Manufacturing method of dual-drive vector controller for brushless DC motor

Abstract

The present invention relates to the technical field of motor controllers, and discloses a method for making a dual-drive vector controller for a brushless DC motor, including the following specific steps: calculation of the back-electromotive force characteristics of a brushless DC motor. When the motor is running, only two phases are turned on at the same time. Since the rotor magnetic induction intensity is a trapezoidal distribution, the zero-crossing point can be obtained by measuring the back-electromotive force of the non-conducting phase, and the position information of the rotor can be estimated accordingly; controller hardware design, which mainly consists of two parts, wherein the control and speed regulation module realizes speed regulation and commutation logic control through a control circuit; controller software control strategy; dual-drive coordination strategy; dual-drive vector controller design. The dual-drive vector controller designed by calculating the back-electromotive force characteristics of a brushless DC motor, controller hardware design, controller software control strategy, dual-drive coordination strategy and dual-drive vector controller can realize synchronous control of multiple motors, thereby achieving the effect of load balance and reasonable distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of motor controllers, and in particular to a method for manufacturing a brushless DC motor dual-drive vector controller. Background Art

[0002] Brushless DC motor (BLDC), also known as electronically commutated motor (ECM or EC motor) or synchronous DC motor, is a synchronous motor that uses a direct current (DC) power supply. In essence, a brushless DC motor uses a DC power input and uses an inverter to convert it into a three-phase AC power supply with position feedback. There are various types of motors, and the brushless DC motor is the most ideal speed-regulating motor today. It combines the advantages of DC motors and AC motors. It has both the good adjustment performance of DC motors and the advantages of AC motors such as simple structure, no commutation sparks, reliable operation and easy maintenance. Therefore, it is very popular in the market and is widely used in automobiles, home appliances, industrial equipment and other fields.

[0003] However, in some applications that require complex motion control, such as industrial robots and CNC machine tools, simple control methods may not be able to meet the requirements of brushless DC motors that lack a dual-drive vector controller, resulting in limited system functions and inability to achieve synchronous control of multiple motors. Therefore, a method for making a dual-drive vector controller for a brushless DC motor is proposed. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for manufacturing a dual-drive vector controller for a brushless DC motor, which solves the problem that a brushless DC motor lacking a dual-drive vector controller cannot achieve synchronous control of multiple motors.

[0005] To achieve the above objectives, the present invention is implemented by the following technical solutions: A method for manufacturing a brushless DC motor dual-drive vector controller comprises the following specific steps:

[0006] Step 1: Calculation of the back-EMF characteristics of the brushless DC motor. When the motor is running, only two phases are turned on at the same time. Since the rotor magnetic induction intensity is a trapezoidal distribution, the zero-crossing point can be obtained by measuring the back-EMF of the non-conducting phase, and the rotor position information can be estimated accordingly.

[0007] Step 2: Controller hardware design. The overall control of the brushless DC motor is mainly composed of two parts. The control and speed regulation module realizes speed regulation and commutation logic control through the control circuit, and drives the motor through the drive circuit; the position detection module mainly estimates the rotor position by obtaining the back electromotive force zero-crossing signal, and feeds it back to the control circuit to calculate the speed and update the commutation logic state;

[0008] Step 3: Controller software control strategy. The controller software system mainly includes initialization, interrupt service program and subroutine. When the system starts, the initialization part will initialize and assign values ​​to the control system interface, timer, state variables and other parameters. After the initialization is completed, the program enters the main loop, automatically jumps according to the input signal state machine, calls the subroutine and waits for interruption. The interrupt part realizes important functions such as current sampling, communication, commutation, PWM interruption, etc. The subroutine part mainly realizes the start-up and operation logic control of the motor;

