阅读说明：本技术 基于斩波周期移相电机群电流传感器协同系统及校正方法 (Phase-shift motor group current sensor cooperation system based on chopping period and correction method ) 是由 鲁家栋 胡义华 王洁 倪锴 于 2020-02-13 设计创作，主要内容包括：本发明提供了一种基于斩波周期移相电机群电流传感器协同系统及校正方法,在电机群控制系统中,将多电机子系统的变频器输入电源端口统一挂靠在同一个直流母线电压输入端子,将每一个电机子系统的逆变器三相桥臂中点分别与对应的电机三相绕组相连,将每一个电机三相绕组线缆分别正向穿过相应的电流传感器信号检测口,实现多电机子系统电流传感器误差的分时校正,实现电机群多电机子系统之间的电流采样误差协同校正。本发明的误差校正所需控制算法简单易实现,不需要其他传感器信息,稳定性更好,可以实现电机群多电机子系统电流采样误差的协同校正。(The invention provides a phase-shift motor group current sensor cooperative system based on a chopping period and a correction method. The control algorithm required by the error correction is simple and easy to realize, other sensor information is not required, the stability is better, and the cooperative correction of the current sampling errors of the multiple motor subsystems of the motor group can be realized.)

1. A phase-shifting motor group current sensor cooperation system based on a chopping period is characterized in that:

according to the phase-shift motor group current sensor cooperative system based on the chopping period, in a motor group control system, a frequency converter input power port of a multi-motor subsystem is uniformly hung on the same direct-current bus voltage input terminal, the middle point of an inverter three-phase bridge arm of each motor subsystem is respectively connected with a corresponding motor three-phase winding, each motor three-phase winding cable respectively penetrates through a corresponding current sensor signal detection port in the forward direction, time-sharing correction of current sensor errors of the multi-motor subsystem is achieved by utilizing the relevance of the current of the multi-motor subsystem of the motor group and the direct-current bus, and finally, the current sampling errors among the multi-motor subsystem of the motor group are cooperatively corrected by utilizing the relevance of the current signals of the multi-motor subsystem.

2. A correction method for the current sensor cooperation system of the phase-shifting motor group based on the chopping period according to claim 1 is characterized by comprising the following steps:

step 1: respectively attaching inverter power input ends of a plurality of motor subsystems in a motor group to the same direct current bus end, considering sampling errors in a current sampling loop, and expressing current detection values by a formula (1) and a formula (2), wherein i_AMx、i_BMx、i_CMxA, B, C three-phase current detection values of a motor group x are respectively represented, wherein x is 1_Ax、k_Bx、k_CxAnd f_Ax、f_Bx、f_CxA, B, C three-phase current sensor gain error and offset error, i, respectively, representing the motor set x_PMIndicating the current detection value, k, of the DC bus current sensor_P、f_PRespectively, the gain error and the offset error of the direct current bus current sensor are shown as follows:

the triangular carriers of the n motor subsystems are initially in phase, and when a correction command comes, the next chopping period of the inverter 1 of the motor subsystem 1 is firstly adjusted to 5T_sStep 4, enabling the frequency converter 1 to perform phase shifting;

step 2: then the subsequent chopping period of the inverter 1 of the motor subsystem 1 is adjusted to T_sCorrecting the sampling error of the current sensor of the first motor set by using the current value at the relevant current sampling point;

and step 3: subsequently, the next three continuous chopping cycles of the inverter 1 of the motor subsystem 1 are adjusted to 5T_sStep 4, enabling the inverter 1 to shift the phase and return;

and 4, step 4: finally, the subsequent chopping period of the inverter 1 of the motor subsystem 1 is adjusted to T again_sReturning the motor group system to an initial state;

and 5: and cooperatively correcting current sampling errors of each motor subsystem of the motor group.

3. The correction method of the current sensor cooperative system based on the chopping cycle phase-shifting motor group according to claim 2, characterized in that:

the correction step of the step 2 is as follows:

when the inverter is turned on1 is at T_sIn the/4 period, the chopping periods of the rest n-1 inverters are all at T_sAt the position of a/2 period, according to a seven-segment SVPWM modulation method, when the chopping periods of the inverter x are all at T_sIn the/2 cycle, the applied basic voltage vector is a zero voltage vector, namely V₀Or V₇And at this time, the input current value i of the inverter x_PxEqual to 0; therefore, when the chopping period of the inverter 1 is at T_sIn the period of/4, the input current values of the rest n-1 inverters are all 0, as shown in the formula (3), and at the moment, the input current value i of the direct current bus end of the motor group is_PWith the input current i of the inverter 1 of the motor group 1_P1And (3) equality:

