CN110808574B - Protection method and protection system of filter capacitor and motor controller - Google Patents
Protection method and protection system of filter capacitor and motor controller Download PDFInfo
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- CN110808574B CN110808574B CN201910950669.XA CN201910950669A CN110808574B CN 110808574 B CN110808574 B CN 110808574B CN 201910950669 A CN201910950669 A CN 201910950669A CN 110808574 B CN110808574 B CN 110808574B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/16—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for capacitors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
- H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
- H02H7/0856—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load characterised by the protection measure taken
- H02H7/0858—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load characterised by the protection measure taken by reversing, cycling or reducing the power supply to the motor
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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
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/64—Electric machine technologies in electromobility
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Abstract
The invention provides a protection method and a protection system of a filter capacitor and a motor controller. According to the invention, the filter capacitor is protected by a physical modeling method, and the transfer of the maximum absolute temperature value caused by working condition change when the temperature sensor collects the temperature of the filter capacitor is avoided. Meanwhile, compared with the traditional temperature sensor measurement, the physical modeling has stronger robustness and consistency, and can effectively avoid the inaccuracy of temperature measurement data caused by inconsistent characteristics or aging of the service life of the temperature sensor. In addition, the protection method of the filter capacitor provided by the invention can replace a temperature sensor, so that the production cost is reduced.
Description
Technical Field
The invention relates to the technical field of electric vehicle control, in particular to a protection method and a protection system of a filter capacitor and a motor controller.
Background
Electric automobiles are widely considered as one of the main approaches to solve the problems of automobile exhaust pollution, petroleum energy shortage and the like, and along with the rapid development of electric automobiles, the requirements on the product performance, consistency and reliability of core parts of the electric automobiles are more and more important. The motor controller is used as a control unit of the power assembly of the electric automobile, and the performance of the product of the motor controller directly influences the performance index of the whole automobile. The current output capability of the motor controller is influenced by various factors, and from the viewpoint of the control machine, the heating of the components is a factor for mainly limiting the current capability output. Because components generate heat to different degrees during operation, the temperature rise of the components must be strictly limited in order to avoid thermal damage of the components and meet the service life of the controller, and therefore when the temperature reaches the upper limit value of a design index, the output capacity of the controller needs to be reduced.
The filter capacitor in the motor controller acts as a filter buffer for the dc side and also directly limits the continuous output capability of the motor controller. When the filter capacitor needs protection because of too high temperature, the continuous output current of the motor controller needs to be reduced to prevent irreversible thermal damage of the filter capacitor. It is therefore important to protect the filter capacitor from overheating.
The common protection mode is that a temperature sensor is placed at a heating point of a component, and the controller is used for collecting temperature signals to realize the protection of the controller. However, there are two important disadvantages to this approach: firstly, the product cost can be directly increased by adding a physical temperature sensor, and the price of a common thermocouple is about 20-30 RMB; secondly, under the conditions that the capacitor is large in size, complex in structural material and variable in working environment, the highest temperature point in the filter capacitor is always changed continuously, and the highest temperature point cannot be accurately measured by a temperature sensor at a fixed position, so that the protection effect cannot be achieved.
Disclosure of Invention
The invention aims to provide a filter capacitor protection method, a filter capacitor protection system and a motor controller.
Another objective of the present invention is to provide a protection method, a protection system and a motor controller for a wave capacitor, which replace a temperature sensor to obtain the absolute temperature of a filter capacitor, so as to reduce the production cost and avoid the inaccuracy of temperature measurement data caused by the inconsistency of the characteristics of the temperature sensor or the aging of the lifetime of the temperature sensor.
In order to achieve the above object, the present invention provides a protection method for a filter capacitor, which is used for performing overheat protection on the filter capacitor in a motor controller, and comprises:
collecting data information of the filter capacitor under various working conditions;
carrying out physical modeling on the data information, and forming a physical model corresponding to the working condition to obtain the absolute temperature of the filter capacitor;
setting a temperature protection threshold value of the filter capacitor corresponding to the working condition;
acquiring input information under a certain working condition, and inputting a physical model corresponding to the working condition for acquiring the absolute temperature of the filter capacitor; and the number of the first and second groups,
and judging the magnitude relation between the absolute temperature of the filter capacitor and the temperature protection threshold value under the working condition, and controlling the output information of the motor controller according to the judgment result.
