Flow demand control method and equipment for electric engineering machinery

Abstract

The invention discloses a flow demand control method and device for electric engineering machinery, and the method comprises the steps: determining a pilot handle opening value according to a pilot handle opening voltage value; according to the pilot handle opening value and a preset hydraulic oil demand response characteristic value, a hydraulic oil demand flow value is obtained; a main pump pressure value is obtained, the hydraulic oil demand flow value is dynamically corrected according to the main pump pressure value, and a corrected flow value is obtained; and the current of the first proportional valve is adjusted according to the corrected flow value, and the opening value of the first proportional valve is controlled. The flow demand is corrected in real time through the main pump pressure, high-pressure working condition overpower output is avoided, the overflow frequency is reduced, and dynamic pressure correction is achieved.

Description

Technical Field

[0001] This application relates to the field of flow control, and specifically to a flow demand control method and device for electric construction machinery. Background Art

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

[0003] However, traditional solutions have the following disadvantages:

[0004] 1. Open-loop control, relying on empirical calibration: Traditional solutions control the flow through a fixed curve (such as the handle opening - flow linear mapping), which easily leads to flow overlimit under high-pressure conditions, causing overflow or power overload.

[0005] 2. Static response characteristics: Using a flow response curve with a fixed slope, it is difficult to adapt to different operating scenarios (for example, fine operation requires low sensitivity, and heavy load requires high response), and the handling 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 after converting from fuel to electricity, the short-term overload capacity of the motor is likely to cause the hydraulic pump to be damaged due to over-power. Summary of the Invention

[0007] To solve the above problems, this application proposes a flow demand control method for electric construction machinery, including:

[0008] Determine the pilot handle opening value according to the pilot handle opening voltage value;

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

[0010] 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;

[0011] Adjust 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, determining the pilot handle opening value according to the pilot handle opening voltage value specifically includes:

[0013] Determine the voltage output range of the pilot handle opening voltage value, and set multiple voltage output intervals according to the voltage output range;

[0014] If the pilot handle opening voltage value falls within the voltage output range at both ends, determine the pilot handle opening value as the fixed value corresponding to this voltage output range;

[0015] If the pilot handle opening voltage value falls within the voltage output range in the middle, determine the corresponding pilot handle opening value based on the percentage position of the pilot handle opening voltage value within this voltage output range.

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

[0017] Determine a preset calibrated opening value and a hydraulic oil demand response characteristic value; wherein, the hydraulic oil demand response characteristic value is positively correlated with the hydraulic oil control response situation;

[0018] When the pilot handle opening value is lower than the calibrated opening value, use the lowest value of the hydraulic oil demand flow value, take the hydraulic oil demand response characteristic value as the K value, and generate a first linear relationship;

[0019] According to the first linear relationship, determine the specified flow value corresponding to the calibrated opening value for the hydraulic oil demand flow value;

[0020] When the pilot handle opening value is higher than the calibrated opening value, generate a second linear relationship based on the specified flow value and the highest value of the hydraulic oil demand flow value.

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

[0022] Determine 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; and determine a preset overflow protection pressure value and a calibrated pressure value lower than the overflow protection pressure value;

[0023] When the main pump pressure value is less than the main pump turning pressure value, directly use the hydraulic oil demand flow value 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 calibrated pressure value, calculate the corrected flow value according to the main pump pressure value and the maximum absorption power of the main pump;

[0025] When the main pump pressure value is greater than the calibrated pressure value, adjust the main pump pressure value so that the main pump pressure value is lower than the overflow protection pressure value.

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

[0027] By presetting multiple pressure sensors, the corresponding main pump pressure values are obtained respectively;

[0028] Based on the set positions of the pressure sensors, the dynamic weight factors of the pressure sensors are determined;

[0029] When there is at least one main pump pressure value corresponding to a pressure sensor greater than the main pump transition pressure value or the calibrated pressure value, the main pump pressure values corresponding to all pressure sensors are weighted and summed respectively through the first weight factor and the second weight factor to obtain a comprehensive main pump pressure value, and whether the main pump pressure value reaches the main pump transition pressure value or the calibrated pressure value is determined through the comprehensive main pump pressure value;

[0030] Wherein, compared with the first weight factor, the second weight factor has a lower degree of dispersion of the dynamic weight factors among different pressure sensors.

