Power supply device

Abstract

A common input unit capacitor (553) has a high-potential-side electrode connected to a power supply line (Lp) that is connected between a plurality of systems on the power converter (601, 602) side as compared to reverse connection protection relays (521, 522) of the systems. At initial check, a boost circuit (20) performs over-boost processing for temporarily raising a target voltage above a value at normal operation. A pre-charge circuit (30) applies the boosted voltage (VS) resulting from the over-boost processing to the high-potential-side electrode of the common input unit capacitor (553). A monitoring circuit (40) detects, one by one for the reverse connection protection relays (521, 522) of the systems, an OFF-state sticking abnormality according to a post-relay voltage (Vry) which is the voltage on the inverter side of the reverse connection protection relays.

Description

power supply device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-129856, filed on August 6, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a power supply device.

[0003] Conventionally, a power supply device that converts DC power from a battery using a power converter such as an inverter and supplies it to a load such as a three-phase motor has been known to include a reverse polarity protection relay in the power line between the battery and the power converter. Also, a technology for detecting stuck-ON and stuck-OFF abnormalities of the reverse polarity protection relay during an initial check has been known. For example, the power supply device disclosed in Patent Document 1 performs overvoltage boosting using a boost circuit in a configuration that does not include a power relay on the battery side of the reverse polarity protection relay in the power line. In the overvoltage boosting process, for example, a battery voltage of approximately 12 V is boosted to approximately 22 V and precharged to an input capacitor. This allows for the detection of stuck-ON and stuck-OFF abnormalities of the reverse polarity protection relay during an initial check.

[0004] Japanese Patent Application Laid-Open No. 2023-53563

[0005] In a multi-system power supply device in which multiple power converters are provided redundantly, a reverse connection protection relay is connected to the power line from the battery to the power converter of each system, but a power supply relay is not provided. If the set of the reverse connection protection relay, input capacitor, and power converter is separated and independent for each system, it is possible to detect ON-fixed abnormalities and OFF-fixed abnormalities of the reverse connection protection relay by performing the abnormality detection method of Patent Document 1 for each system.

[0006] On the other hand, a circuit configuration is assumed in which power supply lines are connected to each other between multiple systems on the power converter side of the reverse polarity protection relay of each system, and the high-potential side electrode of an input capacitor common to the multiple systems is connected to the power supply line.Patent Document 1 does not mention at all whether or not a method for detecting an abnormality in a reverse polarity protection relay can be applied to this circuit configuration.

[0007] An object of the present disclosure is to provide a power supply device that does not have a power supply relay on the power line, and that has multiple systems in which the power lines are connected to each other on the power converter side of the reverse connection protection relay of each system, and that properly performs an initial check of the reverse connection protection relay.

[0008] The power supply device according to the present disclosure is a multi-system power supply device that converts DC power from a battery using multiple power converters redundantly provided between a power supply line connected to a battery and a ground line and supplies the converted power to a load. This power supply device includes multiple power converters, multiple reverse connection protection relays, a common input capacitor, a boost circuit, a precharge circuit, and a monitoring circuit.

[0009] The reverse polarity protection relay is provided in the power supply line between the battery and the power converter of each system. A diode that conducts current from the battery to the power converter is connected in parallel to the reverse polarity protection relay, and when the relay is turned off, it cuts off current from the power converter to the battery. The common input capacitor has a high-potential electrode connected to the power supply line connected to each other between the multiple systems on the power converter side of each system's reverse polarity protection relay, and a low-potential electrode connected to the ground line.

[0010] The boost circuit boosts the input voltage supplied from the battery to a target voltage. The precharge circuit precharges the common input capacitor by applying the boosted voltage output by the boost circuit to the high-potential electrode. The monitoring circuit detects a stuck-off abnormality in the reverse polarity protection relay of each system during an initial check of the power supply device. This power supply device does not have a power relay in the power line between the battery and the reverse polarity protection relay of each system that cuts off current from the battery side to the power converter side when turned off.

[0011] During the initial check, the boost circuit performs an overboost process to temporarily raise the target voltage above the value during normal operation. The precharge circuit applies the boosted voltage generated by the overboost process to the high-potential electrode of the common input capacitor.

[0012] The monitoring circuit detects a stuck-off abnormality for each reverse connection protection relay in turn, one by one, in accordance with the post-relay voltage, which is the voltage on the inverter side of the reverse connection protection relay.

[0013] In the power supply device of the present disclosure, after performing the overvoltage process, the monitoring circuit can sequentially detect the reverse connection protection relays of each system one by one as a stuck-on abnormality. Note that, regarding the stuck-on abnormality, it can detect that one or more of the reverse connection protection relays are stuck-on abnormal.