Optionally, the data information and the input information both include: the ripple current of the filter capacitor, the direct current on the direct current side and the water cooling temperature.
Optionally, the process of obtaining the absolute temperature of the filter capacitor includes:
acquiring ripple current of a filter capacitor and direct current of a direct current side under a certain working condition, and inputting a physical model corresponding to the working condition to acquire an absolute temperature rise value of the filter capacitor;
and acquiring the water cooling temperature, and calculating the absolute temperature of the filter capacitor according to the water cooling temperature and the absolute temperature rise value.
Optionally, the water cooling temperature is obtained by a water temperature sensor in the water cooling system.
Optionally, the output information includes: output power of the motor controller.
Optionally, when the absolute temperature of the filter capacitor is lower than the temperature protection threshold, the output power of the motor controller is not limited; when the absolute temperature of the filter capacitor exceeds the temperature protection threshold, the motor controller correspondingly reduces the actual output power on the basis of the rated output power.
Optionally, the temperature protection threshold includes a temperature protection threshold upper limit and a temperature protection threshold lower limit, when the absolute temperature of the filter capacitor exceeds the temperature protection threshold lower limit and does not reach the temperature protection threshold upper limit, the output power of the motor controller is linearly reduced, and when the absolute temperature of the filter capacitor reaches the temperature protection threshold upper limit, the output power of the motor controller is limited to 0.
Optionally, the filter capacitor is a thin film capacitor.
Optionally, the filter capacitor is a polypropylene film capacitor.
Based on the same inventive concept, the invention also provides a protection system of the filter capacitor, which is used for dynamically acquiring the absolute temperature of the filter capacitor in the motor controller in real time and protecting the absolute temperature, and comprises the following steps: an input module, an analysis module, a threshold setting module and an output module,
the input module is used for acquiring input information under a certain working condition and transmitting the input information to the analysis module;
the analysis module analyzes according to the input information to obtain the absolute temperature of the filter capacitor;
the threshold setting module is used for setting a temperature protection threshold corresponding to the working condition;
the output module judges the magnitude relation between the absolute temperature and the temperature protection threshold value and controls the output information of the motor controller according to the judgment result.
Optionally, the analysis module includes physical models corresponding to different working conditions of the filter capacitor, and the physical models are formed by performing physical modeling in a manner of combining specific input information and calibration results.
Optionally, the input information includes: the ripple current of the filter capacitor, the direct current on the direct current side and the water cooling temperature.
Optionally, the process of obtaining the absolute temperature of the filter capacitor includes:
the method comprises the following steps that an input module obtains ripple current of a filter capacitor, direct current on a direct current side and water cooling temperature under a certain working condition, and inputs the ripple current of the filter capacitor, the direct current on the direct current side and the water cooling temperature to an analysis module;
and the analysis module inputs the ripple current of the filter capacitor and the direct current of the direct current side into a physical model corresponding to the working condition so as to obtain an absolute temperature rise value of the filter capacitor, and the absolute temperature of the filter capacitor is calculated according to the water cooling temperature and the absolute temperature rise value.
Optionally, the water cooling temperature is obtained by a water temperature sensor in the electric water cooling system.
Optionally, the output information includes: output power of the motor controller.
Optionally, when the absolute temperature of the filter capacitor is lower than the temperature protection threshold, the output module does not limit the output power of the motor controller; when the absolute temperature of the filter capacitor exceeds the temperature protection threshold, the output module correspondingly reduces the actual output power on the basis of the rated output power of the motor controller.
Optionally, the temperature protection threshold includes a temperature protection threshold upper limit and a temperature protection threshold lower limit, and when the absolute temperature of the filter capacitor exceeds the temperature protection threshold lower limit and does not reach the temperature protection threshold upper limit, the output power of the output module control motor controller is linearly reduced, and when the absolute temperature of the filter capacitor reaches the temperature protection threshold upper limit, the output power of the output module limit motor controller is 0.
