Abnormality detection device

Abstract

The pull-down resistors (Rdu, Rdv, Rdw) are configured from two divider resistors that divide a voltage between an inter-arm connection point (Nu, Nv, Nw), which is a connection point between the upper arm elements (61, 62, 63) and the lower arm elements (64, 65, 66), and the ground, and the inter-arm connection point is connected to the ground. A determination unit (25) detects an abnormality in at least the upper arm element and the lower arm element on the basis of a voltage at a voltage division point, which is a connection point between the two voltage division resistors. The power supply line (Lp) and the inter-arm connection point are not connected via the pull-up resistor. The determination unit (25) detects an on-adhesion abnormality and an off-adhesion abnormality between the upper arm element and the lower arm element on the basis of a voltage at a voltage dividing point when a leakage current (IL) flows from the upper arm element drive circuit to ground via the pull-down resistor during operation of the upper arm element drive circuits (31, 32, 33).

Description

[0001] Cross-references of related applications

[0002] This application is based on Japanese application No. 2022-170553 filed on October 25, 2022, and the contents thereof are cited herein. Technical Field

[0003] The present disclosure relates to an abnormality detection device. Background Art

[0004] In the past, there is a known device for detecting abnormalities of relays and the like composed of semiconductor switching elements during the initial verification of a circuit for supplying power to a multi-phase motor. For example, in the abnormality detection device disclosed in Patent Document 1, a pull-up resistor and a pull-down resistor are connected to the upper and lower arm connection points of each phase of the inverter. The pull-down resistor of each phase is composed of two voltage-dividing resistors connected in series. The determination unit determines the connection adhesion abnormality (short-circuit fault) and disconnection adhesion abnormality (open-circuit fault) of the motor relay based on the voltage of the voltage-dividing point as the connection point of the two voltage-dividing resistors.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2020-174419

[0008] In the prior art of Patent Document 1, at least the pull-down resistor of the pull-up resistor and the pull-down resistor for voltage monitoring is arranged inside the driving circuit IC to suppress the increase in the substrate mounting area. However, the idea of ​​using the voltage obtained by stepping down the voltage of the power line through the pull-up resistor to perform abnormality detection is basic, so regardless of whether the pull-up resistor is arranged inside the driving circuit IC or mounted on the substrate, the pull-up resistor is necessary as a component. In particular, in the structure where the pull-up resistor is mounted on the substrate, although there is room for further reducing the substrate mounting area, Patent Document 1 does not mention the possibility of removing the pull-up resistor at all. Summary of the invention

[0009] An object of the present disclosure is to provide an abnormality detection device capable of eliminating a pull-up resistor for voltage monitoring.

[0010] The abnormality detection device of the present disclosure includes an inverter, an upper arm element drive circuit, a lower arm element drive circuit, a plurality of pull-down resistors, and a determination unit.

[0011] The inverter is composed of upper arm elements and lower arm elements of multiple phases connected by bridge connection between the power line connected to the battery and the ground line, converting the DC power of the battery and supplying it to each phase winding of the multi-phase motor. The upper arm element drive circuit outputs a gate signal to the upper arm element. The lower arm element drive circuit outputs a gate signal to the lower arm element.

[0012] The plurality of pull-down resistors are composed of two voltage-dividing resistors for each phase that divide the voltage between an inter-arm connection point and ground, and the inter-arm connection point is connected to ground. The inter-arm connection point is a connection point between an upper arm element and a lower arm element of each phase. The determination unit detects an abnormality of at least the upper arm element and the lower arm element based on a voltage at a voltage-dividing point that is a connection point between the two voltage-dividing resistors.

[0013] The power supply line is connected to the inter-arm connection point of each phase without a pull-up resistor.

[0014] The determination unit detects ON-sticking abnormality and OFF-sticking abnormality of the upper and lower arm elements based on the voltage at the voltage dividing point when a leakage current flows from the upper arm element drive circuit to the ground via the pull-down resistor during operation of the upper arm element drive circuit.

[0015] In the present disclosure, the voltage obtained by stepping down the power line voltage by the pull-up resistor is not used, but the voltage generated by the leakage current from the upper arm element driving circuit flowing through the pull-down resistor is used to detect abnormality. By removing the pull-up resistor for voltage monitoring, the number of components can be reduced, and the substrate mounting area of ​​the pull-up resistor can be further reduced.

[0016] In addition, in Patent Document 1, "the floating voltage increases due to the leakage current from the (upper arm element) drive circuit to the pull-down resistor, which becomes an error factor." Thus, the leakage current is considered to be a disadvantage. And when the abnormality of the motor relay is detected, the operation of the drive circuit is stopped to cut off the leakage current as a solution to reduce the error. In contrast, in the present disclosure, the pull-up resistor can be eliminated by actively using the leakage current as a voltage source for voltage monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above-mentioned object and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings.

