Vehicle power supply system

Abstract

To accurately determine abnormality of a relay.SOLUTION: A vehicle power supply system comprises: a battery; a power converter having a smoothing capacitor; a voltage sensor; a first relay; a second relay; a third relay; and a control device which executes a start-up process electrically connecting the battery to the power converter. The start-up process includes: a first process to turn on the first relay and the third relay; a second process to monitor voltage detected with the voltage sensor and to detect a predetermined change in the detected voltage; a third process to increment a predetermined count number when the predetermined change is not detected and to turn off the first relay and the third relay; and a fourth process to determine that at least either the first relay or the third relay has abnormality when the count number reaches a predetermined upper limit.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed in this specification relates to a power supply system for vehicles.

Background Art

[0002] Patent Document 1 describes a charging system for vehicles. This charging system includes a battery, a power conversion device connected between the battery and an external charging device and having a smoothing capacitor, a voltage sensor for detecting the voltage of the smoothing capacitor, a first relay provided between the positive electrode of the battery and the power conversion device, a second relay provided between the negative electrode of the battery and the power conversion device, and a control device connected to the voltage sensor and controlling the on / off of each relay. The control device is configured to enable charging of the capacitor (so-called "pre-charge") by the external charging device with the first relay and the second relay off. After pre-charge, the control device determines abnormalities of the first relay and the second relay based on the detected voltage by the voltage sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Depending on the vehicle's driving conditions and ambient temperature, condensation may form on the relay contacts, which can then freeze, causing ice to form on the relay contacts. When ice forms on the relay contacts, the relay cannot be electrically connected even when the relay is turned on. However, the freezing of the relay contacts is temporary and usually resolves without problems due to temperature increases and physical stress from repeatedly turning the relay on and off. In the relay malfunction detection process described above, even temporary malfunctions such as the freezing of relay contacts may be uniformly judged as a relay malfunction, potentially leading to unnecessary replacement of parts.

[0005] In light of the above circumstances, this specification provides a technology for accurately determining relay abnormalities. [Means for solving the problem]

[0006] The technology disclosed herein is embodied in a vehicle power supply system for supplying power to a vehicle load. In a first embodiment, the vehicle power supply system includes a battery, a power converter connected between the battery and the load and having a smoothing capacitor, a voltage sensor for detecting the voltage of the smoothing capacitor, a first relay provided between the positive terminal of the battery and the power converter, a second relay provided between the negative terminal of the battery and the power converter, a third relay connected in parallel with the first or second relay and in series with a resistive element, and a control device connected to the voltage sensor and performing a startup process to electrically connect the battery and the power converter by controlling the on and off states of the first relay, the second relay, and the third relay. The startup process includes a first process of turning on the first relay and the third relay; a second process of monitoring the voltage detected by the voltage sensor after the first process and detecting a predetermined change in the detected voltage; a third process of incrementing a predetermined counter value and turning off the first relay and the third relay if no predetermined change is detected; and a fourth process of determining that an abnormality has occurred in at least one of the first relay or the third relay when the counter value reaches a predetermined upper limit.

[0007] In the power supply system described above, the startup process begins, for example, in response to a user's startup operation. In this startup process, the first and third relays are first turned on, and then the voltage detected by the voltage sensor is monitored. When each relay is functioning correctly, the capacitor charging begins as expected, and a predetermined change in the detected voltage is detected. Conversely, if at least one of the relays malfunctions, the capacitor charging does not begin, and therefore the predetermined change in the detected voltage is not detected. However, the malfunctions in the relays at this time may include temporary malfunctions such as freezing of the relay contacts. Therefore, at this stage, without determining that the relays are malfunctioning, the counter value is incremented, and the process of turning off the first and third relays is executed. Since the startup process is not completed, for example, the user performs the startup operation again, and the process of turning on the first and third relays is executed again. The above process is repeated until the counter value reaches a predetermined upper limit, at which point the relay malfunction is determined. In this case, if the abnormality in the relay is a temporary one, such as freezing of the relay contacts, it is expected that the freezing will be resolved by the physical stimulation caused by the repeated on and off cycles of each relay. That is, before the counter value reaches a predetermined upper limit, the first and third relays will be turned on normally, and a predetermined change in the detection voltage will be detected. As a result, the startup process will proceed normally without being judged as a relay abnormality. In this way, when freezing occurs on the contacts of at least one of the first or third relays, it is possible to avoid being judged as a relay abnormality. Relay abnormalities can be judged with accuracy, and thereby, for example, unnecessary replacement of parts can be avoided. [Brief explanation of the drawing]

