Voltage control method and system for semi-centralized open-winding permanent magnet synchronous motor system

Abstract

The application provides a voltage control method and system of a semi-centralized open-winding permanent magnet synchronous motor system, and relates to the field of motor driving and control. The voltage control method of the semi-centralized open-winding permanent magnet synchronous motor system comprises sampling a direct current bus voltage, three-phase currents of a permanent magnet synchronous motor, a rotor position angle and a mechanical rotating angular velocity, and obtaining the three-phase currents of the permanent magnet synchronous motor in a dq0 coordinate system through coordinate transformation; the three-phase currents of the permanent magnet synchronous motor in the dq0 coordinate system at k moment are combined with the permanent magnet synchronous motor voltage in the dq0 coordinate system at k moment to predict the permanent magnet synchronous motor current at k+1 moment; wherein k moment represents any moment, and k+1 moment represents the next moment of k moment; while the control effect is maintained, the execution time of the program is shortened, and a shorter control period can be adopted to improve performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of motor driving and control, in particular to a voltage control method and system for a semi-centralized open-winding permanent magnet synchronous motor system. BACKGROUND

[0002] In a driving system composed of N motors, a traditional open-winding permanent magnet synchronous motor will need 2N inverters, which will occupy a huge volume and increase the cost. The number of inverters needed can be reduced to N+1 by making one side of these motors share one multiplex inverter, but these inverters belong to the same control system, which will cause the number of voltage vectors to increase exponentially, which is not conducive to using traditional model predictive control. SUMMARY

[0003] (I) Technical problems solved

[0004] In view of the deficiencies of the prior art, the present application provides a voltage control method and system for a semi-centralized open-winding permanent magnet synchronous motor system, which solves the problem that a traditional open-winding permanent magnet synchronous motor will need 2N inverters, which will occupy a huge volume and increase the cost. The number of inverters needed can be reduced to N+1 by making one side of these motors share one multiplex inverter, but these inverters belong to the same control system, which will cause the number of voltage vectors to increase exponentially, which is not conducive to using traditional model predictive control.

[0005] (II) Technical solutions

[0006] To achieve the above purpose, the present application is implemented by the following technical solutions:

[0007] On the one hand, a voltage control method for a semi-centralized open-winding permanent magnet synchronous motor system is provided, which comprises:

[0008] The DC bus voltage, the three-phase current of the permanent magnet synchronous motor, the rotor position angle and the mechanical rotational angular velocity are sampled, and the three-phase current of the permanent magnet synchronous motor in the dq0 coordinate system is obtained through coordinate transformation;

[0009] The permanent magnet synchronous motor current at k+1 time is predicted according to the three-phase current of the permanent magnet synchronous motor in the dq0 coordinate system at k time and the permanent magnet synchronous motor voltage in the dq0 coordinate system at k time; wherein k time represents any time, and k+1 time represents the next moment of k time;

[0010] The permanent magnet synchronous motor k+2 time cross-axis current reference value is obtained through the speed regulator, and the direct-axis current reference value and the zero-sequence current reference value are both set to 0, wherein k+2 time represents the next moment of k+1 time;

[0011] According to the permanent magnet synchronous motor phase current reference value at k+2 time and the permanent magnet synchronous motor phase current value at k+1 time, the voltage reference value of the permanent magnet synchronous motor at k+1 time in the synchronous rotating dq0 coordinate system is derived;

[0012] The voltage reference value of the permanent magnet synchronous motor is transformed into the phase voltage reference value in the abc coordinate system through coordinate transformation;

[0013] Each bridge arm and each winding of any phase is regarded as a control unit of the phase, and the phase voltage of any permanent magnet synchronous motor winding of the phase control unit is calculated;

[0014] The phase voltage deviation of any permanent magnet synchronous motor winding of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is low is calculated, and the phase voltage deviations of all permanent magnet synchronous motor windings of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is low are summed to obtain a total deviation;

[0015] The phase voltage deviation of any permanent magnet synchronous motor winding of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is high is calculated, and the phase voltage deviations of all permanent magnet synchronous motor windings of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is high are summed to obtain a total deviation;

[0016] The total deviations of all permanent magnet synchronous motor windings of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is high and low, respectively, are compared to obtain a multiplexing flag, and the state of the multiplexing inverter bridge arm of the phase control unit is determined;

[0017] The total flag of any permanent magnet synchronous motor winding of the phase control unit is calculated, and the state of the independent inverter bridge arm of the phase control unit is determined;

[0018] After comparing the results of the state of the multiplexing inverter bridge arm of the phase control unit and the state of the independent inverter bridge arm of the phase control unit, the states of all inverter bridge arms are determined, and then the driving signal is generated to control the switching state of the inverter bridge arm, thereby controlling the terminal voltage of the permanent magnet synchronous motor.

