CN112034384A - Method, device and computer-readable storage medium for identifying short circuit of motor system - Google Patents
Method, device and computer-readable storage medium for identifying short circuit of motor system Download PDFInfo
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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
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- G01R31/343—Testing dynamo-electric machines in operation
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Abstract
The invention provides a method and equipment for identifying a short circuit of a motor system and a computer readable storage medium, wherein the method is applied to the technical field of new energy automobiles; the method comprises the steps of inputting preset pulse signals to control ends of n bridge arms in the inverter and conducting any one or more first switching tubes; turning off the conducted first switch tube; all the second switch tubes are conducted; 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 a short ground or not according to the comparison between the detected current value and a preset current threshold value. The method can accurately and effectively identify the abnormal working of the motor controller of the new energy automobile caused by the short-circuit fault, can determine the position range of the fault short place, 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 a short circuit of a motor system and a computer readable storage medium.
Background
With the rapid development of new energy automobiles along with the advancement of battery and power electronic technology, the functional complexity of the automobiles is increased day by day, the regulatory requirements on safety, environmental protection and energy conservation are strict day by day, and the requirements of comfortable, flexible and personalized customers are different.
Motor controller output phases are shorted to the machine housing or motor winding insulation is abnormal, typically using changes in power to identify if the controller is abnormal. Before running, the inverter is switched on and off to make the power supply, the cable, the switch tube, the motor winding and the casing (ground) form a loop, and whether the winding has current is detected to judge whether the output is short-ground.
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 battery power supply system of a new energy automobile.
In order to meet the safety requirements of new energy vehicles and improve the electromagnetic compatibility (EMC) of the system, Y capacitors are generally connected in series between the positive electrode of the high-voltage power battery and the vehicle body and between the negative electrode of the high-voltage power battery and the vehicle body to filter out common-mode interference signals. The Y capacitor passes very little current during normal operation, and typically experiences very little nominal current to accommodate cost and volume requirements. When one phase of the AC side of the inverter has short casing or one phase winding of the motor is abnormally insulated, the motor controller forms a power loop by the battery, the bus capacitor, the switching tube and the motor, and changes the power loop into a power loop by the battery, the bus capacitor, the switching tube, the motor, the Y capacitor and the casing (ground). Therefore, oscillating current is formed in the Y capacitor, but the motor controller or the whole vehicle cannot detect the fault, and devices such as the Y capacitor, the fuse and the Hall can be burnt by large current for a long time.
The detection of the output single-phase-to-ground short circuit mainly comprises a hardware detection device and a software detection method. The typical hardware method is to connect an induction device in series with the Y capacitor branch or detect the voltage change of the Y capacitor or detect the characteristic quantity of the output side to realize fault detection. The typical software method is a method of outputting three-phase current imbalance by adopting a motor controller.
At present, the problems of the prior art are as follows:
first, the hardware detection apparatus in the prior art needs to implement detection by increasing the bandwidth or increasing the sampling frequency, and although the hardware solution has high reliability, the cost is increased by increasing the bandwidth or increasing the sampling frequency.
Secondly, in a software detection method, the existing scheme of a three-phase current imbalance method of a motor controller is a fixed threshold, the running state of the whole vehicle is not considered, the threshold setting requirement is high, the phenomena of false alarm and false alarm are easy to occur, specifically, the three-phase current imbalance is a scheme for real-time detection of the vehicle in running, but the threshold is relatively fixed and cannot adapt to the characteristic of working condition change, and the three-phase current imbalance method is easy to false alarm under some working conditions, such as a large-torque working condition, and is easy to false alarm under some working conditions, such as a low-voltage small-torque working condition.
The above is only for the purpose of assisting understanding of the technical aspects of the present invention, and does not represent an admission that the above is prior art.
Disclosure of Invention
The invention mainly aims to provide a motor system short circuit identification method, a device and a computer readable storage medium, aiming at solving the technical problem of how to effectively identify the abnormal operation of a motor controller of a new energy automobile caused by a short circuit fault.
