Motor driving method and circuit based on energy feedback elimination of electric large engineering vehicle

Abstract

The present invention relates to the field of power electronics technology, and discloses a motor driving method and circuit based on the elimination of energy feedback of electric large engineering vehicles, including when the actual motor speed of a three-phase motor needs to be reduced and the three-phase motor generates energy feedback, within a preset time period, the MOS tube in the upper bridge arm in the power conversion unit of the electric large engineering vehicle driving circuit is controlled to work in a cutoff region, and the MOS tube in the lower bridge arm is controlled to work in a linear region, so that the energy feedback generated by the three-phase motor is consumed by the MOS tube in the lower bridge arm before reaching the battery, and is clamped within a safe voltage range by the body diode of the MOS tube in the upper bridge arm; after the preset time period ends, the MOS tubes in the upper bridge arm and the lower bridge arm are operated in a saturation region, and the size of the three-phase alternating current output by the power conversion unit is reduced by reducing the duty cycle of the MOS tube working in the saturation region. The present invention eliminates energy feedback by controlling the working state of the MOS tube, and does not require additional power components.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a motor driving method and circuit based on energy feedback elimination of electric large engineering vehicles. Background Art

[0002] Compared with fuel-powered large engineering vehicles, electric large engineering vehicles can save more than 45% of energy. At the same time, electric drive is pollution-free and more environmentally friendly. Common electric large engineering vehicles include forklifts, aerial work platforms and excavators, all of which have the characteristics of strong load-carrying capacity, complex working conditions and energy saving. At present, 10-ton electric forklifts and 40-meter aerial work platforms have been applied to the market, and most engineering vehicles work in the wild, with rugged mountain roads, large temperature changes in the working environment, and heavy loads. As a result, during braking or deceleration, electric large engineering vehicles have large inertia and are prone to energy feedback, which damages the equipment in the electric large engineering vehicles and reduces the service life of the vehicles.

[0003] Reference Figure 1 As shown in the figure, it is a schematic diagram of the traditional electric large engineering vehicle drive circuit; power devices M1, M2, M3, M4, M5, M6, D1, D2, D3, D4, D5, D6 form a power conversion unit, and the motor can be simplified as a three-phase inductor; during normal operation, the three-phase inductors L1, L2, and L3 all have current flowing into and out of the motor, and the sum of the three currents on the three-phase inductor is 0; assuming that the direction of the L1 current is to flow out of the motor, due to the characteristics of the inductor, the 2nd foot of L1 is positive. Under special working conditions, the circuit breaker is cut off, and the power conversion unit has no energy input. The current flowing through the inductor L1 changes dramatically, and the 1st foot of L1 becomes positive, that is, point C in the figure becomes a high voltage. Large engineering machinery vehicles have a large load and a large inertia. The voltage at point C will be very high. It will be added to B+ through the diode D3, and a very high voltage difference will be generated between B+ and B-. This voltage will be added to both ends of the power device in the power conversion unit, exceeding the rated voltage of the power device, and it is very easy to break down the device. This process is called energy regeneration for electric large construction vehicles. If not handled properly, it can cause serious damage to the equipment.

[0004] At present, in order to solve the energy feedback problem of electric large engineering vehicles, usually Figure 1 In the conventional working circuit of the electric large engineering vehicle shown in FIG. 1 , a discharge path is added; Figure 2 As shown in the figure, it is a schematic diagram of the improved drive circuit of the electric large engineering vehicle; by adding a discharge path, that is, adding the power device MOS M7 and the power resistor R1, when a special working condition occurs, the control system samples that the voltage at both ends of B+ and B- is too high, controls MOS M7 to close and conduct, and the voltage at both ends of B+ and B- is added to the power resistor R1, so as to realize the discharge of B+ and B-, and play a protective role; but the method of adding the discharge path increases the cost of the control circuit, and due to the large volume of the power resistor R1, the volume of the control circuit becomes larger.

