Relay diagnosis device and relay diagnosis method

Abstract

To provide a relay diagnosis device capable of diagnosing a connection state of a relay switch.SOLUTION: A relay diagnosis device 10 for diagnosing a connection state of a relay switch 2 connected between a power source 1 and a load 4 includes: a pulse transformer 11 having a primary coil 11a and a secondary coil 11b and connecting the secondary coil 11b in parallel with the relay switch 2; and a controller 14 for inputting a pulse signal to the primary coil 11a and diagnosing the connection state of the relay switch 2 on the basis of an output signal output from the primary coil 11a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a relay diagnostic device and a relay diagnostic method. [Background technology]

[0002] For example, the vehicle power supply system described in Patent Document 1 includes an alternator, a lead storage battery and a lithium ion storage battery, a MOS switch that connects and disconnects these two batteries, and an ECU; during non-regenerative power generation, the ECU switches the MOS switch to a disconnected state to supply power from the lithium ion storage battery to an electrical load, and during regenerative power generation, the ECU switches the MOS switch to a conductive state to charge the battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-038146 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above power supply system is configured on the assumption that the MOS switch operates normally, and does not diagnose the state of the MOS switch.

[0005] An object of the present invention is to provide a relay diagnostic device and a relay diagnostic method capable of diagnosing the connection state of a relay switch connected between a power source and a load. [Means for solving the problem]

[0006] The present invention solves the above problem by inputting a pulse signal to a primary coil included in a pulse transformer connected in parallel with a relay switch, and diagnosing the connection state of the relay switch based on the output signal output from the primary coil. Effect of the Invention

[0007] The present invention can diagnose the connection state of a relay switch. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a power supply system including a relay diagnostic device according to the present embodiment. [Diagram 2] FIG. 2 is a table showing the correlation between the connection state of the relay switch, the impedance of the relay switch, the impedance on the vehicle side, and the output signal. [Diagram 3] FIG. 3 is a table showing the characteristics of an input signal (pulse signal) and the characteristics of an output signal (pulse output). [Figure 4] FIG. 4 is a flowchart showing a control flow of a method for diagnosing a relay switch, which is executed by a processor included in the controller. [Diagram 5] FIG. 5 is a block diagram of a power supply system including a relay diagnostic device according to a modified example of this embodiment. [Figure 6] FIG. 6 is a block diagram of a power supply system including a relay diagnostic device according to a modified example of this embodiment. [Figure 7] FIG. 7 is a table showing the characteristics of an input signal (pulse signal) and the characteristics of an output signal (pulse output). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of a relay diagnostic device and a relay diagnostic method according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a power supply system including a relay diagnostic device including an embodiment of the present invention. The relay diagnostic device diagnoses the connection state of a relay switch 2 connected between a power supply 1 and a load 4. The power supply system includes a power supply 1, a relay switch 2, a battery 3, a load 4, and a relay diagnostic device 10. The power supply system is, for example, a system mounted on a vehicle. Note that in the following description, the embodiment will be described taking an example in which the power supply system is mounted on a vehicle, but the power supply system may be mounted on a device other than a vehicle.

[0010] Power supply 1 is a power supply for a vehicle, and is made up of a stack of multiple secondary batteries such as lithium-ion batteries, and supplies power to load 4. Power supply 1 is a high-voltage battery, and can be charged by a charging device external to the vehicle. Power supply 1 can also be charged by regeneration of a motor included in load 4 while the vehicle is running. One end of power supply 1 is connected to relay switch 2 via a power line, and the other end of power supply 1 is grounded.

[0011] The relay switch 2 is a switch that switches between electrical continuity and interruption between the power source 1 and the load 4, or between the power source 1 and the battery 3. The relay switch 2 is a switch that controls the current input to or output from the power source 1, the battery 3, and the load 4, and is provided to protect the power source 1, the battery 3, and the load 4. The relay switch 2 is connected to a power supply line that connects between the power source 1 and the battery 3 and between the power source 1 and the load 4. The relay switch 2 switches on and off in response to a control command from a vehicle controller. When the relay switch 2 is turned on, electrical continuity is established between the power source 1 and the battery 3, and the battery 3 can be charged with the power of the power source 1. When the relay switch 2 is turned on, electrical continuity is established between the power source 1 and the load 4, and the power of the power source 1 can be supplied to the load 4. The relay switch 2 may be a switch built into a battery pack including the power source 1.