[0008] [Figure 1] A diagram illustrating the configuration of the power supply system 10. [Figure 2] A flowchart showing an example of a series of startup processes performed by the control device 16. [Figure 3]Figure 2 shows an example of a time chart for the startup process. [Modes for carrying out the invention]

[0009] In a second embodiment, in the first embodiment described above, the second process may detect when the detected voltage reaches a predetermined threshold voltage as a predetermined change appearing in the detected voltage. With such a configuration, a predetermined change appearing in the detected voltage can be detected relatively easily. However, in other embodiments, the range of change in the detected voltage within a predetermined time or the rate of change of the detected voltage within a predetermined time may be detected as a predetermined change appearing in the detected voltage.

[0010] In a third embodiment, in the second embodiment described above, the threshold voltage may be determined according to the battery voltage. That is, the threshold voltage can be the rated voltage of the battery or the voltage actually output from the battery.

[0011] In a fourth embodiment, in any of the first to third embodiments described above, the startup process may be executed starting from the first process in response to a startup operation by the user, and after the first and third relays are turned off in the third process, the process may be restarted from the first process in response to another startup operation by the user. However, in another embodiment, the control device may, without requiring a startup operation by the user, automatically start the restart from the first process after executing the third process.

[0012] In a fifth embodiment, in any of the first to fourth embodiments described above, the startup process may further include a fifth process in which the second relay is turned on and the third relay is turned off when a predetermined change is detected in the second process. With such a configuration, it is possible to avoid power consumption by a resistive element connected in series with the third relay.

[0013] In the sixth embodiment, in any of the first to fifth embodiments described above, the fifth process may further include a process for resetting the counter value. With this configuration, the counter value represents the number of times the first relay and the third relay are turned on and off in each startup process. This allows a fixed, constant value to be set for the upper limit. Alternatively, in another embodiment, the counter value may be reset before executing the third process in the startup process, for example, at the timing of starting the startup process, or in the first or second process. However, the counter value does not necessarily have to be reset, and its upper limit may be determined as appropriate according to the counter value at the start of the startup process.

[0014] In the seventh embodiment, in any of the first to sixth embodiments described above, the power converter may include at least one of a boost converter that increases the voltage of the power supplied from the battery and an inverter that converts the DC power supplied from the battery into AC power. With such a configuration, the power supplied from the battery can be converted by the power converter into power corresponding to the load on the vehicle.

[0015] In the eighth aspect, in the seventh aspect described above, the power converter may include at least a boost converter. In this case, the smoothing capacitor may be placed either between the battery and the boost converter, or between the boost converter and the load. With such a configuration, ripple current generated in the circuits at the low-voltage end and / or high-voltage end of the boost converter can be suppressed. [Examples]

[0016] Referring to the drawings, the power supply system 10 of this embodiment will be described. The power supply system 10 is mounted on the vehicle and supplies power to the vehicle's load. For example, the load is a first motor MG1 and a second motor MG2, and the two motors MG1 and MG2 are drive motors that drive the vehicle's wheels. That is, the vehicle is a two-motor hybrid vehicle. However, the vehicle does not necessarily have to be equipped with two motors MG1 and MG2 as loads. For example, the vehicle may be equipped with one motor as a load, or it may be equipped with loads other than motors. Therefore, the vehicle does not necessarily have to be a hybrid vehicle, and may be an electric vehicle, a fuel-powered vehicle, or any other vehicle with a drive motor, or it may be an engine-powered vehicle. Some or all of the technology described in this embodiment can also be similarly applied to vehicles that travel on tracks. Furthermore, the vehicle is not limited to those that are driven by a user, but may be remotely controlled by an external device or be autonomous.

