Motor System

Abstract

A motor driver (21) supplies power to a plurality of motors (10). Among the plurality of motors (10), a switch unit (31) selectively switches target motors to which the power output by the motor driver (21) is to be supplied. An output control unit (6) has a plurality of motor controllers (2) for controlling one motor (10) and controls the motor driver (21) so that the motor driver (21) outputs the power on the basis of the output of each of the motor controllers (2). A switching control unit (5) controls the switch unit (31) so that the target motors are switched in a cyclic manner among the motors (10), the number of which is less than or equal to that of the motor controllers (2), among the plurality of motors (10).

Description

[Technical field]

[0001] The present invention relates to a motor system in which a plurality of motors are driven by a motor driver. [Background technology]

[0002] Conventionally, motor systems have been known in which the power output by a motor driver is distributed to a plurality of motors in a time-division manner. Patent Document 1 discloses this type of motor system.

[0003] In the motor drive device disclosed in Patent Document 1, multiple motors are connected to only one motor driver via a switching circuit unit. The motor driver controls the on / off of six transistors to apply appropriate voltages to the U-, V-, and W-phase drive coils of each motor. Each transistor is driven by a drive method using a pulse signal based on a pulse width modulation method. Multiple motors are driven simultaneously by appropriately operating the switching circuit unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-288964 A Summary of the Invention [Problem to be solved by the invention]

[0005] When multiple motors are connected to only one motor driver as in Patent Document 1, the switching circuit repeats the operation of connecting the motor driver to all of the multiple motors in order to drive all the motors simultaneously. However, when there are a large number of motors, the power supplied to each motor becomes small, making it difficult to generate a strong torque in the motors.

[0006] In Patent Document 1, it was not possible to individually control the rotation speed and rotation direction of multiple motors that were driven simultaneously. The inventors of the present application have newly discovered that when a large number of motors are connected to a motor driver, the control configuration may become complicated.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to increase the power allocated to each motor in a motor system in which a single motor driver drives multiple motors, while realizing independent control with a simple configuration.

[0008] The problem to be solved by the present invention has been described above. Next, the means for solving this problem and the effects thereof will be described.

[0009] According to an aspect of the present invention, there is provided a motor system having the following configuration. That is, the motor system includes a plurality of motors, a motor driver, a switch unit, an output control unit, and a switching control unit. The motor driver supplies power to generate driving force to the plurality of motors. The switch unit selectively switches a target motor, which is a target of the supply of power output by the motor driver, between the plurality of motors. The output control unit has a plurality of motor controllers that control one of the motors, and controls the motor driver so that the motor driver outputs power based on the output of each of the motor controllers. The switching control unit controls the switch unit so that the target motor is cyclically switched between the motors among the plurality of motors, the number of which is equal to or less than the number of the motor controllers.

[0010] This allows multiple motors to be controlled independently in a motor system in which one motor driver drives multiple motors. By setting the number of motor controllers to be less than the number of motors connected to the motor driver, the number of motor controllers can be reduced and the configuration can be simplified. In addition, by limiting the number of motors that can be driven simultaneously, the power allocated from the motor driver to each motor can be increased.

[0011] The motor system is preferably configured as follows. That is, the motor system includes a plurality of moving bodies and a position detection unit. The position detection unit detects the position of the moving bodies. The plurality of motors move the plurality of moving bodies. The output control unit assigns the motor controller to the motor selected from the plurality of motors and releases the assignment based on the detection result of the position detection unit. The output control unit controls the motor driver so that the motor driver outputs power based on the output of the motor controller assigned to any one of the plurality of motors. The switching control unit controls the switch unit so that the target motor is cyclically switched between the motors assigned to the motor controllers and so that power equivalent to the output of the motor controller is output to the motor assigned to the motor controller.

[0012] With this, when a moving object moves across a plurality of motors, the motor controller can be switched to the motor to be assigned based on detection by the position detector, and the plurality of motors can be operated in cooperation with each other.

[0013] In the motor system, each of the plurality of motor controllers preferably includes a position control section that controls a position of the motor.

[0014] This allows the positions of multiple motors to be controlled independently.

[0015] In the motor system, each of the plurality of motor controllers preferably includes a speed control section that controls the speed of the motor.

[0016] This allows the speed of multiple motors to be controlled independently.

[0017] In the above motor system, it is preferable that the speed control unit is provided in a device separate from the motor driver.

[0018] In this way, since multiple speed control units are provided in a device different from the motor driver, the motor driver does not need to have a special structure, and it is therefore easy to apply a general-purpose motor driver for driving a single motor.

[0019] The motor system is preferably configured as follows: the motor driver includes a current control section that controls a current flowing through the motor. The current control section receives outputs from the speed control sections of the multiple motor controllers while switching them cyclically. In the current control section, control that depends on past information is disabled.

[0020] This makes it possible to prevent past information about a motor from affecting the control of other motors, thereby preventing unintended operation of the motors.

[0021] The motor system is preferably configured as follows: each of the motor controllers includes a current integrator that integrates the deviation between a current command output from the motor controller and a current flowing through the motor that is the target of control by the motor controller; the motor driver adds the proportional control output of the current controller and an input from the current integrator, and outputs power based on the result of this addition.

