 and the power switch 9, respectively. The battery is a storage battery capable of supplying 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 switching control signal. The ignition signal is used to control the start (ON) or stop (OFF) of an operating mechanism of the vehicle. The operating mechanism of the vehicle includes, for example, electric power steering (EPS). The electric motor 7 forms part of the operating mechanism.

[0012] The electronic control device 1 includes an electric motor drive circuit 5 as a load that consumes power supplied from a power source 8. The electric motor drive circuit 5 supplies power from the power source 8 to an electric motor 7 to drive it. The electric motor 7 also functions as a load that consumes power supplied from the power source 8. The number of electric motors 7 provided in the vehicle operating mechanism is not limited to one, but can be two or more. In this case, the electric motor drive circuit 5 supplies the power required to operate each electric motor 7. However, the following description will mainly focus on the case where the number of electric motors 7 is one.

[0013] The electronic control unit 1, power supply 8, power switch 9, and electric motor 7 may be manufactured or sold separately. Furthermore, the electronic control unit 1, power supply 8, power switch 9, and electric motor 7 may be detached from the vehicle for maintenance, inspection, or repair. For example, the positive and negative terminals of a battery serving as the power supply 8 are connected to the electronic control unit 1 using a power plug (not shown). During battery replacement, the battery, which is a DC power source, may be connected to the power plug with the wrong polarity. Connecting a battery with a polarity different from the predetermined polarity is called reverse connection. Connecting a battery with the wrong polarity causes a reverse current flow from the battery in the electronic control unit 1. This reverse current flow can cause a malfunction or breakdown of the electronic control unit 1. To protect against reverse connection, the electronic control unit 1 includes a reverse polarity protection relay 2. As described below, the electronic control unit 1 can autonomously determine the state of the reverse polarity 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, an electric 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 reverse current that may occur when the power supply 8 is reversely connected. The reverse connection protection relay 2 includes a switching element 2s and a rectifying element 14. The switching element 2s and the rectifying element 14 are connected in parallel. That is, one end of the reverse connection protection relay 2 is electrically connected to one end of the rectifying element 14 and one end of the switching element 2s. The other end of the reverse connection protection relay 2 is electrically connected to the other end of the rectifying element 14 and the other end of the switching element 2s. One end of the reverse connection protection relay 2 is connected to the negative pole of the power supply 8.

[0015] The opening and closing of both ends of the switching element 2s is controlled based on a switching control signal applied to the switching element 2s from the power switch 9. The presence or absence of conduction from one end of the switching element 2s to the other is controlled so as to be linked to the presence or absence of power supply from the power supply 8 to the electronic control device 1, as indicated by the switching control signal. Even if the polarity of the power supply 8 is connected in the opposite direction to the polarity shown in the figure, the reverse polarity protection relay 2 cuts off the current flowing from the power supply 8 to the motor drive circuit 5. Therefore, the motor drive circuit 5 is protected from reverse current flow.

[0016] The switching control signal may be a digital electrical signal that indicates whether power is supplied from the power supply 8 depending on whether the voltage is high or low. The high voltage and low voltage refer to the higher and lower voltages, respectively, of two voltage levels. If a signal that causes the voltage to be high is not supplied, the detected voltage may be low. In this application, high voltage may be referred to as high, and low voltage may be referred to as low.

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

[0018] 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. In the n-type MOSFET, a silicon oxide film and a gate electrode are disposed in a gate region set on a p-type semiconductor substrate. The drain region and source region each include an n-type semiconductor on a p-type semiconductor substrate. The n-type semiconductor is produced by ion implantation of impurities at a higher concentration than the p-type semiconductor.

[0019] The rectifying element 14 conducts current from one end to the other end and blocks current from the other end to one end. The rectifying element 14 is, for example, a diode. A diode generally has an anode and a cathode. The anode and cathode of the diode serving as the rectifying element 14 are connected to the switching element 2s at one end and the other end, respectively.

