JP6623794B2 - Relay sticking detection system - Google Patents

Description

  The present invention relates to a relay sticking detection system, and more particularly to a system for detecting sticking of a relay provided between a battery and an electric device in a battery-powered vehicle.

  An electric vehicle or a hybrid car is equipped with a battery and various electric devices electrically connected to the battery. As such an electric device, for example, a power control unit (PCU) for controlling a motor generator functioning as a power source or a generator for driving a vehicle is given. In recent vehicles, AC power from an external AC power supply is converted into DC power so that the battery can be charged (plug-in charging) by power from an external AC power supply such as a home power supply or a charging stand. A charger (AC-DC converter) for conversion is provided, and the charger is also one of the electric devices.

  A relay is provided in a path between the battery and the PCU so that power is not supplied to the PCU when the PCU does not need to operate, for example, when the ignition is off. Such a relay is called a system main relay. Further, a relay is also provided in a path between the battery and the charger in order to electrically disconnect the battery and the charger when the charging of the battery is completed. Such a relay is called a charge relay. Thus, an electric vehicle or a hybrid car is provided with a relay in a path between a battery and an electric device.

  The contact of the relay provided in the path between the battery and the electric device may be fixed in a closed state (on state) due to welding or the like due to a life or an excessive current flowing. In view of this, a technique for detecting such sticking of the contact point of the relay has been conventionally proposed.

  For example, Patent Literature 1 discloses a positive switch (contact) provided between a positive electrode of a battery and an electric device and a negative switch (contact) provided between a negative electrode of a battery and an electric device. A technique for efficiently detecting the sticking is disclosed. Specifically, an alternating current is applied to the circuit including the battery and the two switches, and when the two switches are not fixed (that is, when both the switches are open), By utilizing the fact that the amplitudes of the alternating currents detected at predetermined positions in the circuit are different from each other when at least one of them is fixed (that is, at least one of the switches is closed), The sticking of the two switches is detected based on the detected amplitude value of the current.

JP-A-2015-35708

  When the charging plug is connected to an external AC power supply and AC power from the external AC power supply is supplied into the vehicle, noise derived from the external AC power supply may propagate to a circuit including a battery and a relay. Such noise is, for example, an induction noise or a radiation noise caused by an electromagnetic wave flying in space from an AC line through which AC power from an external AC power source flows. These noises may fluctuate in amplitude at a predetermined frequency (for example, the frequency of an external AC power supply or a frequency multiple thereof).

  For example, as described in Patent Document 1, when adopting a method of applying an AC signal to a circuit and detecting the fixation of a relay contact by detecting the amplitude of the applied AC signal, a charging plug is connected. In a state where the AC power is supplied from an external AC power supply to the vehicle, the above-described noise affects the detection amplitude value, and erroneous detection occurs in the process of detecting the sticking of the contact point of the relay. There was a problem.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle having a charging plug connected to an external AC power supply for charging a battery, in detecting the sticking of a contact point of a relay provided in a path between the battery and the electric device, to detect an error. It is to reduce the possibility of detection.

The present invention is a relay sticking detection system mounted on a vehicle, comprising: a battery; a first relay provided on a path between the battery and the first electric device; and a relay between the battery and the second electric device. A power supply circuit including a second relay provided in a path, and a charging plug connected to an external AC power supply for charging the battery , and detecting sticking of a contact of the first relay or the second relay. An AC signal applying means for supplying the AC signal to the power supply circuit, and a position where the amplitude value of the AC signal is different between the case where the contact of the first relay or the second relay is in the open state and the case where the contact is in the closed state. An amplitude detecting means for detecting an amplitude of the AC signal; a plug connection state determining means for determining whether or not the charging plug is connected to the external AC power supply; and Based on the amplitude of the AC signal amplitude detecting means detects when not connected to an AC power source, and a fixing detection means for detecting sticking of the contacts of the first relay and said second relay, the flow path through the first stray capacitance between the ground member before Symbol AC signal before and Symbol first electric apparatus when the first relay is stuck, wherein, when the second relay is stuck An AC signal flows through a path that passes through a second stray capacitance between the second electric device and the grounding member, and the amplitude detection unit detects the AC signal according to a difference between the first stray capacitance and the second stray capacitance. The amplitude of the AC signal is between the case where the first relay and the second relay are not fixed, the case where the first relay is fixed, and the case where the second relay is fixed. Are different from each other.

