Dual-power excavator hydraulic system and control method thereof

Abstract

The invention discloses a dual-power excavator hydraulic system and a control method thereof, and belongs to the technical field of engineering machinery. The hydraulic system overcomes the defects that in the prior art, two sets of main pumps are arranged on a traditional excavator hydraulic system machine, the production and manufacturing cost is high, and the occupied space is large. The main body structure comprises a working system, a motor, a light energy power supply system, a heat dissipation system, a variable frequency motor and an electric energy transmission system, the light energy power supply system is connected with the working system through the motor, the working system is further connected with a hydraulic execution element and an oil return system, and the electric energy transmission system is connected with the heat dissipation system through the variable frequency motor. The invention is mainly applied to engineering machinery such as excavators.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering machinery, and in particular, relates to a dual-power excavator hydraulic system and a control method thereof. Background Art

[0002] In the field of engineering machinery, especially excavators, the hydraulic pump is usually driven by the engine to provide power for the hydraulic system of the whole machine, so as to achieve actions such as excavation and unloading. However, the engine as a power source will produce a certain degree of fuel exhaust emissions and noise, polluting the environment and not conducive to energy conservation and emission reduction. Compared with the engine, when the motor is used as a power source, the noise is small and pollution-free, and the operating cost is greatly reduced; but in order to ensure the stable operation of the motor, an external power grid is required, and it can only work in places with an external power grid, and it is inconvenient to transfer. Combining the advantages of the two, the dual-power excavator came into being.

[0003] The existing main pump oil supply system of oil-electric dual-power excavator is as follows Figure 7 As shown, the engine drives one group of main pumps, and the motor drives one group of main pumps. These two groups of main pumps work independently, but drive the same actuator through the same main control valve. The hydraulic circuit is that the motor drives the main pump, the engine drives the main pump, the main pump oil outlet is connected to the one-way valve, the main pump is connected to the one-way valve, and the pipeline is combined to connect to the control valve to enter the actuator. The main pump is connected in parallel with the main pump, and the output oil passes through the one-way valve and the one-way valve separately through the control valve group to enter the load hydraulic power system to drive the excavator to work. However, the above scheme has the following shortcomings:

[0004] 1. Use the motor and the engine to drive a set of main pumps to achieve independent work, that is, there are two sets of main pumps on the machine, which increases the production cost and occupies a large space. At the same time, additional one-way valves are required at the outlets of the two sets of main pumps, and the pipeline connection is cumbersome and complicated, increasing the risk of leakage;

[0005] 2. The electric energy of the motor is obtained from the power grid. Since the electricity in the power grid is generated by coal and fossil fuels, it pollutes the environment;

[0006] 3. The hydraulic system often recovers energy through hydraulic cylinders or rotary motors. Because during the operation of the excavator, the movements of the hydraulic cylinders and rotary motors are periodic and have a large range of motion, the recovered energy has large fluctuations and impacts and is difficult to control. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a dual-power excavator hydraulic system and a control method thereof.

[0008] In order to achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0009] A dual-power excavator hydraulic system includes a working system, an electric motor, a solar power supply system, a heat dissipation system, a variable frequency motor and an electric power transmission system. The solar power supply system is connected to the working system through the electric motor, the working system is also connected to the hydraulic actuator and the oil return system respectively, and the electric power transmission system is connected to the heat dissipation system through the variable frequency motor.

[0010] Preferably, the solar power supply system includes a concentrator for collecting light sources, a solar cell group for generating direct current, a convergence device, a DC voltage stabilizing module, an energy storage device and an inverter module for outputting three-phase alternating current. The concentrator is connected to the convergence device through the solar cell group, and the convergence device is also electrically connected to the DC voltage stabilizing module through an LCL filter. One side of the DC voltage stabilizing module is connected to the input port of the energy storage device, and the energy storage device is connected in parallel with the DC bus through a photoelectric contactor; the input end of the inverter module is connected in parallel with the DC side of the DC bus, and the output end of the inverter module is connected to the motor.

[0011] Preferably, the electric energy transmission system includes an electric energy integration module, a buck power conversion module, a DC contactor 1, a rectifier-inverter module, a boost power conversion module and a capacitor group. The other side of the DC voltage stabilizing module is connected to the electric energy integration module. The buck power conversion module, the boost power conversion module and the capacitor group are all connected in parallel with the DC side of the DC bus on the rear side of the electric energy integration module. The rectifier side of the buck power conversion module is connected in parallel with the rectifier side of the boost power conversion module. The rectifier side of the buck power conversion module is connected to the rectifier-inverter module through a DC contactor 1. The rectifier side of the boost power conversion module is connected to the rectifier-inverter module through a DC contactor. The rectifier side of the boost power conversion module is connected to the rectifier-inverter module through a DC contactor. The rectifier-inverter module is connected to the variable frequency motor through three-phase AC power.

[0012] Preferably, the heat dissipation system includes a heat dissipation pump, a heat dissipation motor and a compressor motor. One oil outlet of the heat dissipation pump is connected to the two oil outlets of the heat dissipation motor through a reversing valve and a pressure compensation valve 2. The heat dissipation motor is coaxially connected to the variable frequency motor, and the output end of the variable frequency motor is connected to the fan; another oil outlet of the heat dissipation pump is connected to the oil inlet of the compressor motor through a pressure compensation valve 1. The oil outlet of the compressor motor is connected to the hydraulic oil tank, and the motor is coaxially connected to the heat dissipation pump through a motor clutch.

[0013] Preferably, a shuttle valve 2 is provided between the two oil ports of the heat dissipation motor, a shuttle valve 1 is provided between the output end of the shuttle valve 2 and the input oil port of the compressor motor, and the output oil port of the shuttle valve 1 acts on the control oil ports of the pressure compensation valve 1, the pressure compensation valve 2 and the heat dissipation pump.

