Integrated control method of high-speed switched reluctance motor driving system

Abstract

The invention discloses an integrated control method of a high-speed switched reluctance motor driving system, the driving system comprises a voltage source converter (VSC), each phase of a three-phase alternating current power supply is respectively connected with a power supply input end of the VSC through a resistor # imgabs0 # and an inductor # imgabs1 # in sequence, a switched reluctance motor is driven through an SRM driver, and the SRM driver is connected with the voltage source converter; according to the method, a required voltage vector (namely P-DBC) is calculated by establishing an instantaneous power model and combining assumption that a driving system finally achieves an expected behavior in each control period, so that the driving voltage of an SRM driver is obtained, that is, a VSC is directly provided through instantaneous active power control of the P-DBC, direct connection of a power supply is established between the VSC and the SRM, and the driving voltage of the SRM driver is obtained. And the whole system is controlled by controlling instantaneous power flow.

Description

Technical Field

[0001] The present invention relates to the technical field of switched reluctance motors, and more specifically to an integrated control method for a high-speed switched reluctance motor drive system. Background Art

[0002] The switched reluctance motor has a simple structure, no windings on the rotor, and the motor itself has high mechanical strength, so it can be used for frequent starting and stopping or ultra-high-speed operation.

[0003] In the prior art, such as Figure 1a As shown in FIG. 1 , the switched reluctance motor (SRM) uses a diode bridge rectifier (DBR) to drive the SRM drive; however, although the use of a diode bridge rectifier (DBR) reduces the cost of the drive system, it will induce a large amount of reactive power and current harmonics in the power grid that are detrimental to the power quality, and even worse, the reactive power is greater than the active power, and the uncontrollable DC bus voltage of the diode bridge rectifier (DBR) is easily affected by the operating conditions of the SRM drive; therefore, some people use a DC power supply to drive the SRM drive, such as Figure 1b As shown, the above problem is solved in this way, but the switched reluctance motor drive system obtained by this method is expensive.

[0004] In addition, in the existing switched reluctance motor drive system, such as Figure 2 As shown, the front-end converter and the back-end SRM driver each have independent modules for control methods. The control method of the front-end converter is to adjust the grid-side PQ, and the control method of the SRM driver is to adjust the speed of the switched reluctance motor, which makes the structure of the switched reluctance motor drive system more complicated.

[0005] In view of this, the applicant conducted in-depth research on this basis, which led to the emergence of this case. Summary of the invention

[0006] The object of the present invention is to provide an integrated control method for a high-speed switched reluctance motor drive system, which can achieve satisfactory power quality and energy feedback, has low cost, and simplifies the switched reluctance motor drive system.

[0007] To achieve the above object, the solution of the present invention is: An integrated control method for a high-speed switched reluctance motor drive system, characterized in that the drive system includes a voltage source converter, each phase of a three-phase AC power supply is sequentially connected through a resistor and inductance Connecting the power input terminal of the voltage source converter, the switched reluctance motor is driven by an SRM driver, and the SRM driver is interconnected with the voltage source converter; comprising the following steps: S1. Establish the instantaneous power model in the stationary α and β coordinate planes as follows: (1), where is the instantaneous active power, is the instantaneous reactive power, yes The grid voltage in the coordinate system Quantity, yes The grid voltage in the coordinate system Quantity, yes Grid-side current in the coordinate system; and The relationship expression is: (2), In the formula, represents the angular frequency of the grid-side voltage, where , Indicates the grid frequency; The voltage source conversion model in the stationary α, β coordinate plane is established as follows, (3), In the formula, yes The grid-side current in the coordinate system is: yes The grid voltage in the coordinate system is: Indicates the grid-side inductance value, Indicates the grid side resistance value, yes The voltage of the voltage source converter in the coordinate system; Substituting expressions (2) and (3) into the instantaneous power model, the following expressions are obtained: (4), S2. Perform backward Euler discretization on expression (4) in step S1 and convert it into the following expression: (5), In expression (5), express The variable value at the time, where is a general term for variables, which can represent , or ; express The variable value at the time, represents the control cycle, yes The voltage of the converter at time k in the coordinate system Quantity, yes The voltage of the converter at time k in the coordinate system Quantity, yes The grid voltage at time k in the coordinate system Quantity, yes The grid voltage at time k in the coordinate system Quantity, ] is the grid-side active power at time k+1, is the grid-side reactive power at time k+1; S3, using the nominal value of the grid-side inductance And the nominal value of the grid side resistance Participate in the prediction calculation respectively, the instantaneous power model is as follows: (6), In the following table, "no" represents the nominal value. and are interference parameters; S4. Set the deadbeat control as follows: Assuming that the drive system achieves the expected behavior at the end of each control cycle, the required voltage vector is calculated as follows: and , and substitute it into expression (6), we get the following expression: , In the formula, and is The estimated disturbance has been obtained in the interval, yes The grid voltage at time k in the coordinate system; represents the expected instantaneous active power required by the motor side, where = , is the torque reference, torque reference Through the speed proportional-integral controller output of the switched reluctance motor, is the angular velocity of the switched reluctance motor, and the angular velocity Calculated in the position estimator by the feedback encoder signal on the motor shaft from the switched reluctance motor; Indicates reactive power reference; S5: The voltage vector calculated in step S4 is output and input to the voltage source converter through a conventional SVPWM module.

