WO2020043091A1

WO2020043091A1 - Protection method and system for inverter, and vehicle

Info

Publication number: WO2020043091A1
Application number: PCT/CN2019/102825
Authority: WO
Inventors: 徐鲁辉; 肖恺; 杜智勇
Original assignee: 比亚迪股份有限公司
Priority date: 2018-08-30
Filing date: 2019-08-27
Publication date: 2020-03-05
Also published as: BR112021003304A2; CN110875709B; CN110875709A

Abstract

Provided are a protection method and system for an inverter, and a vehicle. The inverter is used for driving an electric motor. The method comprises the following steps: acquiring a rotation speed of an electric motor; when the rotation speed of the electric motor is less than or equal to a preset rotation speed, determining that a control algorithm to be used is a current control algorithm, and controlling, according to a current amplitude of the electric motor, the inverter to inject a current vector into the electric motor; and when the rotation speed of the electric motor is greater than the preset rotation speed, determining that the control algorithm to be used is a pulse control algorithm, and adjusting a duty cycle of a control signal of the inverter.

Description

Protection method and system of inverter and vehicle

Cross-reference to related applications

This application claims the priority of China Patent Application No. “201811003100.4”, submitted by BYD Co., Ltd. on August 30, 2018, with the application name “Inverter Protection Method and System and Vehicle”.

Technical field

The present application relates to the technical field of vehicles, and in particular, to a method and system for protecting an inverter, and a vehicle.

Background technique

During the control operation of the vehicle, for example, during the operation of the traction inverter of the rail train, due to the large inertia of the rail train and the multi-power distribution, when the motor is running at a low speed, a very small zero-crossing drive current is generated. As a result, the diode in the inverter cannot be turned on effectively, that is, it is turned off before it is fully turned on. When the motor is running at high speed, due to full load operation, the duty cycle of the power switch is almost 100%, especially when the bus voltage is relatively high. This low duty cycle on-state occurs frequently during low and high power operation. Therefore, the operation of the inverter in the related technology will adversely affect the power module, and in severe cases, it may even cause damage to the power module.

Summary of the Invention

This application is intended to solve at least one of the technical problems in the related technology. For this reason, the first object of the present application is to provide an inverter protection method, which can effectively prevent the traction inverter from being damaged due to the occurrence of a narrow driving pulse phenomenon.

A second object of the present application is to provide a protection system for an inverter.

A third object of the present application is to propose a vehicle.

A fourth object of the present application is to propose a non-transitory computer-readable storage medium.

To achieve the above object, the first aspect of the present application proposes a method for protecting an inverter. The inverter is used to drive a motor. The method includes the following steps: obtaining the rotation speed of the motor; When the speed is less than or equal to the preset speed, it is determined that the control algorithm to be used is a current control algorithm, and the inverter is controlled to inject a current vector into the motor according to the current amplitude of the motor; when the speed of the motor is greater than the When the preset speed is determined, the control algorithm to be used is determined as a pulse control algorithm, and the duty cycle of the control signal of the inverter is adjusted so that there is no narrow pulse in the control signal. The pulse width of the narrow pulse is less than a preset threshold.

According to the inverter protection method of the present application, the control algorithm to be used is determined by the motor rotation speed. When the rotation speed of the motor is less than or equal to a preset rotation speed, the control algorithm to be used is determined as a current control algorithm, and according to the current amplitude of the motor The value control inverter injects a current vector into the motor. When the speed of the motor is greater than a preset speed, the control algorithm to be used is determined as a pulse control algorithm, and the duty cycle of the control signal of the inverter is adjusted to make the control There are no narrow pulses in the signal. Therefore, the protection method in the embodiment of the present application can determine the control algorithm to be used to perform different control strategies on the inverter when different control algorithms are used, thereby effectively preventing the traction motor from operating in the full speed range The traction inverter is damaged due to the phenomenon of driving narrow pulses. Without changing the hardware circuit topology, only the software algorithm can improve the operation safety and reliability of the traction inverter.

