Drive device, motor, actuator, and abnormality determination method

Abstract

To provide a drive device and related others. capable of determining an abnormality in an inrush prevention circuit.SOLUTION: A drive device 1 that generates drive power for an electric motor 102 on the basis of power supplied from an external power source 20 includes: an inverter 33 that generates drive power; an inrush prevention circuit 31 provided between the external power source 20 and the inverter 33; a power supply switch 21 interposed between the external power source 20 and the inrush prevention circuit 31; a main power supply control unit 43 that controls operation of the power supply switch 21; and at least one of a current detection unit 37 and an inrush prevention circuit voltage detection unit 38. In response to an abnormality in the inrush prevention circuit 31 determined on the basis of at least one of a current detected by the current detection unit 37 and a voltage detected by the inrush prevention circuit voltage detection unit 38, the main power supply control unit 43 makes the power supply switch 21 non-conductive.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a drive device, a motor, an actuator, and an abnormality determination method. [Background technology]

[0002] A configuration is known in which an inrush prevention circuit is provided to suppress inrush current from an external power source to a drive device for an electric motor (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-107892 A Summary of the Invention [Problem to be solved by the invention]

[0004] If an abnormality occurs in the inrush current prevention circuit, problems such as an inrush current cannot be suppressed and excessive current flows through downstream circuit elements may occur, resulting in a state in which power supply from an external power source to the motor drive device should not be continued. However, the conventional configuration does not have a mechanism for determining an abnormality in the inrush current prevention circuit.

[0005] An object of the present invention is to provide a drive device, a motor, an actuator, and an abnormality determination method that are capable of determining an abnormality in an inrush prevention circuit. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the drive device of the present invention is a drive device that generates drive power for an electric motor based on power supplied from an external power source, and includes a power generation unit that generates the drive power, an electrical resistance provided in a current transmission path between the external power source and the power generation unit, and a first switch that is provided in parallel with the electrical resistance with respect to the transmission path and is switchable between conductive and non-conductive states, and includes an inrush prevention circuit that suppresses inrush current from the external power source, a second switch that is interposed between the external power source and the inrush prevention circuit and is switchable between on and off of the supplied power, a first control unit that controls the operation of the first switch, a second control unit that controls the operation of the second switch, and at least one of a current detection unit that detects a current between the inrush prevention circuit and the power generation unit, and a first voltage detection unit that detects a voltage between two points of the transmission path sandwiching the inrush prevention circuit, and the second control unit makes the second switch non-conductive in response to an abnormality in the inrush prevention circuit determined based on at least one of the current detected by the current detection unit and the voltage detected by the first voltage detection unit.

[0007] Therefore, it is possible to determine whether an abnormality has occurred in the inrush prevention circuit based on at least one of the current between the inrush prevention circuit and the power generation unit and the voltage between two points on the transmission line sandwiching the inrush prevention circuit. Moreover, when it is determined that such an abnormality has occurred, the second switch is made non-conductive, thereby stopping the power supply from the external power source.

[0008] The driving device of the present invention is provided with the current detection unit, and the first switch is controlled to be in a non-conductive state before the supply power is switched from an off state to an on state, and the current detection unit compares the current after the supply power is switched from an off state to an on state with a first threshold value to determine whether an abnormal short circuit has occurred in the first switch, and the second control unit makes the second switch non-conductive when it is determined that an abnormal short circuit has occurred in the first switch.

[0009] Therefore, based on the comparison result between the current after the supply power is switched from an off state to an on state and the first threshold value, it can be determined whether an abnormal short circuit has occurred in the first switch of the inrush prevention circuit, which should be controlled to be non-conductive before the supply power is switched from an off state to an on state, and if it is determined that such an abnormal short circuit has occurred, the second switch can be made non-conductive to stop the power supply from the external power source.

[0010] In the driving device of the present invention, the current detection unit compares the current after the supply power is switched from an off state to an on state with a second threshold value to determine whether a break has occurred between the transmission path and the electrical resistance, and the second control unit makes the second switch non-conductive if it is determined that the break has occurred.

[0011] Therefore, since the first switch is controlled to be in a non-conductive state before the supply power is switched from an off state to an on state, the transmission path of the current flowing from the external power source to the power generation unit includes an electric resistance. Here, by comparing the current after the supply power is switched from an off state to an on state with the second threshold value, it is possible to detect a disconnection between the transmission path and the electric resistance. In other words, if such a disconnection occurs, the current does not substantially pass through the transmission path and is not detected by the current detection unit, so it is possible to determine whether a disconnection has occurred based on the current. Then, when it is determined that such a disconnection has occurred, it is possible to stop the power supply from the external power source by making the second switch non-conductive.

[0012] The driving device of the present invention includes a third control unit that controls the operation of the power generating unit in response to an external input of a signal including a command regarding the operation of the electric motor, and the first voltage detection unit, wherein the first switch is controlled to be in a conductive state during operation control of the power generating unit by the third control unit, and the first voltage detection unit compares the voltage detected during operation control of the power generating unit by the third control unit with a third threshold value to determine whether an abnormality has occurred that causes the first switch to be no longer in a conductive state, and when it is determined that an abnormality has occurred that causes the first switch to be no longer in a conductive state, the second control unit makes the second switch non-conductive.

[0013] Therefore, since the first switch is controlled to be in a conductive state during the operation control of the power generating unit by the third control unit, the transmission path of the current flowing from the external power source to the power generating unit during such operation control should prioritize the conductive first switch over electrical resistance. Therefore, if an abnormality occurs in which the first switch does not become conductive, it is possible to determine whether such an abnormality has occurred from the voltage detected during the operation control of the power generating unit by the third control unit, using as a reference the voltage that should have passed through the conductive first switch during such operation control. Then, if it is determined that such an abnormality has occurred, the second switch can be made non-conductive to stop the power supply from the external power source.

[0014] In the driving device of the present invention, the power generating unit includes a converter that generates a DC current based on power supplied from the external power source, which is an AC power source, an inverter that converts the DC current into AC and supplies it to the motor, and a capacitor connected to a positive transmission path and a negative transmission path of a current between the converter and the inverter to smooth the DC current. The power generating unit is provided with a second voltage detection unit that detects a voltage between the positive transmission path and the negative transmission path, and the second voltage detection unit compares the voltage between the positive transmission path and the negative transmission path with a fourth threshold value to determine whether a break has occurred between the transmission path and the electrical resistance, and the second control unit makes the second switch non-conductive when it is determined that the break has occurred.

[0015] Therefore, since no voltage is generated between the positive transmission line and the negative transmission line when a disconnection occurs, it is possible to determine whether a disconnection has occurred between the transmission line and the electrical resistance by utilizing such an event. When it is determined that such a disconnection has occurred, the second switch is made non-conductive, thereby stopping the power supply from the external power source.

[0016] In order to achieve the above object, a motor according to the present invention includes the above-mentioned drive device and the electric motor.

[0017] Therefore, it is possible to determine whether an abnormality has occurred in the inrush prevention circuit in the motor drive device. Furthermore, if it is determined that an abnormality has occurred, the second switch is made non-conductive, thereby cutting off the power supply from the external power source.

[0018] In order to achieve the above object, an actuator of the present invention includes the above-mentioned motor, and a mechanism that is connected to the output shaft of the electric motor and operates in response to the rotational driving force of the electric motor.

