阅读说明：本技术 一种电动液压挖掘机的动力系统 (Power system of electric hydraulic excavator ) 是由 钱勇 刘浩 孙中林 孟庆锋 张宇 仇维蓉 吴洋 严洁银 于 2021-09-03 设计创作，主要内容包括：本发明涉及一种电动液压挖掘机的动力系统,包括：电池驱动系统、交流电驱动系统；电池驱动系统包括：锂电池组,其通过MCU、交流控制箱驱动电机转动；交流电驱动系统包括：交流电源,其通过交流控制箱驱动电机转动的同时,通过MCU向锂电池充电；电机驱动主泵的运动；本装置实现了锂电池与交流电源间的随时切换,从而实现两种能源供给方式的互补,转场、使用方便,续航无限制,充电便利,生产成本、运行维护成本低。(The invention relates to a power system of an electric hydraulic excavator, which comprises: a battery-driven system, an alternating current-driven system; the battery driving system includes: the lithium battery pack drives the motor to rotate through the MCU and the alternating current control box; an alternating current drive system comprising: the alternating current power supply is used for charging the lithium battery through the MCU while driving the motor to rotate through the alternating current control box; the motor drives the main pump to move; the device realizes the switching between the lithium battery and the alternating current power supply at any time, thereby realizing the complementation of two energy supply modes, and having the advantages of convenient transition and use, unlimited endurance, convenient charging, low production cost and low operation and maintenance cost.)

1. A power system for an electro-hydraulic excavator, comprising: a battery-driven system, an alternating current-driven system;

the battery driving system includes:

the lithium battery pack drives the motor to rotate through the MCU and the alternating current control box;

the alternating current drive system comprises:

the alternating current power supply is used for charging the lithium battery pack through the MCU while driving the motor to rotate through the alternating current control box;

the motor drives the motion of the main pump.

2. The power system of the electric hydraulic excavator according to claim 1, wherein the lithium battery pack drives the main pump to move sequentially through the PDU, the MCU, the AC control box, the motor and the coupling;

the alternating current power supply is connected with the motor through the alternating current charging port, the alternating current control box and the coupler, the motor drives the main pump to move, and meanwhile, the alternating current power supply is connected with the lithium battery pack through the alternating current charging port, the alternating current control box, the MCU and the PDU.

3. The power system of an electro-hydraulic excavator according to claim 1 wherein the motor is a three phase asynchronous motor.

4. The power system of an electric hydraulic excavator according to claim 1 wherein the ac control box comprises:

the first branch is connected with the MCU and the first end of the motor, and KM1 is arranged on the first branch;

the second branch is connected with the MCU and the second end of the motor, and KM2 is arranged on the second branch;

the direct current provided by the lithium battery pack is converted into alternating current through the MCU, and the motor is driven to rotate through the first branch and the second branch;

the third branch is connected with the alternating current power supply and the MCU, and KM3 is arranged on the third branch;

the alternating current power supply charges the MCU through the third branch circuit;

the fourth branch is connected with the alternating current power supply and the first end of the motor, and KM4 is arranged on the fourth branch;

the fifth branch is connected with the fourth branch and the second end of the motor, and KM5 is arranged on the fifth branch;

the alternating current power supply supplies power to the motor through the fourth branch and the fifth branch and drives the motor to rotate;

the sixth branch circuit is used for short-circuiting the second end of the motor and is provided with KM 6;

the first end of the motor includes: u1, V1, W1;

the second end of the motor includes: u2, V2, W2.

Technical Field

The invention relates to a power system, in particular to a power system of an electric hydraulic excavator.

Background

At present, the electric hydraulic excavator mainly has two driving modes: 1. the lithium battery is an energy driving motor; 2 alternating current is used as energy to drive the motor. The advantages and disadvantages of both schemes are very obvious: 1. lithium battery: the device has no cable to influence the vehicle operation, is convenient to transfer and use, and basically has no difference with an internal combustion engine; however, the cost is high, the endurance time is limited, the charging pile needs to be built in a certain operation range, the charging time is long, and the construction time is limited; 2. alternating current: the cost is low, the work can be carried out when electricity exists, charging is not needed, the endurance problem is avoided, and the work can be done when electricity exists; but the transition is difficult, and the cable is around the vehicle body when in use.

