Method for calculating supply current of switched reluctance motor based on three-phase phase currents

Abstract

The present invention relates to the technical field of switched reluctance motor control, and particularly relates to a method for calculating the supply current of a switched reluctance motor through three-phase phase currents. The method is applied to a switched reluctance motor controller, and the method includes the following steps: Step 1: Set three independent phase current sensors in the switched reluctance motor controller, and the switched reluctance motor controller rotates the switched reluctance motor by continuously switching the direction of the drive current; Step 2: Save the instantaneous sampling values of the three-phase phase currents; Step 3: Calculate the weights of the three-phase phase currents in the current cycle; Step 4: Calculate the estimated value of the supply current; Step 5: Perform average value filtering processing on the preliminary estimated value of the supply current; Step 6: Predict and calculate the switching states of the three-phase switching tubes in the next cycle, specifically, according to the actual measured values of the three-phase currents in the current cycle, predict and calculate the switching states of the three-phase switching tubes in the next cycle.

Description

Technical Field

[0001] The present invention relates to the technical field of switched reluctance motor control, and particularly to a method for calculating the supply current of a switched reluctance motor through three-phase phase currents. Background Art

[0002] The design of a switched reluctance motor controller usually requires the installation of three independent phase current sensors to monitor the current status of each phase of the motor. In addition, in order to comprehensively monitor the supply current, an additional supply current sensor needs to be designed and installed.

[0003] This design has the following deficiencies: 1. Structural complexity: The integration of multiple sensors increases the complexity of the controller, resulting in an increased difficulty in system design and also reducing the stability of the system; 2. Cost issue: The added sensors not only increase the material cost but may also increase the manufacturing and maintenance costs, thus affecting the economy of the product; 3. Electromagnetic interference problem: The sensors may generate electromagnetic interference during operation. This interference will affect the normal operation of other components inside the controller and further affect the stability and reliability of the entire system. Summary of the Invention

[0004] The purpose of the present invention is to provide a technical solution to solve the problems in the background art.

[0005] The technical solution of the present invention is: A method for calculating the supply current of a switched reluctance motor through three-phase phase currents, the method is applied to a switched reluctance motor controller, and the method includes the following steps:

[0006] Step 1: Set three independent phase current sensors in the switched reluctance motor controller, and the switched reluctance motor controller rotates the switched reluctance motor by continuously switching the direction of the drive current;

[0007] Step 2: Save the instantaneous sampling values of the three-phase phase currents;

[0008] Step 3: Calculate the weights of the three-phase phase currents in the current cycle;

[0009] Step 4: Calculate the estimated value of the supply current;

[0010] Step 5: Perform average filtering processing on the preliminary estimated value of the supply current;

[0011] Step 6: Predict and calculate the switching states of the three-phase switching tubes in the next cycle, specifically, according to the actual measured values of the three-phase currents in the current cycle, predict and calculate the switching states of the three-phase switching tubes in the next cycle.

[0012] The said Step 2 includes the following steps:

[0013] In the ADC interrupt program, the instantaneous sampling values of the three-phase phase currents are saved in real time at a frequency of 20 kHz;

[0014] Let the three-phase currents be I a 、I b 、I c ;

[0015] Step three includes the following steps:

[0016] According to the switching states of the three-phase switching tubes recorded in the previous cycle of the ADC interrupt program, calculate the corresponding weights of the three-phase phase currents in calculating the supply current in the current cycle. Let the weights be W a 、W b 、W c ;

[0017] The weight values are 1, -1 or 0.

[0018] Step four includes the following steps:

[0019] Multiply the phase current values obtained in step one by their weight values calculated in step two, and accumulate the results to obtain a preliminary estimated value of the supply current I est , that is: I est =W a I a +W b I b +W c I c .

[0020] Step six includes the following steps:

[0021] Perform average filtering on the preliminary estimated value of the supply current obtained in step four to obtain the supply input current I in .

[0022] The switched reluctance motor controller realizes the switching of the directions of the three-phase currents through three current chopping circuits, thereby realizing the control of the drive current. The three current chopping circuits have the same structure. The current chopping circuit includes power switch one, power switch two, diode one, diode two and an inductor. The emitter of power switch one is connected to the negative electrode of diode one. The positive electrode of diode two is connected to the collector of power switch two. The collector of power switch one is connected to the negative electrode of diode two. The emitter of power switch two is connected to the positive electrode of diode one. The two ends of the inductor are respectively connected to the negative electrode of diode one and the positive electrode of diode two. The three current chopping circuits are connected in parallel across the power supply.

