WO2017080001A1

WO2017080001A1 - Electric transmission system and control method therefor

Info

Publication number: WO2017080001A1
Application number: PCT/CN2015/095612
Authority: WO
Inventors: 董笑辰; 马晨普; 张福景; 赵研; 滕奔
Original assignee: 中车大连电力牵引研发中心有限公司
Priority date: 2015-11-11
Filing date: 2015-11-26
Publication date: 2017-05-18
Also published as: CN106671795A

Abstract

Disclosed are an electric transmission system and a control method therefor, the system comprising: a generator (20) connected to an internal combustion engine (10), a converter (50) connected to a storage battery (60) and an electric motor (30) connected to a system (40) to be driven, wherein the converter (50) is connected to the generator (20) and the electric motor (30) respectively. The converter (50) is used for driving the generator (20) and the electric motor (30) to operate. The generator (20) is used for driving the internal combustion engine (10) to start under the driving of the converter (50), so that the internal combustion engine (10) transmits power to the generator (20) after the internal combustion engine is started. The electric motor (30) is used for driving the system (40) to be driven to start and operate under the driving of the converter (50). The electric transmission system solves the technical problems of a transmission device being easily worn out in an existing mechanical transmission process, the operation being complex and the requirements for an operator being relatively high.

Description

Electric drive system and control method thereof

Technical field

The present invention relates to a transmission system, and more particularly to an electric drive system for a tractor and a control method therefor.

Background technique

With the development of the agricultural economy, the farming methods have gradually shifted from manual operations to mechanized operations. Therefore, the demand for large-scale agricultural machinery equipment is gradually increasing. The traditional agricultural machinery equipment, such as tractors, has mechanical, hydraulic and hydraulic transmission systems. Among them, mechanical transmission systems are the most widely used.

At present, the mechanical transmission system mainly includes: a power output mechanism (such as a diesel engine), a transmission clutch mechanism (including a clutch), a shifting mechanism (including a gearbox), and a rotating plane direction mechanism, and is supplemented with a necessary coupling mechanism and The speed reduction mechanism (reduction box), when running, firstly, after the power output of the diesel engine is transmitted to the clutch through the power output shaft, when the clutch is combined, the power is transmitted to the gearbox through the clutch, and when the gearbox is engaged, the power is transmitted to the gearbox. The central transmission shaft is then transmitted to the left and right driving wheels by the central transmission shaft, which is divided into one or more stages on the left and right sides or one or more speed reduction boxes.

However, in the existing transmission system, there is a complicated mechanical transmission system from the power output shaft to the drive wheel, including frequent operation processes such as operating the clutch, switching the gear position, and controlling the brake. When the operator is not operating properly, it is extremely easy. The result is abnormal wear of the equipment, frequent flameout of the diesel engine, waste of fuel, etc., and the driving of the vehicle is complicated, and the requirements for the operator are high.

Summary of the invention

The invention provides an electric drive system and a control method thereof, which solves the technical problem that the transmission device is easy to wear, complicated in operation and high in requirements on the operator in the prior mechanical transmission process.

The invention provides an electric drive system comprising:

a generator connected to the internal combustion engine, a converter connected to the battery, and an electric motor connected to the system to be driven, wherein the converter is respectively connected to the generator and the motor;

The converter is configured to drive the generator and the generator to operate, the generator is configured to drive the internal combustion engine to start under the driving of the converter, so that the internal combustion engine starts to generate electricity The machine transmits power, and the engine is used to drive the to-be-driven system to start operation under the driving of the converter.

In a specific embodiment of the present invention, the current transformer includes: a first current transformer, a second current transformer, and a third current transformer, wherein the first current transformer is connected to the battery, A second current transformer is coupled to the first current transformer, the third current transformer, and the generator, the third current transformer being coupled to the first current transformer and the electric motor.

In a specific embodiment of the invention, the first converter is a direct current DC-DC converter.

In a specific embodiment of the invention, the second current transformer and the third current transformer are each composed of two insulated gate bipolar transistors IGBTs connected in parallel.

