Linear motor drive device and conveyance system
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-02-07
- Publication Date
- 2026-08-13
Smart Images
Figure JP2025004188_13082026_PF_FP_ABST
Abstract
Description
Linear Motor Driving Device and Conveying System
[0001] The present disclosure relates to a linear motor driving device and a conveying system.
[0002] In a production line where factory automation is introduced, for example, a production line for assembling industrial products or a production line for packaging food, a conveying system for conveying workpieces is generally used. In recent years, a conveying system that divides a conveying path for workpieces into a plurality of zones and runs a carriage on which workpieces are placed by a control device arranged in each zone has been widely used. Such a conveying system is known as one of the conveying systems excellent in terms of production efficiency.
[0003] As one form of the conveying system, a so-called moving magnet type linear motor is utilized, in which magnets constituting a mover are arranged on a carrier, and a plurality of coils are arranged on a stator constituting a conveying path.
[0004] Patent Document 1 discloses a braking method for a conveying system that moves a conveying device using a linear motor. The conveying system disclosed in Patent Document 1 individually controls the current flowing through each coil of the stator by an inverter circuit that is a full-bridge circuit or a half-bridge circuit. According to the technique of Patent Document 1, the conveying system brakes the conveying device by short-circuiting the coil by energizing a switching element constituting the inverter circuit.
[0005] Japanese Patent Application Laid-Open No. 2019-221131
[0006] However, according to the conventional technique disclosed in Patent Document 1, when an abnormality occurs in the switching element of the inverter circuit, it may be impossible to short-circuit the coil by energizing the switching element. Therefore, according to the conventional technique, it may be impossible to brake the carrier because the coil cannot be short-circuited.
[0007] The present disclosure has been made in view of the above, and an object thereof is to obtain a linear motor driving device that enables braking of a carrier by short-circuiting a coil.
[0008] To solve the above-mentioned problems and achieve the objective, the linear motor drive device according to this disclosure is a linear motor drive device that moves a transport body by supplying power to the transport body. The linear motor drive device according to this disclosure comprises a stator having a group of coils consisting of a plurality of coils connected in series with each other and generating power; an inverter unit having a plurality of series-connected switching elements and applying voltage to each of the plurality of coils; and a switch connected to one of the plurality of coils and another of the plurality of coils.
[0009] The linear motor drive device described herein has the effect of enabling braking of the transported object by short-circuiting the coils.
[0010] Figure showing an example configuration of the transport system according to Embodiment 1. Figure showing an example configuration of the transport path unit of the transport system according to Embodiment 1. Figure showing a first modified example of the transport path unit of the transport system according to Embodiment 1. Figure showing a second modified example of the transport path unit of the transport system according to Embodiment 1. Figure flowchart showing an example of the operation procedure of the transport path unit of the transport system according to Embodiment 1. Figure showing an example configuration of the control circuit according to Embodiment 1. Figure showing an example configuration of the dedicated hardware circuit according to Embodiment 1.
[0011] The linear motor drive device and transport system according to the embodiment will be described in detail below with reference to the drawings.
[0012] Embodiment 1. Figure 1 is a diagram showing an example of the configuration of the transport system 1 according to Embodiment 1. The transport system 1 is a system used for transporting objects. In Embodiment 1, the transport system 1 transports objects by moving a transport body on which the objects are placed.
[0013] The transport system 1 comprises a plurality of transport path units 11A, 11B, 11C, 11D, 11E, 11F, 11G, and 11H, a controller 12, a DC (Direct Current) power supply 13, and trolleys 16A, 16B, and 16C.
[0014] Each transport path unit 11A, 11B, 11C, 11D, 11E, 11F, 11G, and 11H functions as a linear motor drive device that moves a transported object by supplying power to it. The transport path units 11A, 11B, 11C, 11D, 11E, 11F, 11G, and 11H are connected to each other and constitute a transport path 10 on which the transported object moves.
[0015] The controller 12 operates the trolleys 16A, 16B, and 16C by controlling each transport path unit 11A, 11B, 11C, 11D, 11E, 11F, 11G, and 11H. Each of the trolleys 16A, 16B, and 16C is a transport body. In the following description, "transport path unit 11" refers to each of the transport path units 11A, 11B, 11C, 11D, 11E, 11F, 11G, and 11H without distinction. "Trolley 16" refers to each of the trolleys 16A, 16B, and 16C without distinction.
[0016] The transport path 10 shown in Figure 1 is a closed track-shaped path. The transport path 10 of the transport system 1 may also be an open path. That is, the transport path 10 of the transport system 1 may be a path with a start point and an end point that are far apart from each other.
