CN102664576B - Micro-step control method, device and stepping motor controller - Google Patents

Abstract

The present invention is applicable to the electromechanical field, and provides a micro-step control method and device and a stepping motor controller. The method includes the following steps: calculating the cosine current; generating a current compensation function according to the hysteresis curve; The cosine current is compensated to generate a compensation current; the stepper motor is controlled in microsteps through the compensation current. The invention compensates the cosine current according to the hysteresis curve data, uses the compensated current to perform micro-step control on the stepping motor, effectively improves the stepping uniformity of the micro-step control of the stepping motor, realizes high-precision open-loop control, and The structure is simple, the cost is low, the implementation is easy, the workload is small, and the size is small, which can meet the requirements of the mass production process.

Description

A micro-step control method, device and stepping motor controller

technical field

The invention belongs to the electromechanical field, and in particular relates to a micro-step control method, a device and a step motor controller.

Background technique

In order to reduce the step angle of the stepping motor and improve the control accuracy and resolution, the industry generally adopts the cosine current control method to control the motor in microsteps, that is, by applying a cosine control current with a certain phase difference to the winding of the stepping motor, Each full step of the stepping motor is subdivided into more than 2 microsteps to realize microstep control.

However, in the cosine current control method, the hysteresis factor of the iron core seriously affects the uniformity of stepping (and torque) of the stepping motor, and when the stepping motor changes direction, the hysteresis of the core stops the gear Changes in position lag behind control changes, resulting in uneven step sizes and unequal forward and reverse step sizes.

At present, because the traditional open-loop control system realizes micro-step control, the accuracy is usually low, and it is difficult to meet the market's requirements for the precision control of stepper motors. Therefore, two closed-loop control systems are usually used to calibrate the step position to achieve micro-step control. The uniformity of stepping (and torque), one of which is: using position sensors such as photoelectric encoders, magnetic rotary encoders, optical rulers and magnetic rulers to form a feedback loop, and the controller dynamically adjusts the control parameters according to the feedback data to achieve linearity. purpose of position control. The disadvantage of this solution is that expensive position sensors need to be used, the cost is high, and it is difficult to meet the application requirements of compact products due to special requirements for installation dimensions.

The second is: use a photoelectric encoder or a grating ruler to record the step angle mapping table of the stepper motor in advance, store it in the form of a table, and look up the table in reverse according to the target rotation angle to obtain the best step control command. The disadvantage of this solution is that each motor needs to be calibrated separately, the workload is large, and it is difficult to meet the needs of mass production technology. Moreover, since the path of the hysteresis loop is related to the historical state of the soft magnetic core winding, if the winding history When using a unified microstep step angle mapping table when the state is different, the position calibration needs to cover all historical states, and the calibration working range index increases, making it more difficult to meet the needs of mass production technology, especially when changing the direction of motion at different positions , will cause varying degrees of unpredictable errors.

Contents of the invention

The purpose of the embodiment of the present invention is to provide a micro-step control method, aiming to solve the problems of low precision, high cost, large size, large calibration workload and difficulty in meeting the requirements of mass production process in the existing micro-step control method.

The embodiment of the present invention is achieved in this way, a micro-step control method, the method includes the following steps:

calculating the cosine current; obtaining a hysteresis curve function, and approximating the hysteresis curve function to a parallelogram function; generating a current compensation function according to the parallelogram function; compensating the cosine current according to the current compensation function to generate Compensation current; through the compensation current, micro-step control is performed on the stepping motor.

Another object of the embodiments of the present invention is to provide a micro-step control device, which includes:

The current calculation unit is used to calculate the cosine current; the hysteresis curve acquisition module is used to obtain the hysteresis curve function, and the hysteresis curve function is approximated as a parallelogram function; the compensation function generation module is used to obtain the hysteresis curve function according to the parallelogram The function generates a current compensation function; the current compensation unit is used to compensate the cosine current according to the current compensation function to generate a compensation current; the micro-step control unit is used to perform micro-step control on the stepping motor through the compensation current .

