CN112736848A - Overcurrent protection method and device for motor controller - Google Patents
Overcurrent protection method and device for motor controller Download PDFInfo
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- CN112736848A CN112736848A CN202011211672.9A CN202011211672A CN112736848A CN 112736848 A CN112736848 A CN 112736848A CN 202011211672 A CN202011211672 A CN 202011211672A CN 112736848 A CN112736848 A CN 112736848A
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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
- H02H7/0822—Integrated protection, motor control centres
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
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Abstract
The invention discloses an overcurrent protection method of a motor controller, which belongs to the field of motor control and comprises the following steps: step S1: continuously collecting and processing three-phase current of the motor controller every a preset sampling period, and continuously outputting the processed three-phase current as a current sampling value; step S2: according to the plurality of current sampling values, current prediction is carried out through a preset fitting current prediction equation to obtain a predicted current value corresponding to the next sampling period; step S3: judging whether the predicted current value is greater than a preset protection threshold value: if yes, turning off the control pulse width modulation signal; step S4: judging whether the current sampling value corresponding to the current sampling period is smaller than a preset recovery threshold value: if so, the control pulse width modulation signal is normally output, and then the process returns to step S3. The invention has the beneficial effects that: protection actions are triggered in advance through a prediction algorithm, the risk of damage is reduced, online recovery is provided, and long-time shutdown is avoided.
Description
Technical Field
The invention relates to the field of motor control, in particular to an overcurrent protection method and device of a motor controller.
Background
The motor current overcurrent generally includes a short-time current overcurrent and a long-time current overcurrent. Short-time current overcurrent is generally caused by instantaneous damage or electromagnetic interference of a device, and the mutation time is extremely short; however, due to controller software reasons such as parameter mismatch or control quantity saturation, the long-term overcurrent generally has a process that the current gradually increases, and the time is relatively long. At present, the current is detected by a hardware overcurrent detection circuit, and when the real-time current reaches a preset overcurrent threshold value, a control signal is cut off, a current loop is disconnected, and protection is realized.
In the traditional current prediction algorithm, a corresponding motor model observer is set up, and real current is compared with a current error output by the observer on line to correct the current error in real time, so that the accuracy of the model is ensured. However, the accuracy of the method is greatly influenced by model parameters, certain convergence time is needed, errors are relatively large under the condition that the operation condition changes violently, meanwhile, the algorithm is complex, the real-time calculation amount is large, the requirement on the calculation capacity of a control chip is high, and the engineering application value is not high.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides an overcurrent protection method of a motor controller, which solves the technical problems.
The technical problem solved by the invention can be realized by adopting the following technical scheme:
an overcurrent protection method for a motor controller, the protection method comprising:
step S1: continuously collecting and processing three-phase current of the motor controller every a preset sampling period, and continuously outputting the processed three-phase current as a current sampling value;
step S2: according to the current sampling values, current prediction is carried out through a preset fitting current prediction equation to obtain a predicted current value corresponding to the next sampling period;
step S3: judging whether the predicted current value is greater than a preset protection threshold value:
if yes, the control pulse width modulation signal is turned off, and then the step S4 is turned to;
if not, returning to the step S2;
step S4: judging whether the current sampling value corresponding to the current sampling period is smaller than a preset recovery threshold value:
if yes, normally outputting the control pulse width modulation signal, and then returning to the step S3;
if not, the process returns to step S5.
Preferably, in the step S2, the fitting current prediction equation is specifically as follows:
X(n+1)＝X(n-2)-3*X(n-1)+3*X(n)
wherein:
X(n+1)is the predicted current value;
X(n)the current sampling value corresponding to the current sampling period is obtained;
X(n-1)the current sampling value corresponding to the previous sampling period;
X(n-2)and current sampling values corresponding to the first two sampling periods.
Preferably, the step S1 further includes:
step S11, coordinate transformation is carried out on the three-phase current, and a one-phase current vector value is output;
and step S12, performing low-frequency filtering on the phase current vector value, and outputting the current sampling value.