In conclusion, how to switch between the lithium battery and the alternating current power supply at any time is a problem which needs to be solved urgently by researchers of the company.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: how to realize the switching between the lithium battery and the alternating current power supply at any time;

in order to solve the technical problems, the invention adopts the following technical scheme:

the invention relates to a power system of an electric hydraulic excavator, which comprises: a battery-driven system, an alternating current-driven system; the battery driving system includes: the lithium battery pack drives the motor to rotate through the MCU and the alternating current control box; an alternating current drive system comprising: the alternating current power supply is used for charging the lithium battery through the MCU while driving the motor to rotate through the alternating current control box; the motor drives the main pump to move;

in this scheme, can turn into alternating current driving motor through lithium cell group and rotate to through shaft coupling drive main pump motion, can realize again that the alternating current is direct when passing through the motion of motor drive main pump, charge to the lithium cell through the alternating current.

In order to explain a power system specifically, a lithium battery pack is adopted to drive a main pump to move sequentially through a PDU (Power Unit), an MCU (micro control Unit), an alternating current control box, a motor and a coupling; the alternating current power supply drives the main pump to move through the alternating current charging port, the alternating current control box, the motor and the coupler, and meanwhile, the alternating current power supply charges the lithium battery pack through the alternating current charging port, the alternating current control box, the MCU and the PDU;

in the lithium battery pack line, the lithium battery pack sequentially passes through a PDU (protocol data Unit), an MCU (direct Current-alternating Current), an alternating current control box, a motor and a main pump;

in the alternating current power supply, the alternating current power supply sequentially passes through an alternating current charging port, an alternating current control box, a motor and a main pump, and the alternating current charging port charges a lithium battery pack through the alternating current control box, an MCU (micro control unit) (DC-AC) and a PDU (Power distribution Unit).

Wherein: a lithium battery pack: a lithium battery power supply system; PDU: a direct current high voltage distribution box; MCU: a motor driver; an alternating current control box: switching a power supply, detecting a phase sequence and protecting an alternating current loop; a motor: and the motor system drives the main pump to supply power to the whole machine.

In order to explain the concrete device of the motor, the motor is a three-phase asynchronous motor.

In order to explain the specific circuit layout of the AC control box, the invention adopts the AC control box comprising: the first branch is connected with the MCU and the first end of the motor, and KM1 is arranged on the first branch; the second branch is connected with the MCU and the second end of the motor, and KM2 is arranged on the second branch; direct current provided by the lithium battery pack is converted into alternating current through the MCU, and the motor is driven to rotate through the first branch and the second branch; the third branch is connected with an alternating current power supply and the MCU, and is provided with KM 3; the alternating current power supply charges the MCU through the third branch circuit; the fourth branch is connected with an alternating current power supply and the first end of the motor, and is provided with KM 4; the fifth branch is connected with the fourth branch and the second end of the motor, and KM5 is arranged on the fifth branch; the alternating current power supply supplies power to the motor through the fourth branch and the fifth branch and drives the motor to rotate; the sixth branch is used for short-circuiting the second end of the motor and is provided with KM 6; the first end of the motor includes: u1, V1, W1; the second end of the motor includes: u2, V2, W2;

the power supply system is selected by an operator, when the branch 1 is selected, the VCU is connected with the KM1/KM2 and is disconnected with the KM3/KM4/KM5/KM6, the MCU is directly connected with the motor, the motor is used by converting direct-current high-voltage power into alternating current through the MCU, and the whole machine adopts a lithium battery driving mode.

When branch 2 is selected

If the motor is not started:

the KM1/KM2 is switched on, the KM3/KM4/KM5/KM6 is switched off, the motor is started by using the MCU, when the motor runs to 1400 revolutions, the KM1/KM2 is switched off, the KM6 is kept off, the KM3/KM4/KM5 is attracted, and the motor enters a power frequency running state (soft start).

