Method and device for flow demand control for electrically powered construction machines

Abstract

The application discloses a flow demand control method and equipment for an electric engineering machine, and the method comprises the following steps: determining a pilot handle opening value according to a pilot handle opening voltage value; obtaining a hydraulic oil demand flow value according to the pilot handle opening value and a preset hydraulic oil demand response characteristic value; acquiring a main pump pressure value, and dynamically correcting the hydraulic oil demand flow value according to the main pump pressure value to obtain a corrected flow value; and adjusting the current of a first proportional valve according to the corrected flow value to control the opening value of the first proportional valve. The flow demand is corrected in real time by the main pump pressure, high-pressure working conditions are prevented from over-power output, the overflow frequency is reduced, and dynamic pressure correction is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flow control, in particular to a flow demand control method and device for electric engineering machinery. BACKGROUND

[0002] In the field of modern engineering machinery, fuel engineering machinery has a large oil consumption and causes serious environmental pollution. Electric engineering machinery (such as electric excavators, electric loaders, electric forklifts, etc.) gradually attracts attention due to its advantages of high efficiency and environmental protection.

[0003] However, the traditional scheme has the following disadvantages:

[0004] 1. Open-loop control, relying on experience calibration: the traditional scheme controls the flow by a fixed curve (such as a handle opening-flow linear mapping), which is easy to cause flow over-limit in high-pressure working conditions, and thus causes overflow or power overload.

[0005] 2. Static response characteristics: the fixed slope flow response curve is difficult to adapt to different working scenarios (such as low sensitivity for fine operation and high response for heavy load), and the control flexibility is poor.

[0006] 3. Lack of pressure coupling protection: the main pump pressure is not monitored in real time, and the risk of motor overload or overflow is high, especially the short-time overload capacity of the motor after oil-to-electricity conversion easily causes damage to the hydraulic pump due to over-power. SUMMARY

[0007] To solve the above problems, the present application provides a flow demand control method for electric engineering machinery, comprising:

[0008] determining a pilot handle opening value according to a pilot handle opening voltage value;

[0009] obtaining a hydraulic oil demand flow value according to the pilot handle opening value and a preset hydraulic oil demand response characteristic value;

[0010] obtaining a main pump pressure value, and dynamically correcting the hydraulic oil demand flow value according to the main pump pressure value to obtain a corrected flow value;

[0011] adjusting the current of the first proportional valve according to the corrected flow value to control the opening value of the first proportional valve.

[0012] In one example, the pilot handle opening value is determined according to the pilot handle opening voltage value, specifically comprising:

[0013] determining a voltage output range of the pilot handle opening voltage value, and setting a plurality of voltage output intervals according to the voltage output range;

[0014] If the pilot handle opening degree voltage value hits the voltage output interval at two ends, it is determined that the pilot handle opening degree value is a fixed value corresponding to the voltage output interval;

[0015] If the pilot handle opening degree voltage value hits the voltage output interval in the middle, the corresponding pilot handle opening degree value is determined based on the percentage position of the pilot handle opening degree voltage value in the voltage output interval.

[0016] In one example, according to the pilot handle opening degree value and a preset hydraulic oil demand response characteristic value, a hydraulic oil demand flow value is obtained, specifically including:

[0017] A preset calibration opening degree value and a hydraulic oil demand response characteristic value are determined, wherein the hydraulic oil demand response characteristic value is positively correlated with the hydraulic oil control response condition;

[0018] When the pilot handle opening degree value is lower than the calibration opening degree value, the hydraulic oil demand response characteristic value is taken as the K value according to the minimum value of the hydraulic oil demand flow value, and a first linear relationship is generated;

[0019] According to the first linear relationship, the hydraulic oil demand flow value corresponding to the calibration opening degree value is determined;

[0020] When the pilot handle opening degree value is higher than the calibration opening degree value, a second linear relationship is generated according to the specified flow value and the maximum value of the hydraulic oil demand flow value.

[0021] In one example, the hydraulic oil demand flow value is dynamically corrected according to the main pump pressure value to obtain a corrected flow value, specifically including:

[0022] According to the main pump maximum output flow and the main pump maximum absorption power, a main pump turning pressure value is determined, and a preset overflow protection pressure value and a calibration pressure value lower than the overflow protection pressure value are determined;

[0023] When the main pump pressure value is less than the main pump turning pressure value, the hydraulic oil demand flow value is directly taken as the corrected flow value;

[0024] When the main pump pressure value is greater than the main pump turning pressure value and lower than the calibration pressure value, a corrected flow value is calculated according to the main pump pressure value and the main pump maximum absorption power;

[0025] When the main pump pressure value is greater than the calibration pressure value, the main pump pressure value is adjusted to be lower than the overflow protection pressure value.