[0009] Step 4: Dual-drive collaborative strategy. Taking the stamping machine as an example, when the transmission process produces a periodic characteristic moment of inertia and there is load interference, it will cause speed and displacement deviations in the operation stage of the stamping machine, which makes the motion state in each cycle different from the motion target originally designed. This deviation may cause interference between the dual motors. When adjusting the above deviations, an adaptive sliding mode controller can be established, and the position and speed deviations can be dynamically controlled according to the feedback of the position and speed sensors to ensure that the dual motor drive stage forms a coordinated and synchronized state;

[0010] Step 5: Design of dual-drive vector controller. The servo motor in the stamping machine has a large inherent torque. At this time, there is no need to consider the friction torque caused by viscous damping. In order to improve the applicability of the system, a disturbance function with normal distribution characteristics is constructed.

[0011] Preferably, in step one, taking the process of an electrical angle of 30° to 90° as an example, the high-voltage side MOSFET "V1" is in a PWM (Pulse Width Modulation) state, and the low-voltage side MOSFET "V6" is in an on state, which is an H_PWM-L_ON conduction mode. The current flows into the motor phase A and flows out of the motor phase B. At this time, the A-phase winding and the B-phase winding are turned on, and the C-phase is suspended. During the operation of the motor, the rotation of the rotor will cause each phase winding to generate an induced back electromotive force. When the electrical angle is 60°, the back electromotive force of the C-phase winding passes through the zero point. Since there is a phase difference of 30° electrical angle between the ideal commutation point and the previous back electromotive force zero point, a 30° electrical angle delayed commutation method is required, that is, commutation is performed at 90°.

[0012] Preferably, in step 1, ideally, the phase voltage can be obtained by the difference between the neutral point voltage and the terminal voltage, and the actual neutral point of the winding in the motor model. Taking phase C as an example, the winding voltage equation is explained. When phases A and B are conducting, phase C is not conducting. At this time, the phase voltage of phase C can be expressed as: EC = Uc-Un, where: EC is the back electromotive force of phase C; UC is the voltage between point C and ground; Un is the voltage between point n and ground.

[0013] Preferably, in step one, the neutral point is generally not connected separately during motor manufacturing, but is hidden in the stator winding, and the voltage between the neutral point and the ground cannot be directly measured. In order to measure the back electromotive force, three resistors with equal resistance are connected at points A, B, and C to form a star network, and a virtual neutral point m is introduced, thereby obtaining: EC=Uc-Um, where: Um is the voltage between the virtual neutral point m and the ground.

[0014] Preferably, in step 2, the control and speed regulation module selects a 16-bit high-performance digital signal controller dsPIC30F series chip dedicated to motor control as the main control chip, and adopts a three-phase full-bridge inverter circuit to drive the motor. In the inverter circuit, the high-voltage side MOSFET adopts a PWM mode, and the low-voltage side MOSFET adopts a constant-on mode (H_PWM-L_ON mode). Since the PWM signal directly output by the dsPIC30F has a low voltage and low power, and its driving capability is insufficient, it cannot directly drive a brushless DC motor. Therefore, it is necessary to build an additional drive circuit in the peripheral circuit to increase the driving power of the PWM signal. The drive circuit is built using an IR2103 drive chip. In addition, a bootstrap circuit can be set around the IR2103 to provide a bootstrap floating power supply. In this way, only one power supply is needed to drive 6 MOSFETs through 3 IR2103s, thereby simplifying the drive circuit and saving power.

[0015] Preferably, in step three, in order to quickly and accurately increase the speed to the rated speed, the motor adopts a three-stage starting method, which mainly includes the following processes: a pre-positioning stage, an open-loop speed-up stage, and a closed-loop speed-up stage.

