CN112034384B - Method, apparatus and computer readable storage medium for identifying motor system short circuit - Google Patents
Method, apparatus and computer readable storage medium for identifying motor system short circuit Download PDFInfo
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- CN112034384B CN112034384B CN202010764835.XA CN202010764835A CN112034384B CN 112034384 B CN112034384 B CN 112034384B CN 202010764835 A CN202010764835 A CN 202010764835A CN 112034384 B CN112034384 B CN 112034384B
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- 230000002159 abnormal effect Effects 0.000 abstract description 8
- 238000001514 detection method Methods 0.000 description 14
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
- B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
- G01R31/343—Testing dynamo-electric machines in operation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
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- Y02T10/72—Electric energy management in electromobility
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Abstract
The invention provides a method, equipment and a computer readable storage medium for identifying a short circuit of a motor system, wherein the method is applied to the technical field of new energy automobiles; inputting preset pulse signals to control ends of n bridge arms in the inverter, and conducting any one or a plurality of first switching tubes; turning off the first switching tube; turning on all the second switching tubes; turning off all the second switching tubes to form a switching period; and detecting the current of the motor winding in the switching period, and judging whether the motor system has short ground or not according to the comparison of the detected current value and a preset current threshold value. The invention can accurately and effectively identify the abnormal operation of the motor controller of the new energy automobile caused by the short circuit fault, can determine the position range of the short fault point, and does not need to increase the hardware cost.
Description
Technical Field
The invention relates to the technical field of new energy automobiles, in particular to a method and equipment for identifying short circuit of a motor system and a computer readable storage medium.
Background
With the rapid development of new energy automobiles with the advancement of battery and power electronic technology, the functional complexity of the automobiles is increasingly improved, and the requirements of regulations on safety, environmental protection and energy conservation are increasingly strict, so that the requirements of comfortable, flexible and personalized clients are quite different.
The motor controller output phase is shorted to the housing or motor windings are insulated abnormally, typically using a change in power to identify whether the controller is abnormal. Specifically, before operation, a power supply, a cable, a switching tube, a motor winding and a machine shell (ground) form a loop through the action of an inverter switch, and whether the winding has current or not is detected to judge whether to output short ground or not.
The reference point of the power supply potential of the motor controller is identified by a shell (ground), and is different from a high-voltage power supply system of a new energy automobile.
In order to meet the safety requirements of new energy automobiles and improve the electromagnetic compatibility (EMC) of the system, a Y capacitor is commonly connected in series between the positive electrode of the high-voltage power battery and the automobile body as well as between the negative electrode of the high-voltage power battery and the automobile body so as to filter common-mode interference signals. The Y-capacitor typically receives a small nominal current in order to accommodate cost and volume requirements. When one phase of the alternating current side of the inverter is short, or the insulation of one phase winding of the motor is abnormal, the motor controller forms a power loop by the battery, the bus capacitor, the switching tube and the motor, and forms a power loop by the battery, the bus capacitor, the switching tube, the motor, the Y capacitor and the casing (ground). Therefore, oscillation current is formed in the Y capacitor, but the motor controller or the whole vehicle cannot detect the fault, and the Y capacitor, the fuse, the Hall and other devices can be burnt out by long-time large current.
The detection method mainly comprises a hardware detection device and a software detection method aiming at the output single-phase short circuit to ground fault. The typical method of hardware is that a sensing device is connected in series with a Y capacitor branch circuit, or the voltage change of the Y capacitor is detected, or the characteristic quantity of an output side is detected, so that fault detection is realized. The typical method of software is to output a three-phase current imbalance method by adopting a motor controller.
At present, the prior art has the following problems:
first, in the hardware detection device in the prior art, detection needs to be implemented by means of increasing bandwidth or increasing sampling frequency, and the hardware scheme has high reliability, and increases cost no matter increasing bandwidth or increasing sampling frequency.
Secondly, in the software detection method, the existing schemes are fixed thresholds, the running state of the whole vehicle is not considered, the threshold setting requirement is very high, false alarm and missing alarm phenomena are easy to occur, specifically, the three-phase current imbalance is a scheme for detecting the vehicle in real time in running, but because the thresholds are relatively fixed, the method cannot adapt to the characteristic of working condition change, false alarm is easy to occur under certain working conditions, such as a large torque working condition, and false alarm is easy to occur under certain working conditions, such as a low voltage small torque working condition.