[0012] The battery 3 is an auxiliary battery and supplies power to the auxiliary devices included in the load 4. The battery 3 has a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery, and can be charged by the power of the power source 1. The load 4 is a circuit or device that consumes the power of the power source 1 or the battery 3. The load 4 is an auxiliary device such as a display or a meter, a vehicle motor, an air conditioner, or other in-vehicle device. One end of the battery 3 and one end of the load 4 are connected to the power source 1 via a relay switch 2, and the other end of the battery 3 and the other end of the load 4 are grounded.

[0013] The relay diagnostic device 10 includes a pulse transformer 11, an input line 12, an output line 13, and a controller 14. The pulse transformer 11 is an insulating transformer and has a primary coil 11a and a secondary coil 11b. The secondary coil 11b is connected in parallel with the relay switch 2. In other words, both ends of the secondary coil 11b are connected to both ends of the relay switch 2. One end of the primary coil 11a is connected to the input line 12 and the output line 13, and the other end of the primary coil 11a is grounded.

[0014] The input line 12 is a wiring that inputs an input signal (pulse signal) to the primary coil in response to a command from the controller 14. The input line 12 connects between an oscillator that generates a pulse signal and the primary coil 11a. A resistor is connected to the input line 12. The output line 13 is a wiring that outputs an output signal that is output from the primary coil 11a in response to the input of a pulse signal to the controller 14. One end of the output line 13 is connected to one end of the primary coil 11a, and the other end of the output line 13 is connected to the controller 14.

[0015] The controller 14 inputs a pulse signal to the primary coil 11a and diagnoses the connection state of the relay switch based on the output signal output from the primary coil 11a. When a pulse signal is input to the primary coil 11a, the pulse signal flows from the secondary side of the pulse transformer 11 to the relay switch 2. The magnitude of the secondary current flowing through the secondary coil 11b and the relay switch 2 varies depending on the impedance of the relay switch 2. When the relay switch 2 is in a closed state, the impedance of the relay switch 2 is zero, and when the relay switch 2 is in an open state (off state), the impedance of the relay switch 2 is infinite. The change in impedance of the relay switch 2 is reflected in a change in the output signal (output pulse) of the primary side current, so the connection state of the relay switch (open state, closed state) can be determined from the peak value of the output signal.

[0016] The controller 14 inputs a pulse signal to the primary coil 11a from the input line 12. When the relay switch 2 is in a closed state, the impedance on the primary side of the pulse transformer 11 is small, and the peak value of the output signal output from the primary coil 11a to the output line 13 is low. On the other hand, when the relay switch 2 is in an open state, the impedance on the primary side of the pulse transformer 11 is large, and the peak value of the output signal output from the primary coil 11a to the output line 13 is high.

[0017] The controller 14 diagnoses the connection state of the relay switch 2 by detecting an output signal (peak value) that changes according to the connection state of the relay switch 2. Specifically, the controller 14 outputs a pulse signal to the primary coil 11а and detects the peak value of the output signal output to the output line 13. The peak value of the output signal corresponds to the divided voltage of the resistor connected to the input line and the primary coil 11а. The controller 14 compares the detected peak value with a peak threshold value, and diagnoses the connection state of the relay switch 2 according to the comparison result. The peak threshold value is a preset threshold value. When the detected peak value is equal to or greater than the peak threshold value, the controller 14 determines that the relay switch 2 is in an open state. On the other hand, when the detected peak value is less than the peak threshold value, the controller 14 determines that the relay switch 2 is in a closed state. That is, when the peak value of the output signal is high, the controller 14 determines that the relay switch 2 is in an open state, and when the peak value of the output signal is low, the controller 14 determines that the relay switch 2 is in a closed state.

