Electric drive system

Abstract

To provide an electric drive device that enables a vehicle to keep travelling as long as possible.SOLUTION: An electric drive device, which is applied to an unmanned carrier 10, comprises driving units 20 that rotate driving wheels 12. The driving unit 20 has a plurality of system devices, a rotor constituting a motor, which is common to the system devices, and a housing formed in a tubular shape which is long in an extending direction of a shaft of the rotor, in which the system devices and the rotor are housed in a tubular space. The system devices have stator winding wire constituting the motor and inverters electrically connected to the stator winding wire respectively. The driving units 20 have control parts that perform switching control of the inverters in order to rotate the driving wheels 12 by rotating the rotor.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electric drive Place device.

Background Art

[0002] Conventionally, electric drive devices for driving vehicles are known. An electric drive device is applied to automated guided vehicles used in factories, for example, as described in Patent Document 1.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] The electric drive device includes a motor having a rotor and stator windings, an inverter electrically connected to the stator windings, and a control unit that performs switching control of the inverter. When the control unit performs switching control of the inverter, the rotor rotates, and the rotational power of the rotor is transmitted to the drive wheels, whereby the vehicle travels.

[0005] Here, if an abnormality occurs in the inverter or the stator windings, there is a concern that the traveling of the vehicle cannot be continued.

[0006] The present invention provides an electric drive device capable of continuing the traveling of the vehicle as much as possib Place le, and it is a main object of the present invention to provide such an electric drive device.

Means for Solving the Problem

[0007] The present invention relates to an electric drive device for driving a vehicle, comprising a drive unit that rotates drive wheels of the vehicle, the drive unit: Multiple system devices, A motor is configured, and a rotor common to each of the aforementioned system devices, The rotor has a long tubular shape in the direction in which its shaft extends, and the tubular space contains a housing that accommodates the various system devices and the rotor. It has, Each of the aforementioned system devices, The stator windings that constitute the motor, An inverter electrically connected to the stator winding, It has, The drive unit includes a control unit that performs switching control of each inverter in order to rotate the rotor and thereby rotate the drive wheel.

[0008] The drive unit of the present invention comprises multiple power supply units and a rotor common to each power supply unit. Each power supply unit is equipped with a stator winding and an inverter. Therefore, even if a malfunction occurs in the inverter or stator winding of any of the power supply units, the rotor can be rotated and the drive wheels can be rotated by the switching control of the inverter of a power supply unit that is not malfunctioning. This allows the vehicle to continue running for as long as possible.

[0009] Furthermore, in this invention, each system device and rotor are housed within the tubular space of the housing. Therefore, the wiring that electrically connects the stator windings and the inverter is also housed within the housing. This simplifies the wiring in a configuration that includes multiple system devices having stator windings and inverters. [Brief explanation of the drawing]

[0010] [Figure 1] Overall configuration diagram of an automated guided vehicle according to the first embodiment. [Figure 2] A diagram showing the drive unit. [Figure 3] A diagram showing the internal structure of a motor. [Figure 4] This diagram shows the motor section in the cross-sectional view along line 4-4 in Figure 3. [Figure 5] A diagram showing the electrical configuration of a drive unit. [Figure 6] A flowchart showing the processing procedure for travel control of an automated guided vehicle. [Figure 7] A diagram showing an example of fail-safe control when an abnormality occurs. [Figure 8] A flowchart showing the processing procedure for travel control of an automated guided vehicle according to a second embodiment. [Figure 9] A diagram showing an example of fail-safe control when an abnormality occurs. [Figure 10] A flowchart showing the processing procedure for travel control of an automated guided vehicle according to a third embodiment. [Figure 11] An overall configuration diagram of an electric wheelchair according to a fourth embodiment. [Figure 12] An overall configuration diagram of a senior electric scooter according to a fifth embodiment. [Figure 13] A diagram showing the electrical configuration of a drive unit according to another embodiment. MODE FOR CARRYING OUT THE INVENTION

[0011] <First Embodiment> Hereinafter, a first embodiment embodying the electric drive device according to the present invention will be described with reference to the drawings. The electric drive device is applied to small mobility. The small mobility of the present embodiment is a vehicle that travels at a low speed, for example, 10 km / h or less, and specifically is an automated guided vehicle (AGV), which is an electric vehicle used in factories.

[0012] As shown in FIG. 1 and FIG. 2, the automated guided vehicle (10) includes a vehicle body (11) and a plurality of drive wheels (12). In the present embodiment, the plurality of drive wheels (12) consist of a right drive wheel (12R) and a left drive wheel (12L) arranged side by side with the right drive wheel (12R) in the vehicle width direction. The automated guided vehicle (10) is provided with three sets of the right drive wheel (12R) and the left drive wheel (12L).

[0013] The vehicle body 11 is equipped with an electric drive unit for moving the automated guided vehicle 10, a power storage unit 15, and a higher-level ECU 16. The power storage unit 15 is, for example, a secondary battery such as a lithium-ion battery. In this embodiment, the power storage unit 15 is divided into a first power storage unit 15A and a second power storage unit 15B in order to make the configuration redundant.

[0014] The electric drive system includes a drive unit 20 corresponding to each drive wheel 12. In this embodiment, the configuration of each drive unit 20 is basically the same. The drive unit 20 includes a motor 30. The motor 30 will be described below with reference to Figures 3 and 4. Figure 4 is a cross-sectional view taken along line 4-4 of Figure 3.