In order to achieve the above object, the present invention provides a method for identifying a short circuit of a motor system, wherein the motor system comprises 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 mode, n is a positive integer, and the method is characterized by comprising the following steps:
inputting a preset pulse signal to the control ends of n bridge arms in the inverter, and conducting any one or more first switching tubes; turning off the conducted first switch tube; all the second switch tubes are conducted; all the second switching tubes are switched off to form a switching period,
and detecting the current of the motor winding in the switching period, and judging whether the motor system has a short ground or not according to the comparison between the detected current value and a preset current threshold value.
Preferably, after one switching period elapses and it is preliminarily determined that the motor system is not short-circuited, when the first switching tube is not fully turned on, the turned-on first switching tube is turned off in a subsequent switching period, and it is determined again whether the motor system has a short-circuited.
Preferably, in a state that the short ground of the motor system is confirmed in a certain switching period, if the first switching tube in the switching period is conducted in multiple, the switching period is cycled again for multiple times, and only the first switching tube which is not conducted in each subsequent switching period is conducted until the phase where the short ground is located is confirmed.
Preferably, said turning on only said first switch tube which is not turned on in each subsequent switch period includes: the range of the first switch tube which is not conducted is gradually reduced in each switch period.
Preferably, in preset M preset pulse signals, when the number of times that the detected current value is continuously larger than the current threshold reaches a preset number threshold, it is determined that a short earth phase exists in the motor system, where M is a positive integer larger than 1.
Preferably, in preset M preset pulse signals, when the number of times that the detected current value is continuously larger than the preset current threshold reaches a preset number threshold, it is determined that the motor system has a short ground.
Preferably, in preset M preset pulse signals, when the detected current value is greater than the preset current threshold value, it is determined that the motor system is short;
counting the times of occurrence of a preset ground of the motor system under the action of the continuous preset pulse signals;
and when the occurrence frequency of the preset short ground is greater than a preset frequency threshold value, judging that the short ground is positioned in the phase where the first switch 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 switch tube of the bridge arm to be switched on according to a first preset mode, the second switch tube of the bridge arm to be switched off according to the first preset mode, the second preset pulse signal is used for controlling the second switch tube of the bridge arm to be switched on according to a second preset mode, and the first switch tube of the bridge arm to be switched off according to the second preset mode.
In addition, in order to achieve the above object, the present invention further provides a motor system short circuit identification device, which includes a memory and a processor, wherein the memory stores a computer program operable on the processor, and the processor executes the computer program to implement the steps of the motor system abnormal operation method.
In addition, to achieve the above object, the present invention further provides a computer readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the computer program implements the steps of the method for identifying a short circuit of a motor system as described above.
The method, the equipment and the computer-readable storage medium for identifying the short circuit of the motor system have the advantages that any one or more first switching tubes are conducted by inputting preset pulse signals to the control ends of n bridge arms in the inverter; turning off the conducted first switch tube; all the second switch tubes are conducted; 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 judging whether the motor system has a short place or not according to the comparison between the detected current value and a preset current threshold value, so that the abnormal working of the motor controller of the new energy automobile caused by the short-circuit fault can be accurately and effectively identified, the position range of the fault short place can be determined, and the hardware cost is not increased.
Drawings
Fig. 1 is a schematic flow chart of a method for identifying a short circuit of a motor system according to the present invention;
fig. 2 is a schematic circuit diagram of a short circuit identification method for a motor system according to the present invention;
FIG. 3 is a schematic waveform diagram of a predetermined pulse signal according to an embodiment of the present invention;
FIG. 4a is a schematic flow chart of a method of detecting a fault in an electric machine system according to the present invention;
FIG. 4b is a logic flow diagram of a method of fault detection for an electric machine system in accordance with the present invention;
FIG. 5 is a schematic diagram of the on/off state of the first embodiment of the present invention;
FIG. 6 is a schematic diagram of the on/off state of the second embodiment 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 method and an apparatus for identifying a short circuit of a motor system according to an embodiment of the present invention.
The objects, features and advantages of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In order to solve the above technical problems, this embodiment provides a method for identifying a short circuit of a motor system, and referring to fig. 1, fig. 1 is a schematic flow diagram of a method for identifying a short circuit of a motor system in an embodiment of the present invention.