[0008] The position between each two phases of the switched reluctance motor is determined according to the Power on in sequence, is the position of the switched reluctance motor, the position A feedback encoder signal from the motor shaft of the switched reluctance motor is calculated on a position estimator.

[0009] Add step S3-1 between completing step S3 and step S4; S3-1. Assume that in expression (6) and The value of is constant in each sampling interval, and the instantaneous power model is as follows, (6-1), In the formula, Represents a set of defined variables, including 4 variables; , represents the observer matrix gain, represents the active disturbance at time k+1, represents the reactive disturbance at time k+1, represents the active power estimation at time k, represents the active power estimation at time k+1, represents the reactive power estimation at time k, represents the reactive power estimation at time k+1; is a mathematical matrix, ; in, , , and According to expression (6-1), the instantaneous power at the next moment is calculated, where: and Respectively Obtained within the range of and Obtained from the last interval, calculated at the initial time k=0 hour = =0.

[0010] After adopting the above method, the present invention has the following beneficial effects: the present invention establishes a direct power supply connection between the voltage source converter and the SRM driver, thereby regarding the voltage source converter and the SRM driver as a whole, and the switched reluctance motor drive system is more simplified and has a lower cost; and the present invention controls the instantaneous active power flowing to the motor side, thereby simultaneously realizing controllable speed, energy feedback, a grid-side power factor close to unity, and low grid-side current distortion, and combines predictive deadbeat control with a disturbance observer to ensure that the instantaneous active power and the instantaneous reactive power simultaneously track their respective reference values ​​without steady-state errors, thereby achieving satisfactory power quality and energy feedback. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1a Schematic diagram of driving a switched reluctance motor based on a diode bridge rectifier.

[0012] Figure 1b Schematic diagram of driving a switched reluctance motor based on a DC power supply.

[0013] Figure 2 This is a schematic diagram of independent control in an existing drive system.

[0014] Figure 3 Schematic diagram of the topological structure of the drive system.

[0015] Figure 4 This is a block diagram of the integrated control method for the drive system. DETAILED DESCRIPTION

[0016] In order to further explain the technical solution of the present invention, the present invention is described in detail below through specific embodiments.

[0017] The present invention provides an integrated control method for a high-speed switched reluctance motor drive system. Figure 3-4 As shown, the drive system is powered by a conventional three-phase AC power supply, including a voltage source converter (VSC) and an asymmetric half-bridge controller (AHBC). The voltage source converter (VSC) and the asymmetric half-bridge controller (AHBC) are electrically connected to each other in a conventional manner. The asymmetric half-bridge controller here can adopt a conventional half-bridge controller, and the voltage source converter can adopt a conventional three-phase voltage type rectifier. Each phase of the three-phase AC power supply is sequentially connected through a resistor. and inductance Connect to the corresponding power input terminal of the voltage source converter; in this embodiment, the above-mentioned AHBC is an SRM driver, wherein the SRM driver is a conventional driver for driving a switched reluctance motor (SRM), and is connected to the switched reluctance motor (SRM) in a conventional manner.

