A variable vector ensemble modulation method for driving a five-phase open-winding current source inverter

Abstract

A variable vector set modulation method for a current-source inverter driving a five-phase open-winding circuit, belonging to the field of motor control, addresses the problems of unclear vector space mapping principles and difficulty in independently controlling the fundamental and third harmonic currents in current-source inverters driving five-phase open-winding circuits. The method involves: retaining a simplified vector space containing only magnitude and magnitude vectors; based on the vector co-occurrence relationship between the fundamental and third harmonic spaces; directly calculating the action time of four adjacent vectors in the same sector according to the amplitude and angle of the fundamental and third harmonic current commands; replacing vectors with action times less than zero by using complementary vectors of equal amplitude and opposite direction to replace the original vectors with action times less than zero; and maintaining the ampere-second product unchanged by taking the opposite of the vector time and ensuring it is greater than zero, thereby guaranteeing the effectiveness of the vector modulation algorithm.

Description

Technical Field

[0001] This invention relates to a variable vector set modulation method for driving a five-phase open-winding current source inverter, belonging to the field of motor control. Background Technology

[0002] As a core power unit in aerospace, marine propulsion, and new energy vehicle applications, the operational quality and reliability of motor systems are closely related to national and public safety. Multiphase motors, with their high redundancy and fault tolerance, make the research on multiphase motor drive control technology based on high-reliability driver topologies of great significance. Traditional multiphase motors generally use voltage source inverter topologies for drive control. However, the high-frequency voltage pulses output by these inverters contain a large number of voltage harmonics and are accompanied by a high voltage change rate du / dt. This can lead to increased motor current harmonics, affecting torque quality, and can also adversely affect the system's electromagnetic compatibility performance, as well as the lifespan of insulation and bearings. Furthermore, voltage source inverters use capacitor energy storage, which has limitations in terms of temperature resistance, environmental adaptability, and lifespan, becoming a bottleneck factor restricting system reliability. In recent years, scholars both domestically and internationally have proposed using current-source inverter topologies to address bottlenecks in traditional systems. Current-source inverters, employing inductors as energy storage devices, offer significant advantages in temperature resistance, environmental adaptability, and lifespan. Furthermore, as an AC current source, current-source inverters possess higher output impedance and current regulation accuracy, enabling them to adapt to drastic changes in load impedance while ensuring high-quality current output. Applying current-source inverters to drive multiphase motors further leverages the fault-tolerant capabilities of redundant bridge arms, thereby fully utilizing the reliability advantages of this topology. However, current research on current-source inverters driving five-phase open-winding motors is relatively limited. Related control technologies suffer from unclear vector space mapping principles and difficulties in independently controlling the fundamental and third harmonic currents, resulting in challenges in implementing vector modulation methods and high motor current harmonic losses. Summary of the Invention

[0003] To address the problems of unclear vector space mapping principles and difficulty in independently controlling the fundamental and third harmonic currents in current-source inverters driving five-phase open-winding circuits, this invention provides a variable vector ensemble modulation method for such inverters.

[0004] The present invention discloses a variable vector set modulation method for driving a five-phase open-winding current source inverter, wherein the inverter includes a DC current source I. p Bus inductance L dc and AC power supply unit, wherein the AC power supply unit includes S ip and S in The system consists of six pairs of switching devices, i = 1, 2, 3, 4, 5, 6, and each pair is connected to one of the five-phase windings of the motor. sa,w sb ,w sc ,w sd ,w se Five output ports connected at both ends, diode D ip and D in respectively with S ip and S in Series connection ensures the uniformity of the current direction in the busbars; S ip and S in Complementary conduction ensures continuous bus current, with a total of 2 6 =64 switch states;

[0005] The modulation method is a variable vector set modulation method using adjacent four vectors and their complementary vectors:

[0006] Current vector I in fundamental space 1st for:

[0007]

[0008] Where α = 0.4π, c 1st ψ1 is the fundamental frequency vector amplitude coefficient, i is the fundamental frequency vector angle, and i is the fundamental frequency vector amplitude coefficient. dc Bus current;

[0009] Keep c 1st =0.76 and 0.47, the simplified fundamental vector space of the two vectors, large and small, is divided into 10 uniform sectors in a counterclockwise direction;

[0010] The accompanying third harmonic space current vector I 3rd for:

[0011]

[0012] Each sector contains two adjacent large vectors and two small vectors. First, the duration of action of the four adjacent vectors in the k-th sector is calculated based on the fundamental and third harmonic current commands.