[0018] Figure 1 This is a circuit diagram of an abnormality detection device according to one embodiment.

[0019] Figure 2 It means about Figure 1 Diagram of the structure of voltage monitoring of one phase, phase U.

[0020] Figure 3A This is a judgment diagram for the upper arm element connection adhesion abnormality without cutting off the leakage.

[0021] Figure 3B This is a diagram for determining an upper arm element ON-sticking abnormality in a state where the operation of the upper arm element driving circuit is stopped (there is an off-leakage).

[0022] Figure 4 This is a judgment diagram for upper arm component disconnection adhesion abnormality.

[0023] Figure 5 This is a judgment diagram for abnormal connection of lower arm components.

[0024] Figure 6 This is a judgment diagram for the abnormal disconnection of the lower arm component.

[0025] Figure 7 This is a diagram of the current path when the U-phase motor relay is turned on and the adhesion abnormality is checked normally.

[0026] Figure 8 This is a diagram of the current path during abnormality inspection of the U-phase motor relay when it is turned on and sticking.

[0027] Fig. 9 This is a judgment diagram for abnormal sticking of the U-phase motor relay.

[0028] Fig.10 This is a diagram of the current path during normal operation during the U-phase motor relay disconnection adhesion abnormality check.

[0029] Fig.11 This is a diagram of the current path during the abnormality check of the U-phase motor relay disconnection adhesion abnormality.

[0030] Fig.12 This is the judgment diagram for the U-phase motor relay disconnection adhesion abnormality. DETAILED DESCRIPTION

[0031] (One embodiment)

[0032] Based on the accompanying drawings, an abnormality detection device of an embodiment is described. The abnormality detection device of this embodiment is applied to a circuit that supplies power to a multi-phase motor used as a steering assist motor of an electric power steering device, for example. The abnormality detection device detects the connection adhesion abnormality (short circuit fault) and disconnection adhesion abnormality (open circuit fault) of the upper and lower arm elements of the inverter and the motor relay during the initial verification of the power supply circuit.

[0033] Specifically, similar to Patent Document 1 (Japanese Patent Publication No. 2020-174419, corresponding US Publication: US2020 / 0321902A1), the ECU of the electric power steering device functions as an abnormality detection device. The ECU is composed of a microcomputer, a pre-driver, etc., and has a CPU, ROM, RAM, I / O, and a bus connecting these structures, etc. (not shown). The ECU performs control based on software processing by the CPU executing a pre-stored program and hardware processing based on a dedicated electronic circuit.

[0034] Figure 1 The structure of one embodiment is shown. In this embodiment, a three-phase motor 80 is used as a "multi-phase motor". Hereinafter, the three-phase motor 80 is simply referred to as the motor 80. The ECU 10 as an abnormality detection device supplies the three-phase AC power generated by the inverter 60 to the three-phase windings 81, 82, 83 of the motor 80. For example, in the case of a Y-connected motor 80, the three-phase windings 81, 82, 83 are connected at a neutral point 84. In addition, the three-phase windings 81, 82, 83 may also be Δ-connected.

[0035] After the vehicle switch is turned on, the ECU 10 detects an abnormality in the power supply circuit to the motor as an initial check before the motor drive starts. In the initial check, if the power supply circuit to the motor 80 is determined to be normal, the ECU 10 controls the drive of the motor 80 based on the steering torque so that the motor 80 generates the desired assist torque.

[0036] The ECU 10 includes a filter capacitor 55, an inverter 60, motor relays 71, 72, 73, a drive circuit IC 30, and a microcomputer 20. The internal structure of the drive circuit IC 30 will be described later. The microcomputer 20 includes a determination unit 25 for detecting an abnormality of a target element.

[0037] The inverter 60 is connected to the positive electrode of the battery 15 via the power line Lp, and is connected to the negative electrode of the battery 15 via the ground line Lg. The inverter 60 is configured such that upper arm elements 61, 62, 63 and lower arm elements 64, 65, 66 of three phases, namely, U phase, V phase, and W phase, are bridge-connected between the power line Lp and the ground line Lg. Hereinafter, the upper arm elements 61, 62, 63 and the lower arm elements 64, 65, 66 may be collectively referred to as "upper and lower arm elements 61 to 66". The inverter 60 converts the DC power of the battery 15 and supplies it to the three-phase windings 81, 82, 83 of the motor 80.

[0038] The filter capacitor 55 provided at the input portion of the inverter 60 smoothes the input voltage to the inverter 60. A power supply relay or a reverse connection protection relay may be provided in the middle of the power supply line Lp from the battery 15 to the inverter 60.