[0015] The motor 30 comprises a rotor 31 including field poles (e.g., permanent magnets), a shaft 32 fixed to the rotor 31, and a stator 40 positioned radially outward from the rotor 31. The stator 40 comprises a stator core and stator windings 41 wound around the stator core (see Figure 5).

[0016] The motor 30 is equipped with a housing 50. The housing 50 comprises a tubular portion 51, a wheel-side cover portion 52, a connecting portion 53, and a vehicle body-side cover portion 54. The tubular portion 51 is long in the direction in which the shaft 32 extends, and is specifically cylindrical. The wheel-side cover portion 52 is provided at the first end of the tubular portion 51 in the longitudinal direction, and the connecting portion 53 is provided at the second end. The rotor 31 and stator 40 are housed in the tubular (cylindrical) space enclosed by the tubular portion 51, the wheel-side cover portion 52, and the connecting portion 53. The stator 40 is provided on the inner circumferential surface of the tubular portion 51. Note that the housing 50 is not limited to having a cylindrical cross-section; for example, it may have a rectangular cross-section.

[0017] A wheel-side opening 52a is formed in the wheel-side cover portion 52, and a first bearing 55a is provided in the wheel-side opening 52a. A vehicle-side opening 53a is formed in the connecting portion 53, and a second bearing 55b is provided in the vehicle-side opening 53a. In this embodiment, each bearing 55a, 55b is a rolling bearing comprising an inner ring, an outer ring, and rolling elements (e.g., rollers). The first end of the shaft 32 is rotatably supported by the first bearing 55a, and the second end of the shaft 32 is rotatably supported by the second bearing 55b. A drive wheel 12 is connected to the first end of the shaft 32. The shaft 32 functions as a drive shaft that rotates the drive wheel 12.

[0018] Of the connection portion 53, a vehicle body side cover portion 54 is provided on the side of the housing 50 opposite to the tubular portion 51 in the longitudinal direction. A control board 60 is arranged in the space enclosed by the connection portion 53 and the vehicle body side cover portion 54. In this embodiment, the control board 60 is positioned so that its surface is perpendicular to the direction in which the shaft 32 extends. A connector opening 54a is formed in the vehicle body side cover portion 54. A connector 61, electrically connected to the control board 60, is inserted through the connector opening 54a. The connector 61 includes a power connector and a communication connector.

[0019] Thus, in this embodiment, the housing 50 houses the control board 60 on which the rotor 31, stator 40, and inverter (described later) are mounted. Therefore, the wiring that electrically connects the stator winding 41 and the inverter can also be housed in the housing 50, simplifying the configuration of the electric drive device.

[0020] The first end of the shaft 32 and the drive wheel 12 may be connected via a reduction gear. The reduction gear is, for example, a reduction gear equipped with a planetary gear mechanism or a cycloidal gear mechanism, which increases the output torque of the motor 30 and outputs it to the drive wheel 12. In this case, the reduction gear may also be housed in the housing 50.

[0021] Next, the electrical configuration of each drive unit 20 will be explained using Figure 5.

[0022] Each drive unit 20 has a motor 30 with two stator windings 41 for each rotor 31. Each stator winding 41 is individually equipped with an inverter, control unit, and various sensors. This ensures that even if a malfunction occurs in one of the systems, the remaining systems can continue to supply torque to the motor 30. Each drive unit 20 includes a first system device 100 having a first stator winding 103, which is the stator winding 41 of the first system, and a second system device 200 having a second stator winding 203, which is the stator winding 41 of the second system. The first system device 100 and the second system device 200 are housed in a housing 50.

[0023] The first system device 100 includes a first inverter 101. The first inverter 101 includes three phase upper and lower arm switches SW. In this embodiment, the switches SW are voltage-controlled semiconductor switching elements, specifically SiC N-channel MOSFETs. Therefore, in the switches SW, the high-potential terminal is the drain and the low-potential terminal is the source. The switches SW have a body diode. Note that the switches SW may also be, for example, IGBTs. In this case, in the switches SW, the high-potential terminal is the collector and the low-potential terminal is the emitter.

[0024] In each phase, the drain of the upper arm switch SW is connected to the first terminal of the first smoothing capacitor 102. In each phase, the source of the upper arm switch SW is connected to the drain of the lower arm switch SW. In each phase, the source of the lower arm switch SW is connected to the second terminal of the first smoothing capacitor 102. In each phase, the source of the upper arm switch SW and the drain of the lower arm switch SW are connected to the first terminal of the first stator winding 103. The second terminal of the first stator winding 103 in each phase is connected at the neutral point.

[0025] The first terminal of the first smoothing capacitor 102 is connected to the positive terminal of the first energy storage unit 15A, which constitutes the energy storage unit 15, via a power connector included in the connector 61 and a power cable (not shown). The second terminal of the first smoothing capacitor 102 is connected to the negative terminal of the first energy storage unit 15A via a power connector and a power cable (not shown).

[0026] The first system device 100 includes a first disconnection switch 104 that connects the first inverter 101 and the first stator winding 103. The first disconnection switch 104 is provided individually for each phase. The first disconnection switch 104 is, for example, a normally open semiconductor switch or a mechanical relay.

[0027] The first system device 100 comprises a first control unit 105, a first current sensor 106, a first rotation angle sensor 107, and a first drive IC 108. In this embodiment, the first drive IC 108 is provided individually for each switch SW. The first current sensor 106 detects the current (phase current) flowing through the first stator winding 103. The first rotation angle sensor 107 detects the rotation angle position (electrical angle) of the rotor 31. The detected values ​​from the first current sensor 106 and the first rotation angle sensor 107 are input to the first control unit 105.