[0019] Preferably, the direct current bus voltage, the three-phase current of the permanent magnet synchronous motor, the rotor position angle, and the mechanical rotation angular velocity are sampled, and the three-phase current of the permanent magnet synchronous motor in the dq0 coordinate system is obtained through coordinate transformation, which is realized by the following formula:

[0020]

[0021] wherein, P n is the number of pole pairs, k represents the value at the current time, k+1 represents the value at the next time, and so on; the subscript n represents the value of the n motor, n=1, 2…N; ud表示 DC bus voltage c i a_n (k), i b_n (k), i c_n (k) represents the three-phase current of N permanent magnet synchronous motors, θ m_n (k) represents the rotor position angle, ω m_n (k) represents the mechanical rotational angular velocity.

[0022] Preferably, the step of predicting the permanent magnet synchronous motor current at time k+1 based on the three-phase current of the permanent magnet synchronous motor in the dq0 coordinate system at time k and the voltage of the permanent magnet synchronous motor in the dq0 coordinate system at time k; where time k represents any time and time k+1 represents the next time after time k, is achieved through the following formula:

[0023]

[0024] Among them, F n (k), G, H n (k) is a matrix;

[0025]

[0026]

[0027]

[0028] Among them, T s R is the sampling period; R is the phase resistance; L is the sampling period. d It is a direct-axis inductor; L q L0 is the quadrature-axis inductance; L0 is the zero-sequence inductance; ψ f1 ψ is the fundamental component of the magnetic flux linkage of the permanent magnet; f3 i represents the third harmonic component of the permanent magnet flux linkage; d_n (k), i q_n (k), i 0_n (k) represents the permanent magnet synchronous motor current at time k in the synchronously rotating dq0 coordinate system; u d_n (k), u q_n (k), u 0_n (k) represents the voltage of the permanent magnet synchronous motor in the synchronously rotating dq0 coordinate system at time k; i d_n (k+1),i q_n (k+1),i 0_n (k+1) represents the permanent magnet synchronous motor current at time k+1.

[0029] Preferably, the permanent magnet synchronous motor phase current reference value at k+2 time and the permanent magnet synchronous motor phase current value at k+1 time are used to derive the voltage reference value of the permanent magnet synchronous motor at k+1 time in the synchronous rotating dq0 coordinate system, which is realized by the following formula:

[0030]

[0031] wherein G -1 is the inverse matrix of G matrix; represents the k+2 time q-axis current reference value of N permanent magnet motors, represents the d-axis current reference value, represents the zero sequence current reference value, represents the k+1 time voltage reference value of the motor in the synchronous rotating dq0 coordinate system.

[0032] Preferably, the permanent magnet synchronous motor voltage reference value is converted into the phase voltage reference value in the abc coordinate system by coordinate transformation, which is realized by the following formula:

[0033]

[0034] wherein, represents the phase voltage reference value in the abc coordinate system obtained by coordinate transformation.

[0035] Preferably, each bridge arm and each winding of any phase is regarded as a control unit of the phase, and the phase voltage of any permanent magnet synchronous motor winding of the phase control unit is calculated by the following formula:

[0036] u m_n (k+1)=(S m_n -S m_(N+1) )*u dc

[0037] wherein S m_n is the state of any phase bridge arm of VS I-n, m=a, b, c, n=1, 2…N+1; S m_n =1 means that the bridge arm is high level and the terminal voltage is +u dc ; S m_n =0 means that the bridge arm is low level and the terminal voltage is 0.

[0038] Preferably, the phase voltage deviation of any permanent magnet synchronous motor winding of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is low is calculated, which specifically includes:

[0039] When the phase voltage reference value is located in the interval 1: (-u dc / 2, u dc / 2), flagm_n = 0, the optimal level is 0, and the m-phase bridge arm state S m_n = 0 of the independent inverter VSI-n can achieve the optimal level, the n-th motor winding phase voltage deviation of the m-phase control unit is

[0040]

[0041] When the phase voltage reference value is located in interval 2: [u dc / 2, ∞), flag m_n = 1, the optimal level is +u dc , and the m-phase bridge arm state S m_n = 1 of the independent inverter VSI-n can achieve the optimal level, the n-th motor winding phase voltage deviation of the m-phase control unit is