[0026] In one example, the method further includes:

[0027] By pre-setting a plurality of pressure sensors, corresponding main pump pressure values are obtained respectively;

[0028] Based on the setting position of the pressure sensor, a dynamic weight factor of the pressure sensor is determined;

[0029] When there is at least one pressure sensor corresponding to the main pump pressure value greater than the main pump turning pressure value or the calibration pressure value, the first weight factor and the second weight factor are used to weight and sum all the main pump pressure values corresponding to the pressure sensors respectively, to obtain a comprehensive main pump pressure value, and the comprehensive main pump pressure value is used to determine whether the main pump pressure value reaches the main pump turning pressure value or the calibration pressure value;

[0030] Among them, the second weight factor has a lower discrete degree of dynamic weight factors between different pressure sensors than the first weight factor.

[0031] In one example, according to the modified flow value, the current of the first proportional valve is adjusted to control the opening value of the first proportional valve, specifically including:

[0032] The positive terminal of the coil of the first proportional valve is connected to the output terminal of the high-side drive chip, and the high-side drive of the electromagnetic valve is realized through the high-side drive chip;

[0033] After the negative terminal of the coil of the first proportional valve is connected to the current sampling resistor, the low-side drive of the electromagnetic valve is realized through the low-side drive MOS tube; wherein the control of the MOS tube is realized through the low-side drive chip.

[0034] In one example, the method further comprises:

[0035] The hydraulic pump module to which the first proportional valve belongs is determined, and the vehicle system to which the hydraulic pump module belongs is determined; wherein the vehicle system includes: a large arm energy recovery module, a swing energy recovery module, a hydraulic pump module, a battery module, a power grid module, and a direct current bus;

[0036] The large arm energy recovery module is connected to the direct current bus through a boost DC-DC converter, and the electrical energy recovered by the large arm energy recovery module is transmitted to the direct current bus;

[0037] The swing energy recovery module is connected to the direct current bus, and the electrical energy recovered by the swing energy recovery module is transmitted to the direct current bus;

[0038] The hydraulic pump module is connected to the direct current bus, and the electrical energy transmitted by the direct current bus is received to drive the hydraulic pump to work;

[0039] The battery module is connected with the DC bus through a bidirectional DC-DC converter, receives electric energy transmitted by the DC bus for charging, and / or transmits electric energy to the DC bus.

[0040] The grid module is connected with the DC bus through a rectifier module, and transmits electric energy to the DC bus.

[0041] In one example, the boom energy recovery module comprises, in sequence: a second proportional valve, a boom hydraulic motor, a generator, a rectifier bridge, and a step-up DC-DC converter.

[0042] The energy recovery process of the swing energy recovery module comprises:

[0043] An opening degree of a boom lowering handle is obtained, and a control proportional valve opening degree is determined according to the boom lowering handle opening degree; wherein the boom lowering handle opening degree is negatively correlated with the control proportional valve opening degree.

[0044] The flow of the boom lowering high-pressure hydraulic oil flowing into the boom hydraulic motor is adjusted through the second proportional valve.

[0045] The boom hydraulic motor is driven by the high-pressure hydraulic oil to drive the generator.

[0046] The generator converts mechanical energy into alternating current energy.

[0047] The rectifier bridge converts the alternating current energy into direct current energy.

[0048] The step-up DC-DC converter steps up the direct current energy, and transmits the stepped-up direct current energy to the DC bus.

[0049] In one example, the swing energy recovery module comprises a swing hydraulic motor and a low-speed large-torque motor.

[0050] The energy recovery process of the swing energy recovery module comprises:

[0051] An opening degree of a swing handle is obtained.

[0052] When the swing handle opening degree is greater than a preset swing opening degree value, a swing speed is obtained.

[0053] When the swing speed is lower than a preset speed, the swing hydraulic motor and the low-speed large-torque motor are controlled to work.

[0054] When the swing speed is higher than the preset speed, the swing hydraulic motor is controlled to be closed, and the low-speed large-torque motor is controlled to work alone.

[0055] When the swing handle opening degree is reduced to be lower than the preset swing opening degree value, the swing hydraulic motor is controlled to be closed, and the low-speed large-torque motor is controlled to be reduced in speed, swing energy is converted into electric energy, and the electric energy is delivered to a direct current bus.

[0056] In another aspect, the application further provides a flow demand control device for an electric engineering machinery, comprising:

[0057] at least one processor; and,

[0058] a memory in communication connection with the at least one processor; wherein,

[0059] 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 perform the flow demand control method for the electric engineering machinery according to any one of the above examples.

[0060] In another aspect, the application further provides a non-volatile computer storage medium storing computer executable instructions, and the computer executable instructions are configured to perform the flow demand control method for the electric engineering machinery according to any one of the above examples.

