Energy Management Method, Device and Medium for Electric Excavators

Abstract

The present application discloses an energy management method, device and medium for an electric excavator, relating to the field of energy recovery. The method includes: selecting a corresponding energy management strategy based on the power supply mode; obtaining the state of charge of the battery module, and determining a preset state-of-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 state-of-charge interval; the sub-management strategy includes an energy recovery strategy, and energy recovery is performed through the boom energy recovery module and / or the slewing energy recovery module of the electric excavator to charge the battery module. 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 braking kinetic energy of the slewing are converted into electric energy and stored in the battery module, reducing energy waste and improving the energy recovery efficiency.

Description

Technical Field

[0001] This application relates to the field of energy recovery, and particularly 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:

[0006] 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;

[0007] 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;

[0008] Perform energy management on the electric excavator according to the sub-management strategy corresponding to the preset state-of-charge interval;

[0009] 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;

[0010] 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.

[0011] 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:

[0012] For the lowest first preset state-of-charge interval, perform a low battery alarm;

[0013] 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;

[0014] For a third preset charge range higher than the second preset charge range, the vehicle system is powered by the battery module.

[0015] In one example, when the power supply mode is grid combined with battery power supply, energy management is performed on the electric excavator according to the sub-management strategy corresponding to the preset charge range, which specifically includes:

[0016] For the lowest first preset charge range, while the vehicle system is powered by the grid module, the battery module is charged by the grid module, and the energy recovery strategy is executed;

[0017] For a second preset charge range higher than the first preset charge range, while the vehicle system is powered by the grid module and the battery module, the energy recovery strategy is executed;

[0018] For a third preset charge range higher than the second preset charge range, the vehicle system is powered by the battery module, and the energy recovery strategy is executed.

[0019] 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;

[0020] The boom energy recovery module is connected to the DC bus through a boost DC-DC converter, and conveys the electric energy recovered to the DC bus;

[0021] The slewing energy recovery module is connected to the DC bus, and conveys the electric energy recovered to the DC bus;

[0022] 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;

[0023] 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 electric energy to the DC bus;

[0024] The grid module is connected to the DC bus through a rectification module, and conveys electric energy to the DC bus.

[0025] 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;

[0026] When the power supply mode is battery-only power supply or grid combined with battery power supply, the voltage control strategy includes:

[0027] When the energy recovery strategy is executed, the DC bus voltage is greater than the second voltage;

[0028] The second voltage is greater than the third voltage;

[0029] When the power supply mode is grid combined with battery power supply, the voltage control strategy includes:

[0030] For the first preset state of charge range, the first voltage is greater than the second voltage;

[0031] For the second preset charge range, the second voltage is greater than the first voltage, and the first voltage is greater than the third voltage;

[0032] For the third preset charge range, the third voltage is greater than the first voltage.

[0033] 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;

[0034] Performing energy recovery through the boom energy recovery module of the electric excavator to charge the battery module specifically includes:

[0035] Obtaining the opening degree of the boom lowering handle, and determining the control proportional valve opening degree according to the opening degree of the boom lowering handle; wherein, the opening degree of the boom lowering handle is negatively correlated with the control proportional valve opening degree;

[0036] Adjusting the flow rate of the high-pressure hydraulic oil for boom lowering flowing into the boom hydraulic motor through the proportional valve;

[0037] Driving the generator through the high-pressure hydraulic oil by the boom hydraulic motor;

[0038] Converting mechanical energy into AC electrical energy through the generator;

[0039] Converting AC electrical energy into DC electrical energy through the rectifier bridge;

[0040] Boosting the DC electrical energy through the boost DC-DC converter and delivering the boosted DC electrical energy to the DC bus.

[0041] In one example, the slewing energy recovery module includes a slewing hydraulic motor and a low-speed high-torque motor;

[0042] Performing energy recovery through the slewing energy recovery module of the electric excavator to charge the battery module specifically includes:

[0043] Obtain the opening degree of the slewing handle;

[0044] When the opening degree of the slewing handle is greater than the preset slewing opening degree value, obtain the slewing speed;

[0045] When the slewing speed is lower than the preset speed, control the slewing hydraulic motor and the low-speed high-torque motor to operate;

[0046] When the slewing speed is higher than the preset speed, control the slewing hydraulic motor to close and separately control the low-speed high-torque motor to operate;

[0047] When the opening degree of the slewing handle is reduced to be lower than the preset slewing opening degree value, control the slewing hydraulic motor to close and control the low-speed high-torque motor to decelerate, convert the slewing energy into electric energy, and transmit it to the DC bus.