input current value i of direct current bus terminal of motor group_PNamely, the input end current i of the inverter 1 of the motor set 1 can be replaced_P1Correcting the current sensor error of the motor subsystem 1; 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 are set according to actual requirements; the number of chopping cycles is not 3, but is determined according to actual conditions;

setting 9 effective current sampling points t by using' current sampling point setting method_x(x ═ 1,. 6,1',3',5') and samples the desired current values in table 1; the current sampling point setting method comprises the following steps:

when the inverter 1 is at T in each chopping cycle_sAnd when the current sampling error of the motor group is corrected, setting the moment as sampling points, wherein each sampling point is not an effective sampling point, and the total number of the effective sampling points of the motor group current sampling error cooperative correction method is 9, wherein the effective sampling points are respectively as follows: when the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₁When the phase angle is not more than 10 deg., i.e. T is satisfied in sector I₁>>T₂Satisfies T in sector VI₁>>T₆According to the A-phase current value of the motor subsystem 1Size, two i are selected_AM1The point with the difference value larger than 25 percent of rated current is taken as 2 effective sampling points t of A-phase current₁，t₁'; when the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₃Then, two i phases are selected according to the B phase current value of the motor subsystem 1_BM1The point with the difference value larger than 25 percent of rated current is taken as 2 effective sampling points t of the B-phase current₃，t₃'; when the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₅Selecting two i phases according to the C phase current value of the motor subsystem 1_CM1The point with the difference value larger than 25 percent of rated current is taken as the effective sampling point t of 2C-phase currents₅，t₅'; in addition, when the inverter 1 output voltage vector of the motor subsystem 1 approaches the basic voltage vector V₄Then, select the 3 rd effective sampling point t of A phase current₄(ii) a When the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₆Then, select the 3 rd effective sampling point t of phase B current₆(ii) a When the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₂Then, select the 3 rd C phase current effective sampling point t₂(ii) a At 9 effective current sampling points, the three-phase current i of the motor subsystem 1_AM1、i_BM1、i_CM1And the DC bus current i of the motor group_PMThe relationship between the magnitude of the detected value and 9 effective current sampling points is shown in Table 1, wherein i_{A1_t1}、i_{A1_t1'}、i_{A1_t4}Respectively, at t, the A-phase current of the motor subsystem 1₁、t₁'、t₄Actual values at three effective current sampling points, i_{B1_t3}、i_{B1_t3'}、i_{B1_t6}Respectively, the phase B current of the motor subsystem 1 is shown at t₃、t₃'、t₆Actual values at three effective current sampling points, i_{C1_t5}、i_{C1_t5'}、i_{C1_t2}Respectively, the phase C current of the motor subsystem 1 is shown at t₅、t₅'、t₂Actual values at three effective current sampling points, i_{AM1_tx}、i_{BM1_tx}、i_{CM1_tx}、i_{PM_tx}Respectively representing electric motorsA, B, C three-phase current of system 1 and bus current of motor group at effective current sampling point t_xA detected value of (x ═ 1,.., 6,1',3',5 ');

TABLE 1

According to the 9 effective current sampling points and the corresponding 18 current sampling signals in the table 1, a plurality of variables defined by the formula (4) are obtained, wherein, delta 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 group₁、t₁' the difference between the values detected at these two times, the values of the two variables being calculated using the current sample values, [ Delta ] i_{A1_t1}The real value of the phase A current of the motor set is t₁、t₁' difference between these two moments,. DELTA.i_{BM1_t3}、Δi_{PM_t3}A B-phase current sensor of the motor set and a bus current sensor of the motor group are respectively arranged at t₃、t₃' the difference between the values detected at these two moments, the values of the two variables being available,. DELTA.i_{B1_t3}The real value of the phase B current of the motor set is t₃、t₃' difference between these two moments,. DELTA.i_{CM1_t5}、Δi_{PM_t5}A C-phase current sensor of the motor set and a bus current sensor of the motor group are respectively arranged at t₅、t₅' the difference between the values detected at these two moments, the values of the two variables being available,. DELTA.i_{C1_t5}The real value of the current of the phase C of the motor set is t₅、t₅' difference of these two moments:

according to the formula (4), the proportional relation of the gain errors of the motor group I A, B, C three-phase current sensor and the motor group bus current sensor is obtained and is shown in the formula (5):

combining the formula (4) and the formula (5), a plurality of new variables are defined, as shown in the formula (6):

