Energy management method and equipment for electric excavator and medium

Abstract

The invention discloses an energy management method and device for an electric excavator and a medium, and relates to the field of energy recovery, and the method comprises the steps that a corresponding energy management strategy is selected based on a power supply mode; obtaining the charge state of the battery module, and determining a preset charge interval hit in the energy management strategy according to the charge state; performing energy management on the electric excavator according to the sub-management strategy corresponding to the preset charge interval; the sub-management strategy comprises an energy recovery strategy, energy recovery is carried out through a big arm energy recovery module and / or a rotation energy recovery module of the electric excavator, and the battery module is charged. Through the synergistic effect of the big arm energy recovery module and the rotation energy recovery module, big arm descending potential energy and rotation braking kinetic energy are converted into electric energy to be stored in the battery module, energy waste is reduced, and the energy recovery efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of energy recovery, and specifically to an energy recovery method, device, and medium for electric excavators. Background Art

[0002] In the field of modern construction machinery, fuel excavators consume a large amount of fuel and cause serious environmental pollution. Electric excavators have gradually attracted attention due to their advantages such as high efficiency and environmental protection.

[0003] However, in the actual working process, since the working scenarios of excavators are usually industrial scenarios, involving frequent working conditions such as the boom descending and slewing braking, the energy consumption of electric excavators is huge during the working process, and a large amount of energy is wasted in the form of heat energy, mechanical energy, etc.

[0004] Based on this, an energy management solution for electric excavators is needed. Summary of the Invention

[0005] To solve the above problems, this application proposes an energy management method for electric excavators, including: Determine the power supply mode of the vehicle system of the electric excavator, and select a corresponding energy management strategy based on the power supply mode; Obtain the state of charge of the battery module, and determine the preset state-of-charge interval hit in the energy management strategy according to the state of charge; Perform energy management on the electric excavator according to the sub-management strategy corresponding to the preset state-of-charge interval; Among them, the sub-management strategy includes an energy recovery strategy, and energy is recovered through the boom energy recovery module and / or slewing energy recovery module of the electric excavator to charge the battery module; In the energy recovery strategy, energy recovery is achieved by controlling the numerical relationship between the discharge voltage of the power grid module, the charging voltage of the battery module, the discharge voltage of the battery module, and the DC bus voltage.

[0006] In one example, when the power supply mode is battery-only power supply, performing energy management on the electric excavator according to the sub-management strategy corresponding to the preset state-of-charge interval specifically includes: For the lowest first preset state-of-charge interval, perform a low-battery alarm; For the second preset charge interval higher than the first preset state-of-charge interval, while supplying power to the vehicle system through the battery module, execute the energy recovery strategy; For the third preset charge interval higher than the second preset state-of-charge interval, supply power to the vehicle system through the battery module.

[0007] In one example, when the power supply mode is grid combined with battery power supply, according to the sub-management strategy corresponding to the preset state of charge interval, energy management is performed on the electric excavator, specifically including: For the lowest first preset state of charge interval, while the grid module supplies power to the vehicle system, the grid module charges the battery module, and the energy recovery strategy is executed; For the second preset charge interval higher than the first preset state of charge interval, while the grid module and the battery module supply power to the vehicle system, the energy recovery strategy is executed; For the third preset charge interval higher than the second preset state of charge interval, the battery module supplies power to the vehicle system, and the energy recovery strategy is executed.

[0008] In one example, the vehicle system includes: a boom energy recovery module, a slewing energy recovery module, a hydraulic pump module, a battery module, a grid module, and a DC bus; The boom energy recovery module is connected to the DC bus through a boost DC-DC converter, and conveys the electric energy obtained by energy recovery to the DC bus; The slewing energy recovery module is connected to the DC bus, and conveys the electric energy obtained by energy recovery to the DC bus; The hydraulic pump module includes a motor controller and a hydraulic pump. The motor controller is connected to the DC bus, and the motor controller drives the hydraulic pump to work by receiving the electric energy conveyed by the DC bus; The battery module is connected to the DC bus through a bidirectional DC-DC converter, receives the electric energy conveyed by the DC bus for charging, and / or conveys the electric energy to the DC bus; The grid module is connected to the DC bus through a rectification module, and conveys the electric energy to the DC bus.

[0009] In one example, it is defined that the discharge voltage of the grid module through the rectification module is the first voltage, the charging voltage of the battery module through the bidirectional DC-DC converter is the second voltage, and the discharge voltage of the battery module through the bidirectional DC-DC converter is the third voltage; When the power supply mode is battery-only power supply or grid combined with battery power supply, the voltage control strategy includes: When the energy recovery strategy is executed, the DC bus voltage is greater than the second voltage; The second voltage is greater than the third voltage; When the power supply mode is grid combined with battery power supply, the voltage control strategy includes: For the first preset state of charge interval, the first voltage is greater than the second voltage; For a second preset charge range, the second voltage is greater than the first voltage, and the first voltage is greater than the third voltage; For a third preset charge range, the third voltage is greater than the first voltage.