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

[0032] It is determined that the positive end of the first proportional valve coil is connected to the output end of the high-side drive chip, and the high-side drive of the solenoid valve is performed through the high-side drive chip;

[0033] It is determined that after the negative end of the first proportional valve coil is connected to the current sampling resistor, the low-side drive of the solenoid valve is performed through the MOS tube of the low-side drive; wherein, the control of the MOS tube is realized through the low-side drive chip.

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

[0035] Determine the hydraulic pump module to which the first proportional valve belongs, and the vehicle system to which the hydraulic pump module belongs; wherein, the vehicle system includes: a boom energy recovery module, a slewing energy recovery module, a hydraulic pump module, a battery module, a power grid module, and a DC bus;

[0036] 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;

[0037] The slewing energy recovery module is connected to the DC bus, and conveys the electric energy recovered to the DC bus;

[0038] The hydraulic pump module is connected to the DC bus, and drives the hydraulic pump to work by receiving the electric energy conveyed by the DC bus;

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

[0040] The power grid module is connected to the DC bus through a rectification module and transmits electrical energy to the DC bus.

[0041] In one example, the boom energy recovery module includes, connected in sequence: a second proportional valve, a boom hydraulic motor, a generator, a rectifier bridge, and a boost DC-DC converter;

[0042] The energy recovery process of the slewing energy recovery module includes:

[0043] 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;

[0044] Adjust the flow rate of the high-pressure hydraulic oil for boom lowering flowing into the boom hydraulic motor through the second proportional valve;

[0045] Drive the generator through the high-pressure hydraulic oil by the boom hydraulic motor;

[0046] Convert mechanical energy into AC electrical energy through the generator;

[0047] Convert AC electrical energy into DC electrical energy through the rectifier bridge;

[0048] Boost the DC electrical energy through the boost DC-DC converter and transmit the boosted DC electrical energy to the DC bus.

[0049] In one example, the slewing energy recovery module includes a slewing hydraulic motor and a low-speed high-torque motor;

[0050] The energy recovery process of the slewing energy recovery module includes:

[0051] Obtain the opening degree of the slewing handle;

[0052] When the opening degree of the slewing handle is greater than a preset slewing opening value, obtain the slewing speed;

[0053] When the slewing speed is lower than a preset speed, control the slewing hydraulic motor and the low-speed high-torque motor to operate;

[0054] When the slewing speed is higher than a preset speed, control the slewing hydraulic motor to close and separately control the low-speed high-torque motor to operate;

[0055] When the opening degree of the slewing handle decreases 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.

[0056] On the other hand, the present application also proposes a flow demand control device for electric construction machinery, including:

[0057] At least one processor; and,

[0058] A memory communicatively connected to 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: the flow demand control method for electric construction machinery described in any of the above examples.

[0060] 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 flow demand control method for electric construction machinery described in any of the above examples.

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

[0062] 1. Real-time correction of the flow demand by the main pump pressure, avoiding over-power output under high-pressure conditions, reducing the overflow frequency, and realizing dynamic pressure correction.

[0063] 2. Presetting the hydraulic oil demand response characteristic value, supporting sensitivity adjustment in different scenarios, improving the control adaptability, and realizing adjustable response characteristics.

[0064] 3. Coupling the handle opening degree and the pressure, giving priority to responding to the operation intention, while ensuring system safety, realizing human-machine collaborative optimization, and improving the operation efficiency and reliability. Description of the Drawings

[0065] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation to the present application. In the drawings:

[0066] Figure 1 It is a flow schematic diagram of the flow demand control method for electric construction machinery in the embodiment of the present application;

[0067] Figure 2 It is a hydraulic oil response characteristic diagram in a certain situation in the embodiment of the present application;

[0068] Figure 3In one case of the embodiments of the present application, it is a curve graph of the maximum flow safety output range;

[0069] Figure 4 In one case of the embodiments of the present application, it is a drive circuit diagram of a proportional solenoid valve;

[0070] Figure 5 In one case of the embodiments of the present application, it is a module schematic diagram of a vehicle system;

[0071] Figure 6 In one case of the embodiments of the present application, it is a structural schematic diagram of a rectification module;

[0072] Figure 7 In the embodiments of the present application, it is a schematic diagram of a flow demand control device for electric construction machinery. Detailed implementation manners

[0073] 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 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts belong to the scope of protection of the present application.

