Variable vector set modulation method for current source inverter for driving five-phase open winding

Abstract

The invention discloses a variable vector set modulation method for a current source type inverter for driving a five-phase open winding, belongs to the field of motor control, and aims to solve the problems that the vector space mapping principle of the current source type inverter for driving the five-phase open winding is not clear, and fundamental wave and third harmonic current are difficult to independently control. The method comprises the steps that a simplified vector space only containing a large vector and a small vector is reserved, the action time of adjacent four vectors in the same sector is directly calculated according to the amplitude and angle of fundamental wave and third harmonic current instructions on the basis of the vector associated relation of fundamental wave and third harmonic space, the vectors with the action time smaller than zero are replaced, and the vector space with the action time smaller than zero is obtained. An original vector with action time smaller than zero is replaced with a constant-amplitude and reverse complementary vector, the opposite number can be taken from the vector time by keeping the ampere-second product unchanged, and the vector time is larger than zero, so that the effectiveness of a vector modulation algorithm is guaranteed.

Description

Technical Field

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

[0002] As the core power device in aerospace, ship propulsion, new energy vehicles and other application fields, the operating quality and reliability of the motor system are closely related to the national and people's livelihood security. Multi-phase motors have high redundancy and high fault tolerance. It is of great significance to study the multi-phase motor drive control technology based on high-reliability driver topology. Traditional multi-phase motors generally use voltage source inverter topology for drive control. However, the high-frequency voltage pulses output by them contain a large number of voltage harmonics and are accompanied by a high voltage change rate du / dt. On the one hand, it will cause the motor current harmonics to increase and affect the torque quality. On the other hand, it will have an adverse effect on the electromagnetic compatibility performance of the system and the service life of insulation and bearings. In addition, the voltage source inverter uses capacitor energy storage, which has limitations in temperature resistance, environmental adaptability and service life, becoming a bottleneck factor limiting the reliability of the system. In recent years, scholars at home and abroad have proposed using current source inverter topology to solve the bottleneck problem in traditional systems. Current source inverters use inductors as energy storage devices, which have significant advantages in temperature resistance, environmental adaptability, and service life. In addition, as an AC current source, current source inverters have high output impedance and current regulation accuracy, can adapt to drastic changes in load impedance and ensure high-quality current output capabilities. Applying current source inverters to drive multi-phase motors can further combine the fault tolerance of redundant bridge arms, thereby giving full play to the reliability advantages of this topology. For current source inverters that drive five-phase open windings, current research results are relatively limited. The relevant control technologies have problems such as unclear vector space mapping principles and difficulty in independent control of fundamental and third harmonic currents, which makes the vector modulation method difficult to implement and high harmonic losses in motor currents. Summary of the invention

[0003] In order to solve the problem that the vector space mapping principle of a current source inverter driving a five-phase open winding is unclear and the fundamental and third harmonic currents are difficult to control independently, the present invention provides a variable vector set modulation method for a current source inverter driving a five-phase open winding.

[0004] The invention discloses a method for modulating a current source inverter for driving a five-phase open winding. The inverter includes a DC current source I p , bus inductance L dc and an AC power supply unit, wherein the AC power supply unit comprises S ip and S in The 6 pairs of switch components are composed of i=1,2,3,4,5,6, and are respectively connected to the five-phase windings w of the motor. sa,w sb ,w sc ,w sd ,w se The 5 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; S ip and S in Complementary conduction ensures the continuity of bus current. There are 2 6 =64 switch states;

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

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

[0007]

[0008] Where, α = 0.4π, c 1st is the fundamental wave vector amplitude coefficient, ψ 1 is the fundamental wave vector angle, i dc is the bus current;

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

[0010] The current vector I in the associated third harmonic space 3rd for:

[0011]

[0012] Each sector contains two adjacent large vectors and two small vectors. First, the action time of the four adjacent vectors in the kth sector is calculated according to the fundamental and third harmonic current instructions:

[0013]

[0014] Where I ref1 ,I ref3 ——Fundamental and third harmonic current command amplitude;

[0015] θ 1 ,θ 3 ——Fundamental and third harmonic current command angles;

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

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

[0018] T s ——Switching cycle;

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

[0020] When the fundamental current command approaches the boundary of each sector, that is, θ 1 =(0.2k-0.3)πorθ 1 =(0.2k-0.1)π, T 2k-1 ,T 2k+1 ,T 2k ,T 2k+2 There is at least one invalid calculation result not greater than zero, and vector modulation cannot be completed normally;

[0021] When a vector I p When the action time is less than zero, p=1,2,…,20, using I p Complementary vectors of equal magnitude and opposite direction I q Replace it, keep the ampere-second product unchanged and change the vector I p The opposite of the action time is taken as vector I q action time 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 =(S 6 ,S 5 ,S 4 ,S 3 ,S 2 ,S 1 ), S i Indicates S ip and S in The switch device combination, S i =1 means S ip On, S in Shutdown; S i =0 means S ip Shutdown, S in Conductivity;

[0025] When S cmb=(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 branch or the upper branch, and does not flow through any phase winding, corresponding to 2 zero vectors. 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.