[0017] As shown in Figure 1, the power supply system 10 comprises a battery 12, a power converter 14, and a control device 16. The battery 12 is, for example, a lithium-ion battery or a nickel-metal hydride battery, and contains multiple secondary battery cells. The power converter 14 is connected between the battery 12 and two motors MG1 and MG2, and can perform power conversion between them. The control device 16 is communicatively connected to the power converter 14 and can control and monitor the operation of the power converter 14. The control device 16 can adjust the power supplied from the battery 12 and supply it to the two motors MG1 and MG2 by controlling the operation of the power converter 14 in response to user operation, etc.

[0018] As shown in Figure 1, the power converter 14 comprises a DC-DC converter 18, a first inverter 20, and a second inverter 22. The DC-DC converter 18 includes a pair of low-voltage terminals 18a and 18b connected to the battery 12, and a pair of high-voltage terminals 18c and 18d connected to the first inverter 20 and the second inverter 22. The pair of low-voltage terminals 18a and 18b include a positive low-voltage terminal 18a connected to the positive terminal of the battery 12 and a negative low-voltage terminal 18b connected to the negative terminal of the battery 12. The pair of high-voltage terminals 18c and 18d include a positive high-voltage terminal 18c connected to the positive terminal of the first inverter 20 and the positive terminal of the second inverter 22, and a negative high-voltage terminal 18d connected to the negative terminal of the first inverter 20 and the negative terminal of the second inverter 22.

[0019] As shown in Figure 1, the DC-DC converter 18 further comprises a reactor 24, two switching elements 26a and 26b, and two diode elements 28a and 28b. One end of one switching element 26a is connected to the positive terminal of the first inverter 20 and the positive terminal of the second inverter 22. The other end of one switching element 26a is connected to one end of the other switching element 26b and is also connected to the positive terminal of the battery 12 via the reactor 24. The other end of the other switching element 26b is connected to the negative terminal of the battery 12 and is also connected to the negative terminal of the first inverter 20 and the negative terminal of the second inverter 22. The control device 16 can selectively turn the two switching elements 26a and 26b on and off to boost the DC power supplied from the battery 12 to a pair of low-voltage terminals 18a and 18b, and supply the boosted power to each inverter 20 and 22 via a pair of high-voltage terminals 18c and 18d. Thus, the DC-DC converter 18 functions as a boost converter that increases the voltage of the power supplied from the battery 12.

[0020] Although not particularly limited, each of the switching elements 26a and 26b of the DC-DC converter 18 is an RC-IGBT (Reverse conducting Insulated Gate Bipolar Transistor) element. Note that the switching elements 26a and 26b do not necessarily have to be RC-IGBT elements, and for example, MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) elements or other types of switching elements may also be used.

[0021] As shown in FIG. 1, the first inverter 20 is provided between the DC-DC converter 18 and the first motor MG1. The first inverter 20 can convert the DC power from the DC-DC converter 18 into AC power and supply it to the first motor MG1. Similarly, the second inverter 22 is provided between the DC-DC converter 18 and the second motor MG2. The second inverter 22 can convert the DC power from the DC-DC converter 18 into AC power and supply it to the second motor MG2.

[0022] Note that the power conversion device 14 does not necessarily have to include all of the DC-DC converter 18 that functions as a boost converter, the first inverter 20, and the second inverter 22, and it may include at least one of the boost converter or the inverter. Although not particularly limited, the DC-DC converter 18 further has a function as a buck converter. For example, when the first motor MG1 functions as a generator, the AC power from the first motor MG1 is converted into DC power by the first inverter 20, stepped down by the DC-DC converter 18, and then supplied to the battery 12. Similarly, when the second motor MG2 functions as a generator, the AC power from the second motor MG2 is converted into DC power by the second inverter 22, stepped down by the DC-DC converter 18, and then supplied to the battery 12.

