Switched reluctance motor voltage modulation method, device and system based on effective vector

Abstract

This invention discloses a method, apparatus, and system for voltage modulation of a switched reluctance motor based on effective vectors, belonging to the field of motor drive control, including: obtaining the rotating voltage component u of the switched reluctance motor corresponding to a voltage reference value during the current switching cycle. αβ and zero-sequence voltage component u z ; for u αβ By decomposition, the rotating voltage components U of the two converters in the open-winding motor driver are obtained. αβ1 and U αβ2 And calculate the action time T' of the first effective vector and the second effective vector of the two converters respectively. x1 T' y1 T' x2 and T' y2 This enables the two converters to achieve u z The modulation, and the rotating voltage components are U αβ1 and U αβ2 According to T' x1 T' y1 T' x2 and T' y2 The duty cycle of each bridge arm in each converter is calculated, and the remaining time is filled using a single zero vector; the switching signal of each bridge arm in both converters is determined based on the duty cycle. This invention achieves modulation of both rotating voltage components and zero-sequence voltage components simultaneously through effective vector allocation, thereby reducing the number of switching operations within each switching cycle.

Description

Technical Field

[0001] This invention belongs to the field of motor drive control, and more specifically, relates to a method, apparatus and system for voltage modulation of switched reluctance motors based on effective vector. Background Technology

[0002] With the transformation and upgrading of industrial structure, modern industry and equipment manufacturing are increasingly demanding higher performance and reliability from power drive systems. Unlike traditional motors, switched reluctance motors open the neutral point of their windings and are driven by an open-winding motor driver. The two ends of the windings are connected to the output of a converter. They possess technological advantages such as large capacity, high integration, high voltage utilization, and high reliability, and have broad application prospects, attracting extensive research from numerous experts and scholars both domestically and internationally.

[0003] However, due to the structure of open-winding motor drivers, the two converters used to drive the switched reluctance motor are powered by the same power supply and connected by a common DC bus, resulting in a zero-sequence current path. This necessitates that the voltage modulation strategy for the switched reluctance motor simultaneously considers the modulation of both the rotating voltage component and the zero-sequence voltage component. Through voltage modulation, the voltage components of the switched reluctance motor can be made close to or equal to the specified command values. In traditional research, space vector pulse width modulation (SVM) is typically used, employing effective and zero vectors to modulate the rotating and zero-sequence voltage components respectively. This results in a complex switching sequence for the converter, leading to a higher number of switching operations and greater switching losses, thereby reducing the operating efficiency of the switched reluctance motor system and affecting the lifespan of the power devices. Summary of the Invention

[0004] To address the shortcomings and improvement needs of existing technologies, this invention provides a method, apparatus, and system for voltage modulation of switched reluctance motors based on effective vectors. The purpose is to simultaneously modulate the rotating voltage component and the zero-sequence voltage component through effective vector allocation, thereby reducing the number of switching cycles in each switching cycle, reducing switching losses, and improving system operating efficiency and reliability.

[0005] To achieve the above objectives, according to one aspect of the present invention, a voltage modulation method for a switched reluctance motor based on effective vector is provided, comprising: performing the following steps in each switching cycle:

[0006] (S1) Collect the rotor electrical angle θ of the switched reluctance motor during the current switching cycle. e and the voltage reference value u in the synchronous rotating coordinate system dq0 * After coordinate transformation, the rotating voltage component u of the switched reluctance motor is obtained. αβ and zero-sequence voltage component u z ;

[0007] (S2) For the rotating voltage component u αβ By decomposition, the rotational voltage components U of the first and second converters in the open-winding motor driver of the switched reluctance motor are obtained. αβ1 and U αβ2 And calculate the duration T' of the first effective vector and the second effective vector of the first converter within the current switching cycle. x1 and T' y1 And the action time T' of the first and second effective vectors of the second converter. x2 and T' y2 This enables the two converters to achieve the zero-sequence voltage component u. z The modulation of the output rotating voltage components is as follows: αβ1 and U αβ2 ;

[0008] The first effective vector is the common-mode voltage amplitude U. dc The effective vector is 3, and the second effective vector generates a common-mode voltage amplitude of 2*U. dc / 3 effective vector; U dc This is the DC bus voltage;

[0009] (S3) Based on the action time T' x1 T' y1 T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, and fill the remaining time using a single zero vector;

[0010] (S4) Determine the switching signal of each bridge arm in the two converters according to the duty cycle and input it to the open winding motor driver to complete the voltage modulation in the current switching cycle.

[0011] In some optional embodiments, in step (S3), when the remaining time in the current period is filled using the zero vector U0, the action time T' is used as a reference. x1 T' y1 T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, including:

[0012] Calculate the maximum duty cycle D of the three arms in the converter using the following formula. 1n The median value D 2n and minimum value D 3n :

[0013]

[0014] After determining the sector number of the converter, determine the duty cycle D of the bridge arm connected to the A, B, and C phase windings of the switched reluctance motor in the converter according to the following correspondence. an D bn and D cn :

[0015]

[0016] In step (S3), when the remaining time in the current period is filled using the zero vector U7, it is based on the action time T' x1 T' y1 T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, including:

[0017] Calculate the maximum duty cycle D of the three arms in the converter using the following formula. 1n The median value D 2n and minimum value D 3n :

[0018]

[0019] After determining the sector number of the converter, determine the duty cycle D of the bridge arm connected to the A, B, and C phase windings of the switched reluctance motor in the converter according to the following correspondence. an D bn and D cn :

[0020]

[0021] Where n takes the value 1 or 2; when n = 1, D 1n D 2n and D 3n , and D an D bn and D cn All are the duty cycles of the bridge arms in the first converter; when n=2, D 1n D 2n and D 3n , and D an D bn and D cn All are the duty cycles of the bridge arms in the second converter; T s The zero vector U0 is the vector when all three bridge arms' switches are at a low level, and the zero vector U7 is the vector when all three bridge arms' switches are at a high level.