[0010] In one example, the boom energy recovery module includes, connected in sequence: a proportional valve, a boom hydraulic motor, a generator, a rectifier bridge, and a boost DC-DC converter; Energy recovery is performed through the boom energy recovery module of the electric excavator to charge the battery module, which specifically includes: Obtain the opening degree of the boom lowering handle, and determine the opening degree of the control proportional valve according to the opening degree of the boom lowering handle; wherein, the opening degree of the boom lowering handle is negatively correlated with the opening degree of the control proportional valve; Adjust the flow rate of the high-pressure hydraulic oil for boom lowering flowing into the boom hydraulic motor through the proportional valve; Drive the generator through the high-pressure hydraulic oil by the boom hydraulic motor; Convert mechanical energy into AC electrical energy through the generator; Convert AC electrical energy into DC electrical energy through the rectifier bridge; Boost the DC electrical energy through the boost DC-DC converter, and deliver the boosted DC electrical energy to the DC bus.

[0011] In one example, the slewing energy recovery module includes a slewing hydraulic motor and a low-speed high-torque motor; Energy recovery is performed through the slewing energy recovery module of the electric excavator to charge the battery module, which specifically includes: Obtain the opening degree of the slewing handle; When the opening degree of the slewing handle is greater than a preset slewing opening value, obtain the slewing speed; When the slewing speed is lower than a preset speed, control the slewing hydraulic motor and the low-speed high-torque motor to operate; When the slewing speed is higher than a preset speed, control the slewing hydraulic motor to close, and separately control the low-speed high-torque motor to operate; When the opening degree of the slewing handle is reduced to be lower than the preset slewing opening value, control the slewing hydraulic motor to close, and control the low-speed high-torque motor to decelerate, convert the slewing energy into electrical energy, and deliver it to the DC bus.

[0012] In one example, the vehicle system further includes: a thermal-electric coupled energy recovery module; The thermoelectric coupling energy recovery module includes: a phase change material coating, a thermoelectric power generation chip, and a heat sink; the phase change material coating is coated on the surface of the motor and / or the surface of the motor, and the thermoelectric power generation chips are distributed in an array and cover a preset heat generation area; The method further includes: Determine to trigger a preset thermoelectric coupling scenario according to the recent working records of the electric excavator and / or the current working environment; Perform energy recovery through the thermoelectric coupling energy recovery module to charge the battery module, specifically including: Absorb the heat generated during the operation of the motor and / or the motor through the phase change material coating; Convert the heat absorbed by the phase change material coating into direct current power through the thermoelectric power generation chips and the heat sink; Boost the direct current power converted by the thermoelectric power generation chips through a boost DC-DC converter to obtain a fourth voltage; When the power supply mode is grid combined with battery power supply, the voltage control strategy includes: For the first preset state of charge interval, the first voltage is greater than the fourth voltage, and the fourth voltage is greater than the second voltage; For the second preset charge interval, the second voltage is greater than the fourth voltage, and the fourth voltage is greater than the first voltage, and the first voltage is greater than the third voltage; For the third preset charge interval, the third voltage is greater than the fourth voltage, and the fourth voltage is greater than the first voltage.

[0013] On the other hand, the present application also proposes an energy management device for an electric excavator, including: At least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the energy management method for an electric excavator as described in the above example.

[0014] On the other hand, the present application also proposes a non-volatile computer storage medium storing computer executable instructions, and the computer executable instructions are set to: the energy management method for an electric excavator as described in the above example.

[0015] The energy management method for an electric excavator proposed by the present application can bring the following beneficial effects: 1. Through the synergistic effect of the boom energy recovery module and the slewing energy recovery module, the potential energy of the descending boom and the kinetic energy of the slewing brake are converted into electrical energy and stored in the battery module, reducing energy waste and improving the energy recovery efficiency.

[0016] 2. Based on the dynamic range management strategy of the state of charge of the battery, accurately match different charge intervals, avoid overcharging and over-discharging of the battery, optimize the battery performance, and extend the battery life.

[0017] 3. The energy recovery and dynamic management strategy cooperate to reduce the overall energy consumption of the system, reduce the dependence on external charging, and reduce the long-term use cost of the electric excavator.

[0018] 4. Through efficient energy recovery and management, reduce the waste of electrical energy and battery loss, indirectly reduce carbon emissions and resource consumption, and improve the environmental protection benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments and descriptions thereof of the present application are used to explain the present application, and do not constitute an improper limitation of the present application. In the drawings: Figure 1 is a schematic flowchart of the energy management method for an electric excavator in an embodiment of the present application; Figure 2 is a schematic diagram of the modules of the vehicle system in a certain situation in an embodiment of the present application; Figure 3 is a schematic diagram of the energy management device for an electric excavator in an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be clearly and completely described below in conjunction with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0021] The following will describe in detail the technical solutions provided by the embodiments of the present application with reference to the drawings.