[0018] The controller 14 may detect the primary impedance of the pulse transformer 11 from the peak value of the output signal, and diagnose the connection state of the relay switch 2 based on the change in the primary impedance. When the relay switch 2 is in a closed state, the secondary impedance of the pulse transformer 11 becomes zero, and the primary impedance of the pulse transformer 11 becomes small. On the other hand, when the relay switch 2 is in an open state, the pulse signal does not flow from the secondary side of the pulse transformer 11 to the relay switch 2, but flows from the power source 1 to the circuit that conducts the battery 3 and the load 4 via the secondary coil 11b, so that the secondary impedance of the pulse transformer 11 becomes equal to the impedance of the vehicle-side system including the battery 3 and the load 4, and the primary impedance of the pulse transformer 11 becomes large. When the peak value of the output signal is low, the controller 14 may detect that the primary impedance of the pulse transformer is small and determine that the relay switch 2 is in a closed state. On the other hand, when the peak value of the output signal is high, the controller 14 may detect that the primary impedance of the pulse transformer is large and determine that the relay switch 2 is in an open state.

[0019] FIG. 2 is a table showing the correlation between the connection state of the relay switch 2, the impedance of the relay switch 2 (relay impedance), the vehicle-side impedance, and the output signal. The vehicle-side impedance indicates the impedance of the vehicle system including the battery 3 and the load 4. The vehicle-side impedance changes depending on the state of the ignition switch that switches the vehicle system on and off (the startup state of the vehicle system). When the ignition switch is on, power is supplied to the load 4 and the load 4 is in an operable state, so the vehicle-side impedance (Z) is small. On the other hand, when the ignition switch is off, power is not supplied to the load 4 and the load 4 is in an electrically cut-off state, so the vehicle-side impedance (Z) is large. When the vehicle is an electric vehicle, the ignition switch corresponds to the main switch.

[0020] 2, when the connection state of the relay is "closed", the impedance of the relay switch 2 is zero. When a pulse signal is output to the primary coil 11a, the current flowing through the secondary coil 11b flows within a parallel circuit (closed circuit) between the secondary coil 11b and the on-state relay switch 2, so the impedance on the vehicle side does not affect the conduction of current on the secondary side of the pulse transformer 11. And the peak value of the output signal flowing through the output line 13 is almost zero.

[0021] When the connection state of the relay is "open", the impedance of the relay switch 2 is infinite. When a pulse signal is output to the primary coil 11a, the current flowing through the secondary coil 11b does not flow through the relay switch 2, but flows from the power source 1 to a circuit that conducts the battery 3 and the load 4 via the secondary coil 11b. When the ignition switch is on, the vehicle side impedance is small, and the peak value of the output signal flowing through the output line 13 is small. When the ignition switch is off, the vehicle side impedance is large, and the peak value of the output signal flowing through the output line 13 is large.

[0022] FIG. 3 is a table showing the characteristics of the input signal (pulse signal) and the characteristics of the output signal (pulse output). In FIG. 3, "Close" indicates the "closed state" of the relay switch, "Open Vehicle Z Small" indicates the "open state" of the relay switch and the state where the impedance on the vehicle side is small, and "Open Vehicle Z Large" indicates the state where the relay switch is "open state" and the impedance on the vehicle side is large. When the relay switch 2 is in the closed state, the peak value of the output signal is almost zero. When the relay switch 2 is in the open state and the impedance on the vehicle side is small, the peak value of the output signal is small (however, it is higher than the peak value when the relay switch 2 is in the closed state). When the relay switch 2 is in the open state and the impedance on the vehicle side is high, the peak value of the output signal is high.

[0023] As shown in Fig. 3, the peak value of the output signal changes depending on the activation state of the vehicle system (on / off state of the ignition switch). Therefore, the controller 14 may diagnose the activation state of the vehicle system including the load 4 according to the height of the peak value of the output signal. As described above, the controller 14 determines that the relay switch 2 is in an open state when the detected peak value is equal to or greater than the peak value threshold. Furthermore, when the peak value is high, the controller 14 determines that the vehicle system is not activated (ignition switch is off), and when the peak value is low, the controller 14 determines that the vehicle system is activated (ignition switch is on).