[0014] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a circuit diagram of a dual-system power supply device according to one embodiment, Fig. 2 is a schematic circuit diagram of a dual-system power supply device according to one embodiment, which is a simplified version of Fig. 1, Fig. 3 is a schematic circuit diagram of a reference configuration example 1 of the dual-system power supply device, Fig. 4 is a schematic circuit diagram of a reference configuration example 2 of the dual-system power supply device, Fig. 5 is a diagram illustrating an initial check flow under normal conditions when the reverse connection protection relays of each system are turned on one by one according to the operating method of this embodiment, and Fig. 6 is a diagram illustrating a flow of a check of the reverse connection protection relays of one or more systems when the reverse connection protection relays of one or more systems are turned on one by one according to the operating method of this embodiment. 7 is a diagram for explaining detection of an ON stuck abnormality of a relay, FIG. 7 is a diagram for explaining detection of an OFF stuck abnormality of a first system reverse connection protection relay, FIG. 8 is a diagram for explaining detection of an OFF stuck abnormality of a second system reverse connection protection relay, FIG. 9 is a diagram for explaining inability to detect an OFF stuck abnormality of one system when two systems of reverse connection protection relays are simultaneously turned ON by an operating method of the comparative example, and FIG. 10 is a matrix showing whether or not an abnormality can be detected in two systems of reverse connection protection relays by the operating methods of the comparative example and this embodiment.

[0015] A power supply device according to one embodiment will be described with reference to the drawings. The power supply device of this embodiment converts DC power from a battery in an electric power steering device and supplies it to a steering assist motor as a "load." The steering assist motor is configured as a three-phase brushless motor having multiple (e.g., two) three-phase winding sets.

[0016] Specifically, the ECU of the electric power steering device and an inverter acting as a "power converter" work together to function as a power supply device. The ECU is composed of a microcomputer, a pre-driver, etc., and is equipped with a CPU, ROM, RAM, I / O, and bus lines connecting these components (not shown). The ECU performs control by software processing, in which the CPU executes pre-stored programs, and hardware processing, in which a dedicated electronic circuit is used.

[0017] An ECU of an electric power steering device generally starts (i.e., starts driving) when the vehicle's ignition signal is turned on, and stops driving when the ignition signal is turned off. Hereinafter, operation after the initial check is referred to as normal operation. The motor control configuration during normal operation, performed by a control unit (not shown), is the same as that of a general motor control device. In this embodiment, attention is particularly focused on the initial check when the ECU is started up.

[0018] (One embodiment) Figure 1 shows the circuit configuration of one embodiment. The power supply device 10 of this embodiment is a dual-system power supply device in which two inverters 601, 602 are provided redundantly as "plural power converters." The motor 80, which serves as the "load," is a double-winding motor having two three-phase winding sets 801, 802. The wiring configuration of the motor 80 is not limited to a Y connection, and may be a Delta connection.

[0019] The power supply device 10 includes two inverters 601, 602, two reverse connection protection relays 521, 522, a common input capacitor 553, a boost circuit 20, a precharge circuit 30, a monitoring circuit 40, etc. Elements of the first system in the two-system redundant configuration are designated with a "1" in the third digit of the code, and elements of the second system are designated with a "2" in the third digit of the code.

[0020] The two inverters 601, 602 are redundantly provided between a power supply line Lp connected to the battery 15 and a ground line Lg. The first system inverter 601 includes three-phase upper and lower arm switching elements 611-661. The second system inverter 602 includes three-phase upper and lower arm switching elements 612-662. Here, the notation "61*-66* (*=1, 2)" means "61*, 62*, 63*, 64*, 65*, 66*."

[0021] In this embodiment, MOSFETs are used as the switching elements 611-661 and 612-662 of the inverters 601 and 602. When the switching elements 611-661 and 612-662 are operated, the inverters 601 and 602 convert the DC power of the battery 15 into three-phase AC power and supply it to the three-phase winding sets 801 and 802.

[0022] The reverse connection protection relays 521, 522 are provided on the power supply line Lp between the battery 15 and the inverters 601, 602 of each system. A return diode that conducts current from the battery 15 side to the inverters 601, 602 side is connected in parallel to the reverse connection protection relays 521, 522. In this embodiment, a parasitic diode of the MOSFET that constitutes the reverse connection protection relays 521, 522 conducts current from the battery 15 side to the inverters 601, 602 side. When turned off, the reverse connection protection relays 521, 522 cut off the current from the inverters 601, 602 side to the battery 15 side. The voltage drop due to the parasitic diode is referred to as Vf. Hereinafter, "rear side of the reverse connection protection relay" means "the inverter side of the reverse connection protection relay."