[0042]

[0043] When the phase voltage reference value is located in interval 3: (-∞, -u dc / 2), flag m_n = -1, the optimal level is -u dc , but it cannot be achieved due to S m_(N+1) = 0; the suboptimal level is 0, and the m-phase bridge arm state S m_n = 0 of the independent inverter VSI-n can achieve the suboptimal level, the n-th motor winding phase voltage deviation of the m-phase control unit is

[0044] The phase voltage deviations of all motor windings of the m-phase control unit when the multiplexing inverter VSI-(N+1) bridge arm of the m-phase control unit is low are summed to obtain a total deviation

[0045]

[0046] The phase voltage deviations of all permanent magnet synchronous motor windings of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is low are summed to obtain a total deviation, specifically:

[0047]

[0048] Wherein,

[0049] represents the phase voltage deviation of all permanent magnet synchronous motor windings of the m-phase control unit when the multiplexing inverter bridge arm of the m-phase control unit is low, which is summed to obtain a total deviation. ​​​

[0050] The phase voltage deviation of any permanent magnet synchronous motor winding of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is high, specifically comprising:

[0051] When the phase voltage reference value is located in interval 1:(-u dc / 2,u dc / 2), flag m_n =0, the optimal level is 0, and when the m-phase bridge arm state S m_n of the independent inverter VSI-n is 1, the optimal level can be achieved, and the phase voltage deviation of the n-th motor winding of the m-phase control unit is :

[0052]

[0053] When the phase voltage reference value is located in interval 2:[u dc / 2,∞), flag m_n =1, the optimal level is +u dc , but it cannot be achieved due to S m_(N+1) =1; the suboptimal level is 0, and when the m-phase bridge arm state S m_n of the independent inverter VSI-n is 1, the suboptimal level can be achieved, and the phase voltage deviation of the n-th motor winding of the m-phase control unit is :

[0054]

[0055] When the phase voltage reference value is located in interval 3:(-∞,-u dc / 2), flag m_n =-1, the optimal level is -u dc , and when the m-phase bridge arm state S m_n of the independent inverter VSI-n is 0, the optimal level can be achieved, and the phase voltage deviation of the n-th motor winding of the m-phase control unit is :

[0056]

[0057] The phase voltage deviations of all permanent magnet synchronous motor windings of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is high are summed to obtain a total deviation, specifically:

[0058]

[0059] wherein, The total deviation of the phase voltage of all the permanent magnet synchronous motor windings of the m-phase control unit is summed up when the multiplexing inverter bridge arm of the phase control unit is high to obtain a total deviation.

[0060] Preferably, the total flag of any permanent magnet synchronous motor winding of the phase control unit is calculated, and the bridge arm state of the independent inverter of the phase control unit is determined, specifically

[0061] Tf m_n = flag m_n + flag m_C

[0062] wherein Tf m_n represents the total flag of the n-th motor winding of the m-phase control unit, flag m_C represents the multiplexing flag.

[0063] In a second aspect, a voltage control system of a semi-centralized open-winding permanent magnet synchronous motor system is provided, which comprises at least one three-phase open-winding permanent magnet synchronous motor, at least one two-level independent voltage source type inverter, one two-level multiplexing voltage source type inverter, one speed closed loop unit, at least one predictive voltage control unit, and three bridge arm state confirmation units. The at least two inverters are connected in a common DC bus connection mode, and the at least one three-phase open-winding permanent magnet synchronous motor is powered from both ends at the same time. The at least one three-phase open-winding permanent magnet synchronous motor is referred to as No. 1 motor, No. 2 motor, …, and No. N motor, wherein N is a natural number. The positive terminal of the at least one three-phase open-winding permanent magnet synchronous motor uses one independent inverter, and the negative terminal of the at least one three-phase open-winding permanent magnet synchronous motor shares one multiplexing inverter. The independent inverter of each three-phase open-winding permanent magnet synchronous motor is referred to as VSI-1, VSI-2, …, and VSI-N, and the shared multiplexing inverter is referred to as VSI-N+1.