[0028] The first control unit 105 is mainly composed of a microcontroller. Based on each detected value, the first control unit 105 controls the switching of each switch SW that constitutes the first inverter 101 in order to control the control amount of the motor 30 corresponding to the first stator winding 103 to a first command value. Since the control amount in this embodiment is torque, the first command value is the first command torque.

[0029] More specifically, the first control unit 105 generates drive signals corresponding to the upper and lower arm switches in order to alternately turn on the upper arm switch SW and the lower arm switch SW in each phase. The first control unit 105 outputs the generated drive signals to the first drive IC 108. The first control unit 105, the first drive IC 108, the first inverter 101, and the first smoothing capacitor 102 are provided on a control board 60 housed in a housing 50.

[0030] The second system device 200, like the first system device 100, includes a second inverter 201, a second smoothing capacitor 202, a second stator winding 203, a second cutoff switch 204, a second control unit 205, a second current sensor 206, a second rotation angle sensor 207, and a second drive IC 208. The configuration of the second system device 200 is basically the same as that of the first system device 100. Therefore, a detailed explanation of the second system device 200 will be omitted as appropriate.

[0031] The second inverter 201 is connected to the second energy storage unit 15B, which constitutes the energy storage unit 15.

[0032] The second control unit 205 is mainly composed of a microcontroller. Based on each detected value, the second control unit 205 controls the switching of each switch SW that makes up the second inverter 201 in order to control the torque of the motor 30 corresponding to the second stator winding 203 to the second command torque. The output torque of the motor 30 is controlled to the sum of the first command torque and the second command torque.

[0033] More specifically, the second control unit 205 generates drive signals corresponding to the upper and lower arm switches in order to alternately turn on the upper arm switch SW and the lower arm switch SW in each phase. The second control unit 205 outputs the generated drive signals to the second drive IC 208. The second control unit 205, the second drive IC 208, the second inverter 201, and the second smoothing capacitor 202 are provided on the control board 60.

[0034] Furthermore, the switching frequencies of the second inverter 201 and the first inverter 101 are set to frequencies higher than the range of human hearing. This ensures current control while reducing noise and vibration (NV).

[0035] The first control unit 105 and the second control unit 205 are configured to communicate with each other. Therefore, for example, the detected values ​​of each current sensor 106, 206 and each rotation angle sensor 107, 207 can be exchanged between the control units 105, 205.

[0036] Even if an abnormality occurs in either the first system device 100 or the second system device 200, the driving control of the automated guided vehicle 10 can be continued by the system device that is not experiencing any abnormalities.

[0037] Each control unit 105, 205 communicates with the higher-level ECU 16 via the communication connector that constitutes the connector 61. The higher-level ECU 16 transmits command torques to each control unit 105, 205 of each drive unit 20 via the communication connector so that desired control, such as driving control of the automated guided vehicle 10, can be realized. Hereinafter, the drive unit that rotates the right drive wheel 12R will be referred to as the right-side unit 20R, and the drive unit that rotates the left drive wheel 12L will be referred to as the left-side unit 20L.

[0038] This section describes the normal control for straight-line travel, turning, and braking of the automated guided vehicle (AGV) 10.

[0039] When the higher-level ECU 16 determines that the automated guided vehicle 10 is instructed to travel in a straight line, it sends a command torque to each right-side unit 20R and each left-side unit 20L so that each right-side drive wheel 12R and each left-side drive wheel 12L rotates in the same direction and the rotation speed of each right-side drive wheel 12R and each left-side drive wheel 12L are the same. In each unit 20R, 20L, the first control unit 105 calculates half of the received command torque as the first command torque and performs switching control of the first inverter 101 so that the torque corresponding to the first stator winding 103 becomes the first command torque. In each unit 20R, 20L, the second control unit 205 calculates half of the received command torque as the second command torque and performs switching control of the second inverter 201 so that the torque corresponding to the second stator winding 203 becomes the second command torque.

[0040] When the higher-level ECU 16 determines that the automated guided vehicle 10 is instructed to turn to the right, it sends command torques to each right-side unit 20R and each left-side unit 20L such that each right drive wheel 12R and each left drive wheel 12L rotates in the same direction, and the rotational speed of each right drive wheel 12R, which corresponds to the inner wheel, is lower than the rotational speed of each left drive wheel 12L, which corresponds to the outer wheel.

[0041] When the higher-level ECU 16 determines that the automated guided vehicle 10 is instructed to turn left, it sends command torques to each right-side unit 20R and each left-side unit 20L such that each right drive wheel 12R and each left drive wheel 12L rotates in the same direction, and the rotational speed of each left drive wheel 12L, which corresponds to the inner wheel, is lower than the rotational speed of each right drive wheel 12R, which corresponds to the outer wheel.

[0042] Furthermore, the higher-level ECU 16 can also transmit command torques to each right-side unit 20R and each left-side unit 20L so that each right-side drive wheel 12R and each left-side drive wheel 12L rotate in opposite directions. In this case, the automated guided vehicle 10 will perform a pivot turn.

[0043] When the higher-level ECU 16 determines that braking of the automated guided vehicle 10 is instructed, it sends command torques to each right-side unit 20R and each left-side unit 20L to generate braking torque in the motors 30 of each drive unit 20. As a result, braking force is applied to each drive wheel 12 of the automated guided vehicle 10, and the automated guided vehicle 10 subsequently comes to a stop.

