Switch reluctance motor single current sensor phase current reconstruction method based on model prediction
By using a model-based single-current sensor phase current reconstruction method, the problem of excessive cost and size caused by multiple current sensors in switched reluctance motors is solved, thereby reducing the cost and size of the drive system and improving control accuracy.
Patent Information
- Application Number
- CN202511297436.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-11
- Publication Date
- 2025-11-28
AI Technical Summary
The use of multiple current sensors in switched reluctance motors leads to excessive cost and size of the drive system, and increases the difficulty of current control.
A model-based single-current sensor phase current reconstruction method is adopted. Through an asymmetrical half-bridge power converter and phase shifting method, the three-phase current is reconstructed using a single current sensor, which reduces the number of current sensors and optimizes the sampling time interval.
While maintaining similar control performance, the cost and size of the drive system were reduced, while current ripple was decreased and control accuracy was improved.
Smart Images
Figure CN121036629A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of switched reluctance motor electric current sensor phase current reconstruction, and in particular to a model prediction-based single current sensor phase current reconstruction method for solving the problem of high cost and large volume of a switched reluctance motor drive system caused by multiple current sensors. BACKGROUND
[0002] Switched reluctance motor (SRM) is widely used in traditional mining sectors such as mining machinery, conveying equipment, ventilation equipment, and lifting devices due to its frequent start-stop, high efficiency, strong adaptability, and high reliability. In the current intelligent development of mining, SRM speed regulation system research is the core driver of equipment upgrading and industrial upgrading. In the control mode of SRM, current control can reduce the current peak and torque ripple during commutation. Current chopping control (CCC) achieves control by adjusting the current limit value and the ring width, which is simple to implement. However, the switching frequency of the power converter is not fixed, and the nonlinear change of inductance value will cause current pulsation and spikes during motor commutation. During operation, the inductance, flux linkage, and other parameters of SRM change simultaneously according to the current and mechanical angle. After the saturation of the magnetization curve, the inductance has nonlinear characteristics, making it difficult to accurately obtain motor parameters and increasing the control difficulty. Model predictive current control (MPCC) is a model-based optimal control strategy that handles nonlinear and multivariable systems through rolling optimization. MPC is divided into continuous set model predictive control (CCS-MPCC) and finite set model predictive control (FCS-MPCC). FCS-MPCC is widely used in motor control due to its simplicity, no need for modulation, and good dynamic response. However, MPCC control of SRM requires multiple current sensors, which affects the size and cost of the motor drive system.
[0003] To solve the above problems, a model prediction-based switched reluctance motor single current sensor phase current reconstruction method is proposed, which reconstructs the phase current through a bus single current sensor. This method not only reduces the cost of current sensors but also reduces the size of the switched reluctance motor drive. SUMMARY
[0004] The purpose of the present application is to provide a model prediction-based switched reluctance motor single current sensor phase current reconstruction method that reduces the number of current sensors, lowers the cost and size of the drive system, and reduces current pulsation.
[0005] TECHNICAL SOLUTION
[0006] A model prediction-based switched reluctance motor single current sensor phase current reconstruction method, characterized by at least the following steps:
[0007] Step 1: Get the switch state combination of the power converter through model prediction, and send the switch state combination to the asymmetric half-bridge power converter, while limiting the duty cycle d of the pulse signal.
[0008] Step 2: According to the three-phase conduction state of the asymmetric half-bridge power converter, the A, B, and C three-phase currents are divided into a direct sampling area and a two-phase overlap area.
[0009] Step 3: Modify the sampling points in the two-phase conduction area using the phase shift method, reduce the two sampling time intervals, and eliminate the current reconstruction dead zone.
[0010] Step 4: Sample the three-phase current through phase current reconstruction using a single current sensor. In the direct sampling area, the phase current is obtained directly through the single current sensor, and in the two-phase overlap area, the phase current is obtained through phase current reconstruction.