The utility model provides an overcurrent protection device, overcurrent protection device is applied to a motor controller, specifically includes:
the acquisition module is used for continuously acquiring and continuously outputting the three-phase current of the motor controller every a preset sampling period;
the processing module is connected with the acquisition module and is used for processing the three-phase current and continuously outputting a current sampling value;
the prediction module is connected with the processing module and used for predicting current through a preset fitting current prediction equation according to the current sampling values to obtain a predicted current value corresponding to the next sampling period;
the first judgment module is connected with the prediction module, continuously judges whether the predicted current value is greater than a preset protection threshold value or not, and outputs a first judgment result;
the overcurrent protection module is connected with the first judgment module and is used for switching off a control pulse width modulation signal when the predicted current value is greater than the preset protection threshold value according to the first judgment result;
the second judgment module is respectively connected with the processing module and the overcurrent protection module, and is used for judging whether the current sampling value is smaller than a preset recovery threshold value or not and outputting a second judgment result when the overcurrent protection module turns off the control pulse width modulation signal;
and the overcurrent protection module restores the control pulse width modulation signal when the current sampling value is smaller than a preset restoration threshold value according to the second judgment result.
Preferably, the processing module further comprises:
the coordinate transformation unit is used for carrying out coordinate transformation on the three-phase current and outputting a one-phase current vector value;
and the filtering unit is connected with the coordinate transformation unit and is used for carrying out low-frequency filtering on the phase current vector value and outputting the current sampling value.
Preferably, the filtering unit is implemented using a low-pass filter.
Preferably, the prediction module further comprises a cache unit;
the buffer unit is used for receiving the current sampling values according to a time sequence and buffering the current sampling values.
The technical scheme of the invention has the beneficial effects that:
the overcurrent protection method of the motor controller is provided, protection is carried out by triggering protection action in advance when the current does not reach a threshold value according to a current prediction equation, the risk of damage is reduced, the current prediction algorithm is simple, the real-time calculation amount is small, the requirement on the calculation capacity is low, the engineering application value is high, online recovery is provided, and long-time shutdown is avoided.
Drawings
FIG. 1 is a flow chart of an over-current protection method according to the present invention;
FIG. 2 is a flowchart of step S1 according to the present invention;
FIG. 3 is a block diagram of an overcurrent protection apparatus according to the present invention;
FIG. 4 is a block diagram of a processing module according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.
The invention includes an overcurrent protection method and a device of a motor controller, as shown in fig. 1 and 4, the overcurrent protection method of the motor controller comprises the following steps:
step S1: continuously collecting and processing three-phase current of the motor controller every a preset sampling period, and continuously outputting the processed three-phase current as a current sampling value;
step S2: according to the plurality of current sampling values, current prediction is carried out through a preset fitting current prediction equation to obtain a predicted current value corresponding to the next sampling period;
step S3: judging whether the predicted current value is greater than a preset protection threshold value:
if yes, the control pulse width modulation signal is turned off, and then the step S4 is turned to;
if not, returning to the step S2;
step S4: judging whether the current sampling value corresponding to the current sampling period is smaller than a preset recovery threshold value:
if yes, normally outputting a control pulse width modulation signal, and then returning to the step S3;
if not, the process returns to step S5.
Specifically, the phase difference of three components of the three-phase current is one third of one period or 120 ° phase angle in sequence.
The overcurrent protection method comprises the steps of continuously collecting three-phase current of a motor controller at intervals of a preset sampling period through a current sensor, processing the three-phase current to obtain three-phase current sampling values, calculating a predicted current value corresponding to the next sampling period through a current prediction equation according to the current sampling value corresponding to the current sampling period, the current sampling value corresponding to the previous sampling period and the current sampling values corresponding to the previous two sampling periods, entering overcurrent protection action when the predicted current value is larger than a preset protection threshold value, cutting off a pulse width modulation signal, stopping output, and recovering normal output when the current sampling value corresponding to the current sampling period is smaller than a preset recovery threshold value.
Further, in step S2, the fitting current prediction equation is specifically as follows:
X(n+1)＝X(n-2)-3*X(n-1)+3*X(n)
wherein:
X(n+1)to predict the current value;
X(n)the current sampling value is corresponding to the current sampling period;
X(n-1)the current sampling value corresponding to the previous sampling period;
X(n-2)and current sampling values corresponding to the first two sampling periods.