wherein Δ i_{AM1PM_t1}Is shown at t₁The 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 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_{BM1PM_t3}Is shown at t₃The difference value delta i of the current value measured by a current sensor of a phase B of the motor set and a current sensor of a direct current bus of the motor set under the gain error proportionality coefficient at the moment_{BM1PM_t6}Is shown at t₆The difference value delta i of the current value measured by a current sensor of a phase B of the motor set and a current sensor of a direct current bus of the motor set under the gain error proportionality coefficient at the moment_{CM1PM_t5}Is shown at t₅The difference value delta i of the current value measured by a current sensor of a C-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_{CM1PM_t2}Is shown at t₂A C-phase current sensor of the motor set and a direct-current bus current sensor of the motor set measure the difference value of the current value under the gain error proportionality coefficient at the moment;

by using the formula (6), the offset error between the current sensor of the motor set one A, B, C phase and the current sensor of the direct current bus of the motor group is finally obtained as shown in the formula (7):

therefore, sampling errors of all current sensors of the motor subsystem 1 and the direct current bus current sensors of the motor group are finally eliminated.

4. The correction method of the current sensor cooperative system based on the chopping cycle phase-shifting motor group according to claim 2, characterized in that:

in the step 5, the chopping periods of n inverters of the system finally return to the initial state from the initial state, then the chopping periods of the n inverters 2, a.

According to a current sampling error correction method of the motor subsystem 1 and a chopping period sequential phase shifting method, current sampling errors of the rest n-1 motor subsystems are eliminated, bias errors of all current sensors of the motor group are finally eliminated, gain error relations of all current sensors of each motor subsystem are obtained, and gain error coefficients of the current sensors of the direct current bus of the motor group are utilized to finally achieve cooperative elimination of the gain errors.

Technical Field

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

Background

The motor group control is one of the important future development directions in the field of motor system control, and particularly, the motor group control is particularly important in the application field where a plurality of motors need to be cooperatively controlled. An important problem faced by the control of the motor group is that the sensing or detection precision of each motor subsystem to the feedback variable is inconsistent, so that the performance of each motor subsystem is not completely unified, and finally, the control of the whole motor group cannot reach the expected control target. In modern motor control systems, current information is an extremely important feedback quantity of the system, and is an indispensable key information for the motor system to achieve the control target of the motor system no matter in a conventional driving system, including vector control, direct torque control and the like, or a control method used in special application fields such as position sensor-free control and the like. The current sampling loop of the motor control system mainly comprises a current sensor, a modulation resistor, an operational amplifier, a voltage reference and the like, and is influenced by a plurality of factors such as operating conditions, environment, aging and the like in practical use, the current sampling loops inevitably generate sampling errors, the errors among a plurality of sampling loops of a single motor subsystem are different, and the sampling errors are introduced into the control system, so that adverse effects such as unbalanced three-phase current, torque pulsation, rotating speed fluctuation, system noise and the like can be brought to the system. And aiming at the control of the motor group, sampling errors contained in different motor subsystems are different, so that the control performance of each subsystem tends to be uncoordinated, and the control target of the control of the motor group is influenced finally. At present, a correction method for a current sampling error of a motor system is mainly realized by using a system variable observation method, using a rotating speed or position sensor, and combining complex control algorithms such as a digital filter, an observer and the like [ documents 1 to 3 are recorded, and document 1 is Hao Yan, Yongxiang Xu, Weiduo Zhao, He Zhang, Chris Gerada, "DCdrift error determination method for three-phase current detection with single hall sensor"

IEEE Transactions on Magnetics, vol.55, No.2, pp.8100604, Feb.2019 (journal articles), Quoc Nam Trinh, Peng Wang, Yi Tang, L eong Hai Koh, Fook Hoong Choo,

the present invention relates to a method for correcting motor position errors, and more particularly to a method for correcting motor position errors, which comprises the steps of "Compensation of DC offset and scaling sensors in voltage and current sensors," IEEE Transactions on power Electronics, vol.33, No.6, pp. 5401-5414, jun.2018 (journal article), document 3 Kwang-Woon L ee, "Sang-Il Kim," Dynamic property improvement of a current dependent resistor in current-controlled spmm drivers, "IEEE Transactions on industrial Electronics, vol.66, No.9, pp.6727-6736, sep. (journal article), which are applied to motors, and which can not be applied to a group of motors.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a phase-shifting motor group current sensor cooperative system based on a chopping period and a correction method. In order to solve the problem that current sampling errors are difficult to eliminate in the field of multi-motor cooperative control, a plurality of motor subsystems are hung at the input end of a same direct-current bus power supply, the current sampling errors of the motor subsystems are eliminated by performing time-sharing phase-shifting control on the chopping cycles of the motor subsystems, and finally the error cooperative correction among the motor subsystems is realized by utilizing the relevance among the multi-motor subsystems, so that the accurate control of the motor group system control is finally ensured, the required calculation amount is small, and the implementation method is simple.