[0022] As Figure 1 shown, an embodiment of the present application provides an energy management method for an electric excavator, including: S101: Determine the power supply mode of the vehicle system of the electric excavator, and select the corresponding energy management strategy based on the power supply mode.

[0023] For an electric excavator, its power supply methods mainly include internal batteries and / or an external power grid. In the embodiments of this application, two main power supply modes are involved, namely, battery-only power supply and grid combined with battery power supply. Of course, in actual operation, other power supply modes can also be set, and corresponding energy management strategies can be set. For example, a power supply mode of grid-only power supply can be set, or a power supply mode of multiple external power grids in hybrid power supply can be set, etc.

[0024] For different power supply modes, corresponding energy management strategies are respectively set. Through the energy management strategies, energy management in the electric excavator is achieved. For example, it includes charging management, discharging management of electric energy, and the mutual conversion between electric energy and mechanical energy, etc.

[0025] S102: Obtain the state of charge of the battery module, and determine the preset state-of-charge interval hit in the energy management strategy according to the state of charge.

[0026] The state of charge, also known as SOC (State of Charge) power, refers to the ratio of the remaining power to the total battery capacity under certain conditions of the battery, usually expressed as a percentage.

[0027] Multiple preset state-of-charge intervals are set in the energy management strategy, and each preset state-of-charge interval has an upper limit and a lower limit value. The number of preset state-of-charge intervals and the upper limit and lower limit values can be set based on actual situations.

[0028] S103: Perform energy management on the electric excavator according to the sub-management strategy corresponding to the preset state-of-charge interval.

[0029] Among them, the sub-management strategy includes an energy recovery strategy. Through the boom energy recovery module and / or the slewing energy recovery module of the electric excavator, energy recovery is carried out to charge the battery module; In the energy recovery strategy, energy recovery is achieved by controlling the numerical relationship between the discharge voltage of the grid module, the charging voltage of the battery module, the discharge voltage of the battery module, and the DC bus voltage.

[0030] In the energy management strategy, a corresponding strategy is set for each preset state-of-charge interval. Here, the strategy corresponding to each preset state-of-charge interval is called a sub-management strategy.

[0031] In some sub-management strategies, an energy recovery strategy may be included. The energy recovery strategy refers to that during the operation of the energy recovery structure (such as including the boom energy recovery module and the slewing energy recovery module) set in the electric excavator, the excess energy (such as including kinetic energy, potential energy, etc.) generated is converted into hydraulic energy, and then the hydraulic energy is converted into electric energy, so as to charge the battery module.

[0032] 1. Through the synergistic effect of the boom energy recovery module and the slewing energy recovery module, the potential energy of the descending boom and the kinetic energy of the slewing braking are converted into electrical energy and stored in the battery module, reducing energy waste and improving the energy recovery efficiency.

[0033] 2. Based on the dynamic range management strategy of the state of charge of the battery, different charge intervals are accurately matched to avoid overcharging and over-discharging of the battery, optimize the battery performance, and extend the battery life.

[0034] 3. The energy recovery and the dynamic management strategy cooperate to reduce the overall energy consumption of the system, reduce the dependence on external charging, and lower the long-term use cost of the electric excavator.

[0035] 4. Through efficient energy recovery and management, the waste of electrical energy and battery loss are reduced, indirectly reducing carbon emissions and resource consumption, and enhancing the environmental protection benefits.

[0036] In one embodiment, as Figure 2 shown, the vehicle system includes: a boom energy recovery module, a slewing energy recovery module, a hydraulic pump module, a battery module, and a power grid module.

[0037] Among them, the boom energy recovery module is mainly used to recover energy using potential energy when the boom descends and finally convert it into electrical energy. It is connected to the DC bus through a boost DC-DC converter (boost DCDC) and conveys the electrical energy obtained from energy recovery to the DC bus.

[0038] The slewing energy recovery module is mainly used to recover energy using kinetic energy when the electric excavator slews and finally convert it into electrical energy. It is connected to the DC bus and conveys the electrical energy obtained from energy recovery to the DC bus.

[0039] The hydraulic pump module includes a motor controller and a hydraulic pump. The motor controller is connected to the DC bus. The motor controller drives the hydraulic pump (commonly known as the main pump) to work by receiving the electrical energy conveyed by the DC bus. The hydraulic pump can drive the hydraulic motors in the boom and the slewing device to work.

[0040] The battery module is connected to the DC bus through a bidirectional DC-DC converter (bidirectional DCDC). In different sub-management strategies corresponding to different power supply modes, it may perform charging actions, discharging actions respectively, or may even discharge while charging. Therefore, it may receive the electrical energy conveyed by the DC bus for charging and / or convey electrical energy to the DC bus, that is, perform discharging.

[0041] The power grid module is connected to an external power grid and is connected to the DC bus through a rectifier module to convey electrical energy to the DC bus.