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, 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 connected with the n bridge arms in a one-to-one correspondence manner;
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 shows a structural block diagram of a new energy vehicle power system, and fig. 2 shows a structural block diagram of a new energy vehicle power system, which includes a power battery 1, a PN cable, an EMC filter unit 3, a bus support capacitor 4, an inverter bridge 5, an AC hall 6, an AC cable 7 (where 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. The PN cable is composed of a bus positive cable 21 and a bus negative cable 22. The EMC filtering unit 3 is composed of a bus positive side Y capacitor 31, a bus negative side Y capacitor 32 and a Y capacitor grounding end 33, wherein the Y capacitor is a safety capacitor. The inverter bridge 5 is composed of a motor controller shell 51, an upper bridge switch tube 52, a lower bridge switch tube 53, an output port 54 and a motor controller shell grounding end 55, wherein the upper bridge switch tube 52 and the lower bridge switch tube 53 are respectively composed of n switch tubes (n is more than or equal to 2), the upper bridge switch tube 52 is numbered from 521 to 52n in sequence, and the lower bridge switch tube 53 is numbered from 531 to 53n in sequence; the output port 54 is composed of n output terminals, and the numbers are 541 to 54n in sequence. The AC cable 7 is composed of n cables, one end of the AC cable is connected with the output port 54 of the inverter bridge 5, the other end of the AC cable is connected with the port 83 of the motor 8, and the serial numbers of the AC cable are 831 to 83n in sequence. The motor 8 consists of a motor shell 81, a winding, a motor port 83 and a motor shell grounding end 84, wherein the winding 82 is divided into n phases, and the numbers of the n phases are 821-82 n in sequence; the motor port 83 is composed of n terminals numbered 831 to 83n in this order. Y capacitor ground 33, motor controller housing 51 ground 55, and motor housing 81 ground 84 are connected to vehicle body 9, respectively.
Fig. 2 specifically shows the following connection modes: 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 supporting capacitor 4 are respectively connected with a bus positive cable 21 and a bus negative cable 22. The collectors C of the upper bridge 52 of the inverter bridge 5 are connected to the bus positive cable 21, the emitters E of the lower bridge 53 of the inverter bridge 5 are connected to the bus negative cable 22, and the emitters E of the upper bridge 52 of the inverter bridge 5 and the collectors C, AC of the lower bridge 53 of the inverter bridge 5 are connected together in a one-to-one correspondence mode. One end of the AC cable 7 is connected to the output port 54 of the inverter bridge 5, and the other end is connected to the motor port 83. The hall 6 in turn is connected across an AC cable 7.
The power battery 1 is responsible for providing electric energy and feeding back stored electric energy. The PN cable is responsible for connecting the power battery 1 and the inverter bridge 5 and is used as a path for electric energy transmission. The Y capacitors (31, 32) provide a low impedance path for system common mode interference. The bus support capacitor 4 functions to smooth the bus voltage, store energy, and provide a minimum path for the inverter bridge 5. The inverter bridge 5 is used for converting direct current into alternating current for driving the motor 8 or converting alternating current into direct current for feeding energy generated by the motor 8 back to the power battery 1. The hall 6 is used for sampling the current in the output winding and controlling the inverter bridge 5. The AC cable 7 is responsible for connecting the inverter bridge 5 and the motor 8 and provides a path for power transmission. The motor 8 realizes energy conversion and transposition, and converts electric energy into mechanical energy or converts mechanical energy into electric energy. The body 9 is used for mounting a power assembly device and plays a role in electrical connection.
Based on the circuit structure shown in fig. 2, the method for identifying a short circuit of a motor system of the present embodiment includes:
step S10: inputting a preset pulse signal to the control ends of n bridge arms in the inverter, and conducting any one or more first switching tubes; turning off the conducted first switch tube; all the second switch tubes are conducted; 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, 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 mode, the second switching tube is turned off according to the first preset mode, 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 mode, and the first switching tube is turned off according to the second preset mode.