In a specific embodiment of the present invention, the generator and the second converter are connected between the motor and the third converter through a main cable and a signal cable, wherein the The signal cable includes a speed sensor output signal line and a temperature sensor output signal line.

In a specific embodiment of the invention, the generator is a three-phase asynchronous generator, and the motor is a three-phase asynchronous motor.

The invention provides a control method of an electric drive system, wherein the electric drive system is any of the electric drive systems described above, and the control method of the electric drive system comprises:

The converter drives the generator to start according to the start command to drive the internal combustion engine to start;

After the internal combustion engine is started, the generator generates electricity and outputs alternating current under the driving of the internal combustion engine;

The converter converts the alternating current output by the generator into direct current according to a speed control command to drive the motor to start operation.

In a specific embodiment of the present invention, the method further includes: the converter converting the alternating current output by the generator and stepping down the battery for charging.

In a specific embodiment of the present invention, the method further includes: the converter controlling a power generation power of the generator according to a power request instruction.

The invention provides an electric drive system, which is connected to an internal combustion engine via a generator. The converter is connected to a generator, a battery and a motor, and the motor is connected to the system to be driven, so that the converter firstly boosts the voltage of the battery. The generator is started to run, the operation of the generator drives the internal combustion engine to start running, and after the internal combustion engine starts running, the power is output to the generator, so that the generator generates electricity, and the converter converts the output voltage of the generator according to the external speed control command to drive When the motor is running, the operation of the motor drives the system to be driven to operate. During operation, the control of the running speed of the device can be realized only by controlling the rotational speed of the motor, and the rotational speed of the motor is controlled by the pedal connected to the motor. Therefore, the electric drive system In the middle, the process of frequent clutch-shifting in the transmission mechanical transmission system is eliminated, the operation is simpler, and there is no wear between the two main running parts of the generator and the motor, thereby reducing mechanical wear and impact and improving the transmission. Efficiency, therefore, provided by the present invention The electric drive system solves the technical problem that the transmission device is easy to wear, complicated in operation and high in requirements on the operator in the existing mechanical transmission process.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description of the drawings used in the embodiments or the prior art description will be briefly described below. Obviously, the drawings in the following description It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any inventive labor.

1 is a schematic structural view of an electric drive system of the present invention;

2 is another schematic structural view of an electric drive system of the present invention;

Figure 3 is a schematic view showing the connection structure of the converter in the electric drive system of the present invention;

4 is a schematic view showing the connection of a current transformer and a generator in the electric drive system of the present invention;

Figure 5 is a schematic view showing the connection of a current transformer and an electric motor in the electric drive system of the present invention;

6 is a schematic flow chart of a control method of an electric drive system of the present invention;

Fig. 7 is a schematic flow chart showing another control method of the electric drive system of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. It is a partial embodiment of the invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

The electric drive system provided by the embodiment passes the input energy of the generator control system and runs through the motor drive device (such as the tractor), thereby eliminating the clutch-shift process in the conventional mechanical transmission system, and the operation is simpler.

1 is a schematic structural view of an electric drive system of the present invention. As shown in FIG. 1, the electric drive system includes a generator 20 connected to the internal combustion engine 10, a converter 50 connected to the battery 60, and an electric motor connected to the system 40 to be driven. 30, wherein the converter 50 is connected to the generator 20 and the motor 30, respectively. The converter 50 controls the operation of the generator 20 and the motor 30, and the generator 20 is used to drive the internal combustion engine 10 under the driving of the converter 50. In order to start the internal combustion engine 10 to transmit power to the generator 20, that is, the generator 20 is first used to drive the internal combustion engine 10 to start. When the internal combustion engine 10 is started, the internal combustion engine 10 outputs power, and the output power shaft of the internal combustion engine 10 is connected to the generator 20. Therefore, the generator 20 enters the power generation operation condition under the driving of the internal combustion engine 10, and the generator 20 is used to provide the power generation amount to the system. The internal combustion engine 10 can be, for example, a diesel engine, and the converter 50 is based on the rotation speed and power of the internal combustion engine 10. The parameter limits such as the load rate limit the power generation of the generator 20 to prevent overload protection of the internal combustion engine 10.

