Power supply device

Abstract

To provide an electric power supply device which has constitution not comprising an electric power source relay, and in which dark current is prevented from flowing.SOLUTION: An inverter (an electric power converter) 60 includes switching elements 61 to 66 of one or more pairs of upper lower arms serially connected between an electric power source line Lp and a ground line Lg, and converts a direct current electric power of a battery 15 and supplies the electric power to a motor (a load) 80. Pull-up resistors Ruu, Ruv, and Ruw are connected between arm interval connection points Nu, Nv, and Nw, respectively, the arm interval connection points Nu, Nv, and Nw being connection points of the electric power source line Lp and the switching elements of upper lower arms. Each of pull-down resistors Rdu, Rdv, and Rdw is connected between the arm interval connection points Nu, Nv, and Nw. A dark current cutting switch 56 is provided between a reverse connection protection relay 52 and each of the pull-up resistors Ruu, Ruv, and Ruw, and when driving of the electric power supply device 10 is stopped, the dark current cutting switch 56 is turned OFF, and intercepts a dark current flowing in a ground via each pull-up resistor and each pull-down resistor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power supply device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been known a power supply device that converts DC power from a battery using a power converter such as an inverter and supplies the converted power to a load such as a three-phase motor.

[0003] For example, the device disclosed in Patent Document 1 has pull-up and pull-down resistors connected to the upper and lower arm connection points of each phase of the inverter, and detects a fault in the motor relay based on the voltage at the voltage division point during an initial check. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-174419 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the device of Patent Document 1, a power supply relay and a reverse connection protection relay are provided in the power supply line between the battery and the inverter. When the system is stopped, the power supply relay and the reverse connection protection relay are turned off to prevent the battery voltage from being applied to the inverter.

[0006] Incidentally, there is a demand to eliminate the power relay in order to reduce the number of parts. By not providing a power relay, the battery voltage is applied to the capacitor of the inverter input section even when the system is stopped, and there is an advantage in that the charging voltage is stabilized. However, the device configuration of Patent Document 1 has a problem in that, when the system is stopped, a dark current flows from the battery through the parasitic diode of the reverse connection protection relay, and further through the pull-up resistor and pull-down resistor to ground.

[0007] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a power supply device that prevents a dark current from flowing in a configuration that does not include a power relay. [Means for solving the problem]

[0008] The power supply device of the present invention includes a power converter (60), one or more pull-up resistors (Ruu, Ruv, Ruw), one or more pull-down resistors (Rdu, Rdv, Rdw), a reverse connection protection relay (52), and a control unit (40).

[0009] The power converter includes one or more pairs of upper and lower arm switching elements (61-66) connected in series between a power supply line (Lp) connected to the battery (15) and a ground line (Lg), and converts the DC power of the battery and supplies it to a load (80).

[0010] The pull-up resistors are connected between the power supply lines and the inter-arm connection points (Nu, Nv, Nw) which are the connection points of the switching elements of the upper and lower arms, and the pull-down resistors are connected between the inter-arm connection points and ground.

[0011] The reverse connection protection relay is provided in the middle of the power line, and has a return diode connected in parallel to it that conducts current from the battery side to the power converter side, and cuts off the current from the power converter side to the battery side when it is turned off. The control unit controls the operation of the power converter and the reverse connection protection relay.

[0012] Furthermore, this power supply device does not include a power supply relay in the power supply line between the battery and the reverse connection protection relay, which cuts off the current from the battery side to the power converter side when the relay is turned off.

[0013] This power supply device further includes a dark current cut switch (56, 58). The dark current cut switch is provided between the reverse connection protection relay and the pull-up resistor, and turns off when the power supply device stops operating, cutting off the dark current that flows to ground via the pull-up resistor and the pull-down resistor. For example, the dark current cut switch is configured with an N-channel FET or a P-channel FET. This makes it possible to prevent dark current from flowing while the system is stopped in a configuration that does not include a power supply relay. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a circuit diagram of a power supply device according to a first embodiment. [Diagram 2] FIG. 7 is a circuit diagram of a power supply device according to a second embodiment. [Diagram 3] 11 is a diagram showing a voltage after the dark current cut switch when the dark current cut switch is abnormally stuck on and when the dark current cut switch is abnormally stuck off. [Figure 4] 1A and 1B are diagrams illustrating detection of an abnormality in a dark current cut switch that is stuck on when the dark current cut switch is turned off and an abnormality in a dark current cut switch that is stuck off when the dark current cut switch is turned on. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Power supply devices according to multiple embodiments of the present invention will be described with reference to the drawings. Components that are substantially the same in multiple embodiments will be given the same reference numerals and descriptions thereof will be omitted. The first and second embodiments will be collectively referred to as "the present embodiment." The power supply device of the present 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.