[0039] In the inverter 60, the connection points of the upper arm elements 61, 62, 63 and the lower arm elements 64, 65, 66 of each phase are defined as "inter-arm connection points Nu, Nv, Nw". The motor relays 71, 72, 73 are provided in the motor current path connecting the inter-arm connection points Nu, Nv, Nw of each phase of the inverter 60 and the three-phase windings 81, 82, 83 of the motor 80. The motor relays 71, 72, 73 are connected in parallel with parasitic diodes that conduct the current from the inverter 60 side to the motor 80 side, and cut off the current from the motor 80 side to the inverter 60 side when disconnected.

[0040] The upper and lower arm elements 61 to 66 and the motor relays 71, 72, 73 of this embodiment are composed of MOSFETs. In the motor relays 71, 72, 73, the parasitic diodes of the MOSFETs conduct the current from the inverter 60 side to the motor 80 side. In the upper and lower arm elements 61 to 66, the parasitic diodes of the MOSFETs conduct the current from the low potential side to the high potential side.

[0041] Here, Patent Document 1 Figure 2 Pull-up resistors Ruu, Ruv, and Ruw are shown for connecting the power line Lp to the motor current path of each phase. In contrast, in the present embodiment, the power line Lp is not connected to the arm connection points Nu, Nv, and Nw of each phase via a pull-up resistor. That is, in the ECU 10 of the present embodiment, the pull-up resistor is deleted compared to the prior art.

[0042] The driving circuit IC30 is a customized integrated IC. The driving circuit IC30 includes upper arm element driving circuits 31, 32, 33, lower arm element driving circuits 34, 35, 36, motor relay driving circuits 371, 372, 373, pull-down resistors Rdu, Rdv, Rdw of each phase, a multiplexer 38, and an amplifier circuit 39.

[0043] The upper arm element driving circuits 31, 32, 33 output gate signals to the upper arm elements 61, 62, 63. The lower arm element driving circuits 34, 35, 36 output gate signals to the lower arm elements 64, 65, 66. The motor relay driving circuits 371, 372, 373 output gate signals to the motor relays 71, 72, 73.

[0044] In the figure, the block of "upper arm element drive circuit 31, 32, 33" is correctly divided into three blocks: U-phase upper arm element drive circuit 31, V-phase upper arm element drive circuit 32, and W-phase upper arm element drive circuit 33, but considering the space, it is integrated into one block for illustration. The thin arrows from the blocks of upper arm element drive circuit 31, 32, 33 toward the double-dotted frame surrounding the upper arm elements 61, 62, 63 are integrated to represent the selection signals to the upper arm elements 61, 62, 63 of each phase.

[0045] The same is true for the lower arm element drive circuits 34, 35, 36 and the motor relay drive circuits 371, 372, 373. The block of "lower arm element drive circuits 34, 35, 36" collectively represents the U-phase lower arm element drive circuit 34, the V-phase lower arm element drive circuit 35, and the W-phase lower arm element drive circuit 36. The block of "motor relay drive circuits 371, 372, 373" collectively represents the U-phase motor relay drive circuit 371, the V-phase motor relay drive circuit 372, and the W-phase motor relay drive circuit 373.

[0046] In addition, the dotted line connecting the block of the "upper arm element driving circuit 31, 32, 33" and the inter-arm connection points Nu, Nv, Nw of each phase represents the path of the leakage current IL flowing when the upper arm element driving circuit 31, 32, 33 operates. The technical significance of the leakage current IL in this embodiment will be described later.

[0047] The pull-down resistors Rdu, Rdv, and Rdw are composed of two voltage-dividing resistors for each phase that divide the voltage between the inter-arm connection points Nu, Nv, and Nw of each phase and the ground, and the inter-arm connection points Nu, Nv, and Nw are connected to the ground. The voltage-dividing resistors on the side of the inter-arm connection points Nu, Nv, and Nw of the two voltage-dividing resistors of each phase are represented as first voltage-dividing resistors Rdu1, Rdv1, and Rdw1, and the voltage-dividing resistors on the ground side are represented as second voltage-dividing resistors Rdu2, Rdv2, and Rdw2. In addition, the connection point of the two voltage-dividing resistors is represented as voltage-dividing points Du, Dv, and Dw.

[0048] The voltages of the voltage dividing points Du, Dv, and Dw of each phase are input to a multiplexer ("MPX" in the figure) 38. The multiplexer 38 selects the voltage of the voltage dividing point Du, Dv, and Dw of a certain phase and outputs it to the amplifier circuit 39. The amplifier circuit 39 outputs the monitoring voltages Vua, Vva, and Vwa obtained by amplifying the voltages of the voltage dividing points Du, Dv, and Dw of the selected phase to the determination unit 25.