The present embodiment can be divided into two switching modes: that is, when the first switch tube is an upper bridge switch tube, the second switch tube is a lower bridge switch tube (manner one); (mode two) when the first switch tube is a lower bridge switch tube, the second switch tube is an upper bridge switch tube;
in the specific implementation, the inverter lasts for a plurality of switching cycles, the first switching tubes of any i bridge arms and the second switching tubes of all the bridge arms perform complementary actions in each switching cycle, i is a positive integer and 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 a short ground or not according to the comparison between 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 in the embodiment:
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 as a result of the comparison, corresponding to sub-step S22 and sub-step S23:
substep S22: in preset M preset pulse signals (M is a positive integer greater than 1), when the frequency that the current value obtained by detection is continuously greater than the preset current threshold reaches a preset frequency threshold, judging that the motor system has a short earth phase; and outputs a short-ground signal;
specifically, with reference to fig. 4a and 4b (fig. 4b is a signal logic diagram taking UVW phase of a three-phase motor system as an example), within preset M preset pulse signals, when the detected current value is greater than the preset current threshold value, it is determined that the motor system is short; counting the times of occurrence of a preset ground of the motor system under the action of the continuous preset pulse signals; and when the occurrence frequency of the preset short ground is greater than a preset frequency threshold value, judging that the short ground is positioned in the phase where the first switch tube which is not conducted is positioned.
It should be noted that, referring to fig. 4b, the term "ground" herein means that ground may occur in the motor system; in a specific implementation of the present embodiment, if the number of times of occurrence of the "predetermined short zone" reaches a predetermined number of times, that is, a predetermined number of times threshold NIT; when the threshold value is exceeded, a fault of short earth is reported by accumulating NIT M times continuously, which indicates that the motor system must have a short earth phenomenon. The preset time threshold NIT (of the preset short-earth ground) of the embodiment is 10 times, and the short-earth fault is reported after 10 times of accumulation under the condition that the threshold is exceeded.
Substep 23: and outputting a signal of the motor system without short-circuit within preset M preset pulse signals when the detected current value is continuously larger than the preset current threshold value for a time not reaching a preset time threshold value.
Further, after the step of detecting the current of the motor winding, if it is determined that the short-circuit phase of the motor system does not exist according to the detected current value (i.e., the case of sub-step 23), that is, after one switching cycle elapses and in a state where it is preliminarily determined that the motor system does not have a short-circuit phase, when the first switching tube is not fully turned on, the turned-on first switching tube is turned off in a subsequent switching cycle, and it is determined again whether the short-circuit phase of the motor system exists, specifically, the following steps are performed:
step S30: lasting for a plurality of switching cycles, wherein in each switching cycle, 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 perform complementary actions; wherein j is a positive integer and satisfies that j is more than or equal to 1 and is less than n-i;
the step of performing complementary actions on 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 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 the motor windings corresponding to the j bridge arms, and judging whether the motor system has a short earth phase according to the current values obtained by detection.
It can be understood that the present embodiment may refer to the stage from step S10 to step S20 as stage 1 of the identification method for short circuit of the motor system of the present invention; step S30 is referred to as stage 2 of the method of identifying a short circuit in the motor system of the present invention.
In addition, in the implementation process of the present scheme, in either the phase 1 or the phase 2, in a state where it is determined that the short-circuit ground exists in the motor system in a certain switching period, if the first switching tube in the switching period is turned on for a plurality of times, the switching period is cycled again for a plurality of times, and only the first switching tube which is not turned on is turned on in each subsequent switching period until the phase where the short-circuit ground exists is determined. And, said conducting only said first switch tube which is not conducted in each subsequent switch cycle includes: the range of the first switch tube which is not conducted is gradually reduced in each switch period.
To better explain the embodiment of this embodiment, the first switching method and the second switching method are described in detail in stages as follows:
the first method is as follows: stage 1, lasting N11 switching cycles, and performing complementary actions of any i bridge arm upper bridges and all bridge arm lower bridges in each switching cycle; and 2, lasting for N12 switching cycles, wherein any j upper bridges in the remaining N-i upper bridges and all bridge arm lower bridges in each switching cycle perform complementary actions.
The second method comprises the following steps: stage 1, lasting N21 switching cycles, and performing complementary actions of any i lower bridges and all upper bridges of the bridge arms in each switching cycle; and 2, lasting for N22 switching cycles, wherein any j lower bridges in the remaining N-i lower bridges and all bridge arms upper bridges in each switching cycle perform complementary actions.