[0042] For convenience of description, the discharge voltage of the power grid module through the rectification module is defined as the first voltage U1 here, the charging voltage of the battery module through the bidirectional DC-DC converter is defined as the second voltage U2, and the discharge voltage of the battery module through the bidirectional DC-DC converter is defined as the third voltage U3. The range of the state of charge is defined as 0 to 100%.

[0043] Based on the characteristics of the bidirectional DC-DC converter, whether the power supply mode is battery-only power supply or grid-and-battery power supply, the second voltage is greater than the third voltage. Of course, when implementing the energy recovery strategy, it is necessary to set the DC bus voltage greater than the second voltage to enable charging of the TV module.

[0044] In one embodiment, as Figure 2 shown, the boom energy recovery module includes, connected in sequence: a proportional valve (for adjusting the flow rate of the high-pressure hydraulic oil for the boom to descend into the hydraulic motor), a boom hydraulic motor (for driving a generator using the high-pressure hydraulic oil), a generator (for converting the rotational mechanical energy into three-phase alternating current), a rectifier bridge (for rectifying the three-phase alternating current output by the generator into direct current), and a boost DC-DC converter (for boosting the rectified direct current to the system charging voltage).

[0045] When performing energy recovery, first obtain the opening of the boom lowering handle, and determine the opening of the control proportional valve according to the opening of the boom lowering handle; among them, the opening of the boom lowering handle is negatively correlated with the opening of the control proportional valve.

[0046] In actual work, the flow rate of the high-pressure hydraulic oil for the boom to descend into the boom hydraulic motor is adjusted through the proportional valve; the generator is driven by the high-pressure hydraulic oil through the boom hydraulic motor; the mechanical energy is converted into AC electrical energy through the generator; the AC electrical energy is converted into DC electrical energy through the rectifier bridge; the DC electrical energy is boosted through the boost DC-DC converter, and the boosted DC electrical energy is delivered to the DC bus.

[0047] For example, the opening range of the boom lowering handle is defined as 0 to 100%. When the opening of the boom lowering handle is less than the first preset lowering opening value, it is considered that the required boom lowering speed is relatively small at this time, and the opening of the control proportional valve can be directly set to a relatively high value (for example, 90% to 100%). Most or all of the boom lowering hydraulic oil is discharged through the boom hydraulic motor, and then the boom hydraulic motor drives the generator to generate electricity, thereby generating electrical energy and delivering it to the DC bus.

[0048] When the opening of the boom lowering handle is greater than the first preset lowering opening value and less than the second preset lowering opening value (which is higher than the first preset lowering opening value), in this working condition, while considering the required speed of the boom lowering and taking into account energy recovery, the opening of the proportional valve set at a relatively high value is reduced to a preset value Q. This enables part of the hydraulic oil for boom lowering to return to the fuel tank through the original vehicle oil circuit to ensure the boom lowering speed, while the remaining part of the hydraulic oil for boom lowering flows into the hydraulic motor to drive the generator for power generation.

[0049] When the opening of the boom lowering handle is greater than the second preset lowering opening value, the opening of the proportional valve can be further reduced, or the opening of the proportional valve can be maintained at the Q value. This value can ensure the normal boom lowering speed, meet the driver's operation, and at the same time enable part of the energy recovery during boom lowering.

[0050] In one embodiment, as Figure 2 shown, the slewing energy recovery module includes a slewing hydraulic motor and a low-speed high-torque motor. Generally, there are multiple slewing hydraulic motors in an electric excavator. Taking the example of including two slewing hydraulic motors, one of the slewing hydraulic motors can be replaced with a low-speed high-torque motor. Additionally, before replacing the low-speed high-torque motor, the functional relationship between the slewing handle opening of the electric excavator's two slewing hydraulic motors and the excavator's slewing speed can be calibrated to facilitate the subsequent acquisition of the slewing speed.

[0051] Define the slewing handle opening range as 0 - 100% and obtain the slewing handle opening.

[0052] When the slewing handle opening is less than the preset slewing opening value, it is considered at this time that the electric excavator does not perform a slewing action, and the system controls the slewing hydraulic motor to operate to maintain the non-rotation action of the excavator.

[0053] When the slewing handle opening is greater than the preset slewing opening value, obtain the slewing speed. It can be obtained through the functional relationship calibrated above, or it can be obtained in real time by installing a sensor.

[0054] When the slewing speed is lower than the preset speed V1, this stage is defined as the excavator slewing start-up stage. In this stage, a relatively large starting torque is required. Control the slewing hydraulic motor and the low-speed high-torque motor to operate, and set the target speed to V1 to quickly reach V1 for the slewing speed.

[0055] When the slewing speed is higher than the preset speed, it is considered that the slewing start-up stage is completed, and the excavator enters the slewing stage. In this stage, the required slewing torque is less than the slewing starting torque. Control the slewing hydraulic motor to close and separately control the low-speed high-torque motor to operate.