[0017] The transport path units 11A, 11B, 11E, and 11F are straight transport path units 11 that constitute a straight path. The transport path units 11C, 11D, 11G, and 11H are curved transport path units 11 that constitute a curved path, and change the direction of travel of the transported body by 90 degrees. The transport path 10 may consist only of transport path units 11 that constitute a curved path, without having any transport path units 11 that constitute a straight path. A transport path 10 having a start point and an end point that are far apart from each other may consist only of transport path units 11 that constitute a straight path. The overall shape of the transport path 10 is arbitrary.
[0018] The trolley 16 is attached to the side of the transport path 10. The trolley 16 is equipped with guide rollers. The trolley 16 moves along a guide rail provided on the side of the transport path 10 by the rotation of the guide rollers. The trolley 16 moves along the side of the transport path 10 and stops on the side of the transport path 10. The transport system 1 according to Embodiment 1 is equipped with a moving magnet type linear motor. The trolley 16 may also move along a guide rail provided on the upper surface of the transport path 10. Alternatively, the trolley 16 only needs to be attached to the transport path 10 so that it can move along the transport path 10. The trolley 16 is equipped with a permanent magnet that constitutes a movable element, a permanent magnet for a linear scale, and guide rollers that move along the guide rail by rotation. In Figure 1, the guide rail, guide rollers, permanent magnet that constitutes a movable element, permanent magnet for a linear scale, and linear scale are not shown.
[0019] The direction of travel for each trolley 16 is either clockwise in Figure 1 or counterclockwise in Figure 1. Of the directions of travel, the clockwise direction in Figure 1 is defined as the forward direction. Of the directions of travel, the counterclockwise direction in Figure 1 is defined as the reverse direction. Arrow 17A represents the forward direction. Arrow 17B represents the reverse direction.
[0020] In the example shown in Figure 1, the transport system 1 comprises eight transport path units 11 and three trolleys 16. The number of transport path units 11 provided in the transport system 1 is arbitrary. That is, the number of transport path units 11 that constitute the transport path 10 is arbitrary. The transport system 1 may have multiple transport path units 11. The number of trolleys 16 that move along the transport path 10 is arbitrary. The transport system 1 may have one or more trolleys 16.
[0021] The DC power supply 13 is connected to each transport path unit 11 via a DC power bus 15. The DC power supply 13 is a power supply device or power supply circuit that outputs a DC voltage. The DC power supply 13 supplies power to each transport path unit 11. Each transport path unit 11 shares the DC power supply 13.
[0022] In the transport system 1, each transport path unit 11 is connected to the DC power supply 13 via a multidrop connection. The connection configuration between each transport path unit 11 and the DC power supply 13 is not limited to a multidrop connection; a daisy-chain connection is also possible. In the example shown in Figure 1, the transport system 1 is equipped with one DC power supply 13, but the transport system 1 may be equipped with multiple DC power supplies 13. In other words, the transport system 1 may be configured with multiple power supply domains.
[0023] The controller 12 controls each of the multiple transport path units 11. The controller 12 is connected to each transport path unit 11 via a data communication line 14. The data communication line 14 consists of a line connecting one of the multiple transport path units 11, which is transport path unit 11A, to the controller 12, and lines connecting adjacent transport path units 11 to each other. The transport system 1 has a configuration in which each transport path unit 11 is connected to the controller 12 by daisy-chain connection.
[0024] The connection configuration between each transport path unit 11 and the controller 12 is not limited to a daisy-chain connection. The connection configuration between each transport path unit 11 and the controller 12 may also be a star connection, where each transport path unit 11 is connected to the controller 12 via a communication hub. Alternatively, the transport system 1 may be equipped with multiple data communication lines 14, and each transport path unit 11 and the controller 12 may be directly connected via the data communication lines 14.
[0025] The controller 12 generates a position command indicating the position to which the trolley 16 should be moved. Based on the position command, the controller 12 generates a coil drive command. The controller 12 outputs the coil drive command to each transport path unit 11. By outputting the coil drive command to each transport path unit 11, the controller 12 controls the movement of each trolley 16.
[0026] Alternatively, the controller 12 may output a position command to each transport path unit 11. Each transport path unit 11 generates a coil drive command according to the position command. Each transport path unit 11 controls the movement of each trolley 16 based on the coil drive command.
[0027] Controller 12 may be connected to a higher-level control device, such as a programmable logic controller. Such a control device outputs commands for sequence control to Controller 12. A human-machine interface may also be connected to Controller 12. The human-machine interface accepts input from an operator. The human-machine interface also outputs information indicating the status of the transport system 1, such as by displaying it. Controller 12 may acquire operation information for each cart 16 from a higher-level control device or human-machine interface and generate position commands for each cart 16 based on the operation information. The operation information is information indicating the schedule for the movement of each cart 16 along the transport path 10.
