Stepping motor driving device and driving control method

Abstract

The invention provides a stepping motor driving device and a driving control method, and belongs to the technical field of motor control, and the stepping motor driving device comprises a motor control unit, a digital-to-analog conversion unit, an analog driving unit, a current detection unit and a stepping motor. The method comprises the steps that the motor control unit generates two paths of N sections of sine and cosine digital driving signals with the phase difference of 90 degrees, analog quantity is generated through the digital-to-analog conversion unit, and signal matching adjustment is completed through the A-path signal conditioning unit and the B-path signal conditioning unit of the analog driving unit. At the same time, the drive control unit completes the on-off control of the upper and lower bridge arms of the corresponding H bridge, and transmits the drive signals to the A and B motor simulation drive circuits, and finally achieves the real-time control of the motor drive current through hardware-level negative feedback. According to the driving device and the driving control method, hardware PWM control is not needed, current overshoot and fluctuation are effectively eliminated, switching noise is reduced, motor heating is reduced, and stepping precision is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control, in particular to a kind of stepper motor driving device and driving control method. BACKGROUND

[0002] Stepper motor is a kind of control motor that converts electric pulse signal into angular displacement and linear displacement, and is widely used in numerical control machine tool, medical surgical instrument, production line and other fields.The traditional control method of stepper motor is pulse control, and the motor rotates a certain angle for each pulse received, and the rotation accuracy is limited by the step angle, which cannot meet the requirements of high-precision control.In order to solve this problem, micro-step control of stepper motor appears, and there are voltage type drive and current type drive for micro-step control of stepper motor.The voltage type drive forms PWM modulation wave control H bridge by using 90 degree phase difference sine voltage modulation wave and triangle wave, but the drive current is uncontrollable, and the motor vibrates and generates heat seriously when the current is too large, and the motor is easy to stall when the current is too small.The traditional current type drive controls the switching state of H bridge switching tube by PWM pulse width modulation, and then controls the size of motor current, but the H bridge switching tube is in frequent switching state, the noise is large, the current overshoot fluctuation is large, and the motor generates heat obviously.To solve this problem, fine control algorithm and real-time response capability are needed, which requires higher motor controller. SUMMARY

[0003] The technical problem to be solved by the present application is to solve the problem of traditional current type micro-step control, that is, the transistor works in frequent switching state due to PWM control, the motor winding current overshoot and fluctuation is large, the control loop noise is too large, and the motor generates heat obviously without increasing the cost of controller.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0005] A kind of stepper motor driving device includes: motor control unit, digital-analog conversion unit, analog drive unit, current detection unit and stepper motor,

[0006] The motor control unit generates two digital quantities containing N items of sine and cosine information according to the sine function digital-analog conversion table, wherein N is an even number greater than or equal to 2, and simultaneously receives the feedback signal of the current detection unit for fine tuning the output digital quantity;

[0007] The digital-analog conversion unit receives the two digital quantities output by the motor control unit and converts them into approximate two N-term sine voltage values as the given quantity of the analog drive unit;

[0008] The analog drive unit receives the given quantity output by the digital-analog conversion unit and generates N constant sine current values by hardware negative feedback for driving the stepper motor.

[0009] Current detection unit, real-time monitoring of the current value of the analog drive unit output, for motor control unit fine-tuning output digital;

[0010] Stepping motor, for two-phase hybrid stepping motor, is the control object of the driving device.

[0011] Further, the analog drive unit comprises: A signal conditioning circuit, B signal conditioning circuit, drive control circuit, A motor analog drive circuit, B motor analog drive circuit,

[0012] A signal conditioning circuit, receiving the analog signal 1 output by the digital-to-analog conversion unit, and adjusting the amplitude and polarity of the signal, for adapting the A motor analog drive circuit;

[0013] B signal conditioning circuit, receiving the analog signal 2 output by the digital-to-analog conversion unit, and adjusting the amplitude and polarity of the signal, for adapting the B motor analog drive circuit;

[0014] Drive control circuit, comprising logic circuit and signal switch, drive control circuit receiving analog signal output by A signal conditioning circuit and B signal conditioning circuit, and according to the control signal output by the motor control unit, control signal switch sends the adjusted analog signal 1 and analog signal 2 to the control end of the respective H-bridge upper arm transistor, and at the same time controls the logic circuit to complete the corresponding conduction and disconnection of the respective H-bridge lower arm;

[0015] A motor analog drive circuit, receiving the analog signal processed by A signal conditioning circuit output by drive control circuit, and converting it into N constant current signals conforming to the sine law through hardware negative feedback;

[0016] B motor analog drive circuit, receiving the analog signal processed by B signal conditioning circuit output by drive control circuit, and converting it into N constant current signals conforming to the cosine law through hardware negative feedback.