To achieve the above object, a second aspect of the present application proposes an inverter protection system, including: an inverter, the inverter being connected to a motor to drive the motor; a control module, the control module and the The inverter is connected, and the control module is configured to obtain the speed of the motor; when the speed of the motor is less than or equal to a preset speed, determine that the control algorithm to be used is a current control algorithm, and The current amplitude of the motor controls the inverter to inject a current vector into the motor; when the speed of the motor is greater than the preset speed, determining that the control algorithm to be used is a pulse control algorithm, and The duty cycle of the control signal of the transformer is adjusted so that there is no narrow pulse in the control signal, wherein the pulse width of the narrow pulse is less than a preset threshold.

According to the inverter protection system of the present application, the motor is driven by the inverter, and the control module determines a control algorithm to be used based on the motor speed. When the speed of the motor is less than or equal to a preset speed, the control algorithm to be used is determined as a current. The control algorithm controls the inverter to inject a current vector into the motor according to the current amplitude of the motor. When the speed of the motor is greater than a preset speed, it is determined that the control algorithm to be used is a pulse control algorithm, and the control signal of the inverter is The duty cycle is adjusted so that there are no narrow pulses in the control signal. Therefore, the protection system in the embodiment of the present application can determine the control algorithm to be used to perform different control strategies on the inverter when different control algorithms are used, thereby effectively preventing the traction motor from running in the full speed range. The traction inverter is damaged due to the phenomenon of driving narrow pulses. Without changing the hardware circuit topology, only the software algorithm can improve the operation safety and reliability of the traction inverter.

To achieve the above object, a third aspect of the present application proposes a vehicle including a protection system according to the inverter.

Additional aspects and advantages of the present application will be given in part in the following description, part of which will become apparent from the following description, or be learned through practice of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and / or additional aspects and advantages of this application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

1 is a flowchart of a method for protecting an inverter according to an embodiment of the present application;

2 is a flowchart of a method for protecting an inverter according to another embodiment of the present application;

3 is a flowchart of a method for protecting an inverter according to another embodiment of the present application;

4 is a schematic block diagram of an inverter protection system according to an embodiment of the present application;

FIG. 5 is a schematic block diagram of a vehicle according to an embodiment of the present application.

detailed description

Hereinafter, embodiments of the present application will be described in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary, and are intended to explain the present application, and should not be construed as limiting the present application.

During the operation of the rail transit traction inverter, the narrow pulse of the power module is one of the important factors causing the failure of the power module. Among them, the narrow pulse phenomenon of a power module refers to a phenomenon in which an IGBT (Insulated Gate Bipolar Transistor) is not fully turned on and then turned off. When the IGBT or diode of the power module is not fully turned on and off, the amount of change di / dt is much larger than that when it is normally fully turned on and then turned off. Therefore, the IGBT unit will be greatly turned off. Voltage spikes cause large oscillations to the diode, which adversely affects the power module, causing IPM (Intelligent Power Module) faults. In severe cases, it can cause damage to the power module.

In the related art, in order to solve the above problems, generally adopted methods are: optimize the circuit topology in terms of hardware, reduce stray inductance in the circuit or reduce the amount of current di / dt to avoid thermal breakdown or high voltage breakdown; In terms of software, the algorithm to eliminate narrow pulses is used. When PWM (Pulse Width Modulation) is fully modulated, when a narrow pulse smaller than a certain threshold (such as 4us) appears in the output PWM waveform, it directly outputs 0 duty. ratio.

However, a problem in the related art is that the aforementioned software-based algorithm for eliminating narrow pulses cannot completely eliminate the effects of narrow pulses in the power module, which is not conducive to the safe driving of the power module. Moreover, in the IGBT driving narrow pulse elimination algorithm, there is a relatively obvious output voltage loss, which is not conducive to the output of the motor peak power.

Based on this, this application proposes an inverter protection method and system.

The protection method and system of the inverter according to the embodiments of the present application are described below with reference to the drawings.

