Control device for vehicle charging relay circuit

Abstract

To provide a control device of a charging relay circuit for a vehicle capable of suppressing freezing of a relay without providing a dedicated component.SOLUTION: An AC circuit configured to supply power supplied from the AC charging device to the power storage device; and a DC circuit configured to supply power supplied from the DC charging device to the power storage device, wherein the AC circuit includes a transformer and an AC / DC converter, the control device is configured to control the AC-DC converter to cause a current to flow through the AC circuit (step S1) in a state in which the power storage device and the AC circuit are connected to each other by the C-contact relay when a system of the electric vehicle is stopped for a predetermined time or more under a temperature equal to or lower than a predetermined temperature (Yes in steps S6, S3, and S5).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle charging relay circuit that can charge an electricity storage device with power supplied from a charging device external to the vehicle by bringing the relay circuit into a conductive state. [Background technology]

[0002] Patent Document 1 describes an anti-icing device that includes an electric heating element configured by enclosing an electric heating wire in an aluminum nitride plate and fixed to an anti-icing section, and a charger that is charged by receiving power from a power source and energizes the electric heating element. This anti-icing device includes a heating element circuit relay provided between the charger and the electric heating element, and is configured to periodically switch the heating element circuit relay to a conductive state. Furthermore, a power supply circuit relay is provided between the power source and the charger, and is configured to switch the power supply circuit relay to a non-conductive state when the heating element circuit relay is switched to a conductive state. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-240272 Summary of the Invention [Problem to be solved by the invention]

[0004] An electrical circuit connecting a vehicle's onboard power storage device and an inlet to which an external power source is connected typically includes a mechanical relay that establishes electrical continuity by bringing metal contacts into contact with each other. Therefore, if the vehicle is exposed to a low-temperature environment for a relatively long period of time while the vehicle's systems are stopped, such as when the accessory power source is turned off, the relay may freeze and become unable to be turned off. Furthermore, if the relay is a C-type relay, the relay may freeze at one of the contacts, preventing it from switching to the other contact, or ice may form between the contacts and prevent it from being turned on. If the anti-icing device described in Patent Document 1 were to be installed to prevent such relay icing, the relay circuit would become larger and the control required to switch the anti-icing device's relay may become complicated.

[0005] The present invention has been made in response to the above technical problems, and aims to provide a control device for a vehicle charging relay circuit that can suppress icing of the relay without the need for dedicated components. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a control device for a vehicle charging relay circuit, which includes a vehicle power storage device, an AC circuit that supplies power supplied from an AC charging device external to the vehicle to the power storage device, and a DC circuit that supplies power supplied from a DC charging device external to the vehicle to the power storage device, wherein the AC circuit includes a transformer having a primary coil through which current supplied from the AC charging device flows and a secondary coil through which current corresponding to magnetic flux generated by the primary coil flows, and an AC / DC converter that can convert the AC current output from the transformer to DC current, and further includes a C-contact relay that switches which of the AC circuit and the DC circuit is connected to the power storage device, and a controller that controls the C-contact relay and the AC / DC converter, wherein the controller is configured to control the AC / DC converter to supply current to the AC circuit while the power storage device and the AC circuit are connected by the C-contact relay when the vehicle's system is stopped for a predetermined period of time or more in an environment where the temperature is below a predetermined temperature. [Effects of the Invention]

[0007] According to the present invention, the vehicle includes an AC circuit that supplies power supplied from an AC charging device to a power storage device, and a DC circuit that supplies power supplied from a DC charging device to the power storage device. The AC circuit includes a transformer having a primary coil through which current supplied from the AC charging device flows and a secondary coil through which current corresponding to magnetic flux generated by the primary coil flows, and an AC / DC converter that can convert the AC current output from the transformer to DC current. The AC circuit also includes a C-contact relay that switches between the AC circuit and the DC circuit and the circuit that is connected to the power storage device. Therefore, by connecting the AC circuit and the power storage device through the C-contact relay and placing the AC / DC converter in a conductive state, a closed circuit is formed in which the power storage device and the AC circuit are connected. Therefore, when the vehicle system is stopped for a predetermined period of time in an environment where the temperature is below a predetermined temperature, current flows through the AC circuit by placing the AC / DC converter in a conductive state while the power storage device and the AC circuit are connected through the C-contact relay. As a result, when a current flows through the C-contact relay, the C-contact relay is heated by Joule heat that corresponds to the electrical resistance at the contact and the value of the current flowing through it. Therefore, the C-contact relay can be heated using components of the AC circuit, and freezing of the C-contact relay can be prevented without providing a dedicated part for heating the C-contact relay. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an electrical circuit diagram illustrating an example of a vehicle charging relay circuit according to an embodiment of the present invention. [Figure 2] FIG. 10 is an electric circuit diagram for explaining an example in which a DC inlet and a power storage device are connected. [Figure 3] 4 is a flowchart illustrating an example of control executed by a control device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples of specific implementations of the present invention and are not intended to limit the present invention.