[0018] The integrated control method provided in this embodiment is based on the topological structure of the above-mentioned drive system to drive the high-speed SRM, and includes the following steps: S1. Establish the instantaneous power model in the stationary α and β coordinate planes as follows: (1) In the formula, is the instantaneous active power, is the instantaneous reactive power, , yes The grid voltage in the coordinate system Quantity, yes Grid-side current in the coordinate system; and The relationship expression is: (2), where represents the angular frequency of the grid-side voltage, where , Indicates the grid frequency; The voltage source conversion model in the stationary α and β coordinate planes is established as follows: (3), In the formula, yes The grid-side current in the coordinate system is: yes The grid voltage in the coordinate system is: Indicates the grid-side inductance value, Indicates the grid side resistance value, yes The voltage of the voltage source converter in the coordinate system; Substituting expressions (2) and (3) into the instantaneous power model, that is, substituting expressions (2) and (3) into expression (1), the following expressions are obtained: (4); S2. Perform backward Euler discretization on expression (4) in step S1 and convert it into the following expression: (5), In expression (5), represents the control cycle, yes The voltage of the converter at time k in the coordinate system Quantity, yes The voltage of the converter at time k in the coordinate system Quantity, yes The grid voltage at time k in the coordinate system Quantity, yes The grid voltage at time k in the coordinate system Quantity, ] is the grid-side active power at time k+1, is the grid-side reactive power at time k+1; express The variable value at the time, express The variable value at the moment, here is a general term for variables that can represent , and .

[0019] It should be noted that when the inductor and resistor When the actual values ​​of are substituted into the above expression (5), the expression is established. However, due to the inductance and resistor These are all unknown values, and the values ​​measured by the measuring instruments have errors. Moreover, these values ​​will also change with environmental factors such as temperature. Therefore, the values ​​of these parameters are uncertain. and resistor In fact, they are all nominal values, that is, the inductance and resistor All are involved in the prediction calculation, and the above uncertainty parameters are regarded as dynamic disturbances.

[0020] S3, using the nominal value of the grid-side inductance And the nominal value of the grid side resistance They are involved in the prediction calculation respectively, and they are substituted into expression (5) to obtain the instantaneous power model as follows: (6), In the following table, "no" represents the nominal value. and are interference parameters; and is The estimated disturbance has been obtained in the interval.

[0021] S4, assuming that in the above expression (6) and The value of is constant in each sampling interval, so the instantaneous power model at the next moment (k+1 moment) is as follows: (6-1), In the formula, and is The estimated disturbance has been obtained in the interval, ; Represents a set of defined variables, including These 4 variables; is the active disturbance at time k+1, is the reactive disturbance at time k+1, is the active power estimate at time k, is the active power estimate at time k+1, is the reactive power estimate at time k, is the reactive power estimate at time k+1, Meaning, is an artificially defined observer matrix to simplify the formula; , are the observer matrix gains, which are parameters set manually in the conventional way.

[0022] S5, deadbeat control (P-DBC) is as follows: Assuming that the drive system achieves the expected behavior at the end of each control cycle, the required voltage vector is calculated as follows, let and , substituting into expression (6), we get the following expression: , In the formula, Indicates the expected instantaneous active power required on the motor side; Represents reactive power reference, which is a parameter given manually in a conventional manner; in, = , where is the torque reference of the SRM, and Output through a conventional speed PI controller; is the location of the SRM, is the angular velocity of SRM, the position of SRM and angular velocity The feedback encoder signal on the motor shaft of the SRM is calculated in the position estimator. It is a common practice to install the feedback encoder and the position estimator on the motor separately. and angular velocity The calculation of is also an existing conventional technology, so it will not be described in detail; in this embodiment, the drive system adopts predictive deadbeat control (P-DBC) with a disturbance observer.