[0019] Therefore, it is possible to determine whether an abnormality has occurred in the inrush prevention circuit in the drive device of the motor equipped in the actuator. Also, if it is determined that an abnormality has occurred, the second switch is made non-conductive, thereby cutting off the power supply from the external power source.

[0020] To achieve the above-mentioned object, the abnormality determination method of the present invention is an abnormality determination method for detecting an abnormality in an inrush prevention circuit that suppresses inrush current from an external power source in a drive device that generates drive power for an electric motor based on power supplied from the external power source, wherein the inrush prevention circuit has an electrical resistance provided in a current transmission path between the external power source and a power generation unit that generates the drive power, and a first switch that is provided in parallel with the electrical resistance on the transmission path and is capable of switching between conductive and non-conductive states, and determines an abnormality in the inrush prevention circuit based on the detection result of at least one of a current detection unit that detects the current between the inrush prevention circuit and the power generation unit, and a first voltage detection unit that detects the voltage between two points on the transmission path sandwiched between the inrush prevention circuit.

[0021] Therefore, an abnormality in the inrush prevention circuit can be determined based on at least one of the current between the inrush prevention circuit and the power generation unit and the voltage between two points on the transmission line sandwiching the inrush prevention circuit. Effect of the Invention

[0022] According to the present invention, an abnormality in an inrush prevention circuit can be determined. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram showing an example of the overall configuration of an apparatus according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing the main configuration of the drive device. [Diagram 3] FIG. 3 is a time chart showing an example of voltage waveforms and current waveforms in the drive device when no abnormality occurs, as well as on / off states of the power supply, short-circuit switch, servo, and motor. [Figure 4] FIG. 4 is a time chart showing an example of voltage waveforms and current waveforms in the drive device when a short circuit occurs, as well as on / off states of the power supply, short-circuit switch, servo, and motor. [Diagram 5] FIG. 5 is a time chart showing an example of voltage waveforms and current waveforms in a drive device when an open circuit fault occurs, as well as on / off states of a power supply, a short-circuit switch, a servo, and an electric motor. [Figure 6] FIG. 6 is a time chart showing an example of voltage waveforms and current waveforms in the drive device when a wire is broken, as well as on / off states of the power supply, short-circuit switch, servo, and motor. [Figure 7] FIG. 7 is a flowchart showing a process for determining an abnormality assumed in the embodiment as an abnormality related to the inrush prevention circuit. [Figure 8] FIG. 8 is a block diagram showing a main configuration of a drive device according to the first modification. [Figure 9] FIG. 9 is a block diagram showing a main configuration of a drive device according to the second modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The requirements of each embodiment described below can be appropriately combined. In addition, some components may not be used.

[0025] (Embodiment) 1 is a schematic diagram showing an example of the overall configuration of an apparatus according to an embodiment. An actuator 10 according to an embodiment includes a drive unit 100 and a drive device 1. The drive device 1 is communicably connected to a host device 40 that is located above the actuator 10. The actuator 10 operates based on instructions from the host device 40.

[0026] The driving unit 100 outputs a predetermined thrust by power transmission from an electric motor 102 that operates based on the control of the driving device 1. In the embodiment, the driving unit 100 functions as a mechanism that is connected to the output shaft of the electric motor 102 and operates according to the rotational driving force of the electric motor 102. The electric motor 102 performs a rotational operation based on a current input from the driving device 1.

[0027] A reducer 104 for transmitting the rotational force of the electric motor 102 is provided inside the housing 101. The reducer 104 is connected to a linear motion mechanism 108, and the rotational force from the reducer 104 is transmitted to the linear motion mechanism 108. The output shaft 105 and the linear motion mechanism 108 are connected via a connecting mechanism 107. When the linear motion mechanism 108 rotates, the connecting mechanism 107 moves along the axial direction of the linear motion mechanism 108 (the direction indicated by the arrow A in FIG. 1), and the output shaft 105 also moves (piston action) in conjunction with this, so that a thrust force is output by the actuator 10. The moving directions of the output shaft 105 and the connecting mechanism 107 are determined according to the rotational direction of the electric motor 102.

[0028] The linear motion mechanism 108 is configured with a screw shaft having a helical screw groove on its outer circumferential surface. The connecting mechanism 107 is arranged by being fitted into the screw groove. At this time, a rolling element (not shown) included in the connecting mechanism 107 is configured to be able to roll freely in the screw groove of the linear motion mechanism 108, and the connecting mechanism 107 moves in a predetermined direction as the linear motion mechanism 108 rotates. A lubricant (lubricating oil, grease, etc.) may be supplied around the rolling element and the screw groove by any lubrication method to reduce friction therebetween.

[0029] The external power supply 20 is a power supply provided outside the drive device 1. In the embodiment, the external power supply 20 is an AC power supply. The power supply switch 21 is a switch provided to be capable of switching between conduction and non-conduction between the external power supply 20 and a main power supply unit 30 (see FIG. 2) of the drive device 1.

[0030] 2 is a block diagram showing the main configuration of the drive device 1. Note that the motor 90 refers to a configuration including the drive device 1 and an electric motor 102. The drive device 1 includes a main power supply unit 30, an inverter control unit 41, an inrush prevention control unit 42, a main power supply control unit 43, and a DC link voltage detection unit 44. The main power supply unit 30 includes an inrush prevention circuit 31, a converter 32, an inverter 33, a capacitor 36, a current detection unit 37, and an inrush prevention circuit voltage detection unit 38.

[0031] The inrush prevention circuit 31 includes an inrush prevention resistor 31a and a short-circuit switch 31b. The inrush prevention resistor 31a is a resistor provided in series with one of the first transmission line 22 and the second transmission line 23 (for example, the first transmission line 22) that connect the power supply switch 21 and the converter 32. In the embodiment, the inrush prevention resistor 31a functions as an electric resistance provided in the transmission line (for example, the first transmission line 22) of the current between the external power supply 20 and the inverter 33. The short-circuit switch 31b is a switch provided in parallel with the inrush prevention resistor 31a with respect to the first transmission line 22 and capable of switching between conduction and non-conduction. In the embodiment, the short-circuit switch 31b functions as a first switch provided in parallel with the electric resistance (inrush prevention resistor 31a) with respect to the transmission line (for example, the first transmission line 22) and capable of switching between conduction and non-conduction.

[0032] 2, the power supply switch 21 is provided between the external power supply 20 and the inrush prevention circuit 31 so as to be capable of switching on / off the power supply from the external power supply 20. Therefore, the power supply switch 21 in the embodiment functions as a second switch.

[0033] The converter 32 converts AC power supplied from the external power supply 20 into DC power. Therefore, it can be said that the converter 32 of the embodiment generates a DC current based on the power supplied from the external power supply 20, which is an AC power supply. The converter 32 is configured with, for example, a diode rectifier circuit, but is not limited to this and may have another configuration that functions in a similar manner.

[0034] The inverter 33 converts the DC power supplied from the converter 32 into AC power. The inverter 33 is configured to include, for example, switching elements, and functions by each switching element being PWM-controlled by the inverter control unit 41, but is not limited thereto, and may have another configuration that functions in a similar manner.

[0035] In the embodiment, the power supplied to the electric motor 102 is power converted by the inverter 33. In the embodiment, the electric motor 102 is, for example, a three-phase AC induction motor, but is not limited thereto, and the specific form of the output by the inverter 33 may be any form that corresponds to the specific form of the electric motor 102. The inverter 33 in the embodiment functions as a power generating unit that generates drive power for the electric motor 102 based on power supplied from the external power source 20.