Optionally, the filter capacitor is a thin film capacitor.
Optionally, the filter capacitor is a polypropylene film capacitor.
Based on the same inventive concept, the invention also provides a motor controller, comprising: a filter capacitor protection system for dynamically acquiring and protecting an absolute temperature of a filter capacitor in real time, comprising: the device comprises an input module, an analysis module, a threshold setting module and an output module, wherein the input module is used for acquiring input information under a certain working condition and transmitting the input information to the analysis module; the analysis module analyzes according to the input information to obtain the absolute temperature of the filter capacitor; the threshold setting module is used for setting a temperature protection threshold corresponding to the working condition; the output module judges the magnitude relation between the absolute temperature and the temperature protection threshold value and controls the output information of the motor controller according to the judgment result.
In summary, the protection method for the filter capacitor provided by the invention dynamically obtains the absolute temperature of the filter capacitor in real time through a physical modeling method, and controls the output capability of the motor controller according to the relationship between the obtained absolute temperature value of the filter capacitor and the set temperature protection threshold, so as to perform thermal protection on the filter capacitor. According to the invention, the filter capacitor is protected by a physical modeling method, so that the influence of absolute temperature maximum value transfer of the filter capacitor caused by working condition change is avoided.
Meanwhile, compared with the absolute temperature of the filter capacitor obtained by the traditional temperature sensor, the physical modeling has stronger robustness and consistency, and the inaccuracy of temperature measurement data caused by the inconsistency of the characteristics of the temperature sensor or the aging of the service life of the temperature sensor can be effectively avoided. In addition, the protection method of the filter capacitor provided by the invention can effectively replace a temperature sensor, and the production cost is reduced.
Drawings
FIG. 1 is a flow chart of a filter capacitor protection method according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a filter capacitor according to an embodiment of the present invention;
FIG. 3 is a circuit design of a filter capacitor in a motor controller according to an embodiment of the present invention;
FIG. 4 is a block diagram of a filter capacitor absolute temperature acquisition process in an embodiment of the present invention;
FIG. 5 is a block diagram of the power output of a filter capacitor in an embodiment of the invention;
FIG. 6 is a block diagram of a filter capacitor protection system in an embodiment of the invention;
FIG. 7 is a graph of absolute temperature rise of a filter capacitor versus actual measured value over time in accordance with an embodiment of the present invention;
FIG. 8 is a graph of the error between the absolute temperature rise of the filter capacitor and the actual measured value over time for an embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings in order to make the objects and features of the present invention more comprehensible, however, the present invention may be realized in various forms and should not be limited to the embodiments described above. Furthermore, it will be understood that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer program instructions. It is well known to those skilled in the art that implementation by hardware, by software, and by a combination of software and hardware are equivalent.
Referring to fig. 1, the present invention provides a protection method of a filter capacitor for performing overheat protection of the filter capacitor in a motor controller, including the following steps:
s01: collecting data information of the filter capacitor under various working conditions;
s02: carrying out physical modeling on the data information to form a physical model corresponding to the working condition for obtaining the absolute temperature of the filter capacitor;
s03: setting a temperature protection threshold value of the filter capacitor corresponding to the working condition;
s04: acquiring input information under a certain working condition and inputting a physical model corresponding to the working condition to acquire the absolute temperature of the filter capacitor;
s05: and judging the magnitude relation between the absolute temperature of the filter capacitor and the corresponding temperature protection threshold value, and controlling the output information of the motor controller according to the judgment result.
The protection method of the filter capacitor provided by the invention is described below by taking the filter capacitor in the motor controller as an example, wherein the filter capacitor is a thin film capacitor. As shown in fig. 2, the basic structure of the filter capacitor includes: the capacitor comprises a shell (not shown in the figure), a positive copper bar 11, a negative copper bar 12, insulating paper 13 and a capacitor core 10, wherein one end of the capacitor core 10 is connected with the positive copper bar 11, the other end of the capacitor core is connected with the negative copper bar 12, the insulating paper 13 is arranged between the two layers of copper bars, and the capacitor core 10, the positive copper bar 11, the insulating paper 13 and the negative copper bar 12 are wrapped by the shell; and pins 14 are arranged on the two layers of copper bars and extend to the outside of the shell. It can be seen that, the inside multiple material substance that contains of filter capacitor, the heat conduction electric conduction characteristic of different materials is all different, and filter capacitor is bulky, is the square shape in certain space, and the inside hot spot of filter capacitor can change along with the change of operating mode under the operating condition.