Another object of the embodiments of the present invention is to provide a stepping motor controller comprising the above-mentioned micro-stepping control device.

The embodiment of the present invention compensates the cosine current according to the hysteresis curve data, uses the compensated current to perform micro-step control on the stepping motor, effectively improves the step uniformity of the micro-step control of the stepping motor, and realizes high-precision open-loop control , and is simple in structure, low in cost, easy to implement, small in workload and small in size, and can meet the requirements of mass production technology.

Description of drawings

Fig. 1 is the implementation flowchart of the micro-step control method provided by the first embodiment of the present invention;

Fig. 2 is the implementation flowchart of the micro-step control method provided by the second embodiment of the present invention;

3 is a hysteresis curve diagram of the micro-step control method provided by the second embodiment of the present invention;

Fig. 4 (a) is the counterclockwise current compensation diagram of the micro-step control method provided by the second embodiment of the present invention;

Fig. 4 (b) is the clockwise current compensation diagram of the micro-step control method provided by the second embodiment of the present invention;

Fig. 5 is the implementation flowchart of the micro-step control method provided by the third embodiment of the present invention;

Fig. 6 is a magnetic flux state diagram of the micro-step control method provided by the third embodiment of the present invention;

7 is a hysteresis curve generated when the current drops by the micro-step control method provided by the third embodiment of the present invention;

Fig. 8 is a hysteresis curve generated when the current rises by the micro-step control method provided by the third embodiment of the present invention;

FIG. 9 is a diagram showing the relationship between the counterclockwise compensated current waveform and the cosine current in the micro-step control method provided by the third embodiment of the present invention;

Fig. 10 is a comparative relationship diagram between the clockwise compensated current waveform and the cosine current in the micro-step control method provided by the third embodiment of the present invention;

Fig. 11 is a diagram of the relationship between the current waveform and the cosine current after any phase angle change direction compensation of the micro-step control method provided by the third embodiment of the present invention;

Fig. 12 shows the flow chart of realizing the micro-step control method provided by the fourth embodiment of the present invention;

Fig. 13 is a structural diagram of a micro-step control device provided by an embodiment of the present invention;

Fig. 14 is a structural diagram of a first example of a micro-step control device provided by an embodiment of the present invention;

Fig. 15 is a circuit structure diagram of a second example of the micro-step control device provided by the embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The embodiment of the present invention compensates the micro-step control current used for the excitation of the stepping motor according to the data of the hysteresis curve of the soft magnetic body of the motor coil, without needing to calibrate the position of the stepping motor, and simply and effectively improves the stepping speed of the micro-step control of the stepping motor. Uniformity, to achieve high-precision open-loop control.

In the embodiment of the present invention, the cosine current of a certain coil of the motor is used as an example for illustration. The currents of all coils can be implemented in the same way on the basis of considering the phase difference of the cosine current. The phase difference of the cosine current of different coils The calculation is a prior art and will not be repeated here.

Fig. 1 shows the implementation process of the micro-step control method provided by the first embodiment of the present invention, which is described in detail as follows:

In step S101, calculate the cosine current;

In step S102, a current compensation function is generated according to the hysteresis curve;

In the embodiment of the present invention, when the accuracy requirement is not high, the hysteresis curve can be approximated as a parallelogram to simplify the steps of obtaining the current compensation function and improve the non-uniformity of the microstep step. When it is high, the hysteresis curve data can be obtained through the hysteresis curve, and the current compensation function can be calculated according to the hysteresis curve data to achieve precise control.

Of course, the current compensation function can also be calculated manually, and the current compensation function obtained in various ways can be stored for calling when needed.

In step S103, the cosine current is compensated according to the current compensation function to generate a compensation current;

In the embodiment of the present invention, the cosine current is compensated and calculated according to the current compensation function to obtain the compensation current value, and the programmable current control circuit can control the driving circuit to realize the compensation current control, and digital frequency synthesis technology can also be used The method generates a PWM signal, and the power device such as a MOS tube or a Darlington tube is driven by the PWM signal to adjust the current of the coil to realize compensation current control.

