Multi-axis servo drive system

Abstract

The application discloses a multi-shaft servo driving system, comprising an AC / DC rectification module, a control module, a plurality of independent single-channel inverter sampling modules and a servo motor, wherein the AC / DC rectification module is used for converting alternating current into direct current, outputting direct current voltage DC+ and DC to each single-channel inverter sampling module, and the DC+ and DC of each single-channel inverter sampling module are connected together; the control module independently controls each single-channel inverter sampling module, samples the current of each single-channel inverter sampling module, and then controls the rotation of the servo motor. Thus, the multi-shaft servo driver of the application does not need to replace hardware when facing different power combinations, and only needs to realize any different power motor combination through motor wiring and software configuration, and simultaneously supports the change of the number of motor shafts from single shaft to any number of shafts, thereby expanding the application occasions of the multi-shaft servo driver.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of drive control, in particular to a multi-axis servo drive system. BACKGROUND

[0002] With the increasing requirements of control accuracy, processing efficiency and intelligence, the number of motor servo axes of a single processing device is required to be more and more, so multi-axis servo motor drivers appear. However, in most practical applications, the number of servo motor axes is required to be different, and each axis is also combined in different power segments, so the application range of multi-axis servo motor drivers is limited, and the flexible combination of different power segments and axis numbers cannot be solved, which brings many inconveniences to the production management of products. SUMMARY

[0003] In order to solve one or more of the above problems, the present application provides a multi-axis servo drive system capable of variable axis number and maximum current.

[0004] According to one aspect of the present application, a multi-axis servo drive system is provided, comprising an AC / DC rectifier module, a control module, a plurality of independent single-channel inverter sampling modules and a servo motor, wherein the AC / DC rectifier module is used to convert alternating current into direct current, and output direct current voltage DC+ and DC- to each single-channel inverter sampling module, and the DC+ and DC- of each single-channel inverter sampling module are connected together; the control module independently controls each single-channel inverter sampling module and samples the current of each single-channel inverter sampling module, thereby controlling the rotation of the servo motor.

[0005] In some embodiments, each single-channel inverter sampling module comprises an upper bridge single tube, a lower bridge single tube, a driving circuit of the single tube and a current sampling processing module, wherein the upper bridge single tube and the lower bridge single tube each have a control signal, and there is an intermediate output point between the upper bridge single tube and the lower bridge single tube, the current sampling processing module can output a phase current sampling output signal, the direct current voltage DC+ and DC- are connected to the upper bridge single tube and the lower bridge single tube respectively, and the intermediate output point of the upper bridge single tube and the lower bridge single tube is connected to a phase coil of the servo motor.

[0006] In some embodiments, the driving circuit comprises a bootstrap circuit.

[0007] In some embodiments, each intermediate output point can be short-circuited.

[0008] In some embodiments, the control module comprises a switching power supply, an EtherCat slave station communication module, an IO drive circuit module, an encoder communication circuit module, and a core processor module, wherein the switching power supply is used to provide power supply for the EtherCat slave station communication module, the IO drive circuit module, the encoder communication circuit module, and the core processor module, the EtherCat slave station communication is used to accept position instructions of a motion control system, the encoder communication circuit module communicates with a motor encoder and accepts a motor position signal, and the core processor module performs closed-loop calculation according to the position instructions sent by the motion control system, the motor position signal, and a current signal fed back by a single-channel inverter sampling module, thereby controlling the motor to move according to the instructions.

[0009] In some embodiments, the upper bridge single tube and / or the lower bridge single tube is an IGBT single tube.

[0010] In some embodiments, the core processor module is an xlinx Zynq7010 chip.

[0011] In some embodiments, each of the intermediate output points is short-circuited in a mode selected according to the number of servo motors.

[0012] In some embodiments, the servo motor is a three-phase motor.

[0013] In some embodiments, the number of single-channel inverter sampling modules is 3 times the number of three-phase motors.

[0014] Compared with the prior art, the present application has the following beneficial effects:

[0015] The current multi-axis servo driver needs to replace hardware modules when facing different servo motor power combinations, which limits the application of the product and increases the product hardware model. The multi-axis servo driver of the present application can realize any different power motor combination without replacing hardware when facing different power combinations, and simultaneously supports the change of the number of motor shafts from single-axis to multi-axis, which not only greatly expands the application occasions of the multi-axis servo driver, but also reduces the hardware model of the product, reduces hardware inventory, and reduces operating costs. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0017] Figure 1is a schematic diagram of the circuit connection of the three servo motors driven by the multi-axis servo drive system of the present application;

[0018] Figure 2 is a schematic diagram of the circuit structure of the single-channel inverter sampling module of the multi-axis servo drive system of the present application;

