A power supply switching method applied to a stator segment power supply topology of a segmented long primary linear motor

Abstract

The application provides a stator segment power supply topology and a power supply switching algorithm applied to a segmented long primary linear motor, a frequency converter power supply supplies power to motor stator segments through a switching switch, the switching switch is composed of bidirectional thyristors and is connected in parallel to two adjacent stator segments of the same frequency converter, the two adjacent stator segments are connected to the frequency converter in different phase sequences, during the stator segment power supply switching process, the frequency converter power supply supplies power to the stator segment to be turned off and the stator segment to be turned on at the same time, the electric angle of the dq axis synchronous rotating coordinate system of the motor controller remains unchanged, and the amplitude of the current reference value of the current loop of the motor controller changes with the electric angle of the dq axis synchronous rotating coordinate system of the motor, the stator segment power supply topology and the power supply switching algorithm can increase the current of the stator segment to be turned on while reducing the current of the stator segment to be turned off, shorten the power supply switching time and inhibit the current impact of the motor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electric machines and electric machine control technology, and particularly relates to a stator segment power supply topology and power supply switching method applied to a segmented long primary linear motor. BACKGROUND

[0002] For the purpose of improving the efficiency of the electric machine and reducing the capacity of the inverter, the long primary linear motor usually adopts the segmented power supply mode, and only the stator segment near the mover plate is powered. With the movement of the mover plate, the stator segments in the forward direction of the mover plate are sequentially powered on, while the stator segments far from the mover plate are sequentially powered off. The switching of the switching switch in the process of the stator segment switching in and out will cause transient current surges, affecting the smooth operation of the electric machine, and the duration of the switching process will limit the maximum operating speed of the linear motor. The existing winding switching technology is mainly divided into short-circuit freewheeling switching, synchronous zero-crossing switching and phase-by-phase zero-crossing switching.

[0003] The short-circuit freewheeling switching method proposed by Cui Mingkai in the literature "Variable Parameter PI Control based on Fuzzy Logic Strategy for Dual-Winding PMSM" first short-circuits the winding before switching the winding, realizing winding series-short-circuit-parallel and parallel-short-circuit-series switching. When the winding is short-circuited, the inverter switch tube is fully turned off to avoid inverter short-circuit, and the current does not need to be reduced to 0 during the switching process. This method has no surge voltage, but this method is only suitable for the occasion where the current connected with the winding does not change before and after the switching of the switch, and is not suitable for linear motors.

[0004] The synchronous zero-crossing switching method proposed by Seong-Hwan Im et al. in the literature "A Snubberless Solid-State Tap Changer for Permanent Magnet Synchronous Motors" requires the center and end taps of the winding to be connected together through IGBT, and the phase current is turned off at zero through the IGBT freewheeling diode. Benefiting from the special winding form, the inverter output voltage can be used to reduce the current of the winding to be turned off, but this method can only switch at a specific current phase angle, and needs to install a tap switch.

[0005] The phase-by-phase zero-crossing switching method proposed by Raymond B Sepe in the patent "Block switching transient minimization for linear motors and inductive loads" changes the phase winding structure when the phase current crosses zero, which requires a current measurement circuit to detect the current zero-crossing point. This method has the disadvantages of winding imbalance during commutation and switching time of at least half of the electrical period, and the switching time is limited. SUMMARY

[0006] To solve the above technical problems, the present application provides a stator segment power supply topology and power supply switching method applied to a segmented long primary linear motor, which meets the speed, thrust and other control performance of high-speed linear motors.

[0007] To achieve the above purpose, the technical scheme adopted by the present application is:

[0008] A stator segment power supply topology and power supply switching method applied to a segmented long primary linear motor, the linear motor segmented power supply topology comprising a motor controller, a frequency converter power supply, a switching switch, and motor stator segments, the frequency converter power supply supplying power to the motor stator segments through the switching switch, the switching switch being composed of bidirectional thyristors and connected in parallel to the same frequency converter, the adjacent two stator segments connected to the frequency converter in different phase sequences, the motor controller issuing instructions to supply power to or cut off the power supply of the motor stator segments according to the detected mover position signal;

[0009] During the stator segment power supply switching process, the frequency converter power supply simultaneously supplies power to the stator segments to be turned off and the stator segments to be turned on, the electric angle of the motor controller dq-axis synchronous rotating coordinate system remains unchanged, and the amplitude of the current reference value of the motor controller current loop current changes with the electric angle of the motor dq-axis synchronous rotating coordinate system.