[0010] An example of a vehicle charging relay circuit according to an embodiment of the present invention is shown in Figure 1. The vehicle charging relay circuit (hereinafter simply referred to as charging relay circuit) 1 shown in Figure 1 is configured to be able to charge the vehicle's power storage device 2 from both an AC charging device (not shown) and a DC charging device (not shown) provided outside the vehicle.

[0011] The power storage device 2 can be configured in the same manner as power storage devices installed in conventional electric vehicles or hybrid vehicles. Specifically, it can be configured using secondary batteries such as lithium-ion batteries or nickel-metal hydride batteries, or electric double layer capacitors. In other words, the power storage device 2 is configured using a direct current charging device. Note that the power storage device 2 may also be configured using a battery pack in which multiple batteries are arranged in series.

[0012] A positive bus 3 is connected to the positive terminal of the power storage device 2, and a negative bus 4 is connected to the negative terminal. A motor (MG) 6 serving as a driving power source for the vehicle is connected to the positive bus 3 and the negative bus 4 via an inverter (INV) 5. The motor 6 can be configured similarly to motors used as driving power sources in conventional electric vehicles and hybrid vehicles, and can be configured as a synchronous motor or an induction motor, for example. The motor 6 shown in FIG. 1 is a three-phase AC synchronous motor. Therefore, the inverter 5 includes multiple transistors (not shown) and is configured to convert DC power output from the power storage device 2 into three-phase AC power by controlling these transistors. In addition to functioning as an electric motor, the motor 6 is configured to function as a generator that generates power by rotating the output shaft of the motor 6. The generated AC power is converted into DC power by the inverter 5, and can be used to charge the power storage device 2.

[0013] The charging relay circuit 1 is also provided with an AC inlet 7 into which the plug of an AC charging device provided outside the vehicle is inserted, and a DC inlet 8 into which the plug of a DC charging device provided outside the vehicle is inserted, and is also provided with a C-contact relay 9 for selecting the inlet 7 (8) to be connected to the storage device 2.

[0014] The C-contact relay 9 is an electromagnetic mechanical relay that can switch between a state in which the power storage device 2 and the AC inlet 7 are connected as shown in FIG. 1 and a state in which the power storage device 2 and the DC inlet 8 are connected as shown in FIG. 2 in response to a command signal (power) from a controller 10 (described later). The contacts are made of a metal material with relatively high electrical conductivity to reduce electrical resistance. In FIGS. 1 and 2, energized portions are indicated by solid lines, and de-energized portions are indicated by dashed lines. The C-contact relay 9 is configured to establish electrical continuity between the power storage device 2 and the AC circuit 11 (described later) when no command signal is input from the controller 10. In other words, the C-contact relay 9 establishes electrical continuity between the power storage device 2 and the AC circuit 11 except when a plug is inserted into the DC inlet 8.

[0015] 1, a C-contact relay 9 is provided on each of the positive bus bar 3 and the negative bus bar 4. In an AC circuit 11 between the C-contact relay 9 and the AC inlet 7, a PFC (Power Factor Correction) circuit 12 for improving the power factor by making the AC power input from the AC inlet 7 closer to a sine wave, an isolation transformer 13, and an AC / DC conversion circuit 14 are provided in series in this order from the AC inlet 7 side. This isolation transformer 13 corresponds to the "transformer" in the embodiments of the present invention, and the AC / DC conversion circuit 14 corresponds to the "AC / DC converter" in the embodiments of the present invention.

[0016] The PFC circuit 12 is provided with a transistor 12a for converting the waveform of AC power, and is configured to make the AC power closer to a sine wave by controlling a signal output to the transistor 12a.

[0017] Isolation transformer 13 includes primary coil 13a through which current output from PFC circuit 12 (i.e., current output from the AC charging device) flows, and secondary coil 13b connected to AC / DC conversion circuit 14. Therefore, a magnetic flux is generated when a current flows through primary coil 13a, and a current (induced current) corresponding to the magnetic flux flows through secondary coil 13b. That is, a current generated in secondary coil 13b is the current passed through primary coil 13a multiplied by the ratio of the number of turns of primary coil 13a to that of secondary coil 13b.

