CN103684184B - A kind of linear motor initial phase determination method - Google Patents

Abstract

A method for determining the initial phase of a linear motor. This method sequentially passes six currents with three different electrical angle phases and opposite directions under each phase into the coil array as the motor mover to make the mover move. Using a sensor Measure the acceleration of the mover under each current, and calculate the initial phase value of the motor through a certain algorithm. The invention only needs the motor mover to perform short-distance movement, and the acceleration measured by the sensor can be used to solve the high-precision initial phase through simple calculation. The invention has ingenious conception and convenient operation, and can determine the initial phase of the linear motor by means of a simple algorithm without adding hardware.

Description

A method for determining the initial phase of a linear motor

technical field

The invention relates to a method for determining the initial phase of a linear motor, in particular to a method for solving the spatial phase of a stator magnetic field by using the displacement of a motor mover.

Background technique

Linear motors have a series of advantages such as simple structure, fast dynamic response, high speed and acceleration, high precision, low vibration and noise, etc., and become an ideal transmission method for various high-speed, precision machine tools and integrated circuit manufacturing equipment. Traditional linear motors include the use of flexible hinges, piezoelectric stacks, screw sliding, and air-floating motion workbenches. With the development of micro-nano manufacturing technology, the magnetic levitation linear motor has developed rapidly in recent years. It has the advantages of non-contact, friction-free, and wear-free, and it is easy to achieve nano-level positioning accuracy and large-stroke motion. This makes linear motors have broader application prospects in the fields of semiconductor lithography, precision machining, micro-assembly, nanotechnology and fine motion control.

In order to improve the control effect and obtain good dynamic speed regulation characteristics, vector control technology has become an important control method for linear motors. In the control system based on vector control technology, the determination of the initial phase is one of the keys that affect the system performance. If the initial phase cannot be accurately determined when the system is powered on, the system will not be able to correctly complete a series of algorithms of linear vector control, resulting in chaotic motion of the linear motor, or even failure to start. Based on this, many scholars have carried out research on the initial phase determination of linear motors. In the research paper "Initial Phase Finding and Measurement of Electric Angle in Permanent Magnet Synchronous Linear Motor Vector Control System, Micro Motors, 2009, 42 (11), 1~6", a method for initial phase determination is proposed, that is, in the linear motor Install a proximity switch at the end, and ensure that the grating scale has a Z-axis pulse within the range that the proximity switch can detect. Logically AND the Z-axis pulse of the grating ruler and the output signal of the proximity switch, and use this signal to control the reset of the counter. After the system is powered on, the linear motor moves toward the zero point at a certain speed. When the system detects the Z-axis pulse at the end of the motor, the counter reset signal is valid, and the counter is cleared. At this time, the position of the motor is the zero point. In the research paper "Research on Control Technology of H-type Linear Motor Workbench, Machine Tool and Hydraulics, 2007, 35(10), 130-132", a method to realize bilateral synchronous phase finding based on incremental encoder was proposed. Although the above studies have solved the problem of high-precision determination of the initial phase to a certain extent in certain applications, they either use additional devices to cause complex mechanisms and increase costs; or due to the use of low-precision sensors and solving algorithms Cause phase finding accuracy is low.

Contents of the invention

Considering the defects of the above solutions, the present invention proposes a method for determining the initial phase of a linear motor: six currents with three different electrical angle phases and opposite directions in each phase are sequentially passed into the coil of the motor mover In the array, move the mover, use the sensor to measure the acceleration of the mover under each current, and calculate the initial phase value of the motor through a certain algorithm. This method does not increase any hardware cost, is simple to operate, and has strong versatility. It has great application potential in determining the initial phase of a linear motor.

Technical scheme of the present invention is as follows:

A method for determining the initial phase of a linear motor, the linear motor includes a motor stator and a motor mover, characterized in that the method includes the following steps:

1) First pass a current with amplitude and phase (I _m ,0) to the coil array;

2) Use the displacement sensor as the closed-loop feedback sensor of the motor mover control system, so that the displacement of the motor mover is an integer multiple of the motor pole pitch τ;

3) Use the acceleration sensor to measure the acceleration a ₁₁ at the moment when the motor mover starts to move;

4) Repeat steps (1) to (3), respectively input the amplitude and phase as (-I _m ,0), (I _m ,π/2), (-I _m ,π/2), (I The currents of _m ,-π/2) and (-I _m ,π/2) respectively measure the accelerations a ₁₂ , a ₂₁ , a ₂₂ , a ₃₁ and a ₃₂ at the moment when the motor mover starts to move. Through these six Acceleration uses the following formula:

Calculate the initial phase Where a ₁ , a ₂ and a ₃ are intermediate variables; a ₁ =a ₁₁ -a ₁₂ , a ₂ =a ₂₁ -a ₂₂ , a ₃ =a ₃₁ -a ₃₂ .

Adopting above technical scheme can make the present invention obtain following technical effect:

①Easy to operate, only need to pass six kinds of currents into the coil array, by detecting the acceleration value under each current, the initial phase value can be calculated by simple calculation;

②The whole system does not need to add additional sensors, saving hardware costs.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of an initial phase measuring device using a moving coil magnetic levitation linear motor as an example using the method of the present invention.