[0023] 1, i.e., the power supply line Lp between the battery 15 and the reverse connection protection relays 521 and 522 of each system. This "power supply relay" cuts off the current from the battery 15 side to the inverters 601 and 602 side when it is turned off.

[0024] The common input capacitor 553 is a capacitor provided in common to the input sections of the first-system inverter 601 and the second-system inverter 602, and is a configuration unique to this embodiment. The high-potential side electrode of the common input capacitor 553 is connected to the power supply line Lp that connects the two systems to each other behind the reverse connection protection relays 521 and 522. The low-potential side electrode of the common input capacitor 553 is connected to the ground line Lg.

[0025] That is, the inverter 601 side of the first system reverse connection protection relay 521 and the inverter 602 side of the second system reverse connection protection relay 522 on the power supply line Lp are connected to each other. Fig. 1 shows a common capacitor line Lcc that connects the power supply lines Lp to each other on the inverter 601, 602 side of the reverse connection protection relays 521, 522, and shows a wiring configuration in which the high-potential side electrode of the common input section capacitor 553 is connected to the common capacitor line Lcc. However, the actual wiring layout only needs to be electrically equivalent to the wiring configuration shown in Fig. 1, and the common capacitor line Lcc does not need to be apparent.

[0026] During normal operation, common input capacitor 553 smoothes the input voltage supplied from battery 15 and also suppresses transmission of switching noise from inverters 601 and 602 to the outside. In a typical two-system configuration, input capacitors 551 and 552 are provided for each system, as shown by the dashed lines in Figure 1. In contrast, by providing common input capacitor 553 that can be shared by the two systems, the total capacitor capacity of the two systems can be reduced, and the mounting space on the board can be reduced, resulting in a more compact product and lower costs.

[0027] Depending on the board layout, arranging three relatively small capacitors side by side may result in a more compact overall design than mounting one relatively large capacitor. In such a case, for example, a total of three capacitors, namely, input capacitors 551 and 552 for each system and common input capacitor 553, may be used in combination.

[0028] The boost circuit 20 boosts the input voltage (e.g., approximately 12 V) supplied from the battery 15 to a target voltage. For example, the boost circuit 20 is configured as a chopper-type boost circuit. The boost voltage VS output by the boost circuit 20 is output to the precharge circuit 30 as well as to the upper arm elements 611-631, 612-632 of the inverters 601, 602 and driver circuits such as motor relays (not shown). Here, the voltage on the battery 15 side of the reverse connection protection relays 521, 522 is referred to as the "battery voltage Vb." Furthermore, the voltage on the inverter 601, 602 side of the reverse connection protection relays 521, 522 of each system is referred to as the "post-relay voltage Vry."

[0029] In a circuit configuration without a power relay, it is not possible to monitor the voltage between the power relay and the reverse polarity protection relay during an initial check. Furthermore, if the difference between the battery voltage Vb and the relay post-voltage Vry is small, a detection error or other factor may cause an error in distinguishing between normal operation and a stuck abnormality, making it difficult to detect an abnormality in the reverse polarity protection relays 521 and 522. Therefore, during an initial check, the boost circuit 20 performs an "overboost process" that temporarily increases the target voltage above the value during normal operation. For example, an input voltage of approximately 12 V is boosted to approximately 16 V during normal operation, whereas the overboost process boosts the voltage to approximately 22 V.

[0030] The precharge circuit 30 precharges the common input capacitor 553 by applying the boosted voltage VS output by the boost circuit 20 to the high potential electrode of the common input capacitor 553. In Fig. 1, the output terminal of the precharge circuit 30 is connected to the common capacitor line Lcc. During an initial check, the voltage applied from the precharge circuit 30 to the high potential electrode of the common input capacitor 553 becomes the post-relay voltage Vry.

[0031] At this time, if both reverse connection protection relays 521, 522 are in the cut-off state, the post-relay voltage Vry is maintained. Also, if one or both of reverse connection protection relays 521, 522 are in the conductive state, the current discharged from common input capacitor 553 flows to battery 15, causing the post-relay voltage Vry to decrease. During the initial check, monitoring circuit 40 detects a stuck-ON abnormality and a stuck-OFF abnormality of reverse connection protection relays 521, 522 of each system according to the post-relay voltage Vry.

[0032] FIG. 2 is a simplified schematic circuit diagram of inverters ("INV" in the figure) 601, 602, etc. in FIG. 1 . The ground line Lg is indicated by a ground symbol. Based on the format of FIG. 2 , FIGS. 3 and 4 show two reference configuration examples of a dual-system power supply device. In reference configuration example 1 shown in FIG. 3 , the power supply line Lp branches into two at the rear of one reverse connection protection relay 52 and is connected to a first-system inverter 601 and a second-system inverter 602. A common input capacitor 553 is also provided in common to the two inverters 601, 602. With this configuration, it is possible to detect a stuck-ON abnormality and a stuck-OFF abnormality of the reverse connection protection relay 52 using conventional technology during an initial check.