[0023] As shown in Fig. 1, the power conversion device 14 further includes two smoothing capacitors 30 and 32. The two smoothing capacitors 30 and 32 include a first smoothing capacitor 30 and a second smoothing capacitor 32. The first smoothing capacitor 30 is provided between a pair of low voltage terminals 18a and 18b of the power conversion device 14. That is, the first smoothing capacitor 30 is connected between the positive low voltage terminal 18a and the negative low voltage terminal 18b. Thereby, the first smoothing capacitor 30 can suppress the ripple current generated on the low voltage terminals 18a and 18b sides when the two switching elements 26a and 26b are switched. Similarly, the second smoothing capacitor 32 is provided between a pair of high voltage terminals 18c and 18d of the power conversion device 14. That is, the second smoothing capacitor 32 is connected between the positive high voltage terminal 18c and the negative high voltage terminal 18d. Thereby, the second smoothing capacitor 32 can suppress the ripple current generated on the high voltage terminals 18c and 18d sides when the two switching elements 26a and 26b are switched. Note that the power supply system 10 does not necessarily need to include the two smoothing capacitors 30 and 32, and it may include at least one of the first smoothing capacitor 30 or the second smoothing capacitor 32.

[0024] As shown in Fig. 1, the power supply system 10 further includes two voltage sensors 34 and 36. The two voltage sensors 34 and 36 include a first voltage sensor 34 and a second voltage sensor 36. The first voltage sensor 34 is connected in parallel with the first smoothing capacitor 30 and can detect the voltage of the first smoothing capacitor 30. Similarly, the second voltage sensor 36 is connected in parallel with the second smoothing capacitor 32 and can detect the voltage of the second smoothing capacitor 32. Each voltage sensor 34 and 36 is communicably connected to the control device 16, and the detected voltage by each voltage sensor 34 and 36 is configured to be acquired by the control device 16. Note that the number of the voltage sensors 34 and 36 can be appropriately changed according to the number of the smoothing capacitors 30 and 32 for which the voltage is to be detected.

[0025] As shown in Figure 1, the power supply system 10 further comprises a first relay 38, a second relay 40, and a third relay 42. The first relay 38 is provided between the positive terminal of the battery 12 and the positive low-voltage terminal 18a of the DC-DC converter 18, and can electrically connect and disconnect them. The second relay 40 is provided between the negative terminal of the battery 12 and the negative low-voltage terminal 18b of the DC-DC converter 18, and can electrically connect and disconnect them. The third relay 42 is connected in parallel with the second relay 40 and in series with the resistive element 44. That is, the third relay 42 and the resistive element 44 are provided between the negative terminal of the battery 12 and the resistive element 44. Therefore, the third relay 42, like the second relay 40, can electrically connect and disconnect the negative terminal of the battery 12 and the negative low-voltage terminal 18b of the DC-DC converter 18.

[0026] In the above configuration, when the first relay 38 and the second relay 40 are turned on, the battery 12 and the two motors MG1 and MG2 are electrically connected via the power converter 14. Conversely, when the first relay 38 and the second relay 40 are turned off, the battery 12 and the power converter 14 are electrically disconnected, and the battery 12 and the two motors MG1 and MG2 are also electrically disconnected. Similarly, when the first relay 38 and the third relay 42 are turned on, the battery 12 and the two motors MG1 and MG2 are electrically connected via the power converter 14. Conversely, when the first relay 38 and the third relay 42 are turned off, the battery 12 and the power converter 14 are electrically disconnected, and the battery 12 and the two motors MG1 and MG2 are also electrically disconnected. The on and off states of the first relay 38, the second relay 40, and the third relay 42 are controlled by the control device 16. However, in other embodiments, the on and off states of each relay 38, 40, and 42 may be switched by another control device or by a user instead of the control device 16.

[0027] While not particularly limited, the power supply system 10 further includes a step-down converter 46, as shown in Figure 1. The step-down converter 46 is electrically connected between the battery 12 and the vehicle's auxiliary battery AB. The step-down converter 46 can step down the DC power from the battery 12 and supply it to the auxiliary battery AB. The auxiliary battery AB is connected to various control systems and other auxiliary equipment of the vehicle and supplies them with power. While not particularly limited, the rated voltage of the auxiliary battery AB is 12 volts.