[0074] The following will, in conjunction with the drawings, elaborate on the technical solutions provided by the embodiments of the present application.

[0075] As Figure 1 shown, the embodiments of the present application provide a flow demand control method for electric construction machinery, including:

[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, an electric excavator is taken as an example of electric construction machinery for explanation. Determine the voltage output range of the pilot handle opening voltage value, and set multiple voltage output intervals according to the voltage output range. Here, the voltage output range is set as V 1 ~V 2 , and at this time, three voltage output intervals can be set.

[0078] If the pilot handle opening voltage value hits the voltage output intervals at both ends, determine that the pilot handle opening value is the fixed value corresponding to this voltage output interval. For the voltage output intervals at both ends, when it is the voltage output interval at the lower limit end, it can be considered that the driver's purpose is not to operate the pilot handle, which is usually a mis-touch, so the fixed value can be 0, and when it is the voltage output interval at the upper limit end, it can be considered that the driver wants to fully operate the pilot handle, so the fixed value can be 100%.

[0079] If the pilot handle opening voltage value falls within the middle voltage output range, determine the corresponding pilot handle opening value based on the percentage position of the pilot handle opening voltage value within this voltage output range, that is, according to the driver's operation degree, reflect the corresponding pilot handle opening value.

[0080] For example, set the threshold voltages of the pilot handle to V L = V 1 + 0.3 and V H = V 2 - 0.3. At this time, set three voltage output ranges, which are 0 to V L , V L to V H , V H to 100%.

[0081] Define the current voltage value of the pilot handle as U, then the percentage of the pilot handle opening is P ed As shown in Formula 1:

[0082]

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

[0084] Specifically, determine the preset calibrated opening value and the hydraulic oil demand response characteristic value; among them, the hydraulic oil demand response characteristic value is positively correlated with the hydraulic oil control response situation, that is, the better the hydraulic oil control response situation, the higher the hydraulic oil demand response characteristic value. And the calibrated opening value can be a fixed value, for example, it can be set to 60%.

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

[0086] According to the first linear relationship, determine the specified flow value corresponding to the calibrated opening value of the hydraulic oil demand flow value. When the pilot handle opening value reaches the calibrated opening value, it has entered the high opening area. If it continues to advance at 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 is necessary to enter the progressive saturation control stage to ensure that when the pilot handle opening value P ed is 100%, regardless of the value of the K value, the hydraulic oil demand flow value Q 1 can reach 100%.

[0087] Therefore, when the pilot handle opening value is higher than the calibrated opening value, a second linear relationship is generated based on the specified flow value and the maximum value of the hydraulic oil required flow value. The K value in this stage is different from the K value in the previous stage to ensure that when the pilot handle opening value P ed is 100%, the hydraulic oil required flow value Q 1 can reach 100%.

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

[0089] At this time, the hydraulic oil required flow percentage Q 1 calculated according to the handle opening value and the hydraulic oil demand response characteristic value is as shown in Formula 2:

[0090]

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

[0092] After the engineering machinery is converted from fuel to electricity to become an electric engineering machinery, generally, the absorption power of the hydraulic pump is greater than the rated output power of the engine, making it difficult to fully exert the capacity of the hydraulic pump. Moreover, the rated power of the motor matched for the engineering machinery fuel-to-electricity conversion is the same as that of the engine, but the motor can output 2 to 3 times the rated power overload. In the case of the motor outputting overload, 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 engineering machinery is converted from fuel to electricity to form an 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 to ensure safety.

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

[0095] the preset overflow protection pressure value P out is determined, as well as the calibrated pressure value P 1。

[0096] At this time, as Figure 3 shown, the correction strategy includes:

[0097] When the main pump pressure value is less than the main pump transition pressure value, directly use the hydraulic oil demand flow rate value Q 1 as the corrected flow rate value, that is, do not correct Q 1 for correction.