[0033] In the reference configuration example 2 shown in Figure 4, the power supply line Lp branches into two between the battery 15 and the two systems of reverse connection protection relays 521, 522. Furthermore, input capacitors 551, 552 are provided in the inverters 601, 602 of each system. In other words, a set of a reverse connection protection relay, an input capacitor, and an inverter is provided separately and independently for each system. In this configuration, using conventional technology during an initial check, it is possible to detect ON-fixed abnormalities and OFF-fixed abnormalities of the reverse connection protection relays 521, 522 for each system.

[0034] Unlike these reference configuration examples 1 and 2, in the circuit configuration of this embodiment shown in Figures 1 and 2, a common input capacitor 553 is provided in the power supply line Lp connected between the two systems behind the two systems of reverse connection protection relays 521 and 522. As will be described in detail later, with this circuit configuration, even if a conventional abnormality detection method is used, there are cases where a stuck-OFF abnormality in one of the systems cannot be detected.

[0035] Therefore, in this embodiment, an object is to properly perform an initial check of the reverse connection protection relays 521, 522 of each system using a new operation method (i.e., a method of switching between relay ON operation and OFF operation) that differs from conventional technology in the circuit configuration shown in Figures 1 and 2. Next, detection of ON-fixed abnormality and OFF-fixed abnormality of the reverse connection protection relays 521, 522 according to this embodiment will be described in detail with reference to Figures 5 to 8.

[0036] The monitoring circuit 40 detects a stuck-off abnormality by sequentially turning on the reverse connection protection relays 521 and 522 of each system. In the example shown in FIGS. 5 to 8 , the first system reverse connection protection relay 521 and the second system reverse connection protection relay 522 are sequentially turned on to detect a stuck-off abnormality. Conversely, the second system reverse connection protection relay 522 and the first system reverse connection protection relay 521 may be sequentially turned on. Furthermore, the period from when the boost circuit 20 finishes overboosting processing for one detection target relay until it starts overboosting processing for the next detection target relay is defined as an "overboosting interval."

[0037] One reverse connection protection relay that is the target of detection for a stuck-OFF abnormality by the monitoring circuit 40 is referred to as a "detection target relay," and reverse connection protection relays other than the detection target relay are referred to as "non-detection target relays." In the examples of FIGS. 5 to 8 , in the first detection of a stuck-OFF abnormality, the first system reverse connection protection relay 521 corresponds to the detection target relay, and the second system reverse connection protection relay 522 corresponds to the non-detection target relay. In the second detection of a stuck-OFF abnormality, the second system reverse connection protection relay 522 corresponds to the detection target relay, and the first system reverse connection protection relay 521 corresponds to the non-detection target relay.

[0038] 5 to 8 show, from the top to the bottom, the ON / OFF of the ignition switch ("IG" in the figures), the boost voltage VS and the post-relay voltage Vry, the potential difference ΔV before and after the relay, the ON / OFF of the precharge, the ON / OFF of the first system reverse connection protection relay 521, and the ON / OFF of the second system reverse connection protection relay 522. The potential difference ΔV before and after the relay is defined as the potential difference (ΔV = Vry - Vb) obtained by subtracting the battery voltage Vb from the post-relay voltage Vry, and corresponds to the potential difference across the reverse connection protection relays 521 and 522.

[0039] 5 to 8 are common to all but the voltage after the relay Vry and the potential difference before and after the relay ΔV. Fig. 5 shows the behavior of the voltage after the relay Vry and the potential difference before and after the relay when normal, Fig. 6 shows the behavior when one or more reverse connection protection relays are stuck on abnormally, Fig. 7 shows the behavior when the first system reverse connection protection relay 521 is stuck off abnormally, and Fig. 8 shows the behavior when the second system reverse connection protection relay 522 is stuck off abnormally. Before starting up the power supply device 10, the ignition switch is OFF, precharging by the precharge circuit 30 is ON, and the reverse connection protection relays 521 and 522 are OFF.

[0040] First, the boost voltage VS indicated by the two-dot chain line in each figure will be described. For example, let us assume that the battery voltage is 12 V, the boost voltage VS during normal operation is 16 V, and the boost voltage VS resulting from the overboost process is 22 V. When the ignition switch is turned on at time t0, the boost voltage VS rises from 12 V to 16 V. Thereafter, between time ts1 and time te1, the boost circuit 20 performs a first overboost process, and the boost voltage VS temporarily rises to 22 V. When the first overboost process ends at time te1, the boost voltage VS returns to the normal operating voltage of 16 V.