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

a phase-shift motor group current sensor cooperative system based on a chopping period is characterized in that in a motor group control system, input power ports of frequency converters of multiple motor subsystems are uniformly hung on the same direct-current bus voltage input terminal, the middle points of inverter three-phase bridge arms of each motor subsystem are respectively connected with corresponding motor three-phase windings, cables of each motor three-phase winding respectively penetrate through corresponding current sensor signal detection ports in the forward direction, time-sharing correction of current sensor errors of the multiple motor subsystems is achieved by utilizing the relevance of the current of the multiple motor subsystems of a motor group and the direct-current bus, and finally, the current sampling errors among the multiple motor subsystems of the motor group are cooperatively corrected by utilizing the relevance of the current signals of the multiple motor subsystems.

The invention also provides a correction method of the phase-shift motor group current sensor cooperative system based on the chopping period, which comprises the following specific steps:

step 1: respectively attaching inverter power input ends of a plurality of motor subsystems in a motor group to the same direct current bus end, considering sampling errors in a current sampling loop, and expressing current detection values by a formula (1) and a formula (2), wherein i_AMx、i_BMx、i_CMxA, B, C three-phase current detection values of a motor group x are respectively represented, wherein x is 1_Ax、k_Bx、k_CxAnd f_Ax、f_Bx、f_CxA, B, C three-phase current sensor gain error and offset error, i, respectively, representing the motor set x_PMIndicating the current detection value, k, of the DC bus current sensor_P、f_PRespectively, the gain error and the offset error of the direct current bus current sensor are shown as follows:

the triangular carriers of the n motor subsystems are initially in phase, and when a correction command comes, the next chopping period of the inverter 1 of the motor subsystem 1 is firstly adjusted to 5T_s/4, changing intoThe frequency shifter 1 performs phase shifting;

step 2: then the subsequent chopping period of the inverter 1 of the motor subsystem 1 is adjusted to T_sCorrecting the sampling error of the current sensor of the first motor set by using the current value at the relevant current sampling point;

and step 3: subsequently, the next three continuous chopping cycles of the inverter 1 of the motor subsystem 1 are adjusted to 5T_sStep 4, enabling the inverter 1 to shift the phase and return;

and 4, step 4: finally, the subsequent chopping period of the inverter 1 of the motor subsystem 1 is adjusted to T again_sReturning the motor group system to an initial state;

and 5: and cooperatively correcting current sampling errors of each motor subsystem of the motor group.

The correction step of the step 2 is as follows:

when the chopping period of the inverter 1 is at T_sIn the/4 period, the chopping periods of the rest n-1 inverters are all at T_sAt the position of a/2 period, according to a seven-segment SVPWM modulation method, when the chopping periods of the inverter x are all at T_sIn the/2 cycle, the applied basic voltage vector is a zero voltage vector, namely V₀Or V₇And at this time, the input current value i of the inverter x_PxEqual to 0; therefore, when the chopping period of the inverter 1 is at T_sIn the period of/4, the input current values of the rest n-1 inverters are all 0, as shown in the formula (3), and at the moment, the input current value i of the direct current bus end of the motor group is_PWith the input current i of the inverter 1 of the motor group 1_P1And (3) equality:

input current value i of direct current bus terminal of motor group_PNamely, the input end current i of the inverter 1 of the motor set 1 can be replaced_P1Correcting the current sensor error of the motor subsystem 1; 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 are set according to actual requirements; number of chopping cycles andis not 3, but is determined according to actual conditions;

setting 9 effective current sampling points t by using' current sampling point setting method_x(x ═ 1,. 6,1',3',5') and samples the desired current values in table 1; the current sampling point setting method comprises the following steps:

when the inverter 1 is at T in each chopping cycle_sAnd when the current sampling error of the motor group is corrected, setting the moment as sampling points, wherein each sampling point is not an effective sampling point, and the total number of the effective sampling points of the motor group current sampling error cooperative correction method is 9, wherein the effective sampling points are respectively as follows: when the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₁When the phase angle is not more than 10 deg., i.e. T is satisfied in sector I₁>>T₂Satisfies T in sector VI₁>>T₆Selecting two i according to the A phase current value of the motor subsystem 1_AM1The point with the difference value larger than 25 percent of rated current is taken as 2 effective sampling points t of A-phase current₁，t₁'; when the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₃Then, two i phases are selected according to the B phase current value of the motor subsystem 1_BM1The point with the difference value larger than 25 percent of rated current is taken as 2 effective sampling points t of the B-phase current₃，t₃'; when the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₅Selecting two i phases according to the C phase current value of the motor subsystem 1_CM1The point with the difference value larger than 25 percent of rated current is taken as the effective sampling point t of 2C-phase currents₅，t₅'; in addition, when the inverter 1 output voltage vector of the motor subsystem 1 approaches the basic voltage vector V₄Then, select the 3 rd effective sampling point t of A phase current₄(ii) a When the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₆Then, select the 3 rd effective sampling point t of phase B current₆(ii) a When the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₂Then, select the 3 rd C phase current effective sampling point t₂(ii) a At 9 effective current sampling points, the three-phase current i of the motor subsystem 1_AM1、i_BM1、i_CM1And the DC bus current i of the motor group_PMThe relationship between the magnitude of the detected value and 9 effective current sampling points is shown in Table 1, wherein i_{A1_t1}、i_{A1_t1'}、i_{A1_t4}Respectively, at t, the A-phase current of the motor subsystem 1₁、 t₁'、t₄Actual values at three effective current sampling points, i_{B1_t3}、i_{B1_t3'}、i_{B1_t6}Respectively, the phase B current of the motor subsystem 1 is shown at t₃、t₃'、t₆Actual values at three effective current sampling points, i_{C1_t5}、i_{C1_t5'}、i_{C1_t2}Respectively, the phase C current of the motor subsystem 1 is shown at t₅、t₅'、t₂Actual values at three effective current sampling points, i_{AM1_tx}、i_{BM1_tx}、i_{CM1_tx}、 i_{PM_tx}A, B, C three-phase current of the motor subsystem 1 and the bus current of the motor group at an effective current sampling point t_xA detected value of (x ═ 1,.., 6,1',3',5 ');

TABLE 1

According to the 9 effective current sampling points and the corresponding 18 current sampling signals in the table 1, a plurality of variables defined by the formula (4) are obtained, wherein, delta 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 group₁、t₁' the difference between the values detected at these two times, the values of the two variables being calculated using the current sample values, [ Delta ] i_{A1_t1}The real value of the phase A current of the motor set is t₁、t₁' difference between these two moments,. DELTA.i_{BM1_t3}、Δi_{PM_t3}A B-phase current sensor of the motor set and a bus current sensor of the motor group are respectively arranged at t₃、t₃' the difference between the detected values at these two times, two variablesThe value of (a) is obtainable,. DELTA.i_{B1_t3}The real value of the phase B current of the motor set is t₃、t₃' difference between these two moments,. DELTA.i_{CM1_t5}、Δi_{PM_t5}A C-phase current sensor of the motor set and a bus current sensor of the motor group are respectively arranged at t₅、t₅' the difference between the values detected at these two moments, the values of the two variables being available,. DELTA.i_{C1_t5}The real value of the current of the phase C of the motor set is t₅、t₅' difference of these two moments:

according to the formula (4), the proportional relation of the gain errors of the motor group I A, B, C three-phase current sensor and the motor group bus current sensor is obtained and is shown in the formula (5):

combining the formula (4) and the formula (5), a plurality of new variables are defined, as shown in the formula (6):

wherein Δ i_{AM1PM_t1}Is shown at t₁The 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 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_{BM1PM_t3}Is shown at t₃The difference value delta i of the current value measured by a current sensor of a phase B of the motor set and a current sensor of a direct current bus of the motor set under the gain error proportionality coefficient at the moment_{BM1PM_t6}Is shown at t₆The difference value delta i of the current value measured by a current sensor of a phase B of the motor set and a current sensor of a direct current bus of the motor set under the gain error proportionality coefficient at the moment_{CM1PM_t5}Is shown at t₅The difference value delta i of the current value measured by a current sensor of a C-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_{CM1PM_t2}Is shown at t₂A C-phase current sensor of the motor set and a direct-current bus current sensor of the motor set measure the difference value of the current value under the gain error proportionality coefficient at the moment;

by using the formula (6), the offset error between the current sensor of the motor set one A, B, C phase and the current sensor of the direct current bus of the motor group is finally obtained as shown in the formula (7):

therefore, sampling errors of all current sensors of the motor subsystem 1 and the direct current bus current sensors of the motor group are finally eliminated.

In the step 5, the chopping periods of n inverters of the system finally return to the initial state from the initial state, then the chopping periods of the n inverters 2, a.