[0036] The capacitor 36 is connected in parallel with the converter 32 and the inverter 33 across the positive transmission line 34 and the negative transmission line 35 that connect the converter 32 and the inverter 33. The capacitor 36 smoothes the current and voltage due to the power supplied from the converter 32 to the inverter 33.

[0037] The current detection unit 37 is connected to one point on the first transmission line 22 that is closer to the converter 32 than the inrush prevention circuit 31, detects the current flowing through the first transmission line 22 at that point, and outputs information indicating the magnitude of the current to the main power supply control unit 43. Hereinafter, the term "current detection unit current" refers to the current detected by the current detection unit 37. In the embodiment, the current detection unit 37 functions as a current detection unit that detects the current between the inrush prevention circuit 31 and the power generation unit (inverter 33).

[0038] The inrush prevention circuit voltage detection unit 38 detects the voltage between two points of the first transmission line 22 sandwiching the inrush prevention circuit 31, and outputs information indicating the level of the voltage to the main power supply control unit 43. Specifically, the inrush prevention circuit voltage detection unit 38 detects the voltage between a point on the first transmission line 22 closer to the power supply switch 21 than the inrush prevention circuit 31 as one of the two points, and a point on the first transmission line 22 closer to the converter 32 than the inrush prevention circuit 31 as the other of the two points. In the embodiment, the one point at which the current detection unit 37 detects the current is closer to the converter 32 than the other point. Hereinafter, when the inrush prevention circuit voltage is described, it refers to the voltage detected by the inrush prevention circuit voltage detection unit 38. In the embodiment, the inrush prevention circuit voltage detection unit 38 functions as a first voltage detection unit that detects the voltage between two points of a transmission line (for example, the first transmission line 22) sandwiching the inrush prevention circuit 31.

[0039] The higher-level device 40 is a device that outputs a signal that functions as a command to put the main power supply unit 30 into either a servo-on state or a servo-off state to the inverter control unit 41 in response to a manual input by a human or a signal input from an external device. The servo-on state is a state of the main power supply unit 30 in which the motor 102 can be driven (operation preparation completed state). The servo-off state is a state of the main power supply unit 30 that is not in the servo-on state, that is, a state in which the motor 102 cannot be driven (operation preparation not completed state). Hereinafter, when a servo-on signal is described, it refers to a signal that functions as a command to put the motor 102 into the servo-on state. Also, when a servo-off signal is described, it refers to a signal that functions as a command to put the motor 102 into the servo-off state.

[0040] The inverter control unit 41 performs various processes related to the operation control of the electric motor 102 under the control of the higher-level device 40. Specifically, the inverter control unit 41 switches between a servo-on state and a servo-off state under the control of the higher-level device 40. When a servo-on signal is input, the inverter control unit 41 performs control to make the inverter 33 supply AC power to realize the operation command content of the electric motor 102 from the higher-level device 40, in response to the operation command content of the electric motor 102. Such control is, for example, a PWM switching operation in the inverter 33. In the embodiment, the inverter control unit 41 functions as a third control unit that controls the operation of the power generation unit (inverter 33) in response to an input from the outside (higher-level device 40) of a signal including a command related to the operation of the electric motor 102.

[0041] Furthermore, the inverter control unit 41 operates the inrush prevention control unit 42 and the main power supply control unit 43 so as to perform "power supply from the external power supply 20 to the converter 32", which is a prerequisite for the AC power supply.

[0042] The inrush prevention control unit 42 switches and controls the current transmission path in the inrush prevention circuit 31. Specifically, the inrush prevention control unit 42 controls whether the short-circuit switch 31b is in a conductive state or a non-conductive state by controlling the on / off of the short-circuit switch 31b. When the short-circuit switch 31b is in a conductive state, the current transmission path in the inrush prevention circuit 31 includes the short-circuit switch 31b. When the short-circuit switch 31b is in a non-conductive state, the current transmission path in the inrush prevention circuit 31 includes the inrush prevention resistor 31a.

[0043] When the short-circuit switch 31b is turned off (non-conductive state), the power supplied from the external power supply 20 is supplied to the converter 32 via the inrush prevention resistor 31a. This makes it possible to suppress an inrush current from flowing from the external power supply 20 to the converter 32. Hereinafter, when simply referred to as an inrush current, this refers to an inrush current from the external power supply 20 to the converter 32 in the embodiment. The inrush current is converted to DC by the converter 32 and reaches the inverter 33, so it can be said to also function as an "inrush current to the inverter 33". On the other hand, when the short-circuit switch 31b is turned on (conductive state), both ends of the inrush prevention resistor 31a are short-circuited, and substantially no power loss occurs due to the inrush prevention resistor 31a.

[0044] The main power supply control unit 43 performs on / off control of the power supply switch 21 based on the output from the inrush prevention control unit 42. When the power supply switch 21 is in a conductive state, unless there is an abnormality, power is supplied from the external power supply 20 to the main power supply unit 30, thereby generating the power necessary for the operation of the electric motor 102. When the power supply switch 21 is in a non-conductive state, the power necessary for the operation of the electric motor 102 is not generated.

[0045] In addition, under the control of the inverter control unit 41 according to the servo-on signal, the short-circuit switch 31b is controlled to be in the OFF state before the power supply switch 21 is turned on. For example, the short-circuit switch 31b may be configured as a normally open contact. The normally open contact here refers to a mode in which the short-circuit switch 31b is in the OFF state unless the inrush prevention control unit 42 actively turns the short-circuit switch 31b to the ON state. If it is a normally open contact, the short-circuit switch 31b can be maintained in the OFF state when power is not being supplied to the inrush prevention control unit 42, so that the short-circuit switch 31b can be configured to be maintained in the OFF state from the beginning at the time of input of the servo-on signal. Alternatively, since the power supply to the inrush prevention control unit 42 and the power supply to the main power supply unit 30 are performed independently, for example, the power supply to the main power supply unit 30 may be configured to be started when the inrush prevention control unit 42 has started up and is in a state in which the short-circuit switch 31b can be controlled to be turned on and off, and the inrush prevention control unit 42 may start supplying power to the main power supply unit 30 after controlling the short-circuit switch 31b to the OFF state as an initial setting process after startup.

[0046] In FIG. 1, the inrush prevention control unit 42 is interposed in the command transmission path from the inverter control unit 41 to the main power supply control unit 43. However, in the case of a normally open contact, for example, a direct command transmission path may be provided from the inverter control unit 41 to the main power supply control unit 43.

[0047] The main power supply control unit 43 also performs operation control to switch the state of the power supply switch 21 based on the outputs from the current detection unit 37, the inrush prevention circuit voltage detection unit 38, and the DC link voltage detection unit 44. Such operation control is, for example, operation control that responds to an abnormality in the inrush prevention circuit 31. The abnormality in the inrush prevention circuit 31 will be described in detail later.

[0048] The DC link voltage detection unit 44 is connected to the positive transmission line 34 and the negative transmission line 35 so as to be in parallel with the converter 32, the inverter 33, and the capacitor 36, detects the voltage between the positive transmission line 34 and the negative transmission line 35 (DC link voltage), and outputs information indicating the voltage to the main power supply control unit 43. Hereinafter, the DC link voltage refers to the voltage detected by the DC link voltage detection unit 44. Note that the position at which the DC link voltage detection unit 44 is connected to the positive transmission line 34 and the negative transmission line 35 is closer to the inverter 33 than the capacitor 36.

