Stepping motor driving system based on PWM duty ratio conversion power amplification circuit topology

Abstract

The invention provides a stepping motor driving system based on PWM duty ratio conversion power amplification circuit topology, and relates to the technical field of motor control, the stepping motor driving system comprises an FPGA control circuit, a filter circuit and a differential power amplification circuit which are arranged in sequence, and the FPGA control circuit is used for outputting a PWM waveform for controlling a stepping motor; the filter circuit is used for filtering carrier signals of PWM waveforms and outputting signals only containing modulation waves; and the differential power amplification circuit is used for performing power amplification on sine and cosine waves of the control signal. According to the system, software and hardware resources corresponding to D / A conversion are omitted, and the cost is reduced; an H-bridge driving circuit and a power circuit are omitted, so that harmonic interference is avoided, a hardware circuit is simplified, and the stability, electromagnetic compatibility and reliability of a motor driving system are improved; the current sine degree of the motor is improved, subdivision control over the stepping motor is achieved, and speed adjustment of the stepping motor is achieved by changing the PWM waveform change rate.

Description

Technical Field

[0001] The invention relates to the technical field of motor control, and in particular provides a stepper motor drive system based on a PWM duty ratio conversion power amplifier circuit topology. Background Art

[0002] At present, most motor controls use analog and digital circuits to achieve drive control. D / A chips are needed to achieve reference current output and compare it with the winding current collected by the A / D chip. Motor control is achieved through PI controllers or hysteresis comparators. The above control methods increase the complexity and cost of hardware circuits. The power drive circuit topology of stepper motors is mainly achieved through H-bridge circuits in pulse width modulation.

[0003] The H-bridge-based motor drive system will cause output voltage distortion and introduce fundamental frequency harmonics due to the voltage drop of the power device tube, the switching delay time, and the dead time required to prevent the upper and lower bridge arm power devices from being directly connected. At the same time, the PWM drive method is adopted, which introduces the switching frequency harmonics and its integer multiples, generating electromagnetic interference and affecting the normal operation of other circuits in the motor drive system. In addition, the above-mentioned harmonics increase the motor loss, generate severe heat, and generate torque pulsation, which affects the stability of the motor operation and reduces the reliability of the motor drive system. Summary of the invention

[0004] The purpose of this application is to address the deficiencies of motor control methods in the prior art and to propose a stepper motor drive system based on a PWM duty cycle conversion power amplifier circuit topology. The system has the advantages of simple structure, low manufacturing cost, and high reliability.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: a stepper motor drive system based on PWM duty cycle conversion power amplifier circuit topology, the system includes an FPGA control circuit, a filter circuit, and a differential power amplifier circuit arranged in sequence,

[0006] The FPGA control circuit is used to output a PWM waveform for controlling the stepper motor;

[0007] The filter circuit is used to filter out the carrier signal of the PWM waveform, and the output only contains the modulation wave signal, that is, the sine wave;

[0008] The differential power amplifier circuit is used to amplify the power of the sine and cosine waves of the control signal.

[0009] The stepper motor drive system based on the PWM duty cycle conversion power amplifier circuit topology provided by the present invention also has the following technical features: the FPGA control circuit generates a PWM waveform through a PWM generation module, and the PWM generation module includes a sine wave function table, a sine wave generation module, a triangle wave generation module, a comparator and an IO output module.

[0010] The stepper motor drive system based on the PWM duty cycle conversion power amplifier circuit topology provided by the present invention also has the following technical features: the PWM waveform is a waveform whose duty cycle changes in a sinusoidal trend over time, and after being filtered by the filtering circuit, it is restored to a sinusoidal waveform.

[0011] The stepper motor drive system based on the PWM duty cycle conversion power amplifier circuit topology provided by the present invention also has the following technical features: the filter circuit includes resistors R1 and R2, capacitors C1 and C2 and an operational amplifier U1, wherein the input end of the filter circuit is connected to the resistor R1, and the output end of R1 is respectively connected to the input end of the resistor R2 and the input end of the capacitor C2; the output end of the resistor R2 is connected to the positive input end of the operational amplifier U1 and to the input end of the capacitor C1, and the output end of the capacitor C1 is grounded; the output end of the capacitor C2 is connected to the output end of the operational amplifier U1; and the negative input end of the operational amplifier U1 is connected to the output end of U1.

[0012] The stepper motor drive system based on the PWM duty cycle conversion power amplifier circuit topology provided by the present invention also has the following technical features: the resistor R1 is 7.76KΩ, the resistor R2 is 139KΩ, the capacitor C1 is 510pF, the capacitor C2 is 5.1pF, and the resistor and capacitor accuracy is 1%.

[0013] The stepper motor drive system based on the PWM duty cycle conversion power amplifier circuit topology provided by the present invention also has the following technical features: the differential power amplifier circuit is a bridge topology structure, and the differential power amplifier circuit includes four power amplifiers to achieve voltage and current amplification. Every two power amplifiers form a differential amplifier circuit pair for driving a certain phase of the stepper motor.