[0044] The first control unit 105, the second control unit 205, and the higher-level ECU 16 are equipped with microcontrollers, and the functions provided by each microcontroller can be provided by software recorded in a physical memory device and the computer that executes it, by software only, by hardware only, or by a combination thereof. For example, when a microcontroller is provided by an electronic circuit which is hardware, it can be provided by a digital circuit including a large number of logic circuits, or by an analog circuit. For example, a microcontroller executes a program stored in a non-transitory tangible storage medium which serves as its own memory unit. The program includes, for example, a driving control processing program as shown in Figure 6. When the program is executed, the method corresponding to the program is executed. The memory unit is, for example, a non-volatile memory. The program stored in the memory unit can be updated via a network such as the Internet, such as OTA (Over The Air).

[0045] In each drive unit 20, an abnormality may occur in either the first system device 100 or the second system device 200. Even in this case, in this embodiment, fail-safe control is implemented to allow the automated guided vehicle 10 to continue running as much as possible. This suppresses the occurrence of situations where the factory production line stops.

[0046] Using Figure 6, the processing procedure for the driving control of the automated guided vehicle 10, including the fail-safe control described above, will be explained. The processing shown in Figure 6 is executed by the higher-level ECU 16.

[0047] In step S10, each drive unit 20 determines whether an abnormality has occurred in either the first system device 100 or the second system device 200. Specifically, if each drive unit 20 determines that an abnormality has occurred in at least one of the following: the first inverter 101, the first cutoff switch 104, the first stator winding 103, the first control unit 105, the first current sensor 106, and the first rotation angle sensor 107, then it is determined that an abnormality has occurred in the first system device 100. Similarly, if each drive unit 20 determines that an abnormality has occurred in at least one of the following: the second inverter 201, the second cutoff switch 204, the second stator winding 203, the second control unit 205, the second current sensor 206, and the second rotation angle sensor 207, then it is determined that an abnormality has occurred in the second system device 200. Note that abnormalities in inverters 101 and 201 include, for example, at least one of an open fault or a short fault of the switch SW. An abnormality in the stator windings 103 and 203 includes, for example, at least one of a stator winding open fault and a phase-to-phase short fault.

[0048] If it is determined in step S10 that no abnormality has occurred in either the first system device 100 or the second system device 200, the process proceeds to step S11, where the above-described normal control, such as straight-line driving or turning driving, is performed.

[0049] The following describes the case where it is determined in step S10 that an abnormality has occurred in either the first or second system device 100, 200 constituting the right-side unit 20R. In this case, the process proceeds to step S12, where the right-side unit 20R in which the abnormality occurred sends a command to switch off the circuit breaker switch of the system device in which the abnormality occurred among the first and second system devices 100, 200. For example, as shown in Figure 7, if an abnormality occurs in the first inverter 101 of the first system device 100 of a certain right-side unit 20R, a command is sent to switch off the first circuit breaker switch 104 for three phases. The transmitted command is received by at least one of the first and second control units 105, 205 of the right-side unit 20R in which the abnormality occurred. When at least one of the first and second control units 105, 205 receives the command, it switches off the corresponding circuit breaker switch.

[0050] This prevents regenerative current from flowing to the stator windings, inverter, and smoothing capacitor of the faulty system device, as long as the trip switch does not short-circuit while the automated guided vehicle 10 continues to operate. As a result, it prevents the generation of regenerative torque and prevents adverse effects on the operation control of the automated guided vehicle 10 in fail-safe control.

[0051] Furthermore, even if shutdown control is performed, turning off each switch SW of the inverter when the cutoff switch is ON, a regenerative current flows and a regenerative torque is generated when the back electromotive force generated in the stator winding due to the rotation of the rotor 31 exceeds the terminal voltage of the smoothing capacitor. This regenerative torque adversely affects the driving control of the automated guided vehicle 10.

[0052] In step S13, the right-side unit 20R that has experienced an abnormality sends a shutdown command to turn off the switches SW of the inverters in the first and second system devices 100 and 200 that have experienced the abnormality. The transmitted command is received by at least one of the first and second control units 105 and 205 of the right-side unit 20R that has experienced the abnormality. Upon receiving the command, at least one of the first and second control units 105 and 205 performs shutdown control of the corresponding inverter.

[0053] Furthermore, in step S13, the first and second inverters 101 and 201 of the target left-side unit 20L, which is aligned in the vehicle width direction with the right-side unit 20R where the malfunction occurred (hereinafter referred to as the target left-side unit), are switched to reduce the output torque of the motor 30 to the output torque of the motor 30 of the right-side unit 20R where the malfunction occurred. This allows the automated guided vehicle 10 to continue moving in a straight line while maintaining the stability of its straight-line movement as much as possible.

[0054] Figure 7 shows a case where, in the right-side unit 20R where the abnormality occurred, the switching control of the first inverter 101 is stopped, the output torque corresponding to the first stator winding 103 becomes 0, and the output torque of the motor 30 becomes half of the command torque transmitted from the higher-level ECU 16. In this case, the first and second control units 105 and 205 of the target left-side unit perform switching control of the first and second inverters 101 and 201 of the target left-side unit so as to reduce the output torque of the motor 30 of the target left-side unit to the output torque of the motor 30 of the right-side unit 20R where the abnormality occurred. In the example shown in Figure 7, in the target left-side unit, the output torque corresponding to the first stator winding 103 is reduced from half to one-quarter of the command torque transmitted from the higher-level ECU 16, and the output torque corresponding to the second stator winding 203 is reduced from half to one-quarter of the command torque transmitted from the higher-level ECU 16. However, the reduced output torques corresponding to each stator winding 103 and 203 are not limited to the same torque; they may be different.