In step S104, micro-step control is performed on the stepping motor through the compensation current.

In the embodiment of the present invention, the control current in the motor coil is corrected by the compensation current, and the amount of current variation causes the magnetic flux to change in real time during the process of increasing or decreasing the compensated control current, so as to ensure Effective and real-time micro-step control of the motor through the cosine control current improves the unevenness of micro-stepping and realizes high-precision open-loop control. It has simple structure, low cost, easy implementation, small workload and small size. Small enough to meet the needs of mass production processes.

Fig. 2 shows the implementation flow of the micro-step control method provided by the second embodiment of the present invention, which is described in detail as follows:

In step S201, calculate the cosine current;

In step S202, the hysteresis curve function is obtained, and the hysteresis curve function is approximated as a parallelogram function;

In the embodiment of the present invention, the hysteresis curve is approximated as a parallelogram, and by finding the parallelogram function instead of the hysteresis curve function, the calculation can be greatly simplified and the calibration workload can be reduced, especially for micro-step control that does not require high precision. Improve the step uniformity, the effect is obvious.

In step S203, a current compensation function is generated according to a parallelogram function;

In the embodiment of the present invention, the magnetic flux generated by the magnetization field of the coil current is shown as the dotted dashed line crossing the origin in Fig. 3. It can be seen from Fig. 3 that when the current changes from increasing to decreasing, the current The change of magnetic flux caused by change ΔI is approximately 0; similarly, when the current changes from decreasing to increasing, the change of magnetic flux caused by current change ΔI is also approximately 0.

It can be clearly seen in Figure 3 that when the differential of cosine current to time changes from positive to negative, the compensation function is -ΔI/2; when the differential of cosine current to time changes from negative to positive, the compensation function is ΔI/2. It is worth noting that if the cosine current is a large current, it can be compensated according to the parallelogram function of the peripheral solid line in Figure 3; The parallelogram function formed by the lines is compensated.

In step S204, the cosine current is compensated according to the current compensation function to generate a compensation current;

In step S205, micro-step control is performed on the stepping motor through the compensation current.

Figure 4(a) and Figure 4(b) are the current compensation diagram when the cosine current rotates counterclockwise and the current compensation diagram when the cosine current rotates clockwise, where the dotted line is the cosine current before compensation, which is realized as the cosine after compensation current.

When the cosine current turns counterclockwise, the current drops ΔI at the valley and rises ΔI at the peak; when the cosine current turns clockwise, the current rises ΔI at the valley and drops ΔI at the peak, making the hysteresis loop from One hypotenuse of the parallelogram jumps to another parallel hypotenuse, avoiding hysteresis, thereby realizing step uniformity of micro-step control.

In the embodiment of the present invention, the influence of other windings on the magnetic flux is ignored, and the magnetic flux is considered to be only related to the historical magnetic flux and the current current value, and the hysteresis loop is approximated as a parallelogram, and the compensation function is extracted from the parallelogram to compensate. Under the premise that the precision of micro-step control is not high, the calculation can be greatly simplified, and it has obvious correction effect.

Figure 5 shows the implementation process of the micro-step control method provided by the third embodiment of the present invention, which is described in detail as follows:

In step S301, calculate the cosine current;

In step S302, generate hysteresis curve data when two or two state transitions are made according to a plurality of preset historical states;

In the embodiment of the present invention, the number of historical states is set according to the required number of subdivisions. The number of subdivisions is the number of subdivision step stop positions of the motor in a circular motion. If the number of subdivisions is N, the number of historical states is 4N. Better control accuracy can be obtained. Of course, the number of historical states can be reduced to reduce the measurement workload as required, and the number of historical states can also be increased to improve control accuracy.

As an embodiment of the present invention, the hysteresis curve data includes magnetic flux and current values.