Wherein N is more than or equal to 2, i is a positive integer and satisfies that i is more than or equal to 1 and less than or equal to N-1, j is a positive integer and satisfies that j is more than or equal to 1 and less than N-i, and N11, N12, N21 and N22 are positive integers respectively.
Specifically, to better explain the implementation of the present scheme, as shown in fig. 3, 4 switching states are performed in a switching cycle, where state 1 is the upper bridge switch conducting, state 3 is the lower bridge switch conducting, and states 2 and 4 are dead zones.
For convenience of description, the power system only includes the inverter 5, as shown in fig. 5 (fig. 5 is a schematic diagram of the switching state of the first embodiment) and fig. 6 (fig. 6 is a schematic diagram of the switching state of the second embodiment). Each mode is divided into two phases, each of which performs a number of switching cycles.
In the first mode, the stage 1 takes the 1 st, 2 nd and 3 rd bridge arms in the inverter bridge 5 as an example, and the stage 2 takes the 8 th and 9 th bridge arms in the inverter bridge 5 as an example, as shown in fig. 5. The stage 1 firstly keeps a state 1 in a switching period, and corresponding bridge arms 1, 2 and 3 are in a conducting state; secondly, keeping the state 2, and enabling all bridge arms of the inverter to be in a closed state; then keeping the state 3, and enabling all lower bridge arms of the inverter to be in a conducting state; finally, keeping the state 4, wherein all bridge arms of the inverter are in a closed state; the phase 1 above applies N11 switching cycles. Stage 2, firstly keeping the state 1 in one switching period, and correspondingly keeping the bridge on the bridge arms of 8 and 9 in a conducting state; secondly, keeping the state 2, and enabling all bridge arms of the inverter to be in a closed state; then keeping the state 3, and enabling all lower bridge arms of the inverter to be in a conducting state; finally, keeping the state 4, wherein all bridge arms of the inverter are in a closed state; phase 2 above applies N12 switching cycles. The carrier frequency of each switching period is a constant value and can also be a variable value; the duty cycle of each switching cycle is a constant value, and may also be a variable value.
In the second mode, the 3 rd and 4 th bridge arms in the inverter bridge 5 are taken as an example in the stage 1, and the 6 th bridge arm in the inverter bridge 5 is taken as an example in the stage 2, as shown in fig. 6. Stage 1, firstly, keeping a state 1 in a switching period, and enabling all upper bridge arms of the inverter to be in a conducting state; secondly, keeping the state 2, and enabling all bridge arms of the inverter to be in a closed state; then keeping the state 3, and correspondingly keeping the lower bridge of the 3 and 4 bridge arms in a conducting state; finally, keeping the state 4, wherein all bridge arms of the inverter are in a closed state; the phase 1 above applies N21 switching cycles. Stage 2, firstly keeping the state 1 in one switching period, and enabling all upper bridge arms of the inverter to be in a conducting state; secondly, keeping the state 2, and enabling all bridge arms of the inverter to be in a closed state; then keeping the state 3, and correspondingly keeping the bridge arm lower bridge of 6 in a conducting state; finally, keeping the state 4, wherein all bridge arms of the inverter are in a closed state; phase 2 above applies N22 switching cycles. The carrier frequency of each switching period is a constant value and can also be a variable value; the duty cycle of each switching cycle is a constant value, and may also be a variable value.
When the output of the motor controller is not short or the motor insulation is not abnormal, the motor winding has no current or little current through the switching action. When the output of the motor controller is short or the motor insulation is abnormal, a larger current is generated in the motor winding through the switching action. And identifying the abnormality of the motor controller by comparing the Hall detection current with a threshold value.
In a specific implementation, the winding current phase detection mode is as follows:
(1) mode one stage 1
When the output short circuit to ground corresponds to the bridge arm 1, 2 and 3, the winding can not form follow current, thus being not beneficial to current detection; when the output-to-ground short-circuit corresponding arm is the 4, 5, … …, n arm, a free-wheeling current can be formed in the winding, and thus the current in the winding can be detected.
(2) Mode one stage 2
When the output short circuit corresponding bridge arm to the ground is in 8 and 9 bridge arms, no follow current can be formed in the winding, so that the current detection is not facilitated;
when the output is shorted to ground in the corresponding arm except 8, 9, a freewheeling current can be formed in the winding, and thus the current in the winding can be detected.