[0049] The determination unit 25 detects abnormalities of the upper and lower arm elements 61 to 66 and the motor relays 71, 72, 73 of the inverter 60 directly based on the monitoring voltages Vua, Vva, and Vwa. Fundamentally, the determination unit 25 detects abnormalities of the upper and lower arm elements 61 to 66 and the motor relays 71, 72, and 73 based on the voltages of the voltage dividing points Du, Dv, and Dw when the leakage current IL flows from the upper arm element drive circuits 31, 32, and 33 to the ground via the pull-down resistors Pdu, Pdv, and Pdw during the operation of the upper arm element drive circuits 31, 32, and 33. In addition, the dotted arrows from the microcomputer 20 to the drive circuit IC30 collectively represent various signals.

[0050] Next, refer to Figure 2 , the structure of voltage monitoring of one phase of U phase is explained. Figure 2 Basically equivalent to Patent Document 1 Figure 4 , there is no pull-up resistor Ruu connected in parallel with the U-phase upper arm element 61. As a slight difference, in this embodiment Figure 2 In the figure, the FETs in the drive circuits 31, 34, and 371 are omitted, and the circuit including the FETs is described as the drive circuit. In addition, the specific circuit diagram of the amplifier circuit 39 is omitted, and it is described only as a block.

[0051] The voltage dividing resistors are marked with "Rdu1, Rdu2" instead of "RduH, RduL" in Patent Document 1. The leakage current is marked with "IL" instead of "Lc" in Patent Document 1. Figure 2 In the patent document 1, the Figure 4 Symbols and marks.

[0052] Figure 2 The U phase is shown as a representative, and the symbols of the components of the U phase are used in the description. The same structure is also applied to the V phase and the W phase. In addition to the microcomputer 20 and the drive circuit IC 30 mounted as chips on the substrate 50, MOSFETs constituting the upper arm element 61, the lower arm element 64, and the motor relay 71 are also mounted.

[0053] The upper arm element drive circuit 31, the lower arm element drive circuit 34 and the motor relay drive circuit 371 are built in the drive circuit IC30. In addition, a pull-down resistor Rdu composed of two voltage-dividing resistors Rdu1 and Rdu2 connected in series, a multiplexer 38 and an amplifier circuit 39 are provided inside the drive circuit IC30. The multiplexer 38 is input with the voltage of the voltage-dividing point Du of the U phase. The terminals 41 to 49 of the drive circuit IC30 are the same as those in Patent Document 1, so the description thereof is omitted.

[0054] When the upper arm element driving circuit 31 is in operation, as shown by the thick arrow, the leakage current IL flows from the upper arm element driving circuit 31 to the ground via the pull-down resistor Rdu. In detail, when the upper arm element 61 is turned on, a leakage current IL larger than that when the upper arm element 61 is turned off flows. If the operation of the upper arm element driving circuit 31 stops, the leakage current IL does not flow. When the upper arm element driving circuit 31 is in operation, when both the upper arm element 61 and the lower arm element 64 are turned off, the motor terminal voltage V*mt (*=u, v, w) which is the voltage of the inter-arm connection points Nu, Nv, and Nw of each phase is expressed by formula (1). Here, R1 is the resistance value of the first voltage-dividing resistor Rd*1, and R2 is the resistance value of the second voltage-dividing resistor Rd*2.

[0055] V*mt=(R1+R2)×IL···(1)

[0056] The relationship between the monitoring voltage V*a input to the determination unit 25 and the motor terminal voltage V*mt (*=u, v, w) is expressed by equation (2) when the amplification factor of the amplifier circuit 39 is G. In a circuit without the amplifier circuit 39, G=1 is assumed. Thus, in the present embodiment, abnormality detection is performed using the voltage generated by the leakage current IL.

[0057] V*a=G×V*mt×R2 / (R1+R2)

[0058] =G×R2×IL···(2)

[0059] In the prior art of Patent Document 1, the basic idea is to detect abnormality by using a voltage obtained by stepping down the voltage of the power line Lp by a pull-up resistor. Therefore, regardless of whether the pull-up resistor is provided inside the drive circuit IC 30 as shown in FIG. 3 of Patent Document 1, or whether the pull-up resistor is provided inside the drive circuit IC 30 as shown in FIG. Figure 4 In particular, when the pull-up resistor is mounted on the substrate 50, the pull-up resistor is mounted on the substrate. Figure 4 In the structure of , although there is room for further reducing the substrate mounting area, Patent Document 1 does not mention the possibility of removing the pull-up resistor at all.

[0060] In addition, paragraphs

[0045] and

[0046] of Patent Document 1 state that "the floating voltage increases due to the leakage current from the upper arm element drive circuit to the pull-down resistor, and becomes a factor of error" and "when an abnormality is detected, the leakage current flowing in the pull-down resistor is cut off by stopping the operation of the upper arm element drive circuit, thereby minimizing the influence of the error." As described above, in Patent Document 1, the leakage current IL is considered to be a malpractice.