[0017] Further, the analog signals output by the A motor analog drive circuit and the B motor analog drive circuit are 90° out of phase.

[0018] Further, the A motor analog drive circuit and the B motor analog drive circuit each comprise: left error amplifier circuit, left gain adjustment circuit, left current sampling circuit, right error amplifier circuit, right gain adjustment circuit, right current sampling circuit, H-bridge circuit;

[0019] Left error amplifier circuit, receiving the output signals of signal conditioning circuit and left current sampling circuit, and subtracting to obtain left given error signal;

[0020] The left gain adjustment circuit receives the left given error signal and adjusts the amplitude, polarity, and rise time of the signal.

[0021] The left current sampling circuit and the right current sampling circuit sample the current signal output by the H-bridge in real time.

[0022] The right error amplification circuit receives the output signals of the signal conditioning circuit and the right current sampling circuit and obtains the right given error signal by subtraction.

[0023] The right gain adjustment circuit receives the right given error signal and adjusts the amplitude, polarity, and rise time of the signal.

[0024] The H-bridge circuit receives the error signal output by the gain adjustment circuit and drives the stepper motor under the logic control of the drive control circuit.

[0025] Further, the left error amplification circuit and the right error amplification circuit are subtraction circuits built with operational amplifiers or transistors, the signal bandwidth of the operational amplifiers or transistors is greater than 10 MHz, the signal gain ratio is greater than 60 dB, and the input bias current is less than 10 nA.

[0026] Further, the left gain adjustment circuit and the right gain adjustment circuit are integral circuits built with operational amplifiers, the signal bandwidth is greater than 10 MHz, the signal gain ratio is greater than 60 dB, and the input bias current is less than 10 nA.

[0027] Further, the left current sampling circuit and the right current sampling circuit are multi-stage differential proportional circuits composed of instrument amplifiers or operational amplifiers, the offset voltage of the instrument amplifiers and the operational amplifiers does not exceed 10 μV, the temperature drift voltage does not exceed 5 μV / °C, the input bias current does not exceed 100 pA, and the signal bandwidth is greater than 10 MHz.

[0028] According to another aspect of the present application, a method for driving and controlling a stepper motor is provided, which comprises the following steps:

[0029] S100. The motor control unit establishes a set of digital-to-analog conversion value table according to a sine function, the value table has N items, each item corresponds to an angle ;

[0030] S200. The motor control unit calls the value table to generate two N-item positive and negative sine digital signals with a phase difference of 90° and sends them to the digital-to-analog conversion unit to be converted into analog signals.

[0031] S300. The analog drive unit generates two positive and negative sine motor drive signals with a phase difference of 90° under the control of the motor control unit to drive the operation of the stepper motor.

[0032] S400.In the whole control process, the motor control unit samples the current flowing through the motor winding in real time through the current detection unit, compares it with the set current, and adjusts the value of the motor drive signal in real time to ensure the stability and accuracy of the motor winding current.

[0033] Further, the control method of the analog drive unit further comprises: the period of the A and B two-way sine signals generated by the digital-to-analog conversion unit is T, the starting angle of the A way is 0°, the starting angle of the B way is 90°, and the output time of each step is ,

[0034] After the motor is started, the motor control unit extracts the Xth item from the two sets of function tables respectively, generates two-way motor drive given signals with a phase difference of 90°, X represents a specific item in the numerical table, and the initial value is 1, and simultaneously controls the devices of the A and B two-way H-bridge through the drive control circuit , , , corresponding turn-on and turn-off, to generate a constant drive current, wherein , , , represent the transistors constituting the upper and lower arms of the H-bridge, the timer synchronously controls the current loading time of each item, and the Nth data of the digital-to-analog conversion numerical table in a period is sequentially sent out as a given signal to form a sine current, thereby completing the drive control of the stepper motor in one period.