[0011] Further, the specific method of step 1 includes:
[0012] The drive system of the switched reluctance motor uses an asymmetric half-bridge power converter, and each phase operating mode is divided into excitation mode, freewheeling mode, and demagnetization mode according to the switching state of the upper and lower tubes. The excitation mode is that the upper and lower tubes are simultaneously turned on, at which time the current flows through the current sensor. The freewheeling mode is that the upper tube is turned on and the lower tube is turned off, at which time the current does not flow through the current sensor. The phase in the excitation mode and the freewheeling mode is the conduction phase. The demagnetization mode is that the upper and lower tubes are simultaneously turned off, and the phase current will rapidly decrease in the demagnetization mode, which is called demagnetization current. The switching state of each phase is as follows:
[0013]
[0014] S p is each switching state, V T1 , V T2 is an IGBT. 1 represents the excitation mode, 0 represents the freewheeling mode, and -1 represents the demagnetization mode.
[0015] Through the model predictive current control method, the switching state combination of the output of the power converter is selected, and the specific process is as follows: first, the current i p (k) at the current time is obtained through current reconstruction, the current i p (k+1) at the next time is calculated through the current prediction equation, the current conduction phase is obtained according to the rotor position, the cost function of different switching state combinations is calculated, and the smallest switching state combination is selected as the output, then the duty cycle d of the pulse trigger signal of the output switching state combination is limited, and the limitation requirement is that the duty cycle d is greater than T min / T and less than 1-T min / T, that is, d∈{T min / T, 1-T minFinally, the optimized optimal switch state combination is output to the asymmetric half-bridge power converter. In the above description, the duty cycle d is the ratio of the pulse signal for controlling the power converter switch in a sampling period, T min is the minimum sampling time, and T is the sampling period.
[0016] The cost function is:
[0017]
[0018] where i p * , i q * are the given currents of phases p and q, respectively, i p (k+1), i q (k+1) are the currents of phases p and q at time k+1, and pq∈{AB, BC, CA}.
[0019] Further, the specific method of step 2 includes:
[0020] The phase current is obtained by a single current sensor, and the phase current is A, B, and C three-phase current. According to the acquisition method of the phase current, the phase current can be divided into a direct sampling area and a two-phase overlap area. The current obtained by sampling with a single current sensor is the bus current.
[0021] The direct sampling area is a single-phase conduction area, and only the conduction phase contains current, and the other two phases have no current. The two-phase overlap area is divided into a two-phase simultaneous conduction area and a single-phase conduction area with a demagnetizing current in one phase. This area is referred to as the single-phase conduction area of the two-phase overlap area.
[0022] Taking phases A and B as an example, the interval division is shown in the following table:
[0023]
[0024] Further, the specific method of step 3 includes:
[0025] The sampling points of the two-phase conduction area are modified using the phase shift method. The sampling points are selected as the rising edge or falling edge of the pulse signal. The time interval between the sampling points T1 and T2 is reduced, and the time interval is defined as T d . By reducing T d , the reconstruction error rate is reduced. It should be noted that T d needs to meet the minimum sampling time T min , which is the time required to collect stable bus current.
[0026] The current reconstruction dead zone is eliminated by the phase shift method. In general, the rising edges of the two-phase pulse signals are generated at the same time, and the duty cycles d are different. The rising edge of the selected pulse signal is the sampling point T1, and the purpose is to obtain the bus current when the two-phase pulse signals act simultaneously. The falling edge of the pulse signal of the phase with smaller duty cycle d is the sampling point T2, and the purpose is to obtain the bus current when the pulse signal with larger duty cycle d acts alone. When the time of the pulse signal with larger duty cycle d acting alone is less than the minimum sampling time T min , the current sensor cannot obtain the bus current when the pulse signal acts alone, which will lead to current reconstruction failure.
[0027] The specific phase shift method is: in the two-phase conduction region, the rising edge of the pulse signal of the phase with smaller duty cycle d is right shifted by T min , and at this time, the time difference between the rising edges of the two-phase pulse signals is the sampling time T v , that is, T v =T min , and the rising edges of the two-phase pulse signals are selected as the first sampling point T1 and the second sampling point T2 respectively. Since T v =T min , the bus current when the pulse signal of one phase acts alone can be obtained at the sampling point T1, and the sampling time T v available at the sampling point T2 is the pulse action time, which is greater than T min , so the bus current when the two-phase pulse signals act simultaneously can be obtained, which eliminates the current reconstruction dead zone and reduces the time interval T d of the two samplings, thereby reducing the reconstruction error.