[0028] Next, the configuration of the transport path unit 11 will be described. Here, a straight transport path unit 11 will be used as an example. In the curved transport path unit 11, the arrangement of the coils is different from that of the straight transport path unit 11. The configuration of the curved transport path unit 11 is the same as that of the straight transport path unit 11, except that the arrangement of the coils is different.
[0029] Figure 2 is a diagram showing an example of the configuration of a transport path unit 11 in the transport system 1 according to Embodiment 1. In Figure 2, the transport path unit 11 and a trolley 16 that moves along the transport path unit 11 are schematically shown. The trolley 16 has a permanent magnet 41 which is a movable element. The transport path unit 11 comprises a stator 21, an inverter unit 22, a switch 23, and a control unit 24.
[0030] The stator 21 has a plurality of coils 31. When current flows through each coil 31, it interacts with the magnetic field generated by the permanent magnet 41 to generate thrust that moves the trolley 16. In this way, each coil 31 generates thrust that moves the trolley 16 when current flows through it. In a linear transport path unit 11, the plurality of coils 31 are arranged in a linear direction. The trolley 16 moves in the linear direction in which the plurality of coils 31 are arranged.
[0031] In the example shown in Figure 2, the stator 21 has nine coils 31A, 31B, 31C, 31D, 31E, 31F, 31G, 31H, and 31I. Hereafter, the nine coils 31A, 31B, 31C, 31D, 31E, 31F, 31G, 31H, and 31I will be collectively referred to as the coil group. Furthermore, "coil 31" will refer to each of the coils 31A, 31B, 31C, 31D, 31E, 31F, 31G, 31H, and 31I without distinction.
[0032] The nine coils 31 of the stator 21 are connected in series with each other. Although the stator 21 is assumed to have nine coils 31 in the above description, the number of coils 31 in the transport path unit 11 is arbitrary.
[0033] The inverter unit 22 applies voltage to each of the multiple coils 31. The inverter unit 22 has multiple series units 32. Each series unit 32 is a series of multiple switching elements. In the example shown in Figure 2, each series unit 32 has two switching elements 33 and 34 connected in series with each other. Each series unit 32 can also be said to constitute a half-bridge circuit. Each switching element 33 and 34 is, for example, an FET (Field Effect Transistor). Each switching element 33 and 34 may also be an IGBT (Insulated Gate Bipolar Transistor), etc. The connection point 35 is the point where switching element 33 and switching element 34 are connected to each other. Each series unit 32 is connected in parallel to the DC power supply 13.
[0034] In the example shown in Figure 2, the inverter unit 22 has 10 series units 32A, 32B, 32C, 32D, 32E, 32F, 32G, 32H, 32I, and 32J. The series unit 32 refers to each of the series units 32A, 32B, 32C, 32D, 32E, 32F, 32G, 32H, 32I, and 32J without distinction.
[0035] One end of coil 31A is connected to the connection point 35 of series unit 32A. The other end of coil 31A is connected to the connection point 35 of series unit 32B. One end of coil 31B is connected to the connection point 35 of series unit 32B. The other end of coil 31B is connected to the connection point 35 of series unit 32C. One end of coil 31C is connected to the connection point 35 of series unit 32C. The other end of coil 31C is connected to the connection point 35 of series unit 32D. One end of coil 31D is connected to the connection point 35 of series unit 32D. The other end of coil 31D is connected to the connection point 35 of series unit 32E. One end of coil 31E is connected to the connection point 35 of series unit 32E. The other end of coil 31E is connected to the connection point 35 of series unit 32F.
[0036] One end of coil 31F is connected to the connection point 35 of series unit 32F. The other end of coil 31F is connected to the connection point 35 of series unit 32G. One end of coil 31G is connected to the connection point 35 of series unit 32G. The other end of coil 31G is connected to the connection point 35 of series unit 32H. One end of coil 31H is connected to the connection point 35 of series unit 32H. The other end of coil 31H is connected to the connection point 35 of series unit 32I. One end of coil 31I is connected to the connection point 35 of series unit 32I. The other end of coil 31I is connected to the connection point 35 of series unit 32J.