[0022] Further, in step (S2), the action time T' of the first effective vector and the second effective vector of the first converter within the current switching cycle is calculated. x1and T' y1 And the action time T' of the first and second effective vectors of the second converter. x2 and T' y2 ,include:

[0023] (S21) Calculate the rotating voltage component U of the first converter during the current switching cycle. αβ1 The corresponding action time T of the first and second effective vectors x1 and T y1 And the rotating voltage component U of the second converter αβ2 The corresponding action time T of the first and second effective vectors x2 and T y2 ;

[0024] (S22) Calculate the zero-sequence voltage component u of the switched reluctance motor using the second effective voltage vector of the two converters. z During modulation, the second effective vector action time of each converter is relative to T. y1 and T y2 Correction amount T z1 and T z2 ;

[0025] (S23) Using the correction amount T z1 and T z2 For the duration T x1 T y1 T x2 and T y2 After correction, the action time T' of the first effective vector and the second effective vector of the first converter within the current switching cycle is obtained. x1 and T' y1 And the action time T' of the first and second effective vectors of the second converter. x2 and T' y2 This enables the two converters to achieve the zero-sequence voltage component u. z The modulation of the output rotating voltage components is as follows: αβ1 and U αβ2 .

[0026] Further, in step (S21), T is calculated as follows: x1 T y1 T x2 and T y2 :

[0027] Calculate intermediate variable tmp1 n tmp2 n and tmp3 n :

[0028]

[0029] After determining the sector number where the converter is located, the action time T of the first and second effective vectors is determined according to the following correspondence. xn and T yn :

[0030]

[0031] Where n takes the value 1 or 2; when n = 1, tmp1 n tmp2 n and tmp3 n All are intermediate variables in the first converter, U α1 and U β1 The rotating voltage components U of the first converter are respectively αβ1 α and β axis components; when n = 2, tmp1 n tmp2 n and tmp3 n All are intermediate variables in the second converter, U α2 and U β2 The rotating voltage component U of the second converter are respectively αβ2 The α and β axis components.

[0032] Furthermore, in step (S3), when the remaining time in the current period is filled using the zero vector U0, in step (S22), T z1 =T z2 =u z T s / (2U dc );

[0033] Wherein, the zero vector U0 is the vector when all three switches on the bridge arm are at a low level, and T s The switching cycle.

[0034] Furthermore, in step (S3), when the remaining time in the current period is filled using the zero vector U7, in step (S22), the correction amount T is calculated as follows: z1 and T z2 :

[0035] When the first inverter is located in sector I, III, or V, T z1 =0;T z2 =-(U z T s )U dc ;

[0036] When the first inverter is located in sector II, IV, or VI, T z1 =-(U z Ts )U dc ;T z2 =0;

[0037] Wherein, zero vector U7 is the vector when all three bridge arm switches are at a high level, T s The switching cycle.

[0038] Furthermore, in step (S23), the correction amount T is used. z1 and T z2 For the duration T x1 T y1 T x2 and T y2 Make corrections, including:

[0039] Determine the sector where the first converter is located. When the first converter is located in sector I, III, or V, correct it as follows:

[0040]

[0041] When the first converter is located in sector II, IV, or VI, the correction shall be made as follows:

[0042]

[0043] According to another aspect of the present invention, a voltage modulation device for a switched reluctance motor based on an effective vector is provided, comprising:

[0044] The coordinate transformation module is used to acquire the rotor electrical angle θ of the switched reluctance motor during the current switching cycle. e and the voltage reference value u in the synchronous rotating coordinate system dq0 * After coordinate transformation, the rotating voltage component u of the switched reluctance motor is obtained. αβ and zero-sequence voltage component u z ;

[0045] The winding voltage modulation module is used to modulate the rotating voltage component u. αβ By decomposition, the rotational voltage components U of the first and second converters in the open-winding motor driver of the switched reluctance motor are obtained. αβ1 and U αβ2 And calculate the duration T' of the first effective vector and the second effective vector of the first converter within the current switching cycle. x1 and T' y1 And the action time T' of the first and second effective vectors of the second converter. x2 and T' y2 This enables the two converters to achieve the zero-sequence voltage component u. zThe modulation of the output rotating voltage components is as follows: αβ1 and U αβ2 The first effective vector is the common-mode voltage amplitude U. dc The effective vector is 3, and the second effective vector generates a common-mode voltage amplitude of 2*U. dc / 3 effective vector; U dc This is the DC bus voltage;

[0046] The duty cycle calculation module is used to calculate the duty cycle based on the action time T'. x1 T' y1 T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, and fill the remaining time using a single zero vector;

[0047] And a carrier comparison module, used to determine the switching signal of each bridge arm in the two converters according to the duty cycle, and input it to the open winding motor driver to complete the voltage modulation in the current switching cycle.