[0014] The stepper motor drive system based on the PWM duty cycle conversion power amplifier circuit topology provided by the present invention also has the following technical features: the differential power amplifier circuit includes a resistor R3, a resistor R4, a power operational amplifier U2 and a power operational amplifier U3; one end of the resistor R3 is grounded, and the other end is connected to the negative input end of the power operational amplifier U2 and the resistor R4; the other end of the resistor R4 is connected to the output end of the power operational amplifier U2; the positive input end of the power operational amplifier U2 is connected to the output of the pre-stage filter circuit; one end of the resistor R5 is grounded, and the other end is connected to the negative input end of the power operational amplifier U3 and the resistor R6; the other end of the resistor R6 is connected to the output end of the power operational amplifier U3; the positive input end of the power operational amplifier U3 is connected to the output of the pre-stage filter circuit.

[0015] The stepper motor drive system based on the PWM duty cycle conversion power amplifier circuit topology provided by the present invention also has the following technical features: the resistance values ​​of resistors R3 and R5 are 10KΩ, the resistance values ​​of resistors R4 and R6 are 75KΩ, and the accuracy of resistors R3, R4 and R5 is no more than 1%.

[0016] Beneficial Effects

[0017] The stepper motor drive system based on the PWM duty ratio conversion power amplifier circuit topology provided by the present invention adopts FPGA to directly output the PWM waveform that uses the duty ratio to represent the signal amplitude, thereby eliminating the software and hardware resources corresponding to the D / A conversion and reducing the cost; adopts the power amplifier circuit topology to replace the traditional PWM drive H-bridge structure, eliminating the H-bridge drive circuit and the power circuit, not only avoiding harmonic interference, but also simplifying the hardware circuit, improving the stability, electromagnetic compatibility and reliability of the motor drive system; adopts a high-power operational amplifier to amplify the power of the sine and cosine waves of the control signal, improving the sinusoidality of the motor current, realizing subdivision control of the stepper motor, and realizing the speed regulation of the stepper motor by changing the PWM waveform change rate. This control method can greatly simplify the software design and realize high-precision control. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 The overall structural block diagram of the system provided by the embodiment of the present invention;

[0020] Figure 2 A schematic diagram of the structure of a filter circuit provided by an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of the structure of a differential power amplifier circuit provided by an embodiment of the present invention;

[0022] Figure 4 It is a structural schematic diagram of a PWM generation module provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present application is further described in detail below in conjunction with the accompanying drawings and examples, but it should be noted that these implementation methods are not limitations of the present application, and equivalent changes or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these implementation methods are all within the scope of protection of the present application.

[0024] In the description of the embodiments of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the creation of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the creation of the present application.

[0025] In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0026] The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention of this application can be understood by specific circumstances.

[0027] like Figure 1-4 As shown, the embodiment of the present application provides a stepper motor drive system based on a PWM duty cycle conversion power amplifier circuit topology, the system includes an FPGA control circuit, a filter circuit, and a differential power amplifier circuit arranged in sequence.

[0028] The FPGA control circuit is used to output a PWM waveform for controlling the stepper motor;

[0029] The filter circuit is used to filter out the carrier signal of the PWM waveform, and the output only contains the modulation wave signal, that is, the sine wave;

[0030] The differential power amplifier circuit is used to amplify the power of the sine and cosine waves of the control signal.

[0031] In some embodiments, Figure 4 As shown, the FPGA control circuit generates a PWM waveform through a PWM generation module, and the PWM generation module includes a sine wave function table, a sine wave generation module, a triangle wave generation module, a comparator and an IO output module.

[0032] In some embodiments, the PWM waveform is a waveform whose duty changes in a sinusoidal trend over time, and is restored to a sinusoidal waveform after being filtered by the filtering circuit.

[0033] In some embodiments, the filter circuit includes a second-order Butterworth low-pass filter composed of resistors R1 and R2, capacitors C1 and C2, and an operational amplifier U1, with a cutoff frequency of 3kHz, which has the "flattest" response, while providing the steepest transition between the passband and the stopband and avoiding peaking. The filter passband range is 0 to 3KHz, and the stopband range is above 30KHz.

[0034] The input end of the filter circuit is connected to the resistor R1, and the output end of R1 is connected to the input end of the resistor R2 and the input end of the capacitor C2 respectively; the output end of the resistor R2 is connected to the positive input end of the operational amplifier U1 and the input end of the capacitor C1, and the output end of the capacitor C1 is grounded; the output end of the capacitor C2 is connected to the output end of the operational amplifier U1; the negative input end of the operational amplifier U1 is connected to the output end of U1. The PWM signal sent by the FPGA contains a modulation wave less than 3kHz and a carrier signal greater than 100kHz. After passing through the corresponding filter circuit, the signal greater than 30kHz is filtered out, and the circuit output only contains a modulation wave signal less than 3kHz, that is, a sine wave.

[0035] In some embodiments, the resistor R1 is 7.76KΩ, the resistor R2 is 139KΩ, the capacitor C1 is 510pF, the capacitor C2 is 5.1nF, and the resistor and capacitor accuracy is 1%.