[0049] In the embodiment, as described above, the inrush current can be suppressed by the inrush prevention circuit 31. Specifically, the inrush prevention circuit 31 controls the on / off of the short-circuit switch 31b in accordance with the DC link voltage, whether the servo is on, and a predetermined DC link voltage threshold value used for controlling the short-circuit switch 31b, thereby suppressing the inrush current and reducing the power loss after the suppression of the inrush current at the same time.

[0050] In the embodiment, at least a main threshold value Vth1 is set as the threshold value of the DC link voltage. The main threshold value Vth1 is a threshold value for determining whether the power supply switch 21 is in an on state and power is being supplied to the main power supply unit 30. The main threshold value Vth1 is set to, for example, about 90% of the stable output value of the DC link voltage in a state in which power is being stably supplied to the main power supply unit 30.

[0051] For example, when the stable output value of the DC link voltage is 254 VDC (=180 VAC×21 / 2), the main threshold Vth1 is set to about 228 VDC (=254 VDC×0.9).

[0052] Regarding the on / off control of the power supply switch 21 and the inrush prevention circuit 31 under normal conditions and the operation of each component related thereto, the control pattern in the drive device 1 when there is no abnormality will be described with reference to Fig. 3. Fig. 3 is a time chart showing an example of voltage waveforms and current waveforms in the drive device 1 when there is no abnormality, as well as on / off of the power supply, short-circuit switch 31b, servo, and electric motor 102.

[0053] 3 and later-described FIGS. 4, 5, and 6, from the top, the DC link voltage detected by the DC link voltage detection unit 44, the voltage (inrush prevention circuit voltage) detected by the inrush prevention circuit voltage detection unit 38, the current (current detection unit current) detected by the current detection unit 37, the on / off of the power supply, the on / off of the short-circuit switch 31b, the on / off of the servo, and the on / off of the electric motor 102 are shown. For the on / off of the power supply, the short-circuit switch 31b, the servo, and the electric motor 102, "H" indicates the on state, and "L" indicates the off state. The on / off of the power supply indicates the on (conductive state) / off (non-conductive state) of the power supply switch 21. The on / off of the servo indicates the servo on state (on: H) / servo off state (off: L). The on / off of the electric motor 102 indicates, for example, the execution (on) of a PWM switching operation in the inverter 33 by the inverter control unit 41 / non-execution (off) of the PWM switching operation.

[0054] When the servo-on signal is input to the inverter control unit 41, the inrush prevention control unit 42 and the main power supply control unit 43 start operating, and the power supply switch 21 is turned on under the condition that the short-circuit switch 31b is turned off. In the embodiment, the above-mentioned normally open contact is employed, so that it is sufficient to only turn the power supply switch 21 on. When the power supply switch 21 is turned on, power is supplied from the external power supply 20 to the main power supply unit 30. As a result, the DC link voltage rises to a stable output value exceeding the main threshold value Vth1, as in the period from timing t1 to timing t2 in FIG. 3. After the start of such power supply, the inrush prevention control unit 42 compares the DC link voltage detected by the DC link voltage detection unit 44 with the main threshold value Vth1, and when the DC link voltage becomes equal to or higher than the main threshold value Vth1, it determines that the servo-on state is established, and switches the short-circuit switch 31b of the inrush prevention circuit 31 from the off state to the on state.

[0055] In other words, after starting operation, the inrush prevention control unit 42 maintains the short-circuit switch 31b of the inrush prevention circuit 31 in the OFF state during the period in which the DC link voltage is less than the main threshold Vth1. That is, during this period, the current passes through the inrush prevention resistor 31a, thereby suppressing the inrush current. Then, by turning on the short-circuit switch 31b after the servo-on state is established, the power loss in the servo-on state is reduced.

[0056] It should be noted that, prior to timing t2 in FIG. 3 , there is a period of time during which the DC link voltage is equal to or greater than the main threshold value Vth1. The servo-on state may be established when the DC link voltage is equal to or greater than the main threshold value Vth1 for such a period of time, or the servo-on state may be established when the DC link voltage becomes equal to or greater than the main threshold value Vth1 after input of the servo-on signal.

[0057] After the servo is turned on at timing t2, the inverter control unit 41 starts a PWM switching operation in the inverter 33. This allows the motor 102 to be driven with a stable power supply. Note that specific operating modes such as the rotation direction of the motor 102 correspond to commands from the higher-level device 40.

[0058] In Fig. 3, during the period from timing t3 after timing t2 to timing t4, the inverter 33 performs a PWM switching operation. Accordingly, the DC link voltage and the current detection unit current fluctuate. Such fluctuations are normal and are associated with the PWM switching operation.

[0059] During the period from timing t2 to timing t3 and the period from timing t4 to timing t5, the servo is on but no PWM switching operation is performed. This is because the host device 40 does not output an operation command to the motor 102, and is normal.

[0060] When a servo-off signal is input to the inverter control unit 41 after the servo-on state is reached, the inverter control unit 41 transitions to a state in which it causes the main power supply control unit 43 to turn off the power supply switch 21. This causes the power supply from the external power supply 20 to the main power supply unit 30 to be cut off.

[0061] In Fig. 3, a servo-off signal is input to the inverter control unit 41 at timing t5, and the inverter control unit 41 transitions to the servo-off state from timing t5. Thereafter, the power supply switch 21 is turned off at timing t6, and the DC link voltage drops from timing t6 onwards. In this embodiment, when the inverter control unit 41 enters the servo-off state, the operations of the inrush prevention control unit 42 and the main power supply control unit 43 also end, and the short-circuit switch 31b is turned off. In the example shown in Fig. 3, the short-circuit switch 31b of the inrush prevention circuit 31 is switched to the off state from timing t7 when the DC link voltage becomes equal to or lower than the auxiliary threshold value Vth2.

[0062] The above describes the case where the inrush prevention circuit 31 operates normally. In the embodiment, further, a mechanism is provided for quickly cutting off the power supply from the external power source 20 to the main power supply unit 30 even if an abnormality occurs in the inrush prevention circuit 31. Hereinafter, such a mechanism will be described with reference to Figs. 4 to 6.

[0063] First, a case will be described in which the short-circuit switch 31b does not turn off and is always on. The cause of such a short-circuit is, for example, an unintended short circuit caused by an abnormality in the open / close contacts of the short-circuit switch 31b.

[0064] FIG. 4 is a time chart showing an example of the voltage waveform and current waveform in the drive device 1 and the on / off of the power supply, the short-circuit switch 31b, the servo, and the electric motor 102 when a short circuit occurs. As explained with reference to FIG. 3, in normal operation, when a servo-on signal is input to the inverter control unit 41, the inrush prevention control unit 42 and the main power control unit 43 start operating, and the power supply switch 21 is turned on under the condition that the short-circuit switch 31b is turned off. In contrast, when a short circuit occurs, the short-circuit switch 31b does not turn off, and the power supply switch 21 is turned on under the condition that the short-circuit switch 31b is turned on. This is indicated by "H" in the "Short-circuit switch" column between timing t11 and timing t12 in FIG. 4. The current in the current detection unit when such a short circuit occurs has a larger fluctuation range up and down than when normal.