[0016] Preferably, in step five, when the system is jittering, it will not be able to reach a stable operating control state, and the gain K(t) of the sliding mode variable structure is compensated by fuzzy control, thereby achieving an adaptive effect. To ensure that the system can quickly reach the sliding surface after being disturbed, the following input and output fuzzy sets are established for the system: F = {NB, NM, NS, ZO, PS, PM, PB}, where: NB, NM, NS are respectively negative large, negative medium, and negative small; ZO is zero; PS, PM, PB are respectively positive small, positive medium, and positive large, and the following fuzzy rules are constructed: if F>0, K(t) increases, if F<0, K(t) decreases;

[0017] R1:ifFisPBthen△KisPB

[0018] R2:ifFisPMthen△KisPM

[0019] R3:ifFisPSthen△KisPS

[0020] R4:ifFisZOthen△KisZO

[0021] R5:ifFisNSthen△KisNS

[0022] R6:ifFisNMthen△KisNM

[0023] R7:ifFisNBthen△KisNB

[0024] In order to obtain a smaller steady-state error, the upper limit of ΔK is estimated by the integration method, and the upper limit estimate of K(t) is obtained as follows: K*(t)=Gt∫0△Kdt, where G is the integration operator.

[0025] The present invention provides a method for manufacturing a dual-drive vector controller for a brushless DC motor. The dual-drive vector controller of the present invention can realize synchronous control of multiple motors through calculation of back electromotive force characteristics of the brushless DC motor, controller hardware design, controller software control strategy, dual-drive coordination strategy and dual-drive vector controller design, thereby achieving load balance and reasonable distribution effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example:

[0029] like Figure 1 As shown, the embodiment of the present invention provides a method for manufacturing a brushless DC motor dual-drive vector controller, comprising the following steps:

[0030] Step 1: Calculation of the back-EMF characteristics of the brushless DC motor. When the motor is running, only two phases are turned on at the same time. Since the rotor magnetic induction intensity is a trapezoidal distribution, the zero-crossing point can be obtained by measuring the back-EMF of the non-conducting phase, and the rotor position information can be estimated accordingly.

[0031] Step 2: Controller hardware design, the overall control of the brushless DC motor is mainly composed of two parts. Among them, the control and speed regulation module realizes speed regulation and commutation logic control through the control circuit, and drives the motor through the drive circuit; the position detection module mainly estimates the rotor position by obtaining the back electromotive force zero-crossing signal, and feeds it back to the control circuit, calculates the speed and updates the commutation logic state;

[0032] Step 3: Controller software control strategy. The controller software system mainly includes initialization, interrupt service program and subroutine. When the system starts, the initialization part will initialize and assign values ​​to the control system interface, timer, state variables and other parameters. After the initialization is completed, the program enters the main loop, automatically jumps according to the input signal state machine, calls the subroutine and waits for interruption. The interrupt part realizes important functions such as current sampling, communication, commutation, PWM interruption, etc. The subroutine part mainly realizes the start-up and operation logic control of the motor;

[0033] Step 4: Dual-drive collaborative strategy. Taking the stamping machine as an example, when the transmission process produces a periodic characteristic moment of inertia and there is load interference, it will cause speed and displacement deviations in the operation stage of the stamping machine, which makes the motion state in each cycle different from the motion target originally designed. This deviation may cause interference between the dual motors. When adjusting the above deviations, an adaptive sliding mode controller can be established, and the position and speed deviations can be dynamically controlled according to the feedback of the position and speed sensors to ensure that the dual motor drive stage forms a coordinated and synchronized state;

[0034] Step 5: Design of dual-drive vector controller. The servo motor in the stamping machine has a large inherent torque. At this time, there is no need to consider the friction torque caused by viscous damping. In order to improve the applicability of the system, a disturbance function with normal distribution characteristics is constructed.

[0035] In step 1, taking the process of electrical angle 30° to 90° as an example, the high-voltage side MOSFET "V1" is in the PWM (Pulse Width Modulation) state, and the low-voltage side MOSFET "V6" is in the on state, which is the H_PWM-L_ON conduction mode. The current flows in from the motor phase A and flows out from the motor phase B. At this time, the A-phase winding and the B-phase winding are turned on, and the C-phase is suspended. During the operation of the motor, the rotation of the rotor will cause each phase winding to generate an induced back electromotive force. When the electrical angle is 60°, the back electromotive force of the C-phase winding passes through the zero point. Since there is a phase difference of 30° electrical angle between the ideal commutation point and the previous back electromotive force zero point, a 30° electrical angle delayed commutation method is required, that is, commutation is performed at 90°.

