CN111313767A - Orthogonal dual-motor current sensor cooperation system based on chopping period and correction method - Google Patents

Abstract

The invention provides a chopping period based orthogonal double-motor current sensor cooperative system, in a double-motor group control system, the input voltage of an inverter direct current bus of double motors is hung at the same input port, an inverter three-phase bridge arm of each motor subsystem is correspondingly connected with a motor three-phase winding, a cable of each motor three-phase winding respectively passes through a corresponding current sensor signal detection port in the forward direction, the time-sharing observation of the error of the current sensor of the double-motor system is realized, and finally the current sampling error cooperative correction between the multiple motor systems is realized by utilizing the observed value of the bus current. The invention can realize the cooperative correction of the sampling error of the current sensor among all motor systems, and has the advantages of simpler control algorithm, better applicability and higher error estimation time effectiveness.

Description

Orthogonal dual-motor current sensor cooperation system based on chopping period and correction method

Technical Field

The invention relates to the field of motor group control, in particular to a double-motor cooperative control method.

Background

The motor group control is an important development direction of future motor system control, and especially for some scenes needing multi-motor cooperative control, the motor group control is very important. One important direction of research in the control of motor groups is the current balancing control, or current sharing control. The most critical part for realizing the control requirements of the control method is current sampling, feedback and cooperative control. Therefore, the accuracy of the current feedback information directly affects or limits the effect of the cooperative control. Due to the principle and practical factors of the current sensor and the sampling circuit thereof, in actual use, current sampling errors are inevitably generated under the influence of factors such as operating conditions, environment, aging and the like. These current sampling errors can have a very adverse effect on the control of the motor group, especially in the aspect of current cooperative control. In addition, in a more serious case, the errors of the current sampling loops in each single motor system are different, and the errors of the current sampling loops in different motor systems are different. Therefore, a great challenge to the control of the motor group, especially to the current distribution or cooperative control, is that various current sampling errors exist, the current sampling errors are wide in distribution and poor in correlation, and a plurality of scientific and technical problems such as time variation and nonlinearity exist. Therefore, the problem of correcting the current sampling error is particularly important for motor group control, especially motor cooperative control and current distribution control. At present, the correction method for the sampling error of the motor current is mainly based on complex control algorithms such as observer, digital filter, etc. (related algorithms are described in documents 1-3, wherein document 1 is HaoYan, Yongxiang Xu, Weiduo Zhao, He Zhang, christgerada, "DC driver transmitter for the same-phase current transmission with single-phase current transmitter," IEEE Transactions on Magnetics, vol.55, No.2, pp.8100604, feb.2019. (journal of trim, pen Wang, Yi Tang, Leong Hai Koh, Fook Hoong, "Compensation of DC offset, and DC sampling and correction of current sampling error," focus of DC offset, wo 14-12, wo 14, wo 12, k hoo, wo 12, k, c, k, DC offset, wo 14, wo 12, "IEEE Transactions on industrial Electronics, vol.66, No.9, pp.6727-6736, sep.,2019 (journal article) ], however, this kind of method has a technical problem that is difficult to overcome for the current sensor error correction problem in the application of motor group control. On one hand, the methods are provided for single-motor systems, which can realize error correction of each single-motor system, but cannot realize balance of current gain errors among multiple-motor systems, which is an indispensable key link for systems requiring current distribution or cooperative control. On the other hand, the methods usually need to utilize a large number of complex calculation methods to realize the correction process, which undoubtedly increases more calculation amount for the originally very complex motor group control algorithm, and the applicability is not good. Therefore, it is necessary to research the current sensor error correction problem, especially the current sensor error system correction problem, for the application environment of the motor group system cooperative control, especially the multi-motor current distribution or cooperative control system.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a quadrature dual-motor current sensor cooperation system based on a chopping period and a correction method. In order to solve the problem that the influence caused by current sampling errors of a multi-motor current distribution or cooperative control system is difficult to eliminate, the method can not only realize the accurate correction of the current sampling errors of each single-motor system, but also realize the error cooperative correction among all sub-motor systems by taking the whole motor group system as a whole, finally ensure the accurate control of the motor group system control, and has the advantages of small required calculation amount and simple implementation method.

The technical scheme adopted by the invention for solving the technical problems is as follows:

in a double-motor group control system, inverter direct-current bus input voltages of double motors are attached to the same input port, inverter three-phase bridge arms of each motor subsystem are correspondingly connected with motor three-phase windings respectively, cables of the motor three-phase windings respectively penetrate through corresponding current sensor signal detection ports in the forward direction, time-sharing observation of errors of current sensors of the double motor systems is achieved by utilizing the relevance of the direct-current bus current sensors attached to the double motor systems and the three-phase currents of the double motors, current sampling errors of the single motor systems are estimated respectively, and finally current sampling errors among the multiple motor systems are corrected in a coordinated mode by utilizing observed values of the bus currents.