FIG. 1 is a flowchart of a method for protecting an inverter according to an embodiment of the present application. Among them, the inverter is used to drive the motor. As shown in FIG. 1, the method for protecting an inverter in the embodiment of the present application includes the following steps:

S1: Get the speed of the motor.

It should be noted that, in the embodiment of the present application, the control algorithm may be determined by obtaining the rotation speed of the motor, where the control algorithm includes a current control algorithm and a pulse control algorithm.

S2: When the speed of the motor is less than or equal to the preset speed, the inverter is controlled to inject a current vector into the motor according to the current amplitude of the motor.

Among them, according to the current adjustment instruction, a table is looked up to determine the current amplitude of the motor.

It should be understood that during the operation of the vehicle, when the state of the vehicle needs to be changed, a current adjustment instruction is sent to look up the table according to the current adjustment instruction to determine the current amplitude of the motor, and then determine the current vector according to the current amplitude and inject it into the motor. In order to control the motor, the current control algorithm is defined as the current control algorithm, that is, when the speed of the motor is less than or equal to the preset speed, the control algorithm to be used is determined as the current control algorithm. , And control the inverter to inject a current vector into the motor according to the current amplitude of the current.

It should also be noted that the table for querying according to the current adjustment instruction can be obtained through the first offline test, that is, the correspondence between the current adjustment instruction and the current amplitude of the motor is obtained during the first offline test. After the current adjustment instruction is obtained during the running of the motor, the current amplitude of the motor can be determined by looking up the table.

The current vector may include a straight-axis current and a quadrature-axis current. The current adjustment instruction includes a straight-axis current reference value and a quadrature-axis current reference value, and the current amplitude of the motor is determined according to a straight-axis current reference value and a quadrature-axis current reference value look-up table.

Specifically, as shown in FIG. 2, injecting a current vector into the motor according to the current amplitude of the motor includes:

S201: When the current amplitude Is of the motor is less than the preset current threshold, the direct axis current reference value Idref of the current vector is set to the preset current threshold, and the quadrature axis current reference value Iqref of the current vector is set to the quadrature axis. Current setting value Iq_table.

The preset current threshold may be 10A.

Both the preset current threshold value and the quadrature axis current set value Iq_table can be obtained through a second offline test, that is, when the current amplitude Is of the motor is less than the preset current threshold value, the direct-axis current reference value Idref of the injected current vector The values of the reference current and the quadrature axis current Iqref are obtained by the second offline test. It should be noted that during the second offline test, the power model characteristics of the motor controller and the characteristics of the motor load need to be considered to ensure that the diodes in the power module of the motor controller have sufficient turn-on and reverse recovery time.

It should be noted that when the rail train is running at low speed or is coasting, there is a very small zero-crossing drive current due to inertia. In this case, in order to prevent IPM failure or damage to the power module caused by the oscillation of the reverse recovery voltage of the diode, the embodiment of the present application uses injection of a certain reactive current to avoid this risk. In the embodiment of the present application, the set value of the reactive current is a preset current threshold, that is, 10A.

S202: When the current amplitude Is of the motor is greater than or equal to a preset current threshold, set the direct axis current reference value Idref of the current vector to the direct axis current set value Id_table, and set the quadrature axis current reference value Iqref of the current vector Set to the quadrature axis current set value Iq_table. Among them, the set value Id_table of the direct current can be equal to or slightly greater than 10A

It should be understood that the direct axis current setting value Id_table and the quadrature axis current setting value Iq_table can also be obtained through the second offline test. In the second offline test, the motor control performance needs to be fully considered and established by the applied motor control algorithm. The relationship between the output torque of the motor and the control current of the quadrature axis and the quadrature axis determines the direct axis current setting value Id_table and the quadrature axis current setting value Iq_table.