[0022] This makes it possible to realize integral control of the current of each motor, thereby reducing steady-state deviation. Since a current integrator is provided for each motor controller, it is possible to prevent past current deviations for a motor from affecting the control of other motors. [Brief description of the drawings]

[0023] [Figure 1]1 is a block diagram of a motor system according to an embodiment of the present invention. [Diagram 2] 11 is a chart showing how the output of multiple motor controllers and the state of selector switches change upon detection of a trolley by an encoder. [Diagram 3] FIG. 11 is a block diagram of a motor system according to a modified example. [Figure 4] FIG. 4 is a block diagram showing a configuration example in which each motor controller includes a current integrator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Next, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram of a motor system 100 of the present embodiment.

[0025] The motor system 100 is a system for controlling a plurality of motors 10. The motor system 100 of this embodiment is applied to, for example, a transport system that drives a plurality of carts (moving bodies) 7 to transport luggage.

[0026] As shown in FIG. 1, the motor system 100 includes a control unit 1, a motor driver 21, a switch unit 31, a plurality of motors 10, and a plurality of encoders (position detection units) 41.

[0027] The control unit 1 controls a plurality of motors 10 via a motor driver 21 and a switch unit 31 .

[0028] The control unit 1 includes a plurality of motor controllers 2. Fig. 1 shows an example in which the control unit 1 includes three motor controllers 2. The number of motor controllers 2 is arbitrary as long as it is plural.

[0029] The maximum number of motors 10 that one motor controller 2 can control simultaneously (at one point in time) is one. In other words, one motor controller 2 cannot control multiple motors 10 simultaneously. Since the control unit 1 has three motor controllers 2, the upper limit number of motors 10 that the control unit 1 can control simultaneously (at one point in time) is three. Since the number of motors 10 in this embodiment is five, the upper limit number of motors 10 that the control unit 1 can control is less than the number of motors 10.

[0030] The control unit 1 includes a first selection switch 3, an allocation unit 4, and a switching control unit 5.

[0031] The control unit 1 is configured as a computer including, for example, a CPU, a ROM, a RAM, an auxiliary storage device, etc. The auxiliary storage device is configured as, for example, a HDD, an SSD, etc. Various programs and the like are stored in the auxiliary storage device. Through such cooperation between hardware and software, the control unit 1 can function as a first selection switch 3, an allocation unit 4, a switching control unit 5, and a plurality of motor controllers 2.

[0032] The first selection switch 3 is configured as, for example, a software switch capable of high-speed switching. The first selection switch 3 is connected to the output sides of the multiple motor controllers 2.

[0033] The control unit 1 and the motor driver 21 are communicatively connected. The first selection switch 3 can send one output selected from the outputs of the multiple motor controllers 2 to the motor driver 21. The first selection switch 3 can switch which of the motor controllers 2 outputs is input to the motor driver 21.

[0034] The allocation unit 4 performs a process of allocating any one of the motor controllers 2 to each of the multiple motors 10, and a process of canceling the allocation. Since the allocation and canceling of the allocation are performed dynamically, which motor 10 the motor controller 2 is assigned to changes depending on the situation (for example, based on position detection information on the bogie 7 from the encoder 41). Once the motor controller 2 is assigned to a motor 10, it takes charge of controlling that motor 10 until the allocation is canceled.

[0035] In this embodiment, the allocation unit 4 and the multiple motor controllers 2 constitute an output control unit 6. The output control unit 6 controls a motor driver 21.

[0036] The switching control unit 5 controls the first selection switch 3 to switch repeatedly.

[0037] Let us consider a case in which all of the three motor controllers 2 are assigned to any of the motors 10. In this case, the switching control unit 5 controls the first selection switch 3 so that the outputs of the three motor controllers 2 are input to the motor driver 21 while being cyclically switched at predetermined time intervals.

[0038] When two of the three motor controllers 2 are assigned to the motor 10, the switching control unit 5 controls the first selection switch 3 so that the outputs of the two motor controllers 2 are cyclically switched at predetermined time intervals and input to the motor driver 21.

[0039] In this embodiment, the above-mentioned predetermined time is equally divided into three. The three divided times correspond to the three motor controllers 2, respectively.

[0040] In this embodiment, the time division number is fixed at 3. Therefore, for example, if one of the three motor controllers 2 is not assigned to the motor 10, 1 / 3 of the above-mentioned predetermined time is free time. However, the first selection switch 3 can also be controlled so that the input to the motor driver 21 is switched only between the outputs of the motor controllers 2 assigned to the motor 10. This control can be realized, for example, by dynamically changing the time division number and the above-mentioned predetermined time according to the number of motor controllers 2 assigned to the motor 10.

[0041] The switching control section 5 outputs a switching signal for repeatedly switching the second selection switch 35 of the switch section 31 in conjunction with the repeated switching of the first selection switch 3 of the control section 1. This will be described in detail later.

[0042] Next, the motor controller 2 will be described. Since the multiple motor controllers 2 have the same configuration, one motor controller 2 will be described below as a representative. The motor controller 2 includes a command generation unit 15, a position control unit 16, and a speed control unit 17.