The principle of the internal heating of the filter capacitor is that alternating current flows through the capacitor under the working state, different materials have different impedance characteristics, power loss is generated after the current flows through the capacitor, and heat is generated when the current acts on thermal resistance. The basic thermal principle is shown in formula (1), where Δ T is the temperature rise of a filter capacitor at a certain node, P is the power loss, and R is c Is the thermal resistance of the corresponding node. Therefore, the equivalent current flowing through the filter capacitor body is calculated and can be used for representing the power loss condition of the filter capacitor.
ΔT＝P·R c (1)
Fig. 3 is a schematic circuit diagram of a filter Capacitor in a motor controller, which can visually see the relationship between the DC-side equivalent Current of the DC-side Capacitor (DC Cap), the DC-side Current of the line inlet and the input Current of the inverter cap The calculation formula of (2):
wherein, I inv_rms Is the ripple current; i is pha Is the phase current; m is a modulation degree;
is a power factor.
Because the internal material and the shape of the filter capacitor are complex, accurate impedance parameters are difficult to obtain, and meanwhile, only ripple current flows inside the filter capacitor when the filter capacitor works, and the flow path of equivalent ripple current is clear, so that the ripple current of the filter capacitor is directly used as equivalent input of loss.
Referring to fig. 3, it can be seen that the connection position of the filter capacitor on the hardware circuit is directly connected to the dc side, and since the filter capacitor structure includes conductive copper bars at two ends, the current on the dc side flows through the copper bars, and further generates a certain amount of heat. The heat generated on the copper bar can directly influence the heat effect of the internal material of the capacitor. Therefore, the magnitude of the current on the dc side also affects the capacitor heat transfer to some extent, and should be used as input information.
After the structure of the filter capacitor is fixed, the thermal resistance parameter as the inherent characteristic parameter will not be changed, and the thermal characteristic can be regarded as the specific performance under a certain working condition input. Therefore, on the basis of basic analysis and equivalence, the capacitor is protected by adopting a physical modeling method, the core is to observe the hottest point of a capacitor core in the filter capacitor under the current working condition, and then the power output is limited by utilizing a temperature protection threshold value, so that the protection of the capacitor is realized.
Firstly, data information of the filter capacitor under various working conditions is collected. The data information includes the above mentioned nanofabric current of the filter capacitor and the dc current of the dc side, and certainly includes the types of the filter capacitors corresponding to different working conditions, the specific connection mode of the filter capacitors on the hardware circuit, the settings of other operation parameters, and the like. And then, carrying out physical modeling on the data information to form a physical model corresponding to the working condition so as to obtain the absolute temperature of the filter capacitor under the working condition. In the embodiment, a mode of combining specific data information and a calibration result is adopted to complete mathematical observation of absolute temperature and temperature of the filter capacitor, then physical models corresponding to different working conditions are constructed according to the mathematical observation result, a basic structure block diagram of the physical models is shown in FIG. 4, I cap For filtering capacitor ripple current, I dc The direct current on the direct current side is direct current,ΔT cap the method includes the steps that the absolute temperature rise value of a filter capacitor is obtained, wherein the ripple current of the filter capacitor and the direct-current side direct current of the filter capacitor are key data information for constructing a physical model, data information is collected through thermal calibration of a single sample, then physical modeling is carried out on collected data, corresponding to the corresponding physical model under the same working condition of the same product, and when input information (the ripple current I of the filter capacitor) is input into the corresponding physical model cap And DC side DC I dc ) And outputting the absolute temperature rise value delta T of the filter capacitor under the working condition through the operation of a physical model cap 。
Obtaining the absolute temperature rise value Delta T of the filter capacitor under a certain working condition cap Then, the absolute temperature rise value Δ T cap The temperature change value of a certain node of the filter capacitor under the working condition is dynamically changed, and therefore, the delta T is obtained cap Then, the absolute temperature rise value Delta T is also required to be measured through a low-pass filter cap Performing corresponding modulation and smoothing delta T cap And suppressing interfering signals so that the absolute temperature rise value Δ T cap The dynamic rising trend is stable, and the low-pass filter can be a first-order low-pass filter (PT1) for example.
