Patent Application
20240275196
This document relates to energy management on work machines and in particular to techniques of safely drawing down power of the energy source of the work machines.
Powering a large electric-drive moving work machine (e.g., a wheel loader) requires a mobile electric energy source that can provide current of hundreds to thousands of Amperes (A) at hundreds to thousands of volts (V). This mobile energy source can include multiple large capacity battery cells connected in parallel as battery strings that provide the sustained energy power needed by the work machine. High-capacity cables connect to the energy source and route the electric power between various compartments of the work machine. Because the large-capacity energy source includes batteries, the energy source does not shut off and its electric potential remains available. Therefore, electric work machines need a safe and reliable technique to draw down the charge of the large-capacity energy source to allow for safe servicing of the work machines.
U.S. Pat. No. 9,614,383 discusses a system for providing energy management and maintenance of a high energy battery pack having a self-discharger to discharge energy from the battery pack.
Large moving work machines use a large capacity energy source that sources high voltage electrical energy to the work machine. The large capacity energy sources can be based on large capacity batteries that do not shut off. Equipment can be damaged if the large capacity energy source is not disabled safely when performing maintenance on the work machine. Also, maintenance of work machines poses a threat of injury to workers from the high voltages and currents of the large capacity energy source.
An example work machine can include battery cells connected to form a battery system. The work machine can include a load bus to distribute energy from the battery system to components of the work machine. The work machine can include a battery discharge controller coupled between the battery system and the load bus. The battery discharge controller can control the load bus to discharge the battery cells by providing power from the battery system to at least one component of the work machine. The work machine can include a user input device to receiver user input to initiate battery discharge.
An example energy system can include battery cells connected to form a battery system. The energy system can include a load bus to distribute energy from the battery system to components of a work machine. The energy system can include a battery discharge controller coupled between the battery system and the load bus. The battery discharge controller can control the load bus to discharge the battery cells by providing power from the battery system to at least one component of the work machine.
A method for managing battery discharge on a work machine can include receiving a user input requesting battery discharge of a battery system of the work machine. The method can include, responsive to receiving the user input, establishing electrical communication between the battery system and at least one machine component of the work machine. The method can include providing at least one electrical discharge path between the battery system and the at least one machine component. The method can include detecting charge level of the battery system while discharging the battery system on the electrical discharge path. The method can include terminating discharging upon detection that the charge level is below a threshold.
Examples according to this disclosure are directed to methods and devices for managing high voltage electrical energy provided to electrical circuits and electrical motors of a work machine. Techniques for drawing down the power in an energy system of a mobile work machine are described.
Machine 100 includes frame 102 mounted on four wheels 104, although, in other examples, the machine could have more or fewer than four wheels. Frame 102 is configured to support and/or mount one or more components of machine 100. For example, machine 100 includes enclosure 108 coupled to frame 102. Enclosure 108 can house, among other components, an electric motor to propel the machine over various terrain via wheels 104. In some examples, multiple electric motors are included in multiple enclosures at multiple locations of the machine 100.
Machine 100 includes implement 106 coupled to the frame 102 through linkage assembly 110, which is configured to be actuated to articulate bucket 112 of implement 106. Bucket 112 of implement 106 may be configured to transfer material such as, soil or debris, from one location to another. Linkage assembly 110 can include one or more cylinders 114 configured to be actuated hydraulically or pneumatically, for example, to articulate bucket 112. For example, linkage assembly 110 can be actuated by cylinders 114 to raise and lower and/or rotate bucket 112 relative to frame 102 of machine 100.
Platform 116 is coupled to frame 102 and provides access to various locations on machine 100 for operational and/or maintenance purposes. Machine 100 also includes an operator cabin 118, which can be open or enclosed and may be accessed via platform 116. Operator cabin 118 may include one or more control devices (not shown) such as, a joystick, a steering wheel, pedals, levers, buttons, switches, among other examples. The control devices are configured to enable the operator to control machine 100 and/or the implement 106. Operator cabin 118 may also include an operator interface such as, a display device, a sound source, a light source, or a combination thereof.