[0055] Next, we will explain the case where it is determined in step S10 that an abnormality has occurred in either the first or second system device 100, 200 that constitutes the left unit 20L. In this case, the process proceeds to step S12, where the left unit 20L in which the abnormality occurred sends a command to switch off the circuit breaker switch of the system device in which the abnormality occurred among the first and second system devices 100, 200.

[0056] In step S13, for each left-side unit 20L where an abnormality has occurred, a shutdown command is sent to turn off the switches SW of the inverters of the system device 100, 200 where the abnormality occurred.

[0057] Furthermore, in step S13, in each right-side unit 20R, the right-side unit (hereinafter referred to as the target right-side unit) that is aligned in the vehicle width direction with the left-side unit 20L where the abnormality occurred is controlled by switching the first and second inverters 101 and 201 of the target right-side unit so that the output torque of the motor 30 is reduced to the output torque of the motor 30 of the left-side unit 20L where the abnormality occurred.

[0058] Incidentally, when the automated guided vehicle 10 is to be driven in a turning position, in step S13, the turning control described in the normal control section is performed such that the output torque of the motors of the drive units 20 other than the drive unit where the malfunction occurred is less than or equal to the output torque of the motor 30 of the drive unit where the malfunction occurred.

[0059] According to the embodiment described in detail above, even if an abnormality occurs in either the first system device 100 or the second system device 200 in each drive unit 20 of the automated guided vehicle 10, the automated guided vehicle 10 can continue to operate as much as possible.

[0060] <Modified form of the first embodiment> • Unmanned guided vehicles used in factories are not limited to AGVs; for example, autonomous mobile robots (AMRs) may also be used.

[0061] The higher-level ECU 16 may transmit the commanded rotational speed of the rotor 31 to each right-side unit 20R and each left-side unit 20L instead of the commanded torque.

[0062] <Second Embodiment> The second embodiment will be described below, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, if an abnormality occurs in either the first system device 100 or the second system device 200 in each drive unit 20, the total output torque of the motors 30 of each right-side unit 20R and the total output torque of the motors 30 of each left-side unit 20L are combined to allow the automated guided vehicle 10 to continue moving in a straight line. The processing procedure for the driving control of the automated guided vehicle 10, including the fail-safe control described above, will be explained below using Figure 8. The processing shown in Figure 6 is executed by the higher-level ECU 16.

[0063] In step S20, similar to step S10 in Figure 6, each drive unit 20 determines whether or not an abnormality has occurred in either the first system device 100 or the second system device 200.

[0064] If it is determined in step S20 that no abnormality has occurred in either the first system device 100 or the second system device 200, the process proceeds to step S21, where the normal control described above, such as straight-line driving or turning driving, is performed, similar to step S11 in Figure 6.

[0065] The following describes the case where it is determined in step S20 that an abnormality has occurred in either the first or second system device 100, 200 that constitutes the right-side unit 20R. In this case, the process proceeds to step S22, and, similar to step S12 in Figure 6, a command is sent to the right-side unit 20R where the abnormality occurred among the drive units 20 to switch off the cutoff switch of the system device among the first and second system devices 100, 200 that experienced the abnormality.

[0066] Furthermore, from among the drive units 20 that have not experienced any abnormalities, a drive unit equipped with a system device that reduces the output torque to zero (hereinafter referred to as the zero-torque system device) is selected in step S23, which will be described later. Then, a command is sent to switch off the cutoff switch of the system device that reduces the output torque to zero, among the first and second system devices 100 and 200 of the selected drive unit. This prevents the generation of regenerative torque and prevents adverse effects on the driving control of the automated guided vehicle 10 in fail-safe control.

[0067] In step S23, for each right-side unit 20R where an abnormality has occurred, a shutdown command is sent to turn off the switches SW of the inverters of the system device 100, 200 where the abnormality occurred. Additionally, a shutdown command is sent to turn off the switches SW of the inverters of the zero-torque system device.

[0068] In step S23, the inverters of the first and second system devices 100 and 200 of each drive unit 20 are switched to reduce the total output torque of the motors 30 of each left unit 20L to the total output torque of the motors 30 of the right units 20R that are not experiencing any abnormalities. This is done by switching the inverters of the system devices other than the system device that has been determined to be malfunctioning and the zero-torque system device among the first and second system devices 100 and 200 of each drive unit 20. This allows the automated guided vehicle 10 to continue moving in a straight line while maintaining the stability of its straight-line movement as much as possible.

[0069] Next, we will explain the case where it is determined in step S20 that an abnormality has occurred in either the first or second system device 100, 200 that constitutes the left unit 20L. In this case, the process proceeds to step S22, and, similar to step S12 in Figure 6, a command is sent to the left unit 20L where the abnormality occurred among the drive units 20 to switch off the cutoff switch of the system device among the first and second system devices 100, 200 that experienced the abnormality.

[0070] Furthermore, from among the drive units 20 that have not experienced any abnormalities, a drive unit equipped with a zero-torque system device is selected. Then, a command is sent to switch off the cutoff switch of the system device that reduces the output torque to zero among the first and second system devices 100 and 200 of the selected drive unit.

[0071] In step S23, for each left-side unit 20L where an abnormality has occurred, a shutdown command is sent to turn off the switches SW of the inverters of the system device 100, 200 where the abnormality has occurred. Additionally, a shutdown command is sent to turn off the switches SW of the inverters of the zero-torque system device.