[0056] When the opening of the slewing handle starts to decrease from large to small until it drops below the preset opening value (even resets to 0), this stage is defined as the slewing deceleration and stop stage. Still control the slewing hydraulic motor to close and control the low-speed high-torque motor to decelerate, convert the slewing energy into electrical energy, and transmit it to the DC bus. Among them, this energy recovery aims at maximum energy recovery, without current limit for recovery, and performs braking energy feedback with the maximum current and voltage of the motor controller as the goal to achieve maximum energy recovery.

[0057] In one embodiment, when the power supply mode is battery-only power supply, the energy management strategy can be set as follows: from the state of charge from low to high, there are successively a first preset state-of-charge interval, a second preset state-of-charge interval, and a third preset state-of-charge interval.

[0058] When the state of charge is lower than the value A (this value is a preset value set based on the actual working state of the electric excavator), it is considered to hit the lowest first preset state-of-charge interval. At this time, a low-battery alarm is given.

[0059] When the state of charge is higher than the value A and lower than the value B (this value is a preset value set based on the actual working state of the electric excavator), it is considered to hit the second preset charge interval higher than the first preset state-of-charge interval. While the battery module supplies power to the vehicle system, the energy recovery strategy is executed. The system controls the bidirectional DC-DC converter to discharge at the third voltage U3 to supply power to the entire vehicle system. When the boom energy recovery module and / or the slewing energy recovery module perform energy recovery, the DC bus voltage will exceed the second voltage U2. At this time, the system controls the bidirectional DC-DC converter to charge the battery module to achieve energy recovery and maintain the DC bus voltage not exceeding the second voltage U2.

[0060] When the state of charge is higher than the value B, it is considered to hit the third preset charge interval higher than the second preset state-of-charge interval. At this time, it is considered that the battery has sufficient power and there is no need for energy recovery. In this state, the vehicle system turns off the boom energy recovery module and the slewing energy recovery module and continues to supply power to the vehicle system through the battery module.

[0061] In one embodiment, when the power supply mode is grid-connected battery power supply, the external grid power supply method can be to use the AC 380V power after passing through the rectification module to supply power to the electric excavator, and at the same time, the on-vehicle battery module can also supply power to the vehicle system to achieve hybrid energy power supply for the electric excavator. The energy management strategy for grid-connected battery power supply can be set as follows: from the state of charge from low to high, there are successively a first preset state-of-charge interval, a second preset state-of-charge interval, and a third preset state-of-charge interval.

[0062] It should be noted here that in the case of the battery supplying power alone and the grid combined with the battery to supply power, the upper and lower limit values of the first preset state of charge range, the second preset state of charge range, and the third preset state of charge range can be the same, or can be set to different values based on requirements. Of course, more or fewer preset state of charge ranges can also be set or modified in the energy management strategies of various power supply modes based on requirements.

[0063] For the convenience of description, the same upper and lower limit values of the two are selected for description here.

[0064] When the state of charge is lower than the value A, it is considered to hit the lowest first preset state of charge range. In this state, the battery has a low power level, and the battery module needs to be charged. At the same time, the power demand of the motor also needs to be met. Therefore, while the grid module supplies power to the vehicle system, the grid module charges the battery module and executes the energy recovery strategy.

[0065] Based on this, the charging voltage U2 of the bidirectional DC-DC converter to the battery module can be set to be less than the output DC voltage U1 of the rectification module by a certain value (that is, the voltage control strategy is set to the first voltage being greater than the second voltage). In this state, the output DC voltage U1 of the rectification module can not only charge the battery module through the bidirectional DC-DC converter, but also supply power to the motor. At the same time, when the boom energy recovery module and / or the slewing energy recovery module perform energy recovery, the DC bus voltage will be greater than the second voltage U2. At this time, the system controls the bidirectional DC-DC converter to charge the battery module to achieve energy recovery.

[0066] When the state of charge is higher than the value A and lower than the value B, it is considered to hit the second preset charge range higher than the first preset state of charge range. In this state, it is considered that the battery power level is not low, and there is no need to use the direct current output by the rectification module of the grid module to charge the battery module. The battery charging only needs to receive the electric energy recovered by the boom energy recovery module and / or the slewing energy recovery module. That is, while the grid module and the battery module supply power to the vehicle system, the energy recovery strategy is executed.

[0067] Based on this, the charging voltage U2 of the bidirectional DC-DC converter to the battery module is set to be greater than the output DC voltage U1 of the rectification module by a certain value (that is, the voltage control strategy is set to the second voltage being greater than the first voltage), and the discharge voltage U3 of the battery module after passing through the bidirectional DC-DC converter is set to be less than U1 by a certain value (that is, the voltage control strategy is set to the first voltage being greater than the third voltage).