[0048] In one example, the vehicle system further includes: a thermal-electric coupling energy recovery module;

[0049] The thermal-electric 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 a preset heat generation area;

[0050] The method further includes:

[0051] Determine to trigger a preset thermal-electric coupling scenario according to the recent working record of the electric excavator and / or the current working environment;

[0052] Perform energy recovery through the thermal-electric coupling energy recovery module and charge the battery module, specifically including:

[0053] Absorb the heat generated during the operation of the motor and / or the motor through the phase change material coating;

[0054] Convert the heat absorbed by the phase change material coating into DC power through the thermoelectric generator and the heat sink;

[0055] Boost the DC power converted by the thermoelectric generator through a boost DC-DC converter to obtain a fourth voltage;

[0056] When the power supply mode is grid-connected battery power supply, the voltage control strategy includes:

[0057] 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;

[0058] 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;

[0059] 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.

[0060] On the other hand, the present application also proposes an energy management device for an electric excavator, including:

[0061] At least one processor; and,

[0062] A memory communicatively connected to the at least one processor; wherein,

[0063] 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, for example, the energy management method for an electric excavator as described in the above example.

[0064] 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.

[0065] The energy management method for an electric excavator proposed by the present application can bring the following beneficial effects:

[0066] 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 braking kinetic energy of the slewing are converted into electric energy and stored in the battery module, reducing energy waste and improving the energy recovery efficiency.

[0067] 2. Based on the dynamic interval management strategy of the battery state of charge, different charge intervals are accurately matched to avoid overcharging and over-discharging of the battery, optimize the battery performance, and extend the battery life.

[0068] 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 reduce the long-term use cost of the electric excavator.

[0069] 4. Through efficient energy recovery and management, the waste of electric energy and battery loss are reduced, indirectly reducing carbon emissions and resource consumption, and improving the environmental protection benefits. Description of the Drawings

[0070] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The illustrative 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:

[0071] Figure 1 It is a schematic flowchart of the energy management method for an electric excavator in an embodiment of the present application;

[0072] Figure 2 It is a schematic diagram of the modules of a vehicle system in a certain situation in an embodiment of the present application;

[0073] Figure 3 It is a schematic diagram of the energy management device for an electric excavator in an embodiment of the present application. Detailed implementation manners

[0074] 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 the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0075] The technical solutions provided by the embodiments of the present application will be described in detail below in conjunction with the drawings.

[0076] As Figure 1 shown, an embodiment of the present application provides an energy management method for an electric excavator, including:

[0077] 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.

[0078] For an electric excavator, its power supply is mainly through an internal battery and / or an external power grid. In the embodiments of the present application, two power supply modes are mainly involved, namely, battery-only power supply and power grid combined with battery power supply. Of course, in actual work, other power supply modes can also be set, and corresponding energy management strategies can be set. For example, a power supply mode of power grid-only power supply can be set, or a power supply mode of multiple external power grids mixed power supply can be set, etc.

[0079] For different power supply modes, corresponding energy management strategies are respectively set. Through the energy management strategies, the energy management in the electric excavator is realized. For example, it includes charging management, discharging management of electric energy, and mutual conversion between electric energy and mechanical energy, etc.

[0080] 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.

[0081] 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.

[0082] In the energy management strategy, multiple preset charge intervals are set, and each preset charge interval has an upper limit and a lower limit value. The number of preset charge intervals and the upper and lower limit values can be set based on the actual situation.

[0083] S103: Perform energy management on the electric excavator according to the sub-management strategy corresponding to the preset charge interval.

[0084] Among them, the sub-management strategy includes an energy recovery strategy, and energy recovery is performed through the boom energy recovery module and / or the slewing energy recovery module of the electric excavator to charge the battery module;

[0085] 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.

[0086] In the energy management strategy, a corresponding strategy is set for each preset charge interval, and here the strategy corresponding to each preset charge interval is called the sub-management strategy.