(3) Two stages 1 of the above-described mode
When the output short-circuit corresponding bridge arm to the ground is in the 3 and 4 bridge arms, the follow current cannot be formed in the winding, so that the current detection is not facilitated;
when the output is shorted to ground in the corresponding arm except 3, 4, a freewheel current can be formed in the winding, and thus the current in the winding can be detected.
(4) Two stages 2 of the above method
When the output short circuit corresponding bridge arm to the ground is in the 6 bridge arm, no follow current can be formed in the winding, so that the current detection is not facilitated;
when the output short-circuits the corresponding leg to ground in the legs other than 6, a freewheel current can be formed in the winding, and thus the current in the winding can be detected.
Further, to better explain the embodiments of the present solution, the following description will be made ofThe motor system is explained by taking a three-phase motor system as an example, and an inverter of the three-phase motor system comprises a U-phase bridge arm, a V-phase bridge arm and a W-phase bridge arm; the arbitrary i bridge arms consist of U-phase bridge arms; the embodiment will be described by taking n as an example and 3, and the UVW phase is used for each arm, and the U-phase upper bridge and all lower bridges, and the W-phase upper bridge and all lower bridges complement switching actions are taken as examples, as shown in fig. 7. Switching frequency fsAt 12kHz, the duty cycle D is a constant value of 0.5, each stage performs 50 switching cycles with four states in each switching cycle. In the stage 1, a state 1 is that a U-phase upper bridge is opened and conducted, a state 3 is that a UVW-phase lower bridge is conducted, and a state 2 and a state 4 are dead zones (all bridge arms are disconnected); in the stage 2, the state 1 is that the upper bridge of the W phase is opened and conducted, the state 3 is that the lower bridge of the UVW phase is conducted, and the states 2 and 4 are dead zones (all bridge arms are disconnected).
inputting the first preset pulse signal to the U-phase bridge arm, inputting the second preset pulse signal to the V-phase bridge arm and the W-phase bridge arm, and detecting the current of the motor windings corresponding to the V-phase bridge arm and the W-phase bridge arm;
and in M preset pulse signals, when the number of times that the detected current values corresponding to the V-phase bridge arm and the W-phase bridge arm are continuously larger than the preset current threshold reaches a preset number threshold, judging that the V-phase bridge arm and the W-phase bridge arm have a short earth phase.
It is understood that the embodiment is described by way of example, and phase 1 is exemplified by U-phase upper bridge and all lower bridges, so that it can be recognized that VW corresponds to the output ground.
inputting the first preset pulse signal to the W-phase bridge arm, inputting the second preset pulse signal to the U-phase bridge arm and the V-phase bridge arm, and detecting the current of the motor windings corresponding to the U-phase bridge arm and the V-phase bridge arm;
in M preset pulse signals, when the number of times that the detected current values corresponding to the U-phase bridge arm and the V-phase bridge arm are continuously larger than the preset current threshold reaches a preset number threshold, determining that the phase line corresponding to the V-phase bridge arm is the short earth phase of the motor system;
it is understood that the embodiment is described by way of example, and phase 2 is exemplified by W-phase upper bridge and all lower bridges, and it can be recognized that UV corresponds to the output ground.
Or
Inputting the first preset pulse signal to the V-phase bridge arm, inputting the second preset pulse signal to the U-phase bridge arm and the W-phase bridge arm, and detecting the current of the motor windings corresponding to the U-phase bridge arm and the W-phase bridge arm;
and in M preset pulse signals, when the number of times that the detected current values corresponding to the U-phase bridge arm and the W-phase bridge arm are continuously larger than the preset current threshold reaches a preset number threshold, determining that the phase line corresponding to the W-phase bridge arm is the short-ground phase of the motor system.
It is understood that the embodiment is described by taking the first mode as an example, and the phase 2 takes the V-phase upper bridge and all lower bridges as examples, so that the corresponding output ground of UW can be identified.