[0023] The steps of performing average filtering on the preliminary estimated value of the supply current obtained in step four to obtain the supply input current include the following steps:

[0024] Let the time series of a measured phase current be I1, I2, I3, ..., I T , and the number of terms for moving average be N, where N < T and T is the end time point of current acquisition;

[0025] Then the moving average value of the current at time t is:

[0026]

[0027] Establish a prediction model for the current:

[0028] where t = N, N + 1, …, N + n; 4 ≤ N ≤ 500;

[0029] Predict the values of the phase current and the supply current at the next moment through the current prediction model.

[0030] Specifically, according to the actual measured values of the three-phase currents in the current cycle, predicting and calculating the switching states of the three-phase switching tubes in the next cycle includes the following steps:

[0031] Establish a prediction model for the supply current:

[0032] Predict the supply current at the next moment and the three phase currents at the next moment through the current prediction model;

[0033] Obtain the predicted values of W a , W b and W c , and then predict the switching states of power switch one and power switch two.

[0034] The predicting the three phase currents at the next moment through the current prediction model includes the following steps:

[0035] Take the historically measured phase currents as the input quantities of the circuit prediction model, and output the predicted phase current values I at+1 , I bt+1 and I ct+1 ;

[0036] Set the phase current threshold ΔI s . If the difference between the predicted value and the actual measured value of the phase current is within the threshold range, the predicted phase current value is valid;

[0037] That is, |I bt+1 - I b | ≤ ΔI s , |I at+1 - I a | ≤ ΔI s , |I ct+1 - Ic |≤ΔI s where I a 、I b 、I c are the actually measured phase current values.

[0038] Specifically, predicting and calculating the switching states of the three-phase switching tubes in the next cycle according to the actually measured values of the three-phase currents in the current cycle further includes the following steps:

[0039] Set the minimum threshold I min and the maximum threshold I max ;

[0040] Obtain the three phase currents I at 、I bt 、I ct in the current cycle;

[0041] Compare the three phase currents with the minimum threshold respectively. If it is less than the minimum threshold, set the first power switch and the second power switch to be turned on simultaneously, and the corresponding weight value is 1 at this time; if it is greater than the maximum threshold, set the first power switch and the second power switch to be turned off simultaneously, and the corresponding weight value is -1 at this time; if it is between the maximum threshold and the minimum threshold, the first power switch and the second power switch are in a state of one conduction and one cut-off, and the weight value is 0 at this time.

[0042] Advantages of the present invention:

[0043] 1. The present invention optimizes the current detection scheme. By adopting the instantaneous sampling values of the three-phase currents of the motor and calculating the power input current within the shortest control cycle of 50 microseconds, it realizes fast-response current monitoring. By omitting the power current sensor, it simplifies the structural design of the controller, reduces the number of system components, and reduces the complexity of design and manufacturing, thereby improving the robustness of the system; omitting the power current sensor directly reduces the manufacturing cost of the controller, including material cost and production cost, and improves the economy.

[0044] 2. The present invention reduces the potential sources of electromagnetic interference by reducing the number of sensors, thereby enhancing the stability and reliability of the entire control system in a high electromagnetic interference environment. Reducing the use of sensors helps to achieve a more compact and lightweight controller design, meeting the requirements of application scenarios with strict restrictions on the volume and weight of equipment. Description of the Drawings

[0045] Figure 1 is a schematic flow chart of a method for calculating the power current of a switched reluctance motor through three-phase phase currents according to the present invention;

[0046] Figure 2 is a schematic diagram of the phase current flow direction according to the present inventionFigure 1 ;

[0047] Figure 3 Schematic diagram of the phase current flow direction of the present invention Figure 2 ;

[0048] Figure 4 Schematic diagram of the phase current flow direction of the present invention Figure 3 。

[0049] In the drawings: G1 represents the first power switch, G2 represents the second power switch, D1 represents the first diode, and D2 represents the second diode. Specific embodiments

[0050] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples, and those skilled in the art can think of other obvious variations. The basic principles defined in the following description of the present invention can be applied to other implementation schemes, variant schemes, improvement schemes, equivalent schemes, and other technical schemes that do not depart from the spirit and scope of the present invention.