[0064] (Three) beneficial effects

[0065] This invention discloses a voltage control method and system for a semi-centralized open-winding permanent magnet synchronous motor system. By pre-setting the bridge arm states of the multiplexed inverter and introducing the concepts of optimal and suboptimal voltage levels, the state of all bridge arms can be quickly determined. In the process of confirming the bridge arm states of the m-phase control unit, only 5N adders, 2N multipliers, N+1 comparators, and N lookup table operations are required. The computational load increases linearly with N, avoiding the situation where the controller cannot execute due to an exponential explosion in computational load, and exhibiting good control performance. It solves the problem that traditional open-winding permanent magnet synchronous motors require 2N inverters, which would occupy a huge volume and increase costs. By having one multiplexed inverter share one side of these motors, the number of inverters required can be reduced to N+1. However, since these inverters belong to the same control system, the number of voltage vectors will increase exponentially, which is not conducive to the use of traditional model predictive control. Attached Figure Description

[0066] Figure 1 This is a flowchart of the control method of the present invention;

[0067] Figure 2 This is a block diagram of the voltage control system of the semi-centralized open-winding permanent magnet synchronous motor system of the present invention;

[0068] Figure 3 This is the topology of a semi-centralized open-winding permanent magnet synchronous motor in an embodiment of the present invention;

[0069] Figure 4 The above is an experimental waveform diagram of a simplified predictive voltage control strategy in an embodiment of the present invention. Detailed Implementation

[0070] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0071] Example

[0072] like Figure 1 As shown, this embodiment of the invention provides a voltage control method for a semi-centralized open-winding permanent magnet synchronous motor system, the method comprising:

[0073] (1) First, the DC bus voltage u dc The three-phase current i of N permanent magnet synchronous motors a_n (k), i b_n (k), i c_n (k), rotor position angle θ m_n (k), Mechanical rotational angular velocity ωm_n (k) is sampled, and i in the dq0 coordinate system is obtained through coordinate transformation. d_n (k), i q_n (k), i 0_n (k);

[0074]

[0075] Among them, P n Here, k represents the value at the current moment, k+1 represents the value at the next moment, and so on; the subscript n indicates the value of the nth permanent magnet synchronous motor (n=1,2…N);

[0076] (2) Based on the current i of the permanent magnet synchronous motor in the synchronously rotating dq0 coordinate system at the current time, i.e., time k. d_n (k), i q_n (k), i 0_n (k), combined with the current permanent magnet synchronous motor voltage value u in the dq0 coordinate system. d_n (k), u q_n (k), u 0_n Substituting (k) into the discrete-domain mathematical model, we can predict the permanent magnet synchronous motor current i at time k+1. d_n (k+1),i q_n (k+1),i 0_n (k+1);

[0077]

[0078] Among them, F n (k), G, H n (k) is a matrix;

[0079]

[0080]

[0081]

[0082] Among them, T s R is the sampling period; R is the phase resistance; L is the sampling period. d It is a direct-axis inductor; L q L0 is the quadrature-axis inductance; L0 is the zero-sequence inductance; ψ f1 ψ is the fundamental component of the magnetic flux linkage of the permanent magnet; f3 The third harmonic component of the permanent magnet flux linkage;

[0083] (3) Obtain the reference values ​​of the quadrature-axis current of the N permanent magnet synchronous motors at time k+2 through the speed regulator. and the direct-axis current reference value and zero-sequence current reference value are all set to 0;

[0084] (4) According to the principle of no error, the voltage reference value of the permanent magnet synchronous motor at k+1 time in the synchronous rotating dq0 coordinate system is derived from the phase current reference value of the permanent magnet synchronous motor at k+2 time and the phase current value i d_n (k+1) of the permanent magnet synchronous motor at k+1 time q_n (k+1) respectively 0_n

[0085]

[0086] wherein G -1 is the inverse matrix of G matrix;

[0087] (5) The voltage reference value of the permanent magnet synchronous motor is obtained by coordinate transformation to get the phase voltage reference value in abc coordinate system

[0088]

[0089] Steps (1)-(5) regard the n number of permanent magnet synchronous motor as an independent unit to predict the phase voltage reference value, and the process should be carried out once on the n number of permanent magnet synchronous motor (n=1, 2…N) respectively;

[0090] (6) The system regards each bridge arm and each winding of m phase as m phase control unit (m=a, b, c); according to table 1, the n number of permanent magnet synchronous motor phase voltage reference value of m phase control unit is classified, and its independent flag flag m_n is obtained, and the corresponding optimal level, suboptimal level is also shown in table 1:

[0091] Table 1

[0092]

[0093] S m_n is the m phase bridge arm state of VSI-n (m=a, b, c, n=1, 2…N+1), S m_n =1 means that the bridge arm is high level, and the terminal voltage is +u dc , S m_n =0 means that the bridge arm is low level, and the terminal voltage is 0. The execution phase voltage of the n number of permanent magnet synchronous motor winding of m phase control unit is determined by S m_n and S m_(N+1) :