[0068] Since the second voltage is greater than the first voltage, the first voltage U1 output by the rectification module of the power grid module does not charge the battery module. Since the first voltage is greater than the third voltage, when the electric excavator performs heavy-load work, the first voltage output by the rectification module of the power grid module is unstable, and the first voltage U1 drops significantly instantaneously, resulting in an overcurrent in the vehicle system.

[0069] When the electric excavator is performing heavy-load work and the first voltage U1 drops to the set third voltage U3, the battery module discharges to the DC bus of the vehicle system through the bidirectional DC-DC converter to make up for the fluctuations of the power grid module, so that the DC bus voltage of the vehicle system is not lower than the third voltage U3, thus solving the above problem.

[0070] Of course, when the boom energy recovery module and / or the slewing energy recovery module perform energy recovery, the DC bus voltage will be greater than the second voltage U2 set in this state. At this time, the vehicle system controls the bidirectional DC-DC converter to charge the battery module to achieve energy recovery and maintain the DC bus voltage not exceeding the second voltage U2.

[0071] When the state of charge is higher than the B value, it is considered that it hits the third preset charge interval higher than the second preset charge interval. At this time, the discharge voltage U3 of the battery module after passing through the bidirectional DC-DC converter can be set to be greater than the voltage U1 output by the rectification module of the power grid module (that is, the voltage control strategy is set so that the third voltage is greater than the first voltage). At this time, the power supply of the vehicle system all comes from the battery module and does not require the electric energy of the power grid module. That is, the vehicle system is powered by the battery module and the energy recovery strategy is executed. When the boom energy recovery module and / or the slewing energy recovery module perform energy recovery, the DC bus voltage will be greater than the second voltage U2 set in this state. At this time, the vehicle system controls the bidirectional DC-DC converter to charge the battery module to achieve energy recovery and maintain the DC bus voltage not exceeding the second voltage U2.

[0072] In one embodiment, in addition to energy recovery through mechanical energy, energy can also be recovered through the heat generated during vehicle operation.

[0073] Specifically, the vehicle system further includes: a thermoelectric coupling energy recovery module. The thermoelectric coupling energy recovery module includes: a phase change material coating, a thermoelectric generator, and a heat sink; the phase change material coating is coated on the surface of the motor and / or the surface of the motor, and the thermoelectric generators are distributed in an array and cover the preset heating area.

[0074] Among them, the phase change material coating can be obtained from a phase change material (PCM). For example, it can be paraffin or composite salt. It is coated on high-heat-generating components such as the boom hydraulic motor, generator, swing hydraulic motor, and low-speed high-torque motor. The phase change material coating can absorb and store waste heat through phase change (the transformation between solid and liquid states). The coating thickness of the phase change material coating can be designed according to the component heat load (for example, set to 1 - 3 mm) to ensure that the phase change endotherm is triggered when the hydraulic oil temperature rises above 80°C.

[0075] A thermoelectric generator (TEG) is a device that directly converts thermal energy into electrical energy using the temperature difference. Multiple groups of thermoelectric materials (such as bismuth telluride-based thermoelectric generators) are installed outside the phase change material coating. It uses the waste heat absorbed by the phase change material coating to form a temperature difference with the external environment (such as a heat sink), and directly converts thermal energy into direct current through the Seebeck effect.

[0076] The thermoelectric generators are distributed in an array form to cover a preset heat-generating area (such as the hydraulic pump outlet pipeline) to achieve efficient energy conversion.

[0077] However, for energy conversion through thermal energy, it is not applicable to all scenarios. In some scenarios, the energy recovery effect it may bring is not obvious, while in other scenarios, it is particularly obvious.

[0078] Based on this, according to the recent work records of the electric excavator and / or the current working environment, a preset thermal-electric coupling scenario is determined. In this preset thermal-electric coupling scenario, energy recovery is carried out through a thermal-electric coupling energy recovery module to charge the battery module.

[0079] For example, according to the recent work records of the electric excavator (referring to the work records within a recent preset time period, such as the work records within 10 minutes), it is determined that there are frequent starts and stops, or continuous high-load operation. At this time, the hydraulic system temperature is relatively high or fluctuates greatly, which is suitable for energy recovery of thermal energy. And the recent work records can be judged regularly. When the preset requirements are not met, the energy recovery through thermal energy can be stopped.

[0080] Also, for example, according to the current working environment, it is determined that the current environment is a high-temperature environment, or a noise-sensitive environment. The efficiency of the traditional cooling system is not sufficient to support heat dissipation, or the traditional cooling system cannot be turned on to the maximum power due to noise control, resulting in a relatively high temperature of the hydraulic system, which is also suitable for energy recovery of thermal energy.

[0081] During the energy recovery process, through the phase change material coating, the heat generated during the operation of the motor and / or the motor is absorbed. Through the thermoelectric generator and the heat sink, the heat absorbed by the phase change material coating is converted into direct current power (usually low-voltage direct current at this time, for example, 12~24V); through the boost DC-DC converter, the direct current power converted by the thermoelectric generator is boosted to obtain the fourth voltage U4 (which can reach a relatively high voltage at this time, for example, 400V).