[0072] In step S23, the switching control of the inverters of the first and second system devices 100 and 200 of each drive unit 20 is performed so that the total output torque of the motors 30 of each right-side unit 20R is reduced to the total output torque of the motors 30 of the left-side units 20L that are not experiencing any abnormalities. This control is performed on the system devices other than the system device that has been determined to be experiencing an abnormality and the zero-torque system device.

[0073] Figure 9 shows an example where an abnormality occurs in the first inverter 101 of the first left-hand unit 20L and the second inverter 201 of the third left-hand unit 20L. In this case, the first cutoff switch 104 of the first left-hand unit 20L and the second cutoff switch 204 of the third left-hand unit 20L are switched to the OFF position.

[0074] In the example shown in Figure 9, of the three right-side units 20R, the first and second system devices 100 and 200 of the second right-side unit are selected as zero-torque system devices. As a result, the output torque of the motor 30 of the second right-side unit is set to 0.

[0075] Furthermore, if the total output torque of both the left and right sides is the same, a zero-torque system device is not necessary.

[0076] As described above, the automated guided vehicle 10 can continue to operate according to this embodiment.

[0077] <Third Embodiment> The third embodiment will now be described, focusing on the differences from the above embodiments, with reference to the drawings. In this embodiment, if an abnormality occurs in any of the first or second system devices 100, 200 of each drive unit 20, all of the first and second shut-off switches 104, 204 of each drive unit 20 are switched to the OFF position. The following describes the processing procedure for the driving control of the automated guided vehicle 10, including the fail-safe control described above, using Figure 10. The processing shown in Figure 10 is executed by the higher-level ECU 16.

[0078] In step S30, similar to step S10 in Figure 6, each drive unit 20 determines whether or not an abnormality has occurred in either the first system device 100 or the second system device 200.

[0079] If it is determined in step S30 that no abnormality has occurred in either the first system device 100 or the second system device 200, the process proceeds to step S31, where the normal control described above, such as straight-line driving or turning driving, is performed, similar to step S11 in Figure 6.

[0080] If an abnormality is detected in step S30, the process proceeds to step S32, where a command is sent to switch off all first and second shut-off switches 104 and 204 on each drive unit 20. This switches off all first and second shut-off switches 104 and 204 on each drive unit 20.

[0081] In step S33, a shutdown command is sent to all first and second inverters 101 and 201 of each drive unit 20. This stops the switching control of all first and second inverters 101 and 201 of each drive unit 20.

[0082] If a malfunction occurs in the automated guided vehicle (AGV) 10, an operator may want to move the AGV 10 by hand. In this case, the rotor 31 of the motor 30 rotates, and a back electromotive force is generated in the stator winding 41. According to this embodiment, the generation of regenerative torque caused by the back electromotive force can be prevented. Therefore, the load on the operator to move the AGV 10 can be reduced.

[0083] <Fourth Embodiment> The fourth embodiment will now be described, focusing on the differences from the above embodiments, with reference to the drawings. In this embodiment, as shown in Figure 11, the small mobility device is an electric wheelchair 300 as a small electric vehicle.

[0084] The electric wheelchair 300 comprises a frame 301 and a seat 302 fixed to the frame 301. The seat 302 comprises a seat portion 302a and a backrest portion 302b. The electric wheelchair 300 also comprises armrests 303 and footrests 304 fixed to the frame 301.

[0085] The electric wheelchair 300 is a four-wheeled wheelchair comprising a bracket portion 311 attached to the front of the vehicle frame 301, left and right front wheels 320 attached to the bracket portion 311, and left and right rear wheels 330. In this embodiment, the left and right front wheels 320 serve as steering wheels.

[0086] The electric wheelchair 300 includes a housing 340 fixed to the vehicle frame 301. The housing 340 is located below the seat 302a. The housing 340 houses an electric drive system. The electric drive system includes drive units corresponding to the left and right rear wheels 330, respectively. The drive units have the same configuration as the drive unit 20 described in each of the above embodiments.

[0087] The electric wheelchair 300 is equipped with a control unit 350 operated by the user. The control unit 350 is fixed to the armrest 303. In this embodiment, the control unit 350 is a joystick extending upward. The control unit 350 is a component that instructs the electric wheelchair 300 to move forward, backward, or turn. The electric wheelchair 300's travel speed is, for example, 10 km / h or less.

[0088] The electric drive system of this embodiment has the same configuration as in the embodiments described above and includes a higher-level ECU. For example, when the higher-level ECU determines that the electric wheelchair 300 is instructed to turn based on the input signal from the operation unit 350, it rotates the left and right rear wheels 330 in the same direction and sends a command value for the control amount of the motor 30 (e.g., the rotational speed of the rotor 31) to each drive unit so that the rotational speed of the rear wheel 330 in the instructed turning direction is lower than the rotational speed of the remaining rear wheel 330. For example, if a right turn is instructed, the commanded rotational speed of the right rear wheel 330 is lower than the commanded rotational speed of the left rear wheel 330. The higher-level ECU can also send command values ​​to each drive unit so that the left and right rear wheels 330 rotate in opposite directions. In this case, the electric wheelchair 300 will perform a pivot turn.

[0089] In this embodiment as well, the driving control shown in Figures 6, 8, and 10 can be applied. For example, when the driving control shown in Figure 10 is applied, the process in step S32 is performed, making it easier to manually push the electric wheelchair 300 in the event of a system malfunction. This makes it possible to provide an electric wheelchair 300 that is highly convenient.