[0061] The flow demand control method for the electric engineering machinery provided by the application can bring the following beneficial effects:

[0062] 1. The flow demand is corrected in real time by the main pump pressure, the over-power output in high-pressure working conditions is avoided, the overflow frequency is reduced, and dynamic pressure correction is realized.

[0063] 2. The preset hydraulic oil demand response characteristic value is supported, different scene sensitivity adjustment is supported, control adaptability is improved, and adjustable response characteristics are realized.

[0064] 3. The handle opening degree is coupled with the pressure, the operation intention is preferentially responded, the system safety is guaranteed, man-machine collaborative optimization is realized, and the operation efficiency and reliability are improved. BRIEF DESCRIPTION OF DRAWINGS

[0065] The accompanying drawings, which are included to provide a further understanding of the application, constitute a part of the application and illustrate the illustrative embodiments of the application and its description, and do not constitute an improper limitation of the application. In the drawings:

[0066] Figure 1 is a flowchart of the flow demand control method for the electric engineering machinery in the embodiments of the application;

[0067] Figure 2 is a hydraulic oil response characteristic diagram under one condition in the embodiments of the application;

[0068] Figure 3For one case in the embodiment of the present application, the maximum flow safety output range graph;

[0069] Figure 4 For one case in the embodiment of the present application, the proportional electromagnetic valve driving circuit diagram;

[0070] Figure 5 For one case in the embodiment of the present application, the module schematic diagram of the vehicle system;

[0071] Figure 6 For one case in the embodiment of the present application, the structure schematic diagram of the rectifier module;

[0072] Figure 7 For one case in the embodiment of the present application, the flow demand control device for the electric engineering machinery. DETAILED DESCRIPTION

[0073] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described below in detail with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0074] The technical solutions provided by the embodiments of the present application will be described in detail below with the drawings.

[0075] As shown in the drawings, the embodiments of the present application provide a flow demand control method for electric engineering machinery, which comprises: Figure 1

[0076] S101: Determine the pilot handle opening value according to the pilot handle opening voltage value.

[0077] Specifically, in the embodiments of the present application, the electric engineering machinery is taken as an example of an electric excavator. The voltage output range of the pilot handle opening voltage value is determined, and multiple voltage output intervals are set according to the voltage output range. Here, the voltage output range is V1-V2, at this time, three voltage output intervals can be set.

[0078] If the pilot handle opening voltage value hits the voltage output interval at both ends, the pilot handle opening value is determined as the fixed value corresponding to the voltage output interval. For the voltage output interval at both ends, when the voltage output interval at the lower limit end, it can be considered that the purpose of the driver is not to operate the pilot handle, which is usually a false touch, so the fixed value can be 0, and when the voltage output interval at the upper limit end, it can be considered that the driver wants to operate the pilot handle at full power, so the fixed value can be 100%.

[0079] ​If the pilot handle opening degree voltage value hits the middle voltage output interval, the corresponding pilot handle opening degree value is determined based on the percentage position of the pilot handle opening degree voltage value in the voltage output interval, that is, the corresponding pilot handle opening degree value is determined according to the degree of operation of the driver.

[0080] For example, the threshold voltages of the pilot handle are respectively V L = V1+0.3 and V H = V2-0.3, and three voltage output ranges are set, which are 0~V L , V L ~V H , and V H ~100%.

[0081] The pilot handle opening degree percentage is P ed , and the current voltage value of the pilot handle is U. As shown in Formula One:

[0082]

[0083] S102: Obtain a hydraulic oil demand flow value according to the pilot handle opening degree value and a preset hydraulic oil demand response characteristic value.

[0084] Specifically, a preset calibration opening degree value and a hydraulic oil demand response characteristic value are determined, wherein the hydraulic oil demand response characteristic value is positively correlated with the hydraulic oil control response, that is, the better the hydraulic oil control response, the higher the hydraulic oil demand response characteristic value. The calibration opening degree value can be a fixed value, for example, it can be set to 60%.

[0085] When the pilot handle opening degree value is lower than the calibration opening degree value, the hydraulic oil demand response characteristic value is taken as the K value according to the minimum value of the hydraulic oil demand flow value, to generate a first linear relationship, at this time, it is in the low opening degree area, belonging to the linear fast response stage, the higher the pilot handle opening degree value, the higher the hydraulic oil demand flow value, and the rising speed is determined by the K value.

[0086] According to the first linear relationship, the hydraulic oil demand flow value corresponding to the specified flow value of the calibration opening degree value is determined. When the pilot handle opening degree value reaches the calibration opening degree value, it has entered the high opening degree area, if it continues to advance according to the rising speed of the K value, it may cause the final hydraulic oil demand flow value to be too high or too low, therefore, it needs to enter the gradual saturation control stage to ensure that when the pilot handle opening degree value P ed is 100%, no matter how the K value is taken, the hydraulic oil demand flow value Q1 can reach 100%.