Further, as shown in fig. 2, step S1 further includes:
step S11, coordinate transformation is carried out on the three-phase current, and a one-phase current vector value is output;
and step S12, low-frequency filtering is carried out on the phase current vector value, and a current sampling value is output.
Specifically, coordinate transformation refers to the transformation of coordinates of one coordinate system into coordinates of another coordinate system. And carrying out coordinate conversion on the acquired three-phase current, processing the three-phase current in a two-phase static D, Q coordinate system converted from the three-phase static coordinate system to obtain a phase current vector value, carrying out low-frequency filtering on the phase current vector value, and outputting a current sampling value corresponding to the current sampling period.
An overcurrent protection device is applied to a motor controller, and as shown in fig. 3, the device specifically comprises:
the acquisition module 1 is used for continuously acquiring and continuously outputting the three-phase current of the motor controller every a preset sampling period;
the processing module 2 is connected with the acquisition module 1 and is used for processing the three-phase current and continuously outputting a current sampling value;
the prediction module 3 is connected with the processing module 2 and used for predicting the current through a preset fitting current prediction equation according to the plurality of current sampling values to obtain a predicted current value corresponding to the next sampling period;
the first judgment module 4 is connected with the prediction module 3, continuously judges whether the predicted current value is greater than a preset protection threshold value or not, and outputs a first judgment result;
the overcurrent protection module 5 is connected with the first judgment module 4, and turns off the control pulse width modulation signal when the predicted current value is greater than the preset protection threshold value according to the first judgment result;
the second judgment module 6 is respectively connected with the processing module 2 and the overcurrent protection module 5, and when the overcurrent protection module 5 turns off the control pulse width modulation signal, judges whether the current sampling value is smaller than a preset recovery threshold value and outputs a second judgment result;
and the overcurrent protection module 5 recovers the control pulse width modulation signal when the current sampling value is smaller than a preset recovery threshold value according to the second judgment result.
Specifically, the overcurrent protection device specifically includes:
the acquisition module 1 is used for continuously acquiring and continuously outputting the three-phase current of the motor controller every a preset sampling period;
the processing module 2 is used for processing the three-phase current and continuously outputting a current sampling value;
the prediction module 3 is used for predicting current through a preset fitting current prediction equation according to a plurality of current sampling values to obtain a predicted current value corresponding to the next sampling period;
the first judgment module 4 continuously judges whether the predicted current value is greater than a preset protection threshold value or not and outputs a first judgment result;
the overcurrent protection module 5 is used for switching off the control pulse width modulation signal when the predicted current value is greater than the preset protection threshold value according to the first judgment result;
and the second judgment module 6 judges whether the current sampling value is smaller than a preset recovery threshold value or not when the overcurrent protection module 5 turns off the control pulse width modulation signal, and outputs a second judgment result.
Further, as shown in fig. 4, the processing module 2 further includes:
the coordinate transformation unit 21 is used for carrying out coordinate transformation on the three-phase current and outputting a one-phase current vector value;
and the filtering unit 22 is connected with the coordinate transformation unit 21 and is used for performing low-frequency filtering on the phase current vector value and outputting a current sampling value.
Further, the filtering unit 22 is implemented using a low pass filter.
Furthermore, the prediction module 3 further includes a buffer unit 31;
the buffer unit 31 is configured to receive and buffer the current sample values in time sequence.
The technical scheme of the invention has the beneficial effects that:
the overcurrent protection method of the motor controller is provided, protection is carried out by triggering protection action in advance when the current does not reach a threshold value according to a current prediction equation, the risk of damage is reduced, the current prediction algorithm is simple, the real-time calculation amount is small, the requirement on the calculation capacity is low, the engineering application value is high, online recovery is provided, and long-time shutdown is avoided.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (7)
1. An overcurrent protection method for a motor controller, the protection method comprising:
step S1: continuously collecting and processing three-phase current of the motor controller every a preset sampling period, and continuously outputting the processed three-phase current as a current sampling value;
step S2: according to the current sampling values, current prediction is carried out through a preset fitting current prediction equation to obtain a predicted current value corresponding to the next sampling period;
step S3: judging whether the predicted current value is greater than a preset protection threshold value:
if yes, the control pulse width modulation signal is turned off, and then the step S4 is turned to;
if not, returning to the step S2;
step S4: judging whether the current sampling value corresponding to the current sampling period is smaller than a preset recovery threshold value:
if yes, normally outputting the control pulse width modulation signal, and then returning to the step S3;
if not, the process returns to step S3.