[0036] In step 1, ideally, the phase voltage can be obtained by the difference between the neutral point voltage and the terminal voltage, which is the actual neutral point of the winding in the motor model. Taking phase C as an example, the winding voltage equation is explained. When phases A and B are conducting, phase C is not conducting. At this time, the phase voltage of phase C can be expressed as: EC = Uc-Un, where: EC is the back electromotive force of phase C; UC is the voltage between point C and ground; Un is the voltage between point n and ground.

[0037] In step one, the neutral point is usually not connected separately during motor manufacturing, but hidden in the stator winding. The voltage between the neutral point and the ground cannot be directly measured. In order to measure the back electromotive force, three resistors with equal resistance are connected at points A, B, and C to form a star network, and a virtual neutral point m is introduced. From this, we can get: EC=Uc-Um, where Um is the voltage between the virtual neutral point m and the ground.

[0038] In step 2, the control and speed regulation module uses a 16-bit high-performance digital signal controller dsPIC30F series chip dedicated to motor control as the main control chip, and uses a three-phase full-bridge inverter circuit to drive the motor. In the inverter circuit, the high-voltage side MOSFET uses a PWM mode, and the low-voltage side MOSFET uses a constant-on mode (H_PWM-L_ON mode). Since the PWM signal directly output by the dsPIC30F has a low voltage and low power, and its driving capability is insufficient, it cannot directly drive a brushless DC motor. Therefore, it is necessary to build an additional drive circuit in the peripheral circuit to increase the driving power of the PWM signal. The drive circuit is built using an IR2103 drive chip. In addition, a bootstrap circuit can be set around the IR2103 to provide a bootstrap floating power supply. In this way, only one power supply is needed to drive six MOSFETs through three IR2103s, thereby simplifying the drive circuit and saving power.

[0039] In step three, in order to quickly and accurately increase the speed to the rated speed, the motor adopts a three-stage starting method, which mainly includes the following processes: pre-positioning stage, open-loop speed-up stage, and closed-loop speed-up stage.

[0040] In step five, when the system is jittering, it will not be able to reach a stable control state. The gain K(t) of the sliding mode variable structure is compensated by fuzzy control, thereby achieving an adaptive effect. To ensure that the system can quickly reach the sliding surface after being disturbed, the following input and output fuzzy sets are established for the system: F = {NB, NM, NS, ZO, PS, PM, PB}, where: NB, NM, NS are respectively negative large, negative medium, and negative small; ZO is zero; PS, PM, PB are respectively positive small, positive medium, and positive large. The following fuzzy rules are constructed: If F>0, K(t) increases; if F<0, K(t) decreases;

[0041] R1:ifFisPBthen△KisPB

[0042] R2:ifFisPMthen△KisPM

[0043] R3:ifFisPSthen△KisPS

[0044] R4:ifFisZOthen△KisZO

[0045] R5:ifFisNSthen△KisNS

[0046] R6:ifFisNMthen△KisNM

[0047] R7:ifFisNBthen△KisNB

[0048] In order to obtain a smaller steady-state error, the upper limit of ΔK is estimated by the integration method, and the upper limit estimate of K(t) is obtained as follows: K*(t)=Gt∫0△Kdt, where G is the integration operator.

[0049] Specifically, in the pre-positioning stage, the motor structure under study does not have a position sensor installed, and the initial position of the rotor is unknown, so the rotor needs to be moved to the preset position. When starting, the PWM duty cycle is initialized to a lower value, and the two-phase windings of the brushless DC motor are turned on for a short time, so that the rotor can move to the target preset position. In order to prevent the pre-positioning from failing when the direction of the magnetic field generated when the winding is turned on is the same as or opposite to the direction of the rotor magnetic field, the two-phase stator winding that is turned on can be switched again for a second pre-positioning to improve the success rate of the pre-positioning.