[0087] Therefore, when the pilot handle opening value is higher than the calibration opening value, a second linear relationship is generated according to the specified flow value and the highest value of the hydraulic oil demand flow value, and the K value in this stage is different from the K value in the previous stage, so as to be able to ensure that the pilot handle opening value P ed When the pilot handle opening value is 100%, the hydraulic oil demand flow value Q1 can reach 100%.

[0088] As shown in Figure 2 , in order to describe the response degree of the vehicle system to the hydraulic oil flow demand, a hydraulic oil response characteristic diagram as shown in Figure 2 is generated in advance, and the slope K of the straight line formed by the demand flow percentage and the origin when the pilot handle opening is the calibration opening value (60%) is defined as the hydraulic oil demand response characteristic value. By changing the K value, different response conditions of hydraulic oil control are realized, and the larger the K value, the better the response.

[0089] At this time, the hydraulic oil demand flow percentage Q1 calculated according to the handle opening value and the hydraulic oil demand response characteristic value is as shown in Formula Two:

[0090]

[0091] S103: Obtain the main pump pressure value, and dynamically correct the hydraulic oil demand flow value according to the main pump pressure value to obtain a corrected flow value.

[0092] After the oil-powered engineering machinery is changed to electric engineering machinery, the absorption power of the general hydraulic pump is greater than the rated output power of the engine, and it is difficult to fully exert the capacity of the hydraulic pump. Moreover, the rated power of the motor matched by the oil-powered engineering machinery changed to electric engineering machinery is the same as that of the engine, but the motor can overload 2-3 times the rated power output. Under the condition of motor overload output, the engine output power will exceed the absorption power of the hydraulic pump, resulting in damage to the hydraulic pump.

[0093] Based on this, after the oil-powered engineering machinery is changed to electric engineering machinery to form electric engineering machinery, in order to protect the hydraulic pump and fully exert the power output capacity of the hydraulic pump, corresponding correction strategies are set based on different main pump pressure values. Within the corresponding pressure value range, the output power will not exceed the maximum absorption power of the pump, ensuring safety.

[0094] Specifically, according to the main pump maximum output flow Q max and the main pump maximum absorption power P max , the main pump turning pressure value P p is determined. Wherein,

[0095] The preset overflow protection pressure value P out and the calibration pressure value P1 lower than the overflow protection pressure value are determined.

[0096] At this time, as shown inFigure 3 The correction strategy includes:

[0097] When the main pump pressure value is less than the main pump turning point pressure value, the hydraulic oil demand flow value Q1 is directly used as the correction flow value, that is, Q1 is not corrected.

[0098] When the main pump pressure value is greater than the main pump turning point pressure value and less than the calibration pressure value, the constant power control mode is entered, and the correction flow value is calculated according to the main pump pressure value and the maximum absorption power of the main pump, to ensure that the power does not exceed the limit. Among them, the correction flow value can be the maximum absorption power of the main pump divided by the main pump pressure value.

[0099] When the main pump pressure value is greater than the calibration pressure value, the overflow protection mode is entered. Generally, the engineering machinery hydraulic system will be provided with an overflow valve, and when the main pump pressure value exceeds the set overflow pressure value, the overflow valve is opened, and a large amount of energy will be wasted in the overflow process.

[0100] Therefore, in order to exert the hydraulic system capacity while avoiding overflow, a pressure value P out slightly smaller than the opening pressure value of the overflow valve is selected as the overflow protection pressure value P out , and a pressure value P1 smaller than the overflow protection pressure value P out is designed as the calibration pressure value. P1 out <overflow valve opening pressure value.

[0101] When the main pump pressure value is greater than the calibration pressure value, the constant power control mode is exited and the overflow protection mode is entered, with the overflow protection pressure value P out as the control target, to adjust the main pump pressure value so that the main pump pressure value is lower than the overflow protection pressure value, so that the hydraulic system pressure does not exceed the overflow pressure, and the system power output is ensured.

[0102] Further, in actual working conditions, in order to ensure the stability of sensor data acquisition, multiple pressure sensors can be set at different positions to detect the main pump pressure value. For example, the main pump outlet end, the valve group inlet end, and the actuator end are set positions, and the pressure sensors at each set position acquire the corresponding main pump pressure value respectively.

[0103] At this time, based on the set position of the pressure sensor, the dynamic weight factor of the pressure sensor is determined. The weight factor can be set as a dynamic weight factor according to the actual situation. However, the weight factor still needs to be set with a corresponding size relationship, for example, the size of the weight factor from high to low is: the main pump outlet end, the valve group inlet end, and the actuator end, and the closer to the main pump, the higher the weight factor.