In this embodiment, according to the external speed control command, the converter 50 converts the voltage output from the generator 20 and controls the start-up operation of the motor 30. The operation of the motor 30 drives the system to be driven 40 to operate, and at the same time, the converter 50 generates power. The voltage outputted by the machine 20 is stepped down, and the voltage after the step-down process can be used to charge the battery 60. In the embodiment, the battery 60 is used to provide a voltage when the converter 50 drives the generator 20 to start. Specifically, The converter 50 raises the DC12V voltage of the battery 60 to DC120V, so that the intermediate DC bus voltage is DC120V, thereby driving the generator 20 to operate. When the generator 20 is running, the converter 50 controls the generator according to the starting requirement of the internal combustion engine 10. The output speed, torque and other parameters of 20 (generally the starting speed of the internal combustion engine 10 is 100-120 rpm, and the torque is 400-450 Nm), so that the internal combustion engine 10 is started.

In this embodiment, the electric drive system controls the generator 20 and the electric motor 30 through the converter 50. For power transmission, the converter 50 controls the amount of power generated by the generator 20 according to the actual energy consumption, so that the internal combustion engine 10 is maintained in an effective fuel operation, which can effectively save energy, and at the same time, the electric drive system is driven by the motor 30. Operation, the operator's control of the running speed of the device can be realized only by the pedal controlling the rotation speed of the motor 30, eliminating the clutch-shifting process in the conventional mechanical transmission system, the operation is simple, and the operator's requirement is lowered, and In the existing mechanical transmission system, the accelerator pedal is used to control the output of the internal combustion engine. If the gear position is low and the throttle is large, the engine speed is too high, resulting in waste of energy.

Moreover, the mechanical transmission components of the electric drive system are greatly reduced, and the operation of the equipment operation is not required by frequent operation of the mechanical components, thereby reducing mechanical wear and impact, and the reduction of mechanical components can also effectively reduce mechanical noise.

The control progress of the electric drive system provided by the embodiment mainly depends on the control of the rotational speed of the motor 30, and the control accuracy of the converter 50 for the motor 30 in the closed loop mode is 1‰, which greatly improves the overall control precision of the system. The main operating components of the electric drive system provided by the example are the generator 20 and the electric motor 30, and there is no wear between the two, and there is no need to replenish the grease under normal use (in the existing mechanical transmission system, the clutch, the shifting) The box or the like easily causes the contact surface to wear, requires long-term lubrication, periodically replaces the grease or the oil, so that the maintenance cost is high, and the generator 20 is directly connected to the internal combustion engine 10, and the motor 30 is directly connected to the system to be driven 40, and the entire external connection Simple and easy to check for repairs.

In this embodiment, the generator 20 can be a three-phase asynchronous generator, and the motor 30 can be a three-phase asynchronous motor, wherein a three-phase asynchronous generator and an electric motor are used, and the outer shape is small and the power density is large, thereby effectively saving equipment (such as a tractor). ) installation space.

Therefore, the electric drive system provided by the embodiment is connected to the internal combustion engine through a generator, the converter is connected to the generator, the battery and the motor, and the motor is connected to the system to be driven, so that the converter first boosts the voltage of the battery. The process is to drive the generator to start running, the operation of the generator drives the internal combustion engine to start running, and after the internal combustion engine starts running, the power output is sent to the generator, so that the generator generates electricity, and the converter converts the output voltage of the generator according to the external speed control command. The driving motor is operated, and the operation of the motor drives the system to be driven to operate. During operation, the control of the running speed of the device can be realized only by controlling the rotational speed of the motor, and the rotational speed of the motor is controlled by the pedal connected to the motor, so The frequent clutch-shifting process in the transmission mechanical transmission system is omitted in the transmission system. It is simpler, and there is no wear between the two main running parts of the generator and the motor, thereby reducing mechanical wear and impact and improving transmission efficiency. Therefore, the electric drive system provided by the invention solves the existing mechanical transmission process. The transmission device is subject to wear, complicated operation and high technical requirements for the operator.