[0016] Specifically, similar to the abnormality detection device of Patent Document 1 (JP Patent Publication 2020-174419 A), the ECU of the electric power steering device functions as a power supply device. The ECU is composed of a microcomputer, a pre-driver, etc., and includes a CPU, ROM, I / O, and a bus line connecting these components (not shown). The ECU executes software processing by executing a pre-stored program in the CPU, and executes control by hardware processing using a dedicated electronic circuit.

[0017] The ECU of an electric power steering device generally starts up (i.e. starts driving) when the vehicle ignition signal is turned ON, and stops driving when the ignition signal is turned OFF. Hereinafter, the state in which the ECU is operating is also referred to as "system in operation", and the state in which the ECU stops driving is also referred to as "system stopped". In this embodiment, the configuration for performing normal control of the motor while the system is operating is the same as that of a general motor control device. In this embodiment, attention is particularly focused on preventing dark current from flowing in the circuit while the system is stopped.

[0018] The first and second embodiments share the same basic circuit configuration and the idea of ​​blocking dark current, but differ in some specific configurations for blocking dark current. Below, the matters common to each embodiment will be described as the configuration of "this embodiment", and then the differences between the first and second embodiments will be described. Although Figures 1 and 2 show a single-system circuit configuration, as disclosed in Figure 2 of Patent Document 1, the present invention may be applied to a two-system configuration.

[0019] (First embodiment) The configuration of the first embodiment is shown in Fig. 1. A power supply device 10 supplies three-phase AC power generated by an inverter 60 serving as a "power converter" to three-phase windings 81, 82, and 83 of a motor 80. For example, in the case of a Y-connected motor 80, the three-phase windings 81, 82, and 83 are connected at a neutral point 84. The three-phase windings 81, 82, and 83 may also be delta-connected.

[0020] The power supply device 10 includes an inverter 60, a smoothing capacitor 55, a reverse connection protection relay 52, motor relays 71, 72, 73, pull-up resistors Ruu, Ruv, Ruw, and pull-down resistors Rdu, Rdv, Rdw, etc. The power supply device 10 also includes a control unit 40. As indicated by the arrows, the control unit 40 outputs ON / OFF signals to the switching elements 61-66 of the inverter 60, the reverse connection protection relay 52, the motor relays 71, 72, 73, etc., to control their operation.

[0021] The inverter 60 is connected to the positive electrode of the battery 15 via a power supply line Lp, and is connected to the negative electrode of the battery 15 via a ground line Lg. The inverter 60 includes three sets of upper and lower arm switching elements 61-66 connected in series between the power supply line Lp and the ground line Lg. More specifically, the upper arm switching elements 61, 62, 63 and the lower arm switching elements 64, 65, 66 of the U-phase, V-phase, and W-phase are bridge-connected. The inverter 60 converts the DC power of the battery 15 and supplies it to three-phase windings 81, 82, 83 of the motor 80.

[0022] In this embodiment, MOSFETs are used as the switching elements 61-66 of the inverter 60. Hereinafter, the switches other than the MOSFET used as the dark current cut switch in the second embodiment are basically N-channel MOSFETs. In the switching elements 61-66, a free wheel diode that conducts a current from the low potential side to the high potential side is configured as a parasitic diode inside the element. The connection points of the switching elements of the upper and lower arms of each phase are defined as "inter-arm connection points Nu, Nv, Nw". A smoothing capacitor 55 provided at the input part of the inverter 60 smoothes the input voltage to the inverter 60.

[0023] A reverse connection protection relay 52 is provided in the power supply line Lp from the battery 15 to the inverter 60. A free wheel diode that conducts a current from the battery 15 side to the inverter 60 side is connected in parallel to the reverse connection protection relay 52. ​​In this embodiment, a parasitic diode of a MOSFET that constitutes the reverse connection protection relay 52 conducts a current from the battery 15 side to the inverter 60 side. When the reverse connection protection relay 52 is turned off, it cuts off the current from the inverter 60 side to the battery side.

[0024] 2 of Patent Document 1, a power supply relay labeled with the reference symbol "51" is provided in the power supply line between the battery and the reverse connection protection relay. This power supply relay is connected so that the orientation of its parasitic diode is opposite to that of the reverse connection protection relay, and when it is turned off, it cuts off the current from the battery side to the inverter side.