For the same type of motor, if the number of historical states is 4N, divide the magnetic core material into 4N states during operation, and obtain the hysteresis curve data S _n ={F _n , I _n } when two states are switched by measurement , where S _n is the hysteresis curve data in the nth historical state, F _n is the magnetic flux in the nth historical state, and I _n is the current value corresponding to the magnetic flux in the nth historical state, to obtain the pairwise state transition The hysteresis curve data can be obtained through measurement according to actual needs, or part of the hysteresis curve data can be obtained through measurement, and then the rest of the hysteresis curve data can be generated by interpolation to reduce the measurement workload.

Specifically:

a. Calculate the magnetic flux according to the preset historical state number;

The number of historical states is 16, which divides the phase angle of the stepping motor rotation into 16 states, and the subdivision step stop position of the stepping motor is determined by the magnetic flux of each coil, so the phase angle of each state corresponds to a target Magnetic flux (F ₀ -F ₁₆ ), its functional relationship is shown in Figure 6, that is, the subdivision step rotation of the motor is controlled by the magnetic flux of each historical state. In order to meet the constant torque control requirement, the motor subdivision step control target magnetic flux is The function controlling the phase angle is a cosine function, Among them, F is the peak value of magnetic flux, F _n is the magnetic flux in the nth historical state, and n is the serial number of the historical state. Taking a 2-phase motor as an example, the function of the target magnetic flux of the two-phase coils with respect to the phase angle is that the phase difference is 90 degrees Two cosine functions.

b. Obtain the corresponding current value according to the magnetic flux;

In the embodiment of the present invention, the current values I ₀ -I ₁₆ corresponding to the magnetic fluxes F ₀ -F ₁₆ are obtained through calculation or measurement. In the initial state, take the magnetic flux F ₁ as the control target, see Figure 6, gradually increase the current from 0, and monitor the magnetic flux of the coil with a magnetic flux measuring instrument (such as a millitesla meter) until the magnetic flux reaches F ₀ , and Record the current I ₀ at this time to obtain the hysteresis curve data S ₀ ={F ₀ , I ₀ } in this historical state, and then start from S ₀ ={F ₀ , I ₀ }, reduce the current, and at the same time Record the magnetic flux data until the magnetic flux decreases to F ₈ , record the current value I ₈ at this time to obtain the hysteresis curve data S ₈ ={F ₈ , I ₈ } in the eighth historical state, and then increase the current until The magnetic flux increases to F ₁ , record the current value I ₁ at this time, and obtain the hysteresis curve data S ₁ ={F ₁ , I ₁ } in the first historical state, and repeatedly reduce the current until the magnetic flux increases to F ₇ , Record the current value I ₇ at this time, and obtain the hysteresis curve data S ₇ ={F ₇ , I ₇ } in the seventh historical state, increase the current until the magnetic flux increases to F ₂ , record the current value I ₂ at this time, and Obtain hysteresis curve data in the second historical state S ₂ ={F ₂ , I ₂ }, ... S ₁₆ ={F ₁₆ , I ₁₆ }, where S ₀ ={F ₀ , I ₀ } and S ₁₆ = {F ₁₆ , I ₁₆ } are the same, they are the initial position and the end position respectively.

In step S303, the hysteresis curve data when the two states are switched are plotted to generate a hysteresis curve set;

In the embodiment of the present invention, when the current drops, the hysteresis curve data (S ₀ -S ₇ , S ₉ -S ₁₅ ) at each state transition and the hysteresis curve data S ₈ corresponding to the minimum current are respectively compared. 7, where the dotted line is the magnetic flux generated by the magnetization field, and the dotted line C _n is the hysteresis curve generated by interpolation. When the current rises, the hysteresis curve data (S ₁ -S ₁₅ ) Draw points between the hysteresis curve data _S16 corresponding to the maximum current, referring to Fig. 8, wherein the dotted oblique line is the magnetic flux generated by the magnetizing field, so as to obtain multiple hysteresis curves C _{i, j} , the hysteresis curve Corresponding to the function F _{i, j} (I) of the magnetic flux on the current and its inverse function I _{i, j} (F), due to the point curve between S ₇ -S ₁₅ and S ₈ and the point between S ₀ and S ₈ The curves overlap, the plotting curve between S ₁ -S ₇ and S ₁₆ overlaps with the plotting curve between S ₈ and S ₁₆ , so the plotting curve between S ₇ -S ₁₅ and S ₈ can be omitted, and S ₁ - Points between S ₇ and S ₈ to reduce workload.