[0014] Preferably, the working system includes a main valve, a main pump and an engine. The engine is coaxially connected to the main pump through an engine clutch. The main pump is also coaxially connected to the cooling pump. The oil outlet of the main pump is connected to the oil inlet of the main valve, and the working oil port of the main valve is connected to the hydraulic actuator.

[0015] Preferably, the oil return system includes a hydraulic oil tank, a radiator, a bypass valve and a back pressure valve. The oil return port of the main valve is connected to the hydraulic oil tank through the back pressure valve and the radiator. The back pressure valve and the radiator are connected in series and then in parallel with the bypass valve.

[0016] A control method adopts the dual-power excavator hydraulic system as described in any one of the above, including a fuel mode and an electric mode.

[0017] Preferably, the control method of the fuel mode is:

[0018] The engine clutch is energized and the motor clutch is de-energized, so that the engine is coaxially connected with the cooling pump and the main pump, providing motive power for the main pump and the cooling pump. The motor is disconnected from the cooling pump, and the hydraulic oil output from the main pump is delivered to the hydraulic actuator through the internal flow channel and logic control of the main valve; the return oil of the main valve returns to the hydraulic oil tank through the back pressure valve and the radiator, or returns to the hydraulic oil tank through the bypass valve; the cooling pump outputs hydraulic oil to drive the compressor motor and the cooling motor at the same time, and the compressor motor drives the compressor to work for air conditioning and refrigeration. The cooling motor is coaxially connected with the variable frequency motor, and the variable frequency motor is connected to the fan to drive the fan to rotate to dissipate heat for the radiator; the controller changes the torque size and direction of the variable frequency motor through the variable frequency control cabinet according to the electrical energy capacity on the DC bus, thereby controlling whether the variable frequency motor is in the electric state or the power generation state;

[0019] When the electric energy on the DC bus does not meet the set value, the controller sends a control signal to the frequency conversion control cabinet, and the torque direction of the frequency conversion motor is changed by the DTC torque control algorithm through the drive circuit inside the frequency conversion control cabinet to make it in the power generation state. The three-phase AC power emitted is rectified into DC power by the rectifier-inverter module. At this time, if the voltage value emitted is higher than the voltage value on the DC bus, the DC contactor 1 is closed and the DC contactor 2 is disconnected. The rectified DC power is stepped down by the step-down power conversion module and transmitted to the DC bus, and the excess energy is stored by the capacitor group; if the voltage value emitted is lower than the voltage value on the DC bus, the DC contactor 1 is disconnected and the DC contactor 2 is closed. The rectified DC power is stepped up by the step-up power conversion module and transmitted to the DC bus, and the excess energy is stored by the capacitor group;

[0020] When the DC bus has sufficient power, the controller sends a control signal to the frequency conversion control cabinet, and the DTC torque control algorithm is used to change the torque direction of the frequency conversion motor through the drive circuit inside the frequency conversion control cabinet to put it in an electric state. At this time, if the voltage value on the DC bus is lower than the voltage value required by the frequency conversion motor, the DC contactor 1 is closed and the DC contactor 2 is disconnected. The DC power of the DC bus is boosted by the step-down power conversion module and inverted into AC power by the rectifier-inverter module to provide power for the frequency conversion motor, and together with the heat dissipation motor, it provides power to drive the fan to rotate, and the capacitor group discharges to supplement the power of the DC bus; at this time, if the voltage value on the DC bus is higher than the voltage value required by the frequency conversion motor, the DC contactor 1 is disconnected and the DC contactor 2 is closed. The DC power of the DC bus is stepped down by the step-up power conversion module and inverted into AC power by the rectifier-inverter module to provide power for the frequency conversion motor, and together with the heat dissipation motor, it provides power to drive the fan to rotate, and the capacitor group discharges to supplement the power of the DC bus.

[0021] Preferably, the control method of the electric mode is:

[0022] The engine clutch loses power, and the motor clutch gains power, so that the motor is coaxially connected with the cooling pump and the main pump, providing motive power for the main pump and the cooling pump, and the engine is disconnected from the main pump; the DC power converted from light energy to the DC bus is inverted into AC power through the inverter module to supply the motor; the hydraulic oil output by the main pump is delivered to the hydraulic actuator through the internal flow channel and logic control of the main valve; the return oil of the main valve passes through the back pressure valve and the radiator to return to the hydraulic oil tank, or through the bypass valve to return to the hydraulic oil tank; the cooling pump outputs hydraulic oil to drive the compressor motor and the cooling motor at the same time, and the compressor motor drives the compressor to work for air conditioning and refrigeration, the cooling motor is coaxially connected with the variable frequency motor, and the variable frequency motor is connected to the fan to drive the fan to rotate to dissipate heat for the radiator; the controller changes the torque size and direction of the variable frequency motor through the variable frequency control cabinet according to the electrical energy capacity on the DC bus, thereby controlling whether the variable frequency motor is in the electric state or the power generation state;

[0023] When the electric energy on the DC bus does not meet the set value, the controller sends a control signal to the frequency conversion control cabinet. The drive circuit inside the frequency conversion control cabinet uses the DTC torque control algorithm to change the torque direction of the frequency conversion motor to put it in a power generation state. The three-phase AC power is rectified into DC power by the rectifier-inverter module. If the voltage value emitted at this time is higher than the voltage value on the DC bus, DC contactor 1 is closed and DC contactor 2 is disconnected. The rectified DC power is stepped down by the step-down power conversion module and transmitted to the DC bus. The excess energy is stored by the capacitor bank. If the voltage value emitted is lower than the voltage value on the DC bus, the DC contactor The first contactor is disconnected and the second contactor is closed. The rectified DC power is boosted and processed by the boost power conversion module and transmitted to the DC bus. The excess energy is stored by the capacitor bank. The function of the power integration module is to optimize and adjust the current, voltage and power on the DC bus. The power on the photovoltaic power generation side and the power on the variable frequency motor side can be transmitted to each other according to the actual working conditions, and the power on both sides can be coordinated and controlled to improve the power utilization rate and the coordination of the photovoltaic power generation system. In the electric mode, the power generated by the variable frequency motor is voltage-controlled and power-matched by the power integration module, and then transmitted to the photovoltaic power generation side to provide energy for the motor.