[0087] In some sub-management strategies, there may be an energy recovery strategy. The energy recovery strategy refers to the process of converting the excess energy (such as kinetic energy, potential energy, etc.) generated during the operation of the energy recovery structure (such as including the boom energy recovery module, the slewing energy recovery module) set in the electric excavator into hydraulic energy, and then converting the hydraulic energy into electrical energy to achieve charging of the battery module.

[0088] 1. Through the synergistic effect of the boom energy recovery module and the slewing energy recovery module, convert the potential energy of the boom descending and the kinetic energy of slewing braking into electrical energy and store it in the battery module, reducing energy waste and improving energy recovery efficiency.

[0089] 2. Based on the dynamic interval management strategy of the battery state of charge, accurately match different charge intervals, avoid overcharging and over-discharging of the battery, optimize the battery usage performance, and extend the battery life.

[0090] 3. The energy recovery and dynamic management strategy work together to reduce the overall system energy consumption, reduce the dependence on external charging, and reduce the long-term use cost of the electric excavator.

[0091] 4. Through efficient energy recovery and management, reduce electrical energy waste and battery loss, indirectly reduce carbon emissions and resource consumption, and improve environmental protection benefits.

[0092] 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.

[0093] Among them, the boom energy recovery module is mainly used to utilize potential energy to recover energy and finally convert it into electric energy when the boom descends. It is connected to the DC bus through a boost DC-DC converter (boost DCDC), and conveys the electric energy obtained from energy recovery to the DC bus.

[0094] The slewing energy recovery module is mainly used to utilize kinetic energy to recover energy and finally convert it into electric energy when the electric excavator slews. It is connected to the DC bus and conveys the electric energy obtained from energy recovery to the DC bus.

[0095] 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 large pump) to work by receiving the electric energy conveyed by the DC bus. The hydraulic pump can drive the hydraulic motors in the boom and slewing device to work.

[0096] 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, and may also discharge while charging. Therefore, it may receive the electric energy conveyed by the DC bus for charging, and / or convey electric energy to the DC bus, that is, perform discharging.

[0097] The power grid module is connected to an external power grid and is connected to the DC bus through a rectifier module to convey electric energy to the DC bus.

[0098] For convenience of description, here it is defined that the discharging voltage of the power grid module through the rectifier module is the first voltage U1, the charging voltage of the battery module through the bidirectional DC-DC converter is the second voltage U2, the discharging voltage of the battery module through the bidirectional DC-DC converter is the third voltage U3, and the range of the state of charge is 0~100%.

[0099] Based on the characteristics of the bidirectional DC-DC converter, whether the power supply mode is battery-only power supply or power grid combined with 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 battery module.

[0100] In one embodiment, as Figure 2As shown in the figure, the boom energy recovery module includes the following components connected in sequence: a proportional valve (for regulating the flow rate of the high-pressure hydraulic oil for the boom to lower into the hydraulic motor), a boom hydraulic motor (for driving the 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).

[0101] When performing energy recovery, first 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; among them, the opening degree of the boom lowering handle is negatively correlated with the opening degree of the control proportional valve.

[0102] In actual work, the flow rate of the high-pressure hydraulic oil for the boom to lower into the boom hydraulic motor is regulated through the proportional valve; the boom hydraulic motor is driven by the high-pressure hydraulic oil to drive the generator; the mechanical energy is converted into alternating current energy through the generator; the alternating current energy is converted into direct current energy through the rectifier bridge; the boost DC-DC converter boosts the direct current energy and conveys the boosted direct current energy to the DC bus.

[0103] For example, define the opening degree range of the boom lowering handle as 0~100%. When the opening degree of the boom lowering handle is less than the first preset lowering opening degree value, it is considered that the required boom lowering speed is relatively small at this time, and the opening degree of the control proportional valve can be directly set to a relatively high value (for example, 90%~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 conveying it to the DC bus.

[0104] When the opening degree of the boom lowering handle is greater than the first preset lowering opening degree value and less than the second preset lowering opening degree value (which is higher than the first preset lowering opening degree value), in this working condition, while considering the required boom lowering speed, energy recovery is also taken into account. The relatively high value of the opening degree of the proportional valve is reduced to a preset value Q. Part of the boom lowering hydraulic oil returns to the fuel tank through the original vehicle oil circuit to ensure the boom lowering speed, and at the same time, the remaining part of the boom lowering hydraulic oil flows into the hydraulic motor to drive the generator to generate electricity.