[0043] Command generating unit 15 generates a command related to a target position of a mover of motor 10. The target position is determined, for example, based on a signal from a higher-level computer (not shown). Command generating unit 15 outputs the position command to position control unit 16.

[0044] Position control unit 16 controls the position of the mover of motor 10. Although details will be described later, the position of the mover provided in motor 10 is detected by encoder 41. Position control unit 16 compares, for example, the current position of the mover detected by encoder 41 with the position command input from command generation unit 15, and outputs a speed command to speed control unit 17 according to the position deviation.

[0045] The speed control unit 17 controls the speed of the mover of the motor 10. For example, the speed control unit 17 compares a current speed based on a change in the position of the mover detected by the encoder 41 with a speed command input from the position control unit 16, and generates a current command according to the deviation of the speed. In this embodiment, the current command is a signal that indicates a current value. In this embodiment, this current command corresponds to the output of the motor controller 2. This current command is input to a current control unit 25 provided in the motor driver 21, the details of which will be described later.

[0046] The motor driver 21 supplies power to the multiple motors 10 to operate the motors 10. The motor driver 21 is, for example, a servo amplifier or an inverter.

[0047] The motor driver 21 includes a current control unit 25, an inverter control unit 26, and an inverter 27.

[0048] The current control unit 25 controls the current flowing through the motor 10. The motor driver 21 includes a current sensor (not shown) to detect the current value, which is the magnitude of the current flowing through the motor 10. In this embodiment, the current sensor is of a known configuration that outputs a voltage according to the magnitude of the detected current. The current sensor may be provided in, for example, the switch unit 31 instead of the motor driver 21.

[0049] The current control unit 25 compares the detected current value with a current command input from the motor controller 2 of the control unit 1 (in other words, the speed control unit 17), and outputs a control signal according to the deviation of the current. In this embodiment, the control signal is a voltage signal indicating the duty ratio of the PWM control performed in the inverter 27.

[0050] The inverter control unit 26 controls the inverter 27 so that the inverter 27 generates a voltage corresponding to the control signal. The control signal input from the current control unit 25 to the inverter control unit 26 is a command value for a known PWM control performed in the inverter 27. PWM is an abbreviation for pulse width modulation. The inverter control unit 26 generates an on / off signal for a switch element provided in the inverter 27 so as to realize a duty ratio corresponding to this command value. This signal is output from the inverter control unit 26 to the inverter 27.

[0051] The inverter 27 is configured to include a known inverter circuit. The inverter circuit includes a plurality of switch elements (not shown). The switch elements are switched on / off in accordance with a signal input from the inverter control unit 26, whereby the inverter 27 converts a DC voltage into an AC voltage. In this embodiment, each motor 10 is a three-phase motor. Correspondingly, the inverter 27 generates a three-phase AC voltage from the DC voltage. This AC voltage corresponds to the output of the motor driver 21. The motor driver 21 outputs the AC voltage to the switch unit 31.

[0052] The switch unit 31 selectively supplies the power output by the motor driver 21 to the multiple motors 10. The switch unit 31 is configured as a circuit including a second selection switch .

[0053] The second selection switch 35 can supply the voltage waveform that is the output of the motor driver 21 to a selected motor 10 from among the multiple motors 10. In addition, the second selection switch 35 can switch to which motor 10 the output of the motor driver 21 is supplied. Hereinafter, the motor 10 to which the power is supplied from the motor driver 21 may be referred to as the target motor.

[0054] At any given moment, the target motor to which power is supplied is only one of the multiple motors 10 connected to the switch unit 31. The above-mentioned switching control unit 5 controls the switch unit 31 by a switching signal so that the switch unit 31 quickly repeats the operation of cyclically switching the target motor among the specific multiple motors 10. This makes it possible to drive the multiple motors 10 substantially simultaneously.

[0055] The second selection switch 35 is controlled by the switching control unit 5 so as to be switched simultaneously in conjunction with the first selection switch 3. More specifically, when the motor controller 2 is selected by the first selection switch 3, the switching control unit 5 controls the second selection switch 35 so that the motor 10 to which the motor controller 2 is assigned is selected as the target motor.

[0056] Consider a case where multiple motor controllers 2 are assigned to any one of the motors 10 by the assignment unit 4 included in the control unit 1. The current command output by the control unit 1 to the motor driver 21 is a time-division synthesis of the current commands of the multiple motor controllers 2 through cyclic switching operation of the first selection switch 3. Therefore, the voltage waveform output by the motor driver 21 to the switch unit 31 corresponds to a time-division synthesis of the voltage waveforms for the multiple motors 10. The second selection switch 35 of the switch unit 31 separates the synthesized voltage waveform through cyclic switching operation linked to the first selection switch 3, and supplies it to the motor 10 to which the motor controller 2 is assigned.

[0057] The motors 10 will now be described. In this embodiment, the motors 10 are configured as three-phase motors. Each motor 10 includes a stator and a mover.

[0058] The motor 10 of this embodiment is a linear motor in which a mover moves linearly (slides) relative to a stator.