In other words, when the current amplitude Is of the motor is greater than or equal to a preset current threshold, the motor controller power model characteristics and the motor load are guaranteed by injecting the motor with a direct axis current setting value Id_table and a quadrature axis current setting value Iq_table. In the case of characteristics, to meet the control requirements of the current adjustment instruction, and when the current amplitude Is of the motor is less than the preset current threshold, the IPM caused by the reverse recovery voltage of the diode is prevented by injecting the preset current threshold into the motor. Failure or damage to the power module, and the quadrature axis current set value Iq_table is injected to ensure the characteristics of the motor controller power model and the characteristics of the motor load.

Specifically, the speed of the motor is obtained. When the speed of the motor is less than or equal to the preset speed, the control algorithm to be used is determined as a current control algorithm, and the magnitude relationship between the current amplitude Is of the motor and the preset current threshold is determined. When the current amplitude Is is smaller than the preset current threshold, that is, when Is <10A, the DC current reference value Idref of the current vector is set to the preset current threshold value, and the quadrature axis current reference value Iqref of the current vector is set to Quadrature axis current set value Iq_table, that is Idref = 10A and Iqref = Iq_table; when the motor current amplitude Is is greater than or equal to the preset current threshold, that is Is≥10A, set the direct axis current reference value Idref of the current vector It is the direct axis current setting value Id_table, and the quadrature axis current reference value Iqref of the current vector is set to the quadrature axis current setting value Iq_table, that is, Idref = Id_table and Iqref = Iq_table.

Therefore, the embodiment of the present application can inject reactive current into the power module when the motor is running at a low speed to ensure that the diode in the power module has sufficient on-time, thereby reducing the adverse effect of the small zero-crossing current on the diode. No motor torque is output.

S3: When the speed of the motor is greater than a preset speed, the duty cycle of the control signal of the inverter is adjusted so that there is no narrow pulse in the control signal. The pulse width of the narrow pulse is smaller than a preset threshold.

It should be noted that the preset threshold is to prevent the smaller duty cycle from causing damage to the power module of the motor controller, because when the smaller duty cycle is applied to the power module, the IGBT will be turned on / off before it is completed. When it is turned off, it enters the next turn-off / turn-on action, which causes overvoltage and damages the power module. Therefore, the embodiment of the present application can avoid the risk brought by the narrow pulse by detecting the magnitude of the duty cycle and processing it. Among them, the preset threshold is a time threshold to avoid the IGBT not being fully turned on / off. Since this process is an adjustment of the pulse width, it is defined as a pulse control algorithm.

It should also be noted that the duty cycle is the ratio of the IGBT on time to the total time in a control cycle; the pulse includes positive and negative pulses, and the pulse width of the positive pulse is the ratio of the IGBT on time to the total time The pulse width of the negative pulse is the ratio of the IGBT off time to the total time; the preset threshold has a corresponding preset pulse width within a control period, so the narrow pulse is a pulse with a pulse width smaller than the preset pulse width. Further, the duty cycle of the control signal of the inverter is adjusted so that there are no narrow pulses in the control signal, that is, there are no pulses greater than zero and less than a preset pulse width in a control cycle, including positive pulses. Pulse and negative pulse, specifically, the pulse width of the positive pulse and the pulse width of the negative pulse may be greater than or equal to the preset pulse width within a control period, or there may be only positive pulse or only negative pulse, but the pulse width of the positive pulse The pulse widths of the negative pulse and the negative pulse cannot be in a pulse width range greater than zero and less than a preset pulse width. Therefore, narrow pulses can be avoided by making no pulse having a pulse width greater than zero and less than a preset pulse width in the control period.

It should be understood that the inverter includes a plurality of sets of bridge arms, wherein each set of bridge arms includes two upper and lower IGBTs, and the two upper and lower IGBTs in each group of bridge arms are not turned on at the same time. Taking a three-phase bridge inverter as an example, a three-phase bridge inverter may include three groups of bridge arms connected in parallel, that is, six IGBTs. When each group of bridge arms operates, the upper and lower two IGBTs are turned on alternately. Based on this, by controlling the duty cycle of the control signal of any IGBT in the inverter, it is possible to control multiple IGBTs in the entire inverter at the same time.