[0098] When the main pump pressure value is greater than the main pump transition pressure value and lower than the calibration pressure value, enter the constant power control mode. According to the main pump pressure value and the main pump maximum absorption power, calculate the corrected flow rate value to ensure that the power does not exceed the limit. Among them, the corrected flow rate value can be obtained by dividing the main pump maximum absorption power by the main pump pressure value.

[0099] When the main pump pressure value is greater than the calibration pressure value, enter the overflow protection mode. Generally speaking, the construction machinery hydraulic system is provided with an overflow valve. When the main pump pressure value exceeds the set overflow pressure value, the overflow valve opens, and a large amount of energy will be wasted during the overflow process.

[0100] Therefore, in order to exert the hydraulic system capacity and avoid overflow at the same time, after calibration testing, select a pressure value P out that is slightly smaller than the overflow valve opening pressure value out as the overflow protection pressure value, and design a pressure value P 1 that is even smaller than the overflow protection pressure value P 1 <P out <overflow valve opening pressure value.

[0101] When the main pump pressure value is greater than the calibration pressure value, jump out of the constant power control mode and enter the overflow protection mode. With the overflow protection pressure value P out as the control target, adjust the main pump pressure value so that the main pump pressure value is lower than the overflow protection pressure value, realizing that the hydraulic system pressure does not exceed the overflow pressure, and at the same time ensuring the system power output.

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

[0103] At this time, based on the setting 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 different actual conditions. However, the weight factor still needs to be set with a corresponding size relationship. For example, the size of the weight factor is from high to low: the outlet end of the main pump, the inlet end of the valve group, and the actuator end. The closer to the main pump, the higher the weight factor.

[0104] 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 calibrated pressure value, it is considered that the flow value may need to be corrected at present. However, in order to further determine whether it is caused by the detection abnormality of a certain pressure sensor, at this time, the main pump pressure values ​​corresponding to all pressure sensors are weighted and summed by the first weight factor (corresponding to the main pump pressure value being greater than the main pump turning pressure value and less than the calibrated pressure value) and the second weight factor (corresponding to the main pump pressure value being greater than the calibrated pressure value) 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 calibrated pressure value. By judging the comprehensive pressure value, the misjudgment caused by the abnormality of a certain pressure sensor can be resolved.

[0105] Among them, the situation where the main pump pressure value is greater than the calibrated pressure value is higher than the situation where the main pump pressure value is greater than the main pump turning pressure value. The situation is relatively more serious. At this time, all sensors will be affected by the same physical phenomenon at the same time, which is easy to destroy the dynamic balance of the system and cause the pressure distribution to be more uniform. Therefore, no matter where the pressure sensor is set, its readings tend to converge.

[0106] Based on this, the second weight factor has a lower degree of discreteness in the dynamic weight factors between different pressure sensors than the first weight factor. A lower degree of discreteness means that the weights between the pressure sensors are closer, which is more consistent with the situation that the pressure sensor readings converge when the situation is serious. For example, in the first weight factor, the weight factors of the main pump outlet, the valve group inlet, and the actuator 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: According to the corrected flow value, the current of the first proportional valve is adjusted to control the opening value of the first proportional valve.

[0108] Based on this, the calculation of the hydraulic oil demand flow value (that is, the corrected flow value) coupled by the pilot handle opening value and the main pump pressure value has been realized, and the actual hydraulic oil volume output is achieved 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 on the first proportional valve.

[0109] Based on this, Figure 4As shown, a proportional solenoid valve drive circuit with controllable high and low sides is set up, and a corresponding current control strategy is formulated.

[0110] Specifically, it is determined that the positive terminal of the coil of the first proportional valve is connected to the output terminal of a high-side drive chip ( Figure 4 which is BTS5215 in this case), and the high side of the solenoid valve is driven by the high-side drive chip BTS5215.

[0111] After determining that the negative terminal of the coil of the first proportional valve is connected to a current sampling resistor, the low side of the solenoid valve is driven by a MOS transistor for low-side drive ( Figure 4 which is FQD20N03 in this case); among them, the control of the MOS transistor is achieved through a low-side drive chip ( Figure 4 which is IR4427S in this case).

[0112] In one embodiment, the first proportional valve belongs to a hydraulic pump module, and the hydraulic pump module is a module in a vehicle system. When the main pump (such as the hydraulic pump shown Figure 5 in this case) is controlled by the first proportional valve to output a corresponding flow rate, it can control other modules of the vehicle system accordingly, so as to carry out corresponding mechanical work. For example, it can control the boom movement, control the slewing, etc.