[0050] In the open-loop speed-up stage, at low speeds, the back-EMF amplitude is small and difficult to detect, and the zero-crossing position information cannot be identified. Therefore, the molecular pump needs to be accelerated through open-loop control. By setting the PWM duty cycle and the count value of the commutation timer, the corresponding initial voltage and speed-up step can be obtained. In this process, the rotor speed is open-loop controlled and there is no speed feedback adjustment. As the rotor speed increases, the back-EMF amplitude increases, and the controller can detect an obvious back-EMF zero-crossing signal;

[0051] In the closed-loop speed-up stage, when the speed is increased to 10,000 r / min through an open loop, the program can stably detect the back-EMF zero-crossing signal within multiple cycles, and obtain the speed feedback information through calculation. The speed feedback at this time can be used as the input of the PID (Proportional-Integral-Derivative) controller to realize closed-loop control of the motor. During the speed-up process, in order to prevent long-term overcurrent from damaging the motor and controller, when the current is large, the winding will be shut down for a short time, and the speed-up process will be entered again after adjusting the control parameters.

[0052] Table 1: Main technical parameters of the motor

[0053]

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a brushless DC motor dual-drive vector controller, characterized in that: The specific steps include: Step 1: Calculation of the back-EMF characteristics of the brushless DC motor. When the motor is running, only two phases are turned on at the same time. Since the rotor magnetic induction intensity is a trapezoidal distribution, the zero-crossing point can be obtained by measuring the back-EMF of the non-conducting phase, and the rotor position information can be estimated accordingly. Step 2: Controller hardware design. The overall control of the brushless DC motor is mainly composed of two parts. The control and speed regulation module realizes speed regulation and commutation logic control through the control circuit, and drives the motor through the drive circuit; the position detection module mainly estimates the rotor position by obtaining the back electromotive force zero-crossing signal, and feeds it back to the control circuit to calculate the speed and update the commutation logic state; Step 3: Controller software control strategy. The controller software system mainly includes initialization, interrupt service program and subroutine. When the system starts, the initialization part will initialize and assign values ​​to the control system interface, timer, state variables and other parameters. After the initialization is completed, the program enters the main loop, automatically jumps according to the input signal state machine, calls the subroutine and waits for interruption. The interrupt part realizes important functions such as current sampling, communication, commutation, PWM interruption, etc. The subroutine part mainly realizes the start-up and operation logic control of the motor; Step 4: Dual-drive collaborative strategy. Taking the stamping machine as an example, when the transmission process produces a periodic characteristic moment of inertia and there is load interference, it will cause speed and displacement deviations in the operation stage of the stamping machine, which makes the motion state in each cycle different from the motion target originally designed. This deviation may cause interference between the dual motors. When adjusting the above deviations, an adaptive sliding mode controller can be established, and the position and speed deviations can be dynamically controlled according to the feedback of the position and speed sensors to ensure that the dual motor drive stage forms a coordinated and synchronized state; Step 5: Design of dual-drive vector controller. The servo motor in the stamping machine has a large inherent torque. At this time, there is no need to consider the friction torque caused by viscous damping. In order to improve the applicability of the system, a disturbance function with normal distribution characteristics is constructed.

2. The manufacturing method of the brushless DC motor dual-drive vector controller according to claim 1, characterized in that: In step 1, taking the process of electrical angle 30° to 90° as an example, the high-voltage side MOSFET "V1" is in PWM state, and the low-voltage side MOSFET "V6" is in conduction state, which is H_PWM-L_ON conduction mode. The current flows into the motor phase A and flows out of the motor phase B. At this time, the A-phase winding and the B-phase winding are turned on, and the C-phase is suspended. During the operation of the motor, the rotation of the rotor will cause each phase winding to generate an induced back electromotive force. When the electrical angle is 60°, the back electromotive force of the C-phase winding passes through the zero point. Since there is a phase difference of 30° electrical angle between the ideal commutation point and the previous back electromotive force zero point, it is necessary to adopt a 30° electrical angle delayed commutation method, that is, commutation is performed at 90°.