[0028] Next, with reference to Figure 2-3, a series of startup processes performed by the control device 16 will be described. In this startup process, the battery 12 and the power converter 14 are electrically connected. The control device 16 starts the series of startup processes shown in Figure 2 in response to a predetermined startup operation by the user, such as turning on the ignition switch. As will be explained in more detail later, the counter value is reset to zero at the time the control device 16 starts the series of startup processes.

[0029] When a predetermined startup operation is performed by the user, the control device 16 executes a process to turn on the first relay 38 (step S10). Specifically, as shown in Figure 3, when the user turns on the ignition switch at time T1, the higher-level control device (not shown) starts outputting an IG signal and outputs an ST signal at time T2. The IG signal is a startup signal supplied to the vehicle's auxiliary equipment, and the auxiliary equipment starts up in accordance with the received IG signal. The ST signal is a startup signal supplied to the control device 16 of the power supply system 10, and the control device 16 starts the startup process in response to the receipt of the ST signal and executes the process to turn on the first relay 38 described above. If the first relay 38 is functioning correctly, the process in step S10 electrically connects the positive terminal of the battery 12 and the positive low-voltage terminal 18a of the DC-DC converter 18 via the first relay 38.

[0030] Next, the control device 16 performs the process of turning on the third relay 42 (step S12, time T3 in Figure 3). As a result, if the third relay 42 is functioning correctly, the negative terminal of the battery 12 and the negative low-voltage terminal 18b of the DC-DC converter 18 are electrically connected via the third relay 42. If the first relay 38 and the third relay 42 are functioning correctly, the processes in steps S10 and S12 result in an electrical connection between the battery 12 and the two motors MG1 and MG2 via the power converter 14.

[0031] Subsequently, the control device 16 monitors the voltage detected by the first voltage sensor 34 and performs a process to determine whether or not a predetermined change is detected in the detected voltage (step S14). Here, the predetermined change means that the detected voltage reaches a predetermined threshold voltage. The predetermined threshold voltage is determined, for example, according to the voltage of the battery 12, and can be the rated voltage of the battery 12 or the voltage actually output from the battery 12. In other embodiments, the predetermined change may be a predetermined range of change that appears in the detected voltage, or a predetermined rate of change that appears in the detected voltage, etc. Furthermore, in yet another embodiment, the control device 16 may monitor the voltage detected by the second voltage sensor 36 instead of the first voltage sensor 34. That is, the control device 16 only needs to perform the process in step S14 based on the voltage detected by either the first voltage sensor 34 or the second voltage sensor 36.

[0032] For example, when both the first relay 38 and the third relay 42 are functioning normally, the charging of the first smoothing capacitor 30 (and / or the second smoothing capacitor 32) starts as expected, and a predetermined change in the detected voltage is detected. In this case, the result in step S14 is YES. On the other hand, when there is a malfunction in at least one of the first relay 38 and the third relay 42, the charging of the first smoothing capacitor 30 (and / or the second smoothing capacitor 32) does not start, and therefore, a predetermined change in the detected voltage is not detected (see time T3 in Figure 3). In this case, the result in step S14 is NO. However, the malfunction occurring in at least one of the first relay 38 and the third relay 42 at this time includes temporary malfunctions such as freezing of the relay contacts.

[0033] If the answer in step S14 is NO, the control device 16 increments a predetermined counter value (step S16) and performs the process of turning off the first relay 38 and the third relay 42 (step S18, time T4 in Figure 3). As a result, the counter value increases by 1 and the battery 12 is electrically disconnected from the two motors MG1 and MG2.

[0034] If the counter value has not reached a predetermined upper limit (NO in step S20), the control device 16 returns to the process in step S10 in response to the user's restart operation (times T5 and T6 in Figure 3). As a result, as long as the response is NO in step S14 and NO in step S20, the processes from step S10 to step S20 are repeatedly executed. For example, the predetermined upper limit is 4. On the other hand, if the counter value reaches a predetermined upper limit (YES in step S20), the control device 16 determines that there is a malfunction in at least one of the first relay 38 or the third relay 42 (step S22). As a result, the control device 16 terminates the series of startup processes.