2 is a schematic structural diagram of another embodiment of the electric drive system of the present invention. Based on the above embodiment, in the embodiment, the converter 50 includes: a first converter 501, a second converter 502 and a third change. The flow converter 503, wherein the first current transformer 501 is connected to the battery 60, the second current transformer 502 and the third current transformer 503, respectively, and the second current transformer 502 and the third current transformer 503 and the generator 20, respectively Connected, the third converter 503 is connected to the motor 30. When the external start command is sent to the converter 50, the first converter 501 starts to work, enters the boost mode, and the battery 60 is passed through the BOOST circuit. The DC12V voltage rises to DC120V, at which time the intermediate DC bus voltage is DC120V, then the second converter 502 starts running, and the DC bus energy is used to drive the generator 20 to run in the motor condition (that is, the generator 20 acts as the motor at this time) The internal combustion engine 10 is driven. According to the starting requirement of the internal combustion engine 10, the second converter 502 controls the output speed of the generator 20 to be 100-120 rpm and the torque is 400-450 Nm to drive the internal combustion engine 10 (such as a diesel engine) to start. After the internal combustion engine 10 is started, the second converter 502 controls the generator 20 to enter the power generation operation condition (that is, the generator 20 is used as a power generation device to generate power), and the DC bus voltage value DC840V is established, and the third converter 503 detects When the external speed control command is issued, according to the external speed control command, the third converter 503 takes power from the DC bus, drives the motor 30 to operate, and the operation of the motor 30 drives the system to be driven to operate. In this embodiment, when the system is started, the first converter 501 operates in a boost mode to assist in realizing power generation control of the generator 20; when the generator 20 starts generating power, the first converter 501 operates in a step-down manner. The mode can provide a DC 14V, 3kW DC control power supply, so that the battery 60 connected to the first converter 501 can be charged.

3 is a schematic view showing the connection structure of the converter in the electric drive system of the present invention. On the basis of the above embodiment, as shown in FIG. 3, in the present embodiment, the second converter 502 and the third converter 503 are both It is composed of two insulated gate bipolar transistors (IGBTs) in parallel. When the system is running, the generator 20 is driven by the internal combustion engine 10, and under the control of the second converter 502, the power generation operation is started, and the DC is established. The bus voltage value is DC840V, and the third converter 503 takes power from the DC bus and controls the motor 30 to operate. Further, this embodiment The first converter 501 is a DC-DC converter (such as the DC-DC converter in FIG. 3), and the DC-DC converter adopts a two-stage BUCK circuit. When the system is started, the DC-DC is changed. The current device operates in the boost mode, and raises the DC12V voltage of the external battery to DC120V. At this time, the intermediate DC bus voltage is DC120V, which can assist the power generation control of the generator 20; when the generator 20 starts generating electricity, the DC-DC converter The device operates in a buck mode, taking power from the DC bus voltage and reducing it to DC 14V to charge the external battery 60.

4 is a schematic view showing the connection between a current transformer and a generator in the electric drive system of the present invention, and FIG. 5 is a schematic view showing the connection between the current transformer and the electric motor in the electric drive system of the present invention, as shown in FIG. 4-5, the generator 20 and the first The two converters 502 are connected by a main cable 23, a speed sensor output signal line 22 and a temperature sensor output signal line 21. Specifically, the main circuit of the three main cables 23 of the generator 20 and the second converter 502 Connected, the two-way speed sensor output signal line 22 of the generator 20 is connected to the second converter 502 speed detecting circuit, and the five-way temperature sensor output signal line 21 of the generator 20 is connected to the second converter 502 temperature detecting circuit.