3. The manufacturing method of the brushless DC motor dual-drive vector controller according to claim 1, characterized in that: In step 1, ideally, the phase voltage can be obtained by the difference between the neutral point voltage and the terminal voltage. The actual neutral point of the winding in the motor model is described by taking phase C as an example. When phases A and B are conducting, phase C is not conducting. At this time, the phase voltage of phase C can be expressed as: E C =U c -U n , where: E C is the back electromotive force of phase C; U C is the voltage between point C and ground; U n is the voltage between point n and ground.

4. The manufacturing method of the brushless DC motor dual-drive vector controller according to claim 1, characterized in that: In step 1, the neutral point is usually not connected separately during motor manufacturing, but hidden in the stator winding. The voltage between the neutral point and the ground cannot be directly measured. In order to measure the back EMF, three resistors with equal resistance are connected at points A, B, and C to form a star network, and a virtual neutral point m is drawn. From this, we can get: E C =U c -U m , where: U m is the voltage between the virtual neutral point m and the ground.

5. The manufacturing method of the brushless DC motor dual-drive vector controller according to claim 1, characterized in that: In step 2, the control and speed regulation module uses a 16-bit high-performance digital signal controller dsPIC30F series chip dedicated to motor control as the main control chip, and uses a three-phase full-bridge inverter circuit to drive the motor. In the inverter circuit, the high-voltage side MOSFET adopts the PWM mode and the low-voltage side MOSFET adopts the constant-on mode. Since the PWM signal directly output by the dsPIC30F has low voltage and low power, and the driving ability is insufficient, it cannot directly drive the brushless DC motor. Therefore, it is necessary to build an additional drive circuit in the peripheral circuit to increase the driving power of the PWM signal. The drive circuit is built with an IR2103 drive chip. In addition, a bootstrap circuit can be set around the IR2103 to provide a bootstrap floating power supply. In this way, only one power supply is needed to drive 6 MOSFETs through 3 IR2103s, thereby simplifying the drive circuit and saving power.

6. The manufacturing method of the brushless DC motor dual-drive vector controller according to claim 1, characterized in that: In step 3, in order to quickly and accurately increase the speed to the rated speed, the motor adopts a three-stage starting method, which mainly includes the following processes: Pre-positioning stage, open-loop speed-up stage, and closed-loop speed-up stage.

7. The manufacturing method of the brushless DC motor dual-drive vector controller according to claim 1, characterized in that: In step 5, when the system is jittering, it will not be able to reach a stable control state. The gain K(t) of the sliding mode variable structure is compensated by fuzzy control, thereby achieving an adaptive effect. To ensure that the system can quickly reach the sliding surface after being disturbed, the following input and output fuzzy sets are established for the system: F = {NB, NM, NS, ZO, PS, PM, PB}, where NB, NM, NS are respectively negative large, negative medium, and negative small; ZO is zero; PS, PM, PB are respectively positive small, positive medium, and positive large. The following fuzzy rules are constructed: if F>0, K(t) increases; if F<0, K(t) decreases; R1:ifFisPBthen△KisPB R2:ifFisPMthen△KisPM R3:ifFisPSthen△KisPS R4:ifFisZOthen△KisZO R5:ifFisNSthen△KisNS R6:ifFisNMthen△KisNM R7:ifFisNBthen△KisNB In order to obtain a smaller steady-state error, the upper limit of ΔK is estimated by the integration method, and the upper limit estimate of K(t) is obtained as follows: K*(t)=Gt∫0△Kdt, where G is the integration operator.

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