[0059] The mover of the linear motor includes a permanent magnet, and the stator includes a coil. The mover is attached to a carriage 7 of a conveyance system. A plurality of stators are arranged along the movement path of the carriage 7. When the linear motor is a three-phase motor, the number of coils included in the stator of one motor 10 can be 3, 6, 9, etc. FIG. 1 shows a case where the number of motors 10 is five, but in a ground primary type linear motor system, a large number of stators (in other words, motors 10) are arranged side by side along the movement path of the carriage 7.

[0060] When power is supplied from the motor driver 21 to the coil of the motor 10, the coil becomes an electromagnet, which generates a repulsive or attractive force between the stator and the mover, causing the mover to move relative to the stator.

[0061] An encoder 41 is provided for each motor 10. The encoder 41 detects the operating state of the motor 10, specifically, the relative displacement of the mover with respect to the stator. The encoder 41 can be, for example, a magnetic sensor provided on the movement path of the mover. The magnetic sensor can detect the position of the mover with respect to the stator.

[0062] A rotary motor in which a mover (rotor) rotates relative to a stator can also be used as the motor 10. When the motor 10 is a rotary motor, the encoder 41 can be, for example, a known Hall element. The Hall element can detect the rotation angle of the mover.

[0063] The encoder 41 is electrically connected to the control unit 1. The control unit 1 can output a signal indicating the detected operating state of the motor 10 to the control unit 1.

[0064] Next, the allocation process of the motor controller 2 performed by the allocation unit 4 of the control unit 1 and the switching operation of the first selection switch 3 and the second selection switch 35 will be described.

[0065] Hereinafter, in order to identify each motor 10, they may be referred to by numbers, starting from the motor 10 on the left side shown in Fig. 1, such as motor #1, motor #2, .... As described above, the motors 10 are configured as linear motors, and the mover moves so as to pass through a number of stators (coils). The numbers of the motors 10 can be said to be numbers that essentially identify the stators.

[0066] Similarly, the encoders 41 may also be numbered and referred to, such as encoder #1, encoder #2, .... The encoders 41 are arranged to correspond to the coils of each motor 10. The number of the encoder 41 corresponds to the number of the motor 10 (stator).

[0067] Furthermore, in order to identify each motor controller 2, they may be referred to by an alphabetical name, such as motor controller #A, motor controller #B, etc., starting from the leftmost motor controller 2 shown in FIG.

[0068] The following description will be made with reference to the graph in Fig. 2. Fig. 2 shows the change in output of each motor controller 2 in relation to the detection of the bogie 7 by the encoder 41. Fig. 2 also shows the change in state of the first selection switch 3 and the second selection switch 35. In Fig. 2, the horizontal axis represents time. For the sake of simplicity, the example in Fig. 2 shows a case where the number of motor controllers 2 is two and the number of motors 10 (the number of coils) is four.

[0069] At time t0, the power supply is turned on for the encoder 41. At this time, it is assumed that the encoder #1 and the encoder #3 each detect the carriage 7.

[0070] When a bogie 7 is detected, the allocation unit 4 assigns appropriate identification information to identify each of the detected bogies 7. In this example, the allocation unit 4 assigns an identification number "1" to the bogie 7 detected by the encoder #3, and an identification number "2" to the bogie 7 detected by the encoder #1. Hereinafter, in order to identify these bogies 7, they may be referred to by their identification numbers, such as bogie [1] and bogie [2].

[0071] Although details will be described later, the identification information of the bogie 7 is used as a medium for the motor controller 2 to assign the bogie 7 to the motor 10. It is sufficient for the identification information given to the bogie 7 to be able to identify each of the bogies 7 that are driven simultaneously by the motor system 100. In other words, the identification information of the bogie 7 does not need to be given so as to be able to uniquely identify all bogies 7, including those that are not detected by the encoder 41.

[0072] It is assumed that at time t1, an instruction to run the two carriages 7 detected by the encoder 41 is input from a host computer to the control unit 1.

[0073] The allocation unit 4 immediately associates motor controller #A with bogie [1] and motor controller #B with bogie [2]. Furthermore, the allocation unit 4 associates encoder #3 with bogie [1] and encoder #1 with bogie [2]. All of these associations are performed on a one-to-one basis.

[0074] The motor controller 2 is assigned to the motor 10 through the two correspondences via the bogie 7. Specifically, the motor controller #A is essentially assigned to the motor #3 to which the encoder #3 belongs via the bogie [1]. Similarly, the motor controller #B is essentially assigned to the motor #1 to which the encoder #1 belongs via the bogie [2].

[0075] After time t1, the switching control unit 5 switches the first selection switch 3 so that the output of the motor controller #A and the output of the motor controller #B are cyclically switched. Correspondingly, the switching control unit 5 switches the second selection switch 35 so that the motor #3 is the target motor when the output of the motor controller #A is selected, and the motor #1 is the target motor when the output of the motor controller #B is selected.