[0013]

[0014] In the formula I ref1 ,I ref3 —Command amplitude of fundamental and third harmonic currents;

[0015] θ1, θ3 — command angles for the fundamental and third harmonic currents;

[0016] T 2k-1 ,T 2k+1 —The duration of action of two adjacent large vectors in the k-th sector;

[0017] T 2k ,T2k+2 —The time of action of two adjacent small vectors in the k-th sector;

[0018] T s —Switching cycle;

[0019] k = 1, 2, ..., 10;

[0020] When the fundamental current command approaches the boundaries of each sector, i.e., θ1 = (0.2k - 0.3)π or θ1 = (0.2k - 0.1)π, T 2k-1 ,T 2k+1 ,T 2k ,T 2k+2 If at least one invalid calculation result not greater than zero exists, vector modulation cannot be completed normally;

[0021] When a certain vector I p When the duration of action is less than zero, p = 1, 2, ..., 20, utilizing I p Complementary vectors I with equal amplitude and opposite direction q Replace it, keeping the ampere-second product unchanged, and then vector I p The opposite of the action time is taken as vector I. q The duration of action is sufficient to complete vector modulation.

[0022] Preferably, p and q satisfy the following relationship:

[0023]

[0024] Preferably, the switching state of the inverter is represented by a binary combination S. cmb =(S6,S5,S4,S3,S2,S1), S i S represents ip and S in The combination of switching devices, S i =1 indicates S ip On, S in Off; S i =0 indicates S ip Shutdown, S in Conduction;

[0025] When S cmb When S = (0,0,0,0,0,0,0) or (1,1,1,1,1,1,1), the bus current only flows through the series arm of the lower or upper branch and does not flow through any phase winding, corresponding to two zero vectors. cmb When the current is not equal to (0,0,0,0,0,0) and (1,1,1,1,1,1), the bus current will flow through the winding and generate effective excitation, corresponding to 62 effective vectors.

[0026] Preferably, the 62 effective vectors in the fundamental space have 9 different amplitudes, where c 1st The number of vectors with values ​​of 0.29, 0.4, 0.47, and 0.76 is 10; c 1st The number of vectors for the values ​​0.15, 0.49, 0.62, 0.86, and 1.05 are 6, 2, 8, 4, and 2 respectively; only c is retained. 1st =0.47 and c 1st =0.76 and a total of 20 large and small vectors constitute a simplified fundamental vector space. Each sector contains two adjacent large vectors and two small vectors. The third harmonic vector space is associated with the fundamental vector space, and the simplified third harmonic vector space contains the third harmonic amplitude coefficient c. 3rd =0.47 and c 3rd =0.76 and a total of 20 large and small vectors, each sector contains two adjacent large vectors and two small vectors;

[0027] Fundamental wave spatial angle ψ1=θ、c 1st The large vector of 0.76 corresponds to the third harmonic spatial angle ψ3 = 3θ, c 3rd =0.47, where θ represents the angle from 0 to 2π;

[0028] Fundamental wave spatial angle ψ1=θ、c 1st The small vector of 0.47 corresponds to the third harmonic spatial angle ψ3 = 3θ + π, c 3rd A large vector with a value of 0.76.

[0029] Preferably, the fundamental and third harmonic current commands are executed according to the following formula:

[0030]

[0031] The action time of the four adjacent vectors in the k-th sector is obtained:

[0032]

[0033] Wherein, (0.2k-0.3)π≤θ1≤(0.2k-0.1)π.

