Method and system for absorbing electrical energy from motor

Abstract

A method and system for absorbing electrical energy from a motor is disclosed. The method and system transfers the generated electrical energy from the motor to the absorber.

Description

Technical Field

[0001] The present invention relates to methods and systems for absorbing energy from motors, such as those used in load handling equipment. Background Art

[0002] Some industrial and commercial activities require systems that can store and access a large number of different products. WO 2015 / 185628A describes a storage and fulfillment system in which stacks of storage containers are arranged in a grid storage structure. The containers are accessed from above by load handling equipment that runs on rails or tracks atop the grid storage structure. The load handling equipment is further described in WO 2015 / 019055A1.

[0003] In storage and fulfillment systems, it is important that load handling equipment transfer the energy generated by motors to prevent components from operating beyond their rated values. The present invention is designed in this context. Summary of the Invention

[0004] In a first aspect, there is provided a system for consuming energy generated by a motor, the system comprising: First Motor; a second motor; and A controller configured to: driving a first motor; detecting electrical energy generated by the first motor; and The generated electrical energy is transferred to the second motor. This means the second motor can absorb the electrical energy generated by the first motor and prevent damage to the system. The second motor also acts as a heat sink.

[0005] The controller can be configured to control the absorption of the generated electrical energy by the second motor using field-oriented control or vector control. This means that the absorption of the generated electrical energy can be precisely controlled.

[0006] The controller can be configured to absorb all generated electrical energy on the direct axis of the second motor using field oriented control or vector control. This means that the second motor does not generate torque when absorbing the electrical energy generated by the first motor.

[0007] The system may include a bus configured to deliver power to the first motor and / or the second motor, wherein the controller is configured to monitor the voltage on the bus to detect energy generated by the first motor. This means that any potential damage to the system can be proactively identified.

[0008] The controller can be configured to transfer the generated power to the second motor when the voltage on the bus reaches a threshold. This means that any damage to the system and its circuits can be avoided.

[0009] The controller can be configured to divert the generated power until the voltage on the bus is below a threshold, or until the current limit of the second motor is reached, or until the temperature limit of the second motor is reached. This means that the system operates within safe limits.

[0010] The set point for the direct-axis current can be increased until the voltage on the bus falls below a threshold, or until the current limit of the second motor is reached, or until the temperature limit of the second motor is reached. This means that the power generated by the first motor is always transferred to the second motor, and the system can operate normally in other respects.

[0011] The system may further comprise a third motor, wherein the controller is configured to transfer part of the generated electrical energy to the third motor. This means that the system can utilize additional absorption capacity when necessary.

[0012] The system may comprise a power source, such as a battery, wherein the controller is configured to transfer part of the generated electrical energy to the power source. This means that the battery can be recharged.

[0013] The second motor or the third motor may include a multi-phase motor, such as a permanent magnet synchronous motor (PMSM). The low phase resistance of the PMSM helps absorb the electrical energy generated by the first motor.

[0014] The load handling equipment may include a system, wherein the load handling equipment may be configured to lift and move storage containers stacked in a grid frame structure, the grid frame structure comprising: A first set of parallel tracks or rails and a second set of parallel tracks or rails extending in a substantially horizontal plane substantially perpendicular to the first set of tracks or rails to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be vertically stacked between the uprights and vertically guided by the uprights through the plurality of grid spaces, the load handling apparatus may comprise: a body or frame mounted on a first set of wheels configured to engage the first set of parallel tracks and a second set of wheels configured to engage the second set of parallel tracks; and a drive assembly comprising a first motor or a second motor, wherein the first motor or the second motor is configured to drive the first set of wheels or the second set of wheels to move the load handling device along the first set of parallel tracks or the second set of parallel tracks, respectively; and A container lift assembly includes the other of a first motor or a second motor, wherein the other of the first motor or the second motor is configured to raise or lower the gripping device in a vertical direction. This means that each of the first function and the second function of the load handling device can provide suction when performing the second function and the first function, respectively.

[0015] The load handling equipment may include a system, wherein the load handling equipment may be configured to lift and move storage containers stacked in a grid frame structure, the grid frame structure comprising: A first set of parallel tracks or rails and a second set of parallel tracks or rails extending in a substantially horizontal plane substantially perpendicular to the first set of tracks or rails to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be vertically stacked between the uprights and vertically guided by the uprights through the plurality of grid spaces, the load handling apparatus may comprise: a body or frame mounted on a first set of wheels configured to engage the first set of parallel tracks and a second set of wheels configured to engage the second set of parallel tracks; and a drive assembly comprising a first motor or a second motor, wherein the first motor or the second motor is configured to drive the first set of wheels or the second set of wheels to move the load handling device along the first set of parallel tracks or the second set of parallel tracks, respectively; and A change of direction assembly includes the other of the first motor or the second motor, wherein the other of the first motor or the second motor is configured to raise or lower the first set of wheels relative to the body or frame and / or lower or raise the second set of wheels relative to the body or frame to engage and disengage the wheels from the parallel tracks. This means that each of the first and second functions of the load handling apparatus can provide absorption when performing the second and first functions, respectively.