[0041] During the voltage boost waiting time after time t0, an initial check may be performed on other elements of the power supply device 10. The other elements include, for example, the switching elements 611-661 and 612-662 that constitute the inverters 601 and 602. In addition, an initial check may be performed on a motor relay, a current sensor, a rotation angle sensor, and the like that are not shown in FIG.

[0042] When the first overvoltage boost process is completed at time te1, the first-system reverse connection protection relay 521 is turned on from the OFF state. The period from time ts1 to time te1 is the stuck-on detection timing. Thereafter, the period from time te1 to time ts2 is the "first-system stuck-off detection timing" in which the first-system reverse connection protection relay 521 is the detection target relay. At time ts2, the first-system reverse connection protection relay 521 is turned off. Subsequently, from time ts2 to time te2, the boost circuit 20 performs a second overvoltage boost process. After the second overvoltage boost process, the period from time te2 to time tz is the "second-system stuck-off detection timing" in which the second-system reverse connection protection relay 522 is the detection target relay.

[0043] The precharge circuit 30 may continue precharging the common input capacitor 553 in an ON state during the overboost interval from time te1 to time ts2, as shown by the solid line. This suppresses voltage drops during abnormality detection and shortens the boost time in the overboost process after the overboost interval. Alternatively, the precharge circuit 30 may temporarily turn off precharging the common input capacitor 553 from time te1 to time ts2, as shown by the dashed line.

[0044] 5, under normal conditions, before time ts1, reverse connection protection relays 521 and 522 are OFF, and current flows from battery 15 to inverters 601 and 602 only through the parasitic diodes. If the boosted voltage VS during the period from time to to time ts1 is ignored, the relay post-voltage Vry is calculated as (Vb-Vf), which is the battery voltage Vb minus the parasitic diode voltage drop Vf (approximately 1 V). At this time, the relay post-voltage difference ΔV is calculated as (-Vf), which is the parasitic diode voltage drop Vf minus 0 V.

[0045] After time ts1, under normal conditions, the relay post-voltage Vry follows the rise in the boosted voltage VS with a delay, eventually rising to the maximum voltage (≈VS - Vf). Accordingly, the relay post-voltage difference ΔV increases beyond 0 [V] to a maximum positive value. However, as shown in FIG. 6 , if one or more of the reverse connection protection relays 521, 522 (i.e., one or both) are stuck-on, the relay post-voltage Vry is not maintained and always becomes a value equivalent to the battery voltage Vb. Furthermore, the relay post-voltage difference ΔV always becomes 0 [V].

[0046] When the first overvoltage boost process ends at time te1, under normal conditions, the discharge of the common input capacitor 553 causes the relay post-voltage Vry to decrease. Furthermore, because the first system reverse connection protection relay 521 is turned on, the relay post-voltage Vry gradually converges toward the battery voltage Vb. Accordingly, the relay pre- and post-voltage difference ΔV decreases toward 0 V. However, as shown in FIG. 7 , if the first system reverse connection protection relay 521 is stuck-off abnormal, the relay post-voltage Vry does not decrease from the maximum voltage due to the overvoltage boost process. Furthermore, the relay pre- and post-voltage difference ΔV does not decrease from its maximum value.

[0047] Similarly, when the second overvoltage boosting process ends at time te2, in a normal state, the relay post-voltage Vry decreases and gradually converges toward the battery voltage Vb. Accordingly, the relay pre-potential difference ΔV decreases toward 0 V. However, as shown in FIG. 8 , in the case where the second system reverse connection protection relay 522 is in a stuck-off abnormality, the relay post-voltage Vry does not decrease from the maximum voltage due to the overvoltage boosting process. Furthermore, the relay pre-potential difference ΔV does not decrease from its maximum value.

[0048] Based on the above behavior, the monitoring circuit 40 can perform two types of stuck abnormality detection methods: [Detection Method 1] based on the relay post voltage Vry, and [Detection Method 2] based on the relay pre- and post-potential difference ΔV. The ON stuck abnormality detection method is the same as the conventional technique.

[0049] [Detection Method 1] In detection method 1, the voltage threshold Vth is set to a value (e.g., approximately 18 V) slightly higher than 16 V, which is the boost voltage VS during normal operation. Then, when the reverse connection protection relays 521 and 522 are normal, a predetermined boost time TA is set based on the time it takes for the relay post-voltage Vry to boost up to the voltage threshold Vth after time ts1. Furthermore, a predetermined drop time TD is set based on the time it takes for the relay post-voltage Vry to drop down to the voltage threshold Vth after times te1 and te2. The boost time TA and drop time TD are set taking into account detection errors and variations.