[0065] Specifically, the current detection section current during the period from timing t1 to timing t2 in the normal state shown in FIG. 3 is equal to or exceeds the upper limit of the inrush current I R th2 and inrush current lower limit -I R th2. On the other hand, the current detection unit current during the period from timing t11 to timing t12 when a short circuit occurs as shown in FIG. R th2, and the inrush current lower limit -I R The current fluctuates widely enough that it sometimes falls below th2.

[0066] The current detection unit 37 has a function of judging whether or not a short circuit has occurred based on the amplitude of the current detected by the current detection unit. R th2 and inrush current lower limit -I RAt least one of th1, th2, and th3 is preset, and when a current detection unit current with an amplitude exceeding this is obtained, the current detection unit 37 determines that a short circuit has occurred and outputs to the main power supply control unit 43 according to the determination result. The main power supply control unit 43 that receives the output turns off the power supply switch 21. This cuts off the power supply from the external power supply 20 to the main power supply unit 30, as shown by "L" in the "Power supply" column after timing t12 in FIG. 4. In this way, according to the embodiment, even if a short circuit has occurred, the power supply from the external power supply 20 to the main power supply unit 30 is quickly cut off, and it is possible to suppress the occurrence of adverse effects (e.g., failure, etc.) caused by inrush current due to the drive device 1 continuing to operate with the short circuit occurring.

[0067] In the embodiment, the inrush current upper limit I R th2 and inrush current lower limit -I R th2 are set, and if at least one or both are exceeded, it is considered a short circuit. R th2 and inrush current lower limit -I R If at least one of the thresholds th1 and th2 is set, it is possible to realize a determination substantially similar to that of the embodiment.

[0068] If the main power supply voltage value is Vi and the resistance value of the inrush current prevention resistor 31a is R, the current value IR detected by the current detection unit under normal conditions is expressed as Vi / R. Therefore, a positive current value equal to or greater than the upper limit of Vi / R assumed under normal conditions is defined as the inrush current upper limit I R th2. Also, the lower limit of the inrush current -I R th2 is the upper limit of inrush current I R th2 may be set to a value opposite in sign to the inrush current upper limit I R th2 and inrush current lower limit -I R th2 functions as a first threshold for detecting an abnormal short circuit of the first switch.

[0069] Next, a case where an abnormality (open fault) occurs in which the short-circuit switch 31b does not turn on and always turns off will be described. Examples of causes of the open fault include malfunction of the short-circuit switch 31b, a fault in the signal transmission path from the main power supply control unit 43 to the short-circuit switch 31b, or a break in the connection path between the short-circuit switch 31b and the first transmission path 22.

[0070] Fig. 5 is a time chart showing an example of voltage waveforms and current waveforms in the driving device 1 when an open circuit fault occurs, and on / off of the power supply, the short-circuit switch 31b, the servo, and the electric motor 102. Events occurring in the period from timing t21 to timing t23 in the time chart shown in Fig. 5 are similar to events occurring in the period from timing t1 to timing t3 in the normal state in the time chart shown in Fig. 3, except that the "short-circuit switch" column is fixed at "L" due to the open circuit fault.

[0071] 5, the inverter 33 performs a PWM switching operation from timing t23, and when a PWM switching operation related to an open circuit fault is performed, the DC link voltage during the PWM switching operation becomes lower than normal because the inrush prevention resistor 31a is included in the power supply path from the external power supply 20. Furthermore, when an open circuit fault occurs, the swing width of the inrush prevention circuit voltage during the PWM switching operation becomes larger than normal.

[0072] Specifically, the inrush current prevention circuit voltage during the period from timing t3 to timing t4 in the normal state shown in FIG. 3 is constant and does not substantially fluctuate. On the other hand, the inrush current prevention circuit voltage during the period from timing t23 to timing t24 in the event of an open circuit fault shown in FIG. 5 is constant relative to the PWM variable voltage upper limit V R th1, and the PWM fluctuation voltage lower limit -V R The voltage fluctuates widely enough that it sometimes falls below th1.

[0073] The inrush current prevention circuit voltage detection unit 38 has a function of determining whether or not an open circuit fault has occurred based on the amplitude of the inrush current prevention circuit voltage. R th1 and PWM fluctuation voltage lower limit -V R At least one of th1 and th2 is preset, and when an inrush prevention circuit voltage with a swing exceeding the threshold voltage is obtained, the inrush prevention circuit voltage detection unit 38 determines that an open circuit failure has occurred and outputs to the main power supply control unit 43 according to the determination result. The main power supply control unit 43 that receives the output turns off the power supply switch 21. This cuts off the power supply from the external power supply 20 to the main power supply unit 30, as shown by "L" in the "Power supply" column after timing t24 in FIG. 5. Thus, according to the embodiment, even if an open circuit failure occurs, the power supply from the external power supply 20 to the main power supply unit 30 is quickly cut off, and adverse effects (such as a shortage of power supply to the electric motor 102) caused by the drive device 1 continuing to operate while the open circuit failure remains can be suppressed.

[0074] If the on-resistance of the short-circuit switch 31b in the servo-on state is Ron, and the current flowing through the first transmission line 22 in the servo-on state due to power supply from the external power source 20 is I, the inrush prevention circuit voltage generated when PWM switching operation is performed normally is expressed as Ron×I, but because Ron is extremely low, the inrush prevention circuit voltage becomes substantially constant. In contrast, when current flows through the inrush prevention resistor 31a due to an open fault, the inrush prevention circuit voltage becomes R×I, which reflects the resistance value (R) of the inrush prevention resistor 31a. Therefore, taking into account the resistance value (R) and current (I) of the inrush prevention resistor 31a, R×I is the PWM fluctuation voltage upper limit V R The PWM fluctuation voltage upper limit V R th1. Also, the lower limit of the PWM voltage fluctuation -V R th1 is the upper limit of the PWM fluctuation voltage V R In this way, the PWM variable voltage upper limit V R th1 and PWM fluctuation voltage lower limit -V R Th1 functions as a third threshold value for detecting an abnormality in which the first switch is no longer in a conductive state.

[0075] Next, a description will be given of a case where a disconnection occurs between the inrush prevention resistor 31a and the first transmission line 22. Examples of causes of such a disconnection include poor soldering of the inrush prevention resistor 31a. Hereinafter, when simply referring to a disconnection, it refers to a disconnection between the inrush prevention resistor 31a and the first transmission line 22 unless otherwise specified.

[0076] 6 is a time chart showing an example of the voltage waveform and current waveform in the drive device 1 when a wire is broken, and the on / off of the power supply, the short switch 31b, the servo, and the electric motor 102. R th1 and reference current lower limit -I R th1, the current detection section current exceeds the amplitude of the range defined by t31 and t32. On the other hand, the current detection section current during the period from timing t31 to timing t32 when the wire is broken, as shown in FIG. 6, is not substantially detected because no current flows through the first transmission line 22 due to the wire breakage. In this way, even though the power supply switch 21 is in the on state, the reference current upper limit I R th1 and reference current lower limit -I R When the current detection unit 37 does not obtain a current exceeding the amplitude of the range defined by th1 for a predetermined time or more, the current detection unit 37 determines that a break has occurred, and outputs to the main power supply control unit 43 according to the determination result. The main power supply control unit 43 that receives the output turns off the power supply switch 21. This cuts off the power supply from the external power supply 20 to the main power supply unit 30, as shown by "L" in the "Power supply" column after timing t32 in FIG. 6. In this way, according to the embodiment, even if a break has occurred, the power supply from the external power supply 20 to the main power supply unit 30 can be quickly cut off, and the continuation of unnecessary power supply can be suppressed.