[0016] The load handling equipment may include a system, wherein the load handling equipment may be configured to lift and move storage containers stacked in a grid frame structure, the grid frame structure comprising: A first set of parallel tracks or rails and a second set of parallel tracks or rails extending in a substantially horizontal plane substantially perpendicular to the first set of tracks or rails to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be vertically stacked between the uprights and vertically guided by the uprights through the plurality of grid spaces, the load handling apparatus may comprise: a body or frame mounted on a first set of wheels configured to engage the first set of parallel tracks and a second set of wheels configured to engage the second set of parallel tracks; and a container lifting assembly comprising a first motor or a second motor, wherein the first motor or the second motor is configured to raise or lower the clamping device in a vertical direction; and A change of direction assembly includes the other of the first motor or the second motor, wherein the other of the first motor or the second motor is configured to raise or lower the first set of wheels relative to the body or frame and / or lower or raise the second set of wheels relative to the body or frame to engage and disengage the wheels from the parallel tracks. This means that each of the first and second functions of the load handling apparatus can provide absorption when performing the second and first functions, respectively.

[0017] The load handling equipment may include a system, wherein the load handling equipment may be configured to lift and move storage containers stacked in a grid frame structure, the grid frame structure comprising: A first set of parallel tracks or rails and a second set of parallel tracks or rails extending in a substantially horizontal plane substantially perpendicular to the first set of tracks or rails to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be vertically stacked between the uprights and vertically guided by the uprights through the plurality of grid spaces, the load handling apparatus may comprise: a body or frame mounted on a first set of wheels configured to engage the first set of parallel tracks and a second set of wheels configured to engage the second set of parallel tracks; and a drive assembly comprising a first motor and a second motor, wherein the first motor is configured to drive a first set of wheels to move the load handling apparatus along a first set of parallel rails, and wherein the second motor is configured to drive a second set of wheels to move the load handling apparatus along a second set of parallel rails; and optionally, A change of direction assembly is configured to raise or lower the first set of wheels relative to the body or frame and / or lower or raise the second set of wheels relative to the body or frame to engage and disengage the wheels from the parallel tracks. This means that each of the first and second functions of the load handling apparatus (in this case, travel in the X and Y directions) can provide accommodation when performing the second and first functions, respectively.

[0018] In a second aspect, there is provided a method for transferring electrical energy using the system of any of the above aspects, wherein the method comprises: Use the controller to: driving a first motor; detecting electrical energy generated by the first motor; and The generated electrical energy is transferred to the second motor.

[0019] In a third aspect, there is provided a computer program comprising instructions which, when executed by a computer, cause the computer to perform the method of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is described with reference to one or more exemplary embodiments depicted in the accompanying drawings, in which: Figure 1 shows a storage structure and container; FIG2 shows the rails on top of the storage structure shown in FIG1 ; FIG3 shows a load handling device on top of the storage structure shown in FIG1 ; FIG4 shows a single load handling device with the container lift in a lowered configuration; 5A and 5B illustrate cross-sectional views of a single load handling apparatus with a container lift in a raised and lowered configuration; Figure 6 is a schematic diagram of a load handling device having a direction changing assembly; Figure 7 An exemplary container lift assembly is shown; Figure 8 is a schematic diagram of a load handling apparatus according to the present invention; Figure 9 A method according to the present invention is shown; and Figure 10 A system according to the invention is shown. DETAILED DESCRIPTION

[0021] Online retailers, such as online grocers and supermarkets, that sell multiple product lines require systems capable of storing tens or hundreds of thousands of different product lines. In such cases, using single-product palletizing may be impractical, as it would require a very large floor space to accommodate all the required pallets. Furthermore, only a small number of items, such as perishables or infrequently ordered goods, may need to be stored, making single-product palletizing an inefficient solution.

[0022] International patent application WO 98 / 049075 A (Autostore), the content of which is incorporated herein by reference, describes a system in which stacks of multi-product containers are arranged within a frame structure.

[0023] PCT Publication No. WO2015 / 185628A (Ocado) describes a further known storage and fulfillment system in which stacks of containers are arranged within a grid frame structure. The containers are accessed by one or more load handling devices (also known as "robots") that operate on tracks atop the grid frame structure. This type of system is schematically illustrated in Figures 1 to 3 of the accompanying drawings.

[0024] As shown in Figures 1 and 2, stackable containers 10, also known as "boxes," are stacked on top of each other to form stacks 12. The stacks 12 are arranged in a grid frame structure 14, for example in a warehousing or manufacturing environment. The grid frame structure 14 is composed of a plurality of storage columns or grid columns. Each grid in the grid frame structure has at least one grid column to store stacks of containers. Figure 1 is a schematic perspective view of the grid frame structure 14, and Figure 2 is a schematic top view of the stack 12 of boxes 10 arranged in the frame structure 14. Each box 10 typically holds a plurality of product items (not shown). The product items within the box 10 can be the same or different product types, depending on the application.

[0025] The grid frame structure 14 includes a plurality of upright members 16 supporting horizontal members 18, 20. A first set of parallel horizontal grid members 18 are arranged perpendicular to a second set of parallel horizontal members 20 in a grid pattern to form a horizontal grid structure 15 supported by the upright members 16. The members 16, 18, 20 are typically made of metal. The boxes 10 are stacked between the members 16, 18, 20 of the grid frame structure 14 such that the grid frame structure 14 prevents horizontal movement of the stack 12 of boxes 10 and guides vertical movement of the boxes 10.