The foregoing is provided merely for the purpose of facilitating understanding of the technical solutions of the present invention and is not intended to represent an admission that the foregoing is prior art.
Disclosure of Invention
The invention mainly aims to provide a method, equipment and a computer readable storage medium for identifying a short circuit of a motor system, and aims to solve the technical problem of how to effectively identify abnormal operation of a motor controller of a new energy automobile caused by short circuit faults.
In order to achieve the above object, the present invention provides a method for identifying a short circuit of a motor system, the motor system including an inverter and a motor; the inverter comprises n bridge arms, each bridge arm comprises a first switching tube and a second switching tube, the motor comprises n motor windings, the n motor windings are connected with the n bridge arms in a one-to-one correspondence manner, and n is a positive integer, and the method is characterized by comprising the following steps:
inputting preset pulse signals to control ends of n bridge arms in the inverter, and conducting any one or a plurality of first switching tubes; turning off the first switching tube; turning on all the second switching tubes; turning off all the second switching tubes to form a switching cycle,
and detecting the current of the motor winding in the switching period, and judging whether the motor system has short ground or not according to the comparison of the detected current value and a preset current threshold value.
Preferably, when the first switching tube is not fully turned on in a state that the motor system is not short-circuited after one switching period is passed and preliminary judgment is made, the turned-on first switching tube is turned off in a subsequent switching period, and whether the motor system is short-circuited is judged again.
Preferably, in a state that the motor system is confirmed to have a short ground in a certain switching period, if the first switching tube in the switching period is a plurality of conducting switches, a plurality of switching periods are circulated again, and only the first switching tube which is not conducting is conducted in each subsequent switching period until a phase in which the short ground is confirmed to be located.
Preferably, said switching on of only said first switching tube which is not turned on in each subsequent switching cycle comprises: the range of the first switching tube which is not conducted is gradually reduced in each switching period.
Preferably, in the preset M preset pulse signals, when the number of times that the detected current value is continuously greater than the current threshold reaches a preset number of times threshold, it is determined that a short-to-ground phase exists in the motor system, and M is a positive integer greater than 1.
Preferably, in the preset M preset pulse signals, when the number of times that the detected current value is continuously greater than the preset current threshold reaches a preset number of times threshold, it is determined that a short ground exists in the motor system.
Preferably, in the preset M preset pulse signals, when the detected current value is greater than the preset current threshold value, determining that the motor system is pre-short;
counting the times of occurrence of pre-short lands of the motor system under the continuous action of the preset pulse signals;
and when the occurrence number of the pre-short ground is larger than a preset number threshold, judging that the short position is positioned in the phase where the first switching tube which is not conducted is positioned.
Preferably, the preset pulse signal includes a first preset pulse signal and a second preset pulse signal, the first preset pulse signal is used for controlling the first switching tube of the bridge arm to be turned on according to a first preset mode and the second switching tube to be turned off according to the first preset mode, and the second preset pulse signal is used for controlling the second switching tube of the bridge arm to be turned on according to a second preset mode and the first switching tube to be turned off according to the second preset mode.
In addition, in order to achieve the above object, the present invention also provides a motor system short circuit identification device, which includes a memory and a processor, wherein the memory stores a computer program that can run on the processor, and the processor executes the computer program to implement the steps of the motor system operation abnormality method described above.
In addition, to achieve the above object, the present invention also proposes a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the method for identifying a motor system short circuit as described above.
The identification method, the equipment and the computer readable storage medium for the short circuit of the motor system have the beneficial effects that any one or a plurality of first switching tubes are conducted by inputting preset pulse signals to the control ends of n bridge arms in the inverter; turning off the first switching tube; turning on all the second switching tubes; turning off all the second switching tubes to form a switching period; and finally, detecting the current of the motor winding in the switching period, and comparing the detected current value with a preset current threshold value to judge whether the motor system has short ground, so that the abnormal operation of the motor controller of the new energy automobile caused by short circuit fault can be accurately and effectively identified, the position range of the short fault point can be determined, and the hardware cost is not required to be increased.