[0048] According to another aspect of the present invention, a switched reluctance motor system is provided, comprising: a switched reluctance motor and an open-winding motor driver thereof, and the above-described effective vector-based switched reluctance motor voltage modulation device provided by the present invention.

[0049] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0050] (1) The voltage modulation method for switched reluctance motors based on effective vectors provided by this invention simultaneously modulates the rotating voltage component and the zero-sequence voltage component by allocating effective vectors. Furthermore, when calculating the duty cycle of each bridge arm in the converter, the remaining time is filled using only a single zero vector. This ensures that within each switching cycle, the two zero vectors of the same converter will not appear simultaneously; instead, only one first effective vector, one second effective vector, and one zero vector exist. Moreover, the modulation of both the rotating voltage component and the zero-sequence voltage component is undertaken by the effective vectors, independent of the zero vectors. This reduces the switching sequence complexity of the converter and effectively reduces the number of switching operations, thereby reducing switching losses and improving system operating efficiency and reliability. Experiments show that this invention can reduce the number of switching operations in each switching cycle by one-third.

[0051] (2) The voltage modulation method for switched reluctance motors based on effective vector provided by the present invention can effectively reduce the common-mode voltage amplitude of the switched reluctance motor while reducing the complexity of the switching sequence of the converter and the number of switching operations.

[0052] (3) The voltage modulation method for switched reluctance motors based on effective vectors provided by this invention, when utilizing the modulation of the zero-sequence voltage component of the effective vector, specifically modulates the second effective vector, i.e., generates a common-mode voltage amplitude of 2*U. dc The effective vector's duration is corrected by adjusting the duration of the second effective vector. Since the common-mode voltage amplitude generated by the second effective vector is greater than that of the first effective vector, the common-mode voltage amplitude is U. dc The effective vector is 3 / 3, therefore, the correction amount T can be reduced. z1 and T z2 The amplitude is reduced, thereby decreasing the linear modulation region shrinkage caused by the correction. Attached Figure Description

[0053] Figure 1 A schematic diagram of the structure of an existing open-winding motor driver with switched reluctance;

[0054] Figure 2 The voltage modulation method for switched reluctance motors based on effective vectors provided in this embodiment of the invention;

[0055] Figure 3 This is a schematic diagram of the rotating voltage component distortion caused by the use of effective vectors to achieve zero-sequence voltage component modulation in the two converters when the first converter is located in sector I, according to an embodiment of the present invention.

[0056] Figure 4 This is a schematic diagram of the rotating voltage component distortion caused by the use of effective vectors to achieve zero-sequence voltage component modulation in the two converters when the first converter is located in sector IV, according to an embodiment of the present invention.

[0057] Figure 5 This is a schematic diagram illustrating how carrier comparison is performed based on duty cycle to determine the bridge arm switching signal in an embodiment of the present invention;

[0058] Figure 6 This is a diagram of the switch signals for each bridge arm as determined in Embodiment 1 of the present invention;

[0059] Figure 7 The diagram shows the switching signals of each bridge arm determined using the traditional space vector pulse width modulation method.

[0060] Figure 8 This is a diagram of the switch signals for each bridge arm as determined in Embodiment 2 of the present invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0062] In this invention, the terms "first," "second," etc. (if present) in the invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0063] Before explaining the technical solution of the present invention in detail, the basic structure and modulation principle of the switched reluctance motor are briefly introduced as follows.

[0064] Figure 1 The diagram shows an open-winding motor driver for driving a switched reluctance motor. It includes two converters (hereinafter referred to as the first converter and the second converter), a DC power supply, and a DC bus capacitor. The switched reluctance motor is three-phase, with the two ends of the windings connected to the outputs of the two converters in the open-winding motor driver. Both converters are three-phase full-bridge structures, composed of fully controlled power devices with anti-parallel diodes. The two converters are connected together by a common DC bus and powered by the same DC power supply. The DC bus capacitor is connected across the DC power supply to stabilize the DC bus voltage U. dc .

[0065] To avoid generating non-ideal voltage harmonics, the rotating voltage components of the first and second converters have a 120° phase difference. Both the first and second converters have eight vectors, six of which are effective vectors that generate the rotating voltage component, and two are zero vectors that do not generate the rotating voltage component. The contributions of each vector to the rotating voltage component and common-mode voltage are shown in Table 1, where S... a S b S c They are respectively Figure 1 The drive signal for the upper switching transistor of the bridge arm connecting the converter to the A, B, and C phase windings of the switched reluctance motor is represented by 1 for high level and 0 for low level. It's easy to understand that a high level is the level that allows the switching transistor to conduct, and a low level is the level that prevents the switching transistor from conducting.

[0066] Table 1. Vectors of the converter

[0067]

[0068] In the following embodiment, based on the common-mode voltage amplitude, the six effective vectors of each converter are divided into two groups, and the common-mode voltage amplitude generated by the first group of effective vectors is U.dc / 3, including vectors U1, U3, and U5; the common-mode voltage amplitude generated by the second group of effective vectors is 2*U dc / 3, comprising vectors U2, U4, and U6. For ease of description, in the following embodiments, the first group of valid vectors is denoted as the first valid vector, and denoted by the symbol U. x The second set of effective vectors is denoted as the second effective vector, with the symbol U. y To express.