[0035] The present application has the advantages that: without PWM control, the motor drive current is controlled in real time through hardware-level negative feedback, eliminating current overshoot and fluctuation; the H-bridge upper arm transistor works in the saturation region, without frequent switching, which can effectively reduce switching noise, thereby reducing motor heating and improving stepping accuracy; at the same time, the circuit has low requirements for software algorithm, reducing the requirements for the motor controller. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Schematic diagram of the stepper motor drive device;

[0037] Figure 2 Schematic diagram of the analog drive unit;

[0038] Figure 3 Schematic diagram of the current detection unit circuit;

[0039] Figure 4 Schematic diagram of the A-way signal conditioning circuit;

[0040] Figure 5 Schematic diagram of the A-way motor analog drive circuit;

[0041] Figure 6 Left error amplifier circuit schematic diagram;

[0042] Figure 7 Left gain adjustment circuit schematic diagram;

[0043] Figure 8 Left current sampling circuit schematic diagram;

[0044] Figure 9 Stepping motor drive control method schematic diagram;

[0045] Label explanation:

[0046] 1, motor control unit; 2, digital-to-analog conversion unit; 3, analog drive unit; 4, current detection unit; 5, stepping motor; 31, A signal conditioning circuit; 32, B signal conditioning circuit; 33, drive control circuit; 34, A motor analog drive circuit; 35, B motor analog drive circuit; 341, left error amplifier circuit; 342, left gain adjustment circuit; 343, H-bridge circuit; 344, right gain adjustment circuit; 345, right error amplifier circuit; 346, left current sampling circuit; 347, right current sampling circuit. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without any inventive effort fall within the scope of protection of the present application.

[0048] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the usual meaning understood by a person of ordinary skill in the art to which the present application pertains. The terms "first", "second" and similar words used in the present application do not represent any order, number or importance, but are only used to distinguish different components. The terms "include" or "contain" and similar words mean that the elements or objects before the words cover the elements or objects listed after the words and their equivalents, without excluding other elements or objects. The terms "connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "up", "down", "left", "right" and the like are only used to represent relative positional relationships, which may change accordingly when the absolute positions of the described objects change.

[0049] To keep the following description of the embodiments of the present invention clear and concise, detailed descriptions of some known functions and components have been omitted.

[0050] Please refer to the figure; the embodiment of the present invention is as follows:

[0051] like Figure 1 As shown, a stepper motor drive device includes a motor control unit 1, a digital-to-analog converter 2, an analog drive unit 3, a current detection unit 4, and a stepper motor 5. The motor control unit 1 is electrically connected to the digital-to-analog converter 2, the motor control unit 1 is electrically connected to the current detection unit 4, the motor control unit 1 is electrically connected to the analog drive unit 3, the digital-to-analog converter 2 is electrically connected to the analog drive unit 3, the analog drive unit 3 is electrically connected to the current detection unit 4, and the analog drive unit 3 is electrically connected to the stepper motor 5.

[0052] like Figure 2 As shown, the analog drive unit 3 includes an A-channel signal conditioning circuit 31, a B-channel signal conditioning circuit 32, a drive control circuit 33, an A-channel motor analog drive circuit 34, and a B-channel motor analog drive circuit 35. The A-channel signal conditioning circuit 31 is electrically connected to the drive control circuit 33, the B-channel signal conditioning circuit 32 is electrically connected to the drive control circuit 33, the drive control circuit 33 is electrically connected to the A-channel motor analog drive circuit 34, and the drive control circuit 33 is electrically connected to the B-channel motor analog drive circuit 35.

[0053] like Figure 3 As shown, the current detection unit 4 is implemented using a two-stage proportional circuit built with an operational amplifier having an offset voltage of 5μV, a temperature drift voltage of 1μV / ℃, an input bias current of 50pA, and a signal bandwidth of 20MHz.

[0054] like Figure 4 As shown, the signal conditioning circuit 31 for channel A is implemented using an operational amplifier with a signal bandwidth of 20MHz, a common-mode rejection ratio of 100dB, and an input bias voltage of 0.5mV, and is constructed using a three-stage proportional amplifier circuit. The signal conditioning circuit 32 for channel B is the same as that for channel A, and will not be described in detail here.