2. The overcurrent protection method according to claim 1, wherein in the step S2, the fitted current prediction equation is specifically as follows:
X(n+1)＝X(n-2)-3*X(n-1)+3*X(n)
wherein:
X(n+1)is the predicted current value;
X(n)the current sampling value corresponding to the current sampling period is obtained;
X(n-1)the current sampling value corresponding to the previous sampling period;
X(n-2)and current sampling values corresponding to the first two sampling periods.
3. The overcurrent protection method according to claim 1, wherein said step S1 further comprises:
step S11, coordinate transformation is carried out on the three-phase current, and a one-phase current vector value is output;
and step S12, performing low-frequency filtering on the phase current vector value, and outputting the current sampling value.
4. An overcurrent protection device, which is used in the overcurrent protection method according to any one of claims 1 to 3, wherein the overcurrent protection device is applied to a motor controller, and specifically comprises:
the acquisition module is used for continuously acquiring and continuously outputting the three-phase current of the motor controller every a preset sampling period;
the processing module is connected with the acquisition module and is used for processing the three-phase current and continuously outputting a current sampling value;
the prediction module is connected with the processing module and used for predicting current through a preset fitting current prediction equation according to the current sampling values to obtain a predicted current value corresponding to the next sampling period;
the first judgment module is connected with the prediction module, continuously judges whether the predicted current value is greater than a preset protection threshold value or not, and outputs a first judgment result;
the overcurrent protection module is connected with the first judgment module and is used for switching off a control pulse width modulation signal when the predicted current value is greater than the preset protection threshold value according to the first judgment result;
the second judgment module is respectively connected with the processing module and the overcurrent protection module, and is used for judging whether the current sampling value is smaller than a preset recovery threshold value or not and outputting a second judgment result when the overcurrent protection module turns off the control pulse width modulation signal;
and the overcurrent protection module restores the control pulse width modulation signal when the current sampling value is smaller than a preset restoration threshold value according to the second judgment result.
5. The over-current protection device according to claim 4, wherein the processing module further comprises:
the coordinate transformation unit is used for carrying out coordinate transformation on the three-phase current and outputting a one-phase current vector value;
and the filtering unit is connected with the coordinate transformation unit and is used for carrying out low-frequency filtering on the phase current vector value and outputting the current sampling value.
6. The overcurrent protection apparatus as set forth in claim 5, wherein said filter unit is implemented as a low-pass filter.
7. The over-current protection device as claimed in claim 4, wherein said prediction module further comprises a buffer unit;
the buffer unit is used for receiving the current sampling values according to a time sequence and buffering the current sampling values.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106370922A (en) * | 2016-08-31 | 2017-02-01 | 中国科学院空间应用工程与技术中心 | Solid state power controller and fault current record method |
| CN107665691A (en) * | 2017-11-13 | 2018-02-06 | 深圳市华星光电技术有限公司 | The overcurrent protection method and over-current protection system of liquid crystal display panel |
| CN109742733A (en) * | 2019-02-22 | 2019-05-10 | 深圳市道通智能航空技术有限公司 | Over-current protection method, device, system and unmanned vehicle |
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- 2020-11-03 CN CN202011211672.9A patent/CN112736848A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106370922A (en) * | 2016-08-31 | 2017-02-01 | 中国科学院空间应用工程与技术中心 | Solid state power controller and fault current record method |
| CN107665691A (en) * | 2017-11-13 | 2018-02-06 | 深圳市华星光电技术有限公司 | The overcurrent protection method and over-current protection system of liquid crystal display panel |
| CN109742733A (en) * | 2019-02-22 | 2019-05-10 | 深圳市道通智能航空技术有限公司 | Over-current protection method, device, system and unmanned vehicle |
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