The invention also provides a correction method based on the chopping period orthogonal double-motor current sensor cooperation system, which comprises the following specific steps:

step 1: two motor driving groups in the double-motor group are respectively hung at the same direct-current bus end, and the detection value of the current sensor is represented by formulas (1) to (3):

wherein i_AM1、i_BM1、i_CM1And i_AM2、i_BM2、i_CM2A, B, C three-phase current detection values, k, respectively representing the first and second motors_A1、k_B1、k_C1And f_A1、f_B1、f_C1A, B, C three-phase current sensor gain error and offset error, k, respectively representing the motor set one_A2、k_B2、k_C2And f_A2、f_B2、f_C2A, B, C three-phase current sensor gain error and offset error, i, respectively representing the second motor group_PMIndicating the current detection value, k, of the DC bus current sensor_P、f_PRespectively representing the gain of the DC bus current sensorError and bias error;

in the formula (3), i_P1And i_P2Is shown in Table 1, wherein S₀₀₀～S₁₁₁Eight switching states, S, of the inverter 1₀₀₀'～S₁₁₁' denotes eight switching states of the inverter 2, where S₀₀₀～S₁₁₁And S₀₀₀'～S₁₁₁Subscript numbers "0" and "1" of' respectively indicate the switch states of three-phase bridge arms of the corresponding inverter A, B, C from left to right, a "0" indicates that a lower tube of the corresponding phase bridge arm is conducted and a lower tube of the corresponding phase bridge arm is not conducted, and a "1" indicates that the upper tube of the corresponding phase bridge arm is conducted and the lower tube is not conducted;

TABLE 1

On-off state

S000

S100

S110

S010

S011

S001

S101

S111

Vector of fundamental voltage

V0

V1

V2

V3

V4

V5

V6

V7

iP1

0

iA1

-iC1

iB1

-iA1

iC1

-iB1

0

On-off state

S000'

S100'

S110'

S010'

S011'

S001'

S101'

S111'

Vector of fundamental voltage

V0'

V1'

V2'

V3'

V4'

V5'

V6'

V7'

iP2

0

iA2

-iC2

iB2

-iA2

iC2

-iB2

0

The method comprises the steps of orthogonalizing inverter triangular carriers of two motor sets in a motor group, wherein chopping periods of the two inverters are T_sThe triangular carrier of the inverter 1 is increased forward to a half period value, i.e., T_sAt the time of/4, the triangular carrier of the inverter 2 starts to increase from 0 in the positive direction, and any one inverter chopping period is positioned at T_s/4 or 3T_sIn the case of/4, the chopping period of the other inverter must be at the beginning of the chopping period or T_sAt/2, the voltage vector of the other inverter is just V₀(V₀') or V₇(V₇') whose bus current value i is known from Table 1_P2(i_P1) Is also exactly 0, the conclusion obtained according to the formula (3) is that the direct current bus current value i_PIs exactly equal to the bus current value i of the first inverter_P1This relationship is shown in Table 2, where i_XAnd i_X' represents a certain basic voltage vector V in the inverter 1 and the inverter 2, respectively_XAnd V_X' such inversion under actionThe value of the direct current bus current;

TABLE 2

Inverter 1 triangular carrier time	0	Ts/4	Ts/2	3Ts/4
					Inverter 1 fundamental voltage vector	V0	VX	V7	VX
iP1	0	iX	0	iX
					Inverter 2 triangular carrier time	3Ts/4	0	Ts/4	Ts/2
Inverter 2 fundamental voltage vector	VX'	V0'	VX'	V7'
					iP2	iX'	0	iX'	0
iP	iX'	iX	iX'	iX

As can be seen from table 2, when the inverter 1 is at its triangular carrier T_s/4 or 3T_sAt/4, the input current value i at the main terminal of the direct current bus of the motor group_POnly with a certain phase current value i of the motor group I_XIn relation to when the inverter 2 is at its triangular carrier T_s/4 or 3T_sAt/4, the input current value i at the main terminal of the direct current bus of the motor group_PIs only related to a certain phase current value of the second motor set i_X'；

The sensor error correction strategy is as follows:

before correction, in each motor group in the motor group, three-phase feedback current values are obtained by detection of respective three-phase current sensors, and detection points of the three-phase feedback current values can be set according to actual requirements;

step 2: according to current sampling point t₁Respectively selecting 2 current sampling points which meet the conditions, namely t is met₁Time of day requested t_{1_1}、t_{1_2}Respectively sampling the values of the A-phase current sensor and the bus current sensor at two current sampling points to obtain corresponding current values, and obtaining two defined variables delta i by using a formula (5) as shown in a formula (4)_{AM1_t1}、Δi_{PM_t1}(ii) a The method comprises the following specific steps:

a. electric machine set 1

Defining 6 time variables, t₁、t₃、t₅、t₁'、t₃'、t₅' selecting method as shown in table 3, in order to make the basic voltage vector corresponding to each time meet the relationship of table 3, the times should be set at the positions where the output voltage vector is close to the relevant basic voltage vector;