[0020] For example, a parasitic diode may be used as the rectifier element 14. A parasitic diode is also called a body diode. A parasitic diode is formed by a p-n junction between the source region and the drain region of an n-type MOSFET. The p-n junction is formed by arranging a p-type semiconductor together with an n-type semiconductor in the source region, and arranging an n-type semiconductor in the drain region so that the p-type semiconductor is not in contact with the n-type semiconductor. A parasitic diode formed in a MOSFET as the switching element 2s may be used as the rectifier element 14. This allows a MOSFET in which the switching element 2s and the rectifier element 14 are integrally formed to be used as the reverse polarity protection relay 2.

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

[0022] The control device 4 consumes power supplied from a power source 8 via a power switch 9 and a power circuit 10, and executes and controls various processes to enable the electronic control device 1 to function. 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 a detected 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 detected voltage signal into a digital detected voltage signal, and determines the state of the reverse connection protection relay 2 based on the voltage value indicated by the converted detected power signal. The state of the reverse connection protection relay 2 may be, for example, the presence or absence of an open circuit fault, the presence or absence of a short circuit fault, or both. Specific examples of methods for determining the state of the reverse connection protection relay 2 will be described later.

[0023] The control device 4 may acquire a notification signal for notifying the determined state and output the acquired 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 light-emitting diode, a speaker, or other component capable of presenting information to the user. When a light-emitting diode or a speaker is used as the notification unit 16, DC power and an acoustic signal are used, respectively. The light-emitting diode emits light in response to the DC power supplied from the control device 4. The speaker emits sound based on the acoustic signal input from the control device 4. The notification unit 16 may be, for example, a warning light provided in front of the driver's seat of the vehicle, an audio speaker, or the like. The notification unit 16 may be integrated with the electronic control device 1 or configured separately.

[0024] The control device 4 controls the operation of the electric motor drive circuit 5 based on a known control method. The control device 4 controls the electric motor drive circuit 5 based on, for example, an ignition signal input to the control device 4. When the voltage of the ignition signal becomes high, the control device 4 causes the electric motor drive circuit 5 to operate the electric motor 7. At this time, the control device 4 generates a drive control signal that instructs the electric motor 7 to operate, and outputs the generated drive control signal to the electric motor drive circuit 5. When the voltage of the ignition signal becomes low, the control device 4 causes the electric motor drive circuit 5 to stop the operation of the electric motor 7. At this time, the control device 4 stops outputting the drive control signal to the electric motor drive circuit 5.

[0025] Various signals are input to the control device 4 as vehicle-side input signals from devices provided in the vehicle. The vehicle-side input signals include a torque signal from a torque sensor that detects steering operation, a vehicle speed signal from a vehicle speed sensor, etc. The control device 4 may use the vehicle-side input signals to execute calculation processing and drive instructions for driving the operating mechanisms of the vehicle.

[0026] The motor drive circuit 5 drives the motor 7 under control of the control device 4. The power supply state is indicated, for example, by whether or not power is to be supplied to the motor 7. When a drive control signal indicating that the motor 7 needs to operate is input from the control device 4, the motor drive circuit 5 supplies power from the power source 8 to the motor 7. When a drive control signal is not input from the control device 4, the motor drive circuit 5 stops the power supply from the power source 8 to the motor 7. The motor drive circuit 5 includes, for example, a bridge circuit and a motor relay switching element. The bridge circuit includes a high-side switching element and a low-side switching element for supplying power to one or more coils provided in the motor 7. The motor relay switching element cuts off the power supplied to the motor 7 when the drive control signal indicates that the motor 7 should not operate.

[0027] The power supply output holding circuit 6 outputs an operation permission signal to the power supply circuit 10 when a switching control signal is input from the power switch 9 or when a power request signal is input from the control device 4. The power request signal is an electrical signal indicating a need for power supply. The power request signal indicates a need for power supply by setting the voltage to High. The operation permission signal is an electrical signal instructing the control device 4 to maintain its operating voltage. The operation permission signal indicates a need for power supply by setting the voltage to High. The control device 4 outputs the power request signal to the power supply output holding circuit 6 during operation.