[0077] In addition, the predetermined time for determining the disconnection, i.e., the reference current upper limit I R th1 and reference current lower limit -I R The time during which the current detection section current is not detected exceeding the range of amplitude specified by th1 and th2 is within the upper limit of the reference current I Rth1 and reference current lower limit -I R It is sufficient if the time is less than the time when the current detection unit current with an amplitude exceeding the range defined by th1 occurs and exceeds 0 seconds. More specifically, it is desirable to determine a predetermined time of an appropriate length based on prior measurement or simulation so as to have sufficient accuracy for determining disconnection. In this way, the reference current upper limit I R th1 and reference current lower limit -I R th1 functions as a second threshold for detecting a break in a current transmission path (eg, first transmission path 22) between the external power supply 20 and the power generating unit (inverter 33) and an electric resistance (inrush prevention resistor 31a).

[0078] As described above, a disconnection can be determined based only on the current detection unit current, but a disconnection can also be determined based on other factors besides the current detection unit current. For example, the DC link voltage is not substantially detected during a disconnection. Therefore, a method of determining a disconnection based on the continuation of a state in which the main threshold Vth1 is not exceeded after the power supply switch 21 is turned on may also be used. By determining a disconnection based on the current detection unit current and the DC link voltage, the accuracy of the determination can be further improved. In this case, the main threshold Vth1 functions as a fourth threshold for detecting a disconnection between a current transmission path (e.g., the first transmission path 22) between the external power supply 20 and the power generation unit (inverter 33) and an electric resistance (inrush prevention resistor 31a).

[0079] Fig. 7 is a flowchart showing the flow of main processing performed in the embodiment. Note that, before the start of the processing shown in Fig. 7, the servo is off and the power supply switch 21 is off.

[0080] When a servo-on signal is input (step S1), the short-circuit switch 31b is turned off (step S2). Note that, in the case of normally open contacts as described above, the state of step S2 may be established before the start of step S1. After the state of step S2 is established, the power supply switch 21 is turned on (step S3).

[0081] After the processing of step S3, the reference current upper limit I Rth1 and reference current lower limit -I R When a state is established in which the current detection unit current exceeding the amplitude of the range defined by th1 is not obtained for a predetermined time or longer (step S4; Yes), the current detection unit 37 determines that a break has occurred (step S5).

[0082] After the processing of step S3, the inrush current upper limit I R th2 and inrush current lower limit -I R When a state is established in which the current detection unit current having an amplitude exceeding at least one of th1 and th2 is obtained (step S6; Yes), the current detection unit 37 determines that a short circuit has occurred (step S7). The determinations in steps S4 and S6 may be performed in any order, or may be performed in parallel.

[0083] If the conditions in steps S4 and S6 are not satisfied after the process in step S3 (step S4: No and step S6: No), the DC link voltage rises to a stable output value exceeding the main threshold Vth1, and the servo-on state is entered (step S8). As a result of the process in step S8, the short-circuit switch 31b is turned on (step S9).

[0084] After the process of step S9, the PWM variable voltage upper limit V R th1 and PWM fluctuation voltage lower limit -V R When a state is established in which an inrush prevention circuit voltage having a swing exceeding at least one of th1 is obtained (step S10; Yes), the inrush prevention circuit voltage detection unit 38 determines that an open circuit abnormality has occurred (step S11).

[0085] If step S10 is not established (step S10; No), the states of steps S8 and S9 are maintained unless the operation of the electric motor 102 is terminated by an operation command from the higher-level device 40 (step S12; No). If the operation of the electric motor 102 is terminated by an operation command from the higher-level device 40 (step S12; Yes) or if any of the processes in steps S5, S7, or S11 has been performed, the power supply switch 21 is turned off (step S13).

[0086] As described above, according to this embodiment, the drive device 1 is a drive device that generates drive power for the electric motor 102 based on power supplied from the external power source 20, and includes a power generation unit (inverter 33) that generates the drive power, an electrical resistance (inrush prevention resistance 31a) provided in a current transmission path (e.g., the first transmission path 22) between the external power source 20 and the power generation unit, and a first switch (short-circuit switch 31b) that is provided in parallel with the electrical resistance on the transmission path and is switchable between conductive and non-conductive, and includes an inrush prevention circuit 31 that suppresses inrush current from the external power source 20, The power supply device includes a second switch (power supply switch 21) that is provided between the external power source 20 and the inrush prevention circuit 31 and is capable of switching on / off the power supply from the external power source 20, and "at least one of a first control unit (inrush prevention control unit 42) that controls the operation of the first switch, a second control unit (main power supply control unit 43) that controls the operation of the second switch, a current detection unit 37 that detects a current between the inrush prevention circuit 31 and the power generation unit, and a first voltage detection unit (inrush prevention circuit voltage detection unit 38) that detects a voltage between two points of the transmission line sandwiching the inrush prevention circuit 31." The second control unit makes the second switch non-conductive in response to an abnormality in the inrush prevention circuit 31 determined based on at least one of the current detected by the current detection unit 37 and the voltage detected by the first voltage detection unit.

[0087] Therefore, it is possible to determine whether an abnormality has occurred in the inrush prevention circuit 31 based on at least one of the current between the inrush prevention circuit 31 and the power generation unit (inverter 33) and the voltage between two points of a transmission line (for example, the first transmission line 22) sandwiching the inrush prevention circuit 31. Moreover, if it is determined that such an abnormality has occurred, the second switch (power supply switch 21) is made non-conductive, thereby stopping the power supply from the external power source 20.

[0088] In addition, the drive device 1 includes a current detection unit 37, and the first switch (short-circuit switch 31b) is controlled to be in a non-conductive state before the supply power from the external power source 20 is switched from an off state to an on state. The current detection unit 37 detects the current after the supply power is switched from the off state to the on state and a first threshold value (inrush current upper limit I R th2, etc.) to determine whether an abnormal short circuit has occurred in the first switch, and if it is determined that an abnormal short circuit has occurred in the first switch, the second control unit (main power supply control unit 43) makes the second switch (power supply switch 21) non-conductive.

[0089] Therefore, the current after the power supply from the external power source 20 is switched from the OFF state to the ON state and the first threshold value (inrush current upper limit I R th2, etc.), it can be determined that an abnormal short circuit has occurred in the first switch (short-circuit switch 31b) of the inrush prevention circuit 31, which should be controlled to be non-conductive before the supply power is switched from an off state to an on state, and if it is determined that such an abnormal short circuit has occurred, the second switch (power supply switch 21) is made non-conductive, thereby stopping the power supply from the external power source 20.

[0090] In addition, the current detection unit 37 detects the current after the power supply from the external power source 20 is switched from the OFF state to the ON state and the second threshold value (the reference current upper limit I R th1, etc.) to determine whether or not a break has occurred between the current transmission path between the external power source 20 and the power generating unit (inverter 33) and the electrical resistance (inrush prevention resistor 31a) of the inrush prevention circuit 31, and if it is determined that such a break has occurred, the second control unit (main power supply control unit 43) makes the second switch (power supply switch 21) non-conductive.