As shown in FIG. 3, adjusting the duty cycle of the control signal of the inverter includes:

S301: Obtain the duty cycle of the control signal.

S302: When the duty cycle is greater than the first preset threshold, adjust the duty cycle of the control signal input to the inverter to 100%.

Wherein, the first preset threshold value is a difference of 100% minus a preset threshold value, where a is a value greater than 0 and less than 1. a is preferably 1/2.

S303: When the duty cycle is greater than or equal to the second preset threshold and less than or equal to the first preset threshold, adjust the duty cycle of the control signal input to the inverter to the second preset threshold.

Similarly, when the duty cycle is less than the third preset threshold, the duty cycle of the control signal input to the inverter is adjusted to 0%; when the duty cycle is greater than or equal to the third preset threshold and less than or equal to the preset threshold When setting the threshold, the duty cycle of the control signal input to the inverter is adjusted to a preset threshold.

Wherein, the second preset threshold value is a difference of 100% minus the preset threshold value, and the third preset threshold value is a value of 0% plus a preset threshold value.

It should be noted that when the rail train is running at high speed and high power, the duty cycle of the power module is about 100%. When the opening time of a bridge arm is too long, a narrow pulse may occur in the closing process of the bridge arm. At this time, the IGBT module has a risk of turning on and off with a narrow pulse. The embodiment of the present application adopts a narrow pulse avoidance strategy, that is, when the pulse width is less than a preset threshold, the duty cycle is adjusted to 100% or the pulse width is adjusted. Adjust to a preset pulse width (adjust the duty cycle to a second preset threshold), thereby eliminating the phenomenon of narrow pulses and avoiding damage to power modules by narrow pulses. While eliminating the narrow pulses of the IGBT, it also minimizes its impact on the motor output power.

Specifically, the rotation speed of the motor is obtained. When the rotation speed of the motor is greater than a preset rotation speed, the control algorithm to be used is determined as a pulse control algorithm, and the duty cycle Duty0 of the control signal is obtained. When the duty cycle Duty0 is greater than the first preset threshold When adjusting the duty cycle Duty of the control signal input to the inverter to 100%, that is, when the pulse width of the positive pulse is greater than the first preset threshold, the pulse width of the negative pulse will be less than the preset pulse width and the positive pulse The duty cycle corresponding to the pulse width is closer to 100%. At this time, by adjusting the duty cycle so that there are no negative pulses in the control period, to prevent narrow pulses in the control period. In the embodiment of the present application, the first The preset threshold is 100% minus a preset threshold difference. For example, a = 1/2, when Duty0> 98%, Duty = 100%; when the duty cycle Duty0 is greater than or equal to the second preset threshold When the threshold is set and is less than or equal to the first preset threshold, the duty cycle of the control signal input to the inverter is adjusted to the second preset threshold, that is, when the pulse width of the positive pulse is larger than the second preset threshold and smaller than the first preset threshold Negative pulse at a preset threshold The pulse width is smaller than the preset pulse width and the pulse width of the negative pulse is closer to the preset pulse width. At this time, by adjusting the duty cycle, the pulse width of the negative pulse in the control period is equal to the preset pulse width to prevent the control period. A narrow pulse appears, where the second preset threshold is 100% minus the preset threshold, that is, when 98%> Duty0> 96%, Duty = 96%.

When the duty cycle is less than the third preset threshold, that is, the pulse width of the positive pulse is less than the preset pulse width and the duty cycle corresponding to the pulse width of the negative pulse is closer to 100%, at this time, the control is made by adjusting the duty cycle There are no positive pulses in the period to prevent narrow pulses in the control period; when the duty cycle is greater than or equal to the third preset threshold and less than the preset threshold, the pulse width of the positive pulse is less than the preset pulse width and the When the pulse width is closer to the preset pulse width, the duty cycle of the control signal input to the inverter is adjusted to a preset threshold value to prevent narrow pulses from appearing in the control period.