The beneficial effect of this embodiment lies in: inputting a preset pulse signal to the control ends of n bridge arms in the inverter, and conducting any one or more first switching tubes; turning off the conducted first switch tube; all the second switch tubes are conducted; turning off all the second switching tubes, thus forming a switching period; and 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 a short place or not, so that the working abnormity 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 required to be increased.
As shown in fig. 8, the device for identifying a short circuit of a motor system includes a processor 1001, namely, an MCU (microcontroller unit), where the processor may be a motor controller inside a new energy vehicle, or may be an independent MCU; a communication bus 1002 for connecting each hardware device; the motor system short circuit identification method further includes a memory 1003, and a computer program stored in 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 method of identification of a short circuit of the motor system and may comprise more or less components than those shown, or some components may be combined, or a different arrangement of components.
As shown in fig. 8, the memory 1003, which is a kind of computer storage medium, may include therein an operating system and a computer program configured to implement the steps of the method for identifying a short circuit of the motor system.
In addition, to achieve the above object, the present invention further provides a computer readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the computer program implements the steps of the method for identifying a short circuit of a motor system 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 an … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element.
Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number, or order, of the technical features indicated. In the description of the present invention, the meaning of "plurality" means two (two pieces) or two or more (two pieces) unless otherwise specified.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A method for identifying a short circuit of a motor system, wherein the motor system comprises 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 mode, n is a positive integer, and the method is characterized by comprising the following steps:
inputting a preset pulse signal to the control ends of n bridge arms in the inverter, and conducting any one or more first switching tubes; turning off the conducted first switch tube; all the second switch tubes are conducted; all the second switching tubes are switched off to form a switching period,
and detecting the current of the motor winding in the switching period, and judging whether the motor system has a short ground or not according to the comparison between the detected current value and a preset current threshold value.
2. The method according to claim 1, wherein after one switching period is passed and in a state where the motor system is preliminarily judged not to have a short ground, when the first switching tube is not fully turned on, the turned-on first switching tube is turned off in a subsequent switching period, and whether the motor system has a short ground is judged again.
3. The method according to claim 1 or 2, characterized in that in a state that the short earth of the motor system is confirmed in a certain switching period, if the first switching tube in the switching period is conducted in multiple times, the switching period is cycled again for multiple times, and only the first switching tube which is not conducted in each subsequent switching period is conducted until the phase where the short earth is located is confirmed.
4. The method of claim 3, wherein turning on only the first switch tube that is not turned on in each subsequent switching cycle comprises: the range of the first switch tube which is not conducted is gradually reduced in each switch period.
5. The method according to claim 1, characterized in that the existence of a short earth phase in the motor system is determined when the number of times that the detected current value is continuously larger than the current threshold value reaches a preset number threshold value within preset M preset pulse signals, wherein M is a positive integer larger than 1.
6. The method according to claim 4, characterized in that, in a preset number M of the preset pulse signals, when the number of times that the detected current value is continuously larger than the preset current threshold value reaches a preset number threshold value, it is determined that the motor system has a short ground.
7. The method according to claim 6, characterized in that, within a preset number M of the preset pulse signals, when the detected current value is greater than the preset current threshold value, the motor system is determined to be short;
counting the times of occurrence of a preset ground of the motor system under the action of the continuous preset pulse signals;
and when the occurrence frequency of the preset short ground is greater than a preset frequency threshold value, judging that the short ground is positioned in the phase where the first switch tube which is not conducted is positioned.
8. The method according to claim 1, wherein the preset pulse signals include a first preset pulse signal and a second preset pulse signal, the first preset pulse signal is used for controlling a first switch tube of the bridge arm to be turned on according to a first preset mode, a second switch tube of the bridge arm to be turned off according to the first preset mode, the second preset pulse signal is used for controlling a second switch tube of the bridge arm to be turned on according to a second preset mode, and the first switch tube of the bridge arm to be turned off according to the second preset mode.
9. An electric machine system short circuit identification device, characterized by comprising a memory and a processor, wherein the memory stores a computer program operable on the processor, and the processor executes the computer program to implement the steps of the electric machine system operation abnormality method according to any one of claims 1 to 8.
10. A computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, which computer program, when being executed by a processor, carries out the steps of the method for identifying a short circuit of an electric machine system according to any one of claims 1 to 8.
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