[0028] Further, the specific method in step 4 includes:
[0029] The three-phase current is sampled by using the phase current reconstruction through the single current sensor. In the direct sampling region, the bus current is obtained by the single current sensor, and at this time, the obtained bus current is the conduction phase current, which can be directly sampled and obtained.
[0030] In the two-phase overlap region, the bus current obtained by the single current sensor is the sum of the two-phase currents, so the phase current reconstruction is needed to obtain each phase current, and in the two-phase conduction region, the phase shift method of step 3 is used to reduce the sampling interval and eliminate the reconstruction dead zone. In the single-phase conduction region in the overlap region, due to the existence of the demagnetizing current, the bus current will still be in the state of the sum of two phases, but due to the limitation of the pulse signal duty cycle d, the other phase will be between the excitation mode and the freewheeling mode, so the conduction phase current can be reconstructed by two samplings.
[0031] In the two-phase conduction region in the two-phase overlap region after phase shift, the phase current reconstruction step is:
[0032] Step 4.1
[0033] At the sampling point T1, one phase is in the excitation mode and one phase is in the freewheeling mode, the primary bus current is collected by the single current sensor. Since the current of one phase cannot be collected at T1 because the phase is in the freewheeling state, the collected bus current is only the current of the phase in the excitation mode. The collected bus current is defined as i bus1 .
[0034] Step 4.2
[0035] At the sampling point T2, both phases are in the excitation mode, the primary bus current is collected by the single current sensor. Since both phases are in the excitation mode at T2, the collected bus current is the sum of the currents of the two phases. The collected bus current is defined as i bus2 .
[0036] Step 4.3
[0037] The bus current obtained in step 4.1 is used to obtain the current of one phase. The bus current i bus1 collected at T1 is subtracted from the bus current i bus2 collected at T2, and the current of the other phase is obtained.
[0038] In the single-phase conduction interval of the overlap interval, the phase current reconstruction steps are the same as those in the two-phase conduction interval. At the sampling point T1, the conduction phase is in the excitation mode, the primary bus current i bus1 is collected, and the bus current i bus1 is the sum of the currents of the two phases. At the sampling point T2, the conduction phase is in the freewheeling mode, the primary bus current i bus2 is collected, and the bus current i bus2 is the demagnetization current. Since the time interval between the two sampling times is very short, the demagnetization current is considered to be constant, and thus the bus current i bus1 collected at the first time is subtracted from the bus current i bus2 collected at the second time, and the current of the conduction phase is obtained.
[0039] Advantages
[0040] The three current sensors of the traditional three-phase switched reluctance motor can increase the cost and size of the switched reluctance motor drive system. Compared with the traditional three current sensors, a single current sensor phase current reconstruction method based on model prediction for a switched reluctance motor reduces two current sensors, reduces the cost and size of the drive system, and has a similar control effect. BRIEF DESCRIPTION OF DRAWINGS
[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.
[0042] Figure 1 It is a general control block diagram of the present application.
[0043] Figure 2 It is three working modes of the asymmetric half-bridge power converter of each phase of the present application according to the switching state of upper and lower tubes.
[0044] (a) is the excitation mode.
[0045] (b) is the freewheeling mode.
[0046] (c) is the demagnetization mode.
[0047] Figure 3 It is a current partition diagram of phase A and phase B of the present application.
[0048] Figure 4 It is a current waveform and sampling point diagram of two-phase conduction area before and after phase shifting of the present application.
[0049] (a) is before phase shifting
[0050] (b) is after phase shifting
[0051] Figure 5 It is a phase current and bus current waveform diagram of two-phase conduction area after phase shifting of the present application.
[0052] Figure 6 It is a phase current and bus current waveform diagram of single-phase conduction area of two-phase overlap area of the present application.
[0053] Figure 7 It is a comparison diagram of three current sensors measured current and reconstructed three-phase current when the rotating speed is 100 rpm. Specific implementation
[0054] The present application will be further described below in combination with the embodiments in the drawings, which are exemplary and intended to explain the present application, and cannot be understood as limiting the present application. The motor used in the example is a 5kW three-phase 12 / 8 switched reluctance motor.