[0024] In addition, when the vehicle system is activated, the vehicle-side impedance of the controller 14 changes depending on the device that is actually being driven among the on-board devices included in the load 4. If it is difficult to detect the peak value of the output signal due to the change in the vehicle-side impedance, the AD resolution may be changed. When the ignition switch is on, the controller 14 increases the resolution for detecting the output signal, and when the ignition switch is off, the resolution for detecting the output signal is reduced. As shown in FIG. 3, when the relay switch 2 is in an open state and the ignition switch is on, the peak value of the output signal is reduced. At this time, the controller 14 increases the resolution, so that a low peak value can be detected. On the other hand, when the relay switch 2 is in an open state and the ignition switch is off, the peak value of the output signal is increased. At this time, even if the controller 14 reduces the resolution, the controller 14 can detect a high peak value. The controller 14 reduces the resolution in accordance with the timing of detecting a low peak value, so that the power consumption of the controller 14 can be reduced.

[0025] 4, a method for diagnosing the relay switch 2, which is executed by a processor included in the controller 14, will be described. The controller 14 executes the following control flow when the controller 14 is started up and / or at a predetermined interval after the controller 14 is started up.

[0026] In step S1, the controller 14 receives a signal indicating the on / off state of the ignition switch from a vehicle controller that controls the on / off of the ignition switch, and determines whether the ignition switch is on. If the ignition switch is on, the controller resolution is increased in step S2. On the other hand, if the ignition switch is off, the controller resolution is decreased in step S3.

[0027] In step S4, the controller 14 inputs a pulse signal from the input line 12 to the primary coil 11a. In step S5, the controller 14 detects the output signal (peak value) output from the primary coil 11a to the output line 13. In step S6, the controller 14 determines whether the detected peak value is equal to or greater than the peak threshold. If the peak value is equal to or greater than the peak threshold, the controller 14 determines that the relay switch 2 is in an open state (relay switch 2 is in an off state) (step S7). If the peak value is less than the peak threshold, the controller 14 determines that the relay switch 2 is in a closed state (relay switch 2 is in an on state) (step S8).

[0028] Then, the controller 14 ends the flow of estimating the charging rate shown in FIG.

[0029] As described above, the relay diagnostic device and relay diagnostic method according to this embodiment input a pulse signal to the primary coil 11a included in the pulse transformer 11 connected in parallel with the relay switch 2, and diagnose the connection state of the relay switch 2 based on the output signal output from the primary coil 11a. In this way, the connection state of the relay switch 2 connected between the power source 1 and the load 4 can be diagnosed.

[0030] In a reference example different from the present invention, the voltage at both terminals of the relay switch 2 and the relay current flowing through the relay switch 2 are detected, and the state of the relay switch 2 is diagnosed based on a combination of the detected voltage and the detected current. When the voltage at both terminals of the relay switch 2 is zero (the potential difference between the voltage at the high potential terminal and the voltage at the low potential terminal of the relay switch 2 is zero) and the relay current is higher than zero, the relay switch 2 is determined to be in a closed state. When the voltage at both terminals of the relay switch 2 is higher than zero (the potential difference between the voltage at the high potential terminal and the voltage at the low potential terminal of the relay switch 2 is not zero) and the relay current is zero, the relay switch 2 is determined to be in an open state. However, in the method of the reference example, the voltage at the high potential terminal and the voltage at the low potential terminal of the relay switch 2 may become the same voltage depending on the output voltage of the power source 1 and the input voltages to the battery 3 and the load 4. In this case, even if the relay switch 2 is turned on, no relay current flows, and therefore the method of the reference example cannot determine the closed state of the relay.

[0031] The relay diagnostic device and relay diagnostic method according to the present embodiment can diagnose the connection state of the relay switch 2 from a change in impedance of the relay switch 2 without being affected by environmental conditions such as the voltage of the power source 1 and the relay current.

[0032] In this embodiment, the controller 14 detects the primary impedance of the pulse transformer 11 based on the output signal, and diagnoses the connection state of the relay switch 2 based on the amount of change in the primary impedance. This makes it possible to diagnose the connection state of the relay switch 2 from the change in the impedance of the relay switch 2.