The absolute temperature rise value delta T of the filter capacitor under a certain working condition can be obtained cap However, the greater the reference meaning for the filter capacitor temperature protection is the filter capacitor temperature absolute temperature T f Therefore, the temperature T of water cooling in filter capacitor application also needs to be considered 0 . The block diagram of the scheme structure is shown in fig. 5. As shown in fig. 2, the water cooling facility 15 is generally disposed below the copper bars of the smoothing capacitor, wherein the water cooling temperature T 0 The acquisition of the temperature of the water cooling system can be obtained through a motor controller or a water temperature sensor in the water cooling system of the whole vehicle, or can also be obtained through an estimation system of the temperature of the water cooling system by the motor controller. Obtaining the Water-Cooling temperature T 0 Then according to the water-cooling temperature T 0 And the absolute temperature rise value Delta T cap Calculating the absolute temperature T of the filter capacitor f 。
Then, set upTemperature protection threshold T of filter capacitor corresponding to corresponding working condition p . When the absolute temperature T of the filter capacitor f Does not reach the set temperature protection threshold value T p When the absolute temperature T of the filter capacitor is not limited, the output information of the motor controller is not limited f Reach the set temperature protection threshold value T p When the absolute temperature T of the filter capacitor is lower than the reference value, the output information of the motor controller is correspondingly limited, for example, the actual output power is correspondingly reduced on the basis of the original rated output power, and further, when the absolute temperature T of the filter capacitor is lower than the reference value f Exceeding a set temperature protection threshold T p Within a certain range, the output information of the motor controller correspondingly reduces the actual output power according to the exceeding temperature, for example, the actual output power can be increased with the exceeding T p Increase of (a) linearly decreases when T is exceeded p When the temperature of the motor reaches a certain node, the output limit of the motor controller is 0, so that the purpose of overheat protection of the filter capacitor is achieved.
The physical model corresponding to the working condition is established and the temperature protection threshold value T is set p When the input information under a certain working condition is obtained, the physical model corresponding to the working condition is input to obtain the absolute temperature T of the filter capacitor f 。
Then, the absolute temperature T of the filter capacitor is judged f With corresponding temperature protection threshold T p The magnitude relationship between them; and finally, controlling the output information of the motor controller according to the judgment result. The output information includes output current, output voltage, and the like, and preferably, the output power of the motor controller is used in this embodiment. When the absolute temperature T of the filter capacitor f Below the temperature protection threshold T p When the motor is started, the output power of the motor controller is not limited; when the absolute temperature T of the filter capacitor f Exceeding the temperature protection threshold T p And meanwhile, the motor controller correspondingly reduces the actual output power on the basis of the original output power.
Illustratively, the temperature protection threshold T p Including an upper temperature protection threshold T p1 And lower temperature protection threshold T p2 When the absolute temperature T of the filter capacitor f Exceeding the lower temperature protection threshold T p2 And does not reach the upper limit T of the temperature protection threshold value p1 When the absolute temperature T of the filter capacitor is lower than the reference temperature T, the output power of the motor controller is linearly reduced f Reaching the upper temperature protection threshold T p1 The output power of the motor controller is limited to 0.
FIG. 7 is a diagram illustrating an absolute temperature rise value Δ T of the filter capacitor obtained in the present embodiment cap Fig. 8 is a relationship between an error between an absolute temperature rise value of the filter capacitor obtained in the present embodiment and an actual measurement value and time. Referring to fig. 7 and 8, it can be seen; under a certain working condition, the absolute temperature rise value delta T of the filter capacitor obtained by the embodiment 1 And the actual measured value DeltaT 2 The high consistency is kept, and in the whole dynamic process, the absolute temperature rise value Delta T of the filter capacitor acquired by the embodiment 1 And the actual measured value DeltaT 2 The error of the filter capacitor protection method is basically within 2 ℃, and the high estimation precision is achieved, so that the effectiveness of the filter capacitor protection method provided by the embodiment is proved.