[0034] Preferably, the AC power supply unit further includes a diode D. 1p To D 6p Diode D 1n To D 6n Flying capacitor C f1 To C f6 and filter capacitor C sa To C se ;

[0035] The AC power supply unit is divided into two parallel branches, upper and lower.

[0036] The upper branch road runs from left to right according to D 1p ,S 1p D 2p ,S 2p D 3p ,S 3p D 4p ,S 4p D 5p ,S 5p D 6p ,S 6p The order of the chains is connected, and the lower branches are arranged from left to right according to S. 1n D 1n ,S 2n D 2n ,S 3n D 3n ,S 4n D 4n ,S 5n D 5n ,S 6n D 6n The diodes are connected in series in sequence, with the conduction direction opposite to that of the anti-parallel diodes of the switching devices; the five output ports are located between adjacent switching devices in the upper and lower branches, with the j-th output port located at S. ip negative electrode and S (i+1)n The inverter is located between the positive and negative terminals, where j = i, j = 1, 2, ..., 5;

[0037] S in negative electrode and S ip The positive terminals are connected by a flying capacitor.

[0038] The beneficial effects of this invention are as follows: This invention provides a variable vector set modulation method for driving a five-phase open-winding current-source inverter. It reveals the vector space mapping principle of this type of topology, presents a simplified vector space containing only large and small vectors, ensuring high bus utilization while reducing control complexity. The method analyzes the vector co-occurrence relationship between the fundamental and third harmonic currents, and proposes a vector modulation method based on variable vector sets. Utilizing complementary vectors of equal amplitude and opposite direction, it solves the problems of invalid vector time calculation results and difficulty in independently controlling the fundamental and third harmonic currents in the vicinity of sector boundaries in traditional adjacent four-vector modulation methods. This enables precise suppression or injection of the third harmonic current in a five-phase motor, which is beneficial for improving the efficiency and torque density of the motor system. Therefore, this invention is highly applicable to applications in aerospace, marine propulsion, and new energy vehicles. Attached Figure Description

[0039] Figure 1 This is the current source inverter topology that drives a five-phase open-winding inverter corresponding to the vector modulation method described in this invention;

[0040] Figure 2 It is the fundamental vector space of the vector modulation method described in this invention;

[0041] Figure 3 It is the simplified fundamental vector space and third harmonic vector space of the vector modulation method described in this invention; wherein Figure 3 (a) is the simplified fundamental vector space. Figure 3 (b) is the simplified third harmonic vector space;

[0042] Figure 4 This is a vector composite diagram showing the invalidity of the adjacent four-vector modulation method corresponding to the first sector example of the vector modulation method described in this invention; wherein... Figure 4 (a) is the vector composite diagram of the fundamental current; Figure 4 (b) is the vector composition diagram of the third harmonic current;

[0043] Figure 5 The vector modulation method of the present invention replaces the first sector vector I1 with the complementary vector I. 11 The vector synthesis diagram of the variable vector set modulation method corresponding to the example, where Figure 5 (a) is the vector composite diagram of the fundamental current; Figure 5 (b) Vector synthesis diagram of third harmonic current. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0047] Specific Implementation Method 1: The following is combined with... Figures 1 to 5 This embodiment describes a variable vector set modulation method for driving a five-phase open-winding current source inverter. This method is based on... Figure 1 The inverter shown is used for this purpose, and the inverter includes a DC current source I. p Bus inductance L dc and AC power supply unit, wherein the AC power supply unit includes S ip and S inThe combination consists of 6 pairs of switching devices, i = 1, 2, 3, 4, 5, 6, and diode D. 1p To D 6p Diode D 1n To D 6n Flying capacitor C f1 To C f6 and filter capacitor C sa To C se ; and respectively with the five-phase windings of the motor w sa ,w sb ,w sc ,w sd ,w se Five output ports connected at both ends, diode D ip and D in respectively with S ip and S in Series connection ensures the single direction of bus current;

[0048] The AC power supply unit is divided into two parallel branches, upper and lower.