It should be understood that when the duty cycle is greater than a preset threshold value and less than a second preset threshold value, the duty cycle may not be adjusted.

The preset speed can be 300 rpm.

Therefore, the embodiment of the present application can adopt a narrow pulse compromise and avoidance strategy when the motor is running at high speed, while reducing or avoiding narrow pulses driven by the IGBT, it does not bring obvious voltage loss and reduce the impact on the peak power output of the motor. .

In summary, according to the inverter protection method in the embodiment of the present application, the control algorithm to be used is determined by the motor speed. When the speed of the motor is less than or equal to a preset speed, the control algorithm to be used is determined as a current control algorithm. , And control the inverter to inject a current vector into the motor according to the current amplitude of the motor. When the speed of the motor is greater than a preset speed, determine that the control algorithm to be used is a pulse control algorithm, and occupy the duty of the inverter's control signal. The ratio is adjusted so that there are no narrow pulses in the control signal. Therefore, the protection method in the embodiment of the present application can determine the control algorithm to be used to perform different control strategies on the inverter when different control algorithms are used, thereby effectively preventing the traction motor from operating in the full speed range The traction inverter is damaged due to the phenomenon of driving narrow pulses. Without changing the hardware circuit topology, only the software algorithm can improve the operation safety and reliability of the traction inverter.

In order to implement the above embodiments, the present application also proposes a protection system for an inverter.

FIG. 4 is a schematic block diagram of a protection system for an inverter according to an embodiment of the present application. As shown in FIG. 4, the inverter protection system 100 includes: an inverter 10 and a control module 20.

The inverter 10 is connected to the motor to drive the motor, and the control module 20 is connected to the inverter 10. The control module 20 is used to obtain the speed of the motor; when the speed of the motor is less than or equal to a preset speed, determine the speed to be used The control algorithm is a current control algorithm and controls the inverter to inject a current vector into the motor according to the current amplitude of the motor. When the speed of the motor is greater than a preset speed, it is determined that the control algorithm to be used is a pulse control algorithm, and the inverter is The duty cycle of the control signal is adjusted so that there is no narrow pulse in the control signal, where the pulse width of the narrow pulse is less than a preset threshold.

The control module 20 is configured to obtain the direct axis current reference value and the quadrature axis current reference value of the current vector according to the current adjustment instruction, and calculate the current amplitude of the motor according to the direct axis current reference value and the quadrature axis current reference value; when the motor current When the amplitude is smaller than the preset current threshold, the direct axis current reference value of the current vector is set to the preset current threshold value, and the quadrature axis current reference value of the current vector is set to the quadrature axis current set value; when the current of the motor is When the amplitude is greater than or equal to the preset current threshold, the direct axis current reference value of the current vector is set as the direct axis current set value, and the quadrature axis current reference value of the current vector is set as the cross axis current set value.

The control module 20 is configured to obtain the duty cycle of the control signal; when the duty cycle is greater than the first preset threshold, adjust the duty cycle of the control signal input to the inverter to 100%; when the duty cycle is greater than or When the second preset threshold is equal to and less than or equal to the first preset threshold, the duty cycle of the control signal input to the inverter is adjusted to the second preset threshold, where the second preset threshold is 100% minus Difference of preset threshold.

The control module 20 is configured to adjust the duty ratio of the control signal input to the inverter to 0% when the duty ratio is less than the third preset threshold; when the duty ratio is greater than or equal to the third preset threshold and less than Or equal to the preset threshold, the duty cycle of the control signal input to the inverter is adjusted to the preset threshold; wherein the third preset threshold is a value of 0% plus a times the preset threshold, a is greater than A value of 0 and less than 1.

The first preset threshold is a difference of 100% minus a preset threshold, where a is a value greater than 0 and less than 1.

The control module 20 is further configured to perform a table lookup according to the current adjustment instruction to determine the current amplitude of the motor.