In the protection method for the filter capacitor provided in this embodiment, the filter capacitor is a polypropylene film capacitor, and the application environment and the product are mainly based on a motor controller, but the protection method is also applicable to other types of capacitors, and meanwhile, not only is the product limited to the motor controller, but also the filter capacitor used on the dc side in an inverter system can be protected and designed by using a similar scheme.
Referring to fig. 6, based on the same inventive concept, an embodiment of the present invention further provides a protection system 100 for a filter capacitor, for dynamically obtaining an absolute temperature of the filter capacitor in a motor controller in real time and protecting the absolute temperature, including: an input module 101, an analysis module 102, a threshold setting module 103 and an output module 104,
the input module 101 is used for acquiring input information under a certain working condition and transmitting the input information to the analysis module;
the analysis module 102 is based onThe input information is analyzed to obtain the absolute temperature T of the filter capacitor f ；
The threshold setting module 103 is used for setting a temperature protection threshold T corresponding to a working condition p ；
The output module 104 determines the absolute temperature T f And the temperature protection threshold T p And controlling the output information of the motor controller according to the judgment result.
Specifically, the analysis module 102 includes physical models corresponding to different working conditions of the filter capacitor, and the physical models are formed by performing physical modeling in a manner of combining specific input data information and calibration results. The input information comprises ripple current Icap of a filter capacitor and direct current I at a direct current side dc And water cooling temperature T 0 The method also includes the types of the filter capacitors corresponding to different working conditions, the specific connection mode of the filter capacitors on the hardware circuit, the setting of other operation parameters, and the like. Wherein the absolute temperature T of the filter capacitor is obtained f The process of (2) comprises:
the input module 101 obtains the ripple current I of the filter capacitor under a certain condition cap Direct current I at the direct current side dc And water cooling temperature T 0 And the ripple current I of the filter capacitor is measured cap Direct current I at the direct current side dc And water cooling temperature T 0 Input to the analysis module 102.
The analysis module 102 converts the ripple current I cap A direct current I on the direct side dc Inputting a physical model corresponding to the working condition to obtain an absolute temperature rise value delta T of the filter capacitor cap And according to the water-cooling temperature T 0 And the absolute temperature rise value Delta T cap Calculating the absolute temperature T of the filter capacitor f 。
In addition, when Δ T is acquired cap Then, the absolute temperature rise value delta T is also required to be measured through a low-pass filter cap Performing corresponding modulation and smoothing delta T cap And suppressing interfering signals so that the absolute temperature rise value Δ T cap Is in a comparisonA stable dynamic trend, said low pass filter may for example be a first order low pass filter (PT 1).
The threshold setting module 103 may be set according to specific operating conditions, and the operating conditions may be directly obtained through the input module 101 or indirectly obtained from the analysis module 102.
The output module 104 is used for outputting the absolute temperature T f And the temperature protection threshold T p The magnitude relation between the output current and the output voltage controls the output information of the motor controller, and the output information comprises the output current, the output voltage and the like. When the absolute temperature T of the filter capacitor f Below the temperature protection threshold T p When the motor is started, the output power of the motor controller is not limited; when the absolute temperature T of the filter capacitor f Exceeding the temperature protection threshold T p In the process, the motor controller correspondingly reduces the actual output power on the basis of the original output power. Illustratively, the temperature protection threshold T p Including an upper temperature protection threshold T p1 And lower temperature protection threshold T p2 When the absolute temperature T of the filter capacitor f Exceeds the lower temperature protection threshold T p2 And does not reach the upper limit T of the temperature protection threshold value p1 When the absolute temperature T of the filter capacitor is lower than the reference temperature T, the output power of the motor controller is linearly reduced f Reaching the upper temperature protection threshold T p1 The output power of the motor controller is limited to 0.