[0024] When the DC bus has sufficient power, the controller sends a control signal to the frequency conversion control cabinet, and then uses the DTC torque control algorithm through the drive circuit inside the frequency conversion control cabinet to change the torque direction of the frequency conversion motor to put it in an electric state. At this time, if the voltage value on the DC bus is lower than the voltage value required by the frequency conversion motor, DC contactor 1 is closed and DC contactor 2 is disconnected. The DC power of the DC bus is boosted by the step-down power conversion module and inverted into AC power by the rectifier-inverter module to provide power for the frequency conversion motor, and together with the heat dissipation motor, it provides power to drive the fan to rotate, and the capacitor bank discharges to the DC The electric energy of the bus is replenished; at this time, if the voltage value on the DC bus is higher than the voltage value required by the variable frequency motor, DC contactor 1 is disconnected and DC contactor 2 is closed, and the DC power of the DC bus is stepped down by the boost power conversion module and inverted into AC power by the rectifier-inverter module to provide power for the variable frequency motor, and together with the cooling motor, it provides power to drive the fan to rotate, and the capacitor group discharges to replenish the electric energy of the DC bus; at the same time, the electric energy on the photovoltaic power generation side is voltage-controlled and electric power-matched by the power integration module, and is transmitted to the variable frequency motor side to provide energy, or stored in the capacitor group.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. Through the motor clutch and the engine clutch (two electromagnetic clutches), the engine clutch is connected between the main pump and the engine, and the motor clutch is connected between the motor and the cooling pump. The opening and closing states of the two electromagnetic clutches are controlled by the controller to switch between the fuel mode and the electric mode; therefore, only one set of main pumps and one set of pipelines are needed to achieve dual power output, reducing design and production costs, simplifying pipelines, and saving space;

[0027] 2. The present invention uses light energy as energy input and designs a light energy power supply system to convert light energy into electrical energy to provide power for the excavator system. Light energy is a renewable energy source that is clean, environmentally friendly, pollution-free, safe and reliable, greatly reducing the user's operating and maintenance costs. At the same time, the light energy power supply system designed by the present invention is not incorporated into the power grid and will not have any impact on the national power grid or other influences.

[0028] 3. The solar power supply system and electric power transmission system designed by the present invention include a DC voltage stabilizing module, an electric power integration module, a power conversion module, an energy storage device and a capacitor bank, which can effectively utilize the transmission of light energy and electric energy, improve energy utilization, the coordination of energy transmission, and ensure the reliable and stable operation of the solar power supply system and the electric power transmission system;

[0029] 4. Through the combination of shuttle valve and pressure compensation valve to form a hydraulic circuit, and through the reasonable design of the displacement ratio of the heat dissipation motor and the compressor motor, a heat dissipation pump can simultaneously drive the heat dissipation motor and the compressor motor to work normally, and the flow distribution will not be affected by the increase or decrease of the load;

[0030] 5. The present invention uses a heat dissipation motor to drive a variable frequency motor to generate electricity for power transmission. Since the heat dissipation motor has a small speed range and small fluctuation, the energy generated is stable, the impact on the light power supply system and the electric power transmission system is small, and the adjustment is easy;

[0031] In summary, the two power sources of the present invention provide power to the hydraulic system through only one main pump, which reduces costs, simplifies pipelines, enhances reliability, and saves space. When there is an external power source, the motor is used as the power source to complete the operation, and the engine is used for transportation and auxiliary operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the hydraulic principle diagram of the present invention;

[0033] Figure 2 Schematic diagram of the four-quadrant operation of the variable frequency motor in the present invention;

[0034] Figure 3 Schematic diagram of the power generation working condition of the variable frequency motor in the present invention;

[0035] Figure 4 It is a schematic diagram of the electric working condition of the variable frequency motor in the present invention;

[0036] Figure 5 It is a schematic diagram of energy flow in the present invention;

[0037] Figure 6 It is a schematic diagram of the control method in the present invention;

[0038] Figure 7 It is a schematic diagram of a dual-power main pump oil supply system in the prior art.

[0039] In the figure: 1. Concentrator; 2. Solar cell group; 3. Converging device; 4. LCL filter; 5. DC voltage regulator module; 6. Energy storage device; 7. Photoelectric contactor; 8. Inverter module; 9. Power integration module; 10. Frequency conversion control cabinet; 11. Buck power conversion module; 12. DC contactor 1; 13. Rectifier-inverter module; 14. DC contactor 2; 15. Boost power conversion module; 16. Capacitor group; 17. Hydraulic oil tank; 18. Radiator; 19. Bypass valve ; 20. Back pressure valve; 21. Fan; 22. Air conditioning compressor; 23. Compressor motor; 24. Variable frequency motor; 25. Pressure compensation valve 1; 261. Shuttle valve 1; 262. Shuttle valve 2; 27. Cooling motor; 28. Pressure compensation valve 2; 29. ​​Reversing valve; 30. Hydraulic actuator; 31. Electric motor; 32. Main valve; 33. Controller; 34. Electric motor clutch; 35. Cooling pump; 36. Main pump; 37. Engine clutch; 38. Engine; 39. DC bus. DETAILED DESCRIPTION

[0040] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.

[0041] Embodiment 1:

[0042] like Figure 1 As shown, a dual-power excavator hydraulic system includes a working system, a motor 31, a light power supply system, a heat dissipation system, a variable frequency motor 24 and an electric power transmission system, wherein the light power supply system is connected to the working system through the motor 31, the working system is also connected to the hydraulic actuator 30 and the oil return system respectively, and the electric power transmission system is connected to the heat dissipation system through the variable frequency motor 24. The hydraulic actuator 30 includes a boom cylinder, a bucket cylinder, a dipper rod cylinder, a slewing motor, a travel motor, etc.