[0082] Furthermore, when the fourth voltage U4 is set, the voltage control strategy also needs to be adjusted accordingly. Of course, the voltage control strategy based on the characteristics of the bidirectional DC-DC converter does not need to be adjusted, that is, the second voltage is greater than the third voltage. When implementing the energy recovery strategy, it is necessary to set the DC bus voltage greater than the second voltage.

[0083] When the power supply mode is grid combined with battery power supply, the voltage control strategy includes: For the first preset state of charge interval, the first voltage U1 is greater than the fourth voltage U4, and the fourth voltage U4 is greater than the second voltage U2; for the second preset state of charge interval, the second voltage U2 is greater than the fourth voltage U4, and the fourth voltage U4 is greater than the first voltage U1, and the first voltage U1 is greater than the third voltage U3; for the third preset state of charge interval, the third voltage U3 is greater than the fourth voltage U4, and the fourth voltage U4 is greater than the first voltage U1.

[0084] The overall adjustment idea is that in the first preset state of charge interval with a low state of charge, the grid module U1 dominates the power supply and charges the battery module. U4 needs to be higher than U2 corresponding to the battery module to give priority to using heat energy recovery for charging, and at the same time lower than U1 to avoid competing with the grid module.

[0085] In the second preset state of charge interval with a medium state of charge, U2 and U1 supply power cooperatively, and U4 is between the two, which can both support charging the battery module (that is, U4>U1) and assist the grid in power supply (that is, U4<U2).

[0086] In the third preset state of charge interval with a high state of charge, U3 corresponding to the battery module dominates the power supply, and U4 needs to be higher than U1 corresponding to the grid module to ensure that the TEG electric energy is preferentially charged or directly supplied.

[0087] As Figure 3 shown, the embodiment of the present application also provides an energy management device for an electric excavator, including: At least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions executable by the at least one processor. The instructions are executed by the at least one processor to enable the at least one processor to execute the energy management method for an electric excavator as described in the above embodiments.

[0088] An embodiment of the present application also provides a non-volatile computer storage medium storing computer-executable instructions, and the computer-executable instructions are configured as: the energy management method for an electric excavator as described in the above embodiments.

[0089] The embodiments in the present application are all described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the device and medium embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and for the relevant parts, reference can be made to the partial description of the method embodiments.

[0090] The device and medium provided by the embodiments of the present application correspond one by one to the method. Therefore, the device and medium also have beneficial technical effects similar to those of the corresponding method. Since the beneficial technical effects of the method have been described in detail above, the beneficial technical effects of the device and medium will not be elaborated here.

[0091] The above description is only for the embodiments of the present application and is not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. An energy management method for an electric excavator, characterized in that: include: Determining a power supply mode of a vehicle system of the electric excavator, and selecting a corresponding energy management strategy based on the power supply mode; Acquiring a state of charge of a battery module, and determining a preset charge interval hit in the energy management strategy according to the state of charge; Performing energy management on the electric excavator according to the sub-management strategy corresponding to the preset charge interval; The sub-management strategy includes an energy recovery strategy, which recovers energy through the arm energy recovery module and / or the rotation energy recovery module of the electric excavator to charge the battery module; In the energy recovery strategy, energy recovery is achieved by controlling the numerical relationship between the discharge voltage of the power grid module, the charging voltage of the battery module, the discharge voltage of the battery module, and the DC bus voltage.

2. The energy management method for an electric excavator according to claim 1, characterized in that: When the power supply mode is battery power supply alone, energy management is performed on the electric excavator according to the sub-management strategy corresponding to the preset charge interval, specifically including: A low battery alarm is issued for the lowest first preset charge interval; For a second preset charge interval higher than the first preset charge interval, the energy recovery strategy is executed while the vehicle system is powered by the battery module; For a third preset charge interval higher than the second preset charge interval, the vehicle system is powered by the battery module.

3. The energy management method for an electric excavator according to claim 1, characterized in that: When the power supply mode is the power grid combined with the battery, the energy management of the electric excavator is performed according to the sub-management strategy corresponding to the preset charge interval, specifically including: For a first lowest preset charge interval, the vehicle system is powered by the power grid module, the battery module is charged by the power grid module, and the energy recovery strategy is executed; For a second preset charge interval higher than the first preset charge interval, the energy recovery strategy is executed while powering the vehicle system through the power grid module and the battery module; For a third preset charge interval higher than the second preset charge interval, the vehicle system is powered by the battery module and the energy recovery strategy is executed.