[0094] u m_n (k+1) = (S m_n -S​m_(N+1) )*u dc

[0095] (7) Based on the situation in each interval, calculate the nth permanent magnet synchronous motor winding of the m-phase control unit when the VSI-(N+1) bridge arm of the multiplexed inverter of the m-phase control unit is at a low level (i.e., S m_(N+1) Phase voltage deviation (=0):

[0096] ① When the phase voltage reference value Located in interval 1:(-u dc / 2,u dc / 2) flag m_n =0, the optimal level is 0, when the m-phase bridge arm state S of the independent inverter VSI-n is 0. m_n The optimal level can be achieved when the value is 0, which is the phase voltage deviation of the nth permanent magnet synchronous motor winding in the m-phase control unit. for:

[0097]

[0098] ②When the phase voltage reference value Located in interval 2: [u dc When / 2,∞), flag m_n =1, the optimal level is +u dc When the m-phase bridge arm state S of the independent inverter VSI-n m_n The optimal level can be achieved when = 1, and the phase voltage deviation of the nth permanent magnet synchronous motor winding in the m-phase control unit is... for:

[0099]

[0100] ③ When the phase voltage reference value Located in interval 3:(-∞,-u dc / 2) flag m_n =-1, the optimal level is -u dc However, due to S m_(N+1) =0 and cannot be achieved; the suboptimal level is 0, when the m-phase bridge arm state S of the independent inverter VSI-n is 0. m_n When the voltage is 0, a suboptimal level can be achieved. The phase voltage deviation of the nth permanent magnet synchronous motor winding in the m-phase control unit is... for:

[0101]

[0102] (8) The total deviation is obtained by summing the phase voltage deviations of all permanent magnet synchronous motor windings in the m-phase control unit when the VSI-(N+1) bridge arm of the multiplexed inverter in the m-phase control unit is at a low level.

[0103]

[0104] (9) Based on the situation in each interval, calculate the nth permanent magnet synchronous motor winding of the m-phase control unit when the VSI-(N+1) bridge arm of the multiplexed inverter of the m-phase control unit is at a high level (i.e., S m_(N+1) =1) Phase voltage deviation:

[0105] ① When the phase voltage reference value Located in interval 1:(-u dc / 2,u dc / 2) flag m_n =0, the optimal level is 0, when the m-phase bridge arm state S of the independent inverter VSI-n is 0. m_n The optimal level can be achieved when = 1, and the phase voltage deviation of the nth permanent magnet synchronous motor winding in the m-phase control unit is... for:

[0106]

[0107] ②When the phase voltage reference value Located in interval 2: [u dc When / 2,∞), flag m_n =1, the optimal level is +u dc However, due to S m_(N+1) =1 and cannot be achieved; the suboptimal level is 0, when the m-phase bridge arm state S of the independent inverter VS In is... m_n When = 1, a suboptimal level can be achieved, and the phase voltage deviation of the nth permanent magnet synchronous motor winding in the m-phase control unit is... for

[0108]

[0109] ③ When the phase voltage reference value Located in interval 3:(-∞,-u dc / 2) flag m_n =-1, the optimal level is -u dc When the m-phase bridge arm state S of the independent inverter VSI-n m_n The optimal level can be achieved when the value is 0, which is the phase voltage deviation of the nth permanent magnet synchronous motor winding in the m-phase control unit. for:

[0110]

[0111] (10) The total deviation is obtained by summing the phase voltage deviations of all permanent magnet synchronous motor windings in the m-phase control unit when the multiplexed inverter VS I-(N+1) bridge arm of the m-phase control unit is at a high level.

[0112]

[0113] (11) comparing total deviations of all permanent magnet synchronous motor windings of the m-phase control unit when the multiplexed inverter VSI-(N+1) bridge arm of the m-phase control unit is respectively high and low, obtaining a multiplexing flag flag according to Table 2, and determining the state of the multiplexed inverter VSI-(N+1) bridge arm of the m-phase control unit: m_C

[0114] Table 2

[0115]

[0116] (12) calculating the total flag Tf of the n-th permanent magnet synchronous motor winding of the m-phase control unit m_n , and determining the state of the independent inverter VSI-n bridge arm of the m-phase control unit according to Table 3:

[0117] Tf m_n =flag m_n +flag m_C

[0118] Table 3

[0119]

[0120] Steps (6)-(11) regard the m-phase control unit as an independent unit to determine the state of each bridge arm of the m-phase control unit, and the process should be performed once on a, b and c three phases respectively;

[0121] (13) after determining the state of all inverter bridge arms according to the comparison results of (11)-(12), generating a driving signal to control the switching state of the inverter bridge arm, and further controlling the terminal voltage of the permanent magnet synchronous motor. At the same time, the running state of the permanent magnet synchronous motor at the k+1 moment is sampled, and the next control cycle is entered.