[0090] <Fifth Embodiment> The fifth embodiment will now be described, focusing on the differences from the fourth embodiment, with reference to the drawings. As shown in Figure 12, the small mobility device of this embodiment is the Senior Car 400, a small electric vehicle. The users of the Senior Car 400 are, for example, elderly people. The driving speed of the Senior Car 400 is, for example, 10 km / h or less.

[0091] The Senior Car 400 is equipped with a body frame 401. The left and right front wheels 410 are located on the front side of the body frame 401. The left and right rear wheels 420 are located on the rear side of the body frame 401. A handle unit 440, which serves as the steering unit for the Senior Car 400, is located above the front wheels 410. The front wheels 410 are attached to the body frame 401 via axles and suspensions 411 (not shown). The rear wheels 420 are attached to the body frame 401 via axles and suspensions 421 (not shown). In this embodiment, the left and right front wheels 410 are steering wheels, and the left and right rear wheels 420 are drive wheels that are rotationally driven by a drive unit described later.

[0092] The Senior Car 400 is equipped with a seat 430, which comprises a seat portion 430a and a backrest portion 430b.

[0093] The Senior Car 4100 is equipped with a drive unit fixed to the vehicle frame 401.

[0094] The Senior Car 400 is equipped with an electric drive system. The electric drive system includes drive units corresponding to the left and right front wheels 410 and the left and right rear wheels 420, respectively. The drive units have the same configuration as the drive unit 20 described in each of the above embodiments. Note that drive units may be provided only for the left and right front wheels 410, or only for the left and right rear wheels 420.

[0095] The electric drive system of this embodiment has the same configuration as in the above embodiments and includes a higher-level ECU. The higher-level ECU transmits command values ​​to each drive unit, similar to the third embodiment. As a result, the senior car 400 can perform straight-line driving, turning, and other maneuvers, similar to the third embodiment.

[0096] In this embodiment as well, the driving control shown in Figures 6, 8, and 10 can be applied. For example, when the driving control shown in Figure 10 is applied, the process in step S32 is performed, making it easier to push the Senior Car 400 by hand in the event of a malfunction in the power system. This makes it possible to provide a Senior Car 400 that is highly convenient.

[0097] <Other Embodiments> Furthermore, each of the above embodiments may be implemented with the following modifications.

[0098] The electrical configuration of the drive unit 20 is not limited to the configuration shown in Figure 5; for example, it may be the configuration shown in Figure 13. In the configuration shown in Figure 13, the control unit 115 is common to both the first system device 100 and the second system device 200, and the rotation angle sensor 117 for detecting the rotation angle position (electrical angle) of the rotor 31 is also common. In addition, the power supply for the first inverter 101 and the second inverter 201 is the energy storage unit 15, and the power supply is common to both.

[0099] The drive unit 20 does not necessarily need to be equipped with a higher-level ECU 16. In this case, for example, it is sufficient if one of the first control unit 105 and the second control unit 205 functions as a master and the other functions as a slave.

[0100] Each drive unit 20 may be equipped with three or more system devices.

[0101] In the first to third embodiments, the number of drive wheels of the automated guided vehicle is not limited to six.

[0102] The motor is not limited to an inner rotor type; an outer rotor type is also acceptable.

[0103] • The small mobility device is not limited to those exemplified in the above embodiments, but may also be, for example, an electric bicycle or an electric kick scooter. Furthermore, the small mobility device may be equipped with crawlers suitable for off-road travel on its drive wheels.

[0104] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. [Explanation of Symbols]

[0105] 10...Automated Guided Vehicle, 12...Drive Wheel, 20...Drive Unit, 30...Motor, 31...Rotor, 32...Shaft, 50...Housing, 100, 200...First and Second System Devices, 101, 201...First and Second Inverters, 103, 203...First and Second Stator Windings, 105, 205...First and Second Control Units.

Claims

1. In an electric drive system for moving a vehicle (10, 300, 400), The aforementioned vehicle is equipped with a pair of left and right drive wheels (12R, 12L) arranged in the width direction of the vehicle, Each of the aforementioned drive wheels is individually provided with a drive unit (20R, 20L) that rotates the drive wheel, Each of the aforementioned drive units is: Multiple system devices (100, 200), A motor (30) is configured and includes a rotor (31) common to each of the aforementioned system devices, A housing (50) that accommodates each of the aforementioned system devices and the rotor, It has, Each of the aforementioned system devices, The stator windings (41, 103, 203) that constitute the motor, An inverter (101, 201) electrically connected to the stator winding, Rotation angle sensors (107, 207) for detecting the rotational angle position of the rotor, A control unit (105, 205) that rotates the rotor and thereby rotates the drive wheel, performs switching control of the inverter based on the detected value of the rotation angle sensor it possesses, It has, In each of the aforementioned drive units, the control units of each of the aforementioned system devices are configured to communicate with each other within the housing space enclosed by the housing. If an abnormality occurs in any of the system devices in the right-side unit (20R), which is the drive unit that rotates the right-side drive wheel (12R), the control unit will perform switching control of the inverter in the system devices of the right-side unit that are not experiencing any abnormalities, and the control unit will also perform switching control of the inverter in the system devices of the left-side unit (20L), which is the drive unit that rotates the left-side drive wheel (12L), thereby allowing the vehicle to continue running. An electric drive system that, in the event of an abnormality occurring in any of the system devices in the left unit, allows the vehicle to continue running by having the control unit perform switching control of the inverter in the system device in the left unit that is not experiencing an abnormality, and by having the control unit perform switching control of the inverter in the system device in the right unit.