[0055] like Figure 5As shown, the A-path motor analog drive circuit 34 includes a left-side error amplifier circuit 341, a left-side gain adjustment circuit 342, a left-side current sampling circuit 346, an H-bridge circuit 343, a right-side gain adjustment circuit 344, a right-side error amplifier circuit 345, and a right-side current sampling circuit 347. The left-side error amplifier circuit 341 is electrically connected to the drive control circuit 33 through a first input terminal 3411. The left-side error amplifier circuit 341 is electrically connected to the left-side gain adjustment circuit 342. The left-side gain adjustment circuit 342 is electrically connected to the left-side transistor control terminal of the upper bridge arm of the H-bridge circuit 343. The left-side transistor control terminal of the lower bridge arm of the H-bridge circuit 343 is electrically connected to the drive control circuit 33 through a second input terminal 3431. The left-side error amplifier circuit 341 is electrically connected to the left-side current sampling circuit 346. The sampling circuit 346 is connected to the current output terminal of the lower bridge arm transistor of the H-bridge circuit 343. The right error amplifier circuit 345 is electrically connected to the drive control circuit 33 through the third input terminal 3451. The right error amplifier circuit 345 is electrically connected to the right gain adjustment circuit 344. The right gain adjustment circuit 344 is electrically connected to the control terminal of the right transistor of the upper bridge arm of the H-bridge circuit 343. The control terminal of the right transistor of the lower bridge arm of the H-bridge circuit 343 is electrically connected to the drive control circuit 33 through the fourth input terminal 3432. The right error amplifier circuit 345 is electrically connected to the right current sampling circuit 347. The right current sampling circuit 347 is electrically connected to the current output terminal of the lower bridge arm transistor of the H-bridge circuit 343. The circuit structure of the B-channel motor analog drive circuit 35 is the same as that of the A-channel motor analog drive circuit 34, and will not be described again.

[0056] The motor control unit 1 is implemented using an STM32 microcontroller with a main frequency of 72MHz; the digital-to-analog converter unit 2 is implemented using a digital-to-analog converter chip with a conversion time of 5µs, a nonlinearity of 0.35LSB, and a 12-bit resolution; the logic circuit in the drive control circuit 33 is a logic selection circuit built using CMOS level AND gates and inverters, and the signal switch is an analog switch with a conduction impedance of 50Ω; the H-bridge circuit 343 is implemented using MOS transistors with a drain-source on-resistance of 10mΩ and a total gate charge of 5nC.

[0057] like Figure 6 As shown, the error amplifier circuit 341 on the left is implemented using a subtraction circuit built with an operational amplifier having a signal bandwidth of 20MHz, a signal gain of 100dB, and an input bias current of 5nA; the error amplifier circuit 345 on the right is the same as the error amplifier circuit 341 on the left, and will not be described again.

[0058] like Figure 7 As shown, the gain adjustment circuit 342 on the left is implemented using an integral circuit built with an operational amplifier with a signal bandwidth of 20MHz, a signal gain of 100dB, and an input bias current of 5nA; the gain adjustment circuit 344 on the right is the same as the gain adjustment circuit 342 on the left, and will not be described again.

[0059] As shown in Figure 8 , the left current sampling circuit 346 adopts a two-stage differential proportional circuit composed of an operational amplifier with an offset voltage of 5 μV, a temperature drift voltage of 1 μV / °C, and an input bias current of 50 pA, and the right current sampling circuit 347 is consistent with the left current sampling circuit 346 and will not be described again.

[0060] According to another aspect of the present application, the driving control method of the stepper motor is:

[0061] S100. The motor control unit 1 establishes a set of digital-to-analog conversion numerical table according to the sine function, the numerical table has N items, and each item corresponds to an angle ;

[0062] S200. The motor control unit 1 calls the numerical table to generate two sets of N-item sine and cosine function tables with a phase difference of 90°, and sends the digital quantity in the function table to the digital-to-analog conversion unit to be converted into an analog quantity;

[0063] S300. The analog driving unit 3 generates two paths of sine and cosine motor driving signals with a phase difference of 90° under the control of the motor control unit 1 to drive the operation of the stepper motor 5;

[0064] S400. During the entire control process, the motor control unit 1 samples the current flowing through the motor winding in real time through the current detection unit 4, compares it with the set current, and adjusts the value of the motor driving signal in real time to ensure the stability and accuracy of the motor winding current.

[0065] As shown in Figure 9 , the specific control method of the analog driving unit 3 further includes:

[0066] S310. After the motor is started, the motor control unit 1 sends the Xth item of the two sets of sine and cosine function tables to the digital-to-analog conversion unit 2, X represents a specific item in the sine and cosine function table, and the initial value is 1. The given quantity is converted through the digital-to-analog conversion unit 2, processed through the A path signal conditioning circuit 31 and the B path signal conditioning circuit 32, and the motor driving given signal is generated. At the same time, the drive control circuit 33 receives the signal of the motor control unit 1 to control the left lower bridge arm transistor of the A path motor analog driving circuit 34 and the B path motor analog driving circuit 35 to be turned off, and the right lower bridge arm transistor of the A path motor analog driving circuit 34 and the B path motor analog driving circuit 35 to be turned on. The drive control circuit 33 connects the A path signal conditioning circuit 31 and the B path signal conditioning circuit 32 to the first input end 3411 of the A path motor analog driving circuit 34 and the B path motor analog driving circuit 35 through the signal switch, and disconnects the third input end 3451 at the same time. The motor driving given quantity is controlled through the left error amplifier circuit and the left gain adjustment circuit to control the left upper bridge arm transistor Conduct, motor winding Flow through the current is , the timer of the motor control unit starts timing, and the timing reaches After that, the timer resets and re-timing;