If the motor is in operation:

and controlling the rotating speed of the motor to 1400 revolutions, disconnecting the KM1/KM2, keeping the KM6 disconnected, attracting the KM3/KM4/KM5, and enabling the motor to enter a power frequency running state MCU to enter a feedback system to charge the battery. At the moment, the VCU calculates the feedback current according to the rated power, calculates the feedback current value in real time and ensures that the requirement on the power grid is kept in the rated load.

If the MCU has a fault, star-delta voltage reduction starting can be realized through KM4/KM5/KM6, and the motor is started for use.

The VCU is a vehicle control unit, the branch circuit 1 is a direct current power supply circuit, and the branch circuit 2 is an alternating current power supply circuit.

The invention has the beneficial effects that: the invention relates to a power system of an electric hydraulic excavator, which realizes the switching between a lithium battery and an alternating current power supply at any time, thereby realizing the complementation of two energy supply modes, and has the advantages of convenient transition and use, unlimited endurance, convenient charging, low production cost and low operation and maintenance cost.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a circuit diagram of an AC control box;

in the figure: the system comprises a 1-lithium battery pack, a 2-3-MCU, a 4-alternating current control box, a 5-motor, a 6-main pump, a 7-alternating current power supply, an 8-alternating current charging port, a 11-first branch, a 12-second branch, a 13-third branch, a 14-fourth branch, a 15-fifth branch and a 16-sixth branch.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.

As shown in fig. 1, the present invention is a power system of an electric hydraulic excavator, including: a battery-driven system, an alternating current-driven system; the battery driving system includes: the lithium battery pack 1 drives the motor 5 to rotate through the MCU3 and the alternating current control box 4; an alternating current drive system comprising: the alternating current power supply 7 is used for driving the motor 5 to rotate through the alternating current control box 4 and simultaneously charging the lithium battery pack 1 through the MCU 3; the motor 5 drives the main pump 6 to move;

in this scheme, can turn into alternating current driving motor through lithium cell group and rotate to through shaft coupling drive main pump motion, can realize again that the alternating current is direct when passing through the motion of motor drive main pump, charge to the lithium cell through the alternating current.

As shown in fig. 1, in order to specifically explain a power system, the lithium battery pack 1 is adopted to drive a main pump 6 to move sequentially through a PDU2, an MCU3, an ac control box 4, a motor 5 and a coupling; while the alternating current power supply 7 drives the main pump 6 to move through the alternating current charging port 8, the alternating current control box 4, the motor 5 and the coupler, the alternating current power supply 7 charges the lithium battery pack 1 through the alternating current charging port 8, the alternating current control box 4, the MCU3 and the PDU 2;

in the lithium battery pack line, the lithium battery pack sequentially passes through a PDU (protocol data Unit), an MCU (direct Current-alternating Current), an alternating current control box, a motor and a main pump;

in the alternating current power supply, while the alternating current power supply sequentially passes through the alternating current charging port 8, the alternating current control box 4, the motor 5 and the main pump 6, the alternating current charging port 8 charges the lithium battery pack 1 through the alternating current control box 4, the MCU (DC-AC)3 and the PDU 2.

Wherein: a lithium battery pack: a lithium battery power supply system; PDU: a direct current high voltage distribution box; MCU: a motor driver; an alternating current control box: switching a power supply, detecting a phase sequence and protecting an alternating current loop; a motor: and the motor system drives the main pump to supply power to the whole machine.

As shown in fig. 1, in order to illustrate a specific device of the motor, the motor 5 is a three-phase asynchronous motor.