[0019] Figure 3 is a schematic diagram of the bootstrap circuit structure of the multi-axis servo drive system of the present application;

[0020] Figure 4 is a schematic diagram of the hardware structure of the control module of the multi-axis servo drive system of the present application;

[0021] Figure 5 is a control method block diagram of one embodiment of the multi-axis servo drive system of the present application for driving one servo motor; Figure 1

[0022] Figure 6 is a schematic diagram of the connection of the two servo motors driven by the multi-axis servo drive system of the present application;

[0023] Figure 7 is a control method block diagram of one embodiment of the multi-axis servo drive system of the present application for driving two servo motors; Figure 6

[0024] Figure 8 is a schematic diagram of the connection of the two servo motors driven by the multi-axis servo drive system of the present application;

[0025] Figure 9 is a current sampling processing circuit diagram of the multi-axis servo drive system of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] Referring to Figure 1 , the multi-axis servo drive system comprises an AC / DC rectifier module, a control module, a plurality of mutually independent single-channel inverter sampling modules and servo motors, wherein the AC / DC rectifier module is used to convert alternating current into direct current, output direct current voltage DC+ and - to each single-channel inverter sampling module, and the DC+ and - of each single-channel inverter sampling module are connected together.

[0028] The single-channel inverter sampling module is as shown in Figure 2 ​​As shown, each single-channel inverter sampling module includes an upper bridge single tube, a lower bridge single tube, a driving circuit of the upper bridge single tube, a driving circuit of the lower bridge single tube, and a current sampling processing circuit, wherein the upper bridge single tube and the lower bridge single tube each have a control signal a / b, and the upper bridge single tube and the lower bridge single tube have an intermediate output point c.

[0029] As shown, the current sampling processing circuit can use a chip HCPL7860, adopt 2 10-mega-ohm parallel resistors for sampling, and record an output phase current sampling output signal as d. Of course, the current sampling processing circuit can also adopt other models of chips as long as the same function is achieved, and the resistance size, quantity, and supported maximum current and the selected chip are adjusted accordingly. Figure 9

[0030] The servo controller supplies an output current to each phase of the motor, converts the current through the sampling resistor into a digital signal by using an optocoupler, and sends the signal into an FPGA for signal sampling.

[0031] The DC voltage DC+ and DC- are connected to the upper bridge single tube and the lower bridge single tube of the single-channel inverter sampling module, respectively, as shown. Figure 2 The intermediate output point of the upper bridge single tube and the lower bridge single tube is connected to a phase coil of the servo motor. Since the power supply voltage of each single-channel inverter module is the same, but the upper bridge arm driving circuit power supply is based on the voltage at point c1, and the voltage at point c1 changes with the motor control, if each inverter module is independently powered, it can also be achieved, but this will inevitably result in too many independent power supplies. To simplify the circuit, the driving circuit of each inverter sampling module includes a bootstrap circuit, so that only one power supply is needed for the entire system. As shown, VCC is the driving module power supply voltage, and c is the intermediate output point of the single tube, i.e., the motor input point. Figure 3

[0032] Since the servo motor generally uses an alternating current permanent magnet synchronous motor, which is generally a three-phase motor, each motor needs three single-channel inverter sampling modules for driving. By analogy, n motors need 3n single-channel inverter sampling modules. As shown, three servo motors need nine single-channel inverter sampling modules. For convenience of subsequent description, the three-phase coils of the servo motor are marked as u, v, and w, the motors are numbered as i, and the single-channel inverter sampling modules are numbered as j. Figure 1 In the embodiment, i = 1 ~ 3, and j = 1 ~ 9. Figure 1

[0033] Therefore, according to the wiring shown in Figure 1 , the three-phase coils of the servo motor 1 are connected to the single-channel inverter sampling modules 1, 2, and 3, respectively, the control signal of the upper bridge single tube of the single-channel inverter sampling module 1 is marked as a 11u , and the control signals of the lower bridge single tubes are marked as b​​​11u , current sampling signal is d 11u , motor coil output signal is c 11u The control signal of the upper bridge single tube of the single-channel inverter sampling module 2 is marked as a 21v , and the control signals of the lower bridge single tubes are marked as b 21v , current sampling signal is d 21v , motor coil output signal is c 21v The control signal of the upper bridge single tube of the single-channel inverter sampling module 3 is marked as a 31w , and the control signals of the lower bridge single tubes are marked as b 31w , current sampling signal is d 31w , motor coil output signal is c 31w , servo motor 1 encoder feedback signal e1.