In the protection system of the filter capacitor provided by this embodiment, the filter capacitor is a polypropylene film capacitor, and is mainly applied to a motor controller, but is also applicable to other types of capacitors, and meanwhile, the protection system of the filter capacitor is not limited to a motor controller product, and in an inverter system, the filter capacitor used on the dc side can be protected by using a similar protection system.
Based on the same inventive concept, an embodiment of the present invention further provides a motor controller, including: a filter capacitor protection system for dynamically acquiring and protecting an absolute temperature of a filter capacitor in real time, comprising: the device comprises an input module, an analysis module, a threshold setting module and an output module, wherein the input module is used for acquiring input information under a certain working condition and transmitting the input information to the analysis module; the analysis module analyzes according to the input information to obtain the absolute temperature of the filter capacitor; the threshold setting module is used for setting a temperature protection threshold corresponding to the working condition; the output module judges the magnitude relation between the absolute temperature and the temperature protection threshold value and controls the output information of the motor controller according to the judgment result.
In summary, according to the protection method, the protection system and the motor controller for the filter capacitor provided by the invention, the absolute temperature of the filter capacitor is dynamically obtained in real time by a physical modeling method, and the output capability of the motor controller is controlled according to the relationship between the obtained absolute temperature value of the filter capacitor and the set temperature protection threshold, so as to perform overheat protection on the filter capacitor. The invention protects the filter capacitor by a physical modeling method, and avoids the influence of hot spot (maximum value of absolute temperature) transfer caused by working condition change of the filter capacitor.
Meanwhile, compared with the absolute temperature (hot spot) of the filter capacitor obtained by the traditional temperature sensor, the physical modeling has stronger robustness and consistency, and the inaccuracy of temperature measurement data caused by the inconsistency of the characteristics of the temperature sensor or the aging of the service life of the temperature sensor can be effectively avoided. In addition, the protection method of the filter capacitor provided by the invention can effectively replace a temperature sensor, and the production cost is reduced.
It will be apparent to those skilled in the art that various changes and modifications may be made in the invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (16)
1. A protection method of a filter capacitor is used for carrying out overheat protection on the filter capacitor in a motor controller, and is characterized by comprising the following steps:
collecting data information of the filter capacitor under various working conditions;
carrying out physical modeling on the data information to form a physical model corresponding to the working condition for acquiring the absolute temperature of the filter capacitor;
setting a temperature protection threshold value of the filter capacitor corresponding to the working condition;
acquiring input information under a certain working condition and inputting a physical model corresponding to the working condition to acquire the absolute temperature of the filter capacitor; and the number of the first and second groups,
judging the magnitude relation between the absolute temperature of the filter capacitor and a temperature protection threshold value under the working condition and controlling the output information of the motor controller according to the judgment result;
the data information and the input information each include: ripple current of a filter capacitor, direct current of a direct current side and water cooling temperature;
the process of acquiring the absolute temperature of the filter capacitor includes:
acquiring ripple current of a filter capacitor and direct current of a direct current side under a certain working condition, and inputting a physical model corresponding to the working condition to acquire an absolute temperature rise numerical value of the filter capacitor;
and acquiring the water cooling temperature, and calculating the absolute temperature of the filter capacitor according to the water cooling temperature and the absolute temperature rise value.
2. The filter capacitor protection method according to claim 1, wherein the water-cooling temperature is obtained by a water temperature sensor in a water-cooling system.
3. The filter capacitor protection method of claim 1, wherein the outputting information comprises: output power of the motor controller.
4. The filter capacitor protection method according to claim 3, wherein when the absolute temperature of the filter capacitor is lower than the temperature protection threshold, the output power of the motor controller is not limited; when the absolute temperature of the filter capacitor exceeds the temperature protection threshold, the motor controller correspondingly reduces the actual output power on the basis of the rated output power.
5. The filter capacitor protection method according to claim 4, wherein the temperature protection threshold includes an upper temperature protection threshold and a lower temperature protection threshold, the output power of the motor controller decreases linearly when the absolute temperature of the filter capacitor exceeds the lower temperature protection threshold and does not reach the upper temperature protection threshold, and the output power of the motor controller is limited to 0 when the absolute temperature of the filter capacitor reaches the upper temperature protection threshold.