[0010] Further, the method comprises the following steps:

[0011] Step 1: In the linear motor segmented power supply topology, the stator segments connected in parallel to the same frequency converter satisfy the following rules: among all the stator segments connected in parallel to the same frequency converter, the phase sequences of any two adjacent stator segments connected to the frequency converter are different; the connection phase sequence makes the phase difference between the stator segment αβ-axis stationary coordinate system and the frequency converter αβ-axis stationary coordinate system on the positive direction side of the track, i.e. the counterclockwise direction of the motor αβ-axis stationary coordinate system, larger than the phase difference on the negative direction side of the track.

[0012] Step 2: During the switching process, the motor controller keeps the electric angle of the dq-axis synchronous rotating coordinate system unchanged. ​The stator segment power supply switching instruction is sent out at this moment, requiring to close the switching switch of the frequency converter and the current mth stator segment, and to turn on the switching switch of the frequency converter power supply and the m+1th stator segment The motor dq-axis synchronous rotating coordinate system electric angle, i.e. the electric angle between the motor dq-axis synchronous rotating coordinate system and the motor αβ-axis static coordinate system is recorded as The control signal of the mth stator segment switching switch is changed from 1 to 0, i.e. from turn-on to turn-off The control signal of the m+1th stator segment switching switch is changed from 0 to 1, i.e. from turn-off to turn-on The stator segment power supply switching flag bit is changed from 0 to 1 ;

[0013] Step 3, the motor static coordinate system axis and the frequency converter static coordinate system phase deviation ; during the stator segment power supply switching process, the phase deviation is equal to the phase deviation between the static coordinate system axis of the stator segment to be turned off and the frequency converter static coordinate system axis

[0014] Step 4, the motor controller dq-axis synchronous rotating coordinate system electric angle, i.e. the electric angle between the motor controller dq-axis synchronous rotating coordinate system and the frequency converter αβ static coordinate system , the motor controller dq-axis current reference value , , the motor controller dq-axis current measurement value , , is calculated according to the following formula:

[0015] (1)

[0016] (2)

[0017] (3)

[0018] In the above formula, v is the moving speed of the mover plate; sign is the sign function; the mover plate moves in the positive direction of the orbit as “+” and vice versa as “-”, and the positive direction of the orbit is the counterclockwise direction of the motor αβ-axis static coordinate system and are the expected motor dq-axis currents , and are the measurement values of the frequency converter three-phase output currents is the electric angle between the motor dq-axis synchronous rotating coordinate system and the motor αβ-axis static coordinate system Park transformation matrix; is a Clark transformation matrix;

[0019]

[0020] ;

[0021] Step 5; motor controller current loop calculates motor controller dq axis reference voltage , and , motor controller dq axis reference voltage and ; calculates reference value of frequency converter A, B, C three-phase voltage with inverse matrix of Park coordinate transformation and pseudo-inverse matrix of Clark coordinate transformation , and ;

[0022] (4)

[0023] Step 6, motor dq axis synchronous rotating coordinate system electric angle when the following formula is met, the stator segment power supply switching is completed, flag bit is cleared;

[0024] (5).

[0025] Further, among all the stator segments connected to the same frequency converter, any two adjacent stator segments have different phase sequence connected to the frequency converter; the connection phase sequence makes the phase difference between the stator segment αβ axis stationary coordinate system and the frequency converter αβ axis stationary coordinate system on the positive direction side of the track, i.e. the counterclockwise direction of the motor αβ axis stationary coordinate system, larger than the phase difference on the negative direction side of the track .

[0026] Further, during the stator segment power supply switching process of the segmented linear motor, the electric angle of the motor controller dq axis synchronous rotating coordinate system, the motor controller dq axis current reference value and the motor controller dq axis current measurement value are calculated according to formulas (1), (2) and (3).

[0027] Further, during the stator segment power supply switching process of the segmented linear motor, the electric angle of the motor controller dq axis synchronous rotating coordinate system when formula (5) is met, the stator segment power supply switching is completed.

[0028] Advantages:

[0029] The application has the advantages of small hardware change and low change difficulty, and can be rapidly applied to existing segmented linear motor application occasions; the application has the advantage of short power supply switching time, and can weaken the limitation of power supply switching time on the running speed of the linear motor. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a power supply topology diagram of a three-phase segmented long primary linear induction motor powered by double frequency converters, in the diagram, the segmented linear motor has 7 stator segments, among which the mth, m+1th, m+2th and m+3th stator segments are connected to the first frequency converter through switching switches, and the pth, p+1th and p+2th stator segments are connected to the second frequency converter.

[0031] Figure 2 is a variation waveform of the control instruction of the switching switch of the mth, pth and m+1th stator segments with the position of the moving plate, the position of the moving plate is within the dotted line, the stator segment power supply switching can be performed.