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

[0027] Fundamental wave spatial angle ψ 1 =θ、c 1st =0.76 corresponds to the third harmonic space angle ψ 3 =3θ, c 3rd = A small vector of 0.47, θ represents an angle from 0 to 2π;

[0028] Fundamental wave spatial angle ψ 1 =θ、c 1st =0.47 corresponds to the third harmonic space angle ψ 3 =3θ+π, c 3rd =A large vector of 0.76.

[0029] Preferably, according to the fundamental wave and the third harmonic current command,

[0030]

[0031] The solution is the action time of the four adjacent vectors in the kth sector:

[0032]

[0033] Where, (0.2k-0.3)π≤θ 1≤(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] From left to right on the upper branch, follow 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 lower branch is connected in series 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 conduction direction of the diode is opposite to the conduction direction of the anti-parallel diode of the switch device; the five output ports are set between the adjacent switch devices of the upper branch and the lower branch, and the jth output port is located at S ip The negative electrode and S (i+1)n The positive pole of is the inverter, j=i, j=1,2,…,5;

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

[0038] Beneficial effects of the present invention: The variable vector set modulation method of the current source inverter driving the five-phase open winding of the present invention reveals the vector space mapping principle of this type of topology, and provides a simplified vector space containing only large and small vectors, which reduces the control complexity while ensuring a high bus utilization rate. The vector association relationship between the fundamental wave and the third harmonic space is analyzed, and a vector modulation method based on a variable vector set is proposed. By using equal-amplitude and reverse complementary vectors, the problem that the vector time calculation results of the traditional adjacent four-vector modulation method are invalid in the area near the sector boundary and it is difficult to independently control the fundamental wave and the third harmonic current is solved. The third harmonic current of the five-phase motor can be accurately suppressed or injected, which is beneficial to improving the efficiency and torque density of the motor system. Therefore, the present invention is very suitable for application fields such as aerospace, ship propulsion, and new energy vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The vector modulation method of the present invention corresponds to the current source inverter topology driving the five-phase open winding;

[0040] Figure 2 is the fundamental wave vector space of the vector modulation method of the present invention;

[0041] Figure 3 is the simplified fundamental wave vector space and the third harmonic vector space of the vector modulation method of the present invention; wherein Figure 3 (a) is the simplified fundamental wave vector space, Figure 3 (b) is the simplified third harmonic vector space;

[0042] Figure 4 is a vector synthesis diagram of invalid situations of adjacent four vector modulation methods corresponding to the first sector example of the vector modulation method described in the present invention; wherein Figure 4 (a) is the fundamental current vector synthesis diagram; Figure 4 (b) is the third harmonic current vector synthesis diagram;

[0043] Figure 5 The first sector vector I of the vector modulation method of the present invention is 1 Replaced by complementary vector I 11 Vector synthesis diagram of the variable vector set modulation method corresponding to the example, where Figure 5 (a) is the fundamental current vector synthesis diagram; Figure 5 (b) Third harmonic current vector synthesis diagram. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0046] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0047] Specific implementation method 1: The following is combined Figures 1 to 5 The present embodiment describes a method for modulating a current source inverter vector set to drive a five-phase open winding. The method is based on Figure 1 The inverter shown in FIG. 1 includes a DC current source I p , bus inductance L dc and an AC power supply unit, wherein the AC power supply unit comprises S ip and S in Composed of 6 pairs of switch devices, i = 1, 2, 3, 4, 5, 6, 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 winding w of the motor sa ,w sb ,w sc ,w sd ,w se The 5 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] From left to right on the upper branch, follow 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 lower branch is connected in series 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 conduction direction of the diode is opposite to the conduction direction of the anti-parallel diode of the switch device; the five output ports are set between the adjacent switch devices of the upper branch and the lower branch, and the jth output port is located at S ip The negative electrode and S (i+1)n The positive pole of is the inverter, j=i, j=1,2,…,5;