Machine 100 can be used in a variety of industrial, construction, commercial or other applications. Machine 100 can be operated by an operator in operator cabin 118 or a remote operator. The operator can, for example, drive machine 100 to and from various locations on a work site and can also pick up and deposit loads of material using bucket 112 of implement 106. Autonomous operation is also possible. As an example, machine 100 can be used to excavate a portion of a work site by actuating cylinders 114 to articulate bucket 112 via linkage 110 to dig into and remove dirt, rock, sand, etc. from a portion of the work site and deposit this load in another location. Machine 100 can include a battery compartment connected to frame 102 and including a battery system 120. Battery system 120 is electrically coupled to the one or more electric motors of the machine 100. Battery system 120 can include discharge control circuitry 122 for implementing operations for controlled battery discharge as described herein.
The battery system 120 can include multiple small battery cells arranged or combined into a large battery pack. For example, cells can be 3.2-3.7 volts and 2-304 Ah. The battery back can include in total 750 Volts. 80 Amp-hour battery, or 60 kilowatt-hours), to provide a high-capacity electrical energy source. The battery cells 224 (
A battery system 120 may be used to provide a high voltage, high direct current (DC) electrical energy source (e.g., 700V-3000V and 300A-1000+A). The output of the battery system may be provided to a converter or inverter to produce a high voltage, high alternating current (AC) electrical energy source. The energy source or sources provide electrical power to electrical motors, pumps, circuits, etc., of the machine 100 including some components described herein with respect to
Vehicles hold large amounts of potential energy in energy sources, even after the vehicles stop operation. Such energy can complicate maintenance operations. In addition to maintenance operations the battery may be placed at a reduced state or level of charge during transportation or storage, or to lower the potential energy risk when the battery is inside of a building It can be dangerous to perform maintenance or diagnostic work on a work machine while the energy source is fully charged. In addition, some industry standards or employer standards may have an upper charge level limit above which a battery cannot be charged while maintenance work is being implemented on the work machine.
Systems and methods according to embodiments address these and other concerns by providing a battery discharge feature to bring the battery to a lower state of charge in a controlled fashion and in a safe location (e.g., in a maintenance bay or other controllable environment). The controlled battery discharge feature can utilize energy from a battery or system of batteries to provide power to one or more systems/components of the work machine 100 until a state of charge of the battery drops below a predetermined threshold (e.g., 50% charge or other value as determined according to industry standards, owner determination, mechanic determination, etc.) The controlled battery discharge feature can reduce or risk to an operator during maintenance/service operation. The threshold can be stored in memory of any computing system remote or local to the work machine or processor 214, or entered as a user preference, or programmed as a constant into the processor 214. The threshold can thereafter be retrieved from memory or programmed into the battery discharge controller.
The battery system 120 provides high-voltage high-current electrical energy to a load bus 226. The load bus 226 distributes electrical power to different areas or components of the work machine 100 including, for example, heating, ventilation, and air conditioning (HVAC) cooling system 202, an HVAC heating system 204, a hydraulic charge system 206, cooling fans 208, heating grid 210, electric motor(s) 211 and thermal management system 212. Some examples may not include an HVAC heating system 204 or an HVAC cooling system 202. For example, work machines 100 that do not include an operator cab will typically not include an HVAC heating system 204 or an HVAC cooling system 202. Other systems capable of drawing electrical power can also be included, and more than one of each type of system can be included, on the work machine 100 and coupled to the load bus 226. The HVAC cooling system 202, HVAC heating system 204, hydraulic charge system 206, cooling fans 208, heating grid 210, and thermal management system 212, as well as any other electrical systems not shown, can selectively (or as a group with other components) receive power during a discharge process.