[0023] It should be noted that the deadbeat control (P-DBC) mentioned above refers to the calculation of the required variables by assuming that the system reaches the expected behavior at the end of each control cycle; wherein, the P-DBC with disturbance observer is used to make the input active power p and reactive power q follow and , in unit PF .

[0024] S6: The voltage vector calculated in step S5 is output and input to the voltage source converter through a conventional SVPWM module.

[0025] It is worth mentioning that in this embodiment, the error caused by the mismatched parameters is considered to be the expression for the converter voltage required for correction (i.e., the expression ) disturbances, thereby providing robust control.

[0026] In addition, in the present invention, taking instant k as an example, the implementation method of P-DBC with disturbance observer is described as follows.

[0027] First, based on the measured and and , and then use the above values ​​to update and Substituting into expression (7), we can calculate the required converter voltage , the converter voltage is the voltage of the SRM driver in the drive system. and Measured in the usual way.

[0028] Among them, the above and They are manually set values. When the set value is changed and Will be updated.

[0029] The above and They are calculated by the following formulas: .

[0030] Further speaking, , , and According to the above expression (6-1), the prediction is carried out respectively, and the relevant variable data is brought into the expression (6-1) to obtain the power for the next moment (i.e., moment k+1); wherein, and Respectively In the range of and The acquisition of is an iterative process, and the result of the previous moment can be called; it is worth mentioning that due to and is obtained from the last interval, so at the initial moment, that is, when k=0, calculate hour = =0; the above steps are the process of model predictive control to make the model more accurate.

[0031] It should be noted that if Figure 4 As shown, the parameters of the improved part of the present invention can be obtained by using conventional switched reluctance motor drive technology, for example, the conduction angle and the cut-off angle are respectively input into the overcurrent protection module, and the overcurrent protection output , , and Another example is the output of a three-phase AC power supply and .

[0032] Furthermore, the conduction angle and the cut-off angle of the phase winding form a predefined lookup table respectively, so as to use different conduction angles and cut-off angles at different speeds, wherein the conduction angle and the cut-off angle are respectively determined in advance by the following drive system through experiments.

[0033] In the present invention, since the SRM driver can be regarded as the load of the VSC, the output active power of the VSC (denoted as ) is the active power consumed by the DC bus capacitor (denoted as ) and the active power, the power consumed by the SRM drive (denoted as ),Right now The power flow process of the driving system of the present invention is specifically described as follows.

[0034] Assumptions > ,because , the DC bus voltage increases, and then because the DC bus voltage is applied to the winding terminals in each conduction region, Increase, The increase makes Reduce, Continue to increase until ,Right now .

[0035] Assumptions < ,because , the DC bus voltage decreases, making Reduce, so that gradually approaches zero, hour, Stop decreasing.

[0036] From this we can see that Adjustable , that is, constant Indicates constant Therefore, in the present invention, the speed of the SRM is adjusted by directly controlling the active power flowing to the motor side, and the above-mentioned predictive deadbeat control can ensure that the active power flowing to the motor side follows the aforementioned reference , thereby realizing energy feedback and feeding back the excess active power to the grid; in addition, this embodiment sets , in order to improve the grid-side PF and current harmonics.

[0037] In the integrated control method of the present invention, a power control method is proposed to simultaneously manage the voltage source converter at the front end and the switched reluctance motor at the back end so that a direct power connection is established between the voltage source converter and the switched reluctance motor, that is, the voltage source converter and the SRM drive are regarded as a whole to simplify the system, and the P-DBC with a disturbance observer can ensure that the active power and the reactive power simultaneously track their reference values ​​without steady-state errors, thereby achieving satisfactory SRM control performance. Specifically, the P-DBC uses inaccurate system parameters in the calculation, and the error between the reference power and the actual power is considered as an interference term, and the feedforward effect of the error ensures that the estimated interference term is added to the calculated voltage reference, thereby providing stable control. Therefore, the errors caused by the mismatched nominal values ​​and changes in the actual values ​​of the parameters can be compensated by adding additional terms to the expression of the desired voltage vector.