[0005] In summary, the existing method for eliminating energy feedback of electric large engineering vehicles requires the addition of a discharge path, which increases the cost and volume of the control circuit, and further increases the production cost of the electric large engineering vehicle and limits the layout of the internal equipment of the vehicle when eliminating the energy feedback of the electric large engineering vehicle. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problem of increased cost and volume of the control circuit caused by eliminating energy feedback by adding a discharge path in the prior art.

[0007] In order to solve the above technical problems, the present invention provides a motor driving method based on energy feedback elimination of electric large engineering vehicles, comprising:

[0008] When the actual motor speed of the three-phase motor needs to be reduced and the three-phase motor generates energy feedback, within a preset time period, the MOS tube in the upper bridge arm in the power conversion unit in the electric large engineering vehicle drive circuit is controlled to work in the cutoff region, and the MOS tube in the lower bridge arm is controlled to work in the linear region, so that the energy feedback generated by the three-phase motor is consumed by the MOS tube in the lower bridge arm before reaching the battery, and then clamped within the safe voltage range by the body diode of the MOS tube in the upper bridge arm; after the preset time period ends, the MOS tubes in the upper bridge arm and the lower bridge arm are operated in the saturation region, and the size of the three-phase alternating current output by the power conversion unit is reduced by reducing the duty cycle of the MOS tube working in the saturation region;

[0009] When the actual motor speed of the three-phase motor needs to be increased, the MOS tubes in the upper bridge arm and the lower bridge arm are made to work in the saturation region. By increasing the duty cycle of the MOS tube working in the saturation region, the size of the three-phase alternating current output by the power conversion unit is increased.

[0010] Preferably, the MOS tube is an N-channel MOS tube, and the working state of the MOS tube is controlled by controlling the voltage input to the gate of the MOS tube, including:

[0011] Control the gate voltage of the MOS tube to be no greater than 0.5V, so that the MOS tube works in the cut-off region;

[0012] The gate voltage of the MOS tube is controlled to be in the range of [2V, 4V], so that the MOS tube works in the linear region;

[0013] The gate voltage of the MOS tube is controlled to be greater than 10V, so that the MOS tube works in the saturation region.

[0014] Preferably, the situations where the actual motor speed of the three-phase motor needs to be reduced include: emergency braking and deceleration of electric large engineering vehicles;

[0015] When a heavy-load engineering vehicle brakes urgently, the actual motor speed of the three-phase motor needs to be 0;

[0016] When the heavy-load engineering vehicle decelerates, the actual motor speed of the three-phase motor needs to be reduced to a first preset speed, which is greater than or equal to 0 and less than or equal to the actual motor speed of the three-phase motor.

[0017] Preferably, when the actual motor speed of the three-phase motor needs to be reduced to a first preset speed, the method includes:

[0018] In a preset time period, the MOS tube in the upper bridge arm is controlled to work in the cut-off region, and the MOS tube in the lower bridge arm is controlled to work in the linear region. At this time, the MOS tube in the lower bridge arm exhibits resistance characteristics, and after the energy feedback is consumed, the body diode of the MOS tube in the upper bridge arm is clamped within the safe voltage range;

[0019] After the preset time period ends, the MOS tubes in the upper bridge arm and the lower bridge arm are both operated in the saturation region. By reducing the duty cycle of the MOS tubes operating in the saturation region, the size of the three-phase alternating current output by the power conversion unit is reduced and input into the three-phase motor until the actual motor speed of the three-phase motor is reduced to the first preset speed.

[0020] Preferably, when the actual motor speed of the three-phase motor is required to be 0, the method includes:

[0021] In a preset time period, the MOS tube in the upper bridge arm is controlled to work in the cut-off region, and the MOS tube in the lower bridge arm is controlled to work in the linear region. At this time, the MOS tube in the upper bridge arm exhibits resistance characteristics, and after the energy feedback is consumed, the body diode of the MOS tube in the upper bridge arm is clamped within the safe voltage range;

[0022] After the preset time period ends, the MOS tubes in the upper bridge arm and the lower bridge arm are both operated in the cut-off region, so that the magnitude of the three-phase alternating current output by the power conversion unit is zero.