[0026] The top layer of the grid frame structure 14 includes a grid or grid structure 15 that includes rails 22 arranged in a grid pattern across the top of the stack 12. Referring to Figure 3, the rails or tracks 22 guide a plurality of load handling devices 30. A first set 22a of parallel rails 22 guides movement of the robotic load handling devices 30 across the top of the grid frame structure 14 in a first direction (e.g., the X direction). A second set 22b of parallel rails 22, arranged perpendicular to the first set 22a, guides movement of the load handling devices 30 in a second direction (e.g., the Y direction) that is perpendicular to the first set 22a. In this way, the rails 22 allow the robotic load handling devices 30 to move laterally in two dimensions within a horizontal XY plane. The load handling devices 30 can be moved to a position above any stack 12.

[0027] PCT Patent Publication No. WO2015 / 019055 (Ocado), incorporated herein by reference, describes a known form of load handling apparatus 30 as shown in Figures 4, 5A, and 5B, wherein each load handling apparatus 30 covers a single grid space 17 of the grid frame structure 14. This arrangement allows for a higher density of load handlers, and thus higher throughput for a given size system.

[0028] The load handling equipment 30 includes a carrier 32 that is arranged to travel on the rails 22 of the frame structure 14. A first set of wheels 34, consisting of a pair of wheels 34 at the front of the carrier 32 and a pair of wheels 34 at the rear of the carrier 32, is arranged to engage two adjacent rails of the first set 22a of rails 22. Similarly, a second set of wheels 36, consisting of a pair of wheels 36 on each side of the carrier 32, is arranged to engage two adjacent rails of the second set 22b of rails 22. Each set of wheels 34, 36 can be turned by a direction-changing assembly (an embodiment of which is shown in FIG. Figure 6 The carrier 32 is raised and lowered so that either the first set of wheels 34 or the second set of wheels 36 is engaged with the respective set of rails 22a, 22b at any one time. For example, when the first set of wheels 34 is engaged with the first set of rails 22a and the second set of wheels 36 is lifted off the rails 22, the first set of wheels 34 can be driven by a drive mechanism housed in the carrier 32 to move the load handling device 30 in the X direction. To achieve movement in the Y direction, the first set of wheels 34 is lifted off the rails 22, while the second set of wheels 36 is lowered into engagement with the second set of rails 22b. The drive assembly can then be used to drive the second set of wheels 36 to move the load handling device 30 in the Y direction.

[0029] The loading handling equipment 30 is equipped with a container lifting device or container lifting assembly (an embodiment of which is shown in FIG. Figure 71 and 2 ). The lifting device includes a winch tether or cable 38 wound on a reel or spool and a gripper device 39. The lifting device shown in FIG4 includes a set of four lifting tethers 38 extending in a vertical direction. The tethers 38 are connected at or near the four corners of a gripper device 39 (e.g., a lifting frame) for releasable attachment to the storage container 10. For example, a separate tether 38 is arranged at or near each of the four corners of the lifting frame. The gripper device 39 is configured to releasably grip the top of the storage container 10 to lift the storage container from a stack of containers in a storage system of the type shown in FIG1 and FIG2 . For example, the lifting frame 39 may include pins (not shown) that engage corresponding holes (not shown) in a rim, and sliding clamps (not shown) that engage the rim to grip the box 10, where the rim forms the top surface of the box 10. The clamps are driven into engagement with the box 10 by a suitable drive mechanism housed within the lift frame 39 and powered and controlled by signals transmitted via the cable 38 itself or a separate control cable (not shown).

[0030] In order to remove the box 10 from the top of the stack 12, the loading handling device 30 is first moved in the X and Y directions to position the clamping device 39 above the stack 12. As shown in Figures 4 and 5B, the clamping device 39 is then lowered vertically in the Z direction to engage with the box 10 at the top of the stack 12. The clamping device 39 clamps the box 10 and is then pulled upward by the cable 38 together with the attached box 10. When it vertically travels to the top, the box 10 is held above the rail 22 and is accommodated in the carrier body 32. In this way, the loading handling device 30 can be moved to different positions in the XY plane while carrying the box 10 to transport the box 10 to another location. Once the target location is reached (such as another stack 12, an access point to the storage system, or a conveyor belt), the box or container 10 can be lowered from the container receiving portion and released from the clamping device 39. The cable 38 is long enough to allow the load handling device 30 to retrieve and place a box from any level of the stack 12 (eg, including floor level).

[0031] As shown in FIG3 , a plurality of identical load handling devices 30 are provided so that each load handling device 30 can operate simultaneously to increase the throughput of the system. The system illustrated in FIG3 may include specific locations (referred to as ports) at which boxes 10 can be transported into or out of the system. A separate conveyor system (not shown) is associated with each port, so that boxes 10 transported to a port by a load handling device 30 can be transported via the conveyor system to another location, such as a picking station (not shown). Similarly, boxes 10 can be moved from an external location to a port via a conveyor system, such as a box filling station (not shown), and then transported by the load handling device 30 to a stack 12 to replenish inventory in the system.