[0037] In the example shown in Figure 2, one end of the switch 23 is connected to the connection point 35 of the series unit 32A. The other end of the switch 23 is connected to the connection point 35 of the series unit 32J. As a result, the switch 23 is connected to coil 31A, which is one of the multiple coils 31, and to coil 31I, which is another of the multiple coils 31. Coil 31A is the coil 31 located at one end of the coil group. Coil 31I is the coil 31 located at the other end of the coil group. Here, the end of the coil group is defined as the end in the direction in which the multiple coils 31 are arranged. Coil 31A, the switch 23, and coil 31I are connected in series with each other.
[0038] Switch 23 is equipped with a normally closed contact (b-contact). Switch 23 is, for example, a contact-type mechanical relay. Switch 23 may also be a contactless MOSFET (Metal Oxide Semiconductor Field Effect Transistor) relay or a solid-state relay.
[0039] The control unit 24 is, for example, a microcontroller. The control unit 24 controls each switching element 33, 34 of each series unit 32. The control unit 24 controls the switching elements 33, 34 by sending control signals generated based on coil drive commands to the switching elements 33, 34. The control unit 24 also controls the switch 23. The control unit 24 controls the switch 23 by sending control signals to the switch 23.
[0040] In the example shown in Figure 2, the multiple coils 31 of the stator 21 are connected in series with each other. In addition, connection points 35 of the series assembly 32 are connected to both ends of the coil group and to the connection points between the coils 31.
[0041] The coil 31A and the two series units 32A and 32B form a full-bridge circuit. The inverter unit 22 can apply the voltage Vdc of the DC power supply 13 in both the forward and reverse directions to the coil 31A by switching the switching elements 33 and 34 of each series unit 32A and 32B. By rapidly switching the switching elements 33 and 34, an averaged intermediate voltage can be applied to the coil 31A. An AC voltage with an amplitude in the range of -Vdc to +Vdc can be applied to the coil 31A.
[0042] The above description of the coil 31A also applies to the coils 31 other than the coil 31A in the stator 21. That is, for each coil 31, the voltage Vdc of the DC power supply 13 in each of the forward and reverse directions is applied by switching the switching elements 33 and 34 of each series body 32 constituting the full-bridge circuit. Depending on the movement of the carriage 16, a voltage on only the positive side of the alternating current may be applied to a certain coil 31, or a voltage on only the negative side of the alternating current may be applied.
[0043] For example, one series body 32B is a component of the full-bridge circuit including the coil 31A and is also a component of the full-bridge circuit including the coil 31B. The series body 32B performs an operation for applying a voltage to each of the two coils 31A and 31B connected to the connection point 35 of the series body 32B. Each of the series bodies 32C, 32D, 32E, 32F, 32G, 32H, and 32I also performs an operation for applying a voltage to each of the two coils 31, similar to the series body 32B. Thus, each of the series bodies 32B, 32C, 32D, 32E, 32F, 32G, 32H, and 32I is used for applying a voltage to each of the two coils 31.
[0044] In the example shown in FIG. 2, by setting the number of series bodies 32 included in the inverter unit 22 to be one more than the number of coils 31, it is possible to apply a voltage to each of the plurality of coils 31 of the stator 21.
[0045] Here, let the number of coils 3`1 included in the stator 21 be N. N is an integer of 2 or more. Since one series body 32 has two switching elements 33 and 34, in the example shown in FIG. 2, the number of switching elements 33 and 34 included in the inverter unit 22 is {(N + `1) × 2} pieces. On the other hand, if it is assumed that two series bodies 32 are provided independently for all the coils 31, the number of switching elements 33 and 34 included in the inverter unit 22 is (N × 4) pieces. In the first embodiment, by adopting a configuration in which each of the series bodies 32B, 32C, 32D, 32E, 32F, 32G, 32H, and 32I is used for applying a voltage to each of the two coils 31, the number of switching elements 33 and 34 in the inverter unit 22 can be reduced.
[0046] In a linear motor, in order for the effect of having a plurality of coils 31 that can be individually controlled to be reflected in the movement of an actual carrier, generally, the number of coils 31 needs to be four or more. In order to enable the movement of the carriage 16 by the conveyance path unit 11, the number of coils 31 of the stator 21 shall be four or more. Also, the number of series bodies 32 of the inverter unit 22 shall be five or more.
[0047] In the above, the inverter unit 22 is assumed to have (N + 1) series bodies 32 that constitute a half-bridge circuit. At least one of the series bodies 32 of the inverter unit 22 may be replaced with a configuration different from that of the series body 32. The inverter unit 22 may be provided with a voltage regulator such as a multi-level half-bridge inverter.