[0023] Preferably, the situation where the actual motor speed of the three-phase motor needs to be increased includes the starting and acceleration of a large electric construction vehicle.

[0024] Preferably, when the actual motor speed of the three-phase motor needs to be increased, the method includes:

[0025] The MOS tubes in the upper bridge arm and the lower bridge arm are made to work in the saturation region, and the duty cycle of the MOS tube working in the saturation region is increased, so that the current of the three-phase alternating current output by the power conversion unit is increased and then input to the three-phase motor, thereby driving the actual motor speed of the three-phase motor to increase.

[0026] This embodiment provides an energy feedback elimination circuit for an electric large engineering vehicle, comprising:

[0027] The electric large engineering vehicle drive circuit comprises:

[0028] Batteries;

[0029] The power conversion unit is connected in parallel at both ends of the battery, including an upper bridge arm and a lower bridge arm, and converts the DC power output by the battery into three-phase AC power, and outputs it to the three-phase motor through the three-phase output terminal;

[0030] The control unit is communicatively connected with the power conversion unit, and utilizes the motor driving method based on the elimination of energy feedback of electric large engineering vehicles as described above, and adjusts the size of the three-phase alternating current input to the three-phase motor by controlling the working states of multiple MOS tubes in the power conversion unit, and eliminates the energy feedback generated by the three-phase motor.

[0031] Preferably, the power conversion unit comprises an upper bridge arm and a lower bridge arm;

[0032] The upper bridge arm comprises:

[0033] A first MOS tube, a drain of which is connected to the positive electrode of the battery, and a gate of which is connected to the control unit;

[0034] a first body diode connected in parallel to both ends of the first MOS tube, with an anode connected to the source of the first MOS tube and a cathode connected to the drain of the first MOS tube;

[0035] A second MOS tube, a drain of which is connected to the positive electrode of the battery, and a gate of which is connected to the control unit;

[0036] a second body diode connected in parallel to both ends of the second MOS tube, with an anode connected to the source of the second MOS tube and a cathode connected to the drain of the second MOS tube;

[0037] A third MOS tube, a drain of which is connected to the positive electrode of the battery, and a gate of which is connected to the control unit;

[0038] A third body diode is connected in parallel to both ends of the third MOS tube, an anode of the third body diode is connected to the source of the third MOS tube, and a cathode of the third body diode is connected to the drain of the third MOS tube;

[0039] The lower bridge arm comprises:

[0040] a fourth MOS tube, whose drain is connected to the source of the first MOS tube, whose source is connected to the negative electrode of the battery, and whose gate is connected to the control unit;

[0041] a fourth body diode, connected in parallel to both ends of the fourth MOS tube, with an anode connected to the source of the fourth MOS tube and a cathode connected to the drain of the fourth MOS tube;

[0042] a fifth MOS tube, whose drain is connected to the source of the second MOS tube, whose source is connected to the negative electrode of the battery, and whose gate is connected to the control unit;

[0043] a fifth body diode, connected in parallel to both ends of the fifth MOS tube, with an anode connected to the source of the fifth MOS tube and a cathode connected to the drain of the fifth MOS tube;

[0044] a sixth MOS tube, whose drain is connected to the source of the third MOS tube, whose source is connected to the negative electrode of the battery, and whose gate is connected to the control unit;

[0045] A sixth body diode is connected in parallel to both ends of the sixth MOS tube, an anode of the sixth body diode is connected to the source of the sixth MOS tube, and a cathode of the sixth body diode is connected to the drain of the sixth MOS tube.