It should be noted that the foregoing explanation of the embodiment of the method for protecting an inverter is also applicable to the protection system of the inverter of this embodiment, and details are not described herein again.

In order to implement the above embodiments, a vehicle is further provided in the present application. As shown in FIG. 5, a vehicle 200 provided in the embodiment of the present application includes a protection system 100 for an inverter.

In the description of this specification, the description with reference to the terms “one embodiment”, “some embodiments”, “examples”, “specific examples”, or “some examples” and the like means specific features described in conjunction with the embodiments or examples , Structure, material, or characteristic is included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of the different embodiments or examples without conflicting one another.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality" is at least two, for example, two, three, etc., unless it is specifically and specifically defined otherwise.

Any process or method description in a flowchart or otherwise described herein can be understood as representing a module, fragment, or portion of code that includes one or more executable instructions for implementing steps of a custom logic function or process And, the scope of the preferred embodiments of this application includes additional implementations in which the functions may be performed out of the order shown or discussed, including performing the functions in a substantially simultaneous manner or in the reverse order according to the functions involved, which should It is understood by those skilled in the art to which the embodiments of the present application pertain.

Logic and / or steps represented in a flowchart or otherwise described herein, for example, a sequenced list of executable instructions that may be considered to implement a logical function, may be embodied in any computer-readable medium, For use by, or in combination with, an instruction execution system, device, or device (such as a computer-based system, a system that includes a processor, or another system that can fetch and execute instructions from an instruction execution system, device, or device) Or equipment. For the purposes of this specification, a "computer-readable medium" may be any device that can contain, store, communicate, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: electrical connections (electronic devices) with one or more wirings, portable computer disk cartridges (magnetic devices), random access memory (RAM), Read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program can be printed, because, for example, by optically scanning the paper or other medium, followed by editing, interpretation, or other suitable Processing to obtain the program electronically and then store it in computer memory.

It should be understood that each part of the application may be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods may be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it may be implemented using any one or a combination of the following techniques known in the art: Discrete logic circuits with logic gates for implementing logic functions on data signals Logic circuits, ASICs with suitable combinational logic gate circuits, programmable gate arrays (PGA), field programmable gate arrays (FPGA), etc.

A person of ordinary skill in the art can understand that all or part of the steps carried by the methods in the foregoing embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium. The program is When executed, one or a combination of the steps of the method embodiment is included.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing module, or each unit may exist separately physically, or two or more units may be integrated into one module. The above integrated modules may be implemented in the form of hardware or software functional modules. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

The aforementioned storage medium may be a read-only memory, a magnetic disk, or an optical disk. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations on the present application. Those skilled in the art may, within the scope of the present application, understand the above. Embodiments are subject to change, modification, substitution, and modification.

Claims

An inverter protection method is characterized in that the inverter is used to drive a motor, and the protection method includes the following steps:

Obtaining the rotation speed of the motor;

When the rotation speed of the motor is less than or equal to a preset rotation speed, controlling the inverter to inject a current vector into the motor according to a current adjustment instruction;

When the rotation speed of the motor is greater than the preset rotation speed, adjusting the duty cycle of the control signal of the inverter so that there is no narrow pulse in the control signal, wherein the pulse width of the narrow pulse Less than a preset threshold.
The method for protecting an inverter according to claim 1, wherein the controlling the inverter to inject a current vector into the motor according to a current adjustment instruction comprises:

Obtaining a direct axis current reference value and a quadrature axis current reference value of a current vector according to the current adjustment instruction, and calculating a current amplitude of the motor according to the direct axis current reference value and the quadrature axis current reference value;

When the current amplitude of the motor is less than a preset current threshold value, a direct axis current reference value of the current vector is set to the preset current threshold value, and a quadrature axis current reference value of the current vector is set Set value for quadrature axis current;

