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

Abstract

This invention discloses an integrated control method for a high-speed switched reluctance motor drive system. The drive system includes a voltage source converter (VSC), with each phase of a three-phase AC power supply connected sequentially to the power input terminal of the VSC via resistors and inductors. The switched reluctance motor is driven by an SRM driver, which is interconnected with the voltage source converter. This method establishes an instantaneous power model and calculates the required voltage vector (i.e., P-DBC) by assuming the drive system reaches the expected behavior at the end of each control cycle. This yields the drive voltage of the SRM driver, which is directly provided by the VSC through instantaneous active power control of the P-DBC. This establishes a direct power connection between the VSC and the SRM, and controls the entire system by manipulating the instantaneous power flow.

Description

Technical Field

[0001] This invention relates to the field of switched reluctance motor technology, and more specifically to an integrated control method for a high-speed switched reluctance motor drive system. Background Technology

[0002] Switched reluctance motors have a simple structure, with no windings on the rotor. The motor itself has high mechanical strength and can be used for frequent start-stop or ultra-high-speed operation.

[0003] In existing technologies, such as Figure 1a As shown, switched reluctance motors (SRMs) use diode bridge rectifiers (DBRs) to drive SRM drivers. However, while using DBRs reduces the cost of the drive system, it induces a large amount of reactive power and current harmonics in the power grid, which degrades power quality. In some cases, the reactive power exceeds the active power. Furthermore, the uncontrollable DC bus voltage of the DBR is easily affected by the operating conditions of the SRM driver. Therefore, some researchers use DC power to drive SRM drivers, such as... Figure 1b As shown, this method solves the above problem, but the switched reluctance motor drive system obtained by this method is expensive.

[0004] Furthermore, in existing switched reluctance motor drive systems, such as Figure 2 As shown, both the front-end converter and the back-end SRM driver 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. This makes the structure of the switched reluctance motor drive system relatively complicated.

[0005] In view of this, this application has conducted in-depth research on this basis, resulting in this case. Summary of the Invention

[0006] The purpose of this 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, and has a lower cost, making the switched reluctance motor drive system more simplified.

[0007] To achieve the above objectives, the solution of the present invention is:

[0008] An integrated control method for a high-speed switched reluctance motor drive system is characterized in that the drive system includes a voltage source converter, and each phase of the three-phase AC power supply is sequentially connected to a resistor. and inductor The voltage source converter is connected to its power input terminal, and the switched reluctance motor is driven by an SRM driver, which is interconnected with the voltage source converter; the process includes the following steps:

[0009] S1. The instantaneous power model in the stationary α, β coordinate plane is established as follows.

[0010] (1), where, Instantaneous active power Instantaneous reactive power yes grid-side voltage in coordinate system Quantity, yes grid-side voltage in coordinate system Quantity, yes Current on the grid side in the coordinate system;

[0011] and The relational expression is as follows:

[0012] (2),

[0013] In the formula, Represents the angular frequency of the grid-side voltage, where , Indicates the power grid frequency;

[0014] The voltage source conversion model in the stationary α, β coordinate plane is established as follows.

[0015] (3),

[0016] In the formula, yes Current on the grid side in the coordinate system yes Grid-side voltage in coordinate system Indicates the value of the grid-side inductance. Indicates the grid-side resistance value. yes Voltage of the voltage source converter in the coordinate system;

[0017] Substituting expressions (2) and (3) into the instantaneous power model, we obtain the following expression:

[0018] (4),

[0019] S2. Perform backward Euler discretization on expression (4) in step S1, transforming it into the following expression:

[0020] (5),

[0021] In expression (5), express The variable value at time , where is a collective term for a variable that can represent , or ; express The variable value at time, Indicates the control period. yes The converter voltage at time k in the coordinate system Quantity, yes The converter voltage at time k in the coordinate system Quantity, yes The grid-side voltage at time k in the coordinate system Quantity, yes The grid-side voltage at time k in the coordinate system Quantity, [ ] is the active power on the grid side at time k+1. It is the grid-side reactive power at time k+1;