[0069] Existing switched reluctance motors use space vector pulse width modulation (SVM) to achieve voltage modulation. Specifically, the effective vector of the converter is used to modulate the rotating voltage component of the switched reluctance motor, and the zero vector of the converter is used to modulate the rotating voltage component of the switched reluctance motor. As a result, the switching sequence of the converter is complex, which leads to a large number of switching operations and large switching losses, thereby reducing the operating efficiency of the switched reluctance motor system and affecting the service life of power devices.

[0070] To address the technical problems of existing space vector pulse width modulation methods used in switched reluctance motor systems, such as high switching frequency, large switching losses, low operating efficiency, and low reliability, this invention provides a voltage modulation method, device, and system for switched reluctance motors based on effective vectors. The overall idea is to simultaneously modulate the rotating voltage component and the zero-sequence voltage component through effective vector allocation, and to use only one zero vector in each switching cycle, thereby reducing the complexity of the switching sequence and the number of switching times in one switching cycle.

[0071] The following is an example.

[0072] Example 1:

[0073] A voltage modulation method for switched reluctance motors based on effective vectors, such as... Figure 2 As shown, it includes: performing steps (S1) to (S4) in each switching cycle.

[0074] In this embodiment, step (S1) specifically involves: acquiring the rotor electrical angle θ of the switched reluctance motor during the current switching cycle. e and the voltage reference value u in the synchronous rotating coordinate system dq0 * After coordinate transformation, the rotating voltage component u of the switched reluctance motor is obtained. αβ and zero-sequence voltage component u z .

[0075] Voltage reference u of switched reluctance motor in synchronous rotating coordinate system dq0 * Including d-axis voltage reference value u d * q-axis voltage reference value uq * and 0-axis voltage reference value u0 * Rotating voltage component u αβ Including the α-axis rotational voltage component u α and β-axis rotating voltage component u β ;

[0076] According to the rotor electrical angle θ e For the voltage reference value u in the synchronous rotating coordinate system d * u q * u0 * By performing coordinate transformation, the rotating voltage component u of the switched reluctance motor is obtained. α u β and zero-sequence voltage component u z .

[0077] In this embodiment, step (S2) specifically involves: adjusting the rotating voltage component u. αβ By decomposition, the rotational voltage components U of the first and second converters in the open-winding motor driver of the switched reluctance motor are obtained. αβ1 and U αβ2 And calculate the duration T' of the first effective vector and the second effective vector of the first converter within the current switching cycle. x1 and T' y1 And the action time T' of the first and second effective vectors of the second converter. x2 and T' y2 This enables the two converters to achieve the zero-sequence voltage component u. z The modulation of the output rotating voltage components is as follows: αβ1 and U αβ2 ;

[0078] The first effective vector is the common-mode voltage amplitude U. dc The effective vector is 3, and the second effective vector generates a common-mode voltage amplitude of 2*U. dc / 3 effective vector; U dc This is the DC bus voltage.

[0079] like Figure 1 As shown, since the windings of the switched reluctance motor are connected between the outputs of the first and second converters, the rotating voltage component of the switched reluctance motor is equal to the difference between the rotating voltage components output by the two converters, and the zero-sequence voltage component of the switched reluctance motor is equal to the difference between the common-mode voltages output by the two converters. The relationship is expressed as follows:

[0080]

[0081] Among them, Uα1 U β1 U represents the α and β axis rotating voltage components of the first converter. CMV1 U is the common-mode voltage component of the first converter. α2 U β2 U represents the α and β axis rotating voltage components of the second converter. CMV2 This is the common-mode voltage component of the second converter; simultaneously, to avoid generating non-ideal voltage harmonics, the rotating voltage components of the first and second converters have a 120° phase difference; based on the above principle, according to the rotating voltage component u of the switched reluctance motor... α u β The rotating voltage components of the two converters are calculated using the following decomposition method:

[0082]

[0083] U α1 U β1 Together they constitute the rotating voltage component U of the first converter αβ1 U α2 U β2 Together they constitute the rotating voltage component U of the second converter αβ2 According to U αβ1 and U αβ2 The sectors where the first converter and the second converter are located can be determined separately.

[0084] In this embodiment, in step (S2), after obtaining the rotating voltage components U of the first converter and the second converter... αβ1 and U αβ2 Then, calculate the duration T' of the first effective vector and the second effective vector of the first converter within the current switching cycle according to the following steps. x1 and T' y1 And the action time T' of the first and second effective vectors of the second converter. x2 and T' y2 :

[0085] (S21) Calculate the rotating voltage component U of the first converter during the current switching cycle. αβ1 The corresponding action time T of the first and second effective vectors x1 and T y1 And the rotating voltage component U of the second converter αβ2 The corresponding action time T of the first and second effective vectors x2 and T y2 .

[0086] Based on vector projection calculation, T can be calculated. x1 T y1T x2 and T y2 Specifically, in step (S21), T is calculated as follows: x1 T y1 T x2 and T y2 :

[0087] Calculate intermediate variable tmp1 n tmp2 n and tmp3 n :

[0088]

[0089] After determining the sector number of the converter, the action time T of the first and second effective vectors is determined according to the correspondence shown in Table 2 below. xn and T yn :

[0090] Table 2. Duration of Effective Vectors in Different Sectors

[0091]

[0092] Where n takes the value 1 or 2; when n = 1, tmp1 n tmp2 n and tmp3 n All are intermediate variables in the first converter, U α1 and U β1 The rotating voltage components U of the first converter are respectively αβ1 α and β axis components; when n = 2, tmp1 n tmp2 n and tmp3 n All are intermediate variables in the second converter, U α2 and U β2 The rotating voltage component U of the second converter are respectively αβ2 The α and β axis components.