[0046] Preferably, it also includes a circuit breaker, one end of which is connected to the positive electrode of the battery, and the other end of which is connected to the drains of the first MOS tube, the second MOS tube and the third MOS tube.

[0047] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0048] The motor driving method and circuit based on the elimination of energy feedback of electric large engineering vehicles described in the present invention, when the electric large engineering vehicle decelerates to generate energy feedback, the MOS tube of the upper bridge arm in the power conversion unit is controlled to be in the cut-off zone and the MOS tube of the lower bridge arm is in the linear zone within a preset time period to eliminate energy feedback; the present invention extends the retention time of the linear zone so that the MOS tube in the lower bridge arm exhibits resistance characteristics. At this time, the voltage difference generated by the energy feedback at the three-phase output end will be added to the MOS tube of the lower bridge arm and consumed, and then reach the two ends of the battery after being clamped within the safe voltage range through the body diode of the upper bridge arm, so that the positive and negative ends of the battery will not generate a high voltage difference, avoiding the damage of the power device by the energy feedback, and protecting the power device in the circuit; after the energy feedback is eliminated, the duty cycle of the MOS tube is used to adjust the size of the three-phase alternating current output by the power conversion unit. In addition, the present invention does not require additional electronic components, saves costs, reduces the volume of the control circuit, and provides abundant available space for the layout of internal equipment of electric large engineering vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0050] Figure 1 It is a schematic diagram of the traditional electric large engineering vehicle drive circuit;

[0051] Figure 2It is a schematic diagram of the improved drive circuit of an electric large engineering vehicle;

[0052] Figure 3 is a flow chart of steps of a motor driving method based on energy feedback elimination of an electric large construction vehicle;

[0053] Figure 4 It is an equivalent schematic diagram of the driving circuit when the upper bridge arm MOS tube works in the cut-off region;

[0054] Figure 5 It is an equivalent schematic diagram of a driving circuit in which the upper bridge arm MOS tube works in the cutoff region and the lower bridge arm MOS tube works in the linear region. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0056] Reference Figure 3 As shown, the step flow chart of the motor driving method based on the elimination of energy feedback of electric large engineering vehicles of the present invention is applied to the driving circuit of electric large engineering vehicles, specifically including:

[0057] When the actual motor speed of the three-phase motor needs to be reduced and the three-phase motor generates energy feedback, within a preset time period, the MOS tube in the upper bridge arm in the power conversion unit in the electric large engineering vehicle drive circuit is controlled to work in the cutoff region, and the MOS tube in the lower bridge arm is controlled to work in the linear region, so that the energy feedback generated by the three-phase motor is consumed by the MOS tube in the lower bridge arm before reaching the battery, and then clamped within the safe voltage range by the body diode of the MOS tube in the upper bridge arm; after the preset time period ends, the MOS tubes in the upper bridge arm and the lower bridge arm are operated in the saturation region, and the size of the three-phase alternating current output by the power conversion unit is reduced by reducing the duty cycle of the MOS tube working in the saturation region;

[0058] When the actual motor speed of the three-phase motor needs to be increased, the MOS tubes in the upper bridge arm and the lower bridge arm are made to work in the saturation region. By increasing the duty cycle of the MOS tube working in the saturation region, the size of the three-phase alternating current output by the power conversion unit is increased.

[0059] Specifically, in the embodiment of the present invention, the MOS tube is an N-channel MOS tube, and the working state of the MOS tube is controlled by controlling the voltage input to the gate of the MOS tube, including:

[0060] Control the gate voltage of the MOS tube to be no greater than 0.5V, so that the MOS tube works in the cut-off region;

[0061] The gate voltage of the MOS tube is controlled to be in the range of [2V, 4V], so that the MOS tube works in the linear region;

[0062] The gate voltage of the MOS tube is controlled to be greater than 10V, so that the MOS tube works in the saturation region.