[0061] In contrast, in this embodiment, the pull-up resistor can be removed by actively using the leakage current IL as a voltage source for voltage monitoring. In this embodiment, by removing the pull-up resistor for voltage monitoring, the number of components can be reduced, and the substrate mounting area of ​​the pull-up resistor can be further reduced. In addition, by providing the upper arm element drive circuit 31 and the pull-down resistor Rdu in the same manner inside the drive circuit IC30, the terminal connection in the middle of the path of the leakage current IL disappears, thereby stabilizing the voltage.

[0062] Next, a specific method of detecting abnormality of the upper and lower arm elements 61 to 66 and the motor relays 71, 72, and 73 according to the present embodiment will be described in order. Figure 6 , the detection of the connection adhesion abnormality and disconnection adhesion abnormality of the upper arm elements 61, 62, 63 and the lower arm elements 64, 65, 66 is described. In the description, based on Figure 2 , using symbols such as the upper arm element 61 and the lower arm element 64 of the U phase as representatives.

[0063] In principle, the determination unit 25 detects the on-sticking abnormality and the off-sticking abnormality of the upper arm element 61 and the lower arm element 64 based on the voltage at the voltage dividing point Du when the leakage current flows from the upper arm element driving circuit 31 to the ground via the pull-down resistor Pdu during the operation of the upper arm element driving circuit 31. Here, "stopping the operation of the upper arm element driving circuit 31 and cutting off the leakage current IL" is referred to as "cutting off the leakage". In the present embodiment, in principle, the leakage current IL is not cut off. Figures 4 to 6 The abnormality determination diagram is shown in principle when the leakage is not cut off. However, only the on-state sticking abnormality check of the upper arm element 61 is divided into Figure 3A and Figure 3B The case of "no cut-off leakage" and the case of "with cut-off leakage".

[0064] The vertical axis of each graph is not the monitoring voltage V*a itself acquired by the determination unit 25, but a value converted into the motor terminal voltage V*mt (*=u, v, w). When both the upper arm element 61 and the lower arm element 64 are off, the value of equation (1) is "(R1+R2)×IL".

[0065] For detection of the ON sticking abnormality and OFF sticking abnormality of the upper arm element 61, refer to Figure 3A , Figure 3B , Figure 4 It is obvious that the upper arm element 61 is disconnected when the check for adhesion abnormality is turned on, and is connected when the check for adhesion abnormality is turned off. The lower arm element 64 is disconnected in either check.

[0066] like Figure 3AAs shown, in the connection sticking abnormality check of the upper arm element 61, when normally disconnected, the motor terminal voltage Vumt is "(R1+R2)×IL", which is lower than the threshold value Vth_H. On the other hand, the motor terminal voltage Vumt of the lower arm element 64 during the connection sticking abnormality rises as the battery voltage rises within a range higher than the threshold value Vth_H.

[0067] However, since the upper arm element 61 is disconnected during the on-sticking abnormality check of the upper arm element 61, the operation of the upper arm element drive circuit 31 may be stopped to set the leakage to a cut-off state. Therefore, the determination unit 25 can detect the on-sticking abnormality of the upper arm element 61 in a state where the operation of the upper arm element drive circuit 31 is stopped. Figure 3B As shown in FIG. 1 , in a state where there is a cutoff leakage, the motor terminal voltage Vumt during normal disconnection is a value close to the ground. This can ensure a greater margin for erroneous detection.

[0068] Since the upper arm element 61 needs to be turned on during the disconnection adhesion abnormality check of the upper arm element 61, the operation of the upper arm element driving circuit 31 cannot be stopped to cut off the leakage current IL. Figure 4 As shown, the motor terminal voltage Vumt when the upper arm element 61 is normally turned on increases with the increase of the battery voltage within a range higher than the threshold value Vth_H. On the other hand, the motor terminal voltage Vumt when the upper arm element 61 is disconnected and the adhesion is abnormal is "(R1+R2)×IL", which is lower than the threshold value Vth_H.

[0069] Next, regarding the detection of the ON sticking abnormality and the OFF sticking abnormality of the lower arm element 64, refer to Figure 5 , Figure 6 It is obvious that the lower arm element 64 is turned off when checking for adhesion abnormality when it is turned on, and is turned on when checking for adhesion abnormality when it is turned off. The upper arm element 61 is always turned off.