[0048] During normal operation of moving the carriage 16, the conveyance path unit 11 keeps the switch 23 open. When the switch 23 is closed according to the control by the control unit 24, a plurality of coils 31 of the stator 21 enter a short-circuit state. The conveyance path unit 11 brakes the carriage 16 by closing the switch 23 to short-circuit a plurality of coils 31. The conveyance path unit 11 can brake the carriage 16 at any location where the coils 31 are arranged by short-circuiting all of the plurality of coils 31.
[0049] The conveyance path unit 11 has a drive power source for operating the switch 23. In FIG. 2, the illustration of the drive power source is omitted. When the power supply from the drive power source to the switch 23 is cut off, the switch 23 closes. Thereby, when an abnormality occurs in which the power supply to the switch 23 is lost, the conveyance path unit 11 brakes the carriage 16 by closing the switch 23 to short-circuit a plurality of coils 31.
[0050] In the above, the conveyance path unit 11 is assumed to have one switch 23. The conveyance path unit 11 may be provided with a plurality of switches 23.
[0051] Figure 3 shows a first modified example of the transport path unit 11 of the transport system 1 according to Embodiment 1. The transport path unit 11 according to the first modified example includes two switches 23A and 23B.
[0052] In the example shown in Figure 3, one end of switch 23A is connected to the connection point 35 of series unit 32A. The other end of switch 23A is connected to the connection point 35 of series unit 32D. One end of switch 23B is connected to the connection point 35 of series unit 32D. The other end of switch 23B is connected to the connection point 35 of series unit 32H. The control unit 24 controls the switching elements 33 and 34 of each series unit 32. The control unit 24 also controls switches 23A and 23B.
[0053] During normal operation to move the trolley 16, the transport path unit 11 keeps switches 23A and 23B open. When switch 23A is closed according to control by the control unit 24, coils 31A, 31B, and 31C are short-circuited. When switch 23B is closed according to control by the control unit 24, coils 31D, 31E, 31F, and 31G are short-circuited. The transport path unit 11 brakes the trolley 16 by closing at least one of switches 23A and 23B, thereby short-circuiting several coils 31.
[0054] Each switch 23A and 23B is supplied with power from the drive power supply. In Figure 2, the drive power supply is not shown. If the power supply to switches 23A and 23B from the drive power supply is cut off, each switch 23A and 23B will be closed. As a result, if an abnormality occurs in which the power supply to switches 23A and 23B is lost, the transport path unit 11 will brake the trolley 16 by closing switches 23A and 23B and short-circuiting coils 31A, 31B, 31C, 31D, 31E, 31F, and 31G.
[0055] In the example shown in Figure 3, there is no switch 23 for short-circuiting coils 31H and 31I. Thus, in Embodiment 1, among the multiple coils 31 of the stator 21, there may be coils 31 that are not subject to short-circuiting by the switch 23. In the example shown in Figure 3, the number of switches 23 in the transport path unit 11 is set to two, but the number of switches 23 in the transport path unit 11 may be three or more. Furthermore, the position to which each switch 23 is connected is not limited to the same position as in Figure 3, but is arbitrary. The transport path unit 11 according to Embodiment 1 only needs to have a switch 23 connected to at least one of the multiple coils 31 and another of the multiple coils 31. The number of switches 23 provided in the transport path unit 11 may be one or multiple.
[0056] The transport path unit 11 may be equipped with a braking resistor, as will be described below. Figure 4 shows a second modified example of the transport path unit 11 in the transport system 1 according to Embodiment 1. The transport path unit 11 according to the second modified example is equipped with a braking resistor 25 connected in series with the switch 23. By being equipped with the braking resistor 25, the transport path unit 11 can improve the braking force compared to the case in which the braking resistor 25 is not equipped. The transport path unit 11 according to the second modified example is not limited to being equipped with one switch 23, but may be equipped with multiple switches 23.
[0057] Next, the operation of the transport path unit 11 during braking will be described. Here, the transport path unit 11 is assumed to have the configuration shown in Figure 2. The transport path unit 11 forms a closed circuit including the multiple coils 31 by closing the switch 23 and short-circuiting the multiple coils 31. When the trolley 16 is moving, the multiple coils 31 form a closed circuit, generating an electromotive force in each coil 31. The generation of an electromotive force in each coil 31 causes a braking current to flow through each coil 31. As the braking current flows through the closed circuit including the coil resistance of each coil 31 and returns to each coil 31, the transport path unit 11 generates a braking force in the opposite direction to the direction in which the trolley 16 is moving. At this time, all switching elements 33 and 34 of the inverter unit 22 are in an open state.