[0076] In other words, the switching control unit 5 selects the output of the motor controller 2 with the first selection switch 3, and at the same time selects the output destination of the motor driver 21 with the second selection switch 35 so that the output destination of the motor driver 21 becomes the coil of the motor 10 to which the selected motor controller 2 is assigned. The mutually linked switching of the first selection switch 3 and the second selection switch 35 is repeated in a short period of time.

[0077] As a result, motor #3 is driven under the control of motor controller #A to run cart [1], and at the same time, motor #1 is driven under the control of motor controller #B to run cart [2].

[0078] Since motor controller #A and motor controller #B are different from each other, position control, speed control, etc. of motor #3 and motor #1 are performed independently of each other.

[0079] After that, as a result of the bogie [1] traveling, at the timing of time t2, the encoder #3 no longer detects the bogie 7, and at the same time, the encoder #4 detects the bogie 7. In this case, the allocation unit 4 cancels the association of the encoder #3 with the bogie [1], and instead associates the encoder #4. Accordingly, the allocation of the motor controller #A to the motor #3 is canceled, and instead, the motor controller #A is assigned to the motor #4.

[0080] As a result, from time t2 onwards, motor controller #A drives motor #4 to run cart [1], and at the same time, motor controller #B drives motor #1 to run cart [2].

[0081] Next, as a result of the bogie [2] traveling, at the timing of time t3, the encoder #1 does not detect the bogie 7, and at the same time, the encoder #2 detects the bogie 7. In this case, the allocation unit 4 cancels the association of the encoder #1 with the bogie [2], and instead associates the encoder #2 with it. Accordingly, the allocation of the motor controller #B to the motor #1 is canceled, and instead, the motor controller #B is assigned to the motor #2.

[0082] As a result, from time t3 onwards, motor controller #A drives motor #4 to run the cart [1], and at the same time, motor controller #B drives motor #2 to run the cart [2].

[0083] Next, suppose that as a result of the bogie [1] traveling, at the timing of time t4, the encoder #4 no longer detects the bogie 7. This may be caused, for example, by the bogie 7 entering an area outside its jurisdiction when the travel area of ​​the bogie 7 is divided into multiple areas and shared by multiple motor systems 100. In this case, the allocation unit 4 cancels the association of the encoder #4 with the bogie [1] and the association of the motor controller #A with the bogie [1]. Accordingly, the allocation of the motor controller #A to the motor #1 is cancelled. The motor controller #A, which has lost its subject to control, stops control.

[0084] As a result, after time t4, the switching control unit 5 operates the first selection switch 3 so that only the motor controller #B performs output. Correspondingly, the switching control unit 5 operates the second selection switch 35 so that only the motor #2 to which the motor controller #B is assigned becomes the target motor.

[0085] Therefore, after time t4, motor #2 can be driven under the control of motor controller #B to run cart [2].

[0086] Next, as a result of the bogie [2] traveling, at the timing of time t5, the encoder #2 no longer detects the bogie 7, and at the same time, the encoder #3 detects the bogie 7. In this case, the allocation unit 4 cancels the association of the encoder #2 with the bogie [2], and instead associates the encoder #3, in a manner substantially similar to that described at time t2. Accordingly, the allocation of the motor controller #B to the motor #2 is canceled, and instead, the motor controller #B is assigned to the motor #3.

[0087] As a result, after time t5, motor #3 can be driven under the control of motor controller #B to run the bogie [2].

[0088] Next, for example, suppose that a vehicle 7 travels from an area outside the jurisdiction, and as a result, the encoder #1 newly detects the vehicle 7 at time t6.

[0089] When the cart 7 is detected, the assigning unit 4 assigns identification information to identify the detected cart 7. The example of Fig. 2 shows a case where the identification number "3" is assigned to the cart 7.

[0090] Next, the allocation unit 4 associates the motor controller #A, which has been stopped since time t4, with the bogie [3]. Furthermore, the allocation unit 4 associates the encoder #1 with the bogie [3]. As a result, the motor controller #A is assigned to the motor #1.

[0091] After time t6, the switching control unit 5 switches the first selection switch 3 so that the output of the motor controller #A and the output of the motor controller #B are cyclically switched. Correspondingly, the switching control unit 5 switches the second selection switch 35 so that the motor #1 is the target motor when the output of the motor controller #A is selected, and the motor #3 is the target motor when the output of the motor controller #B is selected.

[0092] As a result, motor #1 can be driven under the control of motor controller #A to run the cart [3], and at the same time, motor #3 can be driven under the control of motor controller #B to run the cart [2].

[0093] For example, in a ground primary linear motor system, the number of stator coils (in other words, motors 10) may reach several hundred. Correspondingly, it is technically possible to configure the control unit 1 to include several hundred motor controllers 2. In this case, however, the power allocated to each motor is several hundredths, making it difficult to generate a strong thrust in the coils. Furthermore, a configuration including many motor controllers 2 requires high computer performance from the control unit 1, which causes an increase in hardware costs.

[0094] In this regard, the motor system 100 of this embodiment is configured such that an upper limit is set for the number of motors 10 that can be controlled and driven simultaneously (in other words, the number of carts 7), and the control unit 1 is provided with a number of motor controllers 2 equal to that upper limit. This makes it possible to increase the amount of power that can be used per motor 10. Furthermore, by limiting the number of motor controllers 2, it is possible to conserve hardware resources. As a result, it is possible to reduce the cost of the system.