[0032] Each load handling device 30 can lift and move one box 10 at a time. The load handling device 30 has a container-receiving cavity or recess 40 in its lower portion. As shown in Figures 5A and 5B, the recess 40 is sized to accommodate the container 10 when it is lifted by the lifting mechanism. While in the recess, the container 10 is lifted off the underlying rails 22, allowing the carrier 32 to be moved laterally to different grid locations.

[0033] If a box 10b not at the top of a stack 12 (the "target box") needs to be retrieved, the box 10a above it (the "non-target box") must first be moved to allow access to the target box 10b. This is accomplished through an operation hereinafter referred to as "digging." Referring to FIG. 3 , during the digging operation, one of the load handling devices 30 sequentially lifts each non-target box 10a from the stack 12 containing the target box 10b and places it in an empty location within another stack 12. The target box 10b can then be accessed by the load handling device 30 and moved to a port for further transport.

[0034] Each of the provided load handling devices 30 operates remotely under the control of a central computer. Each individual bin 10 in the system is also tracked so that the appropriate bin 10 can be retrieved, transported, and replaced as needed. For example, during an excavation operation, the location of each non-target bin is recorded so that the non-target bin 10a can be tracked.

[0035] Wireless communications and networking can be used to provide a communication infrastructure from a main controller to one or more load handling devices operating on the grid structure (e.g., via one or more base stations). In response to instructions received from the main controller, controllers within the load handling devices are configured to control various drive mechanisms to control the movement of the load handling devices. For example, the load handling device can be instructed to remove a container from a target storage column at a specific location on the grid structure. Instructions can include various movements within the XY plane of the grid structure 15. As previously described, once at the target storage column, a lifting mechanism can be operated to grip and lift the storage container 10. Once the container 10 is received in the container receiving space 40 of the load handling device 30, the container 10 is then transported to another location on the grid structure 15, such as a "drop-off port." At the drop-off port, the container 10 is lowered to a suitable picking station to allow any items to be removed from the storage container. Movement of the load handling device 30 on the grid structure 15 can also include being instructed to move the load handling device 30 to a charging station, typically located on the periphery of the grid structure 15.

[0036] In order to maneuver the load handling devices 30 on the grid structure 15, each load handling device 30 is equipped with a motor for driving wheels 34, 36. The wheels 34, 36 can be driven by one or more belts connected to the wheels, or individually by motors integrated into the wheels. For single-unit load handling devices (where the footprint of the load handling device 30 occupies a single grid cell 17), the motors for driving the wheels can be integrated into the wheels due to the limited space available within the vehicle body. For example, the wheels of the single-unit load handling devices are driven by respective wheel hub motors. Each wheel hub motor comprises an outer rotor with a plurality of permanent magnets, which is arranged to rotate around a hub comprising coils, wherein the coils form an inner stator.

[0037] The system described with reference to Figures 1 to 5 has many advantages and is suitable for a wide range of storage and retrieval operations. Specifically, it allows for high-density storage of products and can provide a very economical way to store a large number of different items in bins 10 while allowing all bins 10 to be accessed in a relatively economical manner when picking is required.

[0038] Figure 6 An exemplary change of direction assembly is shown in FIG (further described in PCT Publication No. WO2021175922A1 (Ocado) and PCT Application No. PCT / EP2022 / 073670 (Ocado)). Figure 6 As can be seen in FIG, a first pair of direction-changing mechanisms 610 are positioned on opposing faces within the body or frame 602 of the load handling apparatus for controlling the position of the first set of wheels 36, and a second pair of direction-changing mechanisms 610 are positioned on orthogonally opposing faces of the body or frame of the load handling apparatus for controlling the position of the second set of wheels 38. Thus, each face of the load handling apparatus includes a direction-changing mechanism 610. The pairs of direction-changing mechanisms 610 are coupled via a drive belt 608 that substantially encircles the frame 602 of the load handling apparatus and is mechanically coupled to the direction-changing mechanisms.

[0039] The output of the direction-changing mechanism is transferred to the wheels 34, 36 via a chassis that converts the horizontal movement of the direction-changing mechanism into vertical movement of the wheels. In some arrangements, the direction-changing mechanism can be attached via guide bearings to a rod structure that extends along the face of the load handling device 30 between each horizontal edge of the load handling device 30. The rod structure can then be attached to a corner piece at a first end and a second end.

[0040] The wheel sets 34, 36 can be moved simultaneously, for example, by a motor (not shown) and drive belt 608, to engage the X-direction wheel set and the Y-direction wheel set with the rails of the storage system grid. Activating the motor in a clockwise direction can move the wheel mounts on a face upward, raising the wheels on that face and lowering the wheels on a face perpendicular to the first face, or vice versa.