[0122] In order to verify the effect of the application, an experiment is carried out. Figure 3 is a semi-centralized open-winding permanent magnet synchronous motor topology, Figure 2 is a control block diagram of a simplified predictive voltage control system of a semi-centralized open-winding permanent magnet synchronous motor system, Figure 4 is an experimental waveform adopting a simplified predictive voltage control strategy. Figure 4 The experimental results of the application show that the simplified predictive voltage control system based on the semi-centralized open-winding permanent magnet synchronous motor can stably and cooperatively control at least four permanent magnet synchronous motors and effectively suppress the zero sequence current within ±0.3A, and can be theoretically used for any number of semi-centralized open-winding permanent magnet synchronous motor systems.

[0123] ​The application further provides a voltage control system of a semi-centralized open-winding permanent magnet synchronous motor system, which comprises at least one three-phase open-winding permanent magnet synchronous motor, at least one two-level independent voltage source type inverter, one two-level multiplex voltage source type inverter, one speed closed loop unit, at least one predictive voltage control unit and three bridge arm state confirmation units, at least two inverters are connected in a common DC bus mode, at least one three-phase open-winding permanent magnet synchronous motor is powered from both ends at the same time, the at least one three-phase open-winding permanent magnet synchronous motor is referred to as No. 1 motor, No. 2 motor, …, No. N motor, wherein N is a natural number, the positive terminal of the at least one three-phase open-winding permanent magnet synchronous motor uses one independent inverter, the negative terminal of the at least one three-phase open-winding permanent magnet synchronous motor shares one multiplex inverter, the independent inverters of each three-phase open-winding permanent magnet synchronous motor are referred to as VS I-1, VS I-2, …, VS I-N, and the shared multiplex inverter is referred to as VS I-N+1. The a-phase voltage of No. n motor (n = 1, 2, …, N) can be controlled by controlling the a-phase bridge arm of VS I-n and VS I-N+1, and the b-phase and c-phase are the same; the predictive voltage control unit-n samples the DC bus voltage data of the phase current, rotor speed, rotor position and inverter of No. n motor, respectively calculates the reference phase voltage of each phase at the next moment, and then the bridge arm state confirmation unit confirms the optimal state of the independent bridge arm and the multiplex bridge arm in turn to generate a control signal to be sent into the inverter to control the bridge arm switch state of the inverter, thereby forming a closed loop control system of inverter-motor-control unit-inverter.

[0124] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... " does not, without more limitations, preclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element.