[0063] In the embodiment of the present invention, situations where the actual motor speed of the three-phase motor needs to be reduced include: emergency braking and deceleration of a large electric engineering vehicle.

[0064] When a heavy-load engineering vehicle performs emergency braking, the actual motor speed of the three-phase motor needs to be 0; specifically, within a preset time period, the MOS tube in the upper bridge arm is controlled to work in the cut-off region, and the MOS tube in the lower bridge arm is controlled to work in the linear region. At this time: the MOS tube in the upper bridge arm exhibits a resistance characteristic, and after the energy feedback is consumed, the body diode of the MOS tube in the upper bridge arm is clamped within a safe voltage range; after the preset time period ends, the MOS tubes in the upper bridge arm and the lower bridge arm are both operated in the cut-off region, so that the magnitude of the three-phase alternating current output by the power conversion unit is 0.

[0065] When a heavy-load engineering vehicle decelerates, it is necessary to reduce the actual motor speed of the three-phase motor to a first preset speed, wherein the first preset speed is greater than or equal to 0 and less than or equal to the actual motor speed of the three-phase motor; specifically, within a preset time period, the MOS tube in the upper bridge arm is controlled to operate in a cutoff region, and the MOS tube in the lower bridge arm is controlled to operate in a linear region, at which time: the MOS tube in the lower bridge arm exhibits a resistance characteristic, and after consuming the energy feedback, the body diode of the MOS tube in the upper bridge arm is clamped within a safe voltage range; after the preset time period ends, the MOS tubes in both the upper bridge arm and the lower bridge arm are made to operate in a saturation region, and by reducing the duty cycle of the MOS tube operating in the saturation region, the size of the three-phase alternating current output by the power conversion unit is reduced, and the three-phase motor is input until the actual motor speed of the three-phase motor is reduced to the first preset speed.

[0066] Specifically, in the embodiment of the present invention, the length of the preset time period is controlled based on the amount of feedback energy, and the preset time period is usually set to 1 ms.

[0067] In the embodiment of the present invention, the situation where the actual motor speed of the three-phase motor needs to be increased includes the start-up and acceleration of electric large engineering vehicles. Specifically, the MOS tubes in the upper bridge arm and the lower bridge arm are both operated in the saturation region, and the duty cycle of the MOS tubes operating in the saturation region is increased, so that the current of the three-phase alternating current output by the power conversion unit is increased and then input to the three-phase motor, driving the actual motor speed of the three-phase motor to increase.

[0068] The motor driving method based on the elimination of energy feedback of electric large engineering vehicles described in the present invention eliminates energy feedback by controlling the MOS tube of the upper bridge arm in the power conversion unit to be in the cut-off region and the MOS tube of the lower bridge arm to be in the linear region within a preset time period when the electric large engineering vehicle decelerates to generate energy feedback; the present invention extends the retention time of the linear region so that the MOS tube in the lower bridge arm exhibits a resistance characteristic. At this time, the voltage difference generated by the energy feedback at the three-phase output end is added to the MOS tube of the lower bridge arm and consumed, and then reaches the two ends of the battery after being clamped within the safe voltage range through the body diode of the upper bridge arm, so that a high voltage difference is not generated at the positive and negative ends of the battery, thereby avoiding damage to the power device by energy feedback and protecting the power device in the circuit; after the energy feedback is eliminated, the duty cycle of the MOS tube is used to adjust the size of the three-phase alternating current output by the power conversion unit.

[0069] Based on the above embodiments, the embodiments of the present invention further provide a motor drive circuit based on energy feedback elimination of electric large engineering vehicles, comprising:

[0070] The electric large engineering vehicle drive circuit comprises:

[0071] Batteries;

[0072] The power conversion unit is connected in parallel at both ends of the battery, including an upper bridge arm and a lower bridge arm, and converts the DC power output by the battery into three-phase AC power, and outputs it to the three-phase motor through the three-phase output terminal;

[0073] The control unit is communicatively connected with the power conversion unit, and utilizes the motor driving method based on the elimination of energy feedback of electric large engineering vehicles as described above, and adjusts the size of the three-phase alternating current input to the three-phase motor by controlling the working states of multiple MOS tubes in the power conversion unit, and eliminates the energy feedback generated by the three-phase motor.