[0091] Therefore, since the first switch (short-circuit switch 31b) is controlled to be in a non-conductive state before the supply power from the external power source 20 is switched from an off state to an on state, the transmission path of the current flowing from the external power source 20 to the power generating unit (inverter 33) includes an electrical resistance (inrush prevention resistor 31a). Here, the current after the supply power is switched from an off state to an on state and the second threshold value (reference current upper limit I R th1, etc.), a break between the transmission path and the electrical resistance can be detected. That is, if such a break occurs, the current does not substantially pass through the transmission path and is not detected by the current detection unit, so it is possible to determine whether a break has occurred based on the current. Then, if it is determined that such a break has occurred, the second switch (power supply switch 21) is made non-conductive, thereby stopping the power supply from the external power source.

[0092] The inverter control unit 41 controls the operation of the power generating unit (inverter 33) in response to an input from the outside (higher device 40) of a signal including a command related to the operation of the electric motor 102, and includes a first voltage detection unit (inrush current prevention circuit voltage detection unit 38). The first switch (short-circuit switch 31b) is controlled to be in a conductive state during the operation control of the power generating unit by the third control unit (for example, PWM switching operation). The first voltage detection unit detects a voltage detected during the operation control of the power generating unit by the third control unit and a third threshold (PWM fluctuation voltage upper limit V R th1, etc.) to determine whether an abnormality (open abnormality) has occurred that causes the first switch to become non-conductive, and if it is determined that such an abnormality has occurred, the second control unit (main power supply control unit 43) makes the second switch (power supply switch 21) non-conductive.

[0093] Therefore, since the first switch (short-circuit switch 31b) is controlled to be in a conductive state during the operation control of the power generating unit (inverter 33) by the third control unit (inverter control unit 41), the transmission path of the current flowing from the external power source 20 to the power generating unit during the operation control should prioritize the first switch in a conductive state over the electrical resistance (inrush prevention resistor 31a). Therefore, if an abnormality occurs in which the first switch does not become conductive, it can be determined whether or not such an abnormality has occurred from the voltage detected during the operation control of the power generating unit by the third control unit, using the voltage that should have passed through the first switch in a conductive state during the operation control as a reference. Then, if it is determined that such an abnormality has occurred, the second switch (power supply switch 21) is made non-conductive, thereby stopping the power supply from the external power source 20.

[0094] The power generating unit (inverter 33) has a converter 32 that generates a DC current based on power supplied from external power source 20 which is an AC power source, an inverter 33 that converts the DC current into AC current and supplies it to the electric motor 102, and a capacitor 36 that is connected to a positive transmission line 34 and a negative transmission line 35 of a current between the converter 32 and the inverter 33 and smoothes the DC current. The driving device 1 has a second voltage detecting unit (DC link voltage detecting unit 44) that detects a voltage between the positive transmission line 34 and the negative transmission line 35. The second voltage detection unit compares the voltage between the positive transmission line 34 and the negative transmission line 35 with a fourth threshold value (main threshold value Vth1) to determine whether a break has occurred between the current transmission line (e.g., the first transmission line 22) and the electrical resistance (inrush prevention resistor 31a) between the external power source 20 and the power generation unit, and if such a break is detected, the second control unit (main power supply control unit 43) makes the second switch (power supply switch 21) non-conductive.

[0095] Therefore, since no voltage is substantially generated between the positive transmission line 34 and the negative transmission line 35 when a disconnection occurs, it is possible to determine whether a disconnection has occurred between the transmission line between the external power source 20 and the power generating unit (inverter 33) and the electrical resistance (inrush prevention resistor 31a) by utilizing such an event. When it is determined that such a disconnection has occurred, the second switch (power supply switch 21) is made non-conductive, thereby stopping the power supply from the external power source 20.

[0096] Modifications 1 and 2, which have a partial configuration different from that of the embodiment, will be described below with reference to Figs. 8 and 9. The configurations of Modifications 1 and 2 are the same as those of the embodiment except for the points to be noted below, and the same reference numerals are used in the drawings and the description is omitted. In the embodiment, the drive device 1 shown in Figs. 1 and 2 may be replaced with drive device 1A of Modification 1 shown in Fig. 8 or drive device 1B of Modification 2 shown in Fig. 9. Note that when the term "embodiment, etc." is used, it includes the embodiment, Modification 1, and Modification 2.

[0097] (Variation 1) Fig. 8 is a block diagram showing a main configuration of a drive device 1A according to Modification 1. As shown in Fig. 8, the inrush prevention circuit 31 may be provided in one of the positive transmission line 34 or the negative transmission line 35 (for example, the positive transmission line 34). Specifically, the inrush prevention resistor 31a of Modification 1 is connected in series on the transmission line that connects the converter 32 and the inverter 33 in the positive transmission line 34. Also, the short-circuit switch 31b of Modification 1 is connected in parallel with the inrush prevention resistor 31a to the positive transmission line 34.

[0098] In the first modification, the current detection unit 37 and the inrush prevention circuit voltage detection unit 38 are also connected to the same target (for example, the positive transmission line 34) as the inrush prevention circuit 31. As shown in Fig. 8, two points in the first modification, one being a connection point between the inrush prevention circuit 31 and the current detection unit 37 and the positive transmission line 34, and the other being a connection point between the inrush prevention circuit voltage detection unit 38 and the positive transmission line 34, are provided on the converter 32 side relative to the capacitor 36.

[0099] In addition, in the first modification, the current passing through the inrush prevention circuit 31 is converted to DC by the converter 32, so the inrush prevention circuit voltage and the current detection unit current illustrated with reference to Figs. 3 to 6 also have waveforms corresponding to DC. Therefore, the matter referred to as "the amplitude of the inrush prevention circuit voltage" in the embodiment is replaced with "the amplitude of the inrush prevention circuit voltage" in the first modification, and for example, the PWM variable voltage upper limit V R In addition, the item "swing width of the current detection unit current" in the embodiment is replaced with "magnitude of the current detection unit current" in the first modification. For example, the upper limit of the inrush current I R An upper threshold value corresponding to th2 is used.

[0100] (Variation 2) FIG. 9 is a block diagram showing a main configuration of the driving device 1B according to the second modification. As shown in FIG. 9, a notification unit 49 may be added to the configuration of the driving device 1 (see FIG. 2). When the power supply switch 21 is turned off due to a short circuit, an open circuit fault, or a disconnection, the notification unit 49 notifies the driver that an abnormality has occurred. The notification may be visual, audible, or any other method. For example, a light source indicating the occurrence of a short circuit, a light source indicating the occurrence of an open circuit fault, and a light source indicating the occurrence of a disconnection may be provided in the notification unit 49 separately, and the light source corresponding to the abnormality that has occurred may be turned on. Notification control by the notification unit 49 may be performed in response to an input of a signal indicating the occurrence of a short circuit, an open circuit fault, or a disconnection from any of the current detection unit 37, the inrush prevention circuit voltage detection unit 38, and the DC link voltage detection unit 44 to the notification unit 49, or, as shown in FIG. 9, the main power supply control unit 43 may be interposed in the transmission path of the signal. Of course, the notification unit 49 may issue a notification such as "A short circuit has occurred", "An open circuit has occurred", or "A disconnection has occurred" by voice. Also, a visual notification may be issued by a method other than lighting the light source, such as displaying a predetermined error code. Note that the first modification may further include a notification unit 49 similar to that of the second modification.

[0101] The following describes items that may be added or changed in the embodiments, etc.