  According to the above configuration, in the system for detecting the fixation of the contact point of the relay provided in the path between the battery and the electric device by detecting the amplitude of the AC signal given to the power supply circuit, The sticking of the contacts of the relay is detected based on the amplitude of the AC signal detected when the relay is not connected to the AC power supply. This makes it possible to detect sticking of the contacts of the relay while eliminating the influence of noise derived from the external AC power supply.

  According to the present invention, in a vehicle having a charging plug connected to an external AC power supply for charging a battery, an erroneous detection of sticking of a contact point of a relay provided in a path between the battery and the electric device is performed. The possibility of detection can be reduced.

It is a schematic diagram of a configuration of a relay sticking detection system according to the present embodiment. FIG. 4 is a diagram illustrating a flow path of an alternating current when a contact of a system main relay is fixed. FIG. 3 is a diagram illustrating a flow path of an alternating current when a contact of a charge relay is fixed. It is a flowchart which shows the flow of a process of the relay sticking detection system which concerns on this embodiment.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration diagram of a relay sticking detection system 10 according to the present embodiment. The relay sticking detection system 10 is mounted on a vehicle including a battery and an electric device, such as an electric vehicle or a hybrid car.

  The relay sticking detection system 10 has a power supply circuit 12. The power supply circuit 12 supplies power from an external AC power supply such as a home power supply or a charging stand to the power supply circuit 14 for supplying electric power from a battery 18 to be described later to the electric equipment. Is configured to include a charging circuit 16 for charging.

  The power supply circuit 14 includes a battery 18 and a system main relay 20. In the present embodiment, the power supply circuit 14 is a power path when power is supplied from the battery 18 to a PCU 22 described later, or when power is supplied from the PCU 22 to the battery 18.

  The battery 18 is a secondary battery, for example, a lithium ion battery or a nickel hydride battery. The battery 18 is composed of a plurality of small batteries called cells. The output voltage of each cell is about 1.2 V, and several hundred cells are connected in series, so that the battery 18 outputs a DC voltage of 200 V or more.

  The system main relay 20 is provided on a path between the battery 18 and the PCU 22 that constitutes an electric device in the present embodiment. From the viewpoint of suppressing consumption of the power stored in the battery 18, the system main relay 20 disconnects the electrical connection between the battery 18 and the PCU 22 when it is not necessary to supply power to the PCU 22, for example, when the ignition is turned off. It is provided to shut off.

  The system main relay 20 has a contact that can be switched between an open state and a closed state under the control of the ECU 40 described later. When the contact opens and closes, the electrical disconnection and connection between the battery 18 and the PCU 22 are switched. Can be As shown in FIG. 1, the system main relay 20 has two contacts (contact 20a and contact 20b). The contact 20a is provided in the middle of the positive electrode line 18a connected to the positive electrode of the battery 18, and the contact 20b is provided in the middle of the negative electrode line 18b connected to the negative electrode of the battery 18.

  The two contacts are opened and closed at the same timing under the control of the ECU 40. By switching between electrical disconnection and connection between the battery 18 and the PCU 22 at the two contacts, the fault tolerance of the system main relay 20 is improved. Specifically, even if one of the two contacts is fixed, the power supplied to the PCU 22 can be cut off by opening the other contact.

  The PCU 22 as an electric device controls a motor generator (not shown) functioning as a drive source of a vehicle and a generator. Specifically, PCU 22 receives electric power supplied from battery 18 and operates using the motor generator as a drive source, or supplies electric power generated by the motor generator to battery 18.