[0028] The power supply output holding circuit 6 has, for example, a diode OR configuration. The power supply output holding circuit 6 includes, for example, two diodes and one resistive element, and one end of each diode serves as an input terminal of the power supply output holding circuit 6. The other end of each diode is connected to one end of the resistive element and serves as an output terminal of the power supply output holding circuit 6. The other end of the resistive element is grounded.

[0029] According to this configuration, when the voltage of the switching control signal input from the power switch 9 changes from high to low, the power supply circuit 10 can be made to maintain the operating voltage of the control device 4. The power output holding circuit 6 and the power supply circuit 10 may each include a storage battery for storing power supplied from the power supply 8. When power from the power supply 8 is cut off, the output of the operation permission signal from the power output holding circuit 6 is maintained. At this time, power is supplied to the control device 4 from the storage battery of the power supply circuit 10. This prevents the power supply from the power supply 8 via the power supply circuit 10 from being immediately cut off while the control device 4 is operating. This ensures opportunities for the control device 4 to stop the operation of the motor drive circuit 5 and to perform termination processing of the control device 4 itself. The termination processing includes, for example, writing the internal data of the control device 4 at that time to its own memory. Immediately after the voltage of the switching control signal changes from high to low, the control device 4 can terminate its operation at a predetermined timing, rather than immediately terminating its operation.

[0030] After completing the termination process, the control device 4 stops outputting the power request signal to the power supply output holding circuit 6. The power supply output holding circuit 6 stops outputting the operation permission signal to the power supply circuit 10 when the input of the switching control signal from the power switch 9 and the input of the power request signal from the control device 4 are both stopped. The power supply circuit 10 stops holding the operating voltage when power is not supplied from the power supply 8 via the power switch 9 and the operation permission signal is not input from the power supply output holding circuit 6. At this time, the supply of power from the power supply circuit 10 to the control device 4 stops.

[0031] Next, an example of a circuit configuration around the reverse connection protection relay 2 according to this embodiment will be described. FIG. 2 is a circuit diagram showing an example of a circuit configuration around the reverse connection protection relay 2 according to this embodiment. In the example of FIG. 2, the switching element 2s is a MOSFET, and a parasitic diode formed in the MOSFET is used as the rectifier element 14. The reverse connection protection relay 2 is composed of one MOSFET. The gate terminal of the MOSFET serving as the switching element 2s is connected to the power switch 9 via a resistor element 12 and a rectifier element 11. The anode and cathode of a Zener diode 13 are connected to the gate and source terminals of the MOSFET, respectively. A switching control signal supplied from the power switch 9 is applied to the gate terminal of the MOSFET. The rectifier element 11 is a charge-retaining diode that retains charge when the voltage of the switching control signal becomes low. The resistor element 12 is a current-limiting resistor that prevents excessive current. The Zener diode 13 aims to protect the motor drive circuit 5 by preventing reverse current flow due to the switching control signal.

[0032] According to the configuration of Fig. 2, during a period when the voltage of the switching control signal is high, the source terminal and drain terminal of the MOSFET serving as the switching element 2s are conductive (ON). During a period when the voltage of the switching control signal is low, the source terminal of the MOSFET is disconnected from the drain terminal (OFF). Note that in the example of Fig. 2, the rectifier element 11, the resistor element 12, and the Zener diode 13 are not essential. Some or all of the rectifier element 11, the resistor element 12, and the Zener diode 13 may be omitted or replaced with other components.

[0033] Next, a specific example of a method for determining the state of the reverse connection protection relay 2 will be described. FIG. 3 is an explanatory diagram for explaining a specific example of a method for determining the state of the reverse connection protection relay 2 according to this embodiment. First, a specific example of a method for detecting an open fault as a state of the reverse connection protection relay 2 will be described. An open fault in the reverse connection protection relay 2 refers to a fault in which both ends of the switching element 2s are disconnected (OFF) when they should be connected (ON). In the following explanation, it is initially assumed that power is supplied from the power source 8 to the power supply circuit 10 via the power switch 9, the control device 4 is operating, and the motor drive circuit 5 is not operating.