Claims

1. A voltage control method of a semi-centralized open-winding permanent magnet synchronous motor system, characterized by, The method comprises the following steps: sampling the direct current bus voltage, the three-phase current of the permanent magnet synchronous motor, the rotor position angle and the mechanical rotation angular velocity, and obtaining the three-phase current of the permanent magnet synchronous motor in the dq0 coordinate system through coordinate transformation; deriving the permanent magnet synchronous motor current at k+1 time according to the three-phase current of the permanent magnet synchronous motor in the dq0 coordinate system at k time and the permanent magnet synchronous motor voltage in the dq0 coordinate system at k time; wherein k time represents any time, and k+1 time represents the next moment of k time; obtaining the permanent magnet synchronous motor k+2 time cross-axis current reference value through the speed regulator, and setting the direct-axis current reference value and the zero sequence current reference value to 0; wherein k+2 time represents the next moment of k+1 time; deriving the permanent magnet synchronous motor voltage reference value in the synchronous rotating dq0 coordinate system at k+1 time according to the permanent magnet synchronous motor phase current reference value at k+2 time and the permanent magnet synchronous motor phase current value at k+1 time; obtaining the phase voltage reference value in the abc coordinate system through coordinate transformation of the permanent magnet synchronous motor voltage reference value; regarding each bridge arm and each winding of any phase as a control unit of the phase, and calculating the phase voltage executed by any permanent magnet synchronous motor winding of the phase control unit; calculating the phase voltage deviation of any permanent magnet synchronous motor winding of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is low; summing the phase voltage deviations of all permanent magnet synchronous motor windings of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is low to obtain the total deviation; calculating the phase voltage deviation of any permanent magnet synchronous motor winding of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is high; summing the phase voltage deviations of all permanent magnet synchronous motor windings of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is high to obtain the total deviation; comparing the total deviations of all permanent magnet synchronous motor windings of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is high and low respectively to obtain the multiplexing flag bit, and determining the multiplexing inverter bridge arm state of the phase control unit; calculating the total flag bit of any permanent magnet synchronous motor winding of the phase control unit, and determining the bridge arm state of the independent inverter of the phase control unit; comparing the results of the multiplexing inverter bridge arm state of the phase control unit and the bridge arm state of the independent inverter of the phase control unit, determining all inverter bridge arm states, generating a driving signal to control the switching state of the inverter bridge arm, and further controlling the terminal voltage of the permanent magnet synchronous motor; the calculation of the phase voltage deviation of any permanent magnet synchronous motor winding of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is low specifically comprises: When the phase voltage reference value is located in the interval 1:(-u dc / 2,u dc / 2), u dc represents the DC bus voltage, the independent flag bit flag m_n =0, and the optimal level is 0, which is realized when the m-phase bridge arm state S m_n of the independent inverter VSI-n =0, and the n-number motor winding phase voltage deviation of the m-phase control unit is : When the phase voltage reference value (k+1) is in the interval 2: [u dc / 2,∞), the independent flag bit flag m_n =1, and the optimal level is +u dc When the m-phase bridge arm state S m_n of the independent inverter VSI-n is 1, the optimal level is realized, and the n-number motor winding phase voltage deviation of the m-phase control unit is : When the phase voltage reference value is located in interval 3: (-∞, -u dc / 2), the independent flag bit flag m_n = -1, the optimal level is -u dc , but it cannot be realized because S m_(N+1) = 0; the suboptimal level is 0, which is realized when the m-phase bridge arm state S m_n = 0 of the independent inverter VSI-n, and the n-number motor winding phase voltage deviation of the m-phase control unit is : the summing of the phase voltage deviations of all permanent magnet synchronous motor windings of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is low to obtain the total deviation specifically comprises: wherein, represents the total deviation obtained by summing up the phase voltage deviations of all the permanent magnet synchronous motor windings of the m-phase control unit when the multiplexed inverter bridge arm of the m-phase control unit is at low level; the calculation of the phase voltage deviation of any permanent magnet synchronous motor winding of the phase control unit when the multiplexing inverter bridge arm of the phase control unit is high specifically comprises: When the phase voltage reference value is located in the interval 1: (-u dc / 2, u dc / 2), the independent flag bit flag m_n = 0, and the optimal level is 0, which is realized when the m-phase bridge arm state S m_n of the independent inverter VSI-n = 1, and the n-number motor winding phase voltage deviation of the m-phase control unit is: When the phase voltage reference value is located in the interval 2: [u dc / 2, ∞), the independent flag bit flag m_n = 1, and the optimal level is +u dc , but it cannot be realized because S m_(N+1) = 1; the suboptimal level is 0, which is realized when the m-phase bridge arm state S m_n = 1 of the independent inverter VSI-n, and the n-number motor winding phase voltage deviation of the m-phase control unit is: ​ When the phase voltage reference value is located in interval 3: (-∞, -u dc / 2), the independent flag bit flag m_n = -1, and the optimal level is -u dc When the m-phase bridge arm state S m_n of the independent inverter VSI-n is 0, the optimal level is realized, and the n-number motor winding phase voltage deviation of the m-phase control unit is: ​ The phase voltage deviation of all permanent magnet synchronous motor windings of the phase control unit is summed up to obtain a total deviation when the multiplexing inverter bridge arm of the phase control unit is high, specifically: wherein, represents the total deviation of the phase voltage of all permanent magnet synchronous machine windings of the m-phase control unit when the multiplexed inverter bridge arms of the m-phase control unit are high.

2. The voltage control method of a semi-centralized open-winding permanent magnet synchronous motor system according to claim 1, characterized in that: The DC bus voltage, the three-phase current of the permanent magnet synchronous motor, the rotor position angle, and the mechanical rotation angular velocity are sampled, and the three-phase current of the permanent magnet synchronous motor in the dq0 coordinate system is obtained through coordinate transformation, which is realized through the following formula: wherein, i d_n (k), i q_n (k), i 0_n (k) represents the current of the permanent magnet synchronous motor in the synchronous rotating dq0 coordinate system at time k; P n is the number of pole pairs, k represents the value at the current time, k+1 represents the value at the next time, and so on; the subscript n represents the value of the n motor, n = 1, 2, …, N; i a_n (k), i b_n (k), i c_n (k) represents the three-phase current of the N permanent magnet synchronous motors, θ m_n (k) represents the rotor position angle.