4. The energy management method for an electric excavator according to claim 2 or 3, characterized in that: The vehicle system includes: a boom energy recovery module, a rotation energy recovery module, a hydraulic pump module, a battery module, and a power grid module; The arm energy recovery module is connected to the DC bus through a boost DC-DC converter, and transmits the electric energy obtained by energy recovery to the DC bus; The rotary energy recovery module is connected to the DC bus to transmit the electric energy obtained by energy recovery to the DC bus; The hydraulic pump module includes a motor controller and a hydraulic pump. The motor controller is connected to the DC bus. The motor controller drives the hydraulic pump to work by receiving electric energy transmitted by the DC bus. The battery module is connected to the DC bus through a bidirectional DC-DC converter, receives electric energy transmitted by the DC bus for charging, and transmits electric energy to the DC bus; The grid module is connected to the DC bus through a rectifier module to transmit electric energy to the DC bus.

5. The energy management method for an electric excavator according to claim 4, characterized in that: Define that the discharge voltage of the grid module through the rectifier module is a first voltage, the charging voltage of the battery module through the bidirectional DC-DC converter is a second voltage, and the discharge voltage of the battery module through the bidirectional DC-DC converter is a third voltage; When the power supply mode is battery power alone or grid power combined with battery power, the voltage control strategy includes: When the energy recovery strategy is executed, the DC bus voltage is greater than the second voltage; The second voltage is greater than the third voltage; When the power supply mode is grid-connected battery power supply, the voltage control strategy includes: For a first preset charging interval, the first voltage is greater than the second voltage; For a second preset charge interval, the second voltage is greater than the first voltage, and the first voltage is greater than the third voltage; For a third preset charge interval, the third voltage is greater than the first voltage.

6. The energy management method for an electric excavator according to claim 5, characterized in that: The boom energy recovery module includes: a proportional valve, a boom hydraulic motor, a generator, a rectifier bridge, and a boost DC-DC converter connected in sequence; The energy recovery is performed by the arm energy recovery module of the electric excavator to charge the battery module, specifically including: Acquire the opening of the boom lowering handle, and determine the opening of the control proportional valve according to the opening of the boom lowering handle; wherein the opening of the boom lowering handle is negatively correlated with the opening of the control proportional valve; The flow rate of the boom lowering high-pressure hydraulic oil flowing into the boom hydraulic motor is regulated by the proportional valve; The boom hydraulic motor drives the generator through high-pressure hydraulic oil; The mechanical energy is converted into AC electrical energy by the generator; The AC power is converted into DC power by the rectifier bridge; The DC power is boosted by the boost DC-DC converter, and the boosted DC power is transmitted to the DC bus.

7. The energy management method for an electric excavator according to claim 5, characterized in that: The rotary energy recovery module includes a rotary hydraulic motor and a low-speed high-torque motor; The energy recovery is performed by the rotary energy recovery module of the electric excavator to charge the battery module, specifically including: Get the opening of the rotary handle; When the opening of the rotary handle is greater than a preset rotary opening value, obtaining a rotary speed; When the rotation speed is lower than a preset speed, the rotation hydraulic motor and the low-speed high-torque motor are controlled to work; When the rotation speed is higher than a preset speed, the rotation hydraulic motor is controlled to be turned off, and the low-speed high-torque motor is controlled to work alone; When the swing handle opening is reduced to below the preset swing opening value, the swing hydraulic motor is controlled to be turned off, and the low-speed high-torque motor is controlled to slow down, so that the rotation energy is converted into electrical energy and transmitted to the DC bus.

8. The energy management method for an electric excavator according to claim 5, characterized in that: The vehicle system further includes: a thermal-electrically coupled energy recovery module; The thermal-electric coupling energy recovery module comprises: a phase change material coating, a thermoelectric power generation sheet, and a heat sink; the phase change material coating is coated on the surface of the motor and / or the motor surface, and the thermoelectric power generation sheet is distributed in an array and covers a preset heating area; The method further comprises: Determine triggering of a preset thermal-electric coupling scenario based on the recent working record of the electric excavator and / or the current working environment; The energy recovery is performed by a thermal-electric coupling energy recovery module to charge the battery module, specifically including: Absorbing the heat generated during the operation of the motor and / or motor through the phase change material coating; The heat absorbed by the phase change material coating is converted into direct current electricity through the thermoelectric power generation sheet and the heat sink; The DC power converted by the thermoelectric power generation sheet is boosted by a boost DC-DC converter to obtain a fourth voltage; When the power supply mode is grid-connected battery power supply, the voltage control strategy includes: For a first preset charging interval, the first voltage is greater than the fourth voltage, and the fourth voltage is greater than the second voltage; For a second preset charge interval, the second voltage is greater than the fourth voltage, the fourth voltage is greater than the first voltage, and the first voltage is greater than the third voltage; For a third preset charge interval, the third voltage is greater than the fourth voltage, and the fourth voltage is greater than the first voltage.

9. An energy management device for an electric excavator, characterized in that: include: at least one processor; as well as, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the energy management method for an electric excavator as described in claim 1.

10. A non-volatile computer storage medium storing computer executable instructions, characterized in that: The computer executable instructions are configured as: the energy management method for an electric excavator as described in claim 1.

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