[0018] The AC / DC conversion circuit 14 includes a transistor 14a for converting an AC current into a DC current. That is, the AC current is converted into a DC current by controlling a signal output to the transistor 14a.

[0019] 1, an AC charging device is plugged into the AC inlet 7 and transistor 12a in PFC circuit 12 is controlled, causing an AC current to flow through primary coil 13a. In this state, contact C relay 9 connects power storage device 2 to AC circuit 11, and transistor 14a in AC / DC conversion circuit 14 is controlled, causing an induced voltage to be generated in secondary coil 13b in isolation transformer 13. As a result, a voltage is applied to power storage device 2, allowing it to be charged.

[0020] Furthermore, in the AC circuit 11, by turning on (conducting) the transistor 14a in the AC / DC conversion circuit 14, the storage device 2 and the secondary coil 13b in the isolation transformer 13 are connected as a closed circuit, and a current flows according to the resistance value between the storage device 2 and the secondary coil 13b.

[0021] 1 and 2, the C-contact relay 9 and the DC inlet 8 are connected in series. Therefore, by connecting the plug of a DC charging device to the DC inlet 8 and connecting the DC circuit 15 between the C-contact relay 9 and the DC inlet 8 to the power storage device 2 via the C-contact relay 9, a voltage is applied from the DC charging device to the power storage device 2, thereby enabling the power storage device 2 to be charged.

[0022] 1 and 2 is configured in accordance with the NACS (North American Charging Standard) standard. That is, the DC inlet 8 is configured so that an AC charging device having a plug connectable to the inlet 8 can be connected to the DC inlet 8. Therefore, the DC circuit 15 is provided with a branch circuit 16 connected to the PFC circuit 12 in the AC circuit 11. Therefore, when the plug of an AC power supply device is connected to the DC inlet 8, the C-contact relay 9 connects the power storage device 2 to the AC circuit 11 and controls the transistor 12a in the PFC circuit 12 and the transistor 14a in the AC / DC conversion circuit 14. As a result, a voltage is applied to the power storage device 2 from the DC inlet 8 via the AC circuit 11, and the power storage device 2 is charged.

[0023] As described above, there is provided a controller 10 for controlling the C-contact relay 9 and the transistors 12a, 14a. Like controllers provided in conventional vehicles, this controller 10 is configured to receive signals from various sensors provided in the vehicle, determine an output signal based on the input signals and pre-stored arithmetic expressions, and control the C-contact relay 9 and the transistors 12a, 14a based on the determined output signal.

[0024] Specifically, signals are input to the controller 10 from a temperature sensor 17 that detects the temperature near the charging relay circuit 1 or the temperature outside the vehicle, a voltmeter (not shown) that detects the output voltage of the storage device 2, a resolver (not shown) that detects the rotation speed of the motor 6, and the like.

[0025] As described above, since the contacts of the C-contact relay 9 are made of a metal material, moisture contained in the air may adhere to the contacts and freeze when the ambient temperature is low. Therefore, for example, if the contacts of the C-contact relay 9 freeze while the power storage device 2 is connected to the AC circuit 11, ice may accumulate between the contacts, preventing electrical continuity even when a plug is inserted into the DC inlet 8 and the C-contact relay 9 is switched to connect the power storage device 2 to the DC circuit 15. Alternatively, if the C-contact relay 9 freezes while the power storage device 2 is connected to the DC circuit 15, the C-contact relay 9 may not be able to switch, preventing charging, even when a plug is inserted into the AC inlet 7.

[0026] Therefore, the control device in this embodiment of the present invention is configured to periodically pass a current through the C-contact relay 9 to generate Joule heat according to the value of the current flowing through the C-contact relay 9, thereby heating the C-contact relay 9 and preventing freezing of the C-contact relay 9. A flowchart illustrating an example of this control is shown in Figure 3.

[0027] 3, first, it is determined whether the vehicle system is stopped (step S1). This step S1 is a step for determining whether various heat-generating parts (e.g., motor 6) provided in the vehicle are not operating, and therefore, the determination may be made based on whether accessories are turned off or not.

[0028] If the system is not off and the result of step S1 is negative, a counter (described later) is cleared (step S2), and this routine is temporarily terminated. Conversely, if the system is off and the result of step S1 is positive, it is determined whether the outside air temperature is below a predetermined temperature (e.g., 0 degrees) (step S3). This step S3 is a step for determining whether the outside air temperature has dropped to a temperature at which the C-contact relay 9 freezes, and this determination can be made based on the temperature detected by the temperature sensor 17.