[0095] In the linear motor system, each carriage 7 travels so as to pass through the coils of the multiple motors 10 in succession. To achieve this, the motors 10 driving the carriages 7 are changed in succession. The control switching for the carriages 7 to change between the motors 10 is performed based on a known algorithm. In this embodiment, cyclic switching of the output of the motor controller 2 and dynamic change of the allocation of the motor controllers 2 are combined. This configuration can be said to be highly compatible with the motor changeover algorithm of a moving body that an existing ground primary linear motor system has.

[0096] The motor driver 21 can also be modified to include the same number of current control units 25 as the number of motor controllers 2. This modification will be described below with reference to Fig. 3. In the description of this modification, the same or similar members as those in the above-described embodiment are given the same reference numerals in the drawings, and the description may be omitted. The same applies to the configuration example in Fig. 4 described later.

[0097] 3, the motor driver 21x includes three current control sections 25. The output of each motor controller 2 is input to a corresponding current control section 25. In order to pass the outputs of the multiple current control sections 25 to the inverter control section 26, the first selection switch 3 is provided in the motor driver 21x instead of the control section 1.

[0098] As with the configuration of Fig. 1, the motor system 100x of this modified example can also realize efficient use of power by limiting the number of simultaneously driven carts 7. In this modified example, a current control section 25 is provided corresponding to each of the multiple motor controllers 2, and therefore the controllability of the motor 10 is better than that of the configuration of Fig. 1. On the other hand, in this modified example, the motor driver 21 needs to have multiple current control sections 25 and a special configuration for selecting the output of each current control section. Therefore, it becomes difficult to use a general-purpose motor driver that is widely used as the motor driver 21.

[0099] 1, one current control unit 25 included in the motor driver 21 operates in common to control multiple motors 10. Therefore, a general-purpose motor driver 21 capable of controlling one motor can be used as is in the motor system 100.

[0100] In the embodiment shown in FIG. 1, a time-division synthesis of the outputs of a plurality of speed control sections 17 is input to one current control section 25. Usually, the control law of the current control section 25 includes a differential term and an integral term. If control dependent on past information is included in this way, the control of one motor 10 will be affected by past information on another motor 10. Therefore, in this embodiment, the current control section 25 is configured to perform only proportional control, and not differential control or integral control. This configuration can be realized by setting the motor driver 21 to substantially disable the differential term and integral term when the general-purpose motor driver 21 is operated in the current control mode.

[0101] If the current control unit 25 does not perform integral control, steady-state error remains in the current control. Therefore, it is possible to provide a current integration unit 18 in each motor controller 2 in the control unit 1, as shown in the configuration example of FIG.

[0102] The current integrator 18 obtains a current deviation by subtracting a current value detected by the motor driver 21 from a current command that is an output of the speed controller 17. The current value can be acquired by a current sensor 51 arranged on the output side of the inverter 27, as shown in FIG. 4. The obtained current deviation is input to an integrator. The current integrator 18 outputs a voltage value equivalent to the output of the integrator multiplied by an appropriate gain Ki.

[0103] The output of the current integrator 18 is input to the first selection switch 3. When the first selection switch 3 inputs the output of the selected motor controller 2 to the motor driver 21, it also operates to input the output of the current integrator 18 included in the motor controller 2 to the motor driver 21 at the same time.

[0104] The current control unit 25 of the motor driver 21 performs only the proportional control as described above, based on the current command output by the speed control unit 17 of the motor controller 2. However, in the current control unit 25, the voltage value output by the current integration unit 18 is added to the voltage value, which is the manipulated variable output by the proportional controller.

[0105] Current control unit 25 obtains a current deviation by subtracting a current value detected in motor driver 21 from a current command that is an output of speed control unit 17. Current control unit 25 multiplies the obtained current deviation by an appropriate gain Kp, and then adds the voltage input from current integration unit 18. Current control unit 25 outputs the voltage obtained in this manner to inverter control unit 26 as a control signal.

[0106] As a result, the problem of steady-state deviation remaining can be resolved. Since the current integrator 18 is provided for each motor controller 2, the control of the motor 10 is not affected by past information on other motors 10. Furthermore, since the current integrator 18 is provided in the control unit 1, the motor driver 21 can be modified simply by adding a configuration for adding a voltage value to a general-purpose motor driver 21. In other words, since the only change in the configuration is to add an integral term, for example, there is no need to manage parameters (e.g., gain and control period, etc.) associated with integral calculation, resetting the integral value, or limiting. Therefore, it is easy to apply a general-purpose motor driver 21.

[0107] As described above, the motor system 100 of this embodiment includes a plurality of motors 10, a motor driver 21, a switch unit 31, an output control unit 6, and a switching control unit 5. The motor driver 21 supplies power to generate driving force to the plurality of motors 10. The switch unit 31 selectively switches the target motor, which is the target of the supply of power output by the motor driver 21, between the plurality of motors 10. The output control unit 6 has a plurality of motor controllers 2 that control one motor 10, and controls the motor driver 21 so that the motor driver 21 outputs power based on the output of each motor controller 2. The switching control unit 5 controls the switch unit 31 so that the target motor is cyclically switched between the motors 10 out of the plurality of motors 10, the number of which is equal to or less than the number of the motor controllers 2.