Correspondingly, the motor 30 and the third converter 503 are connected by the main cable 33, the speed sensor output signal line 32 and the temperature sensor output signal line 31. Specifically, the three main cables 33 and the third change of the motor 30 are connected. The main circuit of the streamer 503 is connected, and the two-way speed sensor output signal line 32 of the motor 30 is connected to the third converter 503 speed detecting circuit, and the temperature of the five-way temperature sensor output signal line 31 and the third converter 503 of the motor 30 Detecting a circuit connection, wherein the second converter 502 and the third converter 503 can be connected by a CAN bus, wherein the third converter 503 sends a power request command to the second converter 502 via the CAN bus. The second converter 502 controls the power generation of the generator 20 according to the required power. Meanwhile, the second converter 502 limits the power generation of the generator 20 according to parameter limits such as the rotational speed, power, and load rate of the internal combustion engine 1. To prevent overload protection of the internal combustion engine 110.

Further, FIG. 6 is a schematic flow chart of a control method of an electric drive system according to the present invention. The electric drive system can refer to the electric drive system according to any of the above embodiments. As shown in FIG. 6, the method includes the following steps:

Step 601: The converter drives the generator to start according to the start command to drive the internal combustion engine to start.

In this embodiment, referring to the structure of FIG. 1, after the converter 50 receives the start command, the converter 12 starts the operation and raises the DC12V voltage of the battery 60 to DC120V, so that the middle is straight. The bus voltage is DC 120V, thereby driving the generator 20 to operate. When the generator 20 is running, according to the starting requirement of the internal combustion engine 10, the converter 50 controls the output speed, torque and other parameters of the generator 20 (generally starting the internal combustion engine 10) The rotational speed is 100-120 rpm and the torque is 400-450 Nm, which drives the internal combustion engine 10 to start.

Step 602: After the internal combustion engine starts running, the generator generates power by the internal combustion engine and outputs alternating current;

In this embodiment, after the internal combustion engine 10 is started, the internal combustion engine 10 outputs power to the generator 20, and the converter 502 controls the generator 20 to enter the power generation operating condition and outputs alternating current (specifically, three-phase AC 600V), and the converter 502 is The output AC power establishes the DC bus voltage value DC840V, that is, the AC power is converted into DC power.

Step 603: The converter converts the alternating current output by the generator into direct current according to a speed control instruction to drive the motor to start running.

In this embodiment, when the converter detects the speed control command, the converter 50 takes power from the DC bus according to the external speed control command, and the drive motor 30 operates, and the operation of the motor 30 drives the system to be driven 40 to operate.

The control method of the electric drive system provided by the embodiment realizes accurate control of the electric drive system and improves the transmission efficiency of the electric drive system.

Further, FIG. 7 is still another schematic flowchart of the control method of the electric drive system of the present invention, wherein the structure of the electric drive system refers to FIG. 2, and the converter 50 includes: a first converter 501, a second converter 502, and The third converter 503 has a control method specifically as follows:

Step 701: The control power is turned on.

Step 702, the system self-test;

After the control power is turned on, the control circuit boards of the first converter 501, the second converter 502, and the third converter 503 are started, and the system enters a self-test state. If an abnormality occurs, an alarm is issued. If the self-test is normal, the startup operation will be started according to the instruction.

Step 703: The first converter enters a boosting working mode according to the startup command, and establishes a DC bus voltage of DC12V.

In this embodiment, after the converter detects the start command, the first converter 501 enters the boosting mode, and the DC12V voltage of the external battery 60 is raised to DC 120V through the BOOST circuit, and the intermediate DC bus voltage is DC 120V.

Step 704: The second converter starts electric operation control.

In this embodiment, the second converter 502 is started to operate, and the DC bus voltage is used to drive the generator 20 to operate in a motor operating condition. That is, the generator 20 is not used for non-power generation, but the internal combustion engine 10 is driven as an electric motor. Starting, the second converter 501 controls the output speed and torque of the generator 20 according to the starting requirement of the internal combustion engine 10, so that the internal combustion engine 10 (for example, a diesel engine) is started, and after the internal combustion engine 10 is started, the power is output to the generator 20, and the generator 20 generates electric power according to the power of the internal combustion engine 10.