[0058] Because switch 23 is equipped with a normally closed (b) contact, as described above, when the power supply to switch 23 from the drive power source is interrupted, switch 23 remains closed. As a result, if an abnormality occurs in which the power supply to switch 23 is lost, the transport path unit 11 brakes the trolley 16 by closing switch 23 and short-circuiting the multiple coils 31.
[0059] In the above configuration, the transport path unit 11 brakes the trolley 16 by closing the switch 23. Alternatively, the transport path unit 11 may brake the trolley 16 by energizing the switching elements 33 and 34 in at least two of the multiple series units 32.
[0060] For example, the transport path unit 11 short-circuits multiple coils 31 of the stator 21 by energizing the switching elements 33 and 34 of the series unit 32A and the switching elements 33 and 34 of the series unit 32J. In this case as well, the transport path unit 11 can brake the trolley 16. In this example, the transport path unit 11 short-circuits multiple coils 31 by energizing the switching elements 33 and 34 in each of the series units 32 of the inverter unit 22: the series unit 32A connected to the coil 31A located at one end of the coil group, and the series unit 32J connected to the coil 31I located at the other end of the coil group. In this case, the transport path unit 11 can short-circuit all the coils 31 of the stator 21 by using the switching elements 33 and 34 of the coils 31A and 31I.
[0061] However, if an abnormality occurs in the switching elements 33 and 34 of the inverter unit 22, it may become impossible to short-circuit the coil 31 by energizing the switching elements 33 and 34. For this reason, the transport path unit 11 may short-circuit the coil 31 by closing the switch 23 if an abnormality occurs in the switching elements 33 and 34.
[0062] A first example of a malfunction in the switching elements 33 and 34 is an overcurrent in the switching elements 33 and 34. When the transport path unit 11 detects a malfunction caused by an overcurrent in at least one of the multiple series units 32 of the inverter unit 22, it closes the switch 23 to short-circuit the multiple coils 31.
[0063] A second example of a malfunction in the switching elements 33 and 34 is overheating of the switching elements 33 and 34. The transport path unit 11 short-circuits the multiple coils 31 by closing the switch 23 when there is a malfunction due to overheating in at least one of the multiple series units 32 of the inverter unit 22.
[0064] The transport path unit 11 may short-circuit the multiple coils 31 using the switch 23 when braking when there is a malfunction in the switching elements 33 and 34, and short-circuit the multiple coils 31 using the switching elements 33 and 34 when braking when there is no malfunction in the switching elements 33 and 34. By using the switch 23 when there is a malfunction in the switching elements 33 and 34, the transport path unit 11 can prevent a situation where the coils 31 cannot be short-circuited and the trolley 16 cannot be braked. By using the switching elements 33 and 34 when there is no malfunction in the switching elements 33 and 34, the transport path unit 11 can slow down the deterioration of the switch 23. For example, if the switch 23 is a coil relay with mechanical contacts, the lifespan of the switch 23 can be extended by minimizing the opening and closing operations of the switch 23.
[0065] Figure 5 is a flowchart illustrating an example of the operation procedure of a transport path unit 11 in the transport system 1 according to Embodiment 1. In this example, if the transport path unit 11 determines that at least one of the series elements 32 in the inverter unit 22 is abnormal, it closes the switch 23 to short-circuit two or more of the coils 31. Also, if the transport path unit 11 determines that the series elements 32 in the inverter unit 22 are normal, it short-circuits two or more of the coils 31 by energizing the switching elements 33 and 34 in each of the two or more series elements 32 in the inverter unit 22.
[0066] In step S1, the control unit 24 of the transport path unit 11 determines whether or not an abnormality has been detected in the switching elements 33 and 34 in at least one of the series members 32 of the inverter unit 22.
[0067] If an abnormality is detected in the switching elements 33 and 34 (step S1, Yes), the control unit 24 sends a control signal to the switch 23 to cause it to close. The switch 23 closes according to the control signal. As a result, in step S2, the transport path unit 11 short-circuits the multiple coils 31 by closing the switch 23.
[0068] On the other hand, if no abnormality is detected in the switching elements 33 and 34 (step S1, No), the control unit 24 sends a control signal to the switching elements 33 and 34 of the series unit 32 that has been set in advance to energize the switching elements 33 and 34. The switching elements 33 and 34 of the series unit 32 energize according to the control signal. As a result, in step S3, the transport path unit 11 short-circuits the multiple coils 31 by energizing the switching elements 33 and 34.
[0069] The transport path unit 11 terminates its operation according to the procedure shown in Figure 5 upon completion of step S2 or step S3.