[0067] S320. The motor control unit extracts X+1 items from the two sets of sine and cosine function tables, converts them through the digital-to-analog conversion unit, and sends them to the A signal conditioning circuit 31 and the B signal conditioning circuit 32, respectively, changes the left upper bridge arm transistor Conduct impedance, so that the motor winding Flow through the current is , and so on, the motor control unit controls the motor winding Flow through the corresponding current;

[0068] S330. When , the motor control unit 1 controls the left lower bridge arm transistor Closed, control the right lower bridge arm transistor Disconnect, at the same time, make the A signal conditioning circuit 31 and the B signal conditioning circuit 32 respectively disconnected with the first input end 3411 of the A motor analog drive circuit 34 and the B motor analog drive circuit 35, and connected with the third input end 3451, and a given amount is controlled through the right error amplifier circuit and the right gain adjustment circuit. The right upper bridge arm transistor Conduct, motor winding Flow through the corresponding current, the timer of the motor control unit starts timing, and the timing reaches After that, the timer resets and re-timing;

[0069] S340. When , the step motor drive device completes a period of load, and then repeats the above process to complete the driving of the step motor.

[0070] The principle of the application is: the motor control unit generates two sets of sine function tables with a phase difference of 90° according to the sine function, outputs the given amount of positive and negative sine with a phase difference of 90° to the A and B paths through the digital-to-analog conversion unit, adjusts the amplitude and polarity of the given amount by the A signal conditioning unit and the B signal conditioning unit, controls the H bridge corresponding bridge arm to be turned on and turned off by the drive control circuit, and finally the A motor analog drive unit and the B motor analog drive unit realize the step motor winding current to change periodically according to the sine law through the hardware level negative feedback, without PWM control, so as to complete the micro-step control of the step motor.

[0071] In summary, the application provides a kind of stepper motor driving device and driving control method, the circuit uses single-chip microcomputer as controller, without PWM control, through the mode of hardware level negative feedback, realizes the sinusoidal regularity change of stepper motor winding current, thereby avoids transistor to work in the state of frequent switching, eliminates motor winding current overshoot and fluctuation, reduces control loop noise, thereby obviously improves the problem of motor heating, and improves control precision.

[0072] The above is only the embodiment of the application, and does not limit the patent scope of the application, and any equivalent transformation or direct or indirect application in the related technical field using the content of the application specification and drawings is also included in the patent protection scope of the application.

Claims

1. A stepper motor drive device, characterized in that... The motor control unit generates two digital signals containing N positive and negative sine information according to a sine function digital-to-analog conversion table, wherein N is an even number greater than or equal to 2, and simultaneously receives feedback signals from the current detection unit in real time for fine-tuning the output digital signals; The digital-to-analog conversion unit receives the two digital signals output by the motor control unit and converts them into approximate N-term sine voltage values as the given signals of the analog drive unit; The analog drive unit receives the given signals output by the digital-to-analog conversion unit, generates N constant sine current values through hardware negative feedback, and drives the stepper motor; The current detection unit monitors the current values output by the analog drive unit in real time to fine-tune the output digital signals of the motor control unit; The stepper motor is a two-phase hybrid stepper motor. The analog drive unit includes:

2. A stepper motor drive as claimed in claim 1, characterized in that The A signal conditioning circuit receives analog signal 1 output by the digital-to-analog conversion unit and adjusts the amplitude and polarity of the signal to adapt to the A motor analog drive circuit; The B signal conditioning circuit receives analog signal 2 output by the digital-to-analog conversion unit and adjusts the amplitude and polarity of the signal to adapt to the B motor analog drive circuit; The drive control circuit includes a logic circuit and a signal switch. The drive control circuit receives analog signals output by the A signal conditioning circuit and the B signal conditioning circuit, and according to the control signal output by the motor control unit, the adjusted analog signal A and the analog signal B are sent to the control end of the upper arm transistor of the respective H-bridge through the signal switch, and the corresponding conduction and disconnection of the lower arm of the respective H-bridge are controlled through the logic circuit; The A motor analog drive circuit receives the analog signal processed by the A signal conditioning circuit output by the drive control circuit, and converts it into N constant current signals conforming to the sine law through hardware negative feedback; The B motor analog drive circuit receives the analog signal processed by the B signal conditioning circuit output by the drive control circuit, and converts it into N constant current signals conforming to the cosine law through hardware negative feedback. The analog signals output by the A motor analog drive circuit and the B motor analog drive circuit are 90° out of phase.