For example, plot points from S ₀ to S ₈ to obtain a hysteresis curve C _0,8 , which corresponds to the function F _0,8 (I) of the magnetic flux with respect to the current and its inverse function I _0,8 (F), Sequentially plot the hysteresis curve data of any two state transitions (you can filter before plotting to exclude duplicate plots) to generate a hysteresis curve set {C _0,8 ,C _1,8 ,C _2,8 ,C _{3, 8} , C _{4, 8} , C _{5, 8} , C _{6, 8} , C _{7, 8} , C _{8, 9 ,} C _{8, 10, C 8, 11} , C _{8, 12} , C 8 _{, 13} , C _{8, 14} , C _{8, 15} , C _{8, 16} }.

In step S304, a current compensation function is generated according to the hysteresis curve set;

According to {C _0,8 , C _1,8 , C _2,8 , C _3,8 , C _4,8 , C _5,8 , C _6,8 , C _7,8 , C _8,9 , C _{8, 10} , C _{8, 11} , C 8 _{, 12} , C _{8, 13} , C 8, ₁₄ , C _{8, 15} , C _{8, 16} } extract the functions I _{0, 8} (F), I ₁ when various state transitions are performed _{, 8} (F), I _2,8 (F), I _3,8 (F), I _4,8 (F), I _5,8 (F), I _6,8 (F), I _7,8 (F), I _9,8 (F), I _8,10 (F), I 8,11 (F), I _8,12 (F), I _{8,13 (} F), I _8,14 (F ), I _8,15 (F), I _8,16 (F) as the current compensation function.

In step S304, the cosine current is compensated according to the current compensation function to generate a compensation current;

In step S305, micro-step control is performed on the stepping motor through the compensation current.

In the embodiment of the present invention, when it is necessary to control the motor to continue to rotate clockwise, first apply a current of I ₀ to the motor. It is considered that the state of the motor coil is S ₀ at this time, and the magnetic flux of the coil is F ₀ at this time, and then according to the hysteresis curve The current compensation function I _{0, 8} (F) corresponding to C ₀ , 8 compensates the cosine current, and adjusts the change of the current through the driving circuit, and then applies the current I ₀ to the coil sequentially every interval of a time period (determined by the control speed) _{, 8} (F ₇ ), I _{0, 8} (F ₆ ), ..., I _0, 8 (F ₈ ), so far the motor enters the state S ₈ , and then follows the current compensation function corresponding to the hysteresis curve C _{8, 16} I _0,8 (F ₎ , and then apply currents I _8,16 (F ₉ ) _, I _8,16 (F ₁₀ ), . So far, the control of one current cycle has been completed, and the subsequent periodic repetition can realize the stepping motor control of uniform angular velocity. Refer to Figure 9 for the comparison relationship between the compensated current waveform and the cosine current.

When it is necessary to control the motor to continue to rotate in the counterclockwise direction, first apply a current of I ₁₆ to the motor. It is considered that the state of the motor coil is S ₁₆ at this time, and the magnetic flux is F ₁₆ at this time, and then according to the current corresponding to the hysteresis curve C _16,8 Compensation function I _16,8 (F), and then apply current I _16,8 (F ₇ ), I _16,8 (F ₆ ),...,I _{16, 8} (F ₈ ), so far the motor enters the state S ₈ , and then according to the current compensation function I 8, ₀ (F) corresponding to the hysteresis curve C _{8, 0} , and then apply the current I ₈ to the coil sequentially at intervals of a time period _{, 0} (F ₇ ), I _8,0 (F ₆ ), . . . , I _8,0 (F ₀ ). So far, the control of one current cycle is completed, and the subsequent periodic repetition can realize the stepping motor control of uniform angular velocity. See Figure 10 for the control relationship between the control current waveform and the cosine current.