TABLE 3

Selecting two satisfying t₁Time of day requested t_{1_1}、t_{1_2}Under the action of the two time points, the current sampling values of the first motor set and the bus current sensor are respectively expressed by a formula (4):

wherein i_{AM1_t1_1}、i_{AM1_t1_2}Respectively represent t_{1_1}、t_{1_2}Sampling value i of A-phase current sensor of the two-time motor set_{A1_t1_1}、i_{A1_t1_2}Respectively represent t_{1_1}、t_{1_2}True value, i, of phase A current of the two-time motor group_{PM_t1_1}、i_{PM_t1_2}Respectively represent t_{1_1}、t_{1_2}Sampling value i of bus current sensor of motor group at two moments_{P_t1_1}、i_{P_t1_2}Respectively represent t_{1_1}、t_{1_2}The real value of the bus current of the motor group at the two momentsThe actual value i of the A-phase current of the motor set at the two moments_{A1_t1_1}、i_{A1_t1_2}Equal;

t_{1_1}、t_{1_2}the selection principle of the two times is to make the difference between the corresponding current detection values larger, set a relevant threshold value to realize, and use each equation in the formula (4) to make difference to obtain a formula (5):

wherein Δ i_{AM1_t1}、Δi_{PM_t1}At t, the current sensor is respectively an A-phase current sensor of the motor set and a bus current sensor of the motor group_{1_1}、t_{1_2}The difference between the values detected at these two moments, the values of these two variables being available, Δ i_{A1_t1}The real value of the phase A current of the motor set is t_{1_1}、t_{1_2}The difference between these two times;

according to current sampling point t₃Respectively selecting 2 current sampling points which meet the conditions, namely t is met₃Time of day requested t_{3_1}、t_{3_2}Respectively sampling the values of the B-phase current sensor and the bus current sensor at two current sampling points to obtain corresponding current values, and obtaining two defined variables delta i by using a formula (6)_{BM1_t3}、Δi_{PM_t3}；

According to current sampling point t₅Respectively selecting 2 current sampling points which meet the conditions, namely t is met₅Time of day requested t_{5_1}、t_{5_2}. Respectively sampling the values of the C-phase current sensor and the bus current sensor at the two current sampling points to obtain corresponding current values, and obtaining two defined variables delta i by using a formula (7)_{CM1_t5}、Δi_{PM_t5}；

The method comprises the following specific steps:

by using a similar method, the current relationship between two phases of the motor group one B, C and the relevant time is obtained, as shown in formula (6) and formula (7), wherein the definition of the relevant variables is similar to that of the phase a:

by using the formulas (5) to (7), the gain error ratio relationship between the A, B, C three-phase current sensor of the first motor group and the bus current sensor of the motor group is obtained as shown in the formula (8):

in addition, with t₁Requiring similar choices of time t₄At that time, the action vector of the inverter 1 is V₄Under the action of the time point, the current values of the A-phase and bus current sensors of the motor set are sampled, the current sampling values are respectively expressed by a formula (9), wherein the definition of related variables and t₁Similarity of time of day;

obtaining delta i by using the relevant current sampling value and combining the formula (4) and the formula (9)_{AM1PM_t1_1}And Δ i_{AM1PM_t4}The values of two variables;

wherein Δ i_{AM1PM_t1_1}Is shown at t_{1_1}The difference value delta i of the measured current value of a current sensor of an A-phase of the motor group and a current sensor of a direct current bus of the motor group under the gain error proportionality coefficient at the moment_{AM1PM_t4}Is shown at t₄The method comprises the steps that a current sensor of a motor set A phase and a current sensor of a motor set DC bus measure the difference value of the current value under a gain error proportionality coefficient at any moment, and the two values can be obtained according to measured data;

obtaining an offset error between a motor set A-phase current sensor and a motor group direct current bus current sensor by using a formula (10), wherein the offset error is expressed by using a formula (11):

and t₃Time of day requirement selection t₆At that time, the action vector of the inverter 1 is V₆Sampling current values of a first phase B current sensor of the motor set and a bus current sensor, and obtaining a bias error of the first phase B current sensor of the motor set by applying an A phase processing method, as shown in a formula (12);

and t₅Time of day requirement selection t₂At that time, the action vector of the inverter 1 is V₂Sampling current values of a C-phase current sensor and a bus current sensor of the motor set, and obtaining a bias error of the C-phase current sensor of the motor set by applying an A-phase processing method, wherein the bias error is shown in a formula (12);

where the relevant variables and test methods are similar to those of phase a:

therefore, bias errors of all current sensors of a motor set and current sensors at the input end of a direct current bus of the motor group are eliminated, and gain errors are balanced;

b. motor set two

Similar to the method of the motor group, the bias errors of all the current sensors of the motor group and the current sensors at the input end of the direct current bus of the motor group are eliminated, and the gain errors are balanced, as shown in formula (13):

and step 3: motor group gain error cooperative correction

In two motor sets involved in motor group control, offset errors are corrected by respective systems, however, gain errors can only achieve balance in the sets, and the two motor sets need to be corrected by a system correction strategy, that is, by using the first terms of formula (8) and formula (13), the gain error ratios of 7 current sensors including 2 motor sets and a motor group direct current bus are obtained as shown in formula (14):

and (3) by using a formula (14), taking the bus current sensor as a reference, and proportionally and sequentially eliminating the gain error of each current sensor, wherein the elimination method is to proportionally divide the sampling current by a corresponding proportional coefficient.