[0025] In contrast, the power supply device 10 of this embodiment does not have a power relay at the position X indicated by the two-dot chain line. This allows the number of power relay components to be reduced in this embodiment. Also, even when the power supply device 10 is stopped and the system is stopped, the battery voltage is applied to the smoothing capacitor 55, and the charging voltage is stabilized. On the other hand, the disadvantage of not having a power relay will be described later.

[0026] The motor relays 71, 72, 73 are provided in motor current paths between inter-arm connection points Nu, Nv, Nw of each phase and three-phase windings 81, 82, 83, and cut off the motor current paths when turned off. For example, the motor relays 71, 72, 73 are composed of MOSFETs, and the parasitic diodes conduct current from the inter-arm connection points Nu, Nv, Nw to the three-phase windings 81, 82, 83.

[0027] The pull-up resistors Ruu, Ruv, and Ruw are connected between the power supply line Lp and the arm connection points Nu, Nv, and Nw of each phase. The pull-down resistors Rdu, Rdv, and Rdw are connected between the arm connection points Nu, Nv, and Nw of each phase and the ground. For example, as in the abnormality detection device of Patent Document 1, each pull-down resistor Rdu, Rdv, and Rdw may be two voltage dividing resistors connected in series. Furthermore, an abnormality in the motor relays 71, 72, and 73 or the three-phase windings 81, 82, and 83 may be detected based on the voltage at a voltage dividing point, which is the connection point of the two voltage dividing resistors.

[0028] In short, the power supply line Lp is connected to the ground via the pull-up resistors Ruu, Ruv, Ruw and the pull-down resistors Rdu, Rdv, Rdw. The point of this embodiment is that it has such a circuit configuration, and the functions of the pull-up resistors Ruu, Ruv, Ruw and the pull-down resistors Rdu, Rdv, Rdw are not limited. For example, it does not matter what is detected based on the voltage division of the pull-down resistors Rdu, Rdv, Rdw.

[0029] Here, attention is focused on the behavior of the system during system shutdown in this embodiment that does not include a power supply relay. When the power supply device 10 stops driving, the switching elements of the inverter 60, the reverse connection protection relay 52, and the motor relays 71, 72, and 73 are all turned off, but the current path via the parasitic diodes remains. Therefore, a dark current flows from the battery 15 to the ground via the parasitic diodes of the reverse connection protection relay 52, and further via the pull-up resistors Ruu, Ruv, and Ruw and the pull-down resistors Rdu, Rdv, and Rdw of each phase.

[0030] Even if the current value of the dark current is small, if it continues to flow for a long time, it may consume unnecessary battery power and lead to depletion. Therefore, the power supply device 10 of this embodiment is provided with a dark current cut switch between the reverse connection protection relay 52 and the pull-up resistors Ruu, Ruv, and Ruw. The dark current cut switch turns OFF when the power supply device 10 stops operating, and cuts off the dark current flowing to ground via the pull-up resistors Ruu, Ruv, and Ruw and the pull-down resistors Rdu, Rdv, and Rdw. The control unit 40 has a driver 45 that directly or indirectly turns ON / OFF the dark current cut switch.

[0031] Next, the configuration of the dark current cut switch 56 of the first embodiment will be described in detail. In the first embodiment, the dark current cut switch 56 is configured with an N-channel ("Nch" in the figure) MOSFET. The drain of the dark current cut switch 56 is connected to the inverter 60 side of the reverse connection protection relay 52, and the source of the dark current cut switch 56 is connected to the high potential side of the pull-up resistors Ruu, Ruv, and Ruw.

[0032] The gate of the dark current cut switch 56 is connected to the driver 45 of the control unit 40. A Zener diode ZD is connected in parallel between the source and gate of the dark current cut switch 56. The dark current cut switch 56 and the Zener diode ZD may be provided inside an ASIC (i.e., a customized IC). This reduces the board mounting area and the number of mounting steps.

[0033] During system operation, the driver 45 constantly outputs a Hi-level gate signal to the dark current cut switch 56, turning on the drain-source of the dark current cut switch 56. Therefore, a current flows from the power supply line Lp to the pull-up resistors Ruu, Ruv, and Ruw.

[0034] When the system stops and the power supply device 10 stops driving, the gate signal from the driver 45 becomes low level and the dark current cut switch 56 turns off. Therefore, the current flowing to ground via the pull-up resistors Ruu, Ruv, Ruw and the pull-down resistors Rdu, Rdv, Rdw is cut off. Therefore, in a configuration that does not include a power relay, it is possible to prevent dark current from flowing while the system is stopped.