Among them, 1-motor stator; 2-magnetic steel array; 3-displacement sensor; 4-coil array; 5-motor mover; 6-signal line; 7-signal processing circuit; 8-driver; 9-driver line; 10 -Accelerometer.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a schematic diagram of the installation structure of each component of the present invention, taking the moving coil type magnetic levitation linear motor as an example and adopting the initial phase determination method, including: motor stator 1, magnetic steel array 2, displacement sensor 3, coil array 4, motor mover 5. Signal line 6, signal processing circuit 7, driver 8, driver line 9 and acceleration sensor 10.

Let the initial phase of the motor be The pole pitch of the motor is τ, and the displacement of the mover 5 of the m motor is x _m at a certain moment, then the magnetic angle phase of the motor is Assume that the coil array 4 on the motor mover 5 has an input amplitude of I _m and a phase of current, according to the motor thrust model, the acceleration model of the motor mover 5 at time m is:

Where k is a constant, a _f is the acceleration value corresponding to the friction force;

The method comprises the steps of:

(1) Make the driver 8 pass a current with amplitude and phase (I _m ,0) to the coil array 4 through the driver line 9;

(2) Use the displacement sensor 3 as the closed-loop feedback sensor of the control system of the motor mover 5, so that its displacement is an integer multiple of the pole distance τ of the motor;

(3) Using the acceleration sensor 10 to measure the acceleration a ₁₁ at the moment when the motor mover 5 starts to move;

(4) Repeat steps (1) to (3), and input the amplitude and phase as (-I _m ,0), (I _m ,π/2), (-I _m ,π/2), (I The currents of _m ,-π/2) and (-I _m ,π/2) respectively measure the accelerations a ₁₂ , a ₂₁ , a ₂₂ , a ₃₁ and a ₃₂ at the moment when the electric mover 5 starts to move. According to the acceleration model, the expressions of these six accelerations can be obtained as follows:

(Ι) formula and (II) formula are subtracted, can get:

Subtracting formula (Ⅲ) and formula (Ⅳ), we can get:

(Ⅴ) formula and (Ⅵ) formula subtraction, can get:

Subtract the formula (Ⅷ) from the formula (IX) to get:

From (Ⅶ) formula～(Ⅸ) formula can get:

From (X) formula and (XI) formula can be solved

Wherein a ₁ , a ₂ and a ₃ are intermediate variables, which are respectively determined by formulas (VII), (VIII) and (IX).

In addition, the acceleration of the motor mover 5 can be obtained by the displacement sensor 3 , that is, the displacement value measured by the displacement sensor 3 can be obtained after the second derivation.

Example

Reference is made to Figure 1 for a better understanding of the present invention.

The coefficient k=100m·s ^-2 ·A ^-1 , the current amplitude I _m =1A that passes through the coil array 4 on the motor mover 5 each time, and the acceleration value a _f corresponding to the friction force = 1m·s ^-2 .

1) Make the driver 8 pass a current with amplitude and phase (1,0) to the coil array 4 through the driver line 9;

2) Use the displacement sensor 3 as the closed-loop feedback sensor of the control system of the motor mover 5, so that its displacement is twice the pole distance τ of the motor;

3) Use the acceleration sensor 10 to measure the acceleration a ₁₁ =49m·s ⁻² at the moment when the motor mover 5 starts to move;

4) Repeat steps (1) to (3), respectively input the amplitude and phase as (-1,0), (1,π/2), (-1,π/2), (1,-π /2) and (-1, π/2), the measured accelerations at the moment when the motor mover 5 starts to move are respectively a ₁₂ =-49m·s ^-2 , a ₂₁ =-87.6m·s ^-2 , a ₂₂ =87.6m·s ^-2 , a ₃₁ =85.6m·s ^-2 , a ₃₂ =-85.6m·s ^-2 , according to formulas (Ⅶ)～(Ⅸ), a ₁ =a ₁₁ - a ₁₂ =98m·s ^-2 , a ₂ =a ₂₁ -a ₂₂ =-175.2m·s ^-2 , a ₃ =a ₃₁ -a ₃₂ =171.2m·s ^-2 , according to formula (ⅩⅡ), it can be solved have to

Through the above steps, in terms of hardware, there is no need to add additional sensors, only the displacement sensor that uses the servo closed-loop feedback of the motor itself; Short-distance motion and continuous collection of the acceleration at the beginning of each motion, the initial phase of the motor can be accurately calculated by using a simple algorithm.

Claims (1)

1. a linear motor initial phase determination method, these linear electric motors include motor stator (1) and electric mover (5), it is characterised in that described method comprises the steps:

1) coil array (4) is passed first into amplitude and phase place for (I_m, 0) electric current；

2) utilize displacement transducer (3) to control the closed loop feedback sensor of system as electric mover (5), make the integral multiple that displacement is motor pole span τ of electric mover (5)；

3) acceleration transducer (10) is utilized to measure the acceleration a in electric mover (5) setting in motion moment₁₁；

4) step 1 is repeated)～3), each lead into amplitude and phase place respectively (-I_m,0)、(I_m,π/2)、(-I_m,π/2)、(I_m,-pi/2) and (-I_m, pi/2) electric current, record the acceleration a in electric mover (5) setting in motion moment respectively₁₂、a₂₁、a₂₂、a₃₁And a₃₂, utilize following equation by these six acceleration:

Calculate initial phaseWherein a₁、a₂And a₃For intermediate variable；A₁=a₁₁-a₁₂, a₂=a₂₁-a₂₂, a₃=a₃₁-a₃₂。