Drawings
FIG. 1 is a flow chart of a method for identifying a motor system short circuit according to the present invention;
fig. 2 is a schematic circuit diagram of a method for identifying a short circuit of a motor system according to the present invention;
FIG. 3 is a schematic waveform diagram of a preset pulse signal according to an embodiment of the present invention;
FIG. 4a is a schematic flow chart of a motor system fault detection method according to the present invention;
FIG. 4b is a logic flow diagram of a motor system fault detection method according to the present invention;
FIG. 5 is a schematic diagram showing a first embodiment of a switch state according to the present invention;
FIG. 6 is a schematic diagram of a second embodiment of the switch state of the present invention;
fig. 7 is a schematic state diagram of each bridge arm switching tube of the inverter under the action of a preset pulse signal when the motor system of the invention is a three-phase motor system;
fig. 8 is a schematic block diagram of a motor system short circuit identification method apparatus in an embodiment of the invention.
The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
In order to solve the above technical problems, the present embodiment provides a method for identifying a short circuit of a motor system, and referring to fig. 1, fig. 1 is a flow chart of a method for identifying a short circuit of a motor system according to an embodiment of the present invention, and the method can be applied to a real-time scenario of a motor running process of a new energy automobile.
In this embodiment, corresponding to the structural block diagram shown in fig. 2, the motor system includes a motor controller and a motor; the motor controller comprises an inverter, wherein the inverter comprises n bridge arms, n is a positive integer, each bridge arm comprises a first switching tube and a second switching tube, the motor comprises n motor windings, and the n motor windings are in one-to-one correspondence connection with the n bridge arms;
it can be understood that the first switching tube is an upper bridge arm (lower bridge arm) switching tube, and the second switching tube is a lower bridge arm (upper bridge arm) switching tube.
Fig. 2 is a block diagram of a power system of a new energy automobile, and fig. 2 is a block diagram of a power system of a new energy automobile, which includes a power battery 1, a PN cable, an EMC filter unit 3, a bus bar supporting capacitor 4, an inverter bridge 5, an AC hall 6, an AC cable 7 (the AC cable 7 is composed of a cable 71 and a cable 72 … cable 7n in fig. 2), a motor 8 and a vehicle body 9. Wherein the PN cable is composed of a bus positive cable 21 and a bus negative cable 22. The EMC filter unit 3 is composed of a bus positive side Y capacitor 31, a bus negative side Y capacitor 32, and a Y capacitor ground 33, wherein the Y capacitor is a safety capacitor. The inverter bridge 5 consists of a motor controller shell 51, an upper bridge switching tube 52, a lower bridge switching tube 53, an output port 54 and a motor controller shell grounding end 55, wherein the upper bridge switching tube 52 and the lower bridge switching tube 53 respectively consist of n switching tubes (n is more than or equal to 2), the numbers of the upper bridge switching tube 52 are 521 to 52n in sequence, and the numbers of the lower bridge switching tube 53 are 531 to 53n in sequence; wherein the output port 54 is composed of n output terminals numbered 541 to 54n in order. The AC cable 7 is composed of n cables, one end of which is connected with the output port 54 of the inverter bridge 5, one end of which is connected with the port 83 of the motor 8, and the serial numbers are 831 to 83n in sequence. The motor 8 consists of a motor shell 81, windings, a motor port 83 and a motor shell grounding end 84, wherein the windings 82 are divided into n phases, and the numbers are 821 to 82n in sequence; wherein the motor port 83 is composed of n terminals, numbered 831 to 83n in sequence. The Y capacitor ground 33, the motor controller housing 51 ground 55, and the motor housing 81 ground 84 are connected to the vehicle body 9, respectively.