According to a current sampling error correction method of the motor subsystem 1 and a chopping period sequential phase shifting method, current sampling errors of the rest n-1 motor subsystems are eliminated, bias errors of all current sensors of the motor group are finally eliminated, gain error relations of all current sensors of each motor subsystem are obtained, and gain error coefficients of the current sensors of the direct current bus of the motor group are utilized to finally achieve cooperative elimination of the gain errors.

The invention has the advantages that aiming at the problem of error correction of the current sensor of the motor group control, in particular to the AC frequency conversion multi-motor cooperative control system, the invention has the following advantages:

(1) the control algorithm required by the invention for realizing the current sampling error correction of the multi-motor subsystem of the motor group is simple and easy to realize: the existing scheme adopts a control algorithm which takes the whole motor subsystem as a correction loop of the motor subsystem, analyzes signals fed back by a position or rotating speed sensor by utilizing characteristics of adverse influence of current sampling errors on the system, such as rotating speed fluctuation and the like, and finally obtains the current sampling errors through complex algorithms such as an observer, a digital filter and the like, so that not only is the calculation burden of the system increased, but also the implementability of other complex algorithms is possibly influenced;

(2) the invention realizes the current sampling error correction of the multi-motor subsystem of the motor group without other sensor information, and has better stability: in the prior scheme, each motor subsystem is required to be used as a loop for realizing current sampling error correction, the single motor subsystem current sampling error correction target is realized by means of a position or rotating speed sensor, the control of the distinction between rotating speed fluctuation and rotating speed fluctuation caused by the current sampling error is difficult to realize under the dynamic operation of the system, the correction effect under the dynamic working condition is not good, in addition, the position or rotating speed sensor error is also a potential uncertain factor for the correction effect, the correction stability is difficult to guarantee, the multi-motor current sampling error collaborative correction method based on the time-sharing phase shift of each motor subsystem in the wave-occupying period adopted in the scheme does not need to use the whole system as a correction loop, the collaborative correction of the current sampling error can be realized only by depending on a current sampling value, and the dynamic working condition effect and the correction;

(3) the invention can realize the cooperative correction of the current sampling error of the multi-motor subsystem of the motor group: the existing scheme is provided for a single motor subsystem, and can realize the correction of current sampling errors of each single motor subsystem, but the control of a motor group comprising multiple motor subsystems is an integral body, and the existing scheme can not balance the sampling errors among the subsystems, so that the error cooperative correction among the multiple motor subsystems of the motor group can not be realized, and the integral control effect of the motor group can not be ensured.

Drawings

FIG. 1 is a schematic diagram of the error co-correction scheme of the current sensor of the motor group according to the present invention.

Fig. 2 is a schematic diagram of the error correction scheme of the current sensor of the motor group motor 1 subsystem.

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_P2、i_PnInput forward currents i of the inverter 1, the inverter 2 and the inverter n, 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 values i of the second motor set_An、i_Bn、i_CnRespectively A, B, C three-phase real current value, T, of the motor group n_sIs the switching period of the inverter.

Detailed Description

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

A phase-shift motor group current sensor cooperative system based on a chopping period is characterized in that in a motor group control system, input power ports of frequency converters of multiple motor subsystems are uniformly hung on the same direct-current bus voltage input terminal, the middle points of inverter three-phase bridge arms of each motor subsystem are respectively connected with corresponding motor three-phase windings, cables of each motor three-phase winding respectively penetrate through corresponding current sensor signal detection ports in the forward direction, the relevance between the multiple motor subsystems of a motor group and the direct-current bus current is utilized, the chopping time-sharing phase-shift control method of each motor subsystem is combined, the time-sharing correction of current sensor errors of the multiple motor subsystems is realized, and finally the current sampling error cooperative correction between the multiple motor subsystems of the motor group is realized by utilizing the relevance of the current signals of the multiple motor subsystems.

The correction method of the phase-shifting motor group current sensor cooperative system based on the chopping period comprises the following steps:

step 1: in fig. 1, inverter power input ends of a plurality of motor subsystems in a motor group are respectively hung at the same direct current bus end, sampling errors in a current sampling loop are considered, and current detection values are expressed by formula (1) and formula (2), wherein i_AMx、i_BMx、i_CMxA, B, C three-phase current detection values of a motor group x are respectively represented, wherein x is 1_Ax、k_Bx、k_CxAnd f_Ax、f_Bx、f_CxA, B, C three-phase current sensor gain error and offset error, i, respectively, representing the motor set x_PMIndicating the current detection value, k, of the DC bus current sensor_P、 f_PRespectively, the gain error and the offset error of the direct current bus current sensor are shown as follows:

the steps of the implementation of the present invention are as shown in fig. 2, the triangular carriers of n motor subsystems are initially in phase, when the correction command comes, the next chopping cycle of the inverter 1 of the motor subsystem 1 is first adjusted to 5T_sAnd/4, the frequency converter 1 is phase-shifted, as in step ① in figure 2,

step 2: then the subsequent chopping period of the inverter 1 of the motor subsystem 1 is adjusted to T_sUsing the associated electricityThe current value at the current sampling point corrects for the current sensor sampling error of motor group one, step ② in fig. 2.