[0034] FIG. 3 shows the time-dependent changes in the switching control signal, the state of the reverse connection protection relay, the operation permission signal, and the operating state of the control device. In the illustrated example, the voltage of the switching control signal supplied from the power switch 9 is initially high. When no open circuit fault occurs, both ends of the reverse connection protection relay 2 are in a conductive state (ON). Therefore, current flowing from the positive terminal to the negative terminal of the power supply 8 passes through the switching element 2s. When an open circuit fault occurs, the connection between both ends of the reverse connection protection relay 2 is interrupted (OFF). Therefore, current flowing from the positive terminal to the negative terminal of the power supply 8 passes through the rectifier element 14 connected in parallel with the switching element 2s. Therefore, the potential difference generated across both ends of the reverse connection protection relay 2 differs depending on whether the current passes through the switching element 2s or the rectifier element 14.

[0035] As an example, assume that the drain-source resistance of the MOSFET serving as the switching element 2s is 1 mΩ, the forward voltage Vf of the parasitic diode serving 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 the forward voltage of the parasitic diode, 700 mV. The forward voltage depends on the characteristics of each rectifying element 14, but is a value that is sufficiently larger than the potential difference when the current passes through the switching element 2s. A reference potential can be set so that the voltage detection unit 3 can detect a voltage equivalent to this potential difference.

[0036] 1 , the reference potential GND of the voltage detection unit 3 is set to be equal to the potential of the negative pole 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 polarity protection relay 2 and the motor drive circuit 5. The position where the reference potential GND is set and the position where the reference potential GND_PCB is set are separated across both ends of the reverse polarity protection relay 2.

[0037] As described above, the potential difference between the reference potential GND and the reference potential GND_PCB significantly differs between when an open circuit fault occurs in the reverse connection protection relay 2 and when no open circuit fault occurs. Therefore, the control device 4 determines whether an open circuit fault has occurred in the switching element 2s based on the detected voltage signal input from the voltage detection unit 3. The voltage relative to the reference potential GND_PCB is the potential difference between both ends of the reverse connection protection relay 2. More specifically, the control device 4 compares the voltage indicated by the detected voltage signal with a preset open circuit fault threshold and determines whether or not an open circuit fault has occurred based on whether or not the voltage indicated by the detected voltage signal is higher than the open circuit fault threshold. The open circuit fault threshold may be set between the voltage (potential difference) detected when an open circuit fault occurs and the voltage (potential difference) detected when no open circuit fault occurs.

[0038] When the motor 7 is driven with an open circuit fault occurring in the reverse connection protection relay 2, the drive current passes through the rectifier element 14. The power consumption of the rectifier element 14 is equal to the product of the potential difference across the rectifier element 14 and the drive current. This power consumption is greater than the power consumption of the switching element 2s when the drive current passes through the switching element 2s. The increased heat generation can lead to abnormal heat generation, which can cause malfunction, smoke, or fire. Therefore, the control device 4 may determine whether or not an open circuit fault has occurred in the reverse connection protection relay 2 before starting operation of the motor drive circuit 5. When determining the occurrence of an open circuit fault, the control device 4 does not need to 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 heat generation due to current flowing through the rectifier element 14 can be avoided.

[0039] Next, a specific example of a method for detecting a short-circuit fault in the reverse connection protection relay 2 will be described. A short-circuit fault in the reverse connection protection relay 2 refers to a fault in which the switching element 2s is conductive (ON) when it should be interrupted (OFF). In the following explanation, it is assumed that the voltage of the switching control signal from the power switch 9 changes from High to Low at time T0, as illustrated in FIG. 3. At this time, the voltage of the operation permission signal output from the power output holding circuit 6 remains High. Therefore, even after time T0 has passed, the operation of the control device 4 continues. The control device 4 stops the operation of the motor drive circuit 5 and performs a shutdown process for its own device. Thereafter, at time T1, the control device 4 stops its operation. At this time, the voltage of the operation permission signal output from the power output holding circuit 6 changes from High to Low. The control device 4 can secure an opportunity to perform fault detection for the reverse connection protection relay 2 during the output holding period from time T0 to time T1.