[0102] In the embodiment, an auxiliary threshold Vth2 and an auxiliary threshold Vth3 may be set. The auxiliary threshold Vth3 is a voltage threshold lower than the main threshold Vth1 and the auxiliary threshold Vth2. The auxiliary threshold Vth2 is a voltage threshold lower than the main threshold Vth1. That is, the relationship of main threshold Vth1>second threshold Vth2>auxiliary threshold Vth3 is established.

[0103] The auxiliary threshold Vth2 is a threshold for determining whether the power supply switch 21 has switched from an on state to an off state. The auxiliary threshold Vth2 is set to, for example, about 90% of the main threshold Vth1.

[0104] The auxiliary threshold Vth2 may have any value as long as it satisfies the relationship: main threshold Vth1>auxiliary threshold Vth2>auxiliary threshold Vth3, but if the auxiliary threshold Vth2 is low, when the power supply switch 21 of the main power supply unit 30 is turned off and then turned on again before the DC link voltage falls below the auxiliary threshold Vth2, the power supply switch 21 may be turned on again before the short-circuit switch 31b is switched off, causing an inrush current to flow to the main power supply unit 30. Therefore, the auxiliary threshold Vth2 needs to be set taking this into consideration.

[0105] The auxiliary threshold Vth3 is a threshold for determining whether a sufficient DC link voltage is secured to drive the electric motor 102. The auxiliary threshold Vth3 is set according to the specifications of the actuator 10, and is set to, for example, about 50 VDC or more and 100 VDC or less.

[0106] The auxiliary threshold Vth2 is a threshold for determining whether the DC link voltage has changed from a value exceeding the auxiliary threshold Vth2 to a value equal to or lower than the auxiliary threshold Vth2, and the opposite is ignored. The auxiliary threshold Vth3 is a threshold for determining whether the DC link voltage has changed from a value exceeding the auxiliary threshold Vth3 to a value equal to or lower than the auxiliary threshold Vth3, and the opposite is ignored.

[0107] When the DC link voltage becomes equal to or lower than the auxiliary threshold Vth2 in the servo-on state, it may be determined that the power supply switch 21 of the main power supply unit 30 has been switched to the OFF state, and the short-circuit switch 31b of the inrush prevention circuit 31 may be switched to the OFF state, thereby putting the inrush prevention circuit 31 into the active state. Thereafter, when the DC link voltage is lower than the auxiliary threshold Vth2 and the servo is in the OFF state, the inrush prevention control unit 42 may maintain the short-circuit switch 31b in the OFF state.

[0108] Even in the servo-on state, the DC link voltage may drop below the auxiliary threshold Vth2 despite the power supply switch 21 of the main power supply unit 30 not being turned off to output current while the motor is being driven. Therefore, even if the DC link voltage falls below the auxiliary threshold Vth2, the short-circuit switch 31b may be maintained in the on state in the servo-on state.

[0109] Furthermore, when the DC link voltage falls below the auxiliary threshold Vth3 from a value equal to or greater than the auxiliary threshold Vth3 and is in the servo-on state, the inrush prevention control unit 42 may switch the short-circuit switch 31b of the inrush prevention circuit 31 to the off state. In this case, the inrush prevention control unit 42 may switch to the servo-off state regardless of whether a servo-off command has been received or not.

[0110] 1 Drive unit 10 Actuator 20 External power supply 21 Power supply switch 30 Main power section 31 Inrush protection circuit 31a Inrush protection resistor 31b Shorting switch 32 Converter 33 Inverter 36 Capacitor 37 Current detection section 38 Inrush prevention circuit voltage detection section 40 Upper device 41 Inverter control unit 42 Inrush prevention control unit 43 Main power supply control section 44 DC link voltage detector 90 Motor 100 Drive unit

Claims

1. A drive device that generates drive power for an electric motor based on power supplied from an external power source, A power generating unit that generates the driving power; an inrush prevention circuit including: an electrical resistor provided in a current transmission path between the external power supply and the power generating unit; and a first switch provided in parallel with the electrical resistor in the transmission path and switchable between conductive and non-conductive states, the inrush prevention circuit suppressing an inrush current from the external power supply; a second switch interposed between the external power supply and the inrush current prevention circuit and configured to be capable of switching on / off the supply of power; A first control unit that controls an operation of the first switch; A second control unit that controls an operation of the second switch; at least one of a current detection unit that detects a current between the inrush prevention circuit and the power generation unit, and a first voltage detection unit that detects a voltage between two points of the transmission line sandwiching the inrush prevention circuit; the second control unit makes the second switch non-conductive in response to an abnormality in the inrush current prevention circuit determined based on at least one of the current detected by the current detection unit and the voltage detected by the first voltage detection unit. Drive unit.

2. The current detection unit is provided, the first switch is controlled to be in a non-conducting state before the supply power is switched from an off state to an on state; the current detection unit compares a current after the supply power is switched from an OFF state to an ON state with a first threshold value to determine whether an abnormal short circuit has occurred in the first switch; The second control unit makes the second switch non-conductive when it is determined that an abnormal short circuit has occurred in the first switch. The drive device according to claim 1 .

3. the current detection unit compares a current after the supply power is switched from an OFF state to an ON state with a second threshold value to determine whether a disconnection has occurred between the transmission path and the electrical resistance; The second control unit makes the second switch non-conductive when it is determined that the disconnection has occurred. The drive device according to claim 2.

4. a third control unit that controls an operation of the power generating unit in response to an external input of a signal including a command related to the operation of the electric motor; The first voltage detection unit is provided. The first switch is controlled to be in a conductive state during operation control of the power generating unit by the third control unit, the first voltage detection unit compares a voltage detected during operation control of the power generation unit by the third control unit with a third threshold value to determine whether an abnormality has occurred that causes the first switch to be out of a conductive state; The second control unit makes the second switch non-conductive when it is determined that an abnormality has occurred in which the first switch is not in a conductive state. A drive device according to any one of claims 1 to 3.

5. The power generation unit is a converter that generates a direct current based on power supplied from the external power supply, which is an alternating current power supply; an inverter that converts the DC current into AC current and supplies the AC current to the electric motor; a capacitor connected to a positive transmission path and a negative transmission path of a current between the converter and the inverter to smooth the DC current; a second voltage detection unit that detects a voltage between the positive transmission line and the negative transmission line; The second voltage detection unit compares a voltage between the positive transmission path and the negative transmission path with a fourth threshold value to determine whether a break has occurred between the transmission path and the electrical resistor; The second control unit makes the second switch non-conductive when it is determined that the disconnection has occurred. The drive device according to claim 4.

6. A drive device according to any one of claims 1 to 3; A motor comprising the electric motor.

7. A motor according to claim 6; a mechanism connected to an output shaft of the electric motor and operating in response to a rotational driving force of the electric motor; An actuator comprising:

8. 1. A method for detecting an abnormality in an inrush current prevention circuit that suppresses an inrush current from an external power source in a drive device that generates drive power for an electric motor based on power supplied from the external power source, comprising: the inrush current prevention circuit includes an electrical resistor provided in a current transmission path between the external power supply and a power generating unit that generates the drive power, and a first switch provided in parallel with the electrical resistor in the transmission path and switchable between conductive and non-conductive states; a current detection unit that detects a current between the inrush prevention circuit and the power generation unit, and a first voltage detection unit that detects a voltage between two points of the transmission line sandwiching the inrush prevention circuit, and based on a detection result of at least one of these, the abnormality of the inrush prevention circuit is determined. Abnormality determination method.

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