The invention has the advantages that aiming at the problem of current sensor sampling error correction in the field of motor group system control, especially dual-motor current distribution or cooperative control, the invention has the following advantages:

(1) the invention can realize the cooperative correction of the sampling error of the current sensor among all motor systems: the invention fully utilizes the provided drive control method with mutually orthogonal chopping periods, realizes the current sampling error cooperative correction among multiple motor subsystems through the current value of a direct current bus side which is simultaneously hung by the double motor systems, and finally realizes the current distribution or cooperative control requirement of each motor subsystem in the motor group control;

(2) the control algorithm required by the invention is simpler and has better applicability: the current sensor error collaborative correction scheme of the motor group provided by the invention does not need complex observers, digital filters and other algorithms, so that the calculated amount can be ignored and the applicability is better compared with the prior art;

(3) the invention has higher validity of error estimation time: the means for realizing the correction scheme in the prior art is mainly realized by using a complex algorithm such as an observer and the like, is limited to principle requirements, and needs to contain the whole control system in a control strategy of the control system, so that the error estimation time is limited by various influences such as observer delay, system response delay and the like, the estimation time is often long and may be influenced by operation conditions.

Drawings

FIG. 1 is a schematic diagram of a two-motor cluster current sensor error co-correction system of the present invention.

FIG. 2 is a schematic diagram of the chopper period quadrature-based correction for a first motor group according to the present invention.

FIG. 3 is a schematic diagram of the chopper period quadrature-based correction for motor set two according to the present invention.

In the figure V_DCIs DC bus voltage of motor driving system, P and N represent the input positive and negative terminals of DC bus voltage, i_PIs the forward current of the P end of the DC bus i_P1、i_P2Input forward currents i of the inverter 1 and the inverter 2, respectively_A1、i_B1、i_C1A, B, C three-phase real current values i of the motor set I_A2、i_B2、i_C2A, B, C three-phase real current value, T, of the second motor group_sIs the switching period of the inverter, V₀～V₇Is 8 basic voltage vectors, V, in the inverter 1_XAnd V_X' represents one of the inverter 1 and the inverter 2, respectivelyA basic voltage vector, V₀'～V₇' is 8 basic voltage vectors in the inverter 2, t₁、t₃、t₅、t₁'、t₃'、t₅' respectively indicates the time when a specific condition is satisfied, V_out1、V_out2Respectively, the inverter 1 and the inverter 2 output voltage vectors.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

A chopping period orthogonal double-motor current sensor cooperative system is characterized in that in a double-motor group control system, the input voltage of an inverter direct current bus of double motors is attached to the same input port, an inverter three-phase bridge arm of each motor subsystem is correspondingly connected with a motor three-phase winding, a cable of each motor three-phase winding respectively penetrates through a corresponding current sensor signal detection port in the forward direction, the time-sharing observation of the current sensor error of the double motor system is realized by utilizing the relevance of the direct current bus current sensor simultaneously attached to the double motor system and the three-phase current of the double motors, the method for realizing the orthogonal chopping periods is combined, the current sampling error of each single motor system is estimated respectively, and the current sampling error cooperative correction between the multiple motor systems is realized by utilizing the observed value of the bus current finally.

A correction method based on a chopping period orthogonal double-motor current sensor cooperation system comprises the following specific steps:

step 1: in fig. 1, two motor driving groups in a dual-motor group are respectively hung at the same dc bus end, and the detection values of the current sensors are expressed by formulas (1) to (3) in consideration of the measurement errors of the sensors and the signal conditioning circuits thereof:

wherein i_AM1、i_BM1、i_CM1And i_AM2、i_BM2、i_CM2A, B, C three-phase current detection values, k, respectively representing the first and second motors_A1、k_B1、k_C1And f_A1、f_B1、f_C1A, B, C three-phase current sensor gain error and offset error, k, respectively representing the motor set one_A2、k_B2、k_C2And f_A2、f_B2、f_C2A, B, C three-phase current sensor gain error and offset error, i, respectively representing the second motor group_PMIndicating the current detection value, k, of the DC bus current sensor_P、f_PRespectively representing the gain error and the offset error of the direct current bus current sensor;

in the formula (3), i_P1And i_P2Is shown in Table 1, wherein S₀₀₀～S₁₁₁Eight switching states, S, of the inverter 1₀₀₀'～S₁₁₁' denotes eight switching states of the inverter 2, where S₀₀₀～S₁₁₁And S₀₀₀'～S₁₁₁Subscript numbers "0" and "1" of' respectively indicate the switch states of three-phase bridge arms of the corresponding inverter A, B, C from left to right, a "0" indicates that a lower tube of the corresponding phase bridge arm is conducted and a lower tube of the corresponding phase bridge arm is not conducted, and a "1" indicates that the upper tube of the corresponding phase bridge arm is conducted and the lower tube is not conducted;