2. Each of the system devices has a current sensor (106, 206) that detects the current flowing through the stator winding it has, The electric drive device according to claim 1, wherein in each of the aforementioned system devices, the detected value of the current sensor it possesses is further used for switching control of the inverter it possesses.

3. If an abnormality occurs in any of the system devices in the right-side unit, the control unit will reduce the output torque of the motor in the left-side unit to the output torque of the motor in the right-side unit to allow the vehicle to continue running, by performing switching control of the inverter in the system devices of the right-side unit that are not experiencing any abnormalities, and by performing switching control of the inverter in the system devices of the left-side unit. The electric drive device according to claim 1 or 2, wherein if an abnormality occurs in any of the system devices in the left unit, the control unit performs switching control of the inverter in the system devices of the left unit that are not experiencing an abnormality, and the control unit also performs switching control of the inverter in the system devices of the right unit, so as to allow the vehicle to continue running, if an abnormality occurs in any of the system devices in the left unit, the output torque of the motor of the right unit is reduced to the output torque of the motor of the left unit.

4. The vehicle (10) is equipped with multiple sets of the left and right pairs of drive wheels arranged in the width direction of the vehicle, If an abnormality occurs in any of the system devices in each of the right-side units, the control unit will perform switching control of the inverter in the system device in each of the right-side units that is not experiencing an abnormality, and the control unit will also perform switching control of the inverter in each of the system devices in each of the left-side units, thereby allowing the vehicle to continue running. The electric drive device according to claim 1 or 2, wherein if an abnormality occurs in any of the system devices in each of the left units, the control unit performs switching control of the inverter in the system device in each of the left units that is not experiencing an abnormality, and the control unit performs switching control of the inverter in each of the system devices in each of the right units, thereby allowing the vehicle to continue running.

5. If an abnormality occurs in any of the system devices in each of the right-side units, the control unit will reduce the output torque of the motor in the left-side unit that is aligned in the vehicle width direction with the right-side unit having the abnormal system device to the output torque of the motor in the right-side unit having the abnormal system device, thereby allowing the vehicle to continue running. This will be done by the control unit performing switching control of the inverter in the system devices of each right-side unit that are not experiencing abnormalities, and by the control unit performing switching control of the inverter in the system devices of each left-side unit. The electric drive device according to claim 4, wherein if an abnormality occurs in any of the system devices in each of the left units, the control unit performs switching control of the inverter in the system devices of each left unit that are not experiencing an abnormality, and the control unit also performs switching control of the inverter in the system devices of each right unit, so as to reduce the output torque of the motor of the right unit that is aligned in the vehicle width direction with the left unit that has the abnormal system device to the output torque of the motor of the left unit that has the abnormal system device, in order to continue driving the vehicle.

6. If an abnormality occurs in any of the system devices in each of the right-side units, the control unit will perform switching control of the inverter in at least one system device in each of the right-side units that is not experiencing an abnormality, so that the total output torque of the motors in each of the left-side units is reduced to the total output torque of the motors in each of the right-side units, and the control unit will perform switching control of the inverter in at least one system device in each of the left-side units. The electric drive device according to claim 4, wherein if an abnormality occurs in any of the system devices in each of the left units, the control unit performs switching control of the inverter in at least one system device in each of the left units where no abnormality has occurred, and the control unit also performs switching control of the inverter in at least one of the system devices in each of the right units, so as to reduce the total output torque of the motors in each of the right units to the total output torque of the motors in each of the left units in order to continue driving the vehicle.

7. Each pair of the drive wheels, arranged in the width direction of the vehicle, is provided in the length direction of the vehicle. If an abnormality occurs in any of the system devices in each of the right-side units, the control unit will perform switching control of the inverter in at least one system device in each of the right-side units that is not experiencing an abnormality, so as to continue the vehicle's operation by combining the total output torque of the motors in each of the left-side units with the total output torque of the motors in each of the right-side units, and the control unit will also perform switching control of the inverter in at least one system device in each of the left-side units. If an abnormality occurs in any of the system devices in each of the left units, the control unit performs switching control of the inverter in at least one system device in each of the left units where no abnormality has occurred, so as to continue driving the vehicle by combining the total output torque of the motors in each of the right units with the total output torque of the motors in each of the left units, and the control unit also performs switching control of the inverter in at least one of the system devices in each of the right units, according to claim 4.

8. The aforementioned vehicle is Automated guided vehicles (10) used in factories, A small electric vehicle (300, 400) is provided with front wheels (320, 410), rear wheels (330, 420), and a user seat (302, 430), wherein at least one of the front wheels and the rear wheels (330, 410, 420) is the drive wheel. Each of the aforementioned drive units has a circuit breaker switch (104, 204) that, when turned on, electrically connects the stator winding and the inverter, and when turned off, electrically disconnects the stator winding and the inverter. The electric drive device according to claim 1 or 2, wherein if an abnormality occurs in any of the system devices in each of the drive units, the cutoff switch of the system device in which the abnormality occurred is turned off.

9. The aforementioned vehicle is Automated guided vehicles (10) used in factories or A small electric vehicle (300, 400) is provided with front wheels (320, 410), rear wheels (330, 420), and a user seat (302, 430), wherein at least one of the front wheels and the rear wheels (330, 410, 420) is the drive wheel. Each of the aforementioned drive units has a circuit breaker switch (104, 204) that, when turned on, electrically connects the stator winding and the inverter, and when turned off, electrically disconnects the stator winding and the inverter. The electric drive device according to claim 1 or 2, wherein the control unit turns off the cutoff switches of all the system devices constituting each drive unit if an abnormality occurs in any of the system devices in each drive unit.

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