[0049] The upper branch road runs from left to right according to D 1p ,S 1p D 2p ,S 2p D 3p ,S 3p D 4p ,S 4p D 5p ,S 5p D 6p ,S 6p The order of the chains is connected, and the lower branches are arranged from left to right according to S. 1n D 1n ,S 2n D 2n ,S 3n D 3n ,S 4n D 4n ,S 5n D 5n ,S 6n D 6n The diodes are connected in series in sequence, with the conduction direction opposite to that of the anti-parallel diodes of the switching devices; the five output ports are located between adjacent switching devices in the upper and lower branches, with the j-th output port located at S. ip negative electrode and S (i+1)n The inverter is located between the positive and negative terminals, where j = i, j = 1, 2, ..., 5;

[0050] S in negative electrode and S ip The positive terminals are connected by a flying capacitor.

[0051] S ip and S in Complementary conduction ensures continuous bus current, with a total of 2 6 =64 switch states;

[0052] The switching state of the inverter is represented by the binary combination S. cmb =(S6,S5,S4,S3,S2,S1), S i S represents ip and S in The combination of switching devices, S i =1 indicates S ip On, S in Off; S i =0 indicates S ip Shutdown, S in Conduction;

[0053] When S cmb When S = (0,0,0,0,0,0,0) or (1,1,1,1,1,1,1), the bus current only flows through the series arm of the lower or upper branch and does not flow through any phase winding, corresponding to two zero vectors. cmb When the current is not equal to (0,0,0,0,0,0) and (1,1,1,1,1,1), the bus current will flow through the winding and generate effective excitation, corresponding to 62 effective vectors.

[0054] Flowing through w sa to w se The instantaneous currents are expressed as i sa to i se The value may be equal to i dc Or 0, according to the five-phase Clarke transform, the fundamental space current vector is expressed in complex vector form: Where α = 0.4π, c 1st ψ1 is the fundamental wave vector amplitude coefficient, and ψ1 is the fundamental wave vector angle.

[0055] S cmb With c 1st The correspondence between ψ1 and ψ2 is given in the table below, which allows us to plot the fundamental vector space of the inverter. The 62 effective vectors have 9 different amplitudes, and the number of vectors with different amplitudes is not entirely equal. Among them, c... 1st The number of vectors with values ​​of 0.29, 0.4, 0.47, and 0.76 is 10; c 1st The remaining five vectors with values ​​of 0.15, 0.49, 0.62, 0.86, and 1.05 have numbers of 6, 2, 8, 4, and 2 respectively. Considering the symmetry of the vector space, we first retain the four vectors with a number of 10; secondly, we consider the vector c among the four vectors. 1stThe vector direction with a value of 0.4 does not coincide with the other three vector directions, so it is deleted; further, delete c. 1st The minimum vector of 0.29 ensures high busbar utilization. This results in a vector containing only c. 1st =0.76 and 0.47, the simplified fundamental vector space of the two vectors, large and small, is divided into 10 uniform sectors in a counterclockwise direction. See [reference needed]. Figure 3 .

[0056]

[0057]

[0058] The current vector in the third harmonic space is represented in complex vector form: Same S cmb Corresponding to different I 1st with I 3rd The two have a co-occurring relationship: the fundamental spatial angle ψ1 = θ, c 1st The large vector of 0.76 corresponds to the third harmonic spatial angle ψ3 = 3θ, c 3rd =0.47 small vector; fundamental wave spatial angle ψ1 = θ, c 1st The small vector of 0.47 corresponds to the third harmonic spatial angle ψ3 = 3θ + π, c 3rd =0.76, where θ represents a spatial angular variable from 0 to 2π.