[0029] If the outside air temperature is higher than a predetermined temperature and the answer is negative in step S3, the routine proceeds to step S2, where the counter is cleared, and the routine ends. Conversely, if the outside air temperature is equal to or lower than a predetermined temperature and the answer is positive in step S3, the counter is incremented (step S4), and it is determined whether the counter is equal to or greater than a predetermined value (step S5). The predetermined value in step S5 is a value (time) determined so that the contacts of the C-contact relay 9 do not freeze, and is determined in advance based on experiments, simulations, etc.

[0030] If the counter is less than the predetermined value and the determination in step S5 is negative, the routine is immediately terminated. Conversely, if the counter is equal to or greater than the predetermined value and the determination in step S5 is affirmative, current is passed through the AC circuit 11 for a predetermined time (step S6). Specifically, by controlling the transistor 14a in the AC / DC conversion circuit 14, a current is passed through the closed circuit formed between the power storage device 2 and the secondary coil 13b. At this time, the current value passing through the C-contact relay 9 may be a current value that is sufficient to heat the contact of the C-contact relay 9 to a temperature higher than 0°C, and may be a relatively constant current. The value of the current passed through may be changed depending on the outside air temperature detected by the temperature sensor 17.

[0031] After energizing the AC circuit 11 for a predetermined time, the counter is cleared (step S2) and this routine is temporarily terminated.

[0032] Although the example has been described in which the power storage device 2 and the AC circuit 11 are connected in advance by the C-contact relay 9, it is also possible to configure the power storage device 2 and the AC circuit 11 to be connected by the C-contact relay 9 after it is determined that the counter is equal to or greater than a predetermined value, or after it is determined that the counter is equal to or greater than another predetermined value that is smaller than the above-mentioned predetermined value, and then to energize the AC circuit 11. Here, the above-mentioned other predetermined value can be set to a time period that will prevent the contacts of the C-contact relay 9 from freezing.

[0033] The charging relay circuit 1 described above includes an AC circuit 11 that supplies power supplied from an AC charging device to the power storage device 2, and a DC circuit 15 that supplies power supplied from a DC charging device to the power storage device 2. The AC circuit 11 includes a transformer 13 having a primary coil 13a through which current supplied from the AC charging device flows and a secondary coil 13b through which current corresponding to magnetic flux generated by the primary coil 13a flows, and an AC / DC conversion circuit 14 that can convert the AC current output from the transformer 13 into DC current. The circuit 11 (15) connected to the power storage device 2 is switched by a C-contact relay 9. Therefore, by connecting the AC circuit 11 and the power storage device 2 by the C-contact relay 9 and bringing the AC / DC conversion circuit 14 into a conductive state, a closed circuit is formed in which the power storage device 2 and the AC circuit 11 are connected.

[0034] Therefore, when the system is stopped for a predetermined time or longer in an environment where the vehicle temperature is below a predetermined temperature, the AC / DC conversion circuit 14 is brought into a conductive state with the power storage device 2 and the AC circuit 11 connected by the C-contact relay 9, and current flows through the AC circuit 11. As a result, when current flows through the C-contact relay 9, the C-contact relay 9 is heated by Joule heat that corresponds to the electrical resistance at its contacts and the value of the current being passed. Therefore, the C-contact relay 9 can be heated using the components of the AC circuit 11, and freezing of the C-contact relay 9 can be prevented without providing a dedicated component for heating the C-contact relay 9 or the like. [Explanation of symbols]

[0035] 1 Charging relay circuit 2. Energy storage device 7 AC inlet 8 DC inlet 9-contact relay 10 Controllers 11 AC circuit 12 PFC circuit 12a, 14a Transistor 13 Isolation transformer 13a, 13b coil 14 AC / DC conversion circuit 15 DC circuit 17 Temperature Sensor

Claims

1. A control device for a vehicle charging relay circuit, comprising: a vehicle power storage device; an AC circuit for supplying power supplied from an AC charging device external to the vehicle to the power storage device; and a DC circuit for supplying power supplied from a DC charging device external to the vehicle to the power storage device, the AC circuit includes a transformer having a primary coil through which current supplied from the AC charging device flows and a secondary coil through which current corresponding to magnetic flux generated by the primary coil flows, and an AC / DC converter capable of converting the AC current output from the transformer into a DC current; a C-contact relay that switches between the AC circuit and the DC circuit, which circuit is connected to the power storage device; a controller for controlling the contact C relay and the AC / DC converter; The controller When the vehicle system is stopped for a predetermined period of time or longer in an environment where the temperature of the vehicle is equal to or lower than a predetermined temperature, the AC / DC converter is controlled to allow a current to flow through the AC circuit while the C-contact relay connects the power storage device and the AC circuit.

1. A control device for a vehicle charging relay circuit.

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