[0051] It can be understood that the term "a" should be understood as "at least one" or "one or more". That is, in one embodiment, the number of an element can be one, while in other embodiments, the number of the element can be multiple. The term "a" cannot be understood as a limitation on the number.

[0052] Embodiment 1:

[0053] Referring to Figure 1 , the present invention provides a technical solution: a method for calculating the power supply current through the three-phase phase current of a switched reluctance motor. The method is applied to a switched reluctance motor controller, and the method includes the following steps:

[0054] Step 1: Set three independent phase current sensors in the switched reluctance motor controller. The switched reluctance motor controller rotates the switched reluctance motor by continuously switching the direction of the drive current;

[0055] Step 2: Save the instantaneous sampling values of the three-phase phase current;

[0056] Step 3: Calculate the weights of the three-phase phase current in the current cycle;

[0057] Step 4: Calculate the estimated value of the power supply current;

[0058] Step 5: Perform average value filtering processing on the preliminary estimated value of the power supply current;

[0059] Step 6: Predict and calculate the switching states of the three-phase switching tubes in the next cycle, specifically, predict and calculate the switching states of the three-phase switching tubes in the next cycle according to the actual measured values of the three-phase currents in the current cycle.

[0060] Step 2 includes the following steps:

[0061] In the ADC interrupt program, the instantaneous sampling values of the three-phase phase currents are saved in real time at a frequency of 20 kHz;

[0062] Let the three-phase currents be I a , I b , I c ;

[0063] Step 3 includes the following steps:

[0064] According to the switching states of the three-phase switching tubes recorded in the previous cycle of the ADC interrupt program, calculate the corresponding weights of the three-phase phase currents in calculating the supply current in the current cycle. Let the weights be W a , W b , W c ;

[0065] The weight values are 1, -1, or 0.

[0066] Step 4 includes the following steps:

[0067] Multiply the phase current values obtained in Step 1 by their weight values calculated in Step 2, and accumulate the results to obtain a preliminary estimated value of the supply current I est , that is: I est = W a I a + W b I b + W c I c .

[0068] Step 6 includes the following steps:

[0069] Perform average value filtering on the preliminary estimated value of the supply current obtained in Step 4 to obtain the supply input current I in .

[0070] The switched reluctance motor controller realizes the switching of the directions of the three-phase currents through three current chopping circuits, thereby realizing the control of the drive current. The three current chopping circuits have the same structure. The current chopping circuit includes power switch one, power switch two, diode one, diode two, and an inductor. The emitter of power switch one is connected to the negative electrode of diode one. The positive electrode of diode two is connected to the collector of power switch two. The collector of power switch one is connected to the negative electrode of diode two. The emitter of power switch two is connected to the positive electrode of diode one. The two ends of the inductor are respectively connected to the negative electrode of diode one and the positive electrode of diode two. The three current chopping circuits are connected in parallel across the power supply.

[0071] The process of obtaining the power input current by performing mean filtering on the preliminary power current estimation value obtained in Step 4 includes the following steps:

[0072] Let the time series of a measured phase current be I1, I2, I3,..., I T , and take the number of terms for the moving average as N, and N < T, where T is the end time point of current acquisition;

[0073] Then the moving average value of the current at time t is:

[0074]

[0075] Establish a prediction model for the current:

[0076]

[0077] Predict the values of the phase current and the power current at the next moment through the current prediction model.

[0078] Specifically, predicting and calculating the switching states of the three-phase switching tubes in the next cycle according to the actual measured values of the three-phase currents in the current cycle includes the following steps:

[0079] Establish a power current prediction model:

[0080] Predict the power current at the next moment and the three phase currents at the next moment through the current prediction model;

[0081] Obtain the predicted values of W a , W b and W c , and then predict the switching states of power switch one and power switch two.