[0059] Each sector contains two adjacent large vectors and two small vectors. The duration of action of the four adjacent vectors is first calculated directly based on the fundamental and third harmonic current commands. (See the principle below.) Figure 4 The calculation method for sector 1 is as follows:

[0060]

[0061] Solving

[0062]

[0063] Similarly, the action time of the four adjacent vectors in the k-th sector can be obtained as follows: k = 1, 2, ..., 10, (0.2k - 0.3)π ≤ θ1 ≤ (0.2k - 0.1)π.

[0064]

[0065] In the formula I ref1 ,I ref3 —Command amplitude of fundamental and third harmonic currents;

[0066] θ1, θ3 — command angles for the fundamental and third harmonic currents;

[0067] T1, T3 — the time of action of two adjacent large vectors in sector 1;

[0068] T2, T4 — the time of action of two adjacent small vectors in sector 1;

[0069] T 2k-1 ,T 2k+1 —The duration of action of two adjacent large vectors in the k-th sector;

[0070] T 2k ,T 2k+2 —The time of action of two adjacent small vectors in the k-th sector;

[0071] T s —Switch cycle.

[0072] The fundamental and third harmonic current commands have independent amplitude and angle relationships. In the first sector, when the fundamental current command angle θ1 is close to 0.1π, it can be seen from equation (2) that the first term in the expressions for T1 and T2 is close to zero, and can be approximately expressed as follows: Therefore, T1·T2≤0. Similarly, when θ1 is close to -0.1π, T3·T4≤0. The above analysis shows that for the adjacent four-vector modulation method, when the fundamental current command is close to the boundaries of each sector, at least one vector time calculation result is not greater than zero, which is an invalid result. Therefore, it is difficult to accurately and independently synthesize the fundamental and third harmonic current commands using the adjacent four-vector modulation method.

[0073] This invention proposes a variable vector set modulation method, which, for a certain vector I among four adjacent vectors... p In cases where the time calculation result is invalid, p = 1, 2, ..., 20, utilize I p Complementary vectors I with equal amplitude and opposite direction q Replace it, keeping the ampere-second product unchanged, and then vector I p The opposite of the action time is taken as vector I. q The interaction time is ensured to be greater than zero for all vector interactions, thus completing vector modulation. See the principle below. Figure 5 where p and q satisfy the following relationship:

[0074]