[0041] Figure 7 An exemplary container lifting assembly is shown in FIG (further described in PCT application no. PCT / EP2022 / 081364 (Ocado)). Figure 7 In FIG, the lifting assembly 700 has four reels 701, 702, 703, and 704 for winding and unwinding respective tethers 38. Reels 701 and 702 are on a drive shaft 705, while reels 703 and 704 are on a drive shaft 706. When driven by a motor, drive shafts 705 and 706 are configured to rotate in opposite directions. By rotating drive shafts 705 and 706 in opposite directions, respective tethers 38 can be positioned at or near a corner of the lifting assembly. Specifically, as Figure 7 As shown, the point at which each tether is wound onto or unwound from the reel is located at or near a respective corner of the lifting assembly. This enables the tether to be connected to the container gripping device 39 at the respective corner of the gripping assembly, thereby increasing stability when raising and lowering the container gripping device 39. Figure 7 An example of how drive shafts 705 and 706 can rotate in opposite directions is shown. Drive shafts 705 and 706 are connected to pulleys 710 and 711, respectively. Pulley 707 (or 709) is connected to the shaft / rotor / rotor of the motor ( Figure 7 Drive belt 708 transmits torque to pulleys 709, 710, and 711 in a manner that ensures that reels 701 and 702, and reels 703 and 704 rotate in opposite directions. Specifically, pulleys 707 and 709 are arranged around pulley 711 to achieve their rotation opposite to that of pulley 710.

[0042] It should now be understood that the load handling apparatus 30 has three systems (each of which may utilize at least one motor): a direction-changing assembly, a drive assembly, and a container lifting assembly. Each motor tends to switch to a power-generating mode when undergoing rapid deceleration. That is, the motor generates more power than it consumes. Rapid motor deceleration may occur when the container gripping assembly approaches a container in the grid assembly, when the load handling apparatus reaches the desired position of the grid frame structure 14, or when the direction-changing assembly completes a directional switch. The generated electrical energy may cause the power supply to operate beyond its rating or capacity, thereby damaging the power supply (i.e., battery) and any connected circuitry. While it is possible to feed the generated electrical energy back into the power supply, this is limited by the power supply's charge level. If the power supply (battery) is already at or near full charge, the power supply cannot absorb the generated electrical energy, and attempting to do so may damage the power supply.

[0043] It is known to use braking resistors to absorb and dissipate the generated electrical energy. Once the generated electrical energy is detected, the braking resistor is connected to a power circuit (for example, using a metal-oxide-semiconductor field-effect transistor (MOSFET) switch) to absorb and dissipate the generated energy. However, in certain situations, such as load handling equipment, the use of braking resistors can be problematic because they require considerable space to effectively absorb and dissipate the generated electrical energy. Given the potentially significant amount of electrical energy generated in load handling equipment, the size of the braking resistor increases accordingly. Furthermore, consideration must be given to the circuitry controlling the operation of the braking resistor. Therefore, it would be desirable to absorb the generated electrical energy without the use of a braking resistor. It should be understood that this problem is common in all systems that must absorb the electrical energy generated by motors. The above description is merely an example of the use of motors in load handling equipment. It would be desirable to be able to absorb the electrical energy generated by motors in any system while avoiding the aforementioned issues.

[0044] Figure 8 A schematic diagram 800 of a load handling device 30 according to the present invention is shown. The dashed lines show that the carrier body 32 of the load handling device travels on the grid 22a / 22b via wheels 34 / 36. The container lifting assembly (e.g., FIG. 4, FIG. 5A, FIG. 5B and FIG. 5C) is shown. Figure 7The container lift assembly (shown in FIG. 1 ) has a motor 810 that can be driven to raise and / or lower the container gripper assembly 39. The direction change assembly has a motor 820 that can be driven to engage either the first set of wheels 34 or the second set of wheels 36 with the respective set of rails 22a, 22b at any one time. The X / Y drive assembly has a motor 830 that can be driven to move the load handling device 30 in the X and / or Y directions. A processor or controller 840 can receive data from each of the container lift assembly motor 810, the direction change motor 820, and the X and / or Y drive assembly motor(s) 830, and can transmit data to each of the container lift assembly motor 810, the direction change motor 820, and the X and / or Y drive assembly motor(s) 830. Processor / controller 840 may also communicate with power supply 860, which is used to power each of container lift assembly motor 810, direction change motor 820, and X and / or Y drive assembly motor(s) 830. Any data used by processor / controller 840 may be stored in storage space 850. The data in storage space 850 may be periodically transmitted via one or more networks (e.g., a base station) for further processing.

[0045] Figure 9 The steps of method 900 are shown for use in a system including two motors (e.g., motors used in load handling equipment). It should be understood that a processor / controller (e.g., Figure 8 The processor / controller 840 of the loading processing device) to execute Figure 9 In step 910, a first motor (which can be one of the container lift assembly motor 810, the direction change motor 820, or the X and / or Y drive assembly motors 830) is driven. A processor / controller (e.g., processor / controller 840) controls the speed of the first motor—and therefore, the acceleration and deceleration of the first motor. When the first motor undergoes rapid deceleration, it may generate more power than it consumes.

[0046] In step 920, the electrical energy generated by the first motor is detected. This can be accomplished by monitoring the voltage on a bus connecting a power supply to the first motor. The energy generated by the first motor will cause the voltage on the bus to increase, which can be detected using appropriate circuitry. The bus can be monitored to detect a threshold voltage indicative of the electrical energy generated. For example, the threshold can be set to the rated value of the power supply powering the first motor. A voltage on the bus exceeding the threshold indicates the electrical energy generated. It will be appreciated that the threshold can be set based on the system in which the power supply, the first motor, and the second motor are used.