[0082] The process of predicting the three phase currents at the next moment through the current prediction model includes the following steps:

[0083] Use the historically measured phase currents as the input quantities of the circuit prediction model, and output the predicted phase current values I at+1 , I bt+1 and I ct+1 ;

[0084] Set the phase current threshold ΔI s . If the difference between the predicted value and the actual measured value of the phase current is within the threshold range, the predicted phase current value is valid;

[0085] That is, |I bt+1 -I b | ≤ ΔI s 、|I at+1 -Ia |≤ΔI s 、|I ct+1 -I c |≤ΔI s , where I a 、I b 、I c are the actually measured phase current values.

[0086] Embodiment 2:

[0087] Referring to Figure 1 , on the basis of Embodiment 1, this embodiment proposes a method for setting the switching states of Power Switch 1 and Power Switch 2:

[0088] Set the minimum threshold I min and the maximum threshold I max ;

[0089] Obtain the three phase currents I at 、I bt 、I ct in the current cycle;

[0090] Compare the three phase currents with the minimum threshold respectively. If it is less than the minimum threshold, set Power Switch 1 and Power Switch 2 to turn on simultaneously, and the corresponding weight value is 1 at this time; if it is greater than the maximum threshold, set Power Switch 1 and Power Switch 2 to turn off simultaneously, and the corresponding weight value is -1 at this time; if it is between the maximum threshold and the minimum threshold, then Power Switch 1 and Power Switch 2 are in a state where one is on and the other is off, and the weight value is 0 at this time.

[0091] When Power Switch 1 and Power Switch 2 are turned on simultaneously, the current flow direction is as Figure 2 shown, and the weight value is 1 at this time; when Power Switch 1 and Power Switch 2 are turned off simultaneously, the current flow direction is as Figure 3 shown, and the weight value is -1 at this time; when only one of Power Switch 1 and Power Switch 2 is on, the current flow direction is as Figure 4 shown, and the weight value is 0 at this time.

[0092] Embodiments disclosed by the present invention. The processes described above with reference to the flowcharts can be implemented as computer software programs. Embodiments disclosed by the present invention include a computer program product, which includes a computer program carried on a computer-readable medium. The computer program contains program codes for performing the methods shown in the flowcharts. In such an embodiment, the computer program can be downloaded and installed from a network through a communication part, and / or installed from a removable medium. When the computer program is executed by a central processing unit (CPU), the above-mentioned functions defined in the methods of the present application are performed. It should be noted that the computer-readable medium in the present application can be a computer-readable signal medium, a computer-readable storage medium, or any combination of the two. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples of a computer-readable storage medium can include, but are not limited to: an electrical connection having one or more wire segments, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable storage medium can be any tangible medium that contains or stores a program, and this program can be used by or in combination with an instruction execution system, apparatus, or device. In the present application, a computer-readable signal medium can include a data signal propagated in a baseband or as part of a carrier wave, which carries computer-readable program codes. Such a propagated data signal can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, and this computer-readable medium can send, propagate, or transmit a program for use by or in combination with an instruction execution system, apparatus, or device. The program codes contained on the computer-readable medium can be transmitted by any appropriate medium, including but not limited to: wireless segments, wire segments, optical cables, RF, etc., or any suitable combination of the above.

[0093] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagram may represent a module, a segment of a program, or a portion of code that contains one or more executable instructions for implementing a specified logical function. It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur in a different order than that noted in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions.

[0094] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments. Without departing from the said principles, the embodiments of the present invention may have any variations or modifications.

Claims

1. A method for calculating the power supply current of a switched reluctance motor through three-phase current, the method being applied to a switched reluctance motor controller, characterized in that: The method comprises the following steps: Step 1: three independent phase current sensors are set in a switched reluctance motor controller, and the switched reluctance motor controller realizes the rotation of the switched reluctance motor by continuously switching the driving current direction; Step 2: Save the instantaneous sampling values ​​of the three-phase current; Step 3: Calculate the weights of the three-phase currents in the current cycle. According to the switch states of the three-phase switch tubes recorded in the ADC interrupt program in the previous cycle, calculate the corresponding weights of the three-phase currents in the current cycle when calculating the power supply current. Step 4: Calculate the estimated power supply current value. Multiply the phase current value obtained in step 2 by the weight value calculated in step 3, and add the results to obtain a preliminary power supply current estimate I est , that is: I est =W a I a +W b I b +W c I c ; Step 5: Perform average filtering on the preliminary power supply current estimate; Step 6: Perform average filtering on the preliminary power supply current estimate obtained in step 4 to obtain the power supply input current I in , predict and calculate the switching state of the three-phase switch tube in the next cycle, specifically, predict and calculate the switching state of the three-phase switch tube in the next cycle according to the actual measured value of the three-phase current in the current cycle.