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

[0051] S ip and S in Complementary conduction ensures the continuity of bus current. There are 2 6 =64 switch states;

[0052] The switching state of the inverter is represented by the binary combination S cmb =(S 6 ,S 5 ,S 4 ,S 3 ,S 2 ,S 1 ), S i Indicates S ip and S in The switch device combination, S i =1 means S ip On, S in Shutdown; S i =0 means S ip Shutdown, S in Conductivity;

[0053] When S cmb =(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 branch or the upper branch, and does not flow through any phase winding, corresponding to 2 zero vectors. cmbWhen ≠(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 sa tow se The instantaneous current is represented as i sa to i se , the value may be equal to i dc Or 0, according to the five-phase Clarke transformation, the fundamental space current vector is expressed as a complex vector form: Where, α = 0.4π, c 1st is the fundamental wave vector amplitude coefficient, ψ 1 is the fundamental wave vector angle.

[0055] S cmb With c 1st , 1 The corresponding relationship is given in the table below, so that the fundamental wave vector space of the inverter can be drawn. The 62 effective vectors have 9 different amplitudes, and the number of vectors with different amplitudes is not completely equal. Among them, c 1st = 0.29, 0.4, 0.47, 0.76, the number of vectors is 10; c 1st =0.15, 0.49, 0.62, 0.86, 1.05, the numbers of the other five vectors are 6, 2, 8, 4, 2. Considering the symmetry of the vector space, first retain the four vectors with a total number of 10; secondly, consider the four vectors c 1st = 0.4 does not coincide with the other three vector directions, so delete it. Further delete c 1st =0.29, ensuring a high bus utilization rate. 1st = 0.76 and 0.47, and the simplified fundamental wave vector space of the large and small vectors is divided into 10 uniform sectors in a counterclockwise direction. Figure 3 .

[0056]

[0057]

[0058] The current vector in the third harmonic space is expressed as a complex vector form: Same S cmb Corresponding to different I 1st with I 3rd , the two have a companion relationship: the fundamental wave spatial angle ψ 1 =θ、c 1st =0.76 corresponds to the third harmonic space angle ψ 3 =3θ, c3rd = small vector of 0.47; fundamental wave spatial angle ψ 1 =θ、c 1st =0.47 corresponds to the third harmonic space angle ψ 3 =3θ+π, c 3rd = 0.76, θ represents a certain spatial angle variable from 0 to 2π.

[0059] Each sector contains two adjacent large vectors and two small vectors. First, the action time of the adjacent four vectors is directly calculated according to the fundamental wave and the third harmonic current command. For the principle, see Figure 4 , the calculation method of the first sector is as follows:

[0060]

[0061] Solved

[0062]

[0063] Similarly, the action time of the four adjacent vectors in the kth sector is as follows, k = 1, 2, ..., 10, (0.2k-0.3)π≤θ 1 ≤(0.2k-0.1)π.

[0064]

[0065] Where I ref1 ,I ref3 ——Fundamental and third harmonic current command amplitude;

[0066] θ 1 ,θ 3 ——Fundamental and third harmonic current command angles;

[0067] T 1 ,T 3 ——The action time of two adjacent large vectors in the first sector;

[0068] T 2 ,T 4 ——The action time of two adjacent small vectors in the first sector;

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

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

[0071] T s ——Switching 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 θ 1 When it is close to 0.1π, it can be seen from formula (2) that T 1 With T 2 The first term in the expression is close to zero, and can be approximately expressed as So we get T 1 ·T 2 ≤0. Similarly, when θ 1 When it is close to -0.1π, there is T 3 ·T 4 ≤0. The above analysis shows that for the adjacent four-vector modulation method, when the fundamental current command is close to the boundary of each sector, there is at least one vector time whose 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] The present invention proposes a variable vector set modulation method, for a vector I among four adjacent vectors p In the case of invalid time calculation results, p = 1, 2, ..., 20, use the same p Complementary vectors of equal magnitude and opposite direction I q Replace it, keep the ampere-second product unchanged and change the vector I p The opposite of the action time is taken as vector I q Action time, ensure that all vector action time is greater than zero, complete vector modulation, the principle see Figure 5 , where p and q satisfy the following relationship:

[0074]