3. The voltage control method of a semi-centralized open-winding permanent magnet synchronous motor system according to claim 2, characterized in that: The three-phase current of the permanent magnet synchronous motor in the dq0 coordinate system at k time is combined with the permanent magnet synchronous motor voltage in the dq0 coordinate system at k time to derive the permanent magnet synchronous motor current at k+1 time, which is realized through the following formula: wherein F n (k), G, H n (k) is a matrix; where T s is the sampling period; R is the phase resistance; L d is the direct-axis inductance; L q is the quadrature-axis inductance; L0 is the zero-sequence inductance; ψ f1 is the fundamental component of the permanent magnet flux linkage; ψ f3 is the third harmonic component of the permanent magnet flux linkage; u d_n (k), u q_n (k), u 0_n (k) represents the voltage of the permanent magnet synchronous motor at time k in the synchronous rotating dq0 coordinate system; i d_n (k+1), i q_n (k+1), i 0_n (k+1) represents the current of the permanent magnet synchronous motor at time k+1; ω m_n (k) represents the mechanical rotating angular velocity.

4. The voltage control method of a semi-centralized open-winding permanent magnet synchronous motor system according to claim 3, characterized in that: The permanent magnet synchronous motor phase current reference value at k+2 time and the permanent magnet synchronous motor phase current value at k+1 time are used to derive the voltage reference value of the permanent magnet synchronous motor in the synchronous rotating dq0 coordinate system at k+1 time, which is realized through the following formula: where G is the inverse matrix of G matrix; -1 where G is the inverse matrix of G matrix; represents the k+2 time axis current reference value of N permanent magnet motor, represents the direct axis current reference value, represents the zero sequence current reference value, represents the k+1 time axis voltage reference value of the motor in the synchronous rotating dq0 coordinate system.

5. The voltage control method of a semi-centralized open-winding permanent magnet synchronous motor system according to claim 4, characterized in that: The permanent magnet synchronous motor voltage reference value is transformed into the phase voltage reference value in the abc coordinate system through coordinate transformation, which is realized through the following formula: wherein, represents the phase voltage reference value in the abc coordinate system obtained by coordinate transformation.

6. The voltage control method of a semi-centralized open-winding permanent magnet synchronous motor system according to claim 5, characterized in that: Each bridge arm and each winding of any phase is regarded as the control unit of the phase, and the phase voltage of any permanent magnet synchronous motor winding of the phase control unit is calculated, which is realized through the following formula: u m_n (k+1) = (S m_n -S m_(N+1) )*u dc wherein S m_n is any phase leg state of VSI-n, m = a, b, c, n = 1, 2,... N+1; S m_n = 1 means that the leg is high, the terminal voltage is +u dc ; S m_n = 0 means that the leg is low, the terminal voltage is 0.

7. The voltage control method of a semi-centralized open-winding permanent magnet synchronous motor system according to claim 6, characterized in that: The total flag bit of any permanent magnet synchronous motor winding of the phase control unit is calculated, and the bridge arm state of the independent inverter of the phase control unit is determined, specifically: Tf m_n = flag m_n + flag m_C wherein Tf m_n represents the total flag bit of the m-phase control unit, flag m_C represents the multiplexing flag bit.

8. A voltage control system for a semi-centralized open-winding permanent magnet synchronous motor system for performing the method of any one of claims 1-7, characterized in that, The application comprises at least one three-phase open-winding permanent magnet synchronous motor, at least one two-level independent voltage source type inverter, one two-level multiplex voltage source type inverter, one speed closed loop unit, at least one predictive voltage control unit, and three bridge arm state confirmation units. At least two inverters are connected in a common DC bus mode, and at least one three-phase open-winding permanent magnet synchronous motor is supplied from both ends at the same time. The at least one three-phase open-winding permanent magnet synchronous motor is referred to as No. 1 motor, No. 2 motor, …, and No. N motor, wherein N is a natural number. The positive terminal of the at least one three-phase open-winding permanent magnet synchronous motor uses one independent inverter, and the negative terminal of the at least one three-phase open-winding permanent magnet synchronous motor shares one multiplex inverter. Each independent inverter of the three-phase open-winding permanent magnet synchronous motor is referred to as VSI-1, VSI-2, …, and VSI-N, and the shared multiplex inverter is referred to as VSI-N+1.

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