[0047] In step 930, once the threshold voltage is detected, the generated electrical energy is transferred to the second motor (which can be one of the container lift assembly motor 810, the direction change motor 820, or the X and / or Y drive assembly motors 830 that is not driven as the first motor). This means that the generated electrical energy, which could damage the power supply, is transferred to the second motor. In this step, the second motor is not driven. It has been found that the armature winding of the second motor can act as an effective current sink and heat sink for the electrical energy generated by the first motor. Specifically, motors tend to have low electrical resistance (or low phase resistance) and relatively high thermal capacity. Any damage to the power supply and / or system can be avoided. In addition, part of the electrical energy generated by the first motor can be directed to recharge the power supply.

[0048] The generated electrical energy can be diverted until one of the following conditions is met: 1. the bus voltage drops below a threshold voltage; 2. the second motor's current limit is reached; and 3. the second motor's temperature limit is reached. For condition 1, a proportional-integral (PI) controller can be used to maintain the bus voltage at its threshold voltage. The input to the PI controller can be the difference between the measured bus voltage and the threshold voltage, while the output of the PI controller is the current delivered to the second motor. Any suitable sensor can be used to determine whether condition 2 or condition 3 has been met. When condition 2 or condition 3 is met, the generated electrical energy can be directed to recharge the power source or to another motor in the system. However, if the generated electrical energy cannot be diverted to the power source or another motor due to power source saturation or unavailability, the braking performance of the first motor can be adjusted. In other words, the deceleration of the first motor (which results in the generation of electrical energy) can be mitigated.

[0049] In one embodiment, the controller employs field-oriented control (FOC) or vector control for the second motor, which can be a multiphase motor such as a permanent magnet synchronous motor (PMSM). FOC or vector control controls the motor using two currents, which define orthogonal d-axis (direct) and q-axis (quadrature) components, respectively. The d-axis generates flux, while the q-axis generates torque. It has been found that the current defining the d-axis typically suffers losses compared to the current defining the q-axis, which generates torque. Therefore, if the processor configures the motor to transfer all generated electrical energy along the d-axis using FOC or vector control, there is no risk that the generated electrical energy will generate torque in the second motor.

[0050] This is useful in certain situations, such as when the loading and handling equipment is stationary on the rails 22a, 22b and the container lifting assembly is raising or lowering the container. In this case, the container lifting assembly motor 810 will act as the first motor, and one of the X / Y drive assembly motors 830 will act as the second motor. When the drive assembly motor 830 absorbs the electrical energy generated by the container lifting assembly motor 810, the absorbed energy will not be directed to the q-axis, and the loading and handling equipment will not move in the X / Y direction. Considering the opposite situation - one of the X / Y drive assembly motors 830 acts as the first motor and the container lifting assembly motor 810 acts as the second motor, there is no risk of the container clamping assembly being lowered when the loading and handling equipment moves along the rails 22a, 22b.

[0051] As described above, different motors can be used for X- and Y-direction travel, depending on the direction in which the load handling equipment moves along the track. Thus, if the first motor is responsible for X-direction travel (or X-direction), the second motor can be responsible for Y-direction travel (or X-direction). In this case, the set of wheels used for Y-direction travel (or X-direction) will not engage the track. Therefore, even if electrical energy is transferred to the q-axis (and thus torque is generated), there is no risk of the load handling equipment moving in the Y-direction (or X-direction). This eliminates the need for field-oriented control or vector control, simplifying the transfer of generated electrical energy.

[0052] Similarly, when acting as a second motor, the direction-changing assembly motor can be configured to not generate torque. Typically, when acting as a sink for electrical energy generated by the load handling equipment's first motor while performing its primary function (e.g., moving the load handling equipment, changing its direction, or lifting the container gripping assembly), the load handling equipment's second motor is prevented from performing its primary function (e.g., moving the load handling equipment, changing its direction, or lifting the container gripping assembly). More generally, the second motor is configured to absorb the electrical energy generated by the first motor in a manner that prevents the second motor from generating torque.

[0053] To ensure that the generated electrical energy is transferred along the d-axis, the d-axis of the second motor can be tracked, and the generated electrical energy can be directed along the last tracked orientation of the d-axis before the second motor acts as a sink for the electrical energy generated by the first motor. Alternatively, the q-axis can be tracked, and before the d-axis acts as a sink for the electrical energy generated by the first motor, the d-axis can be applied in a direction orthogonal to the last tracked orientation of the q-axis. Given that the d-axis and q-axis are orthogonal and relative to the rotor, tracking the position of the rotor can be used to determine the actual positions of the d-axis and q-axis. Unlike using the last known position of the d-axis before the second motor acts as a sink for the electrical energy generated by the first motor, the d-axis can be tracked in real time. This ensures that the d-axis can be used to sink current regardless of how the d-axis and q-axis move.