[0108] This allows a single motor driver 21 to independently control a plurality of motors 10. By setting the number of motor controllers 2 to be less than the number of motors 10 connected to the motor driver 21, the number of motor controllers 2 can be reduced and the configuration can be simplified. Furthermore, by limiting the number of motors 10 that are driven simultaneously, the power allocated from the motor driver 21 to each motor can be increased.

[0109] The motor system 100 of this embodiment also includes a plurality of bogies 7 and an encoder 41. The encoder 41 detects the position of the bogie 7. The plurality of motors 10 move the plurality of bogies 7. The allocation unit 4 included in the output control unit 6 allocates the motor controller 2 to a motor 10 selected from the plurality of motors 10 and cancels the allocation based on the detection result of the encoder 41. The output control unit 6 controls the motor driver 21 so that the motor driver 21 outputs power based on the output of the motor controller 2 allocated to one of the plurality of motors 10. The switching control unit 5 controls the switch unit 31 so that the target motor is cyclically switched between the motors 10 to which the motor controllers 2 are allocated, and so that power equivalent to the output of the motor controller 2 is output to the motor 10 to which the motor controller 2 is allocated.

[0110] As a result, when the carriage 7 moves across multiple motors 10, the motor controller 2 can switch between the motors 10 assigned thereto based on detection by the encoder 41. This allows the multiple motors 10 to operate in coordination. This configuration is particularly suitable for ground primary type linear motor systems.

[0111] Furthermore, in the motor system 100 of this embodiment, each of the multiple motor controllers 2 includes a position control unit 16 that controls the position of the motor 10.

[0112] This allows the positions of the multiple motors 10 to be controlled independently.

[0113] Furthermore, in the motor system 100 of this embodiment, each of the multiple motor controllers 2 includes a speed control section 17 that controls the speed of the motor 10.

[0114] This allows the speeds of multiple motors 10 to be controlled independently.

[0115] In the motor system 100 of this embodiment, the speed control section 17 is provided in the control section 1 which is a device separate from the motor driver 21.

[0116] In this way, since the multiple speed control units 17 are provided in a device different from the motor driver 21, there is no need for the motor driver 21 to have a special structure. Therefore, it is easy to apply a general-purpose motor driver for driving one motor.

[0117] 1, the motor driver 21 in the motor system 100 of this embodiment includes a current control unit 25 that controls the current flowing through the motor 10. The outputs of the speed control units 17 of the multiple motor controllers 2 are input to the current control unit 25 while being cyclically switched. In the current control unit 25, control that depends on past information is disabled.

[0118] This makes it possible to prevent past information regarding the motor 10 from affecting the control of other motors 10. As a result, unintended operation of the motor 10 can be prevented.

[0119] 4, each of the multiple motor controllers 2 includes a current integrator 18. The current integrator 18 integrates the deviation between a current command that is the output of the motor controller 2 and a current that flows through the motor 10 that is the target of control by the motor controller 2. The motor driver 21 adds the proportional control output in the current control unit 25 and the input from the current integrator 18, and outputs power based on the result of the addition.

[0120] This makes it possible to realize integral control of the current of each motor 10, thereby reducing steady-state deviation. A current integrator 18 is provided for each motor controller 2, thereby making it possible to prevent past current deviations for a motor 10 from affecting the control of other motors 10. By providing the current integrator 18 in hardware (e.g., control unit 1) separate from the motor driver 21, there is no need for the motor driver 21 to have a special structure.

[0121] Although the preferred embodiment of the present invention has been described above, the above configuration can be modified, for example, as follows. Each modification may be made alone, or multiple modifications may be made in any combination.

[0122] The number of motors 10 connected to one motor driver 21, 21x can be determined arbitrarily. The same applies to the number of motor controllers 2 included in the control unit 1.

[0123] At least one of the allocation unit 4 and the switching control unit 5 may be modified so as to be included in the motor driver 21 or the switch unit 31.

[0124] The encoder 41 may be configured to output information on the detected position of the mover to the control unit 1 via the switch unit 31 and the motor driver 21. In this case, the connection between the encoder 41 and the control unit 1 can be simplified.

[0125] The allocation unit 4 may directly allocate the motor controllers 2 to the motors 10 without using the carriage 7 as an intermediary.

[0126] The motor controller 2 including the speed control section 17 may be provided in the same device as the motor driver 21.

[0127] The position control unit 16 and the motor driver 21 may be provided in the same device.

[0128] As the motor drivers 21 and 21x, motor drivers having special configurations, for example, that have been modified, may be used.

[0129] The motor driver 21 and the switch unit 31 may be realized as physically separate devices, or may be realized as a single device.

[0130] As the motor 10, a two-phase motor may be used instead of a three-phase motor.