Step 705: The second converter performs power generation operation control;

In the present embodiment, in order to control the power generation of the generator 20, the second converter 502 limits the power generation of the generator 20 according to the parameter limits such as the rotational speed, power, and load rate of the internal combustion engine 10, and prevents the internal combustion engine 10 from being The overload protection, and the second converter 502 controls the power generation of the generator 20 according to the power request fed back by the third converter 503.

Step 706: The third converter starts the operation according to the speed control instruction.

In this embodiment, when the third converter 503 detects the external speed control command, the operation is started according to the speed control command. Specifically, the third converter 503 is from the DC bus (at this time, the DC is established through the second converter). The bus voltage value is DC 840V), and the motor 30 is driven to operate.

Step 707, the motor runs;

In this embodiment, after the motor 30 is operated, the system to be driven 40 is driven to operate. In this embodiment, when the running speed of the device needs to be controlled, only the speed of the motor 30 can be controlled by the pedal, and at the same time, the motor When the rotational speed of 30 changes, the power request is fed back to the second converter 502 through the third converter 503, and the second converter 502 controls the power generated by the generator 20 in accordance with the power request.

In this embodiment, the alternating current outputted by the generator 20 is converted into direct current by the second converter 502, and the DC bus voltage is set to DC840V, wherein the third converter 503 takes power from the DC bus (DC840V) according to the speed control command. To drive the motor 30 to operate, the first converter 501 takes power from the DC bus and performs step 708.

Step 708, the first converter enters a buck mode;

In this embodiment, the first converter 501 receives power from the DC bus voltage through the BUCK circuit and reduces it to DC 14V to charge the external battery 60.

Step 709, charging the battery.

In the present embodiment, the battery 60 is used to supply the converter 50 with a voltage when the system is started to cause the converter 50 to start. During the operation of the system, the converter 50 supplies a certain voltage to the battery 60, so that the battery 60 Charge it.

Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that The technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; and the modifications or substitutions do not deviate from the technical solutions of the embodiments of the present invention. range.

Claims

An electric drive system, comprising:

a generator connected to the internal combustion engine, a converter connected to the battery, and an electric motor connected to the system to be driven, wherein the converter is respectively connected to the generator and the motor;

The converter is configured to drive the generator and the generator to operate, the generator is configured to drive the internal combustion engine to start under the driving of the converter, so that the internal combustion engine starts to generate electricity The machine transmits power, and the engine is used to drive the to-be-driven system to start operation under the driving of the converter.
The electric drive system according to claim 1, wherein said current transformer comprises: a first current transformer, a second current transformer and a third current transformer, wherein said first current transformer The battery is connected, the second converter is connected to the first converter, the third converter and the generator, respectively, the third converter and the first converter The device is coupled to the motor.
The electric drive system of claim 2 wherein said first converter is a direct current DC-DC converter.
The electric drive system according to claim 2 or 3, wherein the second current transformer and the third current transformer are each composed of two insulated gate bipolar transistor IGBTs connected in parallel.
The electric drive system according to claim 2, wherein a main cable and a signal are passed between said generator and said second converter and between said electric motor and said third converter The cables are connected, wherein the signal cable includes a speed sensor output signal line and a temperature sensor output signal line.
An electric drive system according to any of claims 1-3, wherein said generator is a three-phase asynchronous generator and said electric motor is a three-phase asynchronous motor.
A control method of an electric drive system, characterized in that the electric drive system is the electric drive system according to any one of claims 1-6, and the control method of the electric drive system comprises:

The converter drives the generator to start according to the start command to drive the internal combustion engine to start;

After the internal combustion engine is started, the generator generates electricity and outputs alternating current under the driving of the internal combustion engine;

The converter converts the alternating current output by the generator into a straight according to a speed control command The galvanic current starts the operation by driving the motor.
The method of claim 7, further comprising: said converter converting the alternating current output by said generator and stepping down for charging the battery.
The method of claim 7, further comprising: said converter controlling a power generation of said generator in accordance with a power request command.