  Since the PCU 22 is disposed close to a grounding member such as a vehicle body, a stray capacitance 22a exists between the PCU 22 and the grounding member. As will be described later, the stray capacitance 22a forms a path through which an AC signal for detecting the sticking of the contacts 20a and 20b of the system main relay 20 flows.

  The electric device connected to the system main relay 20 may be any electric circuit or load, and is not limited to the PCU 22. For example, it may be a motor generator controlled by the PCU 22, a circuit for driving an air conditioner provided in the vehicle, the air conditioner itself, a charger 28 described later, or the like.

  The charging circuit 16 includes a charging plug 24, an AC line 26, a charger 28, a DC line 30, and a charge relay 32.

  The charging plug 24 is connected to an external AC power supply for charging the battery 18. When the charging plug 24 is connected to the external AC power supply, AC power from the external AC power supply is supplied to the AC line 26 connected to the charging plug 24. The AC line 26 is also connected to a charger 28, and AC power from an external AC power supply is input to the charger 28.

  The charger 28 as an electric device converts AC power from an external AC power supply into DC power. That is, the charger 28 has an AC-DC conversion function. The DC power converted by the charger 28 is supplied to a DC line 30 connected to the battery 18.

  The charger 28 transmits plug connection information indicating the connection state of the charging plug 24 to the external AC power supply of the charging plug 24 to the ECU 40. Specifically, when AC power is supplied to charger 28, a signal indicating that charging plug 24 is connected to an external AC power source is transmitted to ECU 40, and AC power is supplied to charger 28. If not, a signal indicating that the charging plug 24 is not connected to the external AC power supply is transmitted to the ECU 40. That is, the charger 28 also functions as a plug connection state determination unit that determines whether the charging plug 24 is connected to an external AC power supply.

  Similarly to the PCU 22, the stray capacitance 28a exists between the charger 28 and the ground member because the charger 28 is disposed close to the ground member. As will be described later, the stray capacitance 28a forms a path through which an AC signal for detecting the sticking of the contacts 32a and 32b of the charge relay 32 described later flows.

  Charge relay 32 is provided in the middle of DC line 30, that is, provided on a path between charger 28 and battery 18. The charge relay 32 has a contact that can be switched between an open state and a closed state under the control of the ECU 40. When the contact opens and closes, the electrical disconnection and connection between the charger 28 and the battery 18 are switched. . Like the system main relay 20, the charge relay 32 also has two contacts (contacts 32a and 32b) from the viewpoint of improving fault tolerance. The contact 32a is provided between the charger 28 and the positive electrode of the battery 18, and the contact 32b is provided between the charger 28 and the negative electrode of the battery 18.

  The two contacts are opened and closed at the same timing. Specifically, when the charging plug 24 is connected to the external AC power supply, the two contacts are closed, and when the charging of the battery 18 is completed or when the charging plug 24 is disconnected from the external AC power supply, the two contacts are closed. The two contacts are open.

  When the charging plug 24 is connected to an external AC power supply, the positive electrode line 18a, the negative electrode line 18b, and the DC line 30 have induced noise due to electromagnetic waves flying in the air from the AC line 26 through which the AC power flows. Alternatively, radiation noise may propagate. These noises originating from the external AC power supply can be varied in amplitude at the frequency of the external AC power supply or a multiple thereof.

  The relay sticking detection system 10 outputs an AC signal for detecting sticking of contacts of a system main relay 20 and a charge relay 32 (hereinafter, both relays may be collectively referred to as “detection target relay”) in a power supply circuit 12. An AC voltage source 34 as an AC signal applying means for supplying the power supply circuit 12 and a current detecting unit 36 as an amplitude detecting means for detecting an amplitude value of the AC signal supplied to the power supply circuit 12.