[0054] Figure 10 Shows how to implement Figure 9 Schematic diagram of the circuit blocks of the method in FIG. Figure 10 As shown, processor / controller 1010 is connected to power source 1020 (e.g., a battery), first motor 1030, bus circuit 1040, energy transfer circuit 1050, and second motor 1060. Processor / controller 1010 communicates with power source 1020 and first motor 1030 to drive the motors according to step 910. Bus circuit 1040 is connected to bus 1025 to monitor the voltage on bus 1025. Bus circuit 1040 is connected to processor / controller 1010 and energy transfer circuit 1050 to control the transfer of electrical energy upon detecting a threshold voltage on the bus. Bus circuit 1040 and energy transfer circuit 1050 can then transfer excess voltage on the bus to second motor 1060. Bus circuit 1040 and energy transfer circuit 1050 can be implemented using the PI controller described above. Processor / controller 1010 is connected to second motor 1060 to control the second motor to transfer energy generated by the first motor along its d-axis.

[0055] As used herein, the phrase "movement in the n-direction" (and related expressions) is intended to convey movement in any direction substantially along or parallel to the n-axis (i.e., toward the positive end of the n-axis or toward the negative end of the n-axis), where n is one of x, y, and z.

[0056] As used herein, the word “connect” and its derivatives are intended to encompass both direct and indirect connection possibilities. For example, “x is connected to y” is intended to encompass both the possibility of x being directly connected to y without intervening components, and the possibility of x being indirectly connected to y with one or more intervening components. When direct connection is intended, “directly connected,” “directly connected,” or similar expressions are used. Similarly, the word “supports” and its derivatives are intended to encompass both direct and indirect contact possibilities. For example, “x supports y” is intended to encompass both the possibility of x directly supporting and directly contacting y without intervening components, and the possibility of x indirectly supporting y with one or more intervening components contacting x and / or y. The word “mounted” and its derivatives are intended to encompass both direct and indirect mounting possibilities. For example, “x is mounted on y” is intended to encompass both the possibility of x being directly mounted on y without intervening components, and the possibility of x being indirectly mounted on y with one or more intervening components.

[0057] As used herein, the word "comprise" and its derivatives are intended to be open-ended rather than closed-ended. For example, "x includes y" is intended to include the possibility that x includes one and only one y, multiple ys, or one or more ys and one or more other elements. When a closed-ended nature is intended, "x consists of y" will be used to indicate that x includes only y and nothing else.

[0058] As used herein, a "controller" is intended to include any hardware suitable for controlling (e.g., providing instructions to) one or more other components. For example, a processor, equipped with one or more memories and appropriate software, is used to process data associated with the component or components and to send appropriate instructions to the component(s) to enable the component(s) to perform its intended function(s).

[0059] In this application, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms. It should also be understood that although the term "comprising" used in this specification indicates the presence of stated features, integers, steps, operations, elements and / or components, it does not prevent the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0060] The present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment containing both hardware and software elements.In a preferred embodiment, the present invention is implemented in software.

[0061] Furthermore, the present invention may take the form of a computer program embodied as a computer-readable medium having computer-executable code for use with a computer or in connection with a computer. For the purposes of this specification, a computer-readable medium is any tangible device that can contain, store, transmit, propagate, or transport a program for use with a computer or in connection with a computer. Furthermore, a computer-readable medium may be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device), or a propagation medium. Examples of computer-readable media include semiconductor or solid-state memory, magnetic tape, removable computer diskettes, random access memory (RAM), read-only memory (ROM), hard disks, and optical disks. Currently, examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read / write (CD-R / W), and DVD.

[0062] The flowchart in the figure shows the architecture, functionality and operation of possible implementations of the method according to various embodiments of the present invention. In this regard, each block in the flowchart can represent a module, segment or portion of code, which includes one or more executable instructions for implementing a specified logical function (one or more than one). It should also be noted that in some alternative embodiments, the functions mentioned in the blocks may not be performed in the order mentioned in the figure. For example, two blocks shown in succession may in fact be executed substantially simultaneously, or, depending on the functions involved, the blocks may sometimes be executed in a reversed order. It should also be noted that each block in the flowchart and the combination of blocks in the flowchart can be implemented by a dedicated hardware-based system (performing the specified function or behavior) or a combination of dedicated hardware and computer instructions.

[0063] It should be understood that the above description is made by way of example only and that various modifications may be made by those skilled in the art. Although various embodiments have been described above in some detail, or have been described with reference to one or more individual embodiments, those skilled in the art may make many changes to the disclosed embodiments without departing from the scope of the invention.

Claims

1. A system for consuming energy generated by a motor, the system comprising: First Motor; Second motor; as well as A controller configured to: driving the first motor; detecting electrical energy generated by the first motor; as well as The generated electrical energy is transferred to the second motor.

2. The system of claim 1, wherein: The controller is configured to control the second motor to absorb the generated electrical energy using field oriented control or vector control.

3. The system of claim 2, wherein: The controller is configured to absorb all of the generated electrical energy on the direct axis of the second motor using field oriented control or vector control.

4. A system as claimed in any preceding claim, wherein: The system includes a bus configured to deliver power to the first motor and / or the second motor, wherein the controller is configured to monitor a voltage on the bus to detect energy generated by the first motor.

5. The system of claim 5, wherein: The controller is configured to transfer the generated electrical energy to the second motor when the voltage on the bus reaches a threshold.

6. The system of claim 6, wherein: The controller is configured to divert the generated electrical energy until: The voltage on the bus is lower than the threshold; or the current limit of the second motor is reached; or The temperature limit of the second motor is reached.