[0074] Specifically, the power conversion unit includes an upper bridge arm and a lower bridge arm;

[0075] The upper bridge arm comprises:

[0076] A first MOS tube, a drain of which is connected to the positive electrode of the battery, and a gate of which is connected to the control unit;

[0077] a first body diode connected in parallel to both ends of the first MOS tube, with an anode connected to the source of the first MOS tube and a cathode connected to the drain of the first MOS tube;

[0078] A second MOS tube, a drain of which is connected to the positive electrode of the battery, and a gate of which is connected to the control unit;

[0079] a second body diode connected in parallel to both ends of the second MOS tube, with an anode connected to the source of the second MOS tube and a cathode connected to the drain of the second MOS tube;

[0080] A third MOS tube, a drain of which is connected to the positive electrode of the battery, and a gate of which is connected to the control unit;

[0081] A third body diode is connected in parallel to both ends of the third MOS tube, an anode of the third body diode is connected to the source of the third MOS tube, and a cathode of the third body diode is connected to the drain of the third MOS tube;

[0082] The lower bridge arm comprises:

[0083] a fourth MOS tube, whose drain is connected to the source of the first MOS tube, whose source is connected to the negative electrode of the battery, and whose gate is connected to the control unit;

[0084] a fourth body diode, connected in parallel to both ends of the fourth MOS tube, with an anode connected to the source of the fourth MOS tube and a cathode connected to the drain of the fourth MOS tube;

[0085] a fifth MOS tube, whose drain is connected to the source of the second MOS tube, whose source is connected to the negative electrode of the battery, and whose gate is connected to the control unit;

[0086] a fifth body diode, connected in parallel to both ends of the fifth MOS tube, with an anode connected to the source of the fifth MOS tube and a cathode connected to the drain of the fifth MOS tube;

[0087] a sixth MOS tube, whose drain is connected to the source of the third MOS tube, whose source is connected to the negative electrode of the battery, and whose gate is connected to the control unit;

[0088] A sixth body diode is connected in parallel to both ends of the sixth MOS tube, an anode of the sixth body diode is connected to the source of the sixth MOS tube, and a cathode of the sixth body diode is connected to the drain of the sixth MOS tube.

[0089] Specifically, the embodiment of the present invention further includes a circuit breaker, one end of which is connected to the positive electrode of the battery, and the other end of which is connected to the drains of the first MOS tube, the second MOS tube and the third MOS tube.

[0090] Reference Figure 4 As shown, it is an equivalent schematic diagram of the driving circuit of the upper bridge arm MOS tube working in the cut-off region; based on Figure 1 In the circuit shown, under special working conditions, the circuit breaker is disconnected, and the control unit samples that the voltage at both ends of the battery B+ and B- is too high. The control unit controls M1, M2, M3 and M7 to disconnect, M1, M2, M3 and M7 are equivalent to open circuit, and M4, M5, M6 are closed. By controlling the voltage amplitude of M4, M5, M6, M4, M5, M6 work in the linear region and play the role of discharge resistors. At this time, its equivalent circuit is as follows Figure 4 As shown;

[0091] Reference Figure 5 As shown in FIG. 1 , it is an equivalent schematic diagram of a driving circuit in which the upper bridge arm MOS tube works in the cut-off region and the lower bridge arm MOS tube works in the linear region. Specifically, based on Figure 4 In the circuit shown, power devices M4, M5, and M6 work in the linear region respectively, which are similar to resistors and consume current. The differential pressure generated by A, B, and C will be added to R4, R5, and R6. At this time, R4, R5, and R6 discharge, and diodes D1, D2, and D3 clamp. High voltage will not be generated at both ends of B+ and B-, which plays a role in protecting the power devices. Compared with the traditional discharge circuit, no additional components are used, which saves costs and reduces volume.