[0032] Figure 3 is a variation waveform of the control instruction of the switching switch of the mth, pth and m+1th stator segments with the position of the moving plate when the moving plate moves forward.

[0033] Figure 4 is a variation curve of the three-phase current of the stator segment during the power supply switching process of the mth to m+1th stator segment when the application is performed.

[0034] Figure 5 is a variation curve of the three-phase current of the stator segment during the power supply switching process of the mth to m+1th stator segment when the traditional phase-by-phase zero-crossing switching method is performed. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the application clearer and more understandable, the application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application. In addition, the technical features involved in each embodiment of the application described below can be combined with each other as long as they do not conflict with each other.

[0036] In the process of powering the parallel segmented linear motor stator segments by multiple frequency converters, the frequency converter only powers the stator segments near the moving plate. The power supply topology of the segmented linear motor is shown in Figure 1 , in the diagram, the mth, m+1th, m+2th and m+3th stator segments are connected to the first frequency converter through switching switches, and the pth, p+1th and p+2th stator segments are connected to the second frequency converter. The variation curve of the switching control signal of the mth, pth and m+1th stator segments #m, #p, #m+1 with the movement of the moving plate is shown in Figure 2 . Table 1 is Figure 1The phase difference between the stator segment αβ stationary coordinate system and the first frequency converter αβ stationary coordinate system in the shown topology:

[0037] Table 1

[0038]

[0039] The moving speed of the mover plate When the position of the mover plate satisfies the following formula, the first frequency converter can perform power supply switching of the mth and (m+1)th stator segments #m-#m+1.

[0040] (1)

[0041] In the formula, is the length of the stator segment, is the length of the mover plate, is the distance of the mover plate from the mth stator segment #m, and when the mover plate moves in the positive direction of the track >0, and otherwise <0; the positive direction of the track is the counterclockwise direction of the motor αβ stationary coordinate system.

[0042] When the frequency converter supplies power to the mth stator segment alone, the dq-axis synchronous rotating coordinate system electric angle of the motor controller is as follows:

[0043] (2)

[0044] In the formula, is the dq-axis synchronous rotating coordinate system electric angle of the motor controller, i.e., the electric angle between the dq-axis synchronous rotating coordinate system of the motor controller and the αβ stationary coordinate system of the frequency converter, is the dq-axis synchronous rotating coordinate system electric angle of the motor, i.e., the electric angle between the dq-axis synchronous rotating coordinate system of the motor and the αβ stationary coordinate system of the motor, is the phase difference between the αβ stationary coordinate system of the mth stator segment and the αβ stationary coordinate system of the first frequency converter.

[0045] It is determined by the connection sequence of the stator segment and the frequency converter. If the three-phase output terminals "A, B, C" of the frequency converter are connected to the three-phase windings "a, b, c" of the mth stator segment in the manner of "A-a, B-b, C-c", then ; if connected in the manner of "A-c, B-a, C-b", then ; and if connected in the manner of "A-b, B-c, C-a", then .

[0046] The electric angle has a period of , and the phase difference is equivalent to .

[0047] The frequency converter switches from supplying power to the mth stator segment to supplying power to the m+1th stator segment As follows:

[0048] (3)

[0049] wherein is the time of starting of the power supply switching, is is the electrical angle of the motor dq-axis synchronous rotating coordinate system and the motor αβ stationary coordinate system at the time, is the moving speed of the mover plate during the switching process.

[0050] When the following condition is met, the switching process ends:

[0051] (4)

[0052] wherein sign is a sign function.

[0053] During the operation, the dq-axis current measurement value of the motor controller is calculated in the following manner:

[0054] (5)

[0055] wherein and are the dq-axis current measurement value of the motor controller, , and are the three-phase current of the frequency converter measured by the frequency converter.

[0056] and are the Clark coordinate transformation matrix and the Park coordinate transformation matrix, and the formulas are as follows:

[0057] (6)

[0058] During the power supply switching process of the stator segment, the dq-axis current reference value of the motor controller is determined by the expected motor dq-axis current, the motor dq-axis synchronous rotating coordinate system electrical angle and the moving speed of the mover plate, and is calculated in the following manner:

[0059] (7)

[0060] wherein and are the dq-axis current reference value of the motor controller, and sign is a sign function, and is the desired motor dq-axis current, v is the mover plate moving speed, sign is the sign function, "+" for the mover moving in the positive direction of the track, "-" for the opposite, the positive direction of the track is the counterclockwise direction of the motor αβ-axis stationary coordinate system.