[0113] However, in the actual working process, since the working scenarios of construction machinery are usually industrial scenarios, involving frequent boom lowering, slewing braking and other working conditions, the electric construction machinery consumes a huge amount of energy during operation, and a large amount of energy is wasted in the forms of heat energy, mechanical energy, etc.

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

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

[0116] Among them, the boom energy recovery module is mainly used to recover energy using potential energy when the boom is lowered and finally convert it into electrical energy. It is connected to the DC bus through a boost DC-DC converter (boost DCDC), and conveys the electrical energy recovered to the DC bus.

[0117] The slewing energy recovery module is mainly used to recover energy using kinetic energy when the electric construction machinery is slewing and finally convert it into electrical energy. It is connected to the DC bus and conveys the electrical energy recovered to the DC bus.

[0118] The hydraulic pump module is connected to the DC bus. By receiving the electric energy transmitted by the DC bus, it drives the hydraulic pump to work, and the hydraulic pump can drive the hydraulic motors in the boom and slewing device to work.

[0119] 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 transmitted by the DC bus for charging and / or transmit electric energy to the DC bus, that is, perform discharging.

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

[0121] Further, as Figure 5 shown, for the boom energy recovery module, it includes the following components connected in sequence: a second proportional valve (for regulating the flow rate of the high-pressure hydraulic oil flowing into the boom hydraulic motor during boom lowering), a boom hydraulic motor (for driving a generator using high-pressure hydraulic oil), a generator (for converting 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).

[0122] During energy recovery, first obtain the boom lowering handle opening, and determine the control of the second proportional valve opening according to the boom lowering handle opening; among them, the boom lowering handle opening is negatively correlated with the control of the second proportional valve opening.

[0123] In actual work, through the second proportional valve, the flow rate of the high-pressure hydraulic oil flowing into the boom hydraulic motor during boom lowering is regulated; through the boom hydraulic motor, the generator is driven by high-pressure hydraulic oil; through the generator, mechanical energy is converted into alternating current; through the rectifier bridge, the alternating current is converted into direct current; through the boost DC-DC converter, the direct current is boosted and the boosted direct current is transmitted to the DC bus.

[0124] For example, define the boom lowering handle opening range as 0-100%. When the boom lowering handle opening is less than the first preset lowering opening value, it is considered that the required boom lowering speed is relatively small at this time, and the control of the second proportional valve opening 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 electric energy and transmitting it to the DC bus.

[0125] When the opening of the boom lowering handle is greater than the first preset lowering opening value and less than the second preset lowering opening value (which is higher than the first preset lowering opening value), in this working condition, while considering the required speed of the boom lowering, energy recovery is also taken into account, and the opening of the second proportional valve is reduced from a relatively high value to a preset value Q 2 value, so that part of the hydraulic oil for the boom lowering returns to the fuel tank through the original vehicle oil circuit to ensure the boom lowering speed, while the remaining part of the hydraulic oil for the boom lowering flows into the hydraulic motor to drive the generator to generate electricity.

[0126] When the opening of the boom lowering handle 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 maintained at the Q 2 value unchanged. This value can ensure the normal boom lowering speed, meet the driver's operation, and at the same time, a part of the energy recovery during the boom lowering can be achieved.

[0127] As Figure 5 shown, for the slewing energy recovery module, it includes a slewing hydraulic motor and a low-speed high-torque motor. Generally, there are multiple slewing hydraulic motors in electric construction machinery. Taking the example of including two slewing hydraulic motors, one of the slewing hydraulic motors can be replaced by a low-speed high-torque motor. In addition, before replacing the low-speed high-torque motor, the functional relationship between the slewing handle opening of the electric construction machinery with two slewing hydraulic motors and the slewing speed of the excavator can be calibrated to facilitate the subsequent acquisition of the slewing speed.

[0128] Define the slewing handle opening range as 0 - 100%, and obtain the slewing handle opening.

[0129] When the slewing handle opening is less than the preset slewing opening value, it is considered at this time that the electric construction machinery does not perform a slewing action, and the system controls the slewing hydraulic motor to work to maintain the non-rotation action of the excavator.