[0055] As Figure 1 shown, the present application proposes a single current sensor phase current reconstruction method for switched reluctance motor based on model prediction, in which ω, ω ref is the rotating speed feedback and the given rotating speed, and the given current i is obtained after PI control.p * i bus The bus voltage is θ, the rotor position is i p (k) represents the current at time k in phase p. This invention is characterized by including at least the following steps:
[0056] Step 1: Obtain the switching state combination of the power converter through model prediction, and send the switching state combination to the asymmetric half-bridge power converter, while limiting the duty cycle d of the pulse signal.
[0057] like Figure 2 As shown, the drive system of the switched reluctance motor uses an asymmetrical half-bridge power converter. The operating modes of each phase are divided into three types based on the switching states of the upper and lower transistors: excitation mode, freewheeling mode, and demagnetizing mode. In excitation mode, both transistors are on simultaneously, and current flows through the current sensor. In freewheeling mode, the upper transistor is on and the lower transistor is off, and current does not flow through the current sensor. The phases in excitation mode and freewheeling mode are the conducting phases. In demagnetizing mode, both transistors are off simultaneously. In demagnetizing mode, the current in this phase drops rapidly, and this is called the demagnetizing current. (See diagram V...) T1 V T2 For IGBTs, D1 and D2 are freewheeling diodes, U dc This is the bus voltage.
[0058] The switching states of each phase are as follows:
[0059]
[0060] S p V represents the switching states of each device. T1 V T2 This is an IGBT. 1 represents excitation mode, 0 represents freewheeling mode, and -1 represents demagnetization mode.
[0061] The switching state combination of the power converter output is selected using a model-predictive current control method. The specific process is as follows: First, the current i at the current time is obtained through current reconstruction. p (k), the current i at the next moment is calculated by the current prediction equation. p (k+1), and simultaneously obtain the current conducting phase based on the rotor position. Then, calculate the cost function of different switching state combinations, select the switching state group with the smallest cost function as the output, and then limit the duty cycle d of the pulse trigger signal of the output switching state combination. The requirement is that the duty cycle d is greater than T. min / T, less than 1-T min / T, that is, d∈{T} min / T, 1-T min / T}. Finally, the optimized combination of switching states is output to the asymmetric half-bridge power converter. In the above description, the duty cycle d is the proportion of the pulse signal controlling the power converter switching within one sampling period, and T min The minimum sampling time is T, and the sampling period is T.
[0062] The cost function is:
[0063]
[0064] In the formula i p * i q * Given currents for phases p and q respectively, i p (k+1), i q (k+1) represents the phase currents pq at time k+1, where pq∈{AB,BC,CA}.
[0065] Step 2: Based on the three-phase conduction state of the asymmetrical half-bridge power converter, divide the three-phase currents A, B, and C into a direct sampling region and a two-phase overlap region.
[0066] The phase current is obtained by a single current sensor. The phase current consists of three phases: A, B, and C. Based on the method of obtaining the phase current, the phase current can be divided into a direct sampling area and a two-phase overlap area. The current obtained by sampling through a single current sensor is the bus current.
[0067] The direct sampling region is a single-phase conduction region, in which only the conducting phase contains current, while the other two phases have no current. The two-phase overlap region is further divided into a region where both phases conduct simultaneously and a region where one phase is conducting and the other phase contains demagnetizing current; this region is called the single-phase conduction region of the two-phase overlap region. The phase current partitioning of phases A and B is as follows: Figure 3 As shown.
[0068] Taking phases A and B as examples, the interval division is shown in the table below:
[0069]
[0070] Step 3: Use the phase-shifting method to modify the sampling points in the two-phase conduction region, reduce the time interval between two samplings, and eliminate the current reconstruction dead zone.
[0071] Taking phases A and B as an example, the sampling points in the conduction regions of phases A and B are modified using a phase-shifting method. The sampling points are selected as the rising or falling edge of the pulse signal. In actual sampling, the sampling points need to be delayed by a certain time from the rising or falling edge to ensure accurate sampling. The time interval between sampling points T1 and T2 is reduced, and this time interval is defined as T. d By reducing T d To reduce the reconstruction error rate. Note that T... dMinimum sampling time T must be met min The minimum sampling time is the time required to acquire a stable bus current.