TABLE 1

On-off state

S000

S100

S110

S010

S011

S001

S101

S111

Vector of fundamental voltage

V0

V1

V2

V3

V4

V5

V6

V7

iP1

0

iA1

-iC1

iB1

-iA1

iC1

-iB1

0

On-off state

S000'

S100'

S110'

S010'

S011'

S001'

S101'

S111'

Vector of fundamental voltage

V0'

V1'

V2'

V3'

V4'

V5'

V6'

V7'

iP2

0

iA2

-iC2

iB2

-iA2

iC2

-iB2

0

The invention orthogonalizes the inverter triangular carriers of two motor sets in a motor group, as shown in fig. 2 and 3, two of the three setsThe chopping periods of the inverter are all T_sThe triangular carrier of the inverter 1 is increased forward to a half period value, i.e., T_sAt/4, the triangular carrier of the inverter 2 starts to increase from 0 in the positive direction, and by the setting method, any one inverter chopping period is positioned at T every time_s/4 or 3T_sIn the case of/4, the chopping period of the other inverter must be at the beginning of the chopping period or T_sAt/2, the voltage vector of the other inverter is just V₀(V₀') or V₇(V₇') whose bus current value i is known from Table 1_P2(i_P1) Is also exactly 0, the conclusion obtained according to the formula (3) is that the direct current bus current value i_PIs exactly equal to the bus current value i of the first inverter_P1This relationship is shown in Table 2, where i_XAnd i_X' represents a certain basic voltage vector V in the inverter 1 and the inverter 2, respectively_XAnd V_X' the inverter DC bus current value under action.

TABLE 2

As can be seen from table 2, when the inverter 1 is at its triangular carrier T_s/4 or 3T_sAt/4, the input current value i at the main terminal of the direct current bus of the motor group_POnly with a certain phase current value i of the motor group I_XIn relation to when the inverter 2 is at its triangular carrier T_s/4 or 3T_sAt/4, the input current value i at the main terminal of the direct current bus of the motor group_PIs only related to a certain phase current value of the second motor set i_X'. According to the characteristic, the invention designs the following sensor error correction strategy:

before correction, the three-phase current value used for system feedback control in each motor group in the motor group is not in conflict with the method, the three-phase feedback current value is detected by respective three-phase current sensors, and the detection point is set according to actual needs;

step 2: according to the current sampling point t shown in FIG. 2 and Table 3₁Respectively selecting 2 current sampling points which meet the conditions, namely t is met₁Time of day requested t_{1_1}、t_{1_2}Respectively sampling the values of the A-phase current sensor and the bus current sensor at the two current sampling points to obtain corresponding current values, and obtaining two defined variables delta i by using a formula (5) as shown in a formula (4)_{AM1_t1}、Δi_{PM_t1}(ii) a The method comprises the following specific steps:

a. electric machine set 1

In fig. 2 and 3, 6 time variables, t, are defined₁、t₃、t₅、t₁'、t₃'、t₅' selecting method as shown in table 3, in order to make the basic voltage vector corresponding to each time meet the relationship of table 3, the times should be set at the positions where the output voltage vector is close to the relevant basic voltage vector;

TABLE 3

Selecting two satisfying t₁Time of day requested t_{1_1}、t_{1_2}Under the action of the two time points, the current sampling values of the first motor set and the bus current sensor are respectively expressed by a formula (4):

wherein i_{AM1_t1_1}、i_{AM1_t1_2}Respectively represent t_{1_1}、t_{1_2}Sampling value i of A-phase current sensor of the two-time motor set_{A1_t1_1}、i_{A1_t1_2}Respectively representt_{1_1}、t_{1_2}True value, i, of phase A current of the two-time motor group_{PM_t1_1}、i_{PM_t1_2}Respectively represent t_{1_1}、t_{1_2}Sampling value i of bus current sensor of motor group at two moments_{P_t1_1}、i_{P_t1_2}Respectively represent t_{1_1}、t_{1_2}The real values of the bus currents of the motor groups at the two moments are respectively equal to the real values i of the A-phase currents of the motor groups at the two moments_{A1_t1_1}、i_{A1_t1_2}Equal;

t_{1_1}、t_{1_2}the selection principle of the two times is to make the difference between the corresponding current detection values larger, the step is realized by setting a relevant threshold value, and the difference is made by using each equation in the formula (4) to obtain a formula (5):

wherein Δ i_{AM1_t1}、Δi_{PM_t1}At t, the current sensor is respectively an A-phase current sensor of the motor set and a bus current sensor of the motor group_{1_1}、t_{1_2}The difference between the values detected at these two moments, the values of these two variables being available, Δ i_{A1_t1}The real value of the phase A current of the motor set is t_{1_1}、t_{1_2}The difference between these two times;

according to the current sampling point t shown in FIG. 2 and Table 3₃Respectively selecting 2 current sampling points which meet the conditions, namely t is met₃Time of day requested t_{3_1}、t_{3_2}Respectively sampling the values of the B-phase current sensor and the bus current sensor at the two current sampling points to obtain corresponding current values, and obtaining two defined variables delta i by using a formula (6)_{BM1_t3}、Δi_{PM_t3}；