[0130] When the slewing handle opening is greater than the preset slewing opening value, obtain the slewing speed. It can be obtained through the functional relationship calibrated above, or 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 slewing start stage of the excavator. In this stage, the required starting torque is relatively large. Control the slewing hydraulic motor and the low-speed high-torque motor to work, and set the target speed to the preset speed to make the slewing speed quickly reach the preset speed.

[0132] When the slewing speed is higher than the preset speed, it is considered that the slewing start stage is completed, and it enters the excavator rotation stage. In this stage, the required rotation torque is less than the slewing starting torque. Control the slewing hydraulic motor to close, and separately control the low-speed high-torque motor to work.

[0133] When the opening of the slewing handle starts to decrease from large to small until it drops below the preset opening value (even reset to 0), this stage is defined as the slewing deceleration and stop stage. The slewing hydraulic motor is still controlled to close, and the low-speed high-torque motor is controlled to decelerate, converting the slewing energy into electrical energy and transmitting it to the DC bus. Among them, this energy recovery aims at maximum energy recovery, without current limit for recovery. The maximum current and voltage of the motor controller are used as the target for braking energy feedback to achieve maximum energy recovery.

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

[0135] The short-circuit protector protects the vehicle system current and cuts off the power supply to the system when the system current exceeds the maximum system current; the AC contactor cooperates with the start and stop buttons to control the power supply to the vehicle system; the autotransformer boosts the AC voltage to make the voltage reach the AC voltage required by the electric construction machinery; the rectification bridge converts the high-voltage AC into the high-voltage DC required by the electric construction machinery; the bus capacitor filters and stores the energy of the high-voltage DC.

[0136] The pre-charge unit includes a pre-charge resistor, a DC contactor, and a voltmeter. The pre-charge resistor is connected in series between the positive pole of the rectification bridge and the positive pole of the bus capacitor. When the high voltage charges the bus capacitor through the pre-charge resistor, the bus voltage is monitored synchronously through the voltmeter. When the bus voltage exceeds the preset pre-charge end voltage, the DC contactor is controlled to close to complete the pre-charge process.

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

[0138] As Figure 7 shown, the embodiment of the present application also proposes a flow demand control device for electric construction machinery, including:

[0139] At least one processor; and,

[0140] A memory communicatively connected to 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: the flow demand control method for electric construction machinery described in any of the above embodiments.

[0142] An embodiment of the present application also provides a non-volatile computer storage medium storing computer-executable instructions, where the computer-executable instructions are configured as: the flow demand control method for electric construction machinery according to any of the above embodiments.

[0143] The various embodiments in the present application are described in a progressive manner. For the same or similar parts among the various embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the embodiments of the device and the medium, since they are basically similar to the method embodiments, the description is relatively simple, and for the relevant parts, reference can be made to the partial description of the method embodiments.

[0144] The device and the medium provided in the embodiments of the present application correspond one-to-one with the method. Therefore, the device and the 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 the medium will not be elaborated here.

[0145] 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 modifications and changes 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. A flow demand control method for electric engineering machinery, characterized in that: include: According to the pilot handle opening voltage value, determine the pilot handle opening value; According to the pilot handle opening value and the preset hydraulic oil demand response characteristic value, a hydraulic oil demand flow value is obtained; 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; According to the corrected flow value, the current of the first proportional valve is adjusted to control the opening value of the first proportional valve.

2. The method according to claim 1, characterized in that According to the pilot handle opening voltage value, determine the pilot handle opening value, including: Determine a voltage output range of the pilot handle opening voltage value, and set a plurality of voltage output intervals according to the voltage output range; If the pilot handle opening voltage value hits the voltage output interval at both ends, then the pilot handle opening value is determined to be a fixed value corresponding to the voltage output interval; If the pilot handle opening voltage value hits the middle voltage output interval, the corresponding pilot handle opening value is determined based on the percentage position of the pilot handle opening voltage value in the voltage output interval.