[0104] When the main pump pressure value corresponding to at least one pressure sensor is greater than the main pump turning pressure value or the calibration pressure value, it is considered that the flow value is likely to be corrected at present, however, in order to further determine whether it is caused by the detection abnormality of a certain pressure sensor, the main pump pressure values corresponding to all pressure sensors are weighted and summed to obtain a comprehensive main pump pressure value through a first weight factor (corresponding to the main pump pressure value greater than the main pump turning pressure value and less than the calibration pressure value) and a second weight factor (corresponding to the main pump pressure value greater than the calibration pressure value), and whether the main pump pressure value reaches the main pump turning pressure value or the calibration pressure value is determined through the comprehensive main pump pressure value. Through the judgment of the comprehensive pressure value, the misjudgment caused by the abnormality of a certain pressure sensor can be solved.

[0105] Among them, the case that the main pump pressure value is greater than the calibration pressure value is more serious than the case that the main pump pressure value is greater than the main pump turning pressure value, at this time, all sensors are simultaneously affected by the same physical phenomenon, which is easy to destroy the dynamic balance of the system, leading to more uniform pressure distribution, so the readings of the pressure sensors arranged at any position tend to be the same.

[0106] Therefore, the dispersion degree of the dynamic weight factors between different pressure sensors in the second weight factor is lower than that in the first weight factor. The lower dispersion degree means that the weights between the pressure sensors are closer, which is more consistent with the situation that the readings of the pressure sensors tend to be the same when the situation is serious. For example, in the first weight factor, the weight factors of the main pump outlet end, the valve group inlet end and the actuator end are 1.2, 1 and 0.8 respectively, while in the second weight factor, they are 1.1, 1 and 0.9 respectively.

[0107] S104: Adjust the current of the first proportional valve according to the corrected flow value to control the opening value of the first proportional valve.

[0108] Therefore, the calculation of the hydraulic oil demand flow value (i.e. the corrected flow value) coupled with the pilot handle opening value and the main pump pressure value has been realized, and the actual hydraulic oil output is realized by controlling the opening of the first proportional valve on the main pump, and the size of the first proportional valve opening is determined by the size of the electromagnetic coil current of the first proportional valve.

[0109] Therefore, as shown in Figure 4 , a high-low side controllable proportional solenoid valve driving circuit and a corresponding current control strategy are set.

[0110] Specifically, the positive terminal of the coil of the first proportional valve is connected to the output terminal of a high-side driving chip (BTS5215) in the BTS5215. Figure 4 ​

[0111] After determining that the negative terminal of the coil of the first proportional valve is connected to the current sampling resistor, the MOS transistor driven by the low side ( Figure 4 The FQD20N03 chip in the middle drives the low-side of the solenoid valve; the control of the MOSFET is achieved through a low-side driver chip (FQD20N03). Figure 4 The implementation is based on the IR4427S.

[0112] In one embodiment, the first proportional valve belongs to the hydraulic pump module, which is a module within the vehicle system. When the first proportional valve controls the main pump (e.g., ...), ... Figure 5 The hydraulic pump shown can output a corresponding flow rate and then control other modules of the vehicle system to perform corresponding mechanical work, such as controlling the boom movement and controlling the rotation.

[0113] However, in actual operation, since the working scenarios of construction machinery are usually industrial scenarios, involving frequent boom descent, slewing and braking, electric construction machinery consumes a lot of energy during operation, and a large amount of energy is wasted in the form of heat energy and mechanical energy.

[0114] Based on this, corresponding energy recovery modules (including boom energy recovery module and slewing energy recovery module) were set up. Through the synergistic effect of the energy recovery modules, the descent potential energy of the boom and the slewing braking kinetic energy are converted into electrical energy and stored in the battery module, reducing energy waste and improving energy recovery efficiency.

[0115] Specifically, such as Figure 5 As shown, the vehicle system includes: boom energy recovery module, slewing energy recovery module, hydraulic pump module, battery module, power grid module, and DC bus.

[0116] The boom energy recovery module is mainly used to recover energy and convert it into electrical energy when the boom is lowering. It is connected to the DC bus through a boost DC-DC converter (boost DC-DC converter) to transmit the recovered electrical energy to the DC bus.

[0117] The slewing energy recovery module is mainly used to recover energy from kinetic energy and convert it into electrical energy during the slewing of electric engineering machinery. It is connected to the DC bus and transmits the recovered electrical energy to the DC bus.

[0118] The hydraulic pump module is connected to the DC bus and drives the hydraulic pump by receiving electrical energy from the DC bus. The hydraulic pump can drive the hydraulic motors in the boom and slewing device.