  The AC voltage source 34 applies an AC voltage to the power supply circuit 12 in order to detect the sticking of the contact of the detection target relay. The AC voltage applied by the AC voltage source 34 generates an AC current as an AC signal in the path from the AC voltage source 34 to the power supply circuit 12 and in the power supply circuit 12. In the present embodiment, the AC voltage from the AC voltage source 34 is applied to the power supply circuit 12 from the negative electrode line 18b via the coupling capacitor 38 for blocking the DC component.

  The current detector 36 is, for example, an ammeter, and detects an amplitude value of an AC current generated by the AC voltage applied by the AC voltage source 34. In the present embodiment, the current detector 36 is provided between the AC voltage source 34 and the negative electrode line 18b.

  The relay sticking detection system 10 has an ECU (engine control unit) 40 for controlling each part of the system. The ECU 40 includes, for example, a microprocessor. The ECU 40 controls each unit provided in the relay stuck detection system 10 according to a control program stored in a storage unit (not shown) of the relay stuck detection system 10. For example, the ECU 40 performs control to open and close the contacts of the system main relay 20 and the charge relay 32.

  The ECU 40 detects the sticking of the contact point of the detection target relay based on the amplitude value of the alternating current detected by the current detection unit 36. That is, the ECU 40 also functions as a sticking detection unit. Hereinafter, a method in which the ECU 40 detects the sticking of the contact of the detection target relay will be described.

  As a premise, the sticking detection process for detecting the sticking of the contact of the detection target relay is executed after performing control to open the contact of the detection target relay. In the present embodiment, in order to detect the sticking of both the contacts of the system main relay 20 and the charge relay 32, the contacts of the system main relay 20 and the charge relay 32 are opened, and the sticking detection processing of these contacts is performed. Do.

  Consider a case where the system main relay 20 and the charge relay 32 are normal. In the sticking detection process, if the system main relay 20 and the charge relay 32 are normal (if the contacts are not fixed), the contacts of the system main relay 20 and the charge relay 32 are opened as shown in FIG. Has become.

  At this time, since the ends of the positive electrode line 18a and the negative electrode line 18b on the side of the system main relay 20 and the end of the DC line 30 on the side of the charge relay 32 are open, the AC voltage is supplied by the AC voltage source 34. Even if it is applied to the power supply circuit 12, no AC current flows between the AC voltage source 34 and the power supply circuit 12 and in the power supply circuit 12. Therefore, the amplitude value detected by the current detection unit 36 is substantially zero.

  It is assumed that the contact 20b of the system main relay 20 is fixed. FIG. 2 shows a state where the contact 20b is fixed. If the contact 20b is stuck, the contact 20b will be kept closed even if the ECU 40 controls to open the contact of the system main relay 20. In this state, as shown in FIG. 2, an AC current path A having a ground point, an AC voltage source 34, a current detector 36, a coupling capacitor 38, a negative electrode line 18b, a contact 20b, a PCU 22, a floating capacitance 22a, and a ground point. Is formed. Therefore, in this case, the AC voltage applied from the AC voltage source 34 causes an AC current having a predetermined amplitude value to flow through the AC current path A. The amplitude value is determined by the capacitance of the stray capacitance 22a and the like. Similarly, even when the contact 20a is fixed, an AC current path (ground point, AC voltage source 34, current detection unit 36, coupling capacitor 38, positive electrode line 18a, contact 20a, PCU 22, floating capacitance 22a, and ground point) (Not shown), an alternating current having a predetermined amplitude value flows.