The specific connection mode of fig. 2 is as follows: the positive pole of the power battery 1 is connected with a bus positive cable 21, and the negative pole of the power battery 1 is connected with a bus negative cable 22. The two ends of the bus positive side Y capacitor 31 are respectively connected with the bus positive cable 21 and the vehicle body 9, and the two ends of the bus negative side Y capacitor 32 are respectively connected with the bus negative cable 22 and the vehicle body 9. The two ends of the bus bar supporting capacitor 4 are respectively connected with a bus bar positive cable 21 and a bus bar negative cable 22. The collector electrode C of the upper bridge 52 of the inverter bridge 5 is commonly connected to the bus positive cable 21, the emitter electrode E of the lower bridge 53 of the inverter bridge 5 is commonly connected to the bus negative cable 22, and the emitter electrode E of the upper bridge 52 of the inverter bridge 5 and the collector electrode C, AC cable 7 of the lower bridge 53 of the inverter bridge 5 are respectively in one-to-one correspondence. One end of the AC cable 7 is correspondingly connected to the output port 54 of the inverter bridge 5, and the other end is correspondingly connected to the motor port 83. The hall 6 is in turn connected across an AC cable 7.
The power battery 1 is responsible for supplying electric energy and feeding back stored electric energy. The PN cable is responsible for connecting the power battery 1 and the inverter bridge 5 as a path for electric energy transmission. The Y-capacitors (31, 32) provide a low impedance path for system common mode interference. The bus bar support capacitor 4 serves to smooth the bus bar voltage, store energy, and provide a minimum path for the inverter bridge 5. The inverter bridge 5 functions to convert direct current into alternating current for driving the motor 8, or to convert alternating current into direct current for feeding back energy generated by the motor 8 to the power battery 1. The hall 6 functions to sample the current in the output winding for control of the inverter bridge 5. The AC cable 7 is responsible for connecting the inverter bridge 5 and the motor 8, providing a path for power transmission. The motor 8 performs energy conversion transposition to convert electric energy into mechanical energy or to convert mechanical energy into electric energy. The vehicle body 9 is used for mounting power train equipment and serves as an electrical connection.
Based on the circuit structure shown in fig. 2, the method for identifying the short circuit of the motor system in this embodiment includes:
step S10: inputting preset pulse signals to control ends of n bridge arms in the inverter, and conducting any one or a plurality of first switching tubes; turning off the first switching tube; turning on all the second switching tubes; turning off all the second switching tubes to form a switching period;
it should be noted that, referring to fig. 3, the preset pulse signal includes a first preset pulse signal and a second preset pulse signal, where the first preset pulse signal is used to control the first switching tube of the bridge arm to be turned on according to a first preset manner, the second switching tube to be turned off according to a first preset manner, and the second preset pulse signal is used to control the second switching tube of the bridge arm to be turned on according to a second preset manner, and the first switching tube to be turned off according to a second preset manner.
The present embodiment can be divided into two switching modes: namely, when the first switching tube is an upper bridge switching tube, the second switching tube is a lower bridge switching tube; (mode II) when the first switching tube is a lower bridge switching tube, the second switching tube is an upper bridge switching tube;
in the specific implementation, the inverter lasts for a plurality of switching cycles, and the first switching tubes of any i bridge arms and the second switching tubes of all bridge arms in each switching cycle are in complementary actions, wherein i is a positive integer, and i is more than or equal to 1 and less than or equal to n-1.
Step S20: and detecting the current of the motor winding in the switching period, and judging whether the motor system has short ground or not according to the comparison of the detected current value and a preset current threshold value.
In a specific implementation, the current of each motor winding is detected, and in the step of detecting the current of each motor winding, the following sub-steps are preferably performed:
substep S21: detecting the current of the motor windings corresponding to the bridge arms except the i bridge arms in the n bridge arms, and comparing the detected current value with a preset current threshold value;
if there are two cases of comparison results, the sub-step S22 and the sub-step S23 are respectively corresponding to:
substep S22: judging that a short-to-ground phase exists in the motor system when the number of times that the detected current value is continuously larger than the preset current threshold reaches a preset number of times threshold in preset M preset pulse signals (M is a positive integer larger than 1); and outputting a short-circuit signal;
specifically, referring to fig. 4a and fig. 4b (fig. 4b is a signal logic diagram of a UVW phase of a three-phase motor system as an example), in a preset M preset pulse signals, when the detected current value is greater than the preset current threshold, determining that the motor system is pre-shorted; counting the times of occurrence of pre-short lands of the motor system under the continuous action of the preset pulse signals; and when the occurrence number of the pre-short ground is larger than a preset number threshold, judging that the short position is positioned in the phase where the first switching tube which is not conducted is positioned.