[0070] In the above, the control unit 24 determines whether or not to apply braking in the transport path unit 11 and then applies braking to the trolley 16. The transport system 1 may also determine whether or not to apply braking to the trolley 16 using the controller 12 and then have each transport path unit 11 apply braking. As one example, if the transport system 1 determines that there is an abnormality in at least one of the multiple transport path units 11, it may have both the abnormal transport path unit 11 and the other transport path units 11 apply braking. In this way, the transport system 1 can apply braking to the trolley 16 in all transport path units 11 if an abnormality occurs in at least one of the multiple transport path units 11.
[0071] Next, the hardware that implements the control unit 24 of the transport path unit 11 will be described. The control unit 24 is implemented by a processing circuit. The processing circuit may be a circuit in which a processor executes software, or it may be a dedicated circuit.
[0072] When the processing circuit is implemented by software, the processing circuit is, for example, the control circuit shown in Figure 6. Figure 6 is a diagram showing an example configuration of the control circuit 50 according to Embodiment 1. The control circuit 50 includes an input unit 51, a processor 52, a memory 53, and an output unit 54. The input unit 51 is an interface circuit that receives data input from outside the control circuit 50 and provides it to the processor 52. The output unit 54 is an interface circuit that sends data from the processor 52 or the memory 53 to the outside of the control circuit 50.
[0073] When the processing circuit is the control circuit 50 shown in Figure 6, the control unit 24 is implemented by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in memory 53. The processing circuit implements the functions of the control unit 24 by having the processor 52 read and execute the program stored in memory 53. In other words, the processing circuit includes memory 53 for storing the program that will ultimately be executed as a result of the processing of the control unit 24. These programs can also be said to cause the computer to execute the procedures and methods of processing of the control unit 24.
[0074] The processor 52 is a CPU (Central Processing Unit). The processor 52 may also be a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor). The memory 53 may be, for example, a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM® (Electrically Erasable Programmable Read Only Memory), magnetic disk, flexible disk, optical disk, compact disk, minidisc, or DVD (Digital Versatile Disc).
[0075] Figure 6 shows an example of hardware in which the control unit 24 is implemented using a general-purpose processor 52 and memory 53, but the control unit 24 may also be implemented using a dedicated hardware circuit. Figure 7 shows an example of the configuration of a dedicated hardware circuit 55 according to Embodiment 1.
[0076] The dedicated hardware circuit 55 includes an input section 51, an output section 54, and a processing circuit 56. The processing circuit 56 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a circuit combining these. The control unit 24 may be implemented by the processing circuit 56 for each function, or all functions may be implemented together by the processing circuit 56. The control unit 24 may also be implemented by combining the control circuit 50 and the hardware circuit 55.
[0077] According to Embodiment 1, the linear motor drive device comprises a stator 21 having a coil group consisting of a plurality of coils 31 connected in series to each other and generating power, an inverter unit 22 having a plurality of series units 32 of a plurality of switching elements 33, 34 and applying voltage to each of the plurality of coils 31, and a switch 23 connected to one of the plurality of coils 31 and another of the plurality of coils 31. The linear motor drive device has a plurality of coils 31 connected in series to each other and is equipped with a switch 23, so that even if a malfunction occurs in at least one of the switching elements 33, 34 of the plurality of series units 32, the coils 31 can be short-circuited. As a result, the linear motor drive device has the effect of enabling braking of the transported object by short-circuiting the coils 31.
[0078] The switch 23 may be connected to a coil 31 located at one end of the coil group and another coil 31 located at the other end of the coil group. This allows the linear motor drive to short-circuit all of the coils 31 of the stator 21.
[0079] The switch 23 may also have a normally closed (b) contact. This allows the linear motor drive unit to short-circuit multiple coils 31 and brake the trolley 16 in the event of an abnormality where the power supply to the switch 23 is lost.
[0080] The linear motor drive unit may also be equipped with a braking resistor 25 connected in series with the switch 23. This allows the linear motor drive unit to improve braking force compared to the case where the braking resistor 25 is not provided.
[0081] The stator 21 may have four or more coils 31. This allows the linear motor drive device to move the transported object using the coils 31 of the stator 21.
[0082] The number of series units 32 in the inverter unit 22 may be one more than the number of coils 31 in the stator 21. This allows the linear motor drive device to control the voltage applied to each of the coils 31 in the stator 21 using a smaller number of series units 32.
[0083] The linear motor drive unit may short-circuit two or more of the coils 31 by closing the switch 23 if it is determined that at least one of the series members 32 of the inverter unit 22 is abnormal, or short-circuit two or more of the coils 31 by energizing the switching elements 33, 34 in each of the two or more series members 32 of the inverter unit 22 if it is determined that the series members 32 of the inverter unit 22 are normal. This allows the linear motor drive unit to brake the transported object by short-circuiting the coils 31 in both cases: when at least one of the series members 32 is abnormal, and when none of the series members 32 are abnormal. In addition, the linear motor drive unit can slow down the deterioration of the switch 23.