[0070] like Figure 5 As shown, in the on-stick abnormality check of the lower arm element 64, the motor terminal voltage Vumt during normal disconnection is "(R1+R2)×IL", which is higher than the threshold value Vth_L. On the other hand, the motor terminal voltage Vumt during the on-stick abnormality of the lower arm element 64 is a value near the ground, which is lower than the threshold value Vth_L. In addition, if the leakage is cut off, the voltage during normal disconnection is reduced, so abnormality detection becomes difficult. Therefore, in the on-stick abnormality check of the lower arm element 64, the leakage cannot be cut off.

[0071] like Figure 6As shown, in the disconnection adhesion abnormality check of the lower arm element 64, the motor terminal voltage Vumt when the lower arm element 64 is normally connected is a value near the ground, which is lower than the threshold value Vth_L. On the other hand, when the disconnection adhesion abnormality of the lower arm element 64 occurs, the motor terminal voltage Vumt is "(R1+R2)×IL", which is higher than the threshold value Vth_L.

[0072] As described above, regarding the detection of the on-sticking abnormality and the off-sticking abnormality of the upper and lower arm elements 61 to 66 of the inverter 60, by utilizing the leakage current flowing from the upper arm element drive circuit of each phase to the ground via the pull-down resistor, the pull-up resistor for voltage monitoring can be eliminated compared to the prior art. In addition, preferably, the determination unit 25 can ensure a greater margin for erroneous detection by detecting the on-sticking abnormality of the upper arm elements 61, 62, 63 in a state where the operation of the upper arm element drive circuits 31, 32, 33 is stopped.

[0073] Next, refer to Figure 7 to Figure 12 , the detection of the sticking anomaly during connection and the sticking anomaly during disconnection of the motor relays 71, 72, and 73 is described. The phase that is the object of the abnormality detection is called the object phase. In addition, one or two phases whose voltages at the voltage dividing points in the two phases other than the object phase are used for the abnormality detection based on the determination unit 25 are called monitoring phases. Here, the case where the U phase is the object phase and the V phase is the monitoring phase is described as an example. In the case where the U phase is the object phase, the W phase may be selected as the monitoring phase instead of the V phase or in addition. Figure 7 In the figure, the multiplexer 38 and the amplifier circuit 39 are omitted.

[0074] The determination unit 25 detects abnormality by using the voltage generated by the leakage current from the upper arm element drive circuit of the monitoring phase flowing through the pull-down resistor. In the abnormality detection of the motor relay, the operation of the upper arm element drive circuit of the monitoring phase is not stopped to cut off the leakage current IL. In this respect, the present embodiment is significantly different from the prior art of Patent Document 1.

[0075] For the U-phase motor relay 71 on-state adhesion abnormality check, refer to Figure 7 to Figure 9 . It is obvious that the motor relay 71 of the U phase, which is the target phase, is disconnected when checking the sticking abnormality. In addition, in the inverter 60, the upper arm elements 61, 62, 63 of all phases and the lower arm elements 65, 66 of the V phase and the W phase, which are two phases other than the target phase, are disconnected, and the lower arm element 64 of the U phase, which is the target phase, is connected. In addition, the motor relay 73 of the W phase, which is "a phase other than the target phase and other than the monitoring phase", is disconnected.

[0076] The motor relay 72 of the V phase as the monitoring phase can be either turned off or turned on. When the V phase motor relay 72 is turned off, the current flowing from the inverter 60 side to the motor 80 side passes through the parasitic diode of the MOSFET, so the voltage drop Vf of the parasitic diode occurs. When the V phase motor relay 72 is turned on, the current flows in the element body of the MOSFET, so the voltage drop is close to 0.

[0077] like Figure 7 As shown, when the U-phase motor relay 71 is normally disconnected, the path from the neutral point 84 of the motor 80 to the ground via the U-phase lower arm element 64 is cut off by the U-phase motor relay 71, and the leakage current IL from the V-phase upper arm element drive circuit 32 flows entirely through the pull-down resistor Rdv. Fig. 9 As shown, the motor terminal voltage Vvmt during normal disconnection is "(R1+R2)×IL", which is higher than the threshold value Vth_M.

[0078] like Figure 8 As shown, when the U-phase motor relay 71 is turned on and stuck abnormally, the path from the neutral point 84 of the motor 80 to the ground via the U-phase motor relay 71 and the U-phase lower arm element 64 is conductive. Therefore, as shown by the dotted line, only a small leakage current IL flows through the pull-down resistor Rdv.

[0079] like Fig. 9 As shown in FIG. 1 , in any case of the V-phase motor relay 72 being turned on / off, the motor terminal voltage Vvmt at the time of the on-state sticking abnormality is lower than the threshold value Vth_M. When the V-phase motor relay 72 is turned off, the motor terminal voltage Vvmt at the time of the on-state sticking abnormality is a value equivalent to the voltage drop Vf of the parasitic diode. On the other hand, when the V-phase motor relay 72 is turned on, the motor terminal voltage Vvmt at the time of the on-state sticking abnormality is a value close to the ground, which can ensure a greater margin for false detection.