3. The method according to claim 1, characterized in that According to the pilot handle opening value and the preset hydraulic oil demand response characteristic value, the hydraulic oil demand flow value is obtained, which specifically includes: Determine a preset calibrated opening value and a 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 calibrated opening value, the hydraulic oil demand response characteristic value is used as the K value according to the lowest value of the hydraulic oil demand flow value to generate a first linear relationship; Determine, according to the first linear relationship, a specified flow value of the hydraulic oil demand flow value corresponding to the calibrated opening value; When the pilot handle opening value is higher than the calibrated 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.

4. The method according to claim 1, characterized in that The hydraulic oil demand flow value is dynamically corrected according to the main pump pressure value to obtain a corrected flow value, specifically including: Determine the turning pressure value of the main pump according to the maximum output flow of the main pump and the maximum absorbed power of the main pump; and determine the preset overflow protection pressure value and the calibrated pressure value lower than the overflow protection pressure value; When the main pump pressure value is less than the main pump turning pressure value, the hydraulic oil required flow value is directly used as the corrected flow value; When the main pump pressure value is greater than the main pump turning pressure value and lower than the calibrated pressure value, a corrected flow value is calculated according to the main pump pressure value and the maximum absorbed power of the main pump; When the main pump pressure value is greater than the calibrated pressure value, the main pump pressure value is adjusted to make the main pump pressure value lower than the overflow protection pressure value.

5. The method according to claim 4, characterized in that The method further comprises: By pre-setting multiple pressure sensors, corresponding main pump pressure values ​​are obtained respectively; Determining a dynamic weight factor of the pressure sensor based on a setting position of the pressure sensor; When there is at least one pressure sensor corresponding to a main pump pressure value greater than the main pump turning pressure value or the calibrated pressure value, weighted summing the main pump pressure values ​​corresponding to all pressure sensors is performed using a first weight factor and a second weight factor, respectively, to obtain a comprehensive main pump pressure value, and determining whether the main pump pressure value reaches the main pump turning pressure value or the calibrated pressure value using the comprehensive main pump pressure value; Among them, compared with the first weight factor, the discrete degree of the dynamic weight factor between different pressure sensors in the second weight factor is lower.

6. The method according to claim 1, characterized in that According to the corrected flow value, adjusting the current of the first proportional valve to control the opening value of the first proportional valve specifically includes: Determine that the positive end of the first proportional valve coil is connected to the output end of the high-side driver chip, and drive the high side of the electromagnetic valve through the high-side driver chip; After determining the current sampling resistor connected to the negative terminal of the coil of the first proportional valve, the low side of the electromagnetic valve is driven by a low side driving MOS tube; wherein the control of the MOS tube is realized by a low side driving chip.

7. The method according to claim 1, characterized in that The method further comprises: Determine the hydraulic pump module to which the first proportional valve belongs, and the vehicle system to which the hydraulic pump module belongs; wherein 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 DC bus; The arm energy recovery module is connected to the DC bus through a boost DC-DC converter to transmit the electric energy obtained by energy recovery to the DC bus; The rotary energy recovery module is connected to the DC bus to transmit the electric energy obtained by energy recovery to the DC bus; The hydraulic pump module is connected to the DC bus and drives the hydraulic pump to work by receiving the electric energy transmitted by the DC bus; The battery module is connected to the DC bus through a bidirectional DC-DC converter, receives electric energy transmitted by the DC bus for charging, and / or transmits electric energy to the DC bus; The grid module is connected to the DC bus through a rectifier module to transmit electric energy to the DC bus.

8. The method according to claim 7, characterized in that 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 rotary energy recovery module includes: Acquire the opening of the boom lowering handle, and determine the opening of the control proportional valve according to the opening of the boom lowering handle; wherein the opening of the boom lowering handle is negatively correlated with the opening of the control proportional valve; The flow rate of the boom lowering high-pressure hydraulic oil flowing into the boom hydraulic motor is regulated by the second proportional valve; The boom hydraulic motor drives the generator through high-pressure hydraulic oil; The mechanical energy is converted into AC electrical energy by the generator; The AC power is converted into DC power by the rectifier bridge; The DC power is boosted by the boost DC-DC converter, and the boosted DC power is transmitted to the DC bus.

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

10. A flow demand control device for electric engineering machinery, characterized in that: include: at least one processor; as well as, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions 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: implement the flow demand control method for electric engineering machinery as described in any one of claims 1 to 9.

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