[0022] S3, Using the nominal value of the grid-side inductance. and grid-side resistance nominal value The instantaneous power model, which is used for prediction calculations, is as follows:

[0023] (6),

[0024] In the formula, "no" in the table below represents the nominal value. and These are all interference parameters;

[0025] S4. Set up deadbeat control as follows: Assuming the drive system reaches the expected behavior at the end of each control cycle, the required voltage vector is calculated as follows, let... and Substituting this into expression (6), we obtain the following expression:

[0026] ,

[0027] In the formula, and Is The estimated disturbances already obtained within the interval. yes Grid-side voltage at time k in the coordinate system; This represents the desired instantaneous active power required on the motor side, where = , For torque reference, torque reference The speed output is obtained through the proportional-integral controller of the switched reluctance motor. The angular velocity of the switched reluctance motor. The position is calculated in the position estimator using feedback encoder signals from the motor shaft of the switched reluctance motor. Indicates reactive power reference;

[0028] S5. Calculate the voltage vector obtained in step S4. The output is then fed into the voltage source converter via a conventional SVPWM module.

[0029] The switched reluctance motor is positioned according to the position of each pair of phases. Power on in sequence, The position of the switched reluctance motor, the position The position is calculated on the position estimator using the feedback encoder signal of the motor shaft of the switched reluctance motor.

[0030] Add step S3-1 between completing step S3 and step S4;

[0031] S3-1, Assuming expression (6) and The value of is constant in each sampling interval period, and the instantaneous power model is as follows.

[0032] (6-1)

[0033] In the formula, Represents the defined set of variables, containing 4 variables; , Represents the gain of the observer matrix. This represents the active power disturbance at time k+1. This represents the reactive power disturbance at time k+1. This represents the estimated active power at time k. This represents the estimated active power at time k+1. This represents the reactive power estimate at time k. This represents the reactive power estimate at time k+1;

[0034] It is a mathematical matrix. ;

[0035] in, , , and Predictions are made according to expression (6-1) to calculate the instantaneous power at the next moment, where, and In respectively Obtained within the interval, and Obtained from the last interval, calculated at the initial time k=0. hour = =0.

[0036] By adopting the above method, the present invention has the following beneficial effects: The present invention establishes a direct power connection between the voltage source converter and the SRM driver, thereby treating the voltage source converter and the SRM driver as a whole, which simplifies the switched reluctance motor drive system and reduces costs; Furthermore, the present invention controls the instantaneous active power flowing to the motor side, thereby simultaneously achieving controllable speed, energy feedback, near-uniform grid-side power factor, and low grid-side current distortion. Combined with predictive deadbeat control with a disturbance observer, it ensures that the instantaneous active power and instantaneous reactive power simultaneously track their respective reference values ​​without steady-state error, thus achieving satisfactory power quality and energy feedback. Attached Figure Description

[0037] Figure 1a This is a schematic diagram of a switched reluctance motor driven by a diode bridge rectifier.

[0038] Figure 1b This is a schematic diagram of a switched reluctance motor driven by a DC power supply.

[0039] Figure 2 This is a schematic diagram of independent control in an existing drive system.

[0040] Figure 3 This is a schematic diagram of the topology of the drive system.

[0041] Figure 4 This is a block diagram illustrating the principle of the integrated control method for the drive system. Detailed Implementation

[0042] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0043] This invention provides an integrated control method for a high-speed switched reluctance motor drive system, such as... Figure 3-4 As shown, the drive system uses a conventional three-phase AC power supply and includes a voltage source converter (VSC) and an asymmetrical half-bridge controller (AHBC). Both the VSC and AHBC are electrically connected to each other in a conventional manner. The asymmetrical half-bridge controller can be a conventional half-bridge controller, and the voltage source converter can be a conventional three-phase voltage-source rectifier. Each phase of the three-phase AC power supply is sequentially connected to a resistor. and inductor Connect the corresponding power input terminal of the voltage source converter; in this embodiment, the AHBC mentioned above is the SRM driver, wherein the SRM driver is a conventional driver used to drive a switched reluctance motor (SRM), and it is connected to the switched reluctance motor (SRM) in a conventional manner.