[0080] Next, regarding the disconnection adhesion abnormality check of the U-phase motor relay 71, refer to Figure 10 to Figure 12 When checking the disconnection of the adhesion abnormality, it is obvious that the motor relay 71 of the U phase as the target phase is turned on. In addition, the upper and lower arm elements 61-66 of the inverter 60 and the motor relay 73 of the W phase as a phase other than the monitoring phase and the motor relay 72 of the V phase as the monitoring phase are turned on / off in the same manner as the check of the connection of the adhesion abnormality.

[0081] Fig.10 The current path during normal on-state operation is shown in Figure 8 The current path when the sticking abnormality is turned on is the same as shown. Fig.11 The current path when the adhesion is abnormal is shown in the figure. Figure 7 The current path for normal disconnection is the same as shown in Figure 1. Fig.12 As shown, the motor terminal voltage Vvmt when the adhesion abnormality is disconnected is "(R1+R2)×IL", which is higher than the threshold value Vth_M.

[0082] In addition, if Fig.12 As shown in FIG. 1 , in any case of the V-phase motor relay 72 being turned on / off, the motor terminal voltage Vvmt when normally turned on is lower than the threshold value Vth_M. When the V-phase motor relay 72 is turned off, the motor terminal voltage Vvmt when normally turned on is a value equivalent to the voltage drop Vf of the parasitic diode. On the other hand, when the V-phase motor relay 72 is turned on, the motor terminal voltage Vvmt when normally turned on is a value close to the ground, and a larger margin for false detection can be ensured.

[0083] As described above, regarding the detection of the on-sticking abnormality and the off-sticking abnormality of the motor relay of the target phase, it is also possible to eliminate the pull-up resistor for voltage monitoring compared to the prior art by utilizing the leakage current IL flowing from the upper arm element driving circuit of the monitoring phase to the ground via the pull-down resistor. In addition, it is preferable that the determination unit 25 detects the on-sticking abnormality and the off-sticking abnormality of the motor relay 71 of the U phase as the target phase based on the voltage of the voltage dividing point Dv of the monitoring phase when the leakage current IL flows when the motor relay 72 of the V phase as the monitoring phase is turned on. Thereby, it is possible to ensure a greater margin for erroneous detection.

[0084] (Other embodiments)

[0085] (a) The abnormality detection device of the present disclosure may also be applied to a power supply circuit that does not include a motor relay. In this case, the determination unit 25 may detect abnormalities of at least the upper arm elements 61 , 62 , 63 and the lower arm elements 64 , 65 , 66 .

[0086] (b) The pull-down resistors Pdu, Pdv, Pdw, multiplexer 38 and amplifier circuit 39 are not limited to being arranged inside the drive circuit IC 30, but may be mounted on a substrate. In addition, the determination unit 25 is not limited to being arranged inside the microcomputer 20, but may be composed of a logic circuit on a substrate.

[0087] (c) Multiplexer 38 may not be provided on the output side of voltage dividing points Du, Dv, Dw of each phase, and amplifier circuit 39 may be provided for each phase. In this case, multiplexer 38 may be provided on the output side of amplifier circuit 39 of each phase and the monitoring terminal may be shared.

[0088] (d) The upper and lower arm elements 61 to 66 and the motor relays 71, 72, 73 are not limited to MOSFETs, but may be formed of other semiconductor switching elements. For example, a freewheeling diode connected in parallel with a bipolar transistor is considered to be an element equivalent to a parasitic diode in a MOSFET.

[0089] (e) The abnormality detection device disclosed in the present invention may also be a dual-system structure applied to a multi-phase motor having two sets of multi-phase windings, as disclosed in Patent Document 1. The multi-phase motor is not limited to a three-phase motor, but may be a motor with four or more phases. In addition, the multi-phase motor is not limited to a steering assist motor of an electric power steering device, but may be a motor for other purposes.

[0090] As described above, the present disclosure is not limited to the above-described embodiments, and can be implemented in various forms within the scope not departing from the gist of the present disclosure.

[0091] The invention regarding "an abnormality detection device, further comprising: a plurality of motor relays, the plurality of motor relays being arranged in a motor current path connecting the inter-arm connection points of each phase of the inverter with the each phase winding of the multi-phase motor, and being connected in parallel with a parasitic diode that conducts the current flowing from one side of the inverter to the multi-phase motor side, the plurality of motor relays cutting off the current flowing from one side of the multi-phase motor to one side of the inverter when disconnected; and a motor relay drive circuit that outputs a selection signal to the motor relay, the determination unit detecting the connection adhesion abnormality and disconnection adhesion abnormality of the motor relay of the target phase based on the voltage at the voltage dividing point when the leakage current flows." and the invention regarding "an abnormality detection device, the determination unit detecting the connection adhesion abnormality of the upper arm element in a state where the operation of the upper arm element drive circuit is stopped." can also be combined.