[0043] Embodiment 2:

[0044] A dual-power excavator hydraulic system, which is different from Example 1 in that the light energy power supply system includes a concentrator 1 for concentrating light sources, a solar cell group 2 for generating direct current, a confluence device 3, a direct current voltage stabilizing module 5, an energy storage device 6 and an inverter module 8 for outputting three-phase alternating current. In this embodiment, the light source (sunlight or other irradiation light source) collects the emitted light through the concentrator 1, irradiates the solar cell group 2 to generate direct current, and is connected to the confluence device 3 through the direct current bus 39. The confluence device 3 is also electrically connected to the direct current voltage stabilizing module 5 through an LCL filter 4. One side of the direct current voltage stabilizing module 5 is connected to the input port of the energy storage device 6, and the energy storage device 6 is connected in parallel with the direct current bus 39 through a light energy contactor 7; the input end of the inverter module 8 is connected in parallel with the direct current side of the direct current bus 39, and the output end of the inverter module 8 is three-phase alternating current connected to the motor 31.

[0045] Furthermore, the electric energy transmission system includes an electric energy integration module 9, a buck power conversion module 11, a DC contactor 12, a rectifier-inverter module 13, a boost power conversion module 15 and a capacitor group 16. The other side of the DC voltage stabilizing module 5 is connected to the electric energy integration module 9. The buck power conversion module 11, the boost power conversion module 15 and the capacitor group 16 are all connected in parallel with the DC side of the DC bus 39 on the rear side of the electric energy integration module 9. The rectifier side of the buck power conversion module 11 is connected in parallel with the rectifier side of the boost power conversion module 15. The rectifier side of the buck power conversion module 11 is connected to the rectifier-inverter module 13 through the DC contactor 12. The rectifier side of the boost power conversion module 15 is connected to the rectifier-inverter module 13 through the DC contactor 14. The rectifier-inverter module 13 is connected to the variable frequency motor 24 through three-phase AC power.

[0046] Furthermore, the heat dissipation system includes a heat dissipation pump 35, a heat dissipation motor 27 and a compressor motor 23. One oil outlet of the heat dissipation pump 35 is connected to the two oil outlets of the heat dissipation motor 27 through a reversing valve 29 and a pressure compensation valve 28. The heat dissipation motor 27 is coaxially connected to the variable frequency motor 24, and the output end of the variable frequency motor 24 is connected to the fan 21; another oil outlet of the heat dissipation pump 35 is connected to the oil inlet of the compressor motor 23 through a pressure compensation valve 25, and the oil outlet of the compressor motor 23 is connected to the hydraulic oil tank 17, and the motor 31 is coaxially connected to the heat dissipation pump 35 through a motor clutch 34.

[0047] Furthermore, a shuttle valve 262 is provided between the two oil ports of the heat dissipation motor 27, a shuttle valve 1 261 is provided between the output end of the shuttle valve 262 and the input oil port of the compressor motor 23, and the output oil port of the shuttle valve 1 261 acts on the control oil ports of the pressure compensation valve 1 25, the pressure compensation valve 2 28 and the heat dissipation pump 35.

[0048] Furthermore, the working system includes a main valve 32, a main pump 36 and an engine 38, wherein the engine 38 is coaxially connected to the main pump 36 via an engine clutch 37, the main pump 36 is also coaxially connected to the heat dissipation pump 35, the oil outlet of the main pump 36 is connected to the oil inlet of the main valve 32, and the working oil port of the main valve 32 is connected to the hydraulic actuator 30. Among them, the motor clutch 34 and the engine clutch 37 are both electromagnetic clutches.

[0049] Furthermore, the oil return system includes a hydraulic oil tank 17, a radiator 18, a bypass valve 19 and a back pressure valve 20. The oil return port of the main valve 32 is connected to the hydraulic oil tank 17 through the back pressure valve 20 and the radiator 18. The back pressure valve 20 and the radiator 18 are connected in series and then connected in parallel with the bypass valve 19.

[0050] Embodiment 3:

[0051] pass Figure 1 and Figure 6 As shown, the light source focuses light energy through the concentrator 1 and acts on the solar cell group 2 to reduce the dispersion of the light source, improve the energy density and the output power of the solar cell group 2. The solar cell group 2 converts the light energy into direct current, which is converged through the converging device 3 and connected to the direct current bus 39; the LCL filter 4 eliminates high-order harmonics and maintains the harmonic content at an extremely low level, so that the voltage and current on the direct current bus 39 are in a stable state and are not affected by the fluctuations generated after the solar energy generates electricity. The voltage is increased by the direct current voltage stabilizing module 5, and the energy storage system composed of a bidirectional DC / DC converter and parallel energy storage elements can realize the recovery and reuse of direct current power, improve the stability and power utilization rate of the direct current power system, and ensure that the voltage on the direct current bus 39 is not affected by load changes. When the light is sufficient, the photovoltaic system provides energy to the AC load, and the remaining energy of the photovoltaic system is transmitted to the converter. When the light is insufficient, the energy provided by the photovoltaic array to the AC load is insufficient, and the battery supplies energy to the AC load through the converter. After the above process, the light energy is converted into stable direct current and stabilized on the direct current bus 39.

[0052] A control method adopts the dual-power excavator hydraulic system as described in the above-mentioned embodiment 1 or embodiment 2. Since this system is a dual-power mode, it is divided into a fuel mode and an electric mode.