[0093] (S22) Calculate the zero-sequence voltage component u of the switched reluctance motor using the second effective voltage vector of the two converters. z During modulation, the second effective vector action time of each converter is relative to T. y1 and T y2 Correction amount T z1 and T z2 ;

[0094] This embodiment corrects the effective vector's action time, enabling the modulation of the zero-sequence voltage component of the switched reluctance motor using the effective vector. Thus, the modulation of both the rotational voltage component and the zero-sequence voltage component is undertaken by the effective vector, independent of the zero vector.

[0095] Since the common-mode voltage amplitude generated by the first effective vector is greater than that generated by the second effective vector, this embodiment modulates the zero-sequence voltage by correcting the second effective vector, thereby reducing the correction amount T. z1 and T z2 The amplitude is adjusted to reduce the linear modulation region reduction caused by the correction. The specific correction amount T is... z1 and T z2 The polarity of the duty cycle is related to the zero-sequence voltage component u of the switched reluctance motor, which is determined by the method used to calculate the duty cycle. z The polarities are the same. In this embodiment, to reduce the complexity of the switching sequence and the number of switching operations, after determining the duty cycle of the effective vector within the current switching cycle during duty cycle calculation, a single zero vector is used to fill the remaining time. In this embodiment, this zero vector is specifically U0, which is the vector when all three bridge arms' switches are at a low level. At this time, the correction amount T... z1 and T z2 The calculation method is as follows:

[0096] T z1 =T z2 =u z T s / (2U dc )

[0097] Among them, T s The switching cycle.

[0098] (S23) Using the correction amount T z1 and T z2 For the duration T x1 T y1 T x2 and T y2 After correction, the action time T' of the first effective vector and the second effective vector of the first converter within the current switching cycle is obtained. x1 and T' y1 And the action time T' of the first and second effective vectors of the second converter. x2 and T' y2 This enables the two converters to achieve the zero-sequence voltage component u. z The modulation of the output rotating voltage components is as follows: αβ1 and U αβ2 .

[0099] After the correction in step (S22), the second effective vector is related to both the rotating voltage component and the zero-sequence voltage component of the switched reluctance motor. Therefore, after the correction by the zero-sequence voltage component modulation module, the rotating voltage components generated by the two converters will be distorted to a certain extent.

[0100] Figure 3 When the first converter is located in sector I, this diagram illustrates the rotating voltage component distortion caused by the use of effective vectors to achieve zero-sequence voltage component modulation between the two converters. It can be seen that due to the 120° phase difference between the two converters, the first and second converters are located in sectors I and III respectively. At this time, the U of the two converters... y These are U2 and U4, respectively. To achieve zero-sequence voltage component modulation, the first and second converters need to additionally output vector U. 2_add and U 4_add This causes the actual output rotational voltage component to change from the original U. αβ1 and U αβ2 Distortion to U' αβ1 and U' αβ2 .

[0101] Similarly, Figure 4 This diagram illustrates the rotating voltage component distortion caused by the use of effective vectors to achieve zero-sequence voltage component modulation when the first converter is located in sector IV. It can be seen that, due to the 120° phase difference between the two converters, the first and second converters are located in sectors IV and VI respectively. At this time, the U of the two converters... y These are U4 and U6, respectively. To achieve zero-sequence voltage component modulation, the first and second converters need to output additional vector U4, respectively. add and U 6_add This will also cause the actual output rotational voltage component to change from the original U. αβ1 and U αβ2 Distortion to U' αβ1 and U' αβ2 .

[0102] To avoid the impact of rotating voltage component distortion on the normal operation of the switched reluctance motor, the duration T of the effective vectors of the two converters needs to be adjusted in different sectors. x1 T x2 T y1 T y2 The correction compensates for the rotational voltage component distortion caused by the use of effective vectors to achieve zero-sequence voltage component modulation in both converters. Specifically, when the first converter is located in sector I, III, or V, the correction is performed as follows:

[0103]

[0104] When the first converter is located in sector II, IV, or VI, the correction shall be made as follows:

[0105]

[0106] After the correction in step (S23), the distortion of the rotating voltage component caused by the modulation process can be compensated while the zero-sequence voltage component modulation is achieved using the effective vector.

[0107] In this implementation, step (S3) specifically involves: based on the action time T' x1 T' y1 T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, and fill the remaining time using the zero vector U0.

[0108] Compared to existing methods that simultaneously utilize two zero vectors, U0 and U7, to fill the remaining time within the current switching cycle, this embodiment uses only a single zero vector for filling. This ensures that within each switching cycle, the two zero vectors of the same converter will not appear simultaneously; instead, only one first effective vector, one second effective vector, and one zero vector exist. In this embodiment, since the zero vector U0 is used to fill the remaining time within the current switching cycle, according to the action time T'... x1 T' y1 T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, including:

[0109] Calculate the maximum duty cycle D of the three arms in the converter using the following formula. 1n The median value D 2n and minimum value D 3n :

[0110]

[0111] After determining the sector number of the converter, determine the duty cycle D of the bridge arm connected to the A, B, and C phase windings of the switched reluctance motor in the converter according to the correspondence shown in Table 3 below. an D bn and D cn :

[0112] Table 3 Duty cycles of each bridge arm of the converter in different sectors

[0113]

[0114] Where n takes the value 1 or 2; when n = 1, D1n D 2n and D 3n , and D an D bn and D cn All are the duty cycles of the bridge arms in the first converter; when n=2, D 1n D 2n and D 3n , and D an D bn and D cn All are the duty cycles of the bridge arms in the second converter; T s The switching cycle is denoted by ; the zero vector U0 is the vector when all three switches on the bridge arm are at a low level.