[0061] Outside the stator segment power switching process, the motor controller dq-axis current reference value is equal to the desired motor dq-axis current, the calculation formula is as follows:

[0062] (8)

[0063] In the working process, the phase voltage reference value of the frequency converter is calculated as follows:

[0064] (9)

[0065] In the formula and is the motor controller dq-axis reference voltage, which is calculated by the motor controller current loop according to , and , ; is the inverse matrix of , is the pseudo-inverse matrix of , the value is as follows:

[0066] (10)

[0067] As shown in Figure 3 , taking the stator segment switching process of the first frequency converter of the three-phase segmented long primary linear induction motor moving forward as an example, the power supply topology diagram is shown in Figure 1 , there are 7 stator segments in the figure, the mth, m+1th, m+2th, m+3th stator segments are connected to the first frequency converter through the switching switch, and the pth, p+1th, p+2th stator segments are connected to the second frequency converter through the switching switch.

[0068] Step 1, , the motor controller obtains the desired motor dq-axis current and from the existing speed loop of the motor controller or the host computer, obtains the slip frequency from the host computer, measures the three-phase current , and from the current sensor installed on the frequency converter, obtains the mover plate position and the mover plate speed from the position sensor, calculates the electrical angle of the motor dq-axis synchronous rotating coordinate system , is the sampling interval time;

[0069] (11)

[0070] wherein is the pole pitch of the electric machine.

[0071] Step 2, according to the mover plate position calculate the control instruction of all switching switches connected by the first frequency converter at the moment :

[0072] (12)

[0073] Step 3, if there is , make and , continue to execute, otherwise jump to step 5;

[0074] Step 4, let , ;

[0075] Step 5, calculate the phase deviation of the stator segment and the first frequency converter , , , and The numerical value is shown in Table 1:

[0076] (13)

[0077] Step 6, if , continue to execute, otherwise jump to step 8;

[0078] Step 7, calculate the electric machine controller dq axis synchronous rotating coordinate system electric angle , the electric machine controller dq axis synchronous rotating coordinate system current reference value and , calculate the electric machine controller dq axis synchronous rotating coordinate system current measurement value and , jump to step 9;

[0079] (14)

[0080] Step 8, calculate the electric machine controller dq axis synchronous rotating coordinate system electric angle outside the stator segment power supply switching process, calculate the electric machine controller dq axis current reference value and , calculate the electric machine controller dq axis current measurement value and​ ;

[0081] (15)

[0082] Step 9, the motor controller current loop calculates the motor controller dq axis reference voltage , , and ; and ;

[0083] Step 10, the motor controller calculates the first frequency converter A, B, C three-phase voltage reference value with , the inverse matrix of Park coordinate transformation and the pseudo-inverse matrix of Clark coordinate transformation , and ;

[0084] (16)

[0085] Step 11, if and , then ;

[0086] Step 12, output , , to the first frequency converter.

[0087] Figure 4 is the change curve of the three-phase current of the stator segment during the power supply switching process of the mth to the m+1th stator segment when the motor stator segment power supply topology and power supply switching method proposed by the present application are executed, the current frequency is 40 Hz, and the power supply switching time is 3.7 milliseconds. Among them, Ia_m, Ib_m, Ic_m are the A, B, C three-phase currents of the mth stator segment, and Ia_m+1, Ib_m+1, Ic_m+1 are the A, B, C three-phase currents of the m+1th stator segment.

[0088] Figure 5 is the change curve of the three-phase current of the stator segment during the power supply switching process of the mth to the m+1th stator segment when the traditional phase-by-phase zero-crossing switching method is executed. The current frequency is 40 Hz, and the power supply switching time is 10.2 milliseconds. In the figure, Ia_m, Ib_m, Ic_m are the A, B, C three-phase currents of the mth stator segment, and Ia_m+1, Ib_m+1, Ic_m+1 are the A, B, C three-phase currents of the m+1th stator segment.

[0089] In summary, the switching process of the segmented long primary linear motor stator segment power supply method of the present application takes less time, and the switching time under the same working condition is 37% of the traditional method.

[0090] While the foregoing detailed description of the application has been described with particularity, it should be readily apparent to those having ordinary skill in this art that various changes can be made without deviating from the spirit and scope of the application, which is defined by the appended claims.