According to the current sampling point t shown in FIG. 2 and Table 3₅Respectively selecting 2 current sampling points which meet the conditions, namely t is met₅Time of day requested t_{5_1}、t_{5_2}. The values of the C-phase current sensor and the bus current sensor are respectively carried out at the two current sampling pointsSampling to obtain corresponding current value, and obtaining two defined variables delta i by using formula (7)_{CM1_t5}、Δi_{PM_t5}；

The method comprises the following specific steps:

by using a similar method, the current relationship between two phases of the motor group one B, C and the relevant time is obtained, as shown in formula (6) and formula (7), wherein the definition of the relevant variables is similar to that of the phase a:

by using the formulas (5) to (7), the gain error ratio relationship between the A, B, C three-phase current sensor of the first motor group and the bus current sensor of the motor group is obtained as shown in the formula (8):

in addition, with t₁Requiring similar choices of time t₄At that time, the action vector of the inverter 1 is V₄Under the action of the time point, the current values of the A-phase and bus current sensors of the motor set are sampled, the current sampling values are respectively expressed by a formula (9), wherein the definition of related variables and t₁Similarity of time of day;

obtaining delta i by using the relevant current sampling value and combining the formula (4) and the formula (9)_{AM1PM_t1_1}And Δ i_{AM1PM_t4}The values of two variables;

wherein Δ i_{AM1PM_t1_1}Is shown at t_{1_1}Time motorThe difference value delta i of the measured current value of the current sensor of the group I A phase and the current sensor of the direct current bus of the motor group under the gain error proportionality coefficient_{AM1PM_t4}Is shown at t₄The method comprises the steps that a current sensor of a motor set A phase and a current sensor of a motor set DC bus measure the difference value of the current value under a gain error proportionality coefficient at any moment, and the two values can be obtained according to measured data;

obtaining an offset error between a motor set A-phase current sensor and a motor group direct current bus current sensor by using a formula (10), wherein the offset error is expressed by using a formula (11):

and t₃Time of day requirement selection t₆At that time, the action vector of the inverter 1 is V₆Sampling current values of a first phase B current sensor of the motor set and a bus current sensor, and obtaining a bias error of the first phase B current sensor of the motor set by applying an A phase processing method, as shown in a formula (12);

and t₅Time of day requirement selection t₂At that time, the action vector of the inverter 1 is V₂Sampling current values of a C-phase current sensor and a bus current sensor of the motor set, and obtaining a bias error of the C-phase current sensor of the motor set by applying an A-phase processing method, wherein the bias error is shown in a formula (12);

where the relevant variables and test methods are similar to those of phase a:

therefore, bias errors of all current sensors of a motor set and current sensors at the input end of a direct current bus of the motor group are eliminated, and gain errors are balanced;

b. motor set two

Similar to the method of the motor group, the bias errors of all the current sensors of the motor group and the current sensors at the input end of the direct current bus of the motor group are eliminated, and the gain errors are balanced, as shown in formula (13):

and step 3: motor group gain error cooperative correction

In the control of the motor group, the offset errors of the two motor groups related to the invention are respectively corrected by respective systems, however, the gain errors can only achieve the balance in the group, and the two motor groups need to be corrected by the system correction strategy provided by the invention, that is, the gain error ratios of 7 current sensors in total, namely 2 motor groups and a motor group direct current bus, are obtained by the first terms of the formula (8) and the formula (13) and are shown in the formula (14):

and (3) by using a formula (14), taking the bus current sensor as a reference, and proportionally and sequentially eliminating the gain error of each current sensor, wherein the elimination method is to proportionally divide the sampling current by a corresponding proportional coefficient.

Claims (2)

1. A quadrature dual-motor current sensor cooperation system based on a chopping period is characterized in that:

according to the orthogonal double-motor current sensor cooperation system based on the chopping period, in a double-motor group control system, the input voltage of an inverter direct current bus of double motors is hung at the same input port, an inverter three-phase bridge arm of each motor subsystem is correspondingly connected with a motor three-phase winding, a cable of each motor three-phase winding respectively penetrates through the corresponding current sensor signal detection port in the forward direction, the time-sharing observation of the error of the current sensor of the double motor system is realized by utilizing the relevance of the direct current bus current sensor hung by the double motor system and the three-phase current of the double motors, the current sampling error of each single motor system is estimated respectively, and finally the current sampling error cooperation correction between the multiple motor systems is realized by utilizing the observed value of the bus current.