[0038] The above description is only a preferred embodiment of the present embodiment, and all equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. An integrated control method for a high-speed switched reluctance motor drive system, characterized in that: The drive system includes a voltage source converter, each phase of the three-phase AC power supply is sequentially connected through a resistor and inductance Connecting the power input terminal of the voltage source converter, the switched reluctance motor is driven by an SRM driver, and the SRM driver is interconnected with the voltage source converter; comprising the following steps: S1. Establish the instantaneous power model in the stationary α and β coordinate planes as follows: (1), where is the instantaneous active power, is the instantaneous reactive power, yes The grid voltage in the coordinate system Quantity, yes The grid voltage in the coordinate system Quantity, yes Grid-side current in the coordinate system; and The relationship expression is: （2）， In the formula, represents the angular frequency of the grid-side voltage, where , Indicates the grid frequency; The voltage source conversion model in the stationary α, β coordinate plane is established as follows, （3）， In the formula, yes The grid-side current in the coordinate system is: yes The grid voltage in the coordinate system is: Indicates the grid-side inductance value, Indicates the grid side resistance value, yes The voltage of the voltage source converter in the coordinate system; Substituting expressions (2) and (3) into the instantaneous power model, we obtain the following expression: （4）， S2. Perform backward Euler discretization on expression (4) in step S1 and convert it into the following expression: （5）， In expression (5), express The variable value at the time, where is a general term for variables, which can represent , or ; express The variable value at the time, represents the control cycle, yes The voltage of the converter at time k in the coordinate system Quantity, yes The voltage of the converter at time k in the coordinate system Quantity, yes The grid voltage at time k in the coordinate system Quantity, yes The grid voltage at time k in the coordinate system Quantity, ] is the grid-side active power at time k+1, is the grid-side reactive power at time k+1; S3, using the nominal value of the grid-side inductance And the nominal value of the grid side resistance Participate in the prediction calculation respectively, the instantaneous power model is as follows: （6）， In the following table, "no" represents the nominal value. and are interference parameters; S4. Set the deadbeat control as follows: Assuming that the drive system achieves the expected behavior at the end of each control cycle, the required voltage vector is calculated as follows: and , and substitute it into expression (6), we get the following expression: ， In the formula, and is The estimated disturbance has been obtained in the interval, yes The grid voltage at time k in the coordinate system; represents the expected instantaneous active power required by the motor side, where = , is the torque reference, torque reference Through the speed proportional-integral controller output of the switched reluctance motor, is the angular velocity of the switched reluctance motor, and the angular velocity Calculated in the position estimator by the feedback encoder signal on the motor shaft from the switched reluctance motor; Indicates reactive power reference; S5: The voltage vector calculated in step S4 is output and input to the voltage source converter through a conventional SVPWM module.

2. The integrated control method of a high-speed switched reluctance motor drive system according to claim 1, characterized in that: The position between each two phases of the switched reluctance motor is determined according to the Power on in sequence, is the position of the switched reluctance motor, the position A feedback encoder signal from the motor shaft of the switched reluctance motor is calculated on a position estimator.

3. The integrated control method of a high-speed switched reluctance motor drive system according to claim 1, characterized in that: Add step S3-1 between completing step S3 and step S4; S3-1. Assume that in expression (6) and The value of is constant in each sampling interval, and the instantaneous power model is as follows, （6-1）， In the formula, Represents a set of defined variables, including 4 variables; , represents the observer matrix gain, represents the active disturbance at time k+1, represents the reactive disturbance at time k+1, represents the active power estimation at time k, represents the active power estimation at time k+1, represents the reactive power estimation at time k, represents the reactive power estimation at time k+1; is a mathematical matrix, ; in, , , and According to expression (6-1), the instantaneous power at the next moment is calculated, where: and Respectively Obtained within the range of and Obtained from the last interval, calculated at the initial time k=0 hour = =0.

Images