7. A system as claimed in claim 6 when dependent on claim 3, wherein The set point of the direct axis current is increased until: The voltage on the bus is lower than the threshold; or the current limit of the second motor is reached; or The temperature limit of the second motor is reached.

8. A system as claimed in any preceding claim, wherein: The system includes a third motor, wherein the controller is configured to transfer a portion of the generated electrical energy to the third motor.

9. A system as claimed in any preceding claim, wherein: The system comprises a power source, such as a battery, wherein the controller is configured to transfer a portion of the generated electrical energy to the power source.

10. A system as claimed in any preceding claim, wherein: When dependent on claim 8, the second motor or the third motor comprises a multi-phase motor, such as a permanent magnet synchronous motor (PMSM).

11. A load handling plant comprising a system as claimed in any preceding claim.

12. The load handling apparatus of claim 11, wherein: The load handling equipment is configured to lift and move storage containers stacked in a grid frame structure comprising: a first set of parallel tracks or rails and a second set of parallel tracks or rails, the second set of parallel tracks or rails extending in a substantially horizontal plane substantially perpendicular to the first set of tracks or rails to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be vertically stacked between the uprights and vertically guided by the uprights through the plurality of grid spaces, the load handling apparatus comprising: a body or frame mounted on a first set of wheels configured to engage the first set of parallel tracks and a second set of wheels configured to engage the second set of parallel tracks; and a drive assembly comprising the first motor or the second motor, wherein the first motor or the second motor is configured to drive the first set of wheels or the second set of wheels to move the load handling device along the first set of parallel tracks or the second set of parallel tracks, respectively; and A container lifting assembly includes the other of the first motor or the second motor, wherein the other of the first motor or the second motor is configured to raise or lower a gripping device in the vertical direction.

13. The load handling equipment according to claim 11, wherein: The load handling equipment is configured to lift and move storage containers stacked in a grid frame structure comprising: a first set of parallel tracks or rails and a second set of parallel tracks or rails, the second set of parallel tracks or rails extending in a substantially horizontal plane substantially perpendicular to the first set of tracks or rails to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be vertically stacked between the uprights and vertically guided by the uprights through the plurality of grid spaces, the load handling apparatus comprising: a body or frame mounted on a first set of wheels configured to engage the first set of parallel tracks and a second set of wheels configured to engage the second set of parallel tracks; and a drive assembly comprising the first motor or the second motor, wherein the first motor or the second motor is configured to drive the first set of wheels or the second set of wheels to move the load handling device along the first set of parallel tracks or the second set of parallel tracks, respectively; and A change of direction assembly comprising the other of the first motor or the second motor, wherein the other of the first motor or the second motor is configured to raise or lower the first set of wheels relative to the body or frame and / or lower or raise the second set of wheels relative to the body or frame to engage and disengage the wheels from the parallel tracks.

14. The load handling equipment according to claim 11, wherein: The load handling equipment is configured to lift and move storage containers stacked in a grid frame structure comprising: a first set of parallel tracks or rails and a second set of parallel tracks or rails, the second set of parallel tracks or rails extending in a substantially horizontal plane substantially perpendicular to the first set of tracks or rails to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be vertically stacked between the uprights and vertically guided by the uprights through the plurality of grid spaces, the load handling apparatus comprising: a body or frame mounted on a first set of wheels configured to engage the first set of parallel tracks and a second set of wheels configured to engage the second set of parallel tracks; and a container lifting assembly, the container lifting assembly comprising the first motor or the second motor, wherein the first motor or the second motor is configured to raise or lower the clamping device in the vertical direction; and A change of direction assembly comprising the other of the first motor or the second motor, wherein the other of the first motor or the second motor is configured to raise or lower the first set of wheels relative to the body or frame and / or lower or raise the second set of wheels relative to the body or frame to engage and disengage the wheels from the parallel tracks.

15. The load handling apparatus of claim 11, wherein: The load handling equipment is configured to lift and move storage containers stacked in a grid frame structure comprising: a first set of parallel tracks or rails and a second set of parallel tracks or rails, the second set of parallel tracks or rails extending in a substantially horizontal plane substantially perpendicular to the first set of tracks or rails to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be vertically stacked between the uprights and vertically guided by the uprights through the plurality of grid spaces, the load handling apparatus comprising: a body or frame mounted on a first set of wheels configured to engage the first set of parallel tracks and a second set of wheels configured to engage the second set of parallel tracks; and a drive assembly comprising the first motor and the second motor, wherein the first motor is configured to drive the first set of wheels to move the load handling device along the first set of parallel tracks, and wherein the second motor is configured to drive the second set of wheels to move the load handling device along the second set of parallel tracks; and optionally, A change of direction assembly is configured to raise or lower the first set of wheels relative to the body or frame and / or lower or raise the second set of wheels relative to the body or frame to engage and disengage the wheels from the parallel tracks.

16. A method of transferring electrical energy using a system as claimed in any preceding claim, wherein: The method comprises: Use the controller to: driving the first motor; detecting electrical energy generated by the first motor; and The generated electrical energy is transferred to the second motor.

17. A computer program comprising instructions which, when executed by a computer, cause the computer to carry out the method according to claim 16.

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