2. A correction method using the chopping-period-based orthogonal two-motor current sensor cooperative system according to claim 1, characterized by comprising the following steps:

step 1: two motor driving groups in the double-motor group are respectively hung at the same direct-current bus end, and the detection value of the current sensor is represented by formulas (1) to (3):

wherein i_AM1、i_BM1、i_CM1And i_AM2、i_BM2、i_CM2A, B, C three-phase current detection values, k, respectively representing the first and second motors_A1、k_B1、k_C1And f_A1、f_B1、f_C1A, B, C three-phase current sensor gain error and offset error, k, respectively representing the motor set one_A2、k_B2、k_C2And f_A2、f_B2、f_C2A, B, C three-phase current sensor gain error and offset error, i, respectively representing the second motor group_PMIndicating the current detection value, k, of the DC bus current sensor_P、f_PRespectively representing the gain error and the offset error of the direct current bus current sensor;

in the formula (3), i_P1And i_P2Is shown in Table 1, wherein S₀₀₀～S₁₁₁Eight switching states, S, of the inverter 1₀₀₀'～S₁₁₁' denotes eight switching states of the inverter 2, where S₀₀₀～S₁₁₁And S₀₀₀'～S₁₁₁The subscript numbers "0" and "1" of "represent pairs from left to right, respectivelyWhen the inverter A, B, C three-phase bridge arm is in a switching state, a "0" indicates that the lower tube of the corresponding phase bridge arm is conducted and the upper tube is not conducted, and a "1" indicates that the upper tube of the corresponding phase bridge arm is conducted and the lower tube is not conducted;

TABLE 1

On-off state S₀₀₀ S₁₀₀ S₁₁₀ S₀₁₀ S₀₁₁ S₀₀₁ S₁₀₁ S₁₁₁ Vector of fundamental voltage V₀ V₁ V₂ V₃ V₄ V₅ V₆ V₇ i_P1 0 i_A1 -i_C1 i_B1 -i_A1 i_C1 -i_B1 0 On-off state S₀₀₀' S₁₀₀' S₁₁₀' S₀₁₀' S₀₁₁' S₀₀₁' S₁₀₁' S₁₁₁' Vector of fundamental voltage V₀' V₁' V₂' V₃' V₄' V₅' V₆' V₇' i_P2 0 i_A2 -i_C2 i_B2 -i_A2 i_C2 -i_B2 0

The method comprises the steps of orthogonalizing inverter triangular carriers of two motor sets in a motor group, wherein chopping periods of the two inverters are T_sThe triangular carrier of the inverter 1 is increased forward to a half period value, i.e., T_sAt the time of/4, the triangular carrier of the inverter 2 starts to increase from 0 in the positive direction, and any one inverter chopping period is positioned at T_s/4 or 3T_sIn the case of/4, the chopping period of the other inverter must be at the beginning of the chopping period or T_sAt/2, the voltage vector of the other inverter is just V₀(V₀') or V₇(V₇') whose bus current value i is known from Table 1_P2(i_P1) Is also exactly 0, the conclusion obtained according to the formula (3) is that the direct current bus current value i_PIs exactly equal to the bus current value i of the first inverter_P1This relationship is shown in Table 2, where i_XAnd i_X' represents a certain basic voltage vector V in the inverter 1 and the inverter 2, respectively_XAnd V_X' the direct current bus current value of the inverter under action;

TABLE 2

Inverter 1 triangular carrier time 0 T_s/4 T_s/2 3T_s/4 Inverter 1 fundamental voltage vector V₀ V_X V₇ V_X i_P1 0 i_X 0 i_X Inverter 2 triangular carrier time 3T_s/4 0 T_s/4 T_s/2 Inverter 2 fundamental voltage vector V_X' V₀' V_X' V₇' i_P2 i_X' 0 i_X' 0 i_P i_X' i_X i_X' i_X

As can be seen from table 2, when the inverter 1 is at its triangular carrier T_s/4 or 3T_sAt/4, the input current value i at the main terminal of the direct current bus of the motor group_POnly with a certain phase current value i of the motor group I_XIn relation to when the inverter 2 is at its triangular carrier T_s/4 or 3T_sAt/4, the input current value i at the main terminal of the direct current bus of the motor group_PIs only related to a certain phase current value of the second motor set i_X'；

The sensor error correction strategy is as follows:

before correction, in each motor group in the motor group, three-phase feedback current values are obtained by detection of respective three-phase current sensors, and detection points of the three-phase feedback current values can be set according to actual requirements;

step 2: according to current sampling point t₁Respectively selecting 2 current sampling points which meet the conditions, namely t is met₁Time of day requested t_{1_1}、t_{1_2}Respectively sampling the values of the A-phase current sensor and the bus current sensor at two current sampling points to obtain corresponding current values, and obtaining two defined variables by using a formula (5) as shown in a formula (4)Δi_{AM1_t1}、Δi_{PM_t1}(ii) a The method comprises the following specific steps:

a. electric machine set 1

Defining 6 time variables, t₁、t₃、t₅、t₁'、t₃'、t₅' selecting method as shown in table 3, in order to make the basic voltage vector corresponding to each time meet the relationship of table 3, the times should be set at the positions where the output voltage vector is close to the relevant basic voltage vector;