[0053] The control method of the fuel mode is:

[0054] The engine clutch 37 is powered, and the motor clutch 34 is powered off, so that the engine 38 is coaxially connected with the cooling pump 35 and the main pump 36, providing motive power for the main pump 36 and the cooling pump 35, and the motor 31 is disconnected from the cooling pump 35, and the hydraulic oil output from the main pump 36 is delivered to the hydraulic actuator 30 through the internal flow channel and logic control of the main valve 32; the return oil of the main valve 32 returns to the hydraulic oil tank 17 through the back pressure valve 20 and the radiator 18, or returns to the hydraulic oil tank 17 through the bypass valve 19; the cooling pump 35 outputs hydraulic oil and drives the compressor motor 23 and the cooling motor 27 at the same time, and the compressor motor 23 drives the compressor to work for air conditioning and refrigeration, and the cooling motor 27 is coaxially connected with the variable frequency motor 24, and the variable frequency motor 24 is connected to the fan 21 to drive the fan to rotate to dissipate heat for the radiator 18; the controller 33 outputs a control signal through the variable frequency control cabinet 10 according to the electric energy capacity on the DC bus 39 to change the torque size and direction of the variable frequency motor 24, thereby controlling whether the variable frequency motor 24 is in the electric state or the power generation state;

[0055] When the electric energy on the DC bus 39 does not meet the set value, the controller 33 sends a control signal to the frequency conversion control cabinet 10, and the torque direction of the frequency conversion motor 24 is changed by the DTC torque control algorithm through the drive circuit inside the frequency conversion control cabinet 10 to make it in a power generation state. The three-phase AC power emitted is rectified into DC power by the rectifier-inverter module 13. At this time, if the voltage value emitted is higher than the voltage value on the DC bus 39, the DC contactor 1 12 is closed and the DC contactor 2 14 is disconnected. The rectified DC power is stepped down by the step-down power conversion module 11 and transmitted to the DC bus 39, and the excess energy is stored by the capacitor group 16; if the voltage value emitted is lower than the voltage value on the DC bus 39, the DC contactor 1 12 is disconnected and the DC contactor 2 14 is closed. The rectified DC power is stepped up by the step-up power conversion module 15 and transmitted to the DC bus 39, and the excess energy is stored by the capacitor group 16;

[0056] When the DC bus 39 has sufficient power, the controller 33 sends a control signal to the frequency conversion control cabinet 10, and the drive circuit inside the frequency conversion control cabinet 10 uses the DTC torque control algorithm to change the torque direction of the variable frequency motor 24 to put it in an electric state. At this time, if the voltage value on the DC bus 39 is lower than the voltage value required by the variable frequency motor 24, the DC contactor 12 is closed and the DC contactor 2 14 is disconnected. The DC power of the DC bus 39 is boosted by the step-down power conversion module 11 and inverted into AC power by the rectifier-inverter module 13 to provide power for the variable frequency motor 24 and the heat dissipation motor 24. The capacitor group 16 discharges to supplement the electric energy of the DC bus 39; at this time, if the voltage value on the DC bus 39 is higher than the voltage value required by the variable frequency motor 24, the DC contactor 12 is disconnected and the DC contactor 2 is closed. The DC power of the DC bus 39 is stepped down by the boost power conversion module 15 and inverted into AC power by the rectifier-inverter module 13 to provide electric energy for the variable frequency motor 24, and the heat dissipation motor 27 provides power to drive the fan 21 to rotate, and the capacitor group 16 discharges to supplement the electric energy of the DC bus 39.

[0057] The heat dissipation pump 35 outputs hydraulic oil to drive the compressor motor 23 and the heat dissipation motor 27 at the same time. By reasonably determining the displacement ratio of the two motors and the pressure compensation effect of the pressure compensation valve 1 25 and the pressure compensation valve 2 28, it is enough to ensure that the two motors can work within the set working speed range and the change of the speed of the two motors will not be affected by load fluctuations. Because both the compressor motor 23 and the heat dissipation motor 27 have their own working speed ranges, the displacements of the two motors also have a corresponding relationship. In this embodiment, it is assumed that the operating speed range of the compressor motor 23 and the heat dissipation motor 27 is 1000r / min-1200r / min, so the displacement of the compressor motor 23 and the heat dissipation motor 27 is set equal (the displacement relationship of the two motors can be redistributed according to actual work requirements). When the loads of the compressor motor 23 and the heat dissipation motor 27 are the same, the hydraulic oil output by the heat dissipation pump 35 can be evenly distributed to the compressor motor 23 and the heat dissipation motor 27, and the two motors rotate at the same speed; if the speed of the fan 21 needs to be increased due to the increase in the temperature of the hydraulic oil, that is, the load of the heat dissipation motor 27 becomes larger, the loads of the compressor motor 23 and the heat dissipation motor 27 are different, and the hydraulic oil output by the heat dissipation pump 35 will flow to the side with lower load, and at this time, all will flow to the compressor motor 23. In this embodiment, a pressure compensation valve and a shuttle valve are added to the front end of the compressor motor 23 and the heat dissipation motor 27 to avoid the result of uneven flow distribution caused by different loads. The same heat dissipation pump 35 can supply oil to the two motors and can work within their respective speed ranges without causing flow imbalance due to different load sizes of the two motors. When the electromagnet at the lower end of the reversing valve 29 is energized and works in the lower position, the hydraulic oil output by the heat dissipation pump 35 passes through the lower position of the reversing valve 29 to the A port of the heat dissipation motor 27, and the hydraulic oil at the B port of the heat dissipation motor 27 returns to the hydraulic oil tank 17 through the lower position of the reversing valve 29; at the same time, the hydraulic oil output by the heat dissipation pump 35 passes through the pressure compensation valve 25 to the oil inlet of the compressor motor 23, and the oil outlet returns to the hydraulic oil tank 17, so that the heat dissipation pump 35 drives the heat dissipation motor 27 and the compressor motor 23 to rotate, and the two motors respectively drive the fan 21 to dissipate heat and the air-conditioning compressor 22 to cool. Assuming that the oil temperature rises during operation and the speed of the fan 21 needs to be increased, the cooling motor 27 needs to provide a larger torque, that is, the load of the cooling motor 27 increases. In order to ensure that the flow distribution ratio of the cooling motor 27 and the compressor motor 23 remains unchanged, the maximum system pressure, that is, the pressure of port A of the cooling motor 27, is obtained through shuttle valve 1 261 and shuttle valve 2 262, which act on the left oil port of the pressure compensation valve 1 25 and the upper oil port of the pressure compensation valve 2 28 respectively; the pressure oil output by the cooling pump 35 acts on the right oil port of the pressure compensation valve 1 25 and the lower oil port of the pressure compensation valve 2 28 respectively.Due to the pressure difference at both ends of the pressure compensation valve, the valve core of the pressure compensation valve 1 25 as a low-pressure compensation valve will move rightward, reducing the opening area of ​​the pressure compensation valve 1 25 until the oil port pressure at the right end of the pressure compensation valve 1 25 is balanced with the maximum pressure of the system; the valve core of the pressure compensation valve 2 28 as the maximum load compensation valve moves upward to increase the opening. At the same time, after the load pressure increases, the maximum pressure of the system will also act on the variable mechanism of the heat dissipation pump 35, so that the displacement of the heat dissipation pump 35 increases to compensate for the flow of the system. The same applies to the reversal of the heat dissipation motor 27 (oil inlet at port B) and the increase in the load of the compressor motor 23.