[0050] At the timing of stuck-ON detection, if the relay post-voltage Vry after the voltage rise time TA from time ts1 is equal to or greater than the voltage threshold Vth, it is determined to be normal, as shown in Fig. 5. If the relay post-voltage Vry after the voltage rise time TA from time ts1 is smaller than the voltage threshold Vth, it is determined to be stuck-ON abnormality in one or more of the reverse connection protection relays 521, 522, as shown in Fig. 6.

[0051] At the timing of detecting the stuck-off state of the first system, if the post-relay voltage Vry after the step-down time TD from time te1 is equal to or less than the voltage threshold value Vth, the first system reverse connection protection relay 521 is determined to be normal, as shown in Fig. 5. If the post-relay voltage Vry after the step-down time TD from time te1 is greater than the voltage threshold value Vth, the first system reverse connection protection relay 521 is determined to be stuck-off abnormal, as shown in Fig. 7.

[0052] At the second system stuck-off detection timing, if the post-relay voltage Vry after the step-down time TD from time te2 is equal to or less than the voltage threshold Vth, the second system reverse connection protection relay 522 is determined to be normal, as shown in Fig. 5. If the post-relay voltage Vry after the step-down time TD from time te2 is greater than the voltage threshold Vth, as shown in Fig. 8, the second system reverse connection protection relay 522 is determined to be stuck-off abnormal.

[0053] In this way, in detection method 1, the monitoring circuit 40 performs the overvoltage boost process with all of the reverse connection protection relays 521, 522 turned OFF, and detects a stuck-ON abnormality in one or more of the reverse connection protection relays 521, 522 based on the potential difference ΔV across the relay after a predetermined boost time TA has elapsed from time ts1. The monitoring circuit 40 then turns on the relay to be detected with the relays not to be detected turned OFF, and detects a stuck-OFF abnormality in the relay to be detected based on the voltage Vry after the predetermined voltage drop time TD has elapsed from times te1, te2 when the application of the boosted voltage VS by the overvoltage boost process ended.

[0054] [Detection Method 2] In detection method 2, the potential difference threshold ΔVth is set to a value slightly greater than 0 V, which indicates that both ends of the reverse connection protection relays 521, 522 are at the same potential. Then, when the reverse connection protection relays 521, 522 are normal, a predetermined potential difference increase time Taa is set based on the time it takes for the potential difference ΔV across the relay to increase to the potential difference threshold ΔVth after time ts1. Furthermore, a predetermined potential difference reduction time Tdd is set based on the time it takes for the potential difference ΔV across the relay to decrease to the potential difference threshold ΔVth after times te1 and te2. The potential difference increase time Taa and the potential difference reduction time Tdd are set taking into account detection errors and variations.

[0055] At the stuck-ON detection timing, if the potential difference ΔV across the relay after the potential difference amplification time Taa from time ts1 is equal to or greater than the potential difference threshold ΔVth, the relay is determined to be normal, as shown in Fig. 5. If the potential difference ΔV across the relay after the potential difference amplification time Taa from time ts1 is smaller than the potential difference threshold ΔVth, the reverse connection protection relays 521, 522 are determined to be stuck-ON abnormal, as shown in Fig. 6.

[0056] At the first system stuck-off detection timing, if the potential difference ΔV across the relay after the potential difference reduction time Tdd has elapsed from time te1 is equal to or less than the potential difference threshold ΔVth, the first system reverse-connection protection relay 521 is determined to be normal, as shown in Fig. 5. If the potential difference ΔV across the relay after the potential difference reduction time Tdd has elapsed from time te1 is greater than the potential difference threshold ΔVth, the first system reverse-connection protection relay 521 is determined to be stuck-off abnormal, as shown in Fig. 7.

[0057] At the second system stuck-off detection timing, if the potential difference ΔV across the relay after the potential difference reduction time Tdd has elapsed from time te2 is equal to or less than the potential difference threshold ΔVth, the second system reverse-connection protection relay 522 is determined to be normal, as shown in Fig. 5. If the potential difference ΔV across the relay after the potential difference reduction time Tdd has elapsed from time te2 is greater than the potential difference threshold ΔVth, the second system reverse-connection protection relay 522 is determined to be stuck-off abnormal, as shown in Fig. 8.

[0058] In this way, in detection method 2, the monitoring circuit 40 performs the overvoltage processing with all of the reverse connection protection relays 521, 522 turned OFF, and detects a stuck-ON abnormality in one or more of the reverse connection protection relays 521, 522 based on the potential difference ΔV across the relay after a predetermined potential difference increase time Taa has elapsed since time ts1. The monitoring circuit 40 then turns on the relay to be detected with the relays not to be detected turned OFF, and detects a stuck-OFF abnormality in the relay to be detected based on the potential difference ΔV across the relay after a predetermined potential difference decrease time Tdd has elapsed since times te1, te2 when the application of the boosted voltage VS by the overvoltage processing ended.