In step ② shown in FIG. 2, it is seen that inverter 1 has a chopping period that lags behind T compared to the other n-1 inverters_s/4, therefore, when the chopping period of the inverter 1 is at T_sIn the/4 period, the chopping periods of the rest n-1 inverters are all at T_sAt period/2. According to the seven-segment SVPWM modulation method, when the chopping periods of the inverter x are all at T_sIn the/2 cycle, the applied basic voltage vector is a zero voltage vector, namely V₀Or V₇And at this time, the input current value i of the inverter x_PxEqual to 0. Therefore, when the chopping period of the inverter 1 is at T_sIn the period of/4, the input current values of the rest n-1 inverters are all 0, as shown in the formula (3), and at the moment, the input current value i of the direct current bus end of the motor group is_PWith the input current i of the inverter 1 of the motor group 1_P1And (3) equality:

therefore, in step ② shown in FIG. 2, the motor cluster DC bus input current value i is used_PNamely, the input end current i of the inverter 1 of the motor set 1 can be replaced_P1Before the correction, in each motor group in the motor group, the three-phase current value used for the system feedback control does not conflict with the present invention, the three-phase feedback current value is detected by the respective three-phase current sensor, and the detection point can be set according to the actual requirement, and the chopping cycle number included in the step ② is not 3, but is determined according to the actual situation, and is only a schematic diagram in fig. 2.

Setting 9 effective current sampling points t by using' current sampling point setting method_x(x ═ 1,.., 6,1',3',5') and the desired current values in table 1 were sampled.

The current sampling point setting method comprises the following steps: when the inverter 1 is at T in each chopping cycle_sIn the case of/4, the moment is set as a sampling point, but not every sampling point is an effective sampling point, the total number of the effective sampling points of the motor group current sampling error collaborative correction method adopted by the invention needs 9, which are respectively: when the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₁When (the phase angle differs by no more than 10 deg., i.e. T is satisfied in sector I₁>>T₂Satisfies T in sector VI₁>>T₆) Selecting two i according to the A phase current value of the motor subsystem 1_AM1The point with the difference value larger than 25 percent of rated current is taken as 2 effective sampling points t of A-phase current₁，t₁'; according to a similar principle, when the inverter 1 output voltage vector of the motor subsystem 1 approaches the basic voltage vector V₃Then, two i phases are selected according to the B phase current value of the motor subsystem 1_BM1The point of difference value larger than 25% rated current is taken as 2 effective sampling points t of B-phase current₃，t₃'; when the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₅Selecting two i phases according to the C phase current value of the motor subsystem 1_CM1The point with the difference value larger than 25 percent of rated current is taken as the effective sampling point t of 2C-phase currents₅，t₅'. In addition, when the inverter 1 output voltage vector of the motor subsystem 1 approaches the basic voltage vector V₄Then, select the 3 rd effective sampling point t of A phase current₄(ii) a When the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₆Then, select the 3 rd effective sampling point t of phase B current₆(ii) a When the output voltage vector of the inverter 1 of the motor subsystem 1 approaches the basic voltage vector V₂Then, select the 3 rd C phase current effective sampling point t₂. At the 9 effective sampling points of the current, the three-phase current i of the motor subsystem 1_AM1、i_BM1、 i_CM1And the DC bus current i of the motor group_PMThe relationship between the magnitude of the detected value and 9 effective current sampling points is shown in Table 1, wherein i_{A1_t1}、i_{A1_t1'}、i_{A1_t4}Respectively, at t, the A-phase current of the motor subsystem 1₁、t₁'、t₄Actual values at three effective current sampling points, i_{B1_t3}、i_{B1_t3'}、i_{B1_t6}Respectively, the phase B current of the motor subsystem 1 is shown at t₃、 t₃'、t₆Actual values at three effective current sampling points, i_{C1_t5}、i_{C1_t5'}、i_{C1_t2}Respectively, the phase C current of the motor subsystem 1 is shown at t₅、t₅'、t₂Actual values at three effective current sampling points, i_{AM1_tx}、i_{BM1_tx}、i_{CM1_tx}、i_{PM_tx}A, B, C three-phase current of the motor subsystem 1 and the bus current of the motor group at an effective current sampling point t_xA detected value of (x ═ 1,.., 6,1',3',5 ').