[0058] The control method of the electric mode is:

[0059] The engine clutch 37 loses power, and the motor clutch 34 gains power, so that the motor 31 is coaxially connected with the cooling pump 35 and the main pump 36, providing motive power for the main pump 36 and the cooling pump 35, and the engine 38 is disconnected from the main pump 36; the direct current converted from light energy to the direct current bus 39 is inverted into alternating current through the inverter module 8 to supply the motor 31; the hydraulic oil output by the main pump 36 is delivered to the hydraulic actuator 30 through the internal flow channel and logic control of the main valve 32; the return oil of the main valve 32 returns to the hydraulic oil tank 17 through the back pressure valve 20 and the radiator 18, or through the bypass valve 19 returns to the hydraulic oil tank 17; the heat dissipation pump 35 outputs hydraulic oil and drives the compressor motor 23 and the heat dissipation motor 27 at the same time. The compressor motor 23 drives the compressor to work for air conditioning and refrigeration. The heat dissipation motor 27 is coaxially connected with the variable frequency motor 24. At the same time, the variable frequency motor 24 is connected to the fan 21 to drive the fan 21 to rotate to dissipate heat for the radiator 18; the controller 33 outputs a control signal through the variable frequency control cabinet 10 according to the power capacity on the DC bus 39 to change the torque size and direction of the variable frequency motor 24, thereby controlling whether the variable frequency motor 24 is in the electric state or the power generation state;

[0060] When the electric energy on the DC bus 39 does not meet the set value, the controller 33 sends a control signal to the frequency conversion control cabinet 10, and the torque direction of the frequency conversion motor 24 is changed by the DTC torque control algorithm through the drive circuit inside the frequency conversion control cabinet 10 to put it in a power generation state. The three-phase AC power emitted is rectified into DC power by the rectifier-inverter module 13. At this time, if the voltage value emitted is higher than the voltage value on the DC bus 39, the DC contactor 12 is closed and the DC contactor 2 14 is disconnected. The rectified DC power is stepped down by the step-down power conversion module 11 and transmitted to the DC bus 39. The excess energy is stored by the capacitor group 16. If the voltage value emitted is lower than the voltage value on the DC bus 39, the DC contactor 1 is closed and the DC contactor 2 is disconnected. The DC power after rectification is stepped down by the step-down power conversion module 11 and transmitted to the DC bus 39. The excess energy is stored by the capacitor group 16. The DC contactor 12 is disconnected and the DC contactor 2 14 is closed. The rectified DC power is boosted by the boost power conversion module 15 and transmitted to the DC bus 39. The excess energy is stored by the capacitor group 16. The function of the power integration module 9 is to optimize and adjust the current, voltage and power on the DC bus 39. The power on the photovoltaic power generation side and the power on the variable frequency motor 24 side can be transmitted to each other according to the actual working conditions, and the power on both sides can be coordinated and controlled to improve the power utilization rate and the coordination of the photovoltaic power generation system. In the electric mode, the power generated by the variable frequency motor 24 is voltage-controlled and power-matched by the power integration module 9, and then transmitted to the photovoltaic power generation side to provide energy for the motor 31.

[0061] When the DC bus 39 has sufficient power, the controller 33 sends a control signal to the frequency conversion control cabinet 10, and then the drive circuit inside the frequency conversion control cabinet 10 uses the DTC torque control algorithm to change the torque direction of the variable frequency motor 24 to put it in an electric state. At this time, if the voltage value on the DC bus 39 is lower than the voltage value required by the variable frequency motor 24, the DC contactor 12 is closed and the DC contactor 2 14 is disconnected. The DC power of the DC bus 39 is boosted by the step-down power conversion module 11 and inverted into AC power by the rectifier-inverter module 13 to provide power for the variable frequency motor 24, and together with the heat dissipation motor 27, it provides power to drive the fan 21 to rotate, and the capacitor group 16 discharges to The electric energy of the DC bus 39 is supplemented; at this time, if the voltage value on the DC bus 39 is higher than the voltage value required by the variable frequency motor 24, the DC contactor 1 12 is disconnected and the DC contactor 2 14 is closed, and the DC power of the DC bus 39 is stepped down by the boost power conversion module 15 and inverted into AC power by the rectifier-inverter module 13 to provide electric energy for the variable frequency motor 24, and together with the heat dissipation motor 27, it provides power to drive the fan 21 to rotate, and the capacitor group 16 discharges to supplement the electric energy of the DC bus 39; at the same time, the electric energy on the photovoltaic power generation side is voltage-controlled and electric power-matched by the electric energy integration module 9, and is transmitted to the variable frequency motor side to provide energy, or stored in the capacitor group 16.