[0034] According to the above wiring method and numbering principle, the following rules can be obtained:

[0035] The u-phase coil of the servo motor numbered i is connected to the single-channel inverter sampling module j, and the control signal of the upper bridge single tube of the single-channel inverter sampling module is marked as a jiu , and the control signals of the lower bridge single tubes are marked as b jiu , current sampling signal is d jiu , motor coil output signal is c jiu , motor encoder feedback signal e i .

[0036] Referring to Figure 4 , the aforementioned control module includes a switching power supply, an EtherCat slave station communication module, an IO drive circuit module, an encoder communication circuit module, a core processor module, and the like. The switching power supply provides power to each module circuit, the EtherCat slave station communication module receives position instructions from the motion control system, the encoder communication circuit communicates with the motor encoder and receives the motor position signal, the core processing module uses an xlinx Zynq7010 chip, which integrates an arm A9 core and an FPGA function, the FPGA module provides the ability of IO logic fast parallel processing, realizes the input and output logic processing calculation, SVPWM calculation, sampling signal calculation processing, encoder calculation processing and other function algorithms of the single-channel inverter sampling module, the arm core realizes the EtherCat communication processing, motor position, speed, torque control algorithm, and other servo motor driver application functions.

[0037] The core processing module receives the communication instructions and IO information of the motion control system, reads the motor i encoder position information e i , and the current d jiu of the single-channel inverter sampling module connected to the motor i three-phase coil uvw is sampled(j+1)iv 、d (j+2)iw , the single-channel inverter sampling module j, j+1, j+2 upper and lower bridge arm signals a jiu 、b jiu 、a (j+1)iv 、b (j+1)iv 、a (j+2)iw 、b (j+2)iw .

[0038] The motor specific control method is shown in Figure 5 , the encoder processing module processes the original encoder information ei to obtain the magnetic pole angle and feedback position posfdb_i of the motor i, and then calculates the actual speed spdfdb_i through the speed calculation;

[0039] The current sampling module j, j+1, j+2 obtains the D-axis and Q-axis actual currents Idfdb, Iqfdb of the motor i according to the motor phase currents d jiu 、d (j+1)iv 、d (j+2)iw and the magnetic pole angle of the motor, and through the clark and park algorithms.

[0040] The servo drive system receives the position command posref_i of the motor i given by the motion control system, and calculates the inverter upper and lower bridge control signals a jiu 、b jiu 、a (j+1)iv 、b (j+1)iv 、a (j+2)iw 、b (j+2)iw by using the classic position, speed and control three-ring control algorithm, so as to accurately control the movement of the motor i to the specified position.

[0041] In some embodiments, each of the intermediate output points can be short-circuited. Each of the intermediate output points is short-circuited according to the number of servo motors. Further, the control of different combinations of motor shafts is realized.

[0042] Referring to Figure 1 , which represents the wiring diagram of driving 3 servo motors.

[0043] The AC / DC rectifier module rectifies and outputs DC+ and DC- voltages, which are supplied to each single-channel sampling inverter module. All single-channel inverter sampling modules have their DC+ and DC- terminals connected together. Each single-channel inverter sampling module has an upper-bridge transistor and a lower-bridge transistor, both of which are IGBT transistors, forming the upper and lower bridge arms respectively. Each IGBT transistor supports a maximum motor output current of 15A. The rated current output depends on the heatsink design; in this implementation, the rated output current is 2.8A, and the motor output power is 400W. Each single-channel inverter sampling module connects to one phase coil of the motor; for a three-phase servo motor, three modules are connected. Therefore, nine single-channel inverter modules can connect to three servo motors.

[0044] Once each single-channel inverter sampling module is designed, its maximum output current is fixed. However, in practical applications, servo motors with different power are often used, and their phase currents are different.

[0045] refer to Figure 6 This represents the wiring diagram for driving one servo motor.

[0046] exist Figure 1 In this configuration, the intermediate output points C of the upper and lower bridges of single-channel sampling inverter modules 1, 2, and 3 are short-circuited and connected to the U-phase coil of the servo motor; the intermediate output points C of the upper and lower bridges of single-channel sampling inverter modules 4, 5, and 6 are short-circuited and connected to the V-phase coil of the servo motor; and the intermediate output points C of the upper and lower bridges of single-channel sampling inverter modules 7, 8, and 9 are short-circuited and connected to the W-phase coil of the servo motor. (Refer to...) Figure 6 , it will Figure 1 The wiring diagram for converting the aforementioned 3-axis servo driver into a single-axis servo motor driver is shown. In the diagram, the middle output points of the upper and lower bridges of the three single-channel sampling inverter modules are short-circuited and connected to one phase coil of the servo motor. This is equivalent to the single-channel sampling inverter modules being connected in parallel. Therefore, the motor phase current is equal to the sum of the sampling currents of the three single-channel sampling inverter modules. Thus, its maximum output current can be increased to a maximum of 3 times the original single-channel maximum output current, i.e., 45A, while the rated current is 10A.