2. The method for calculating the power supply current of a switched reluctance motor through three-phase current according to claim 1, characterized in that: The step 2 comprises the following steps: In the ADC interrupt program, the instantaneous sampling values ​​of the three-phase current are saved in real time at a frequency of 20kHz; Assume that the three-phase currents are I a ,I b ,I c ; In step 3, the current weights are set to be W a , W b , W c ; The weight value is 1, -1 or 0.

3. The method for calculating the power supply current of a switched reluctance motor through three-phase current according to claim 2, characterized in that: The switch reluctance motor controller switches the directions of the three phase currents through three current chopping circuits, thereby controlling the driving current. The three current chopping circuits have the same structure. The current chopping circuits include power switch 1, power switch 2, diode 1, diode 2 and inductor. The emitter of power switch 1 is connected to the negative electrode of diode 1, the positive electrode of diode 2 is connected to the collector of power switch 2, the collector of power switch 1 is connected to the negative electrode of diode 2, and the emitter of power switch 2 is connected to the positive electrode of diode 1; the two ends of the inductor are respectively connected to the negative electrode of diode 1 and the positive electrode of diode 2; the three current chopping circuits are connected in parallel at the two ends of the power supply.

4. The method for calculating the power supply current of a switched reluctance motor through three-phase current according to claim 3, characterized in that: The step of performing average value filtering on the preliminary power supply current estimation value obtained in step 4 to obtain the power supply input current comprises the following steps: Assume that the time series of a phase current measured is I1, I2, I3, ..., I T , take the number of moving average items as N, and N<T, T is the end time point of current acquisition; Then the moving average value of the current at time t is: Build a predictive model for current flow: Where t = N, N+1, …, N+n; 4≤N≤500; The phase current value and the power supply current value at the next moment are predicted using the current prediction model.

5. The method for calculating the power supply current of a switched reluctance motor through three-phase current according to claim 4, characterized in that: Specifically, predicting and calculating the switch state of the three-phase switch tube in the next cycle according to the actual measured value of the three-phase current in the current cycle includes the following steps: Build a power supply current prediction model: Predict the power supply current and the three phase currents at the next moment through the current prediction model; Get W a , W b and W c The predicted value can then predict the switching states of the power switch 1 and the power switch 2.

6. The method for calculating the power supply current of a switched reluctance motor through three-phase current according to claim 5, characterized in that: The method of predicting the three phase currents at the next moment by using the current prediction model comprises the following steps: The historically measured phase current is used as the input of the circuit prediction model, and the predicted phase current value I at the next moment is output. at+1 ,I bt+1 and I ct+1 ; Set the phase current threshold ΔI s , if the difference between the predicted value of the phase current and the actual measured value is within the threshold range, the predicted phase current value is valid; That is |I bt+1 -I b |≤ΔI s 、|I at+1 -I a |≤ΔI s 、|I ct+1 -I c |≤ΔI s , where I a ,I b ,I c is the actual measured phase current value.

7. The method for calculating the power supply current of a switched reluctance motor through three-phase current according to claim 6, characterized in that: Specifically, predicting and calculating the switch state of the three-phase switch tube in the next cycle according to the actual measured value of the three-phase current in the current cycle also includes the following steps: Set the minimum threshold value I of the phase current min and the highest threshold I max ; Get the three phase currents I of the current cycle at ,I bt ,I ct ; The three phase currents are compared with the lowest threshold value respectively. If they are less than the lowest threshold value, power switch 1 and power switch 2 are set to be turned on at the same time, and the corresponding weight value is 1 at this time; if they are greater than the highest threshold value, power switch 1 and power switch 2 are set to be turned off at the same time, and the corresponding weight value is -1 at this time; if they are between the highest threshold value and the lowest threshold value, power switch 1 and power switch 2 are in one on and one off state, and the weight value is 0 at this time.

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