[0035] In the first embodiment, the dark current cut switch 56 is configured with an N-channel MOSFET, so the number of elements can be reduced compared to when it is configured with a P-channel MOSFET. When the battery voltage is relatively low (for example, 12 V), the required gate voltage is relatively low, so there is no problem in terms of the boosting ability of the boost circuit.

[0036] Second embodiment A second embodiment will be described with reference to Fig. 2. The configuration other than the dark current cut switch is the same as that in Fig. 1. In the second embodiment, the dark current cut switch 58 is configured with a P-channel ("Pch" in the figure) MOSFET. The source of the dark current cut switch 58 is connected to the inverter 60 side of the reverse connection protection relay 52, and the drain of the dark current cut switch 58 is connected to the high potential side of the pull-up resistors Ruu, Ruv, and Ruw.

[0037] The gate of the dark current cut switch 58 is grounded via a resistor RS2 and a driver switch 57 configured with an N-channel MOSFET. The gate of the driver switch 57 is connected to a driver 45 of the control unit 40. A Zener diode ZD and a resistor RS1 are connected in parallel between the source and gate of the dark current cut switch 58. The dark current cut switch 58, the driver switch 57, and each of the peripheral elements may be provided inside the ASIC. This reduces the board mounting area and the number of mounting steps.

[0038] During system operation, the driver 45 constantly outputs a Hi-level gate signal to the driver switch 57. When the driver switch 57 is turned ON, a current flows from the power supply line Lp through the resistors Rs1 and Rs2 and the driver switch 57, and the gate voltage of the dark current cut switch 58 drops. As a result, the gate of the dark current cut switch 58 becomes Lo level, and the source-drain is turned ON. Therefore, a current flows from the power supply line Lp to the pull-up resistors Ruu, Ruv, and Ruw.

[0039] When the system stops and the power supply device 10 stops driving, the gate signal from the driver 45 becomes Lo level and the driver switch 57 turns OFF. As a result, the gate of the dark current cut switch 58 becomes Hi level and the source-drain is turned OFF. Therefore, the current flowing to ground via the pull-up resistors Ruu, Ruv, Ruw and the pull-down resistors Rdu, Rdv, Rdw is cut off. Therefore, in a configuration that does not include a power relay, it is possible to prevent dark current from flowing while the system is stopped.

[0040] In the second embodiment, two switches are required: a dark current cut switch 58 and a driver switch 57. However, when the battery voltage is relatively high (for example, 48 V), configuring the dark current cut switch with an N-channel MOSFET requires a high gate voltage, and the boost circuit is required to have an excessively large boosting capability. In contrast, by configuring the dark current cut switch with a P-channel MOSFET, the boost voltage by the boost circuit can be reduced.

[0041] (Initial check of dark current cut switch) 3 and 4, an initial check that is performed when the power supply device 10 is started up and detects whether the dark current cut switch is stuck in the ON state or the OFF state will be described. This initial check is commonly applicable to the N-channel MOSFET and P-channel MOSFET dark current cut switches 56, 58 according to the first and second embodiments. In the description of this portion, the reference numerals "56, 58" of the dark current cut switches will be omitted.

[0042] As shown in FIG. 1 and FIG. 2, the control unit 40 has a monitoring circuit 46 that detects an abnormality in the dark current cut switch. The monitoring circuit 46 acquires a voltage Vcs after the dark current cut switch, which is the voltage on the pull-up resistors Ruu, Ruv, and Ruw side of the dark current cut switch. In addition, the voltage of the power line Lp between the reverse connection protection relay 52 and the dark current cut switch is defined as a "voltage Vry after the reverse connection protection relay." During system shutdown, the reverse connection protection relay 52 is OFF, and the voltage obtained by subtracting the voltage drop Vf of the parasitic diode of the reverse connection protection relay 52 from the battery voltage Vb becomes the voltage Vry after the reverse connection protection relay (Vry=Vb-Vf).

[0043] As shown in Figure 3, when the dark current cut switch is normal, the voltage Vcs after the dark current cut switch is 0 [V] when the dark current cut switch is OFF, and is equal to the voltage Vry after the reverse connection protection relay when it is ON. When the dark current cut switch is stuck-ON abnormally, the voltage Vcs after the dark current cut switch when turned OFF will be close to the voltage Vry after the reverse connection protection relay. When the dark current cut switch is stuck-OFF abnormally, the voltage Vcs after the dark current cut switch when turned ON will be close to 0 [V].