[0040] During the output holding period, the voltage of the control signal is low, so unless a short circuit fault has occurred, both ends of the switching element 2s should be in a cut-off state (OFF). Therefore, the current flowing from the positive terminal to the negative terminal of the power supply 8 passes through the rectifier element 14. On the other hand, if a short circuit fault has occurred, the current flowing from the positive terminal to the negative terminal of the power supply 8 passes through the switching element 2s. Thus, the potential difference across the reverse connection protection relay 2 differs depending on whether the current passes through the rectifier element 14 or the switching element 2s.

[0041] As an example, assume that the drain-source resistance of the MOSFET serving as the switching element 2s is 1 mΩ, the forward voltage Vf of the parasitic diode serving 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 corresponds to the forward voltage of the parasitic diode, 700 mV.

[0042] Therefore, the control device 4 determines whether or not a short circuit fault has occurred in the switching element 2s based on the detected voltage signal input from the voltage detection unit 3. The detected voltage signal indicates the voltage detected by the voltage detection unit 3. More specifically, the control device 4 compares the voltage indicated by the detected voltage signal with a preset short circuit fault threshold and determines whether or not a short circuit fault has occurred based on whether or not the voltage indicated by the detected voltage signal is lower than the short circuit fault threshold. The short circuit fault threshold may be set to a value between the voltage (potential difference) detected when a short circuit fault has occurred and the voltage (potential difference) detected when a short circuit fault has not occurred. As described above, the reference potential GND of the voltage detection unit 3 may be 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. With this setting, the voltage indicated by the detected voltage signal corresponds to the potential difference between both ends of the reverse connection protection relay 2.

[0043] When a short circuit fault is determined, the control device 4 supplies DC power to a warning lamp provided in the vehicle, for example, as a notification signal for notifying the driver of the short circuit fault. The warning lamp lights up in response to the DC power from the control device 4. A driver who sees the illuminated warning lamp is notified of the occurrence of a short circuit fault. When an ignition switch is used as an example of the power switch 9, current protection is achieved by connecting a battery as the power source 8 during the ignition OFF period. The ignition OFF period corresponds to the period during which an ignition signal with a high voltage is not input. Generally, battery replacement is not performed while the vehicle is running. Therefore, it may be sufficient for practical purposes to perform short circuit fault detection during the ignition OFF period.

[0044] In the above explanation, an example has been given in which the reverse polarity protection relay 2 is driven based on a switching control signal from the power switch 9 instead of power supplied from the power supply 8, and the operating voltage of the control device 4 is maintained using the power output holding circuit 6. When power is not supplied from the power supply 8, even if the conduction between both ends of the reverse polarity protection relay is cut off using a switching control signal, the operating 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 detect a short circuit fault in the reverse polarity protection relay 2.

[0045] <Second embodiment> A second embodiment will be described with reference to the drawings. The following description will focus mainly on the differences from the first embodiment. Unless otherwise specified, the description of the first embodiment will be used for other matters. The electronic control device 1 according to this embodiment can detect the presence or absence of a short circuit fault as the state of the reverse connection protection relay 2 not only when the power supply from the power source 8 is cut off but also when the power supply from the power source 8 is started. Thereafter, the opening and closing of the reverse connection protection relay 2 is controlled based on the switching control signal.

[0046] FIG. 4 is a circuit diagram showing an example of the configuration of the electronic control device 1 according to this embodiment. The electronic control device 1 according to this 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 supply circuit 10, as well as 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 is connected to them. When a switching control signal indicating a need for power supply is input from the power switch 9 and a switching command signal indicating a switching command to the reverse connection protection relay 2 is input from the control device 4, the reverse connection protection relay drive control circuit 24 outputs a switching control signal indicating a need for power supply to the reverse connection protection relay 2. When a switching control signal indicating a need for power supply is input from the power switch 9 or when a switching command signal indicating a switching command for 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 switching control signal indicating a need for power supply to the reverse connection protection relay 2. Whether a switching command is required is indicated, for example, by whether the voltage of the switching command signal is High or Low.