[0072] The current reconstruction dead zone is eliminated by phase shifting. The current reconstruction dead zone is as follows: Figure 4 As shown in (a), the duration of the A-phase pulse signal acting alone is less than the minimum sampling time T. min That is, the sampling time is less than T. min If the current sensor cannot obtain the bus current at this time, it will lead to current reconstruction failure.
[0073] The specific phase shifting method is as shown in Figure 4(b), where Δi A The reconstruction error is T, where T is the sampling period and S is the time interval. A S B In the power converter switching state, during the two-phase conduction region, the rising edge of the pulse signal of phase B with the smaller duty cycle d is shifted right by T. min At this point, the available sampling time T v T is the time difference between the rising edges of the two phase pulse signals A and B. v =T min The rising edges of the A and B phase pulse signals are selected as the first sampling point T1 and the second sampling point T2, respectively. Since T... v =T min Therefore, at sampling point T1, the bus current under the action of a single-phase pulse signal can be obtained, while at sampling point T2, the available sampling time T v Greater than T min Therefore, the bus current under the action of two-phase pulse signals can be obtained, thus eliminating the current reconstruction dead zone and reducing the time interval T between the two samplings. d This reduces Δi A .
[0074] Step 4: Sample the three-phase current using a single current sensor to reconstruct the phase current.
[0075] In the direct sampling region, the bus current is obtained through a single current sensor. The obtained bus current is the current of the conducting phase and can be directly sampled.
[0076] In the two-phase overlap region, the bus current acquired by the single current sensor is the sum of the two-phase currents. Therefore, phase current reconstruction is required to obtain the current of each phase. In the two-phase conduction region, the phase shifting method in step 3 needs to be used to reduce the sampling interval and eliminate the reconstruction dead zone. In the single-phase conduction region of the overlap region, due to the presence of demagnetizing current, the bus current will still be in the state of the sum of the two phases. However, due to the limitation of the pulse signal duty cycle d, the other phase will always be between the excitation mode and the freewheeling mode. Therefore, the conducting phase current can also be reconstructed from two samples.
[0077] In the two-phase overlap region, taking the conduction of phases A and B as an example, as follows: Figure 5 As shown, in the phase-shifted simultaneous conduction regions of phases A and B, the phase current reconstruction steps are as follows:
[0078] Step 4.1
[0079] At time T1, when phase A is in excitation mode and phase B is in freewheeling mode, the bus current is collected by a single current sensor. Since phase B is in freewheeling mode at time T1, the sensor cannot collect phase B current; therefore, the collected bus current is only the current of phase A in excitation mode. The collected bus current is defined as i. bus1 .
[0080] Step 4.2
[0081] At time T2, when both phases A and B are in excitation mode, the primary bus current is collected using a single current sensor. Since both phases are in excitation mode at time T2, the collected bus current is the sum of the two phase currents. The collected bus current is i. bus2 .
[0082] Step 4.3
[0083] The A-phase current can be obtained from the bus current obtained in step 4.1. The i-phase current acquired at time T1 can then be used as the basis for determining the phase current. bus1 i acquired at time T2 bus2 Subtracting the two phases gives the current in phase B. The formula is:
[0084]
[0085] In the formula i A i B These are the currents of phases A and B, respectively.
[0086] like Figure 6 As shown, in the single-phase conduction section of the overlapping interval, the phase current reconstruction steps are the same as those in the two-phase conduction section. At time T1, when phase B is in excitation mode, the primary bus current i is collected. bus1 At this time, the bus current i bus1 The currents of phases A and B are combined. At time T2, when phase B is in freewheeling mode, the primary bus current i is sampled. bus2 At this time, the bus current i bus2 This represents the demagnetizing current of phase A. Since the time interval between the two samplings is very short, the demagnetizing current is assumed to remain constant; therefore, the bus current i from the first sampling is used. bus1 Subtract the bus current i from the second data collection bus2 The B-phase current can then be obtained. The formula is:
[0087]
[0088] By Figure 7 The specific effect of the single current sensor phase current reconstruction method can be seen in Fig. e max The maximum current reconstruction error is A, and it can be seen that the current pulsation is smaller after current reconstruction; the current reconstruction error of B and C phases is smaller, and the maximum reconstruction errors are 0.5 A for B phase and 0.3 A for C phase.