[0044] The integrated control method provided in this embodiment is based on the topology of the above-mentioned drive system to drive the high-speed SRM, and includes the following steps:

[0045] S1. The instantaneous power model in the stationary α, β coordinate plane is established as follows.

[0046] (1),

[0047] In the formula, Instantaneous active power Instantaneous reactive power , yes grid-side voltage in coordinate system Quantity, yes Current on the grid side in the coordinate system;

[0048] and The relational expression is as follows: (2), where, Represents the angular frequency of the grid-side voltage, where , Indicates the power grid frequency;

[0049] The voltage source conversion model in the stationary α, β coordinate plane is established as follows. (3),

[0050] In the formula, yes Current on the grid side in the coordinate system yes Voltage on the grid side in the coordinate system Indicates the value of the grid-side inductance. Indicates the grid-side resistance value. yes Voltage of the voltage source converter in the coordinate system;

[0051] Substituting expressions (2) and (3) into the instantaneous power model, that is, substituting expressions (2) and (3) into expression (1), we obtain the following expressions:

[0052] (4);

[0053] S2. Perform backward Euler discretization on expression (4) in step S1, transforming it into the following expression:

[0054] (5),

[0055] In expression (5), Indicates the control period. yes The converter voltage at time k in the coordinate system Quantity, yes The converter voltage at time k in the coordinate system Quantity, yes The grid-side voltage at time k in the coordinate system Quantity, yes The grid-side voltage at time k in the coordinate system Quantity, [ ] is the active power on the grid side at time k+1. It is the grid-side reactive power at time k+1; among which, express The variable value at time, express The variable value at time, here It is a collective term for variables that can represent , and .

[0056] It should be noted that when the inductor and resistance When the actual values ​​are substituted into the above expression (5), the expression holds true. However, due to the inductance... and resistance These are all unknown values, and the values ​​measured by the measuring instruments all have errors. Moreover, these values ​​will change with environmental factors such as temperature. Therefore, the values ​​of these parameters are uncertain. and resistance These are actually all nominal values, i.e., inductance. and resistance All of these parameters were included in the prediction calculation, and the aforementioned uncertainty parameters were treated as dynamic disturbances.

[0057] S3, Using the nominal value of the grid-side inductance. and grid-side resistance nominal value Substituting them into expression (5), we obtain the instantaneous power model as follows:

[0058] (6),

[0059] In the formula, "no" in the table below represents the nominal value. and These are all interference parameters; and Is The estimated disturbances already obtained within the interval.

[0060] S4, assuming the above expression (6) and The value of is constant in each sampling interval period, then the instantaneous power model at the next time step (time step k+1) is as follows:

[0061] (6-1)

[0062] In the formula, and Is The estimated disturbances already obtained within the interval. ;

[0063] Represents the defined set of variables, including These four variables; It is the active disturbance at time k+1. It is the reactive power disturbance at time k+1. It is the active power estimate at time k. It is the active power estimate at time k+1. It is the reactive power estimate at time k. It is the reactive power estimate at time k+1. The meaning, It is an artificially defined observer matrix used to simplify the formula; , These are the observer matrix gains, all parameters that are manually set in a conventional manner.