[0044] Figures 4(a) and (b) show the anomaly detection logic that takes into account the fluctuation of the battery voltage Vb. The threshold value Vth is set as shown in the following formula, assuming that the battery voltage Vb is equal to or greater than the minimum value Vb_min. The margin is determined taking into account the detection error and variation. Vth=Vb_min-Vf-Margin

[0045] 4(a), if the dark current cut switch is normal during the OFF operation, the voltage Vcs after the dark current cut switch is 0 [V] regardless of the battery voltage Vb and is below the threshold value Vth. If the dark current cut switch is stuck ON abnormally, the voltage Vcs after the dark current cut switch has a positive correlation with the battery voltage Vb and is greater than the threshold value Vth.

[0046] As shown in Fig. 4(b), if the dark current cut switch is normal when turned ON, the voltage Vcs after the dark current cut switch has a positive correlation with the battery voltage Vb and is equal to or greater than the threshold value Vth. If the dark current cut switch is stuck OFF, the voltage Vcs after the dark current cut switch is 0 [V] regardless of the battery voltage Vb, and is smaller than the threshold value Vth.

[0047] In this way, the monitoring circuit 46 compares the post-dark current cut switch voltage Vcs when the dark current cut switch is turned OFF and ON with the threshold value Vth, and detects ON-fixed abnormality and OFF-fixed abnormality of the dark current cut switch. Here, the threshold value Vth when the dark current cut switch is turned OFF and ON is not limited to being the same value, and may be set to different values. If an abnormality of the dark current cut switch is detected in the initial check, the control unit 40 takes abnormality action, such as issuing an alarm. The abnormality action may be switched depending on the abnormality mode.

[0048] (Other embodiments) (a) 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. The number of switching elements in the upper and lower arms of the inverter is not limited to three sets, but may be one set or more. As the "power converter", an H-bridge circuit or the like may be used instead of a multi-phase inverter.

[0049] (b) A FET (field effect transistor) other than a MOSFET may be used as the semiconductor switching element constituting the dark current cut switch. If the MOSFET is expanded to a general FET, the dark current cut switch 56 of the first embodiment is composed of an N-channel FET, and the dark current cut switch 58 of the second embodiment is composed of a P-channel FET. Furthermore, the dark current cut switch is not limited to a FET, and may be composed of other types of semiconductor switching elements, mechanical relays, etc.

[0050] (c) As described in the above embodiment, the dark current cut switch and at least some of its peripheral elements such as the Zener diode and resistor may be provided inside the ASIC.

[0051] The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the present invention.

[0052] The control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer. [Explanation of symbols]

[0053] 10...power supply device, 15 battery, 40 control unit, 52 Reverse polarity protection relay, 56, 58: Dark current cut switch, 60... Inverter (power converter), 61-66... ​​Switching element, 80 Motor (load), Lp...Power line, Lg...Ground line, Nu, Nv, Nw: Inter-arm connection points, Ruu, Ruv, Ruw... pull-up resistors, Rdu, Rdv, Rdw... Pull-down resistors.

Claims

1. a power converter (60) including one or more pairs of upper and lower arm switching elements (61-66) connected in series between a power supply line (Lp) connected to a battery (15) and a ground line (Lg), for converting DC power of the battery and supplying the converted power to a load (80); one or more pull-up resistors (Ruu, Ruv, Ruw) connected between the power supply line and an inter-arm connection point (Nu, Nv, Nw) which is a connection point of the switching elements of the upper and lower arms; One or more pull-down resistors (Rdu, Rdv, Rdw) connected between the inter-arm connection point and ground; a reverse connection protection relay (52) that is provided in the middle of the power supply line, has a return diode that conducts a current from the battery side to the power converter side connected in parallel, and cuts off the current from the power converter side to the battery side when the relay is turned off; A control unit (40) for controlling operations of the power converter and the reverse connection protection relay; Equipped with A power supply device in which a power supply relay that cuts off a current from the battery side to the power converter side when the power supply relay is turned off is not provided in the power supply line between the battery and the reverse connection protection relay, The power supply device further includes a dark current cut switch (56, 58) that is provided between the reverse connection protection relay and the pull-up resistor, and that is turned OFF when the power supply device is stopped, thereby cutting off dark current that flows to ground via the pull-up resistor and the pull-down resistor.

2. 2. The power supply device according to claim 1, wherein the dark current cut switch (56) is composed of an N-channel FET.

3. 2. The power supply device according to claim 1, wherein the dark current cut switch (58) is composed of a P-channel FET.

4. During the initial check of the power supply device, The power supply device according to any one of claims 1 to 3, wherein the control unit detects an ON-fixed abnormality or an OFF-fixed abnormality of the dark current cut switch based on the voltage (Vcs) on the pull-up resistor side of the dark current cut switch.

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