[0075] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A variable vector set 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 an AC power supply unit, wherein the AC power supply unit comprises S ip and S in The 6 pairs of switch components are composed of i=1,2,3,4,5,6, and are respectively connected to the five-phase windings w of the motor. sa ,w sb ,w sc ,w sd ,w se The 5 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; S ip and S in Complementary conduction ensures the continuity of bus current. There are 2 6 =64 switch states; The modulation method is a variable vector set modulation method using four adjacent vectors and their complementary vectors: Current vector I in fundamental wave space 1st for: Where, α = 0.4π, c 1st is the fundamental wave vector amplitude coefficient, ψ1 is the fundamental wave vector angle, i dc is the bus current; Keep c 1st =0.76 and 0.47, the simplified fundamental wave vector space of two large and small vectors, and divided into 10 uniform sectors in a counterclockwise direction; The current vector I in the associated third harmonic space 3rd for: Each sector contains two adjacent large vectors and two small vectors. First, the action time of the four adjacent vectors in the kth sector is calculated according to the fundamental and third harmonic current instructions: Where I ref1 ,I ref3 ——Fundamental and third harmonic current command amplitude; θ1,θ3——the fundamental and third harmonic current command angles; T 2k-1 ,T 2k+1 ——The action time of two adjacent large vectors in the kth sector; T 2k ,T 2k+2 ——The action time of two adjacent small vectors in the kth sector; T s ——Switching cycle; k＝1,2,…,10； When the fundamental current command is close to the boundary of each sector, that is, θ1=(0.2k-0.3)π or θ1=(0.2k-0.1)π, T 2k-1 ,T 2k+1 ,T 2k ,T 2k+2 There is at least one invalid calculation result not greater than zero, and vector modulation cannot be completed normally; When a vector I p When the action time is less than zero, p=1,2,…,20, using I p Complementary vectors of equal magnitude and opposite direction I q Replace it, keep the ampere-second product unchanged and change the vector I p The opposite of the action time is taken as vector I q action time to complete vector modulation.

2. According to claim 1, a variable vector set modulation method for driving a five-phase open-winding current source inverter, characterized in that: p and q satisfy the following relationship:

3. According to claim 1, a variable vector set modulation method for driving a five-phase open-winding current source inverter, characterized in that: The switching state of the inverter is represented by the binary combination S cmb =(S6,S5,S4,S3,S2,S1), S i Indicates S ip and S in The switch device combination, S i =1 means S ip On, S in Shutdown; S i =0 means S ip Shutdown, S in Conductivity; When S cmb =(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 branch or the upper branch, and does not flow through any phase winding, corresponding to 2 zero vectors. 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.

4. According to claim 3, a variable vector set modulation method for driving a five-phase open-winding current source inverter, characterized in that: The 62 effective vectors in the fundamental wave space have 9 different amplitudes, among which c 1st = 0.29, 0.4, 0.47, 0.76, the number of vectors is 10; c 1st =0.15, 0.49, 0.62, 0.86, 1.05, the numbers of the other five vectors are 6, 2, 8, 4, 2 respectively; only c is retained 1st = 0.47 and c 1st =0.76 and the total number of large and small vectors is 20, forming a simplified fundamental wave vector space. Each sector contains two adjacent large vectors and two small vectors. The third harmonic vector space has a companion relationship with the fundamental wave vector space. There is a third harmonic amplitude coefficient c in the simplified third harmonic vector space. 3rd = 0.47 and c 3rd =0.76 and the total number of large and small vectors is 20, and each sector contains two adjacent large vectors and two small vectors; Fundamental wave spatial angle ψ1 = θ, c 1st = 0.76 corresponds to the third harmonic space angle ψ3 = 3θ, c 3rd = A small vector of 0.47, θ represents an angle from 0 to 2π; Fundamental wave spatial angle ψ1 = θ, c 1st =0.47 corresponds to the third harmonic space angle ψ3 = 3θ + π, c 3rd =A large vector of 0.

76.

5. 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 wave and third harmonic current instructions, press the formula The solution is the action time of the four adjacent vectors in the kth sector: Among them, (0.2k-0.3)π≤θ1≤(0.2k-0.1)π.

6. A 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 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 ; The AC power supply unit is divided into two parallel branches, upper and lower; From left to right on the upper branch, follow 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 lower branch is connected in series 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 conduction direction of the diode is opposite to the conduction direction of the anti-parallel diode of the switch device; the five output ports are set between the adjacent switch devices of the upper branch and the lower branch, and the jth output port is located at S ip The negative electrode and S (i+1)n The positive pole of is the inverter, j=i, j=1,2,…,5; S in The negative electrode and S ip The positive electrodes are connected through a flying capacitor.

Images