[0131] Each of the motors 10 may be a rotary motor. For example, the present invention may be applied to a roller conveyor in which rotary rollers are arranged side by side, and each of the rotary rollers is driven by a rotary motor.

[0132] The motor systems 100 and 100x can also be applied to appropriate systems other than the transport system.

[0133] At least the following technical ideas can be grasped from the embodiment and its modified examples described above.

[0134] [Item 1] Multiple motors and A motor driver that generates and outputs a drive waveform by PWM control for generating a drive force for the plurality of motors; a switch unit that selectively switches a target motor to which the power output by the motor driver is to be supplied among the plurality of motors; Equipped with the switch unit is controlled by a switching control unit so that the target motor is cyclically switched among the plurality of motors; A carrier cycle of the PWM control includes a high-level period during which the PWM output is at a high level and a low-level period during which the PWM output is at a low level, The motor system according to claim 1, wherein the switching control unit controls the switch unit so that the switch unit switches the target motor during the low level period.

[0135] [Item 2] The motor system according to item 1, A motor system characterized in that the switching control unit controls the switch unit so that the switch unit switches the target motor at a timing where the phase of the carrier cycle differs by 180° from the center timing of the high level period.

[0136] [Item 3] The motor system according to item 1 or 2, the switching control unit controls the switch unit so that the target motor is switched at every predetermined switching period; A motor system characterized in that the carrier period of the PWM control and the switching period are synchronized.

[0137] [Item 4] The motor system according to any one of items 1 to 3, a voltage detection unit that detects a voltage output from the motor driver; The motor system is characterized in that the switching control unit determines a switching timing included in the low level period based on the detection result of the voltage detection unit, and controls the switch unit so that the switch unit switches the target motor at the switching timing.

[0138] [Item 5] The motor system according to item 4, Each of the plurality of motors includes a multi-phase coil; The PWM control performed by the motor driver is performed on each of the coils of the multiple phases, The switching control unit is determining a center timing of a past high level period of a PWM output for at least one of the phases; A motor system comprising: a motor control unit that determines the switching timing based on the central timing.

[0139] [Item 6] The motor system according to item 5, The switching control unit is determining a center timing of a past high level period of a PWM output for two or more of the plurality of phases; A motor system comprising: a motor control unit that determines the switching timing based on the central timing determined for two or more phases;

[0140] [Item 7] The motor system according to any one of items 1 to 6, Each of the plurality of motors includes a multi-phase coil; The PWM control performed by the motor driver is performed on each of the coils of the multiple phases, A motor system characterized in that the switching control unit controls the switch unit so that the switch unit switches the target motor during a period in which PWM outputs of all of the multiple phases are at a low level. [Explanation of symbols]

[0141] 1. Control section 2 Motor Controller 5 Switching control section 6 Output control section 7 Cart (mobile) 10 Motor 17 Speed ​​control section 18 Current integration section 21,21x Motor Driver 25 Current control section 31 Switch section 41 Encoder (position detection unit) 100,100x motor system

Claims

1. A plurality of motors; a motor driver that supplies power to the plurality of motors to generate driving forces; a switch unit that selectively switches a target motor to which the power output by the motor driver is to be supplied among the plurality of motors; an output control unit that has a plurality of motor controllers that control one of the motors and controls the motor driver so that the motor driver outputs power based on the output of each of the motor controllers; a switching control unit that controls the switch unit so that the target motor is cyclically switched among the motors among the plurality of motors, the number of which is equal to or less than the number of the motor controllers; A motor system comprising:

2. 2. The motor system of claim 1, A plurality of moving bodies; A position detection unit that detects the position of the moving object; Equipped with the plurality of motors move the plurality of moving bodies, The output control unit is assigning and canceling the motor controller to the motor selected from the plurality of motors based on a detection result of the position detection unit; controlling the motor driver so that the motor driver outputs power based on an output of the motor controller assigned to any one of the plurality of motors; A motor system characterized in that the switching control unit controls the switch unit so that the target motor is cyclically switched between the motors to which the motor controllers are assigned, and so that power equivalent to the output of the motor controller is output to the motor to which the motor controller is assigned.

3. 2. The motor system of claim 1, A motor system, wherein each of the plurality of motor controllers includes a position control unit that controls a position of the motor.

4. 2. The motor system of claim 1, A motor system, wherein each of the plurality of motor controllers includes a speed control section that controls a speed of the motor.

5. 5. The motor system according to claim 4, A motor system characterized in that the speed control unit is provided in a device separate from the motor driver.

6. 5. The motor system according to claim 4, The motor driver includes a current control unit that controls a current flowing through the motor, The current control unit receives outputs of the speed control units of the plurality of motor controllers while switching them cyclically; A motor system, characterized in that in the current control unit, control that depends on past information is disabled.

7. 7. The motor system according to claim 6, Each of the plurality of motor controllers includes a current integration unit; the current integration unit integrates a deviation between a current command that is an output of the motor controller and a current that flows through the motor that is an object of control by the motor controller; A motor system characterized in that the motor driver adds the proportional control output of the current control unit and the input from the current integration unit, and controls the motor driver so that the motor driver outputs power based on the result of this addition.

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