When it is necessary to control the motor to move from clockwise to counterclockwise, the method is similar. The hysteresis curve is selected based on the historical state corresponding to the phase of the steering position, and then the current compensation function is selected according to the hysteresis curve. Finally, the cosine is adjusted according to the compensation function. Perform current compensation to obtain the current value after compensation.

The following example illustrates. Assume that the control task is: first reach the position of 17/16 tooth pitch clockwise, that is, the 405-degree phase position, and then control the motor to move in the reverse direction. During the control process, it is required to keep each microstep of the motor relatively uniform. First, control the motor to move clockwise to a phase of 405 degrees according to the method mentioned above, and the coil state is S ₃ , then select the hysteresis loop C ₃₀ , control the motor to move counterclockwise to a phase of 360 degrees, and the coil state is S ₀ , and then continue According to the anti-clock control method, the control current is applied to implement control, and the anti-clock movement is performed at point *, and the comparison relationship between the compensated current waveform and the cosine current is shown in Figure 11.

It can be understood that the above-mentioned 405° phase angle is just a common phase angle, and the implementer can select any phase angle according to needs, and select the corresponding hysteresis curve in a similar way to realize steering at any phase angle.

All in all, for any coil of the motor, when the cosine current changes from increase to decrease, the control current decreases sharply relative to the cosine current, that is to say, a negative compensation current is applied to the cosine current at this time, and when the cosine current changes from decrease to When not increasing, the control current increases sharply relative to the cosine current, that is to say, a positive compensation current is applied to the cosine current at this time.

Figure 12 shows the implementation process of the micro-step control method provided by the fourth embodiment of the present invention, which is described in detail as follows:

In step S401, the coil magnetic core is degaussed;

In the embodiment of the present invention, the precision is further improved by degaussing the coil core.

In step S402, calculate the cosine current;

In step S403, a current compensation function is generated according to the hysteresis curve;

In step S404, the cosine current is compensated according to the current compensation function to generate a compensation current;

In step S405, micro-step control is carried out to the stepper motor through the compensation current;

In step S406, it is verified whether the micro-step control precision of the motor reaches the preset standard;

If so, perform a null operation;

If not, execute step S407 to increase the number of historical sample states, and return to re-execute step S403.

In the embodiment of the present invention, a high-precision photoelectric encoder can be used to measure the rotation amount of each micro-step of the motor, and calculate the variance value of the rotation amount. If the variance value is greater than the preset standard, the motor micro-step control The accuracy of the motor micro-step control can not reach the preset standard. If the variance value is less than the preset standard, the precision of the motor micro-step control can reach the preset standard.

In the embodiment of the present invention, the control current in the motor coil is corrected by the current compensation function. During the process of the current from increasing to decreasing, the control current decreases sharply relative to the cosine current. When the cosine current changes from decreasing to increasing , the control current increases sharply relative to the cosine current, and the magnetic flux changes accordingly in real time to ensure effective and real-time micro-step control of the motor through the cosine control current, realizing open-loop micro-step control and effectively improving the The step uniformity of the microstep control of the stepping motor is simple in structure, low in cost, easy to implement, small in workload and small in size, and can meet the requirements of mass production technology.

Fig. 13 shows the structure of a micro-step control device provided by an embodiment of the present invention. For convenience of description, only the parts related to the embodiment of the present invention are shown.

As an embodiment of the present invention, the microstep control device can be applied to various stepping motor controllers, and the device includes:

A current calculation unit 71, configured to calculate a cosine current;

A compensation function generation unit 72, configured to generate a current compensation function according to the hysteresis curve;

The current compensation unit 73 is configured to compensate the cosine current according to the current compensation function to generate a compensation current;

The micro-step control unit 74 is used for performing micro-step control on the stepping motor through compensation current.

Fig. 14 shows a first example structure of the micro-step control device provided by the embodiment of the present invention. For convenience of description, only the parts related to the embodiment of the present invention are shown.