[0064] S5. Deadbeat Control (P-DBC) is as follows: Assuming the drive system reaches 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:

[0065] ,

[0066] In the formula, This represents the desired instantaneous active power required on the motor side; This represents the reactive power reference, a parameter given manually in a conventional manner;

[0067] in, = In the formula, For SRM torque reference, and Output via a conventional speed PI controller; For the location of SRM, The angular velocity of the SRM, and the position of the SRM. and angular velocity The position is calculated in the position estimator using feedback encoder signals from the motor shaft of the SRM. It is standard practice to install the feedback encoder and position estimator separately on the motor. and angular velocity The calculation is also a conventional technique, so it will not be described in detail. In this embodiment, the drive system adopts predictive deadbeat control (P-DBC) with a disturbance observer.

[0068] It should be noted that the aforementioned deadbeat control (P-DBC) refers to calculating the required variables by assuming that the system reaches the expected behavior at the end of each control cycle; specifically, P-DBC with a disturbance observer ensures that the input active power p and reactive power q follow... and At unit PF .

[0069] S6. Calculate the voltage vector obtained in step S5. The output is then fed into the voltage source converter via a conventional SVPWM module.

[0070] It is worth mentioning that, in this embodiment, the error caused by mismatched parameters is considered to be the converter voltage expression required for correction (i.e., expression). This provides robust control by mitigating interference from other systems.

[0071] Furthermore, in this invention, taking instantaneous k as an example, the implementation method of P-DBC with a perturbation observer is described as follows.

[0072] First, based on the measurements and and Then, using the above values, the updated and Substituting into expression (7), the required converter voltage is calculated. The converter voltage is the same as the voltage of the SRM driver in the drive system. and Measured using conventional methods.

[0073] Among them, the above-mentioned and These are manually set values; when the set value is changed... and It will be updated.

[0074] The above and The following formulas were used to calculate the results respectively:

[0075] .

[0076] To elaborate further, , , and By making predictions according to the above expression (6-1), and substituting the relevant variable data into expression (6-1), the power for the next time step (i.e., time k+1) can be obtained; where, and In respectively The interval is obtained. and The retrieval process is iterative, allowing the result from the previous step to be retrieved; it's worth noting that, due to... and It is obtained from the last interval, therefore, at the initial time, i.e., when k=0, the calculation is performed. hour = =0; where the above steps are the process of model predictive control to make the model more accurate.

[0077] It should be noted that, as Figure 4 As shown, the parameters of the improved part in this invention can all be obtained using conventional switched reluctance motor drive technology. For example, the conduction angle and turn-off angle are respectively input to the overcurrent protection module, and the overcurrent protection output... , , and For example, the output of a three-phase AC power supply and .

[0078] Furthermore, the conduction angle and turn-off angle of the phase winding each form a predefined lookup table to use different conduction angles and turn-off angles at different speeds. The conduction angle and turn-off angle are determined in advance by the drive system described below through experiments.

[0079] In this invention, since the SRM driver can be considered as the load of the VSC, the output active power of the VSC (denoted as ) The active power consumed by the DC bus capacitor (denoted as ) The sum of active power and active power, the power consumed by the SRM drive (denoted as ) ),Right now The power flow process of the drive system of the present invention is described in detail below.

[0080] Assumption > ,because The DC bus voltage increases, and since the DC bus voltage is applied to the winding terminals in every conduction region, it causes... Increase The increase makes Decrease Continue to increase until ,Right now .

[0081] Assumption < ,because The DC bus voltage decreases, causing Decrease, so that Gradually approaching zero, hour, Stop decreasing.

[0082] Therefore, Adjustable That is, constant Represents constant Therefore, in this invention, the speed of the SRM is adjusted by directly controlling the active power flowing to the motor side, and the aforementioned predictive deadbeat control can ensure that the active power flowing to the motor side follows the aforementioned... This achieves energy feedback, returning excess active power to the grid; furthermore, this embodiment sets in step S5... This is to improve the grid-side power factor (PF) and current harmonics.