It should be noted that, referring to fig. 4b, the meaning of "pre-short" herein means that the motor system may be short-circuited; in a specific implementation of this embodiment, if the number of times of occurrence of the "pre-short" reaches a preset number of times, that is, a preset number of times threshold NIT; continuously accumulating nit=m times in the event that the threshold is exceeded, indicates that the motor system must experience a short-circuit phenomenon. The preset number of times threshold NIT (of the pre-short) of this embodiment is 10 times, and if the threshold is exceeded, the short fault is reported only after accumulation of 10 times.
Substep 23: and outputting a motor system non-short-circuit signal when the times of continuously detecting that the obtained current value is larger than the preset current threshold value in the preset M preset pulse signals do not reach the preset times threshold value.
Further, after the step of detecting the current of the motor winding, if it is determined that the motor system does not have a short-circuit phase (i.e., in the case of sub-step 23) according to the detected current value, that is, when the first switching tube is not fully turned on in a state in which one of the switching periods is passed and the motor system is primarily determined to have no short-circuit, the first switching tube that is turned on is turned off in a subsequent switching period, and then it is determined again whether the motor system has a short-circuit, specifically the following steps are performed:
step S30: a plurality of switching periods are continued, and in each switching period, any j first switching tubes in the first switching tubes of the remaining n-i bridge arms in the inverter and second switching tubes of all n bridge arms in the inverter are in complementary action; wherein j is a positive integer and satisfies 1.ltoreq.j < n-i;
the process of the step of the complementary actions of any j first switching tubes in the first switching tubes of the remaining n-i bridge arms in the inverter and the second switching tubes of all n bridge arms in the inverter in the specific implementation is as follows: and inputting the first preset pulse signals to the j bridge arms, inputting the second preset pulse signals to all the bridge arms of the inverter, detecting the currents of motor windings corresponding to the j bridge arms, and judging whether a short-to-ground phase exists in the motor system according to the detected current values.
It can be understood that the stages from step S10 to step S20 may be referred to as stage 1 of the recognition method of the motor system short circuit according to the present invention; step S30 is referred to as stage 2 of the method for identifying a motor system short circuit of the present invention.
It should be noted that, in the implementation process of the present embodiment, whether in the stage 1 or the stage 2, in a state where it is confirmed that the motor system has a short ground in a certain switching period, if the first switching tube in the switching period is multiple conductive, the multiple switching periods are recycled, and only the first switching tube that is not conductive is conducted in each subsequent switching period until the phase where the short ground is located is confirmed. And, said switching on of only said first switching tube which is not turned on in each subsequent switching cycle comprises: the range of the first switching tube which is not conducted is gradually reduced in each switching period.
In order to better explain the embodiments of the present embodiment, the following will specifically explain the first switching mode and the second switching mode in stages, respectively:
mode one: stage 1, lasting N11 switching cycles, and complementarily moving upper bridges and lower bridges of any i bridge arms in each switching cycle; and 2, lasting N12 switching cycles, wherein any j upper bridges and all bridge arm lower bridges in the remaining N-i upper bridges in each switching cycle are in complementary actions.
Mode two: stage 1, lasting N21 switching cycles, and complementarily actuating any i bridge arm lower bridges and all bridge arm upper bridges in each switching cycle; and 2, continuously carrying out N22 switching cycles, wherein any j lower bridges and all upper bridges in the rest N-i lower bridges in each switching cycle are in complementary actions.
Wherein N is more than or equal to 2, i is a positive integer and satisfies 1.ltoreq.i.ltoreq.n-1, j is a positive integer and satisfies 1.ltoreq.j.ltoreq.n-i, and N11, N12, N21 and N22 are positive integers respectively.
Specifically, to better illustrate the embodiment of the present solution, as shown in fig. 3, 4 switching states are performed in total in one switching cycle, where state 1 is the upper bridge switch being on, state 3 is the lower bridge switch being on, and states 2 and 4 are dead zones.