[0047] Specifically, the control method for driving a single-axis servo is as follows: Figure 7 As shown. Compared to Figure 5 The servo control algorithm has an additional input / output signal port logic processing module, which implements the following functions:

[0048] 1) Determine the sub-labels and input / output signal markers of the single-channel inverter module based on the wiring of the single-channel inverter sampling module and the motor coil, as shown in the table below.

[0049]

[0050]

[0051] 2) Servo motor i phase current collection and calculation: its value is equal to the sum of the sampling current of all single-inverter sampling modules connected to the phase coil of the servo motor. As Figure 6 The servo motor u phase current is d 11u + d 21u + d 31u ; the servo motor v phase current is d 41v + d 51v + d 61v ; and the servo motor w phase current is d 71w + d 81w + d 91w .

[0052] 3) The phase current of motor i is controlled by a pair of upper and lower bridge control signals of single-inverter sampling modules, that is, the uvw three-phase coils of motor i are controlled by three pairs of independent upper and lower bridge control signals. As Figure 6 As shown in the embodiment, the servo motor u phase current is controlled by single-inverter sampling modules 1, 2, and 3, so the single-inverter sampling modules 1, 2, and 3 are set to be controlled by a pair of upper and lower bridge control signals a 1u , b 1u , that is, the upper bridge control signals a 11u , a 21u , a 31u are shorted to a 1u , and the lower bridge control signals b 11u , b 21u , b 31u are shorted to b 1u ; similarly, the servo motor v phase current is controlled by single-inverter sampling modules 4, 5, and 6, and the pair of upper and lower bridge control signals of the v phase are a 1v , b 1v , that is, the upper bridge control signals a 41v , a 51v , a 61v are shorted to a 1v , and the lower bridge control signals b 41v , b 51v , b 61v are shorted to b 1v ; the servo motor w phase current is controlled by single-inverter sampling modules 7, 8, and 9, and the pair of upper and lower bridge control signals of the w phase are a 1w , b 1w , that is, the upper bridge control signals a 71w , a 81w , a 91w are shorted to a 1w , and the lower bridge control signals b 71w , b 81w , b 91w are shorted to b 1w.

[0053] Through the above input and output signal port processing module setting, a three-axis servo motor driver becomes a single-axis servo driver with 3 times the original maximum output current. That is, a single-axis servo driver with a maximum output current of 45A and a rated output current of 10A.

[0054] The system can also short-circuit any two single-channel inverter sampling modules to become a two-axis motor servo driver. For example, short-circuit the middle output points c of the upper and lower bridges of single-channel sampling inverter modules 1 and 2 to the u-phase coil of servo motor 1, short-circuit the middle output points c of the upper and lower bridges of single-channel sampling inverter modules 3 and 4 to the v-phase coil of servo motor 1, and short-circuit the middle output points c of the upper and lower bridges of single-channel sampling inverter modules 5 and 6 to the w-phase coil of servo motor 1. Single-channel sampling inverter modules 7, 8, and 9 are connected to the uvw three-phase coils of servo motor 2, respectively. Figure 8 , which will Figure 1 The aforementioned 3-axis servo driver becomes a 2-axis servo motor driver wiring diagram. In the diagram, each phase coil of servo motor 1 is short-circuited and connected together by the middle output points of the upper and lower bridges of two single-channel sampling inverter modules, which is equivalent to two single-channel sampling inverter modules in parallel. Therefore, the phase current of motor 1 is equal to the sum of the sampling currents of two single-channel sampling inverter modules, and therefore its maximum output current can be maximally increased to twice the original single-channel maximum output current, i.e. 30A, with a rated current of 6.8A. The maximum output of the phase current of motor 2 is the maximum output current of the single-channel inverter, i.e. 15A.