[0105] When the opening degree of the boom lowering handle is greater than the second preset lowering opening degree value, the opening degree of the proportional valve can be further reduced, or the opening degree 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, part of the boom lowering energy can be recovered.

[0106] In one embodiment, as Figure 2As shown in the figure, the swing energy recovery module includes a swing hydraulic motor and a low-speed high-torque motor. Generally, there are multiple swing hydraulic motors in an electric excavator. Taking the example of including two swing hydraulic motors, one of the swing hydraulic motors can be replaced with a low-speed high-torque motor. In addition, before replacing the low-speed high-torque motor, the functional relationship between the swing handle opening of the double swing hydraulic motors of the electric excavator and the swing speed of the excavator can be calibrated to facilitate the subsequent acquisition of the swing speed.

[0107] Define the swing handle opening range from 0 to 100% and obtain the swing handle opening.

[0108] When the swing handle opening is less than the preset swing opening value, it is considered at this time that the electric excavator does not perform a swing action, and the system controls the swing hydraulic motor to work to maintain the non-rotation action of the excavator.

[0109] When the swing handle opening is greater than the preset swing opening value, obtain the swing speed. It can be obtained through the functional relationship calibrated above, or can be obtained in real time by installing a sensor.

[0110] When the swing speed is lower than the preset speed V1, this stage is defined as the swing start-up stage of the excavator. The starting torque required in this stage is relatively large. Control the swing hydraulic motor and the low-speed high-torque motor to work, set the target speed to V1, and make the swing speed quickly reach V1.

[0111] When the swing speed is higher than the preset speed, it is considered that the swing start-up stage is completed and the excavator enters the rotation stage. The rotation torque required in this stage is less than the swing starting torque. Control the swing hydraulic motor to close and control the low-speed high-torque motor to work alone.

[0112] When the swing handle opening starts to decrease from large to small until it decreases to less than the preset opening value (even reset to 0), this stage is defined as the swing deceleration and stop stage. Still control the swing hydraulic motor to close and control the low-speed high-torque motor to decelerate, convert the swing energy into electrical energy, and transmit it to the DC bus. Among them, the maximum energy recovery is the goal of this energy recovery, and there is no recovery current limit. The maximum current and voltage of the motor controller are used as the goal for braking energy feedback to achieve the maximum energy recovery.

[0113] 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 a first preset state-of-charge interval, a second preset state-of-charge interval, and a third preset state-of-charge interval in sequence.

[0114] 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 that it hits the lowest first preset state-of-charge interval. At this time, a low-battery alarm is given.

[0115] When the state of charge is higher than value A and lower than 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 charge interval. While supplying power to the vehicle system through the battery module, an energy recovery strategy is executed. The system controls the bidirectional DC-DC converter to discharge at the third voltage U3, thereby supplying 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, realizing energy recovery and maintaining the DC bus voltage not exceeding the second voltage U2.

[0116] When the state of charge is higher than value B, it is considered to hit the third preset charge interval higher than the second preset charge interval. At this time, it is considered that the battery is fully charged and no energy recovery is required. In this state, the vehicle system shuts down the boom energy recovery module and the slewing energy recovery module, and continues to supply power to the vehicle system through the battery module.

[0117] 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 in-vehicle battery module can also supply power to the vehicle system, realizing the hybrid energy power supply of the electric excavator. The energy management strategy of grid-connected battery power supply can be set as follows: from low to high state of charge, there are a first preset charge interval, a second preset charge interval, and a third preset charge interval in sequence.

[0118] It should be noted here that in the case of battery-only power supply and grid-connected battery power supply, the upper limit values and lower limit values of the first preset charge interval, the second preset charge interval, and the third preset charge interval can be the same, or can be set to different values based on requirements. Of course, more or fewer preset charge intervals can also be set based on requirements in the energy management strategies of various power supply modes.

[0119] For the convenience of description, the upper limit values and lower limit values of both are described as being the same here.