  Consider a case where the contact 32b of the charge relay 32 is fixed. FIG. 3 shows how the contact 32b is fixed. If the contact 32b is fixed, the contact 32b will be kept closed even if the ECU 40 performs control to open the contact of the charge relay 32. In this state, as shown in FIG. 3, an alternating current of a ground point, an AC voltage source 34, a current detector 36, a coupling capacitor 38, a negative electrode line 18b, a contact 32b, a charger 28, a stray capacitance 28a, and a ground point. Path B is formed. Therefore, in this case, the AC voltage applied from the AC voltage source 34 causes an AC current having a predetermined amplitude value to flow through the AC current path B. The amplitude value is also determined by the capacitance of the stray capacitance 28a and the like. Similarly, when the contact point 32a is fixed, the AC current of the ground point, the AC voltage source 34, the current detector 36, the coupling capacitor 38, the positive electrode line 18a, the contact 32a, the charger 28, the stray capacitance 28a, and the ground point An alternating current having a predetermined amplitude value flows through a path (not shown).

  As described above, at the position where the current detecting unit 36 detects the amplitude value of the AC current (between the AC voltage source 34 and the power supply circuit 12 in this embodiment), all the contacts of the system main relay 20 and the charge relay 32 are provided. Are in the open state, and the amplitude of the AC current generated by the AC voltage applied by the AC voltage source 34 is different from each other depending on whether one of the contacts of the two relays is fixed. As long as this condition is satisfied, the current detector 36 may detect the amplitude value of the alternating current at another position. For example, the amplitude value of the alternating current in the line connected to the positive electrode of the battery 18 or the amplitude value of the alternating current in the line connected to the negative electrode of the battery 18 may be detected.

  As described above, it is possible to detect the sticking of the contact of the detection target relay based on the detected amplitude value of the current detection unit 36. Specifically, the amplitude value of the AC current flowing through the AC current paths A and B, and the amplitude value (almost 0) detected by the current detection unit 36 when the contacts of the system main relay 20 and the charge relay 32 are open. A threshold value, which is a value between, is determined in advance. Thus, the ECU 40 determines that the system main relay 20 and the charge relay 32 are normal when the amplitude value detected by the current detection unit 36 is less than the threshold, and that the system main relay 20 and the charge relay 32 when the amplitude value is equal to or greater than the threshold. It is possible to detect that at least one of the contacts of the charge relay 32 is fixed.

  If there is a significant difference between the amplitude value of the AC current flowing through the AC current path A and the amplitude value of the AC current flowing through the AC current path B, the ECU 40 determines the amplitude detected by the current detection unit 36. It is also possible to identify which of the contact of the system main relay 20 and the contact of the charge relay 32 is stuck according to the value.

  Further, in the present embodiment, the amplitude value of the AC current is detected as an AC signal in order to detect the sticking of the contact point of the detection target relay. However, an AC voltage may be detected as the AC signal. For example, a resistance element may be provided between the AC voltage source 34 and the power supply circuit 12 to detect the amplitude value of the AC voltage on the negative electrode line 18b. According to this, the sticking of the contact of the detection target relay can be detected based on the fluctuation of the amplitude value of the AC voltage in the negative electrode line 18b that occurs when the contact of the detection target relay is stuck.

  When the above-described detection processing is performed in a state where the charging plug 24 is connected to the external AC power supply, there is a possibility that erroneous detection of fixation of the contact of the detection target relay may occur due to the influence of noise derived from the external AC power supply. Specifically, the current detector 36 may detect an AC current flowing due to the noise derived from the external AC power supply, and the detected amplitude value may be equal to or larger than a predetermined threshold. Then, the ECU 40 erroneously detects that the contact of the detection target relay is fixed even though the contact of the detection target relay is not fixed. Therefore, in the present embodiment, the ECU 40 functions as a plug connection state determination unit that detects that the charging plug 24 is not connected to the external AC power supply in order to prevent erroneous detection due to noise derived from the external AC power supply. As a result, the sticking detection processing of the contact of the relay to be detected based on the amplitude value detected by the current detection unit 36 can be performed only when the charging plug 24 is not connected to the external AC power supply, thereby preventing erroneous detection due to noise. can do.