[0035] If the abnormality in at least one of the first relay 38 and the third relay 42 is a temporary abnormality such as the freezing of the relay contacts, it is assumed that the freezing will be resolved by the physical stimulation caused by the repeated on and off switching of each relay 38 and 42. That is, before the counter value reaches a predetermined upper limit, the first relay 38 and the third relay 42 are turned on normally, and a predetermined change in the detection voltage is detected (YES in step S14, time T7 in Figure 3). As a result, the startup process proceeds normally without determining that the relays 38 and 42 are abnormal. On the other hand, if the abnormality in at least one of the first relay 38 and the third relay 42 is not a temporary abnormality such as the freezing of the relay contacts, even if the relays 38 and 42 are repeatedly turned on and off, a predetermined change in the detection voltage is not detected (YES in step S20), and it is determined that the relays 38 and 42 are abnormal (step S22).

[0036] If the answer in step S14 is YES, the control device 16 resets the counter value (step S24). That is, the control device 16 sets the counter value to zero. As a result, the counter value is zero when the control device 16 starts the startup process. Therefore, the counter value represents the number of times the first relay 38 and the third relay 42 are turned on and off in each of the series of startup processes. However, in other embodiments, the process in step S24 may be executed after step S26 and / or step S28, which will be described later. In yet another embodiment, the process in step S24 may be executed before the process in step S16 in the series of startup processes is executed, for example, at the timing when the series of startup processes start or in the processes of steps S10-S14.

[0037] Next, the control device 16 performs the process of turning on the second relay 40 (step S26, time T8 in Figure 3). As a result, the negative terminal of the battery 12 and the negative low-voltage terminal 18b of the DC-DC converter 18 are electrically connected via the second relay 40. Then, the control device 16 performs the process of turning off the third relay 42 (step S28, time T9 in Figure 3). As a result, the state in which the negative terminal of the battery 12 and the negative low-voltage terminal 18b of the DC-DC converter 18 are electrically connected via both the second relay 40 and the third relay 42 changes to a state in which they are electrically connected via only the second relay 40. Note that the state in which the battery 12 and the two motors MG1 and MG2 are electrically connected via the power converter 14 is maintained.

[0038] The control device 16 determines whether the first relay 38 and the second relay 40 are properly energized (step S30). For this determination, for example, the control device 16 can monitor the excitation voltage or excitation current supplied to the first relay 38 and the second relay 40 to determine whether the excitation voltage or excitation current is being supplied correctly. If the result in step S30 is NO, the control device 16 determines that there is a problem with at least one of the first relay 38 and the second relay 40 (step S32) and terminates the series of startup processes. If the result in step S30 is YES, the control device 16 determines that the first relay 38 and the second relay 40 are normal and terminates the series of startup processes. If the result in step S30 is YES, as shown in Figure 3, the control device 16 transmits a Ready signal to a higher-level control device (not shown) at approximately the same time as time T9, indicating that the series of startup processes has been successfully completed.

[0039] In the power supply system 10 described above, for example, a startup process is initiated in response to a startup operation by the user. In this startup process, first, the first relay 38 and the third relay 42 are turned on, and then the voltage detected by the voltage sensors 34 and 36 is monitored. When each relay 38 and 42 is functioning normally, the charging of the first smoothing capacitor 30 (and / or the second smoothing capacitor 32) begins as expected, and a predetermined change in the detected voltage is detected. On the other hand, when there is a malfunction in at least one of the relays 38 and 42, the charging of the first smoothing capacitor 30 (and / or the second smoothing capacitor 32) does not begin, and therefore, a predetermined change in the detected voltage is not detected (see time T3 in Figure 3). However, the malfunctions occurring in the relays 38 and 42 at this time include temporary malfunctions such as freezing of the relay contacts. Therefore, at this stage, without determining that there is a malfunction in the relays 38 and 42, the counter value is incremented, and then the process of turning off the first relay 38 and the third relay 42 is executed. If the startup process is not completed, for example, the user can perform the startup operation again, which will cause the process of turning on the first relay 38 and the third relay 42 to be executed again. This process is repeated until the counter value reaches a predetermined upper limit, at which point the relays 38 and 42 are determined to be abnormal. At this time, if the abnormality in relays 38 and 42 is a temporary abnormality such as freezing of the relay contacts, it is assumed that the freezing will be resolved by the physical stimulation caused by the repeated turning on and off of each relay 38 and 42. That is, before the counter value reaches the predetermined upper limit, the first relay 38 and the third relay 42 are turned on normally, and a predetermined change in the detection voltage is detected (time T7 in Figure 3). As a result, the startup process proceeds normally without the relays 38 and 42 being determined to be abnormal. In this way, if freezing occurs on the contacts of at least one of the first relay 38 or the third relay 42, it is possible to avoid the relays 38 and 42 being determined to be abnormal. The system can accurately detect abnormalities in relays 38 and 42, thereby preventing unnecessary replacement of components.