[0084] The linear motor drive unit short-circuits multiple coils 31 by energizing the switching elements 33 and 34 in each of the series units 32 of the inverter unit 22: one series unit 32 connected to a coil 31 located at one end of the coil group, and another series unit 32 connected to a coil 31 located at the other end of the coil group. As a result, the linear motor drive unit can short-circuit all of the coils 31 of the stator 21.
[0085] An abnormality in at least one of the series components 32 of the inverter unit 22 may be an abnormality caused by an overcurrent in at least one of the series components 32. This allows the linear motor drive device to short-circuit two or more of the coils 31 when there is an abnormality caused by an overcurrent in at least one of the series components 32 of the inverter unit 22.
[0086] An abnormality in at least one of the series components 32 of the inverter unit 22 may be an abnormality caused by overheating in at least one of the series components 32. This allows the linear motor drive device to short-circuit two or more of the coils 31 when there is an abnormality caused by overheating in at least one of the series components 32 of the inverter unit 22.
[0087] The configurations shown in the embodiments described above are examples of the content of this disclosure. The configurations of the embodiments can be combined with other known technologies. Some parts of the configurations of the embodiments can be omitted or modified without departing from the spirit of this disclosure.
[0088] 1. Transport system, 10. Transport path, 11, 11A, 11B, 11C, 11D, 11E, 11F, 11G, 11H. Transport path unit, 12. Controller, 13. DC power supply, 14. Data communication line, 15. DC power bus, 16, 16A, 16B, 16C. Trolley, 17A, 17B. Arrow, 21. Stator, 22. Inverter section, 23, 23A, 23B. Switch, 24. Control unit, 25. Braking resistor, 31, 31A, 31B, 31C, 31D, 31E, 31F, 31G, 31H, 31I. Coil, 32, 32A, 32B, 32C, 32D, 32E, 32F, 32G, 32H, 32I, 32J. Series unit, 33, 34. Switching element, 35. Connection point, 41. Permanent magnet, 50 control circuit, 51 input section, 52 processor, 53 memory, 54 output section, 55 hardware circuit, 56 processing circuit.
Claims
1. A linear motor drive device for moving a transport body by supplying power to the transport body, comprising: a stator having a group of coils consisting of a plurality of coils connected in series with each other and generating the power; an inverter unit having a plurality of series-connected switching elements and applying voltage to each of the plurality of coils; and a switch connected to one of the plurality of coils and another of the plurality of coils.
2. The linear motor drive device according to claim 1, characterized in that the switch is connected to the coil located at one end of the coil group and the coil located at the other end of the coil group.
3. The linear motor drive device according to claim 1 or 2, characterized in that the switch is provided with a normally closed contact.
4. A linear motor drive device according to any one of claims 1 to 3, characterized in that it comprises a braking resistor connected in series with the switch.
5. The linear motor drive device according to any one of claims 1 to 4, characterized in that the number of coils in the stator is four or more.
6. The linear motor drive device according to any one of claims 1 to 5, characterized in that the number of series units in the inverter unit is one greater than the number of coils in the stator.
7. A linear motor drive device according to any one of claims 1 to 6, characterized in that, when at least one of the series members of the inverter unit is determined to be abnormal, two or more of the coils are short-circuited by closing the switch, and when the series members of the inverter unit are determined to be normal, two or more of the coils are short-circuited by energizing the switching elements in each of the two or more series members of the inverter unit.
8. The linear motor drive device according to claim 7, characterized in that a plurality of coils are short-circuited by energizing the switching elements in each of the series members of the inverter unit, specifically the series member connected to the coil located at one end of the coil group and the series member connected to the coil located at the other end of the coil group.
9. The linear motor drive device according to claim 7 or 8, characterized in that the abnormality is caused by an overcurrent occurring in at least one of the series members.
10. The linear motor drive device according to claim 7 or 8, characterized in that the abnormality is caused by overheating in at least one of the series members.
11. A transport system comprising a plurality of transport path units that constitute a transport path on which a transported object moves, wherein each of the plurality of transport path units comprises a stator having a group of coils consisting of a plurality of coils connected in series with each other that move the transported object by supplying power to the transported object and generate the power, an inverter unit having a plurality of series-connected switching elements that apply voltage to each of the plurality of coils, and a switch connected to one of the plurality of coils and another of the plurality of coils.