TABLE 1

According to the 9 effective current sampling points and the corresponding 18 current sampling signals in the table 1, a plurality of variables defined by the formula (4) are obtained, wherein, delta 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 group₁、t₁' the difference between the values detected at these two moments, the values of these two variables being available,. DELTA.i_{A1_t1}The real value of the phase A current of the motor set is t₁、t₁' difference between these two moments,. DELTA.i_{BM1_t3}、Δi_{PM_t3}A B-phase current sensor of the motor set and a bus current sensor of the motor group are respectively arranged at t₃、t₃' the difference between the values detected at these two moments, the values of these two variables being available,. DELTA.i_{B1_t3}The real value of the phase B current of the motor set is t₃、t₃' difference between these two moments,. DELTA.i_{CM1_t5}、Δi_{PM_t5}A C-phase current sensor of the motor set and a bus current sensor of the motor group are respectively arranged at t₅、t₅' the difference between the values detected at these two moments, the values of these two variables being available,. DELTA.i_{C1_t5}The real value of the current of the phase C of the motor set is t₅、t₅' difference of these two moments:

according to the formula (4), the proportional relation of the gain errors of the motor group I A, B, C three-phase current sensor and the motor group bus current sensor is obtained and is shown in the formula (5):

combining the formula (4) and the formula (5), a plurality of new variables are defined, as shown in the formula (6):

wherein Δ i_{AM1PM_t1}Is shown at t₁The 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 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_{BM1PM_t3}Is shown at t₃The difference value delta i of the current value measured by a current sensor of a phase B of the motor set and a current sensor of a direct current bus of the motor set under the gain error proportionality coefficient at the moment_{BM1PM_t6}Is shown at t₆The difference value delta i of the current value measured by a current sensor of a phase B of the motor set and a current sensor of a direct current bus of the motor set under the gain error proportionality coefficient at the moment_{CM1PM_t5}Is shown at t₅The difference value delta i of the current value measured by a current sensor of a C-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_{CM1PM_t2}Is shown at t₂A current sensor of a C-phase of the motor group and a current sensor of a direct current bus of the motor group measure the difference value of the current value under the gain error proportionality coefficient, and the variable values are values which can be obtained according to measured data;

by using the formula (6), the offset error between the current sensor of the motor set one A, B, C phase and the current sensor of the direct current bus of the motor group is finally obtained as shown in the formula (7):

therefore, sampling errors of all current sensors of the motor subsystem 1 and the direct current bus current sensors of the motor group can be eliminated finally.

And step 3: subsequently, the next three continuous chopping cycles of the inverter 1 of the motor subsystem 1 are adjusted to 5T_s/4, phase-shifting the inverter 1 to the home position, step ③ in FIG. 2;

and 4, step 4: finally, the subsequent chopping period of the inverter 1 of the motor subsystem 1 is adjusted to T again_sReturning the motor group system to the initial state as shown in step ④ in fig. 2;

and 5: cooperatively correcting current sampling errors of each motor subsystem of the motor group;

in the control method based on the chopping period phase shift, the chopping periods of n inverters of the system finally return to the initial state from the initial state, then the chopping periods of the inverters 2, the right angle and the n are subjected to phase shift treatment sequentially according to a similar method, the current values at relevant current sampling points are used for correcting the sampling errors of the current sensors of corresponding motor groups, finally the correlations among the multiple motor subsystems of the motor groups are used for cooperatively correcting the errors of the current sensors among the subsystems, and finally the purpose of cooperatively correcting the errors of the current sensors of the motor groups is completed.

In the motor group current sensor error collaborative correction method provided by the invention, the most critical step is how to correct the current sensor error of a single motor by using the current sampling value, and how to realize the final step of carrying out collaborative correction on the current sensor error among all subsystems by using the relevance among multiple motor subsystems of the motor group. The invention firstly takes the current sensor error correction method of the motor subsystem 1 as an example for explanation, the current sensor error correction methods of other motor subsystems are similar to those of the motor subsystem 1, and finally, how to cooperatively correct the current sensor error of the whole motor group is explained.

According to the current sampling error correction method of the motor subsystem 1, the current sampling errors of the rest n-1 motor subsystems are eliminated by combining the chopping period sequential phase shifting method provided by the invention. On the basis, the offset errors of all current sensors of the motor group can be eliminated finally, the gain error relation of all current sensors of each motor subsystem is obtained, and the gain error coefficient of the current sensors of the direct current bus of the motor group is utilized to realize the cooperative elimination of the gain error finally.