6. The method of claim 1, wherein the filter capacitor is a thin film capacitor.
7. The method of claim 6, wherein the filter capacitor is a polypropylene film capacitor.
8. A filter capacitor protection system for dynamically acquiring and protecting an absolute temperature of a filter capacitor in a motor controller in real time, comprising: an input module, an analysis module, a threshold setting module and an output module,
the input module is used for acquiring input information under a certain working condition and transmitting the input information to the analysis module;
the analysis module analyzes according to the input information to obtain the absolute temperature of the filter capacitor;
the threshold setting module is used for setting a temperature protection threshold corresponding to the working condition;
the output module judges the magnitude relation between the absolute temperature and the temperature protection threshold value and controls the output information of the motor controller according to the judgment result;
the input information includes: ripple current of a filter capacitor, direct current of a direct current side and water cooling temperature;
the process of obtaining the absolute temperature of the filter capacitor includes:
the method comprises the following steps that an input module acquires ripple current of a filter capacitor, direct current on a direct current side and water cooling temperature under a certain working condition, and inputs the ripple current of the filter capacitor, the direct current on the direct current side and the water cooling temperature to an analysis module;
the analysis module inputs the ripple current of the filter capacitor and the direct current of the direct current side into a physical model corresponding to the working condition so as to obtain an absolute temperature rise value of the filter capacitor, and the absolute temperature of the filter capacitor is calculated according to the water cooling temperature and the absolute temperature rise value.
9. The filter capacitor protection system of claim 8, wherein the analysis module comprises physical models corresponding to different operating conditions of the filter capacitor, and the physical models are formed by physical modeling in a manner that specific input information is combined with calibration results.
10. The filter capacitor protection system of claim 8, wherein the water-cooled temperature is obtained by a water temperature sensor in a water-cooled system.
11. The filter capacitor protection system of claim 8, wherein the output information comprises: output power of the motor controller.
12. The filter capacitor protection system of claim 11, wherein the output module does not limit the output power of the motor controller when the absolute temperature of the filter capacitor is below the temperature protection threshold; when the absolute temperature of the filter capacitor exceeds the temperature protection threshold, the output module correspondingly reduces the actual output power on the basis of the rated output power of the motor controller.
13. The filter capacitor protection system of claim 12, wherein the temperature protection threshold comprises an upper temperature protection threshold and a lower temperature protection threshold, the output module controls the output power of the motor controller to decrease linearly when the absolute temperature of the filter capacitor exceeds the lower temperature protection threshold and does not reach the upper temperature protection threshold, and the output module limits the output power of the motor controller to 0 when the absolute temperature of the filter capacitor reaches the upper temperature protection threshold.
14. The filter capacitor protection system of claim 8, wherein the filter capacitor is a thin film capacitor.
15. The filter capacitor protection system of claim 8, wherein the filter capacitor is a polypropylene film capacitor.
16. A motor controller, comprising: a filter capacitor protection system for dynamically acquiring and protecting an absolute temperature of a filter capacitor in real time, comprising: the device comprises an input module, an analysis module, a threshold setting module and an output module, wherein the input module is used for acquiring input information under a certain working condition and transmitting the input information to the analysis module; the analysis module analyzes according to the input information to obtain the absolute temperature of the filter capacitor; the threshold setting module is used for setting a temperature protection threshold corresponding to the working condition; the output module judges the magnitude relation between the absolute temperature and the temperature protection threshold value and controls the output information of the motor controller according to the judgment result;
the input information includes: ripple current of a filter capacitor, direct current of a direct current side and water cooling temperature;
the process of acquiring the absolute temperature of the filter capacitor includes:
the method comprises the following steps that an input module acquires ripple current of a filter capacitor, direct current on a direct current side and water cooling temperature under a certain working condition, and inputs the ripple current of the filter capacitor, the direct current on the direct current side and the water cooling temperature to an analysis module;
the analysis module inputs the ripple current of the filter capacitor and the direct current of the direct current side into a physical model corresponding to the working condition so as to obtain an absolute temperature rise value of the filter capacitor, and the absolute temperature of the filter capacitor is calculated according to the water cooling temperature and the absolute temperature rise value.
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