[0047] Therefore, when a switching command is received from the control device 4, the reverse connection protection relay drive control circuit 24 can control the opening and closing of the reverse connection protection relay 2 in accordance with the switching control signal from the power switch 9. When a switching command is not received, the reverse connection protection relay drive control circuit 24 cuts off both ends of the reverse connection protection relay 2 regardless of whether a switching control signal with a high voltage is input. In this state, the control device 4 can determine whether a short circuit fault has occurred in the reverse connection protection relay 2 based on the voltage indicated by the detected power signal input from the voltage detection unit 3. After determining whether a short circuit fault has occurred, the control device 4 outputs a switching command signal indicating a switching command for the reverse connection protection relay 2 to the reverse connection protection relay drive control circuit 24. The switching command is represented, for example, by the voltage of the switching command signal being high. The control device 4 is equipped with, for example, a general-purpose input / output (GPIO) port and can output the switching command signal using the GPIO.

[0048] The control device 4 executes an initialization process when power supply from the power supply circuit 10 starts. The initialization process includes, for example, reading internal data stored in memory and detecting various devices connected to the control device. After completing the initialization process, the control device 4 can determine whether a short circuit fault has occurred. After determining that there is no short circuit fault, the control device 4 outputs a switching command signal to the reverse connection protection relay drive control circuit 24. This enables the control device 4 to control the opening and closing of the reverse connection protection relay 2 based on the switching control signal from the power switch 9. At this stage, the control device 4 may 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 in the reverse connection protection relay 2 will be described. FIG. 5 is an explanatory diagram for explaining an example of a method for detecting a short circuit fault in the reverse connection protection relay 2 according to this embodiment. In the following description, it is assumed that initially, power is not supplied from the power source 8 to the power supply circuit 10 via the power switch 9, and both the control device 4 and the motor drive circuit 5 are not operating. FIG. 5 shows the time changes of the switching control signal, the power supply circuit output, the operating state of the control device 4, the switching command, and the state of the reverse connection protection relay 2. In the illustrated example, the voltage of the switching control signal supplied from the power switch 9 is initially low. If no short circuit fault has occurred, the reverse connection protection relay 2 is in an OFF state, where continuity between both ends is interrupted. In this state, power is not supplied from the power source 8 to the power supply circuit 10 via the power switch 9. Therefore, the voltage of the power supplied from the power supply circuit 10 to the control device 4 is 0 V (OFF). At this point, the control device 4 is not operating (OFF), and therefore no switching command signal is output from the control device 4 (OFF).

[0050] Next, assume that the voltage of the switching control signal from the power switch 9 changes from low to high at time T0. At this time, the voltage of the power supplied from the power supply circuit 10 to the control device 4 begins to rise from 0 V (OFF) and reaches a predetermined operating voltage (ON) of the control device 4 at time T1. At this point, the voltage stabilizes, and the initialization process (ON) begins as the operation of the control device 4. After the initialization process is completed, at time T2, the control device 4 starts outputting a switching command signal indicating a switching command to the reverse connection protection relay drive control circuit 24 (ON). At this time, the reverse connection protection relay drive control circuit 24 starts outputting a switching control signal with a high voltage to the reverse connection protection relay 2. If no short circuit fault has occurred, both ends of the reverse connection protection relay 2 begin to change from a blocked state (OFF) to a conducting state (ON). Therefore, during the period from the end of the initialization process until the output of the switching command signal at time T2, the control device 4 can determine whether or not a short circuit fault has occurred in the reverse connection protection relay 2 based on the voltage value indicated by the detected power signal input from the voltage detection unit 3.

[0051] During this period, the power supply circuit 10 and the control device 4 operate, causing a current to flow from the positive terminal of the power supply 8 to the negative terminal. If no short-circuit fault occurs in the reverse polarity protection relay 2, both ends of the switching element 2s should be in a blocked state (OFF). In this state, the generated current passes through the rectifier element 14, which is connected in parallel with the switching element 2s. If a short-circuit fault occurs, both ends of the switching element 2s are in a conductive state (ON). Therefore, the current flowing from the positive terminal to the negative terminal of the power supply 8 passes through the switching element 2s. Therefore, the potential difference generated across the reverse polarity protection relay 2 differs depending on whether the current passes through the rectifier element 14 or the switching element 2s.