[0115] In this embodiment, step (S4) specifically involves: determining the switching signal of each bridge arm in the two converters according to the duty cycle, and inputting it to the open winding motor driver to complete the voltage modulation within the current switching cycle.

[0116] like Figure 5 As shown, for any bridge arm, the switching signal of that bridge arm can be determined by comparing the carrier wave based on its duty cycle. Specifically, when the duty cycle of the bridge arm is greater than that of the triangular carrier wave, the switching signal of the upper switch is high and the switching signal of the lower switch is low; conversely, when the duty cycle of the bridge arm is less than that of the triangular carrier wave, the switching signal of the upper switch is low and the switching signal of the lower switch is high. The switching signals of the upper and lower switches of each bridge arm are always complementary.

[0117] After carrier comparison based on the determined duty cycle, the switching signals of each bridge arm in the two converters are as follows: Figure 6 As shown, according to Figure 6 It can be seen that in each switching cycle, there are two bridge arms that do not switch. Figure 7 The diagram shown is a diagram of the switching signals of each bridge arm determined using the traditional space vector pulse width modulation method. Figure 7 It can be seen that all power devices perform switching actions within each switching cycle. (Comparison) Figure 6 and Figure 7 As can be seen, in this embodiment, the number of switching actions is reduced by one-third. Meanwhile, according to... Figure 6 As can be seen, in this embodiment, the common-mode voltage amplitude of the switched reluctance motor is 2 / 3U. dc ;according to Figure 7 It can be seen that, using the traditional space vector pulse width modulation method, the common-mode voltage amplitude of the switched reluctance motor is U. dc Therefore, this embodiment can also effectively reduce the common-mode voltage of the switched reluctance motor.

[0118] In summary, this embodiment achieves modulation of both the rotating voltage component and the zero-sequence voltage component through effective vector allocation, and uses only one zero vector in each switching cycle, which reduces the number of switching actions and the common-mode voltage of the switched reluctance motor.

[0119] Example 2:

[0120] A voltage modulation method for a switched reluctance motor based on effective vectors is presented in this embodiment, which is similar to Embodiment 1 above. The difference lies in that, in this embodiment, the remaining time in the current cycle is filled using the zero vector U7 when calculating the duty cycle. The zero vector U7 is the vector when all three bridge arms' switches are at a high level. Accordingly, in step (S22), the correction amount T is calculated as follows: z1 and T z2 :

[0121] When the first inverter is located in sector I, III, or V, T z1 =0;T z2 =-(U z T s )U dc ;

[0122] When the first inverter is located in sector II, IV, or VI, T z1 =-(U z T s )U dc ;T z2 =0;

[0123] In step (S3), based on the action time T' x1 T' y1 T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, including:

[0124] Calculate the maximum duty cycle D of the three arms in the converter using the following formula. 1n The median value D 2n and minimum value D 3n :

[0125]

[0126] After determining the sector number of the converter, determine the duty cycle D of the bridge arm connected to the A, B, and C phase windings of the switched reluctance motor in the converter according to the correspondence shown in Table 3. an D bn and D cn :

[0127] Where n takes the value 1 or 2; when n = 1, D 1nD 2n and D 3n , and D an D bn and D cn All are the duty cycles of the bridge arms in the first converter; when n=2, D 1n D 2n and D 3n , and D an D bn and D cn All are the duty cycles of the bridge arms in the second converter; T s U is the switching cycle; zero vector U7 is the vector when all three bridge arms' switches are at a high level.

[0128] The specific implementation methods of the remaining steps in this embodiment are the same as those in Embodiment 1 above, and will not be repeated here.

[0129] In this embodiment, after carrier comparison based on the determined duty cycle, the switching signals of each bridge arm in the two converters are as follows: Figure 8 As shown, according to Figure 8 As can be seen, similar to Embodiment 1 above, two bridge arms do not switch during each switching cycle. Meanwhile, according to... Figure 8 As can be seen, in this embodiment, the common-mode voltage amplitude of the switched reluctance motor is 2 / 3U. dc .contrast Figure 8 and Figure 7 As can be seen, in this embodiment, the number of switching actions is reduced by one-third, and this embodiment can also effectively reduce the common-mode voltage of the switched reluctance motor.

[0130] In summary, this embodiment achieves modulation of both the rotating voltage component and the zero-sequence voltage component through effective vector allocation, and uses only one zero vector in each switching cycle, which reduces the number of switching actions and the common-mode voltage of the switched reluctance motor.

[0131] Example 3:

[0132] A voltage modulation method for a switched reluctance motor based on effective vectors is disclosed in this embodiment, which is similar to Embodiments 1 and 2 described above. The difference lies in that, in this embodiment, when the first converter is located in sectors I, III, and V, the duty cycle calculation method in Embodiment 1 is used, that is, the zero vector U0 is used to fill the remaining time in the current switching cycle. When the first converter is located in sectors II, IV, and VI, the duty cycle calculation method in Embodiment 2 is used, that is, the zero vector U7 is used to fill the remaining time in the current switching cycle. The specific calculation method of the duty cycle can be found in the descriptions of Embodiments 1 and 2 described above, and will not be repeated here.