The discharge control circuitry 122 can include processor 214, switches or other circuitry to selectively connect the battery system 223 to one or more of the HVAC cooling system 202, HVAC heating system 204, hydraulic charge system 206, cooling fans 208, beating grid 210, and thermal management system 212, as well as any other electrical systems not shown. The discharge control circuitry 122 can connect different cells of a multi-cell battery system 223 to the load bus 226 or to different systems/components or groups of systems/components including the HVAC cooling system 202, HVAC heating system 204, hydraulic charge system 206, cooling fans 208, heating grid 210, and thermal management system 212, as well as any other electrical systems.
The discharge control circuitry 122 can include measurement circuitry 216 to measure charge of the battery system 223 and other parameters for measuring health of the battery system 223. The discharge control circuitry 122 can comprise a service tool connectable to the battery system 223 or the discharge control circuitry 122 can comprise buttons or switches of the work machine, e.g., behind fuse panels or incorporated in fuse boxes, etc. The discharge control circuitry 122 can include a user display or the discharge control circuitry 122 can be coupled to a user display 218 either on the work machine 100 (e.g., in operator cabin 118 (
The discharge control circuitry 122 can control the discharge process to discharge the battery cells 224 at different speeds or rates. For example, if rapid discharge is desired, the discharge control circuitry 122 can increase the amount of current draw or provide discharge through high energy usage components through which more energy can be discharged (or discharged more rapidly), such as, for example, hydraulic charge system 206. A resistive heating grid 210 can be added to the load bus 226 to provide additional energy draw from the battery cells 224. In some examples including multiple battery packs, the multiple battery packs may be at different states of charge. However, this is not typical since the battery packs are connected together and the pack voltages (state of charge) will balance out over time. The battery management system (BMS) can work to balance cell voltages within each battery pack. If a slow discharge rate is desired, the discharge control circuitry 122 can decrease the amount of current draw or provide discharge through components through which less energy can be discharged (or discharged more slowly), such as, for example, a cooling fan.
The method 300 can begin with operation 302 with the discharge control circuitry 122 receiving a user input requesting battery discharge of a battery system 120 of the work machine 100. The user input can be provided through push buttons, switches, touch screens, etc., either on a service tool or the user display, or as switches on the work machine 100 itself.
The method 300 can continue with operation 304 with the discharge control circuitry 122 establishing electrical communication between the battery system 120 and at least one machine component of the work machine 100. For example, connection can be established to the HVAC cooling system 202, the HVAC heating system 204, hydraulic charge system 206, cooling fan/s 208, heating grid 210, or thermal management system/s 212 among other components. Some types of work machines may not include all of the above components, and some work machines may include other components through which battery discharge can occur.
The method 300 can continue with operation 306 with the discharge control circuitry 122 (in conjunction with the load bus 226, for example) providing at least one electrical discharge path between the battery system 120 and the at least one machine component 202, 204, 206, 208, 210, 212. At operation 308, the discharge control circuitry 122 (using, for example, measurement circuitry 216) can detect the charge level of the battery system 223 while discharging the battery system 120 on the electrical discharge path. At operation 310, if the charge level falls or declines below a preferred threshold, the discharge control circuitry 122 can terminate discharge, otherwise, the process can loop back to operation 306 and discharging can continue. Throughout method 300, the discharge control circuitry 122 can provide visual or other updates as to status and progress to a user through a user display, audio alarm, etc.
In an operating example of an energy source for a mobile work machine according to this disclosure, it is desired for technicians or other maintenance workers to perform maintenance on the work machine. The high-capacity energy source can be battery-based, or fuel-cell based, and does not shut off like a combustion engine. When maintenance is to be performed on the work machine, it is desired to protect the workers from coming into contact with the high voltage and high current of the energy source. Battery control circuitry allows for connection of the battery to different systems on the work machine, and for initiation of a discharge operation to draw battery voltage or charge below a threshold.
The above detailed description is intended to be illustrative, and not restrictive. The scope of the disclosure should, therefore, be determined with references to the appended claims, along with the full scope of equivalents to which such claims are entitled.