[0052] As an example, assume that the drain-source resistance of the MOSFET serving as the switching element 2s is 1 mΩ, the forward voltage Vf of the parasitic diode serving 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 of 700 mV. When the current passes through the MOSFET, the potential difference is 1 mV.

[0053] Therefore, the control device 4 determines whether or not a short circuit has occurred in the switching element 2s based on the detected voltage signal input from the voltage detection unit 3. More specifically, the control device 4 compares the voltage indicated by the detected voltage signal with a preset short circuit threshold, and determines whether or not a short circuit has occurred based on whether or not the voltage indicated by the detected voltage signal is lower than the short circuit threshold. The short circuit threshold may be set to a value between the voltage when a short circuit has occurred and the voltage when a short circuit has not occurred.

[0054] Therefore, the reverse connection protection relay drive control circuit 24 controls the reverse connection protection relay 2 so that its conduction is interrupted even when power is supplied from the power source 8. Therefore, the control device 4 can determine whether or not a short circuit fault has occurred in the reverse connection protection relay 2 even after the control device 4 has consumed power supplied from the power source 8 and started operating.

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

[0056] The power source 8 is not limited to a portable power source such as a battery, but may also be a stationary power source. Power supply from the power source 8 to the electronic control device 1 is not limited to being wired, but may also be wireless. If a wireless charger is used as the power source 8, the electronic control device 1 may be equipped with a wireless power receiver and receive power transmitted from the wireless charger. The load is not limited to the motor drive circuit 5, but may be any other device that consumes power supplied from the power source 8. The device that serves as the load does not necessarily have to be configured integrally with the electronic control device 1.

[0057] The switching element 2s is not necessarily limited to a MOSFET, but may be another type of bipolar transistor. The rectifying element 14 is not necessarily limited to a diode, but may be a selenium rectifier, or the like. A display may be used as the notification unit 16. The control device 4 may generate a signal representing information indicating the determined state in the form of characters, symbols, or images as the notification signal and output it to the display. If a speaker is used as the notification unit 16, a signal representing information indicating the determined state in the form of sound may be generated as the signal and output to the speaker. The notified information may include information indicating measures to be taken in response to the state (e.g., replacing parts, contacting a dealer, etc.) in addition to the information indicating the determined state.

[0058] As described above, the electronic control device 1 according to the present disclosure includes the reverse connection protection relay 2, the voltage detection unit 3, and the control device 4. The reverse connection protection relay 2 includes a switching element 2s and a rectifying element 14, which are connected in parallel. The negative electrode of the rectifying element 14 and the positive electrode of the rectifying element 14 are connected to the negative electrode of the power source 8 and a load (for example, the electric motor drive circuit 5), respectively. The load consumes the power supplied from the power source 8. The opening and closing of the switching element 2s is controlled based on a switching control signal that indicates whether or not power is being supplied from the power source. The voltage detection unit 3 detects the potential difference across 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 electrical resistance of the reverse connection protection relay 2 depends on its state. With this configuration, the state of the reverse connection protection relay 2 is determined based on the potential difference generated across the reverse connection protection relay 2 due to the current flowing through the reverse connection protection relay 2 in response to the power supply from the power source 8. Therefore, the state of the reverse connection protection relay 2 can be detected autonomously without increasing the circuit size or cost.

[0059] When power is supplied from the power source 8, 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. According to this configuration, when the reverse connection protection relay 2 is instructed to be conductive, it is possible to determine whether or not an open fault has occurred 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 convert the power supply voltage of the power supplied from the power supply 8 into an 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 cause the power supply circuit 10 to hold the operating voltage. The control device 4 may detect the presence or absence of a short circuit fault as the state of the reverse polarity protection relay 2. With this configuration, even if the power supply from the power source 8 is cut off, the operating voltage of the control device 4 is maintained. On the other hand, the reverse polarity protection relay 2 is controlled to be cut off from conduction. The control device 4 can determine whether or not a short circuit fault has occurred based on the potential difference between both ends of the reverse polarity protection relay 2 without stopping its operation.