For convenience of explanation, the power system only retains the inverter 5, as shown in fig. 5 (fig. 5 is a schematic diagram of a first mode switch state) and fig. 6 (fig. 6 is a schematic diagram of a second mode switch state). Each mode is divided into two phases, each of which performs several switching cycles.
In the first mode, the 1 st, 2 nd and 3 rd bridge arms of the inverter bridge 5 are taken as examples in the stage 1, and the 8 th and 9 th bridge arms of the inverter bridge 5 are taken as examples in the stage 2, as shown in fig. 5. The phase 1 is that the state 1 is firstly kept in a switching period, and the upper bridge of the corresponding bridge arms 1, 2 and 3 is in a conducting state; secondly, keeping a state 2, wherein all bridge arms of the inverter are in a closed state; then keeping the state 3, wherein all lower bridge arms of the inverter are in a conducting state; finally, keeping the state 4, wherein all bridge arms of the inverter are in a closed state; the above phase 1 acts for N11 switching cycles. In the stage 2, the state 1 is firstly kept in a switching period, and the upper bridge of the corresponding 8 bridge arm and 9 bridge arm is in a conducting state; secondly, keeping a state 2, wherein all bridge arms of the inverter are in a closed state; then keeping the state 3, wherein all lower bridge arms of the inverter are in a conducting state; finally, keeping the state 4, wherein all bridge arms of the inverter are in a closed state; the above phase 2 acts for N12 switching cycles. The carrier frequency of each switching period is a constant value or a variable value; the duty cycle of each switching cycle is a constant value, or may be a variable value.
In the second mode, the 3 rd and 4 th legs of the inverter bridge 5 are taken as examples in the stage 1, and the 6 th leg of the inverter bridge 5 is taken as examples in the stage 2, as shown in fig. 6. The phase 1 is that the state 1 is firstly kept in a switching period, and all upper bridge arms of the inverter are in a conducting state; secondly, keeping a state 2, wherein all bridge arms of the inverter are in a closed state; then keeping the state 3, wherein the lower bridge of the corresponding 3, 4 bridge arms is in a conducting state; finally, keeping the state 4, wherein all bridge arms of the inverter are in a closed state; the above phase 1 acts for N21 switching cycles. Stage 2, firstly keeping a state 1 in a switching period, wherein all upper bridge arms of the inverter are in a conducting state; secondly, keeping a state 2, wherein all bridge arms of the inverter are in a closed state; then keeping the state 3, wherein the lower bridge of the corresponding 6 bridge arms is in a conducting state; finally, keeping the state 4, wherein all bridge arms of the inverter are in a closed state; the above phase 2 acts for N22 switching cycles. The carrier frequency of each switching period is a constant value or a variable value; the duty cycle of each switching cycle is a constant value, or may be a variable value.
When the output of the motor controller is not short or the insulation of the motor is not abnormal, through the switch function, the motor winding has no current or has small current. When the motor controller outputs short ground or the motor insulation is abnormal, larger current is generated in the motor winding through the switch function. And comparing the Hall detection current with a threshold value to identify the abnormality of the motor controller.
In a specific implementation, the winding current phase detection mode is as follows:
(1) The mode is a stage 1
When the corresponding bridge arm of the short circuit to the ground is in the 1, 2 and 3 bridge arms, the follow current cannot be formed in the winding, so that the current detection is not facilitated; when the output-to-ground short circuit corresponds to the bridge arm in the 4, 5, … …, n bridge arm, a freewheel current can be formed in the winding, so that the current in the winding can be detected.
(2) The above mode is stage 2
When the corresponding bridge arm of the short circuit to the ground is arranged in the 8 bridge arm and the 9 bridge arm, the follow current cannot be formed in the winding, so that the current detection is not facilitated;
when the output-to-ground short-circuited corresponding leg is in the legs other than 8, 9, a freewheel current can be formed in the windings, so that the current in the windings can be detected.
(3) The mode is two stage 1
When the corresponding bridge arm of the short circuit to the ground is in the 3 bridge arm and the 4 bridge arm, the follow current cannot be formed in the winding, so that the current detection is not facilitated;
when the output-to-ground short-circuit corresponding leg is in the legs other than 3, 4, a freewheel current can be formed in the winding, so that the current in the winding can be detected.