Claims

1. A power supply switching method applied to a power supply topology of a stator segment of a segmented long primary linear motor, characterized in that: The linear motor segmented power supply topology comprises a motor controller, a frequency converter power supply, a switching switch, and motor stator segments; the frequency converter power supply supplies power to the motor stator segments through the switching switch; the switching switch is composed of bidirectional thyristors and is connected in parallel to the same frequency converter; adjacent two stator segments are connected to the frequency converter in different phase sequences; the motor controller sends instructions for supplying power to or cutting off power supply to the motor stator segments according to the detected mover position signal; During the stator segment power supply switching process, the frequency converter power supply simultaneously supplies power to the stator segments to be cut off and the stator segments to be turned on; the electric angle of the motor controller dq-axis synchronous rotating coordinate system remains unchanged; and the amplitude of the motor controller current loop current reference value changes with the electric angle of the motor dq-axis synchronous rotating coordinate system.

2. Power supply switching method for a stator segment power supply topology of a segmented long primary linear motor according to claim 1, characterized in that, The method comprises the following steps: Step 1, in the linear motor segmented power supply topology, the stator segments connected to the same frequency converter satisfy the following rules: among all the stator segments connected to the same frequency converter, any two adjacent stator segments are connected to different phase sequences of the frequency converter; the connection phase sequence makes the phase difference between the stator segment αβ stationary coordinate system on the positive direction side of the track, i.e. the counterclockwise direction of the motor αβ stationary coordinate system, and the frequency converter αβ stationary coordinate system larger than the phase difference between the stator segment αβ stationary coordinate system on the negative direction side of the track and the frequency converter αβ stationary coordinate system ​ Step 2, in the switching process, the motor controller sends stator segment power supply switching instruction at time, requiring to close the switching switch of the frequency converter and the current powered mth stator segment, and to turn on the switching switch of the frequency converter power supply and the m+1th stator segment , the motor dq axis synchronous rotating coordinate system electrical angle at this time, i.e. the electrical angle between the motor dq axis synchronous rotating coordinate system and the motor αβ axis stationary coordinate system , recorded as , the control signal of the mth stator segment switching switch is changed from 1 to 0, i.e. from on to off, and the control signal of the m+1th stator segment switching switch is changed from 0 to 1, and the stator segment power supply switching flag bit is enabled ; Step 3, calculating the motor stationary frame axis and the inverter stationary frame phase deviation of the axis phase deviation during the stator segment power supply switching process is equal to the stationary frame of the stator segment to be switched off axis and the inverter stationary frame phase deviation of the axis Step 4, the electrical angle between the motor controller dq-axis synchronous rotating coordinate system and the frequency converter αβ stationary coordinate system , motor controller dq-axis current reference value 、 , motor controller dq-axis current measurement value 、 , calculated according to the following formula: （1） （2） （3） In the above formula, v is the moving speed of the mover plate; sign is a sign function; the mover plate moves in the positive direction of the track as "+", and in the negative direction as "-"; the positive direction of the track is the counterclockwise direction of the motor αβ axis stationary coordinate system; and is the desired motor dq axis current; 、 and is the measured value of the three-phase output current of the frequency converter; is the electrical angle between the motor dq axis synchronous rotating coordinate system and the motor αβ axis stationary coordinate system, is the Park transformation matrix; is the Clark transformation matrix; ； Step 5; Motor controller current loop according to , and , Calculate motor controller dq-axis reference voltage and ; Calculate reference values for frequency converter A, B, C three-phase voltage with inverse matrix of Park coordinate transformation and pseudo-inverse matrix of Clark coordinate transformation , and ; （4） Step 6, the electric angle of the motor dq axis synchronous rotating coordinate system The stator section power supply switching is completed when the following formula is met, Flag bit is cleared; （5）。 3. The power supply switching method for the power supply topology of the stator segment of the segmented long primary linear motor according to claim 2, characterized in that: All the stator segments connected to the same frequency converter in parallel, any two adjacent stator segments connected to the frequency converter have different phase sequence; the connection phase sequence makes the phase difference between the stator segment αβ stationary coordinate system and the frequency converter αβ stationary coordinate system on the positive direction side of the track, i.e. the counterclockwise direction of the motor αβ stationary coordinate system, larger than the phase difference on the negative direction side of the track .

4. The power supply switching method for the power supply topology of the stator segment of the segmented long primary linear motor according to claim 2, characterized in that: During the stator segment power supply switching process of the segmented linear motor, the electric angle of the motor controller dq-axis synchronous rotating coordinate system, the motor controller dq-axis current reference value, and the motor controller dq-axis current measurement value are calculated according to Formulas (1), (2), and (3).

5. The power supply switching method for the power supply topology of the stator segment of the segmented long primary linear motor according to claim 2, characterized in that: The motor dq axis synchronous rotation coordinate system electric angle in the process of segment linear motor stator segment power supply switching The stator segment power supply switching ends when formula (5) is met.

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