[0089] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that; the technical solutions recorded in the foregoing embodiments can be modified, or part or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the present application examples.
Claims
1. A model prediction based switched reluctance motor single current sensor phase current reconstruction method, characterized in that, At least the following steps are included: Step 1: Obtain the switching state combination of the power converter through model prediction, and send the on state combination to the asymmetric half-bridge power converter, while limiting the duty cycle d of the pulse signal; Step 2: Based on the three-phase conduction state of the asymmetrical half-bridge power converter, divide the three-phase currents A, B, and C into a direct sampling region and a two-phase overlap region; Step 3: Use the phase-shifting method to modify the sampling points in the two-phase conduction region, reduce the time interval between two samplings, and eliminate the current reconstruction dead zone; Step 4: Sample the three-phase current using a single current sensor to reconstruct the phase current. In the direct sampling region, the phase current is obtained directly through the single current sensor, and in the two-phase overlap region, the phase current is obtained through phase current reconstruction.
2. A model prediction based switched reluctance motor single current sensor phase current reconstruction method according to claim 1, the main features of which comprise: The specific methods in step 1 include: The drive system of the switched reluctance motor uses an asymmetrical half-bridge power converter. The operating modes of each phase are divided into three types based on the switching states of the upper and lower transistors: excitation mode, freewheeling mode, and demagnetizing mode. In excitation mode, both transistors are simultaneously on, and current flows through the current sensor. In freewheeling mode, the upper transistor is on and the lower transistor is off, and current does not flow through the current sensor. The phases in excitation and freewheeling modes are conducting phases. In demagnetizing mode, both transistors are simultaneously off. In demagnetizing mode, the current in that phase drops rapidly, and this is called the demagnetizing current. The switching states of each phase are as follows: S p For each switch state, V T1 , V T2 is the IGBT; 1 represents the excitation mode, 0 represents the freewheeling mode, and -1 represents the demagnetization mode; The method of model predictive current control selects a switch state combination of the output of the power converter, and the specific process is as follows: first, the current i p (k) at the current moment is obtained through current reconstruction, the current i p (k+1) at the next moment is calculated through a current prediction equation, and then the current conduction phase is obtained according to the rotor position; then, the cost functions of different switch state combinations are calculated, and the switch state combination with the minimum cost is selected as the output; then, the duty cycle d of the pulse trigger signal of the switch state combination is limited, and the limitation requirement is that the duty cycle d is greater than T min / T and less than 1-T min / T, that is, d∈{T min / T, 1-T min / T}; finally, the optimized optimal switch state combination is output to the asymmetric half-bridge power converter; in the above description, the duty cycle d is the ratio of the pulse signal for controlling the switch of the power converter in a sampling period, T min is the minimum sampling time, and T is the sampling period. The cost function is: where i p * , i q * are given currents in phases p, q, respectively, i p (k+1), i q (k+1) are currents in phases p, q at time k+1, respectively, pq∈{AB, BC, CA}.