[0119] The battery module is connected with the DC bus through a bidirectional DC-DC converter. In different power supply modes corresponding to different sub-management strategies, the battery module can perform charging action, discharging action, or both charging and discharging. Therefore, the battery module can receive electric energy from the DC bus for charging, and / or deliver electric energy to the DC bus for discharging.

[0120] The grid module is connected with an external power grid and is connected with the DC bus through a rectifier module to deliver electric energy to the DC bus.

[0121] Further, as shown in FIG. 6, the boom energy recovery module includes, in sequence, a second proportional valve (for adjusting the flow rate of the boom lowering high-pressure hydraulic oil flowing into the hydraulic motor), a boom hydraulic motor (for driving the generator using the high-pressure hydraulic oil), a generator (for converting the rotating 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 direct current obtained by rectification to the system charging voltage). Figure 5

[0122] In the energy recovery process, the boom lowering handle opening degree is first obtained, and the control second proportional valve opening degree is determined according to the boom lowering handle opening degree. The boom lowering handle opening degree and the control second proportional valve opening degree are negatively correlated.

[0123] In actual work, the flow rate of the boom lowering high-pressure hydraulic oil flowing into the boom hydraulic motor is adjusted by the second proportional valve. The generator is driven by the high-pressure hydraulic oil through the boom hydraulic motor. 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 direct current energy is boosted through the boost DC-DC converter, and the boosted direct current energy is delivered to the DC bus.

[0124] For example, the boom lowering handle opening degree range is defined as 0-100%. When the boom lowering handle opening degree is less than a first preset lowering opening degree value, it is considered that the required boom lowering speed is small, and the control second proportional valve opening degree can be directly set to a higher value (for example, 90%-100%). Most or all of the boom lowering hydraulic oil is discharged through the boom hydraulic motor, and the boom hydraulic motor drives the generator to generate electricity, thereby generating electric energy and delivering it to the DC bus.

[0125] ​When the boom lowering handle opening is greater than the first preset lowering opening value but less than the second preset lowering opening value (which is higher than the first preset lowering opening value), under this working condition, while considering the boom lowering speed requirement and energy recovery, the higher value of the second proportional valve opening setting is reduced to a preset value Q2. This allows some of the boom lowering hydraulic oil to return to the oil tank through the original vehicle oil circuit to ensure the boom lowering speed, while the remaining boom lowering hydraulic oil flows into the hydraulic motor to drive the generator to generate electricity.

[0126] When the boom lowering handle opening is greater than the second preset lowering opening value, the opening of the second proportional valve can be further reduced, or the opening of the second proportional valve can be kept constant at the Q2 value. This value can ensure the normal boom lowering speed, meet the operator's operation requirements, and at the same time, realize a portion of the boom lowering energy recovery.

[0127] like Figure 5 As shown, the slewing energy recovery module includes a slewing hydraulic motor and a low-speed, high-torque motor. Typically, electric construction machinery contains multiple slewing hydraulic motors; this example uses two slewing hydraulic motors, where one of them can be replaced with a low-speed, high-torque motor. Furthermore, before replacing the low-speed, high-torque motor, the functional relationship between the opening of the slewing handle of the two slewing hydraulic motors and the excavator's slewing speed can be calibrated to facilitate subsequent acquisition of the slewing speed.

[0128] Define the range of the rotary handle opening from 0 to 100%, and obtain the rotary handle opening.

[0129] When the opening of the slewing handle is less than the preset slewing opening value, it is assumed that the electric construction machinery will not perform a slewing action, and the system controls the slewing hydraulic motor to work to maintain the excavator from rotating.

[0130] When the opening of the slewing handle exceeds the preset slewing opening value, the slewing speed is obtained. This speed can be obtained through the function relationship calibrated above, or it can be obtained in real time by installing a sensor.

[0131] When the slewing speed is lower than the preset speed, this stage is defined as the excavator slewing start stage. The starting torque required in this stage is relatively large. The slewing hydraulic motor and low-speed high-torque motor are controlled to work, and the target speed is set to the preset speed so that the slewing speed can quickly reach the preset speed.

[0132] When the slewing speed is higher than the preset speed, the slewing start-up phase is considered complete, and the excavator enters the rotation phase. During this phase, the required rotation torque is less than the slewing start torque, so the slewing hydraulic motor is shut down, and the low-speed, high-torque motor is controlled to work independently.

[0133] When the swing handle opening degree starts to decrease from large to small until it is decreased below the preset opening degree value (even reset to 0), this stage is defined as the swing speed reduction and stop stage, the swing hydraulic motor is still controlled to be closed, and the low-speed large-torque motor is controlled to reduce the speed, the swing energy is converted into electric energy, and the electric energy is transmitted to the DC bus. Among them, the energy recovery this time is targeted at maximum energy recovery, without recovery current limitation, with the maximum current and voltage of the motor controller as the target for braking energy feedback, to achieve maximum energy recovery.