[0083] In the integrated control method of this invention, a power control method is proposed to simultaneously manage the front-end voltage source converter and the back-end switched reluctance motor, 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 driver are regarded as a whole to simplify the system. Furthermore, the P-DBC with a disturbance observer can ensure that active power and reactive power simultaneously track their reference values ​​without steady-state error, achieving satisfactory SRM control performance. Specifically, the P-DBC uses inaccurate system parameters in the calculation. The error between the reference power and the actual power is considered as a disturbance term. The feedforward effect of the error ensures that the estimated disturbance term is added to the calculated voltage reference, thereby providing stable control. Therefore, the errors caused by the mismatch of nominal values ​​and the variation of actual parameter values ​​can be compensated by adding additional terms to the expression of the desired voltage vector.

[0084] The above description is only a preferred embodiment of this invention. Any equivalent changes and modifications made within the scope of the claims of this invention shall fall within the scope of the claims of this 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, where each phase of the three-phase AC power supply passes through a resistor in sequence. and inductor The voltage source converter is connected to its power input terminal, and the switched reluctance motor is driven by an SRM driver, which is interconnected with the voltage source converter; the process includes the following steps: S1. The instantaneous power model in the stationary α, β coordinate plane is established as follows. (1), where, Instantaneous active power Instantaneous reactive power yes grid-side voltage in coordinate system Quantity, yes grid-side voltage in coordinate system Quantity, yes Current on the grid side in the coordinate system; and The relational expression is as follows: （2）， In the formula, Represents the angular frequency of the grid-side voltage, where , Indicates the power grid frequency; The voltage source conversion model in the stationary α, β coordinate plane is established as follows. （3）， In the formula, yes Current on the grid side in the coordinate system yes Voltage on the grid side in the coordinate system Indicates the value of the grid-side inductance. Indicates the grid-side resistance value. yes 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, transforming it into the following expression: （5）， In expression (5), express The variable value at time , where is a collective term for a variable that can represent , or ; express The variable value at time, Indicates the control cycle. yes The converter voltage at time k in the coordinate system Quantity, yes The converter voltage at time k in the coordinate system Quantity, yes The grid-side voltage at time k in the coordinate system Quantity, yes The grid-side voltage at time k in the coordinate system Quantity, [ ] is the active power on the grid side at time k+1. It is the grid-side reactive power at time k+1; S3, Using the nominal value of the grid-side inductance. and grid-side resistance nominal value The instantaneous power model, which is used for prediction calculations, is as follows: （6）， In the formula, "no" in the table below represents the nominal value. and These are all interference parameters; S4. Set up deadbeat control as follows: Assuming the drive system reaches the expected behavior at the end of each control cycle, the required voltage vector is calculated as follows, let... and Substituting this into expression (6), we obtain the following expression: ， In the formula, and Is The estimated disturbances already obtained within the interval. yes Grid-side voltage at time k in the coordinate system; This represents the desired instantaneous active power required on the motor side, where = , For torque reference, torque reference The speed output is obtained through the proportional-integral controller of the switched reluctance motor. The angular velocity of the switched reluctance motor. The position is calculated in the position estimator using feedback encoder signals from the motor shaft of the switched reluctance motor. Indicates reactive power reference; S5. Calculate the voltage vector obtained in step S4. The output is then fed into the voltage source converter via a conventional SVPWM module.

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

3. The integrated control method for 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, Assuming expression (6) and The value of is constant in each sampling interval period, and the instantaneous power model is as follows. （6-1）， In the formula, Represents the defined set of variables, containing 4 variables; , Represents the gain of the observer matrix. This represents the active power disturbance at time k+1. This represents the reactive power disturbance at time k+1. This represents the estimated active power at time k. This represents the estimated active power at time k+1. This represents the reactive power estimate at time k. This represents the reactive power estimate at time k+1; It is a mathematical matrix. ; in, , , and Predictions are made according to expression (6-1) to calculate the instantaneous power at the next moment, where, and In respectively Obtained within the interval, and Obtained from the last interval, calculated at the initial time k=0. hour = =0.

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