[0059] (Comparison with Comparative Example) In the operation method of this embodiment, the two reverse connection protection relays 521, 522 are turned ON one by one in sequence. In contrast, the operation method of the comparative example is a method of simultaneously turning ON the two reverse connection protection relays 521, 522, which is an operation method that is simply assumed when applying conventional technology to a dual-system power supply device. Figure 9 shows changes in the post-relay voltage Vry and the potential difference ΔV before and after the relay when the operation method of the comparative example is performed after overvoltage processing.

[0060] When the overvoltage processing ends at time te1, the first system reverse connection protection relay 521 and the second system reverse connection protection relay 522 are simultaneously switched on from their OFF states. If both reverse connection protection relays 521 and 522 of both systems are stuck-off, the relay post-voltage Vry does not drop from the maximum voltage due to the overvoltage processing. Furthermore, the relay post-voltage difference ΔV also does not drop from its maximum value. Therefore, the monitoring circuit 40 can detect the stuck-off abnormality of both systems.

[0061] However, if one of the first system reverse connection protection relay 521 and the second system reverse connection protection relay 522 is stuck OFF and the other is normal, current flows from the high potential side electrode of the common input section capacitor 553 to the battery 15 via the normal reverse connection protection relay. Since the post-relay voltage Vry and the potential difference ΔV before and after the relay behave the same as in the normal state, the monitoring circuit 40 cannot detect the stuck OFF abnormality of one of the systems.

[0062] FIG. 10 shows in matrix form whether or not abnormalities can be detected for the two-system reverse connection protection relays according to the operation methods of the comparative example and this embodiment. There are nine possible patterns for the reverse connection protection relays 521 and 522 of each system, combining three modes: "normal," "fixed ON abnormality," and "fixed OFF abnormality." Of these, three patterns are the same when the two-system reverse connection protection relays 521 and 522 are swapped, resulting in a total of six possible cases. Furthermore, when both systems are normal, this is not subject to abnormality detection and is excluded. Hereinafter, the combination of each mode for the two-system reverse connection protection relays 521 and 522 will be expressed as "normal x fixed ON abnormality."

[0063] In both the operation methods of the comparative example and this embodiment, in the case of "normal × ON stuck abnormality" or "ON stuck abnormality × ON stuck abnormality," an abnormality can be detected as shown in FIG. 6 . However, it is not possible to identify which reverse connection protection relay is abnormal. In the case of "ON stuck abnormality × OFF stuck abnormality," an ON stuck abnormality can be detected, but an OFF stuck abnormality cannot be detected. Furthermore, in the case of "OFF stuck abnormality × OFF stuck abnormality," an abnormality can be detected by both the operation methods of the comparative example (see FIG. 9 ) and this embodiment.

[0064] The difference between the operation methods of the comparative example and the present embodiment in the ability to detect an abnormality is the case of "normal × stuck-off abnormality." As described above with reference to FIG. 9 , the operation method of the comparative example in which the two reverse connection protection relays 521, 522 are simultaneously turned on cannot detect a stuck-off abnormality. In contrast, in the present embodiment, by sequentially turning on the detection target relays of the two reverse connection protection relays 521, 522 one by one, it is possible to detect a stuck-off abnormality of the detection target relay even when the non-detection target relay is normal. Therefore, an initial check of the reverse connection protection relays 521, 522 of each system can be properly performed.

[0065] (Other Embodiments) (a) The present disclosure is not limited to two systems and can be similarly applied to a power supply device with three or more systems. Generally, if the number of systems is represented by N (N≧2), a power supply device with N systems has N inverters redundantly provided between a power supply line Lp and a ground line Lg, and N reverse connection protection relays are provided on the power supply line Lp between the battery 15 and each inverter. The high-potential side electrode of the common input capacitor 553 is connected to the power supply line Lp connected to each other among the N systems, on the inverter side of the reverse connection protection relay of each system.

[0066] In the initial checks of Figures 5 to 8, overvoltage processing is performed N times on the reverse connection protection relays of the first to Nth systems. The monitoring circuit detects a stuck-OFF abnormality for each reverse connection protection relay in each system, one by one. In each overvoltage processing, (N-1) reverse connection protection relays other than the detection target relay are defined as non-detection target relays. The monitoring circuit performs overvoltage processing with all reverse connection protection relays turned OFF, and then turns on the detection target relay with the (N-1) non-detection target relays turned OFF.

[0067] The precharge circuit may maintain the precharge ON state during at least one of the (N-1) overboost intervals. Preferably, the precharge circuit may maintain the precharge ON state during all of the (N-1) overboost intervals. This can suppress a voltage drop during abnormality detection and shorten the boost time in the overboost process after the overboost interval.