3. A stepper motor drive as claimed in claim 2, wherein the drive signal is a pulse width modulated signal. The A motor analog drive circuit and the B motor analog drive circuit each include:

4. A stepper motor drive as claimed in claim 3, wherein the drive signal is a pulse width modulated signal. The left error amplification circuit receives the output signals of the signal conditioning circuit and the left current sampling circuit, and obtains the left given error signal by subtraction; The left gain adjustment circuit receives the left given error signal and adjusts the amplitude, polarity, and rise time of the signal; The left current sampling circuit and the right current sampling circuit sample the current signals output by the H-bridge in real time; The right error amplification circuit receives the output signals of the signal conditioning circuit and the right current sampling circuit, and obtains the right given error signal by subtraction; The right gain adjustment circuit receives the right given error signal and adjusts the amplitude, polarity, and rise time of the signal; The H-bridge circuit receives the error signal output by the gain adjustment circuit and completes the driving of the stepper motor under the logic control of the drive control circuit. ​ 5. A stepper motor drive as claimed in claim 4, wherein the drive signal is a pulse width modulated signal. The left error amplifier circuit and the right error amplifier circuit are subtraction circuits built by using operational amplifiers or transistors, the signal bandwidth of the operational amplifiers or transistors is greater than 10 MHz, the signal gain ratio is greater than 60 dB, and the input bias current is less than 10 nA.

6. A stepper motor drive as claimed in claim 4, wherein the drive signal is a pulse width modulated signal. The left gain adjustment circuit and the right gain adjustment circuit are integral circuits built by using operational amplifiers, the signal bandwidth is greater than 10 MHz, the signal gain ratio is greater than 60 dB, and the input bias current is less than 10 nA.

7. A stepping motor drive apparatus as claimed in claim 4, wherein The left current sampling circuit and the right current sampling circuit are multi-stage differential proportional circuits composed of instrument amplifiers or operational amplifiers, the offset voltage of the instrument amplifiers and the operational amplifiers is not more than 10 μV, the temperature drift voltage is not more than 5 , the input bias current is not more than 100 pA, and the signal bandwidth is greater than 10 MHz.

8. A method of driving control of a stepping motor applied to the stepping motor driving apparatus of claims 1 to 7, characterized by, The method comprises the following steps: S100. The motor control unit establishes a set of digital-to-analog conversion numerical tables according to a sinusoidal function, the numerical table has N items, and each item corresponds to an angle ; S200. The motor control unit calls a numerical table, generates two sets of N-term positive and negative sine function tables with a phase difference of 90°, and sends the digital quantity in the function table to the digital-to-analog conversion unit to be converted into an analog quantity; S300. The analog driving unit generates two positive and negative sine motor driving signals with a phase difference of 90° under the control of the motor control unit, and drives the operation of the stepping motor; S400. During the whole control process, the motor control unit compares the current flowing through the motor winding with the set current through the current detection unit, and adjusts the value of the motor driving signal in real time to ensure the stability and accuracy of the motor winding current.

9. The stepper motor drive control method as described in claim 8, characterized in that, The control method of the analog driving unit further comprises: The period of the A and B routes of the sine signals generated by the digital-analog conversion unit is T, the starting angle of the A route is 0°, the starting angle of the B route is 90°, and the output time of each step is , After the motor is started, the motor control unit extracts the Xth item from two sets of function tables to generate two motor drive given signals with a phase difference of 90°, X represents a specific item in the numerical table, and the initial value is 1, and the devices of the A and B two-way H-bridge are controlled through the drive control circuit The corresponding conduction and shutdown generate a constant drive current, wherein The transistors represent the upper and lower arms of the H-bridge, the timer synchronously counts the current load time, and the Nth data of the digital-analog conversion numerical table is sequentially sent out as a given signal to form a sine current, completing the drive control of the stepper motor in one cycle.

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