[0055] The control method is similar to the aforementioned control method, according to Figure 8 the wiring, the input and output signal port logic processing module is processed as follows:

[0056] 1) The u-phase current of servo motor 1 is d 11u +d 21u ; the v-phase current of servo motor is d 31v +d 41v ; the w-phase current of servo motor is d 51w +d 61w ; and the uvw-phase current of servo motor 2 is d 72u , d 82v , d 92w ;

[0057] 2) The u-phase current of servo motor 1 is controlled by single-channel inverter sampling modules 1 and 2, so single-channel inverter sampling modules 1 and 2 are set to a pair of upper and lower bridge control signals a 1u , b 1u control, i.e. the upper bridge control signals a 11u , a 21u of each inverter are short-circuited to a 1u, lower bridge control signal b 11u , b 21u short b 1u ; similarly, the v-phase current of the servo motor is controlled by the single-inverter sampling module 3, 4, and a pair of upper and lower bridge control signals of the v-phase are a 1v , b 1v , that is, the upper bridge control signal a 31v , a 41v of each inverter is shorted to a 1v , and the lower bridge control signal b 31v , b 41v is shorted to b 1v ; the w-phase current of the servo motor is controlled by the single-inverter sampling module 5, 6, and a pair of upper and lower bridge control signals of the w-phase are a 1w , b 1w , that is, the upper bridge control signal a 51w , a 61w of each inverter is shorted to a 1w , and the lower bridge control signal b 51w , b 61w is shorted to b 1w .

[0058] 3) The uvw-phase current of the servo motor 2 is controlled by the single-inverter sampling module 7, 8, 9, and the upper and lower bridge control signals are a 72u , b 72u , a 82v , b 82v , a 92w , b 92w .

[0059] Through the above-mentioned any combination, the multi-axis servo driver of the present application does not need to replace the hardware when facing different power combinations, and only needs to realize any different power motor combination by motor wiring and software configuration, and at the same time supports the change of the number of motor shafts from single-axis to any number of shafts, not only greatly expands the application occasions of the multi-axis servo driver, but also reduces the hardware models of the product, reduces the hardware inventory, and reduces the operating cost.

Claims

1. A multi-axis servo drive system, characterized by, The application relates to a multi-axis servo driving system, which comprises an AC / DC rectifier module, a control module, a plurality of independent single-channel inverter sampling modules and a servo motor. The AC / DC rectifier module is used for converting alternating current into direct current and outputting direct current voltage DC+ and DC- to each single-channel inverter sampling module; the DC+ and DC- of each single-channel inverter sampling module are connected together. The control module independently controls each single-channel inverter sampling module and samples the current of each single-channel inverter sampling module, thereby controlling the rotation of the servo motor. Each single-channel inverter sampling module comprises an upper bridge single tube, a lower bridge single tube, a driving circuit of the upper bridge single tube and a driving circuit of the lower bridge single tube; the upper bridge single tube and the lower bridge single tube have one control signal respectively; the upper bridge single tube and the lower bridge single tube have an intermediate output point; each intermediate output point can be short-circuited; and each intermediate output point is selected according to the number of the servo motor. The control module comprises an encoder communication circuit module and a core processor module; the encoder communication circuit module communicates with the motor encoder and receives the motor position signal; the core processor module reads the motor encoder position information, carries out closed-loop calculation according to the position instruction, the motor position signal and the current signal fed back by the single-channel inverter sampling module, and controls the motor to move according to the instruction. The encoder processing module processes the original information of the encoder to obtain the magnetic pole angle and the feedback position of the motor, and obtains the actual speed through speed calculation; the current sampling module calculates the D-axis and Q-axis actual currents of the motor according to the motor phase current and the motor magnetic pole angle; and the control signal of the single-channel inverter sampling module is calculated according to the known motor position instruction.

2. The multi-axis servo driving system according to claim 1, wherein each single-channel inverter sampling module comprises an upper bridge single tube, a lower bridge single tube, a driving circuit of the single tube and a current sampling processing module. The current sampling processing module can output a phase current sampling output signal. The direct current voltage DC+ and DC- are connected to the upper bridge single tube and the lower bridge single tube respectively. The intermediate output point of the upper bridge single tube and the lower bridge single tube is connected to a phase coil of the servo motor.

3. The multi-axis servo driving system according to claim 2, wherein the driving circuit comprises a bootstrap circuit.

4. The multi-axis servo driving system according to claim 1, wherein the control module further comprises a switching power supply, an EtherCat slave communication module and an IO driving circuit module. The switching power supply is used for providing power supply for the EtherCat slave communication module, the IO driving circuit module, the encoder communication circuit module and the core processor module. The EtherCat slave communication module is used for receiving a position instruction. The upper bridge single tube and / or the lower bridge single tube is an IGBT single tube. The core processor module is an xlinx Zynq7010 chip. The servo motor is a three-phase motor. The number of the single-channel inverter sampling modules is three times the number of the three-phase motor.

5. The multi-axis servo drive system of claim 2, wherein, ​ 6. The multi-axis servo drive system of claim 4, wherein, ​ 7. The multi-axis servo drive system of any of claims 1-6, wherein, ​ 8. The multi-axis servo drive system of claim 7, wherein, ​

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