[0092] The abnormality detection device and its method described in the present disclosure can be implemented by a special-purpose computer, which is provided by a processor and a memory programmed in a manner to perform one or more functions embodied by a computer program. Alternatively, the abnormality detection device and its method described in the present disclosure can also be implemented by a special-purpose computer, which is provided by a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the abnormality detection device and its method described in the present disclosure can also be implemented by one or more special-purpose computers, which are composed of a combination of a processor and a memory programmed in a manner to perform one or more functions and a processor composed of one or more hardware logic circuits. In addition, the computer program can be stored as an instruction executed by a computer in a non-transient tangible storage medium that can be read by the computer.

[0093] The present disclosure is described based on the implementation mode. However, the present disclosure is not limited to the implementation mode and structure. The present disclosure also includes various modifications and variations within the scope of equality. In addition, various combinations and methods, and other combinations and methods that further include only one element, above or below it, are also included in the scope and scope of thought of the present disclosure.

Claims

1. An abnormality detection device, characterized in that: have: An inverter (60) is formed by bridging a power line (Lp) and a ground line (Lg) connected to a battery (15) by upper arm elements (61, 62, 63) and lower arm elements (64, 65, 66) of a plurality of phases, and converts the DC power of the battery and supplies it to each phase winding (81, 82, 83) of a multi-phase motor (80); An upper arm element driving circuit (31, 32, 33) which outputs a gating signal to the upper arm element; a lower arm element driving circuit (34, 35, 36) which outputs a gating signal to the lower arm element; a plurality of pull-down resistors (Rdu, Rdv, Rdw), the plurality of pull-down resistors being composed of two voltage-dividing resistors provided for each phase for dividing the voltage between an inter-arm connection point (Nu, Nv, Nw) and ground, connecting the inter-arm connection point, which is a connection point between the upper arm element and the lower arm element of each phase, to ground; and a determination unit (25) for detecting an abnormality of at least the upper arm element and the lower arm element based on a voltage at a voltage dividing point which is a connection point of the two voltage dividing resistors, The power line is connected to the inter-arm connection point of each phase without a pull-up resistor. The determination unit detects an ON-sticking abnormality and an OFF-sticking abnormality of the upper arm element and the lower arm element based on a voltage at the voltage dividing point when a leakage current flows from the upper arm element drive circuit to ground via the pull-down resistor during operation of the upper arm element drive circuit.

2. The abnormality detection device according to claim 1, characterized in that: The determination unit detects an on-stick abnormality of the upper arm element in a state where the operation of the upper arm element driving circuit is stopped.

3. The abnormality detection device according to claim 1, characterized in that: Also available: A plurality of motor relays (71, 72, 73), which are arranged in a motor current path connecting the inter-arm connection points of each phase of the inverter with the windings of each phase of the multi-phase motor, and are connected in parallel with parasitic diodes that conduct the current flowing from one side of the inverter to one side of the multi-phase motor, and the plurality of motor relays cut off the current flowing from one side of the multi-phase motor to one side of the inverter when disconnected; as well as a motor relay driving circuit (371, 372, 373), which outputs a selection signal to the motor relay, The determination unit detects an ON-sticking abnormality and an OFF-sticking abnormality of the motor relay of the target phase based on the voltage at the voltage dividing point when the leakage current flows.

4. The abnormality detection device according to claim 3, characterized in that: The multi-phase motor is a three-phase motor, and the voltages of the voltage dividing points in two phases other than the target phase are used as monitoring phases for one phase or two phases for abnormality detection by the determination unit. The determination unit detects the connection sticking abnormality and disconnection sticking abnormality of the motor relay of the target phase based on the voltage at the voltage dividing point of the monitoring phase when the leakage current flows, in a state in which the upper arm elements of all phases and the lower arm elements of two phases other than the target phase are disconnected, the lower arm element of the target phase is connected, and the motor relay of at least the phase other than the target phase and the monitoring phase is disconnected.

5. The abnormality detection device according to claim 4, characterized in that: The determination unit detects an ON-sticking abnormality and an OFF-sticking abnormality of the motor relay of the target phase based on the voltage of the voltage dividing point of the monitoring phase when the leakage current flows in a state where the motor relay of the monitoring phase is turned on.

6. The abnormality detection device according to any one of claims 1 to 5, characterized in that: The pull-down resistor is provided inside a drive circuit IC (30) in which the upper arm element drive circuit is built.

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