  Hereinafter, the flow of the sticking detection process in the relay sticking detection system 10 will be described with reference to the flowchart shown in FIG. As shown in the flowchart of FIG. 4, in the present embodiment, the sticking detection process is executed at the timing when the plug-in charging is completed, but the execution timing of the sticking detection process is not limited thereto.

  In step S10, the user connects the charging plug 24 to an external AC power supply. Accordingly, the ECU 40 performs control to close the contact of the charge relay 32. Thus, plug-in charging is started.

  In step S12, the ECU 40 refers to the plug connection information transmitted from the charger 28 and determines whether or not the charging plug 24 has been removed from the external AC power supply. If the charging plug 24 is still connected to the external AC power supply, the process proceeds to step S14, and after waiting for a certain time, the determination is made again in step S12. If the charging plug 24 has been removed from the external AC power supply, the process proceeds to step S16.

  In step S16, the ECU 40 performs control to open the contacts of the system main relay 20 and the charge relay 32. As a result, if the system main relay 20 and the charge relay 32 are normal, the contacts of the respective relays are open, but if at least one of the contacts of the system main relay 20 and the charge relay 32 is fixed, The fixed contact is maintained in the closed state.

  In step S <b> 18, it is determined whether the contacts of the system main relay 20 and the charge relay 32 are fixed. Specifically, the ECU 40 refers to the amplitude value of the AC current detected by the current detection unit 36 in a state where the charging plug 24 is not connected to the external AC power supply, and the amplitude value is equal to or larger than a preset threshold value. In this case, it is determined that one of the contacts of the system main relay 20 and the charge relay 32 is fixed, and if the amplitude value is less than the threshold, the contact of the system main relay 20 and the charge relay 32 has It is determined that all are not fixed.

  As described above, according to this embodiment, based on the amplitude value detected by the current detection unit 36 when the charging plug 24 is not connected to the external AC power supply, the sticking detection processing of the contact of the detection target relay is performed. . Thus, the sticking detection processing can be performed without being affected by noise derived from the external AC power supply, and the possibility of erroneous detection is reduced.

  Although the embodiment according to the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  Reference Signs List 10 relay sticking detection system, 12 power supply circuit, 14 power supply circuit, 16 charging circuit, 18 battery, 18a positive electrode line, 18b negative electrode line, 20 system main relay, 20a, 20b, 32a, 32b contacts, 22 PCU, 22a , 28a stray capacitance, 24 charging plugs, 26 AC lines, 28 chargers, 30 DC lines, 32 charge relays, 34 AC voltage sources, 36 current detectors, 38 coupling capacitors, 40 ECUs.

Claims (1)

A relay sticking detection system mounted on a vehicle,
A battery, a first relay provided on a path between the battery and the first electric device, a second relay provided on a path between the battery and the second electric device, and for charging the battery A power supply circuit including a charging plug connected to an external AC power supply;
AC signal providing means for providing an AC signal to the power supply circuit for detecting the sticking of the contact point of the first relay or the second relay ,
At a position where the amplitude value of the AC signal is different from each other between a case where the contact point of the first relay or the second relay is in an open state and a case where the contact point is in a closed state, amplitude detection means for detecting the amplitude of the AC signal,
Plug connection state determination means for determining whether the charging plug is connected to the external AC power supply,
Sticking detecting means for detecting sticking of the contact of the first relay or the second relay based on the amplitude of the AC signal detected by the amplitude detecting means when the charging plug is not connected to the external AC power supply. When,
With
Flow path through the first stray capacitance between the ground member before Symbol AC signal before and Symbol first electric apparatus when the first relay is stuck, when the second relay is stuck The AC signal flows through a path that passes through a second stray capacitance between the second electric device and a ground member, and the amplitude detection unit determines the amplitude in accordance with a difference between the first stray capacitance and the second stray capacitance. The amplitude of the AC signal to be detected depends on whether the first relay and the second relay are not fixed , when the first relay is fixed, and when the second relay is fixed . Different from each other,
A relay sticking detection system, characterized in that:

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