[0092] The motor driving method and circuit based on the elimination of energy feedback of electric large engineering vehicles described in the present invention, when the electric large engineering vehicle decelerates to generate energy feedback, the MOS tube of the upper bridge arm in the power conversion unit is controlled to be in the cut-off zone and the MOS tube of the lower bridge arm is in the linear zone within a preset time period to eliminate energy feedback; the present invention extends the retention time of the linear zone so that the MOS tube in the lower bridge arm exhibits resistance characteristics. At this time, the voltage difference generated by the energy feedback at the three-phase output end will be added to the MOS tube of the lower bridge arm and consumed, and then reach the two ends of the battery after being clamped within the safe voltage range through the body diode of the upper bridge arm, so that the positive and negative ends of the battery will not generate a high voltage difference, avoiding the damage of the power device by the energy feedback, and protecting the power device in the circuit; after the energy feedback is eliminated, the duty cycle of the MOS tube is used to adjust the size of the three-phase alternating current output by the power conversion unit. In addition, the present invention does not require additional electronic components, saves costs, reduces the volume of the control circuit, and provides abundant available space for the layout of internal equipment of electric large engineering vehicles.

[0093] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0094] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0095] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0097] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A motor driving method based on energy feedback elimination of electric large engineering vehicles, characterized in that: Applied to the drive circuit of electric large engineering vehicles, including: When the actual motor speed of the three-phase motor needs to be reduced and the three-phase motor generates energy feedback, within a preset time period, the MOS tube in the upper bridge arm of the power conversion unit in the electric large engineering vehicle drive circuit is controlled to work in the cutoff region, and the MOS tube in the lower bridge arm is controlled to work in the linear region, so that the energy feedback generated by the three-phase motor is consumed by the MOS tube in the lower bridge arm before reaching the battery, and then clamped within the safe voltage range by the body diode of the MOS tube in the upper bridge arm; after the preset time period ends, it includes: When the heavy-load engineering vehicle decelerates, it is necessary to reduce the actual motor speed of the three-phase motor to a first preset speed, wherein the first preset speed is greater than or equal to 0 and less than or equal to the actual motor speed of the three-phase motor; at this time, the MOS tubes in the upper bridge arm and the lower bridge arm are both operated in the saturation region, and the duty cycle of the MOS tubes operating in the saturation region is reduced, thereby reducing the size of the three-phase alternating current output by the power conversion unit and inputting the three-phase motor until the actual motor speed of the three-phase motor is reduced to the first preset speed; When a heavy-load engineering vehicle brakes urgently, the actual motor speed of the three-phase motor needs to be 0; at this time, the MOS tubes in the upper bridge arm and the lower bridge arm are both operated in the cut-off region, and the magnitude of the three-phase AC output by the power conversion unit is 0; When the actual motor speed of the three-phase motor needs to be increased, the MOS tubes in the upper bridge arm and the lower bridge arm are made to work in the saturation region. By increasing the duty cycle of the MOS tube working in the saturation region, the size of the three-phase alternating current output by the power conversion unit is increased.

2. The motor driving method based on eliminating energy feedback of electric large engineering vehicles according to claim 1 is characterized in that: The MOS tube is an N-channel MOS tube. The working state of the MOS tube is controlled by controlling the voltage input to the gate of the MOS tube, including: Control the gate voltage of the MOS tube to be no greater than 0.5V, so that the MOS tube works in the cut-off region; The gate voltage of the MOS tube is controlled to be in the range of [2V, 4V], so that the MOS tube works in the linear region; The gate voltage of the MOS tube is controlled to be greater than 10V, so that the MOS tube works in the saturation region.