[0120] When the state of charge is lower than value A, it is considered to hit the lowest first preset charge interval. In this state, the battery has a low charge, and it is necessary to charge the battery module while also meeting the motor's power consumption requirements. Therefore, while supplying power to the vehicle system through the grid module, the grid module charges the battery module, and an energy recovery strategy is executed.

[0121] Based on this, the charging voltage U2 of the bi-directional DC-DC converter for the battery module can be set to be less than the DC output voltage U1 of the rectifier module by a certain value (that is, the voltage control strategy is set such that the first voltage is greater than the second voltage). In this state, the DC output voltage U1 of the rectifier module can not only charge the battery module through the bi-directional 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 bi-directional DC-DC converter to charge the battery module to achieve energy recovery.

[0122] When the state of charge is higher than value A and lower than value B, it is considered to hit the second preset charge interval higher than the first preset charge interval. In this state, it is considered that the battery power is not low, and there is no need to charge the battery module with the direct current output by the rectifier module of the power grid module. The battery charging only needs to receive the electrical energy recovered by the boom energy recovery module and / or the slewing energy recovery module. That is, while supplying power to the vehicle system through the power grid module and the battery module, the energy recovery strategy is executed.

[0123] Based on this, the charging voltage U2 of the bi-directional DC-DC converter for the battery module is set to be greater than the DC output voltage U1 of the rectifier module by a certain value (that is, the voltage control strategy is set such that the second voltage is greater than the first voltage), and the discharge voltage U3 of the battery module after passing through the bi-directional DC-DC converter is set to be less than U1 by a certain value (that is, the voltage control strategy is set such that the first voltage is greater than the third voltage).

[0124] Since the second voltage is greater than the first voltage, the first voltage U1 output by the rectifier 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-duty work, the first voltage output by the rectifier module of the power grid module is unstable, and the first voltage U1 drops significantly instantaneously, resulting in an overcurrent problem in the vehicle system.

[0125] When the electric excavator is performing heavy-duty 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 bi-directional DC-DC converter to make up for the power grid module fluctuations, so that the DC bus voltage of the vehicle system is not lower than the third voltage U3, thus solving the above problem.

[0126] 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 bi-directional DC-DC converter to charge the battery module to achieve energy recovery and maintain the DC bus voltage not exceeding the second voltage U2.

[0127] When the state of charge is higher than the B value, it is considered to hit 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 rectifier module of the 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 comes entirely from the battery module and does not require the electrical energy of the 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.

[0128] In one embodiment, in addition to recovering energy through mechanical energy, energy can also be recovered through the heat generated during vehicle operation.

[0129] 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; the thermoelectric generators are distributed in an array and cover a preset heating area.

[0130] Among them, the phase change material coating can be obtained by a phase change material (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, slewing hydraulic motor, and low-speed high-torque motor. The phase change material coating can absorb and store waste heat through a phase change (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.

[0131] A thermoelectric generator (TEG) is a device that directly converts thermal energy into electrical energy using a temperature difference. Multiple groups of thermoelectric materials (for example, 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 (for example, the heat sink) and directly converts thermal energy into direct current through the Seebeck effect.

[0132] The thermoelectric generators are distributed in an array form and cover a preset heating area (for example, the hydraulic pump outlet pipeline) to achieve efficient energy conversion.

[0133] 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.

[0134] Based on this, according to the recent working 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.

[0135] For example, according to the recent working records of the electric excavator (referring to the working records within a recent preset time period, such as the working records within 10 minutes), it is determined that frequent start-stop is required, or continuous high-load operation is maintained. At this time, the temperature of the hydraulic system is relatively high or fluctuates greatly, and it is suitable for energy recovery of thermal energy. And the recent working records can be judged regularly. When the preset requirements are not met, the energy recovery through thermal energy can be stopped.

[0136] 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 insufficient 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. Similarly, it is suitable for energy recovery of thermal energy.

[0137] During the energy recovery process, heat generated during the operation of the motor and / or the motor is absorbed through a phase change material coating, and the heat absorbed by the phase change material coating is converted into direct current power (usually low-voltage direct current at this time, such as 12 - 24V) through a thermoelectric generator and a heat sink; the direct current power converted by the thermoelectric generator is boosted through a boost DC-DC converter to obtain a fourth voltage U4 (which can reach a relatively high voltage at this time, such as 400V).

[0138] 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.