[0033] In this embodiment, the controller 14 determines that the relay switch 2 is in an open state when the peak value of the output signal is high, and determines that the relay switch 2 is in a closed state when the peak value of the output signal is low. This makes it possible to diagnose the connection state of the relay switch 2.

[0034] In this embodiment, the controller 14 diagnoses the start-up state of the system including the load 4 according to the height of the peak value of the output signal. This makes it possible to diagnose the start-up state of the system including the load 4 from the change in impedance on the secondary side of the pulse transformer.

[0035] In this embodiment, the controller 14 increases the resolution for detecting the output signal when the ignition switch is on, and decreases the resolution for detecting the output signal when the ignition switch is off. This makes it possible to diagnose the connection state of the relay switch 2 even if the impedance of the system including the load 4 changes while the relay switch 2 is in an open state.

[0036] As a modification of this embodiment, as shown in FIG. 5, a capacitor 15 may be connected between the relay switch 2 and the secondary coil 11b. FIG. 5 is a block diagram of a power supply system including a relay diagnostic device according to a modification of this embodiment. The relay diagnostic device 10 includes a capacitor 15 in addition to the pulse transformer 11 and the like. The capacitor 15 is connected between the low potential side terminal of the relay switch 2 and the low potential side terminal of the secondary coil 11b. The capacitor 15 is a coupling capacitor that cuts off the DC component. Both ends of the relay switch 2 are connected by the secondary coil 11b. Therefore, when the relay switch 2 is in an open state, there is a possibility that leakage current will flow from the power supply 1 through the secondary coil 11b to the battery 3 or the load 4. In the modification, the capacitor 15 is connected to cut off the DC component of the leakage current and to pass a pulse signal. This makes it possible to cut off the leakage current. The capacitor 15 is connected between the high potential side terminal of the relay switch 2 and the high potential side terminal of the secondary coil 11b.

[0037] As a modification of this embodiment, as shown in FIG. 6, the relay switch 2 may be a circuit in which a semiconductor switch 21 and a semiconductor switch 22 are connected in series. FIG. 6 is a block diagram of a power supply system equipped with a relay diagnostic device according to a modification of this embodiment. The relay switch 2 has a semiconductor switch 21 and a semiconductor switch 22 connected in series. The semiconductor switches 21 and 22 are transistor switches such as MOSFETs. The semiconductor switch 21 is a discharge side switch, and the semiconductor switch 22 is a charge side switch. The forward direction of the parasitic diode included in the semiconductor switch 21 is opposite to the conduction direction of the current flowing from the power supply 1 to the load 4. The forward direction of the parasitic diode included in the semiconductor switch 22 is the same as the conduction direction of the current flowing from the power supply 1 to the load 4. That is, the semiconductor switch 21 and the semiconductor switch 22 are connected in series with the conduction directions of the parasitic diodes opposite to each other.

[0038] The controller 14 diagnoses the connection states of the semiconductor switches 21 and 22 according to the height of the peak value of the output signal. Fig. 7 is a table showing the characteristics of the input signal (pulse signal) and the characteristics of the output signal (pulse output). In Fig. 7, "Close / Close" indicates the "closed state" of the semiconductor switch 21 and the "closed state" of the semiconductor switch 22, "Close / Open" indicates the "closed state" of the semiconductor switch 21 and the "open state" of the semiconductor switch 22, and "Open / Open" indicates the "open state" of the semiconductor switch 21 and the "open state" of the semiconductor switch 22.