[0062] like Figure 2The figure shows a schematic diagram of the four-quadrant operation of the variable frequency motor, where the horizontal axis represents the motor torque and the vertical axis represents the motor speed. When the variable frequency motor 24 is in the first quadrant, the motor speed and torque are in the same direction, and the variable frequency motor 24 is in the motoring state; when the variable frequency motor 24 is in the second quadrant, the motor speed and torque are in opposite directions, and the variable frequency motor 24 is in the power generation state; when the variable frequency motor 24 is in the third quadrant, the motor speed and torque are in opposite directions, and the variable frequency motor 24 is in the power generation state; when the variable frequency motor 24 is in the fourth quadrant, the motor speed and torque are in the same direction, and the variable frequency motor 24 is in the motoring state.

[0063] like Figure 3 The figure shows a schematic diagram of the power generation condition of the variable frequency motor. The solar power supply system sends AC power to the motor 31. The controller 33 controls the electromagnetic clutch to be energized. The motor 31 drives the cooling pump 35 to work. The cooling pump 35 outputs hydraulic oil to supply the cooling motor 27. The cooling motor 27 is coaxially connected to the variable frequency motor 24 and the fan 21. At this time, the controller 33 controls the motor torque direction to be opposite to the motor rotation direction. The variable frequency motor 24 generates electricity and feeds back to the electric energy transmission system.

[0064] like Figure 4 The figure shows a schematic diagram of the electric working condition of the variable frequency motor. The solar power supply system sends AC power to the motor 31. The controller 33 controls the electromagnetic clutch to be energized. The motor 31 drives the cooling pump 35 to work. The cooling pump 35 outputs hydraulic oil to supply the cooling motor 27. The cooling motor 27 is coaxially connected to the variable frequency motor 24 and the fan 21. At this time, the controller 33 controls the motor torque direction to be connected with the motor rotation direction. The variable frequency motor 24 obtains electric energy from the electric energy transmission system and drives the fan 21 together with the cooling motor 27.

[0065] like Figure 5The diagram shows the energy flow diagram of the present invention. There are four energy forms in the system, namely, light energy, electric energy, hydraulic energy and mechanical energy. The system uses light energy as input, converts it into electric energy through relevant components, and uses electric energy as output and performs feedback and recycling. Light energy transmission process: the light source is concentrated by the concentrator 1, converted into electric energy through the solar cell group 2 and transmitted to the DC bus 39. The electric energy transmission process is as follows: the DC bus 39 is used as the electric energy input source and is transmitted to the motor 31 through the inverter module 8; at the same time, the variable frequency motor 24 side acts as a generator to feed back the generated electric energy to the DC bus 39 through the rectifier-inverter module 13, and then transmitted to the motor 31 or stored in the capacitor group 16. The mechanical energy transmission process is as follows: the output torque of the drive motor side is transmitted to the main pump 36 through the transmission device such as the coupling; the heat dissipation motor 27 transmits the output torque to the variable frequency motor 24 through the coupling in the form of mechanical energy. The hydraulic energy transmission process is as follows: when the main pump 36 is working, it will output high-pressure oil to the main valve 32 in the form of hydraulic energy, and the heat dissipation pump 35 will transmit the hydraulic energy to the compressor motor 23 and the heat dissipation motor 27. Under the above four energy transmission modes, there are hydraulic energy losses caused by leakage of the hydraulic system and overflow units, mechanical energy losses caused by motor friction and transmission devices such as couplings, and electric energy losses caused by heat generated by the rectifier-inverter module 13 during the electric energy conversion process; these energy losses will be obtained from the power grid.

Claims

1. A dual-power excavator hydraulic system, characterized in that: The invention comprises a working system, an electric motor (31), a light energy power supply system, a heat dissipation system, a variable frequency motor (24) and an electric energy transmission system. The light energy power supply system is connected to the working system via the electric motor (31). The working system is also respectively connected to a hydraulic actuator (30) and an oil return system. The electric energy transmission system is connected to the heat dissipation system via the variable frequency motor (24).

2. The dual-power excavator hydraulic system according to claim 1, characterized in that: The light energy power supply system comprises a concentrator (1) for concentrating light sources, a solar cell group (2) for generating direct current, a concentrator (3), a direct current voltage stabilizing module (5), an energy storage device (6) and an inverter module (8) for outputting three-phase alternating current. The concentrator (1) is connected to the concentrator (3) via the solar cell group (2), the concentrator (3) is also electrically connected to the direct current voltage stabilizing module (5) via an LCL filter (4), one side of the direct current voltage stabilizing module (5) is connected to the input port of the energy storage device (6), and the energy storage device (6) is connected in parallel to a direct current bus (39) via a light energy contactor (7); the input end of the inverter module (8) is connected in parallel to the direct current side of the direct current bus (39), and the output end of the inverter module (8) is connected to the motor (31).

3. The dual-power excavator hydraulic system according to claim 2, characterized in that: The electric energy transmission system comprises an electric energy integration module (9), a step-down power conversion module (11), a DC contactor (12), a rectifier-inverter module (13), a step-up power conversion module (15) and a capacitor group (16); the other side of the DC voltage stabilizing module (5) is connected to the electric energy integration module (9); the step-down power conversion module (11), the step-up power conversion module (15) and the capacitor group (16) are all connected to the DC bus ( 39) the DC side is connected in parallel, the rectifier side of the buck power conversion module (11) is connected in parallel with the rectifier side of the boost power conversion module (15), the rectifier side of the buck power conversion module (11) is connected to the rectifier-inverter module (13) through a DC contactor 1 (12), the rectifier side of the boost power conversion module (15) is connected to the rectifier-inverter module (13) through a DC contactor (14), and the rectifier-inverter module (13) is connected to the variable frequency motor (24) through three-phase AC power.