[0061] The electronic control device 1 may further include a drive control circuit (for example, a reverse connection protection relay drive control circuit 24). The drive control circuit may turn on the switching element 2s when power is supplied from the power source 8 and a switching command is acquired from the control device 4. The control device 4 may 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 source 8 and a switching command is acquired from the control device 4. According to this configuration, even if power is supplied from the power source 8, the conduction of the switching element 2s is interrupted until a switching command is received from the control device 4. Even before a switching command is input, the control device 4 operates due to the power supply from the power source 8, and it is possible to determine whether or not a short circuit fault has occurred based on the potential difference across the reverse connection protection relay 2.

[0062] The reference potential that is the reference for 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 a potential difference across 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, one MOSFET is configured as the reverse polarity protection relay 2. Reducing the number of parts contributes to downsizing and cost reduction of the electronic control device 1.

[0064] The load may be an electric motor drive circuit 5 that drives an electric motor 7. The opening and closing 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 configuration, the opening and closing of the switching element 2s is linked to the power supply to the motor drive circuit 5 by the ignition switch, making it possible to prevent a reverse current flow to the motor drive circuit 5 due to reverse connection of the power supply 8. Furthermore, by using an ignition signal to control the switching 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. Addition, omission, substitution, and other modifications of the configuration are possible within the scope of the gist of the present disclosure. The direction of arrows shown in block diagrams and other drawings is for convenience of explanation and does not limit the direction of flow of information, data, signals, etc. during implementation. Furthermore, the present disclosure is not limited by the foregoing description, but only by the appended claims. [Industrial Applicability]

[0066] According to the electronic control device and electronic control method disclosed herein, the state of the reverse connection protection relay 2 is determined based on the potential difference generated across the reverse connection protection relay 2 due to the current flowing through the reverse connection protection relay 2 in response to the power supply from the power source 8. Therefore, the state of the reverse connection protection relay 2 is detected autonomously without increasing the circuit size or cost. [Explanation of symbols]

[0067] 1...electronic control device, 2...reverse polarity 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...resistance element, 13...zener diode, 14...rectifier element, 24...reverse polarity protection relay drive control circuit

Claims

1. A reverse connection protection relay, a voltage detection unit, a control device, a power supply circuit, and a power output holding circuit. An electronic control device comprising: The reverse connection protection relay includes a switching element and a rectifying element, the switching element and the rectifying element are connected in parallel, a negative electrode of the rectifying element and a positive electrode of the rectifying element are connected to a negative electrode of a power source and a load, respectively; the load consumes the power supplied from the power source; The switching element is controlled to be open or closed based on a switching control signal indicating whether or not power is being supplied from the power source, the power supply circuit converts a power supply voltage of the 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 supply output holding circuit causes the power supply circuit to hold the operating voltage; The voltage detection unit detects a potential difference between both ends of the reverse connection protection relay, The control device detects the presence or absence of a short circuit fault as the state of the reverse connection protection relay based on the potential difference. Electronic control unit.

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

3. Further comprising a drive control circuit, the drive control circuit turns on the switching element when power is supplied from the power source and a switching command 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. The electronic control device according to claim 1 .

4. The reference potential that is the reference for the operating voltage of the control device and the reference potential of the voltage detection unit are separated across both ends of the reverse connection protection relay. The electronic control device according to claim 1 .

5. 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. The electronic control device according to claim 1 .

6. the load is an electric motor drive circuit that drives an electric 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. The electronic control device according to claim 1 .

7. A reverse connection protection relay, a voltage detection unit, a control device, a power supply circuit, and a power output holding circuit. An electronic control device comprising: 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 a power source and the positive electrode of the rectifying element, respectively; The load consumes power supplied from a power supply, The switching element is controlled to be open or closed based on a switching control signal indicating whether or not power is being supplied from the power source, An electronic control method for an electronic control device, in which the power supply circuit converts a power supply voltage of the 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 supply output holding circuit causes the power supply circuit to hold the operating voltage; a first step in which the voltage detection unit detects a potential difference between both ends of the reverse connection protection relay; a second step in which the control device detects the presence or absence of a short circuit fault as the state of the reverse connection protection relay based on the potential difference. Electronic control method.

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