[0039] Since the pulse signal flowing from the secondary coil 11b to the semiconductor switches 21 and 22 is an AC signal (pulse current), the direction of the pulse current flow differs depending on whether the semiconductor switch 21 or the semiconductor switch 22 is in an open state. For example, when the semiconductor switch 21 is in a closed state and the semiconductor switch 22 is in an open state, the pulse current flows in the direction of the arrow a shown in FIG. 6, but does not flow in the direction of the arrow b. In other words, the pulse current corresponding to the negative of the input signal (pulse signal) flows to the relay switch 2, and the pulse current corresponding to the positive of the input signal (pulse signal) does not flow to the relay switch 2. Therefore, as shown in "Close / Open" in FIG. 7, the peak value of the output signal is lower than the peak value in "Open / Open". On the other hand, when the semiconductor switch 21 is in a closed state and the semiconductor switch 22 is in a closed state, the pulse current flows in the direction of the arrow a shown in FIG. 6, and also flows in the direction of the arrow b. Therefore, as shown in "Close / Close" in FIG. 7, the peak value of the output signal is the lowest. When semiconductor switch 21 is in an open state and semiconductor switch 22 is in an open state, the pulse current does not flow in the direction of arrow a shown in Fig. 6, nor in the direction of arrow b. Therefore, the peak value of the output signal becomes the highest, as shown by "Open / Open" in Fig. 7. In other words, the peak value of the output signal changes every half wave.

[0040] When the peak value of the output signal is less than the peak value threshold, the controller 14 determines that the semiconductor switches 21 and 22 are in the closed state. When the detected peak value is equal to or greater than the peak value threshold and is low, the controller 14 determines that the semiconductor switches 21 are in the closed state and the semiconductor switches 22 are in the open state. When the detected peak value is equal to or greater than the peak value threshold and is high, the controller 14 determines that the semiconductor switches 21 and 22 are in the open state. In this way, in the modified example of this embodiment, the connection states of the semiconductor switches 21 and 22 can be diagnosed.

[0041] The ignition switch of the present invention corresponds to the "system switch" of the present invention, the semiconductor switch 21 corresponds to the "first semiconductor switch" of the present invention, and the semiconductor switch 22 corresponds to the "second semiconductor switch" of the present invention.

[0042] Although the embodiments of the present invention have been described above, these embodiments are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Explanation of symbols]

[0043] 1 power supply 2 Relay Switch 3 Battery 4. Load 10 Relay diagnostic device 11 Pulse transformer 11a Primary coil 11b Secondary coil 12 Input Lines 13 Output Line 14 Controller 15 Capacitor 21, 22 Semiconductor switch

Claims

1. A relay diagnostic device for diagnosing a connection state of a relay switch connected between a power source and a load, comprising: a pulse transformer having a primary coil and a secondary coil, the secondary coil being connected in parallel with the relay switch; a controller that inputs a pulse signal to the primary coil and diagnoses a connection state of the relay switch based on an output signal output from the primary coil.

2. 2. The relay diagnostic device according to claim 1, The controller: Detecting a primary impedance of the pulse transformer based on the output signal; A relay diagnostic device that diagnoses a connection state of the relay switch based on the amount of change in the primary side impedance.

3. 3. The relay diagnostic device according to claim 1, The controller: When the peak value of the output signal is high, it is determined that the relay switch is in an open state. The relay diagnostic device determines that the relay switch is in a closed state when the peak value of the output signal is low.

4. 3. The relay diagnostic device according to claim 1, The controller is a relay diagnostic device that diagnoses the start-up state of a system including the load according to the peak value of the output signal.

5. 5. The relay diagnostic device according to claim 4, The controller: When a system switch for switching the system on and off is on, a resolution for detecting the output signal is increased; A relay diagnostic device that reduces the resolution for detecting the output signal when the system switch is off.

6. 3. The relay diagnostic device according to claim 1, a relay diagnostic device having a capacitor connected between the relay switch and the secondary coil;

7. 3. The relay diagnostic device according to claim 1, The relay switch includes a first semiconductor switch and a second semiconductor switch connected in series, a forward direction of a parasitic diode included in the first semiconductor switch is opposite to a conduction direction of a current flowing from the power supply to the load, a forward direction of a parasitic diode included in the second semiconductor switch is the same as a conduction direction of a current flowing from the power supply to the load, The controller is a relay diagnostic device that diagnoses connection states of the first semiconductor switch and the second semiconductor switch in accordance with the peak value of the output signal.

8. A relay diagnosis method executed by a processor for diagnosing a connection state of a relay switch connected between a power source and a load, comprising: The processor, A pulse signal is input to a primary coil included in a pulse transformer having a secondary coil connected in parallel with the relay switch, A diagnostic method for diagnosing a connection state of the relay switch based on an output signal output from the primary coil.

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