[0133] The two duty cycle calculation methods can be selected according to the requirements of the switched reluctance motor system. The selection has no impact on the voltage modulation of the switched reluctance motor. In this embodiment, the voltage stress balance of the power devices can be achieved by selecting the appropriate duty cycle calculation method by the sector where the converter is located.

[0134] Similarly, this embodiment can reduce the number of switching operations and reduce the common-mode voltage amplitude of the switched reluctance motor.

[0135] Example 4:

[0136] A voltage modulation device for a switched reluctance motor based on effective vector, comprising:

[0137] The coordinate transformation module is used to implement the above step (S1), that is, to collect the rotor electrical angle θ of the switched reluctance motor during the current switching cycle. e and the voltage reference value u in the synchronous rotating coordinate system dq0 * After coordinate transformation, the rotating voltage component u of the switched reluctance motor is obtained. αβ and zero-sequence voltage component u z ;

[0138] The winding voltage modulation module is used to implement the above step (S2), that is, to modulate the rotating voltage component u. αβ By decomposition, the rotational voltage components U of the first and second converters in the open-winding motor driver of the switched reluctance motor are obtained. αβ1 and U αβ2 And calculate the duration T' of the first effective vector and the second effective vector of the first converter within the current switching cycle. x1 and T' y1 And the action time T' of the first and second effective vectors of the second converter. x2 and T' y2 This enables the two converters to achieve the zero-sequence voltage component u. z The modulation of the output rotating voltage components is as follows: αβ1 and U αβ2 The first effective vector is the common-mode voltage amplitude U. dc The effective vector is 3, and the second effective vector generates a common-mode voltage amplitude of 2*U. dc / 3 effective vector; U dc This is the DC bus voltage;

[0139] The duty cycle calculation module is used to implement the above step (S3), that is, based on the action time T' x1 T' y1 T' x2 and T' y2Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, and fill the remaining time using a single zero vector;

[0140] And a carrier comparison module, used to implement the above step (S4), that is, to determine the switching signal of each bridge arm in the two converters according to the duty cycle and input it to the open winding motor driver to complete the voltage modulation in the current switching cycle.

[0141] In this embodiment, the specific implementation methods of each module can be referred to the descriptions in Embodiments 1 to 3 above, and will not be repeated here.

[0142] Example 5:

[0143] A switched reluctance motor system includes: a switched reluctance motor and its open-winding motor driver, as well as the switched reluctance motor voltage modulation device based on effective vector provided in Embodiment 4 above.

[0144] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A voltage modulation method for a switched reluctance motor based on effective vector, characterized in that, include: Perform the following steps during each switching cycle: (S1) Collect the rotor electrical angle of the switched reluctance motor during the current switching cycle. θ e Voltage reference value in synchronous rotating coordinate system u dq0 * After coordinate transformation, the rotating voltage component of the switched reluctance motor is obtained. u αβ and zero-sequence voltage component u z ; (S2) For the rotating voltage component u αβ By decomposition, the rotational voltage components of the first and second converters in the open-winding motor driver of the switched reluctance motor are obtained. U αβ1 and U αβ2 And calculate the duration of the first effective vector and the second effective vector of the first converter within the current switching cycle. T' x1 and T' y1 And the action time of the first and second effective vectors of the second converter. T' x2 and T' y2 This enables the two converters to achieve zero-sequence voltage components. u z The modulation, and the output rotating voltage components are respectively U αβ1 and U αβ2 ; The first effective vector is the common-mode voltage amplitude. U dc / 3 effective vector, the second effective vector is the one that generates a common-mode voltage amplitude of 2* U dc / 3 effective vector; U dc This is the DC bus voltage; (S3) Based on the duration of action T' x1 , T' y1 , T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, and fill the remaining time using a single zero vector; (S4) Determine the switching signal of each bridge arm in the two converters according to the duty cycle, and input it to the open winding motor driver to complete the voltage modulation in the current switching cycle.

2. The voltage modulation method for switched reluctance motors based on effective vectors as described in claim 1, characterized in that, In step (S3), the remaining time in the current period is calculated using the zero vector. U When filling 0, it is based on the action time. T' x1 , T' y1 , T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, including: Calculate the maximum duty cycle of the three arms in the converter using the following formula. D 1n median D 2n and minimum value D 3n : After determining the sector number of the converter, determine the duty cycle of the bridge arm connected to the A, B, and C phase windings of the switched reluctance motor in the converter according to the following correspondence. D an , D bn and D cn : In step (S3), the remaining time within the current switching cycle is calculated using the zero vector. U 7. When filling, according to the action time T' x1 , T' y1 , T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, including: Calculate the maximum duty cycle of the three arms in the converter using the following formula. D 1n median D 2n and minimum value D 3n : After determining the sector number of the converter, determine the duty cycle of the bridge arm connected to the A, B, and C phase windings of the switched reluctance motor in the converter according to the following correspondence. D an , D bn and D cn : in, n The value can be 1 or 2; n When =1, D 1n , D 2n and D 3n ,as well as D an , D bn and D cn All of these are the duty cycles of the bridge arms in the first converter; n When =2, D 1n , D 2n and D 3n ,as well as D an , D bn and D cn All of these are the duty cycles of the bridge arms in the second converter; T s For switching period; zero vector U 0 represents the vector when all three switches on the bridge arms are at a low level; the zero vector. U 7 is the vector when all the switches on the three bridge arms are at a high level.