(4) Stage 2 of the above mode
When the corresponding bridge arm of the output short circuit to ground is in the 6 bridge arms, the follow current cannot be formed in the winding, so that the current detection is not facilitated;
when the output-to-ground short-circuited corresponding leg is in the leg other than 6, a freewheel current can be formed in the winding, so that the current in the winding can be detected.
Further, in order to better explain the implementation mode of the present solution, the following description uses the motor system as a three-phase motor system as an example, where an inverter of the three-phase motor system includes a U-phase bridge arm, a V-phase bridge arm, and a W-phase bridge arm; the arbitrary i bridge arms are composed of U-phase bridge arms; the embodiment is described by taking n=3 as an example, the corresponding bridge arms are UVW phases, and the U-phase upper bridge and all lower bridges, and the W-phase upper bridge and all lower bridges are complementary switching actions as examples, as shown in fig. 7. Switching frequency f s At 12kHz, duty cycle D is a constant value of 0.5, 50 switching cycles are performed per phaseThere are four states within each switching cycle. Wherein, the phase 1 state 1 is the switching-on of the upper bridge of the open U phase, the state 3 is the switching-on of the lower bridge of the UVW phase, and the states 2 and 4 are dead zones (all bridge arms are disconnected); phase 2 state 1 is the open W phase upper bridge conduction, state 3 is the UVW phase lower bridge conduction, and states 2 and 4 are dead zones (all bridge arms are open).
The stage 1 specifically comprises the following steps:
inputting the first preset pulse signals to the U-phase bridge arm, inputting the second preset pulse signals to the V-phase bridge arm and the W-phase bridge arm, and detecting the currents of motor windings corresponding to the V-phase bridge arm and the W-phase bridge arm;
and in the preset M preset pulse signals, judging that the short ground phases exist in the V-phase bridge arm and the W-phase bridge arm when the times of continuously larger than the preset current threshold value of the current values corresponding to the V-phase bridge arm and the W-phase bridge arm obtained through detection reach a preset time threshold value.
It will be appreciated that the present embodiment is described by taking the first mode as an example, and taking the U-phase upper bridge and all the lower bridges as examples in stage 1, it can be recognized that the VW corresponds to the output short ground.
The step 2 specifically comprises the following steps:
inputting the first preset pulse signals to the W-phase bridge arm, inputting the second preset pulse signals to the U-phase bridge arm and the V-phase bridge arm, and detecting the currents of motor windings corresponding to the U-phase bridge arm and the V-phase bridge arm;
in preset M preset pulse signals, judging that a phase line corresponding to the V-phase bridge arm is a short-circuit phase of the motor system when the times of detecting that the current values corresponding to the U-phase bridge arm and the V-phase bridge arm are continuously larger than the preset current threshold value reach a preset times threshold value;
it will be appreciated that the present embodiment is described by taking the first mode as an example, and taking the W-phase upper bridge and all lower bridges as examples in stage 2, the corresponding output short of UV can be identified.
Or (b)
Inputting the first preset pulse signals to the V-phase bridge arm, inputting the second preset pulse signals to the U-phase bridge arm and the W-phase bridge arm, and detecting the currents of motor windings corresponding to the U-phase bridge arm and the W-phase bridge arm;
and in the preset M preset pulse signals, judging that the phase line corresponding to the W-phase bridge arm is the short-circuit phase of the motor system when the times of continuously detecting that the obtained current values corresponding to the U-phase bridge arm and the W-phase bridge arm are larger than the preset current threshold value reach the preset times threshold value.
It will be appreciated that this embodiment is described by taking the first mode as an example, and taking the V-phase upper bridge and all lower bridges as examples in stage 2, it is possible to identify that the UW corresponds to the output short.
The beneficial effects of this embodiment lie in: inputting preset pulse signals to control ends of n bridge arms in the inverter, and conducting any one or a plurality of first switching tubes; turning off the first switching tube; turning on all the second switching tubes; turning off all the second switching tubes, thereby forming a switching cycle; and detecting the current of the motor winding in the switching period, comparing the detected current value with a preset current threshold value, and judging whether the motor system has short ground or not, so that the abnormal operation of the motor controller of the new energy automobile caused by short circuit fault can be effectively identified, the fault short place position range and the fault short place position can be determined, and the hardware cost is not increased.