The compensation function generating unit 72 includes:

The hysteresis curve function acquisition module 721 is used to acquire the hysteresis curve function and approximate the hysteresis curve function as a parallelogram function;

A compensation function generating module 722, configured to generate a current compensation function according to a parallelogram function.

In the embodiment of the present invention, when the differential of cosine current to time changes from positive to negative, the current compensation function is -ΔI/2; when the differential of cosine current to time changes from negative to positive, the current compensation function The function is ΔI/2.

Fig. 15 shows a second example structure of the micro-step control device provided by the embodiment of the present invention. For the convenience of description, only the parts related to the embodiment of the present invention are shown.

The compensation function generating unit 72 may also include:

The hysteresis curve data acquisition module 723 is used to generate hysteresis curve data when two or two state transitions are made according to a plurality of preset historical states;

The hysteresis curve set generation module 724 is used to describe the hysteresis curve data when the two states are switched, so as to generate the hysteresis curve set;

A compensation function generation module 725, configured to generate a current compensation function according to the hysteresis curve set.

The embodiment of the present invention compensates the cosine current according to the hysteresis curve data, uses the compensated current to perform micro-step control on the stepping motor, realizes the open-loop micro-step control, and effectively improves the step uniformity of the stepping motor micro-step control, Moreover, the structure is simple, the cost is low, easy to implement, the workload is small, and the size is small, which can meet the requirements of mass production technology.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention within.

Claims (8)

1. A micro-step control method, characterized in that said method comprises the steps of: Calculate the cosine current; obtaining a hysteresis curve function, and approximating the hysteresis curve function to a parallelogram function; generating a current compensation function based on the parallelogram function; Compensating the cosine current according to the current compensation function to generate a compensation current; The stepper motor is controlled in microsteps through the compensation current. 2. The method according to claim 1, characterized in that, when the differential of cosine current to time changes from positive to negative, the current compensation function is -ΔI/2; when the differential of cosine current to time changes from negative to When it becomes positive, the current compensation function is ΔI/2. 3. The method according to claim 1, wherein the step of generating the current compensation function according to the hysteresis curve is specifically: Generate hysteresis curve data for pairwise state transitions according to multiple preset historical states; Depicting the hysteresis curve data to generate a hysteresis curve set; A current compensation function is generated from the set of hysteresis curves. 4. The method according to claim 1, further comprising the following steps before the step of calculating cosine current: Demagnetize the coil core. 5. method as claimed in claim 1, is characterized in that, also comprises the following steps after described stepper motor is carried out micro-step control step by described compensating electric current: Verify whether the motor micro-step control accuracy reaches the preset standard; If so, perform a null operation; If not, increase the number of historical sample states, and return to re-execute the step of generating the current compensation function according to the hysteresis curve. 6. A micro-step control device, characterized in that the device includes a current calculation unit, a compensation function generation unit, a current compensation unit and a micro-step control unit, and the compensation function generation unit includes a hysteresis curve acquisition module and a compensation function Generate modules; The current calculation unit is used to calculate cosine current; The hysteresis curve function acquiring module is used to acquire the hysteresis curve function and approximate the hysteresis curve function as a parallelogram function; The compensation function generation module is used to generate a current compensation function according to the parallelogram function; The current compensation unit is configured to compensate the cosine current according to the current compensation function to generate a compensation current; The micro-step control unit is used for performing micro-step control on the stepping motor through the compensation current. 7. The device according to claim 6, wherein the compensation function generating unit comprises: The hysteresis curve data acquisition module is used to generate hysteresis curve data when two or two state transitions are made according to a plurality of preset historical states; A hysteresis curve set generating module, configured to describe the hysteresis curve data to generate a hysteresis curve set; A compensation function generating module, configured to generate a current compensation function according to the set of hysteresis curves. 8. A stepping motor controller, characterized in that, the micro-step control device in the stepping motor controller is the micro-step control device according to any one of claims 6 to 7.