[0134] As shown in Figure 6 , the rectifier module includes: a short circuit protector, an AC contactor, an autotransformer, a rectifier bridge, a bus capacitor, a pre-charging unit, a temperature meter, a DC reactor, a DC fuse, and a start-stop switch.

[0135] The short circuit protector protects the vehicle system current, and when the system current exceeds the maximum system current, the system is powered off for protection; the AC contactor controls the power supply of the vehicle system in cooperation with the start and stop buttons; the autotransformer controls the step-up of the AC voltage, so that the voltage reaches the AC voltage required by the electric engineering machinery; the rectifier bridge converts high-voltage AC into high-voltage DC required by the electric engineering machinery; and the bus capacitor filters and stores energy for high-voltage DC.

[0136] The pre-charging unit includes a pre-charging resistor, a DC contactor, and a voltage meter. The pre-charging resistor is connected in series between the positive electrode of the rectifier bridge and the positive electrode of the bus capacitor. When the high-voltage electricity charges the bus capacitor through the pre-charging resistor, the voltage meter synchronously monitors the bus voltage. When the bus voltage exceeds the preset pre-charging end voltage, the DC contactor is controlled to be attracted, and the pre-charging process is completed.

[0137] The temperature meter monitors the temperature of the rectifier bridge. When the temperature of the rectifier bridge exceeds the preset high-temperature fault value, the normally closed relay is controlled to be opened, the AC contactor is disconnected, and the vehicle system is powered off; the DC reactor suppresses current fluctuations and protects the bus capacitor; the DC fuse provides overload and short circuit protection; and the start-stop switch controls the power supply by manual control.

[0138] As shown in Figure 7 , the application also provides a flow demand control device for electric engineering machinery, which comprises:

[0139] at least one processor; and

[0140] a memory in communication connection with the at least one processor; wherein

[0141] 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 perform the flow demand control method for electric engineering machinery according to any one of the above embodiments.

[0142] The application also provides a non-volatile computer storage medium, which stores computer executable instructions, and the computer executable instructions are configured to implement the flow demand control method for the electric engineering machinery.

[0143] The embodiments of the application are described in a progressive manner, and the same or similar parts of the embodiments can be referred to each other. Each embodiment mainly describes the difference from other embodiments. In particular, the device and medium embodiments are basically similar to the method embodiments, and thus the description is relatively simple, and the relevant parts can be referred to the description of the method embodiments.

[0144] The device and medium provided by the embodiments of the application are one-to-one corresponding to the method, and thus the device and medium also have the similar beneficial technical effects as the 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 described here.

[0145] The above only describes the embodiments of the application and is not intended to limit the application. The application can be variously changed and modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application shall be included in the scope of the claims of the application.

Claims

1. A method of flow demand control for an electrically powered working machine, characterized by, The method comprises the following steps: determining the pilot handle opening value according to the pilot handle opening voltage value; obtaining the hydraulic oil demand flow value according to the pilot handle opening value and the preset hydraulic oil demand response characteristic value; obtaining the main pump pressure value and dynamically correcting the hydraulic oil demand flow value according to the main pump pressure value to obtain the corrected flow value; adjusting the current of the first proportional valve according to the corrected flow value to control the opening value of the first proportional valve; obtaining the hydraulic oil demand flow value according to the pilot handle opening value and the preset hydraulic oil demand response characteristic value, specifically comprising: determining the preset calibration opening value and the hydraulic oil demand response characteristic value; wherein the hydraulic oil demand response characteristic value is positively correlated with the hydraulic oil control response condition; when the pilot handle opening value is lower than the calibration opening value, taking the minimum value of the hydraulic oil demand flow value as the K value to generate a first linear relationship according to the hydraulic oil demand response characteristic value; determining the hydraulic oil demand flow value corresponding to the specified flow value of the calibration opening value according to the first linear relationship; when the pilot handle opening value is higher than the calibration opening value, generating a second linear relationship according to the specified flow value and the maximum value of the hydraulic oil demand flow value.

2. The method of claim 1, wherein, determining the pilot handle opening value according to the pilot handle opening voltage value, specifically comprising: determining the voltage output range of the pilot handle opening voltage value and setting multiple voltage output intervals according to the voltage output range; if the pilot handle opening voltage value hits the voltage output interval at both ends, determining the pilot handle opening value as the fixed value corresponding to the voltage output interval; if the pilot handle opening voltage value hits the voltage output interval in the middle, determining the corresponding pilot handle opening value based on the percentage position of the pilot handle opening voltage value in the voltage output interval.