[0075] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A variable vector ensemble modulation method for driving a five-phase open-winding current source inverter, characterized in that, The inverter includes a DC current source I p Bus inductance L dc and AC power supply unit, wherein the AC power supply unit includes S ip and S in The system consists of six pairs of switching devices, i = 1, 2, 3, 4, 5, 6, and each pair is connected to one of the five-phase windings of the motor. sa ,w sb ,w sc ,w sd ,w se Five output ports connected at both ends, diode D ip and D in respectively with S ip and S in Series connection ensures the uniformity of the current direction in the busbars; S ip and S in Complementary conduction ensures continuous bus current, with a total of 2 6 =64 switch states; The modulation method is a variable vector set modulation method using adjacent four vectors and their complementary vectors: Current vector I in fundamental space 1st for: Where α = 0.4π, c 1st ψ is the fundamental frequency vector amplitude coefficient. 1 Let i be the fundamental frequency vector angle. dc Bus current; Keep c 1st =0.76 and 0.47, the simplified fundamental vector space of the two vectors, large and small, is divided into 10 uniform sectors in a counterclockwise direction; The accompanying third harmonic space current vector I 3rd for: Each sector contains two adjacent large vectors and two small vectors. First, the duration of action of the four adjacent vectors in the k-th sector is calculated based on the fundamental and third harmonic current commands. In the formula I ref1 ,I ref3 —Command amplitude of fundamental and third harmonic currents; θ1, θ3 — command angles for the fundamental and third harmonic currents; T 2k-1 ,T 2k+1 —The duration of action of two adjacent large vectors in the k-th sector; T 2k ,T 2k+2 —The time of action of two adjacent small vectors in the k-th sector; T s —Switching cycle; k＝1,2,…,10； When the fundamental current command approaches the boundaries of each sector, i.e., θ1 = (0.2k - 0.3)π or θ1 = (0.2k - 0.1)π, T 2k-1 ,T 2k+1 ,T 2k ,T 2k+2 If at least one invalid calculation result not greater than zero exists, vector modulation cannot be completed normally; When a certain vector I p When the duration of action is less than zero, p = 1, 2, ..., 20, utilizing I p Complementary vectors I with equal amplitude and opposite direction q Replace it, keeping the ampere-second product unchanged, and then vector I p The opposite of the action time is taken as vector I. q The duration of action is sufficient to complete vector modulation; p and q satisfy the following relationship: The switching state of the inverter is represented by the binary combination S. cmb =(S6,S5,S4,S3,S2,S1), S i S represents ip and S in The combination of switching devices, S i =1 indicates S ip On, S in Off; S i =0 indicates S ip Shutdown, S in Conduction; When S cmb When S = (0,0,0,0,0,0) or (1,1,1,1,1,1,1), the bus current only flows through the series bridge arm of the lower or upper branch and will not flow through any phase winding, corresponding to two zero vectors; when S cmb When ≠(0,0,0,0,0,0) and (1,1,1,1,1,1), the bus current will flow through the winding and generate effective excitation, corresponding to 62 effective vectors; The 62 effective vectors in the fundamental space have 9 different amplitudes, among which c 1st The number of vectors with values ​​of 0.29, 0.4, 0.47, and 0.76 is 10; c 1st The number of vectors for the values ​​0.15, 0.49, 0.62, 0.86, and 1.05 are 6, 2, 8, 4, and 2 respectively; only c is retained. 1st =0.47 and c 1st =0.76 and a total of 20 large and small vectors constitute a simplified fundamental vector space. Each sector contains two adjacent large vectors and two small vectors. The third harmonic vector space is associated with the fundamental vector space, and the simplified third harmonic vector space contains the third harmonic amplitude coefficient c. 3rd =0.47 and c 3rd =0.76 and a total of 20 large and small vectors, each sector contains two adjacent large vectors and two small vectors; Fundamental wave spatial angle ψ 1 =θ, c 1st The large vector of 0.76 corresponds to the third harmonic spatial angle ψ. 3 =3θ, c 3rd =0.47, where θ represents the angle from 0 to 2π; Fundamental wave spatial angle ψ 1 =θ, c 1st The small vector of 0.47 corresponds to the third harmonic spatial angle ψ. 3 =3θ+π, c 3rd A large vector with a value of 0.

76.

2. The variable vector set modulation method for driving a five-phase open-winding current source inverter according to claim 1, characterized in that, According to the fundamental and third harmonic current commands, follow the formula below. The action time of the four adjacent vectors in the k-th sector is obtained: Wherein, (0.2k-0.3)π≤θ1≤(0.2k-0.1)π.

3. The variable vector set modulation method for driving a five-phase open-winding current source inverter according to claim 1, characterized in that, The AC power supply unit also includes diode D. 1p To D 6p diode D 1n To D 6n Flying capacitor C f1 To C f6 and filter capacitor C sa To C se ; The AC power supply unit is divided into two parallel branches, upper and lower. The upper branch road runs from left to right according to D 1p ,S 1p D 2p ,S 2p D 3p ,S 3p D 4p ,S 4p D 5p ,S 5p D 6p ,S 6p The order of the chains is connected, and the lower branches are arranged from left to right according to S. 1n D 1n ,S 2n D 2n ,S 3n D 3n ,S 4n D 4n ,S 5n D 5n ,S 6n D 6n The diodes are connected in series in sequence, with the conduction direction opposite to that of the anti-parallel diodes of the switching devices; the five output ports are located between adjacent switching devices in the upper and lower branches, with the j-th output port located at S. ip negative electrode and S (i+1)n The inverter is located between the positive and negative terminals, where j = i, j = 1, 2, ..., 5; S in negative electrode and S ip The positive terminals are connected by a flying capacitor.

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