As shown in fig. 8, the apparatus for identifying a short circuit of a motor system includes a processor 1001, i.e. MCU (Microcontroller Unit), which may be a motor controller in a new energy automobile or an independent MCU; a communication bus 1002 for connecting each hardware device; the motor system short circuit identification method device further comprises a memory 1003 and a computer program stored on the memory 1003 and executable on the processor 1001.
It will be appreciated by those skilled in the art that the configuration shown in fig. 8 does not constitute a limitation of the identification method apparatus of the electrical machine system short circuit, and may include more or fewer components than illustrated, or certain components may be combined, or a different arrangement of components.
As shown in fig. 8, an operating system and a computer program configured to implement the steps of the method of identifying a short circuit of the motor system may be included in a memory 1003 as a computer storage medium.
In addition, to achieve the above object, the present invention also proposes a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the method for identifying a motor system short circuit as described above.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or order of the features indicated. In the description of the present invention, unless otherwise indicated, the meaning of "plurality of" means two (two) or more than two (two).
The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the invention, but rather is intended to cover any equivalents of the structures or equivalent processes disclosed herein or in the alternative, which may be employed directly or indirectly in other related arts.
Claims (8)
1. A recognition method of short circuit of a motor system comprises an inverter, a motor, a bus positive cable, a bus negative cable, a bus positive side Y capacitor and a bus negative side Y capacitor; the inverter comprises n bridge arms, each bridge arm comprises a first switching tube and a second switching tube, the motor comprises n motor windings, the n motor windings are connected with the n bridge arms in a one-to-one correspondence manner, and n is a positive integer, and the method is characterized by comprising the following steps:
inputting preset pulse signals to control ends of n bridge arms in the inverter, and conducting any one or a plurality of first switching tubes; turning off the first switching tube; turning on all the second switching tubes; turning off all the second switching tubes to form a switching cycle,
detecting the current of a motor winding corresponding to a bridge arm except the bridge arm where the first switching tube is conducted in the switching period, and judging whether the motor system has a short ground or not according to the comparison of the detected current value and a preset current threshold value;
and when the first switching tube is not fully conducted in a state that the motor system is not short-circuited after one switching period is passed and the motor system is preliminarily judged, the conducted first switching tube is turned off in a subsequent switching period, and whether the motor system is short-circuited is judged again.
2. The method according to claim 1, wherein in a state where it is confirmed that the motor system has a short ground in a certain switching cycle, if the first switching tube in the switching cycle is a plurality of conductive, a plurality of switching cycles are circulated again, and only the first switching tube which is not conductive is conductive in each subsequent switching cycle until a phase where the short ground is located is confirmed.
3. The method of claim 2, wherein said turning on only the first switching tube that is not turned on in each subsequent switching cycle comprises: the range of the first switching tube which is not conducted is gradually reduced in each switching period.
4. The method according to claim 1, wherein the presence of a short ground phase in the motor system is determined when the number of times the detected current value continuously greater than the current threshold reaches a preset number of times threshold within a preset M preset pulse signals, the M being a positive integer greater than 1.
5. A method according to claim 3, wherein the presence of a short ground in the motor system is determined when the number of times the detected current value continuously greater than the preset current threshold reaches a preset number of times threshold within a preset number of M preset pulse signals.
6. The method according to claim 5, wherein, within a predetermined number M of the predetermined pulse signals, the motor system is determined to be pre-shorted when the detected current value is greater than the predetermined current threshold;
counting the times of occurrence of pre-short lands of the motor system under the continuous action of the preset pulse signals;
and when the occurrence number of the pre-short ground is larger than a preset number threshold, judging that the short position is positioned in the phase where the first switching tube which is not conducted is positioned.
7. An electrical machine system short circuit identification device comprising a memory and a processor, the memory having stored therein a computer program executable on the processor, the processor executing the computer program to perform the steps of the electrical machine system short circuit identification method of any one of claims 1 to 6.
8. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, implements the steps of the method for identifying a short circuit of an electrical machine system according to any one of claims 1 to 6.
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