3. The motor driving method based on eliminating energy feedback of electric large engineering vehicles according to claim 1 is characterized in that: Situations where the actual motor speed of a three-phase motor needs to be increased include starting and accelerating large electric construction vehicles.

4. The motor driving method based on eliminating energy feedback of electric large engineering vehicles according to claim 3 is characterized in that: When the actual motor speed of a three-phase motor needs to be increased, it includes: The MOS tubes in the upper bridge arm and the lower bridge arm are made to work in the saturation region, and the duty cycle of the MOS tube working in the saturation region is increased, so that the current of the three-phase alternating current output by the power conversion unit is increased and then input to the three-phase motor, thereby driving the actual motor speed of the three-phase motor to increase.

5. A motor drive circuit based on energy feedback elimination of electric large engineering vehicles, characterized in that: include: The electric large engineering vehicle drive circuit comprises: Batteries; The power conversion unit is connected in parallel at both ends of the battery, including an upper bridge arm and a lower bridge arm, and converts the DC power output by the battery into three-phase AC power, and outputs it to the three-phase motor through the three-phase output terminal; A control unit is communicatively connected to the power conversion unit, and utilizes the motor driving method based on the elimination of energy feedback of electric large engineering vehicles as described in any one of claims 1 to 4, and adjusts the size of the three-phase alternating current input to the three-phase motor by controlling the working states of multiple MOS tubes in the power conversion unit, and eliminates the energy feedback generated by the three-phase motor.

6. The motor drive circuit based on energy feedback elimination of electric large engineering vehicles according to claim 5 is characterized in that: The power conversion unit comprises an upper bridge arm and a lower bridge arm; The upper bridge arm comprises: A first MOS tube, a drain of which is connected to the positive electrode of the battery, and a gate of which is connected to the control unit; a first body diode connected in parallel to both ends of the first MOS tube, with an anode connected to the source of the first MOS tube and a cathode connected to the drain of the first MOS tube; A second MOS tube, a drain of which is connected to the positive electrode of the battery, and a gate of which is connected to the control unit; a second body diode connected in parallel to both ends of the second MOS tube, with an anode connected to the source of the second MOS tube and a cathode connected to the drain of the second MOS tube; A third MOS tube, a drain of which is connected to the positive electrode of the battery, and a gate of which is connected to the control unit; A third body diode is connected in parallel to both ends of the third MOS tube, an anode of the third body diode is connected to the source of the third MOS tube, and a cathode of the third body diode is connected to the drain of the third MOS tube; The lower bridge arm comprises: a fourth MOS tube, whose drain is connected to the source of the first MOS tube, whose source is connected to the negative electrode of the battery, and whose gate is connected to the control unit; a fourth body diode, connected in parallel to both ends of the fourth MOS tube, with an anode connected to the source of the fourth MOS tube and a cathode connected to the drain of the fourth MOS tube; a fifth MOS tube, whose drain is connected to the source of the second MOS tube, whose source is connected to the negative electrode of the battery, and whose gate is connected to the control unit; a fifth body diode, connected in parallel to both ends of the fifth MOS tube, with an anode connected to the source of the fifth MOS tube and a cathode connected to the drain of the fifth MOS tube; a sixth MOS tube, whose drain is connected to the source of the third MOS tube, whose source is connected to the negative electrode of the battery, and whose gate is connected to the control unit; A sixth body diode is connected in parallel to both ends of the sixth MOS tube, an anode of the sixth body diode is connected to the source of the sixth MOS tube, and a cathode of the sixth body diode is connected to the drain of the sixth MOS tube.

7. The motor drive circuit based on energy feedback elimination of electric large engineering vehicles according to claim 6 is characterized in that: It also includes a circuit breaker, one end of which is connected to the positive electrode of the battery, and the other end of which is connected to the drains of the first MOS tube, the second MOS tube and the third MOS tube.

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