4. The dual-power excavator hydraulic system according to claim 3, characterized in that: The heat dissipation system comprises a heat dissipation pump (35), a heat dissipation motor (27) and a compressor motor (23); one oil outlet of the heat dissipation pump (35) is connected to two oil outlets of the heat dissipation motor (27) through a reversing valve (29) and a second pressure compensation valve (28); the heat dissipation motor (27) is coaxially connected to a variable frequency motor (24); the output end of the variable frequency motor (24) is connected to a fan (21); the other oil outlet of the heat dissipation pump (35) is connected to an oil inlet of the compressor motor (23) through a first pressure compensation valve (25); the oil outlet of the compressor motor (23) is connected to a hydraulic oil tank (17); and the motor (31) is coaxially connected to the heat dissipation pump (35) through a motor clutch (34).

5. The dual-power excavator hydraulic system according to claim 4, characterized in that: A shuttle valve 2 (262) is also provided between the two oil ports of the heat dissipation motor (27), a shuttle valve 1 (261) is provided between the output end of the shuttle valve 2 (262) and the input oil port of the compressor motor (23), and the output oil port of the shuttle valve 1 (261) acts on the control oil ports of the pressure compensation valve 1 (25), the pressure compensation valve 2 (28) and the heat dissipation pump (35).

6. The dual-power excavator hydraulic system according to any one of claims 1 to 5, characterized in that: The working system comprises a main valve (32), a main pump (36) and an engine (38); the engine (38) is coaxially connected to the main pump (36) via an engine clutch (37); the main pump (36) is also coaxially connected to a heat dissipation pump (35); an oil outlet of the main pump (36) is connected to an oil inlet of the main valve (32); and a working oil port of the main valve (32) is connected to a hydraulic actuator (30).

7. The dual-power excavator hydraulic system according to claim 6, characterized in that: The oil return system comprises a hydraulic oil tank (17), a radiator (18), a bypass valve (19) and a back pressure valve (20); the oil return port of the main valve (32) is connected to the hydraulic oil tank (17) via the back pressure valve (20) and the radiator (18); the back pressure valve (20) and the radiator (18) are connected in series and then connected in parallel to the bypass valve (19).

8. A control method, characterized in that: A dual-power excavator hydraulic system as described in any one of claims 1 to 5 is adopted, comprising a fuel mode and an electric mode.

9. The control method according to claim 8, characterized in that: The control method of the fuel mode is: The engine clutch (37) is energized and the motor clutch (34) is de-energized, so that the engine (38) is coaxially connected with the cooling pump (35) and the main pump (36) to provide motive force for the main pump (36) and the cooling pump (35). The motor (31) is disconnected from the cooling pump (35), and the hydraulic oil output from the main pump (36) is delivered to the hydraulic actuator (30) through the internal flow channel and logic control of the main valve (32); the return oil of the main valve (32) is returned to the hydraulic oil tank (17) through the back pressure valve (20) and the radiator (18), or returned to the hydraulic oil tank (17) through the bypass valve (19); the cooling pump (35) outputs hydraulic oil to drive the compressor motor (23) and the heat dissipation motor (27) at the same time, the compressor motor (23) drives the compressor to work for air conditioning and refrigeration, the heat dissipation motor (27) is coaxially connected with the variable frequency motor (24), and the variable frequency motor (24) is connected with the fan (21) to drive the fan to rotate to dissipate heat for the radiator (18); the controller (33) outputs a control signal through the variable frequency control cabinet (10) according to the electric energy capacity on the DC bus (39) to change the torque size and direction of the variable frequency motor (24), thereby controlling whether the variable frequency motor (24) is in the electric state or the generating state; When the electric energy on the DC bus (39) does not meet the set value, the controller (33) sends a control signal to the frequency conversion control cabinet (10), and the drive circuit inside the frequency conversion control cabinet (10) uses the DTC torque control algorithm to change the torque direction of the frequency conversion motor (24) to put it in a power generation state; When the DC bus (39) has sufficient electric energy, the controller (33) sends a control signal to the frequency conversion control cabinet (10), and the drive circuit inside the frequency conversion control cabinet (10) uses the DTC torque control algorithm to change the torque direction of the frequency conversion motor (24) to put it in an electric state.

10. The control method according to claim 8, characterized in that: The control method of the electric mode is: The engine clutch (37) loses power, and the motor clutch (34) gains power, so that the motor (31) is coaxially connected with the cooling pump (35) and the main pump (36), providing motive power for the main pump (36) and the cooling pump (35), and the engine (38) is disconnected from the main pump (36); the direct current converted from light energy to the direct current bus (39) is inverted into alternating current through the inverter module (8) and supplied to the motor (31); the hydraulic oil output by the main pump (36) is delivered to the hydraulic actuator (30) through the internal flow channel and logic control of the main valve (32); the return oil of the main valve (32) is returned to the hydraulic oil tank (17) through the back pressure valve (20) and the radiator (18), or through the bypass The hydraulic oil is returned to the hydraulic oil tank (17) by the valve (19); the heat dissipation pump (35) outputs hydraulic oil to drive the compressor motor (23) and the heat dissipation motor (27) at the same time; the compressor motor (23) drives the compressor to work to perform air conditioning and refrigeration; the heat dissipation motor (27) is coaxially connected to the variable frequency motor (24); at the same time, the variable frequency motor (24) is connected to the fan (21) to drive the fan (21) to rotate to dissipate heat for the radiator (18); the controller (33) outputs a control signal through the variable frequency control cabinet (10) according to the electric energy capacity on the DC bus (39) to change the torque size and direction of the variable frequency motor (24), thereby controlling whether the variable frequency motor (24) is in an electric state or a power generation state; When the electric energy on the DC bus (39) does not meet the set value, the controller (33) sends a control signal to the frequency conversion control cabinet (10), and the drive circuit inside the frequency conversion control cabinet (10) uses the DTC torque control algorithm to change the torque direction of the frequency conversion motor (24) to put it in a power generation state; When the DC bus (39) has sufficient electrical energy, the controller (33) sends a control signal to the frequency conversion control cabinet (10), and then the drive circuit inside the frequency conversion control cabinet (10) uses a DTC torque control algorithm to change the torque direction of the frequency conversion motor (24) to put it in an electric state.

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