[0139] When the power supply mode is grid combined with battery power supply, the voltage control strategy includes:

[0140] For the first preset charge range, 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 charge range, the second voltage U2 is greater than the fourth voltage U4, 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 charge range, the third voltage U3 is greater than the fourth voltage U4, and the fourth voltage U4 is greater than the first voltage U1.

[0141] The overall adjustment idea is that in the first preset charge range of the low charge state, 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 be lower than U1 to avoid competing with the grid module.

[0142] In the second preset charge range of the medium charge state, 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).

[0143] In the third preset charge range of the high charge state, 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.

[0144] As Figure 3 shown, the embodiment of the present application also provides an energy management device for an electric excavator, including:

[0145] At least one processor; and,

[0146] A memory communicatively connected to the at least one processor; wherein,

[0147] The memory stores instructions executable 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, such as: the energy management method for an electric excavator described in the above embodiment.

[0148] The embodiment of the present application also provides a non - volatile computer storage medium, storing computer - executable instructions, and the computer - executable instructions are set as: the energy management method for an electric excavator described in the above embodiment.

[0149] Each embodiment in the present application is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and 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 the relevant parts can refer to the partial description of the method embodiments.

[0150] The device, medium, and method provided by the embodiments of the present application correspond one by one. 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.

[0151] The above are only the embodiments of the present application and are 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, 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 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 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 the 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; 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; 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 conveys the electric energy to the DC bus; The power grid module is connected to the DC bus through a rectification module, and conveys the electric energy to the DC bus; Define the discharge voltage of the power grid module through the rectification module as the first voltage, the charging voltage of the battery module through the bidirectional DC-DC converter as the second voltage, and the discharge voltage of the battery module through the bidirectional DC-DC converter as the third voltage; When the power supply mode is battery-only power supply or power grid combined with battery power supply, the voltage control strategy includes: When executing the energy recovery strategy, 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 power grid combined with battery power supply, the voltage control strategy includes: For the first preset charge interval, the first voltage is greater than the second voltage; For the second preset charge interval, the second 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 first voltage.

2. The energy management method for an electric excavator according to claim 1, wherein, When the power supply mode is battery-only power supply, perform energy management on the electric excavator according to the sub-management strategy corresponding to the preset charge interval, specifically including: For the lowest first preset charge interval, perform a low battery alarm; For the second preset charge interval higher than the first preset charge interval, while the battery module supplies power to the vehicle system, execute the energy recovery strategy; For the third preset charge interval higher than the second preset charge interval, the battery module supplies power to the vehicle system.

3. The energy management method for an electric excavator according to claim 1, characterized in that 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, which specifically includes: 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.

4. The energy management method for an electric excavator according to claim 1, characterized in that 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 convey the boosted DC electrical energy to the DC bus.

5. The energy management method for an electric excavator according to claim 1, characterized in that 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 the preset slewing opening value, obtain the slewing speed; When the slewing speed is lower than the preset speed, control the slewing hydraulic motor and the low-speed high-torque motor to work; When the slewing speed is higher than the preset speed, control the slewing hydraulic motor to close, and separately control the low-speed high-torque motor to work; 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 convey it to the DC bus.

6. The energy management method for an electric excavator according to claim 1, characterized in that, 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 a preset heating area; The method further includes: Determine to trigger a preset thermoelectric coupling scenario according to the recent work record of the electric excavator and / or the current working environment; Energy recovery is performed through the thermoelectric coupling energy recovery module to charge the battery module, which specifically includes: Absorb the heat generated during the operation of the motor and / or the engine through the phase change material coating; Convert the heat absorbed by the phase change material coating into DC power through the thermoelectric generator and the heat sink; Boost the DC power converted by the thermoelectric generator 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 range, the first voltage is greater than the fourth voltage, and the fourth voltage is greater than the second voltage; For the second preset charge range, 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 range, the third voltage is greater than the fourth voltage, and the fourth voltage is greater than the first voltage.

7. An energy management device for an electric excavator, characterized in that, Comprising: 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 to enable the at least one processor to execute the energy management method for an electric excavator as claimed in claim 1.

8. A non-volatile computer storage medium stores computer-executable instructions, characterized in that, The computer-executable instructions are set to be the energy management method for an electric excavator as claimed in claim 1.

Images