3. The voltage modulation method for a switched reluctance motor based on effective vector as described in claim 2, characterized in that, In step (S2), the duration of action of the first effective vector and the second effective vector of the first converter within the current switching cycle is calculated. T' x1 and T' y1 And the action time of the first and second effective vectors of the second converter. T' x2 and T' y2 ,include: (S21) Calculate the rotating voltage component of the first converter during the current switching cycle. U αβ1 The corresponding action times of the first and second effective vectors T x1 and T y1 and the rotating voltage component of the second converter U αβ2 The corresponding action times of the first and second effective vectors T x2 and T y2 ; (S22) Calculate the zero-sequence voltage component of the switched reluctance motor using the second effective voltage vector of the two converters. u z During modulation, the second effective vector action time of each converter is relative to T y1 and T y2 Correction amount T z1 and T z2 ; (S23) Using the correction amount T z1 and T z2 Regarding the duration of action T x1 , T y1 , T x2 and T y2 After correction, the action time of the first effective vector and the second effective vector of the first converter within the current switching cycle is obtained. T' x1 and T' y1 And the action time of the first and second effective vectors of the second converter. T' x2 and T' y2 This enables the two converters to achieve zero-sequence voltage components. u z The modulation, and the output rotating voltage components are respectively U αβ1 and U αβ2 .

4. The voltage modulation method for a switched reluctance motor based on effective vector as described in claim 3, characterized in that, In step (S21), the calculation is performed as follows: T x1 , T y1 , T x2 and T y2 : Calculate intermediate variables tmp 1 n , tmp 2 n and tmp 3 n : After determining the sector number of the converter, the action time of the first and second effective vectors is determined according to the following correspondence. T xn and T yn : in, n The value can be 1 or 2; n When =1, tmp 1 n , tmp 2 n and tmp 3 n All of these are intermediate variables in the first transformer. U α1 and U β1 These are the rotating voltage components of the first converter. U αβ1 of α , β Axial components; n= At 2 o'clock, tmp 1 n , tmp 2 n and tmp 3 n All of these are intermediate variables in the second transformer. U α2 and U β2 These are the rotating voltage components of the second converter. U αβ2 of α , β Axial components.

5. The voltage modulation method for a switched reluctance motor based on effective vector as described in claim 3, characterized in that, In step (S3), the remaining time in the current period is calculated using the zero vector. U When filling in 0, in step (S22), ; Where, zero vector U 0 represents the vector when all three switches on the bridge arms are at a low level. T s The switching cycle.

6. The voltage modulation method for a switched reluctance motor based on effective vector as described in claim 3, characterized in that, In step (S3), the remaining time in the current period is calculated using the zero vector. U 7. When filling, in step (S22), the correction amount is calculated as follows: T z1 and T z2 : When the first converter is located in sector I, III or V ; When the first converter is located in sector II, IV or VI ; Where, zero vector U 7 represents the vector when all three switches on the bridge arms are at a high level. T s The switching cycle.

7. The voltage modulation method for a switched reluctance motor based on effective vector as described in claim 3, characterized in that, In step (S23), the correction amount is used. T z1 and T z2 Regarding the duration of action T x1 , T y1 , T x2 and T y2 Make corrections, including: Determine the sector where the first converter is located. When the first converter is located in sector I, III, or V, correct it as follows: ； When the first converter is located in sector II, IV, or VI, it shall be corrected as follows: 。 8. A voltage modulation device for a switched reluctance motor based on effective vector, characterized in that, include: The coordinate transformation module is used to acquire the rotor electrical angle of the switched reluctance motor during the current switching cycle. θ e Voltage reference value in synchronous rotating coordinate system u dq0 * After coordinate transformation, the rotating voltage component of the switched reluctance motor is obtained. u αβ and zero-sequence voltage component u z ; Winding voltage modulation module, used for rotating voltage component u αβ By decomposition, the rotational voltage components of the first and second converters in the open-winding motor driver of the switched reluctance motor are obtained. U αβ1 and U αβ2 And calculate the duration of the first effective vector and the second effective vector of the first converter within the current switching cycle. T' x1 and T' y1 And the action time of the first and second effective vectors of the second converter. T' x2 and T' y2 This enables the two converters to achieve zero-sequence voltage components. u z The modulation, and the output rotating voltage components are respectively U αβ1 and U αβ2 The first effective vector is the common-mode voltage amplitude. U dc / 3 effective vector, the second effective vector is the one that generates a common-mode voltage amplitude of 2* U dc / 3 effective vector; U dc This is the DC bus voltage; The duty cycle calculation module is used to calculate the duty cycle based on the duration of action. T' x1 , T' y1 , T' x2 and T' y2 Calculate the duty cycle of each bridge arm in the two converters during the current switching cycle, and fill the remaining time using a single zero vector; And a carrier comparison module, used to determine the switching signal of each bridge arm in the two converters according to the duty cycle, and input it to the open winding motor driver to complete the voltage modulation in the current switching cycle.

9. A switched reluctance motor system, characterized in that, include: A switched reluctance motor and its open-winding motor driver, and the voltage modulation device for a switched reluctance motor based on effective vector as described in claim 8.

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