[0068] (b) As shown in Figure 5, in the initial check of the above embodiment, the monitoring circuit 40 detects an ON-fixed abnormality in all reverse connection protection relays during the initial overvoltage processing, and then detects an OFF-fixed abnormality in the reverse connection protection relays of each system in a series of steps. However, in the present disclosure, the procedure for detecting an ON-fixed abnormality is not important. For example, if it is known that there is no ON-fixed abnormality before this initial check, the monitoring circuit 40 does not need to detect an ON-fixed abnormality immediately before detecting an OFF-fixed abnormality.

[0069] (c) The load of the power supply device 10 is not limited to the three-phase motor 80, but may be a single-phase motor or a multi-phase motor other than three-phase, or may be an actuator other than a motor or other load. An H-bridge circuit or the like may be used as the "power converter" instead of a multi-phase inverter. The reverse connection protection relays 521, 522 and other switching elements are not limited to MOSFETs, but may be composed of other types of transistors, etc.

[0070] As described above, the present disclosure is not limited to the above-described embodiments, and can be embodied in various forms without departing from the spirit of the present disclosure.

[0071] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0072] The present disclosure has been described based on the embodiments. However, the present disclosure is not limited to the embodiments and structures. The present disclosure also encompasses various modifications and variations within the scope of equivalents. Furthermore, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A power supply device of multiple systems that converts DC power of a battery by multiple power converters (601, 602) redundantly provided between a power supply line (Lp) connected to a battery (15) and a ground line (Lg) and supplies the converted power to a load (80), comprising: multiple power converters; multiple reverse connection protection relays (521, 522) provided in the power supply line between the battery and the power converter of each system, with diodes connected in parallel to conduct current from the battery side to the power converter side, and that cut off current from the power converter side to the battery side when turned off; a common input capacitor (553) whose high-potential side electrode is connected to the power supply line connected to each other between the multiple systems on the power converter side of the reverse connection protection relay of each system, and whose low-potential side electrode is connected to the ground line; and a boost circuit (20) that boosts the input voltage supplied from the battery to a target voltage. a precharge circuit (30) that applies the boosted voltage output by the boost circuit to a high-potential side electrode of the common input capacitor for precharging; and a monitoring circuit (40) that detects a stuck-off abnormality of the reverse connection protection relay of each system during an initial check of the power supply device, wherein the power supply line between the battery and the reverse connection protection relay of each system is not provided with a power relay that cuts off a current from the battery side to the power converter side when the power relay is turned off, and during the initial check, the boost circuit performs an overboost process that temporarily increases the target voltage above a value during normal operation, and the precharge circuit applies the boosted voltage (VS) obtained by the overboost process to the high-potential side electrode of the common input capacitor, and the monitoring circuit detects a stuck-off abnormality for the reverse connection protection relay of each system one by one in sequence according to a post-relay voltage (Vry) that is a voltage on the power converter side of the reverse connection protection relay.

2. The power supply device of claim 1, wherein one of the reverse connection protection relays that is the target of detection for a stuck-off abnormality by the monitoring circuit is a detection target relay, and one or more of the reverse connection protection relays other than the detection target relay are non-detection target relays, the monitoring circuit performs the overvoltage boost process with all of the reverse connection protection relays turned OFF, and then turns on the detection target relay with the non-detection target relays turned OFF, and detects a stuck-off abnormality of the detection target relay based on the post-relay voltage after a predetermined voltage drop time (TD) has elapsed since the application of the boosted voltage by the overvoltage boost process ended (te1, te2).

3. The power supply device of claim 1, wherein one of the reverse connection protection relays that is the target of detection for a stuck-off abnormality by the monitoring circuit is a detection target relay, and one or more of the reverse connection protection relays other than the detection target relay are non-detection target relays, and the potential difference obtained by subtracting the battery voltage (Vb) from the relay post-voltage is defined as a potential difference across the relay (ΔV), then the monitoring circuit performs the overvoltage boost process with all of the reverse connection protection relays turned OFF, and then turns on the detection target relay with the non-detection target relays turned OFF, and detects a stuck-off abnormality of the detection target relay based on the potential difference across the relay after a predetermined potential difference reduction time (Tdd) has elapsed since the application of the boosted voltage by the overvoltage boost process ended (te1, te2).

4. A power supply device as claimed in claim 2 or 3, wherein the period from when the boost circuit finishes the overvoltage processing for one of the relays to be detected until when it starts the overvoltage processing for the next relay to be detected is defined as an overvoltage interval, and the precharge circuit continues to maintain the ON state of precharging the common input capacitor during at least one of the overvoltage intervals.

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