When the current amplitude of the motor is greater than or equal to a preset current threshold, setting a direct axis current reference value of the current vector to the direct axis current setting value, and setting a quadrature axis current of the current vector The reference value is set as the quadrature axis current set value.
The method for protecting an inverter according to claim 1 or 2, wherein adjusting the duty cycle of a control signal input to the inverter comprises:

Obtaining a duty cycle of the control signal;

When the duty cycle is greater than a first preset threshold, adjusting the duty cycle of the control signal input to the inverter to 100%;

When the duty cycle is greater than or equal to the second preset threshold and less than or equal to the first preset threshold, adjusting the duty cycle of the control signal input to the inverter to the A second preset threshold, wherein the second preset threshold is 100% minus a difference between the preset thresholds.
The method for protecting an inverter according to claim 3, further comprising:

When the duty cycle is less than a third preset threshold, adjusting the duty cycle of the control signal input to the inverter to 0%;

When the duty cycle is greater than or equal to the third preset threshold and less than or equal to the preset threshold, adjusting the duty cycle of the control signal input to the inverter to the preset Threshold

The third preset threshold is a value of 0% plus a times the preset threshold, and a is a value greater than 0 and less than 1.
The method for protecting an inverter according to claim 3, wherein the first preset threshold value is a difference of 100% minus the preset threshold value a, wherein a is greater than 0 and less than The value of 1.
The method for protecting an inverter according to any one of claims 1-5, further comprising:

Perform a look-up table according to the current adjustment instruction to determine the current amplitude of the motor.
An inverter protection system includes:

An inverter connected to the motor to drive the motor;

A control module, which is connected to the inverter, and the control module is configured to obtain the rotation speed of the motor; when the rotation speed of the motor is less than or equal to a preset rotation speed, according to the current amplitude of the motor The value controls the inverter to inject a current vector into the motor; when the speed of the motor is greater than the preset speed, the duty cycle of the control signal of the inverter is adjusted so that the control signal is not There are narrow pulses, wherein the pulse width of the narrow pulses is less than a preset threshold.
The protection system for an inverter according to claim 7, wherein the control module is further configured to:

Obtaining a direct axis current reference value and a quadrature axis current reference value of a current vector according to the current adjustment instruction, and calculating a current amplitude of the motor according to the direct axis current reference value and the quadrature axis current reference value;

When the current amplitude of the motor is less than a preset current threshold value, a direct axis current reference value of the current vector is set to the preset current threshold value, and a quadrature axis current reference value of the current vector is set Set value for quadrature axis current;

When the current amplitude of the motor is greater than or equal to a preset current threshold, setting a direct axis current reference value of the current vector to the direct axis current setting value, and setting a quadrature axis current of the current vector The reference value is set as the quadrature axis current set value.
The protection system for an inverter according to claim 7 or 8, wherein the control module is further configured to:

Obtaining a duty cycle of the control signal;

When the duty cycle is greater than a first preset threshold, adjusting the duty cycle of the control signal input to the inverter to 100%;

When the duty cycle is greater than or equal to the second preset threshold and less than or equal to the first preset threshold, adjusting the duty cycle of the control signal input to the inverter to the A second preset threshold, wherein the second preset threshold is 100% minus a difference between the preset thresholds.
The protection system for an inverter according to claim 9, wherein the control module is further configured to:

When the duty cycle is less than a third preset threshold, adjusting the duty cycle of the control signal input to the inverter to 0%;

When the duty cycle is greater than or equal to the third preset threshold and less than or equal to the preset threshold, adjusting the duty cycle of the control signal input to the inverter to the preset Threshold

The third preset threshold is a value of 0% plus a times the preset threshold, and a is a value greater than 0 and less than 1.
The protection system for an inverter according to claim 9, wherein the first preset threshold value is a difference of 100% minus the preset threshold value a, wherein a is greater than 0 and less than The value of 1.
The protection system for an inverter according to any one of claims 7-11, wherein the control module is further configured to:

Perform a look-up table according to the current adjustment instruction to determine the current amplitude of the motor.
A vehicle, comprising a protection system for an inverter according to any one of claims 7-12.