3. The method of claim 1, wherein, dynamically correcting the hydraulic oil demand flow value according to the main pump pressure value to obtain the corrected flow value, specifically comprising: determining the main pump turning pressure value according to the maximum output flow of the main pump and the maximum absorption power of the main pump; determining the preset overflow protection pressure value and the calibration pressure value lower than the overflow protection pressure value; when the main pump pressure value is less than the main pump turning pressure value, directly taking the hydraulic oil demand flow value as the corrected flow value; when the main pump pressure value is greater than the main pump turning pressure value and lower than the calibration pressure value, calculating the corrected flow value according to the main pump pressure value and the maximum absorption power of the main pump; when the main pump pressure value is greater than the calibration pressure value, adjusting the main pump pressure value to make it lower than the overflow protection pressure value.

4. The method of claim 3, wherein, The method further comprises: obtaining the corresponding main pump pressure value by pre-setting multiple pressure sensors; determining the dynamic weight factor of the pressure sensor based on the setting position of the pressure sensor; When the main pump pressure value corresponding to at least one pressure sensor is greater than the main pump turning pressure value or the calibration pressure value, the main pump pressure values corresponding to all pressure sensors are weighted and summed by a first weight factor and a second weight factor respectively to obtain a comprehensive main pump pressure value, and whether the main pump pressure value reaches the main pump turning pressure value or the calibration pressure value is determined by the comprehensive main pump pressure value. The second weight factor has a lower discrete degree of dynamic weight factors between different pressure sensors than the first weight factor.

5. The method of claim 1, wherein, According to the modified flow value, the current of the first proportional valve is adjusted, and the opening value of the first proportional valve is controlled, specifically including: The positive terminal of the coil of the first proportional valve is connected to the output terminal of the high-side drive chip, and the high-side drive of the electromagnetic valve is realized through the high-side drive chip; After the negative terminal of the coil of the first proportional valve is connected to the current sampling resistor, the low-side drive of the electromagnetic valve is realized through the low-side drive MOS tube, and the control of the MOS tube is realized through the low-end drive chip.

6. The method of claim 1, wherein, The method further includes: The hydraulic pump module to which the first proportional valve belongs is determined, and the vehicle system to which the hydraulic pump module belongs is determined; the vehicle system includes: a boom energy recovery module, a swing energy recovery module, a hydraulic pump module, a battery module, a power grid module, and a direct current bus; The boom energy recovery module is connected to the direct current bus through a boost DC-DC converter, and the electrical energy recovered by the boom energy recovery module is transmitted to the direct current bus; The swing energy recovery module is connected to the direct current bus, and the electrical energy recovered by the swing energy recovery module is transmitted to the direct current bus; The hydraulic pump module is connected to the direct current bus, and the electrical energy transmitted by the direct current bus is received to drive the hydraulic pump to work; The battery module is connected to the direct current bus through a bidirectional DC-DC converter, receives the electrical energy transmitted by the direct current bus for charging, and / or transmits electrical energy to the direct current bus; The power grid module is connected to the direct current bus through a rectifier module, and transmits electrical energy to the direct current bus.

7. The method of claim 6, wherein, The boom energy recovery module includes a second proportional valve, a boom hydraulic motor, a generator, a rectifier bridge, and a boost DC-DC converter connected in sequence. The energy recovery process of the swing energy recovery module includes: The boom lowering handle opening is obtained, and the control proportional valve opening is determined according to the boom lowering handle opening; the boom lowering handle opening and the control proportional valve opening are negatively correlated; The flow of the boom lowering high-pressure hydraulic oil flowing into the boom hydraulic motor is adjusted through the second proportional valve; The generator is driven by the high-pressure hydraulic oil through the boom hydraulic motor; 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 direct current energy is boosted through the boost DC-DC converter, and the boosted direct current energy is transmitted to the direct current bus.

8. The method of claim 6, wherein, The swing energy recovery module includes a swing hydraulic motor and a low-speed large-torque motor. The energy recovery process of the swing energy recovery module includes: The swing handle opening is obtained. When the swing handle opening is greater than a preset swing opening value, a swing speed is obtained; When the swing speed is lower than a preset speed, the swing hydraulic motor and the low-speed large-torque motor are controlled to work; When the swing speed is higher than the preset speed, the swing hydraulic motor is controlled to be closed, and the low-speed large-torque motor is controlled to work alone; When the swing handle opening is reduced to be lower than the preset swing opening value, the swing hydraulic motor is controlled to be closed, and the low-speed large-torque motor is controlled to reduce speed, so as to convert swing energy into electric energy and deliver the electric energy to a direct-current bus.

9. A flow demand control device for an electrically powered engineering machine, characterized by Comprise: At least one processor; And The memory is in communication connection with 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 flow demand control method for the electric engineering machinery according to any one of claims 1-8.

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