3. A model prediction based method for reconstructing phase currents in a switched reluctance motor using a single current sensor, according to claim 1, the method comprising: The specific methods in step 2 include: The phase current is obtained by a single current sensor. The phase current consists of three phases: A, B, and C. Based on the method of obtaining the phase current, the phase current can be divided into a direct sampling area and a two-phase overlap area. The current obtained by sampling through a single current sensor is the bus current. The direct sampling region is a single-phase conduction region, in which only the conducting phase contains current, while the other two phases have no current; the two-phase overlap region is further divided into the two-phase simultaneous conduction region and the region where one phase is conducting and the other phase contains demagnetizing current. This region is called the single-phase conduction region of the two-phase overlap region. Taking phases A and B as examples, the interval division is shown in the table below:
4. A model prediction based switched reluctance motor single current sensor phase current reconstruction method according to claim 1, Its main features include: The specific methods in step 3 include: The sampling points of the two-phase conduction region are modified using a phase shift method, the sampling points are selected as rising edges or falling edges of the pulse signal, the time interval of the sampling points T1 and T2 is reduced, and the time interval is defined as T d , the reconstruction error rate is reduced by reducing T d ; it should be noted that T d needs to meet the minimum sampling time T min , the minimum sampling time is the time required to collect the stable bus current; The current reconstruction dead zone is eliminated by the phase shift method, and the current reconstruction dead zone is: in general, the rising edges of the two-phase pulse signals are generated at the same time, and the duty cycles d are different, the rising edge of the selected pulse signal is the sampling point T1, and the purpose is to obtain the bus current when the two-phase pulse signals act at the same time; the falling edge of the pulse signal of the phase with smaller duty cycle d is the sampling point T2, and the purpose is to obtain the bus current when the pulse signal with larger duty cycle d acts alone; when the time of the pulse signal with larger duty cycle d acting alone is less than the minimum sampling time T min , the current sensor cannot obtain the bus current when the pulse signal acts alone, which will lead to the failure of current reconstruction; The specific phase shifting method is as follows: In the two-phase conduction region, the rising edge of the pulse signal of the phase with the smaller duty cycle d is shifted to the right by T. min At this time, the time difference between the rising edges of the two phase pulse signals is the time T available for sampling. v That is, T v =T min The rising edges of the two phase pulse signals are selected as the first sampling point T1 and the second sampling point T2, respectively; since T v =T min Therefore, at sampling point T1, the bus current under the action of a single phase pulse signal can be obtained, while at sampling point T2, the available sampling time T is... v The pulse duration is greater than T. min Therefore, the bus current when two-phase pulse signals act simultaneously can be obtained, thus eliminating the current reconstruction dead zone and reducing the time interval T between the two samplings. d This reduces reconstruction errors.
5. A model prediction based switched reluctance motor single current sensor phase current reconstruction method according to claim 1, Its main features include: The specific methods in step 4 include: Three-phase current is sampled by reconstructing phase current using a single current sensor; in the direct sampling region, the bus current is obtained by a single current sensor, and the obtained bus current is the conducting phase current, which can be directly sampled. In the two-phase overlap region, the bus current obtained by the single current sensor is the sum of the two-phase currents. Therefore, phase current reconstruction is required to obtain the current of each phase. In the two-phase conduction region, the phase shifting method in step 3 needs to be used to reduce the sampling interval and eliminate the reconstruction dead zone. In the single-phase conduction region of the overlap region, due to the presence of demagnetizing current, the bus current will still be in the state of the sum of the two phases. However, due to the limitation of the pulse signal duty cycle d, the other phase will definitely be between the excitation mode and the freewheeling mode. Therefore, the conducting phase current can also be reconstructed by two samplings. In the two-phase conduction region of the overlapping two-phase interval after phase shift, the phase current reconstruction steps are as follows: Step 4.1 At the sampling point T1, one phase is in the excitation mode and one phase is in the freewheeling mode. The primary bus current is collected by the single current sensor. Since one phase is in the freewheeling state at the T1, the sensor cannot collect the current of the phase, and thus the collected bus current is only the current of the phase in the excitation mode. The collected bus current is defined as i bus1 ; Step 4.2 At the sampling point T2, at this time, both phases are in the excitation mode, and the primary bus current is collected by the single current sensor. Since both phases are in the excitation mode at T2, the collected bus current is the sum of the two-phase currents; the collected bus current is defined as i bus2 ; Step 4.3 By the bus current obtained in step 4.1, that is, one phase current; subtracting i bus1 T2 time collected, that is, another phase current; bus2 T2 time collected, that is, another phase current; In the single-phase conduction interval of the overlapping interval, the phase current reconstruction step is the same as the phase current reconstruction mode of the two-phase conduction interval. At the sampling point T1, the conduction phase is in the excitation mode at this time, the primary bus current i bus1 is collected, the bus current i bus1 is the sum of the two-phase currents; at the sampling point T2, the conduction phase is in the freewheeling mode at this time, the primary bus current i bus2 is collected, the bus current i bus2 is the demagnetizing current; since the time interval between the two sampling times is very short, the demagnetizing current is considered to be constant, so the first collected bus current i bus1 is subtracted from the second collected bus current i bus2 , and the conduction phase current is obtained.