TABLE 3

Selecting two satisfying t₁Time of day requested t_{1_1}、t_{1_2}Under the action of the two time points, the current sampling values of the first motor set and the bus current sensor are respectively expressed by a formula (4):

wherein i_{AM1_t1_1}、i_{AM1_t1_2}Respectively represent t_{1_1}、t_{1_2}Sampling value i of A-phase current sensor of the two-time motor set_{A1_t1_1}、i_{A1_t1_2}Respectively represent t_{1_1}、t_{1_2}True value, i, of phase A current of the two-time motor group_{PM_t1_1}、i_{PM_t1_2}Respectively represent t_{1_1}、t_{1_2}Sampling value i of bus current sensor of motor group at two moments_{P_t1_1}、i_{P_t1_2}Respectively represent t_{1_1}、t_{1_2}The real values of the bus currents of the motor groups at the two moments are respectively equal to the real values i of the A-phase currents of the motor groups at the two moments_{A1_t1_1}、i_{A1_t1_2}Equal;

t_{1_1}、t_{1_2}the two times are selected by setting relative threshold values according to the principle that the difference between the corresponding current detection values is large, and each time in the formula (4) is usedThe equation is subtracted to obtain formula (5):

wherein Δ i_{AM1_t1}、Δi_{PM_t1}At t, the current sensor is respectively an A-phase current sensor of the motor set and a bus current sensor of the motor group_{1_1}、t_{1_2}The difference between the values detected at these two moments, the values of these two variables being available, Δ i_{A1_t1}The real value of the phase A current of the motor set is t_{1_1}、t_{1_2}The difference between these two times;

according to current sampling point t₃Respectively selecting 2 current sampling points which meet the conditions, namely t is met₃Time of day requested t_{3_1}、t_{3_2}Respectively sampling the values of the B-phase current sensor and the bus current sensor at two current sampling points to obtain corresponding current values, and obtaining two defined variables delta i by using a formula (6)_{BM1_t3}、Δi_{PM_t3}；

According to current sampling point t₅Respectively selecting 2 current sampling points which meet the conditions, namely t is met₅Time of day requested t_{5_1}、t_{5_2}Respectively sampling the values of the C-phase current sensor and the bus current sensor at the two current sampling points to obtain corresponding current values, and obtaining two defined variables delta i by using a formula (7)_{CM1_t5}、Δi_{PM_t5}；

The method comprises the following specific steps:

by using a similar method, the current relationship between two phases of the motor group one B, C and the relevant time is obtained, as shown in formula (6) and formula (7), wherein the definition of the relevant variables is similar to that of the phase a:

by using the formulas (5) to (7), the gain error ratio relationship between the A, B, C three-phase current sensor of the first motor group and the bus current sensor of the motor group is obtained as shown in the formula (8):

in addition, with t₁Requiring similar choices of time t₄At that time, the action vector of the inverter 1 is V₄Under the action of the time point, the current values of the A-phase and bus current sensors of the motor set are sampled, the current sampling values are respectively expressed by a formula (9), wherein the definition of related variables and t₁Similarity of time of day;

obtaining delta i by using the relevant current sampling value and combining the formula (4) and the formula (9)_{AM1PM_t1_1}And Δ i_{AM1PM_t4}The values of two variables;

wherein Δ i_{AM1PM_t1_1}Is shown at t_{1_1}The difference value delta i of the measured current value of a current sensor of an A-phase of the motor group and a current sensor of a direct current bus of the motor group under the gain error proportionality coefficient at the moment_{AM1PM_t4}Is shown at t₄The method comprises the steps that a current sensor of a motor set A phase and a current sensor of a motor set DC bus measure the difference value of the current value under a gain error proportionality coefficient at any moment, and the two values can be obtained according to measured data;

obtaining an offset error between a motor set A-phase current sensor and a motor group direct current bus current sensor by using a formula (10), wherein the offset error is expressed by using a formula (11):

and t₃Time of day requirement selection t₆At that time, the action vector of the inverter 1 is V₆Sampling current values of a first phase B current sensor of the motor set and a bus current sensor, and obtaining a bias error of the first phase B current sensor of the motor set by applying an A phase processing method, as shown in a formula (12);

and t₅Time of day requirement selection t₂At that time, the action vector of the inverter 1 is V₂Sampling current values of a C-phase current sensor and a bus current sensor of the motor set, and obtaining a bias error of the C-phase current sensor of the motor set by applying an A-phase processing method, wherein the bias error is shown in a formula (12);

where the relevant variables and test methods are similar to those of phase a:

therefore, bias errors of all current sensors of a motor set and current sensors at the input end of a direct current bus of the motor group are eliminated, and gain errors are balanced;

b. motor set two

Similar to the method of the motor group, the bias errors of all the current sensors of the motor group and the current sensors at the input end of the direct current bus of the motor group are eliminated, and the gain errors are balanced, as shown in formula (13):

and step 3: motor group gain error cooperative correction

In two motor sets involved in motor group control, offset errors are corrected by respective systems, however, gain errors can only achieve balance in the sets, and the two motor sets need to be corrected by a system correction strategy, that is, by using the first terms of formula (8) and formula (13), the gain error ratios of 7 current sensors including 2 motor sets and a motor group direct current bus are obtained as shown in formula (14):

and (3) by using a formula (14), taking the bus current sensor as a reference, and proportionally and sequentially eliminating the gain error of each current sensor, wherein the elimination method is to proportionally divide the sampling current by a corresponding proportional coefficient.

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