[0040] Although several specific examples have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or in the drawings exhibit technical usefulness individually or in combination. [Explanation of Symbols]

[0041] 10: Power System 12: Battery 14: Power converter 16: Control device 18: DC-DC converter 18a: Positive low-voltage terminal 18b: Negative low-voltage terminal 18c: Positive high-voltage terminal 18d: Negative high-voltage terminal 20: First Inverter 22: Second Inverter 24: Reactor 26a, 26b: Switching elements 28a, 28b: Diode element 30: First smoothing capacitor 32: Second smoothing capacitor 34: First voltage sensor 36: Second voltage sensor 38: 1st Relay 40: 2nd Relay 42: Third Relay 44: Resistor element 46: Step-down converter AB: Auxiliary battery MG1: First motor MG2: Second motor

Claims

1. A vehicle power supply system that supplies power to the vehicle's load, Battery and A power conversion device having a smoothing capacitor is connected between the battery and the load, A voltage sensor for detecting the voltage of the smoothing capacitor, A first relay is provided between the positive terminal of the battery and the power converter, A second relay is provided between the negative terminal of the battery and the power converter, A third relay is connected in parallel with the second relay and in series with a resistive element, A control device connected to the voltage sensor and controlling the on / off states of the first relay, the second relay, and the third relay to perform a startup process that electrically connects the battery and the power converter, Equipped with, The aforementioned startup process is: A first process that turns on the first relay and the third relay, A second process is performed after the first process, in which the voltage detected by the voltage sensor is monitored and a predetermined change appearing in the detected voltage is detected. If the predetermined change is not detected, a third process is performed in which a predetermined counter value is incremented and the first relay and the third relay are turned off. If the counter value has not reached a predetermined upper limit after the third process, the process returns to the first process, and when the counter value reaches the predetermined upper limit, a fourth process is performed in which it is determined that an abnormality has occurred in at least one of the first relay or the third relay, and the startup process is terminated. A vehicle power system, including a vehicle power supply system.

2. The power supply system for a vehicle according to claim 1, wherein the second process detects that the detected voltage reaches a predetermined threshold voltage as the predetermined change appearing in the detected voltage.

3. The vehicle power supply system according to claim 2, wherein the threshold voltage is determined according to the voltage of the battery.

4. The power supply system for a vehicle according to any one of claims 1 to 3, wherein the startup process is executed from the first process in response to a startup operation by the user, and after the first relay and the third relay are turned off in the third process, the process is restarted from the first process in response to another startup operation by the user.

5. The vehicle power supply system according to any one of claims 1 to 3, wherein the startup process further includes a fifth process of turning on the second relay and turning off the third relay when the predetermined change is detected in the second process.

6. The power supply system for a vehicle according to claim 5, wherein the fifth process further includes a process for resetting the counter value.

7. The vehicle power supply system according to any one of claims 1 to 3, wherein the power conversion device includes at least one of a boost converter for boosting the power supplied from the battery and an inverter for converting the DC power supplied from the battery into AC power.

8. The power conversion device includes at least the boost converter, The vehicle power supply system according to claim 7, wherein the smoothing capacitor is located either between the battery and the boost converter, or between the boost converter and the load.

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