As shown in fig. 2, in order to explain a specific circuit layout of the ac control box, the present invention employs an ac control box including: the first branch 11 is connected with the MCU3 and the first end of the motor 5, and is provided with KM 1; the second branch 12 is connected with the MCU3 and the second end of the motor 5, and is provided with KM 2; direct current provided by the lithium battery pack 1 is converted into alternating current through the MCU3, and the motor is driven to rotate through the first branch circuit 11 and the second branch circuit 12; a third branch 13 connected with an alternating current power supply 7 and an MCU3, and provided with a KM 3; the alternating current power supply 7 charges the MCU3 through the third branch 13; a fourth branch 14, which is connected to the ac power supply 7 and the first end of the motor 5, and on which KM4 is disposed; a fifth branch 15, which is connected to the fourth branch 14 and the second end of the motor 5, and on which KM5 is disposed; the alternating current power supply 7 supplies power to the motor 5 through the fourth branch 14 and the fifth branch 15 and drives the motor 5 to rotate; a sixth branch 16, which short-circuits the second end of the motor 5 and on which KM6 is arranged; the first end of the motor 5 comprises: u1, V1, W1; the second end of the motor 5 comprises: u2, V2, W2;

the power supply system is selected by an operator, when the branch 1 is selected, the VCU is connected with the KM1/KM2 and is disconnected with the KM3/KM4/KM5/KM6, the MCU is directly connected with the motor, the motor is used by converting direct-current high-voltage power into alternating current through the MCU, and the whole machine adopts a lithium battery driving mode.

When branch 2 is selected

If the motor is not started:

the KM1/KM2 is switched on, the KM3/KM4/KM5/KM6 is switched off, the motor is started by using the MCU, when the motor runs to 1400 revolutions, the KM1/KM2 is switched off, the KM6 is kept off, the KM3/KM4/KM5 is attracted, and the motor enters a power frequency running state (soft start).

If the motor is in operation:

and controlling the rotating speed of the motor to 1400 revolutions, disconnecting the KM1/KM2, keeping the KM6 disconnected, attracting the KM3/KM4/KM5, and enabling the motor to enter a power frequency running state MCU to enter a feedback system to charge the battery. At the moment, the VCU calculates the feedback current according to the rated power, calculates the feedback current value in real time and ensures that the requirement on the power grid is kept in the rated load.

If the MCU has a fault, star-delta voltage reduction starting can be realized through KM4/KM5/KM6, and the motor is started for use.

The VCU is a vehicle control unit, the branch circuit 1 is a direct current power supply circuit, and the branch circuit 2 is an alternating current power supply circuit.

The advantage of this patent, 1, lithium cell drive's excavator has the multichannel loss on energy conversion: a. the conversion efficiency of a charger; b. the charge-discharge conversion efficiency of the lithium battery; c. MCU conversion efficiency; when alternating current is used for direct drive, the loss of the three energy sources can be saved, and the economy is better.

2. The excavator is slow to travel, fills electric pile and need follow vehicle operation radius and carry out position control, otherwise the distance of traveling overlength will lead to the operating time to descend indirectly. This patent is as long as remove block terminal, promotes greatly at construction site maneuverability

3. The reliability is improved, when a direct-current high-voltage system fails, the whole machine can be forcibly powered by an alternating-current system, the control system is continuously powered by a lead-acid battery and a switching power supply, so that the vehicle can be withdrawn from a construction position, and the delay of a construction period caused by the fact that the vehicle cannot move is avoided.

4. The 20-ton excavator powered by the lithium battery can continuously work for 8 hours by using more than 500kwh of electric quantity, and needs 3-4 hours when the excavator is fully charged. The operation time is not proportional to the charging time, and the work time cannot be adapted to a scene with a short construction period. By adopting the battery power supply, the battery power supply only needs 150kWh, no external power supply can ensure the whole machine to work for 2h, the working conditions of equipment transition, short-time power failure and the like can be ensured, the adaptability of each scene of the host machine is improved, and the cost of the whole machine is greatly reduced.

The invention relates to a power system of an electric hydraulic excavator, which realizes the switching between a lithium battery and an alternating current power supply at any time, thereby realizing the complementation of two energy supply modes, and has the advantages of convenient transition and use, unlimited endurance, convenient charging, low production cost and low operation and maintenance cost.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.