[0036] In some embodiments, the differential power amplifier circuit is a bridge topology structure, and the differential power amplifier circuit includes four power amplifiers to achieve voltage and current amplification, and each two power amplifiers form a differential amplifier circuit pair for driving a certain phase of the stepper motor. A total of two pairs of differential power amplifier circuits realize two-phase stepper motor driving.

[0037] In some embodiments, the differential power amplifier circuit includes a resistor R3, a resistor R4, a power operational amplifier U2 and a power operational amplifier U3, one end of the resistor R3 is grounded, and the other end is connected to the negative input end of the power operational amplifier U2 and the resistor R4, the other end of the resistor R4 is connected to the output end of the power operational amplifier U2, and the positive input end of the power operational amplifier U2 is connected to the output of the pre-stage filter circuit; one end of the resistor R5 is grounded, and the other end is connected to the negative input end of the power operational amplifier U3 and the resistor R6, the other end of the resistor R6 is connected to the output end of the power operational amplifier U3, and the positive input end of the power operational amplifier U3 is connected to the output of the pre-stage filter circuit.

[0038] In some embodiments, the resistance values ​​of the resistors R3 and R5 are 10KΩ, the resistance values ​​of the resistors R4 and R6 are 75KΩ, and the precision of the resistors R3, R4, and R5 is not greater than 1%.

[0039] In some embodiments, Figure 3 As shown in the figure, the differential power amplifier takes phase A as an example. The input terminals of IN1 and IN2 input a biased sinusoidal signal with a voltage range of 0 to 3.3V. By adjusting the resistance values ​​of R3 and R4 and the resistance values ​​of R5 and R6, the biased sinusoidal voltage is amplified from 0 to 3.3V to 0 to 28V. The differential drive structure is adopted, and the drive voltage range of phase A is -28V to 28V. A power amplifier that meets the output current of 5A is selected to achieve the maximum current drive capability of 5A. Phase B is consistent with phase A.

[0040] In the system provided in the above embodiment, the FPGA outputs four PWM waveforms that use duty cycle to represent the signal amplitude, where two PWM signals with a phase difference of π are grouped together, for a total of two groups. The phase difference between the two groups of signals is π / 2; the two groups of PWM waves output are converted into biased sine waves after passing through the filter circuit; the two groups of biased sine waves with a phase difference of π / 2 are passed to the differential power amplifier circuit, which is responsible for differential power amplification of the sine wave of the control signal to increase the current supplied to the stepper motor winding; the two groups of sine waves with large current are input into the two-phase winding of the stepper motor to achieve high-precision subdivision control of the stepper motor.

[0041] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A stepper motor drive system based on PWM duty cycle conversion power amplifier circuit topology, characterized in that: The system includes an FPGA control circuit, a filter circuit, and a differential power amplifier circuit which are arranged in sequence. The FPGA control circuit is used to output a PWM waveform for controlling the stepper motor; The filtering circuit is used to filter out the carrier signal of the PWM waveform, and the output only contains the modulation wave signal; The differential power amplifier circuit is used to amplify the power of the sine and cosine waves of the control signal.

2. The stepper motor drive system based on PWM duty cycle conversion power amplifier circuit topology according to claim 1 is characterized in that: The FPGA control circuit generates a PWM waveform through a PWM generation module, and the PWM generation module includes a sine wave function table, a sine wave generation module, a triangle wave generation module, a comparator and an IO output module.

3. The stepper motor drive system based on PWM duty cycle conversion power amplifier circuit topology according to claim 2 is characterized in that: The PWM waveform is a waveform whose duty changes with time in a sinusoidal trend, and is restored to a sinusoidal waveform after being filtered by the filtering circuit.

4. The stepper motor drive system based on PWM duty cycle conversion power amplifier circuit topology according to claim 1 is characterized in that: The filter circuit includes a resistor R1, a resistor R2, a capacitor C1, a capacitor C2 and an operational amplifier U1, wherein the input end of the filter circuit is connected to the resistor R1, and the output end of R1 is respectively connected to the input end of the resistor R2 and the input end of the capacitor C2; the output end of the resistor R2 is connected to the positive input end of the operational amplifier U1 and to the input end of the capacitor C1, and the output end of the capacitor C1 is grounded; the output end of the capacitor C2 is connected to the output end of the operational amplifier U1; and the negative input end of the operational amplifier U1 is connected to the output end of U1.

5. The stepper motor drive system based on PWM duty cycle conversion power amplifier circuit topology according to claim 4 is characterized in that: The value of the resistor R1 is 7.76KΩ, the value of the resistor R2 is 139KΩ, the value of the capacitor C1 is 510pF, the value of the capacitor C2 is 5.1pF, and the resistance and capacitance precision is 1%.

6. The stepper motor drive system based on PWM duty cycle conversion power amplifier circuit topology according to claim 1, characterized in that: The differential power amplifier circuit is a bridge topology structure. The differential power amplifier circuit includes four power amplifiers to achieve voltage and current amplification. Every two power amplifiers form a differential amplifier circuit pair for driving a certain phase of a stepper motor.

7. The stepper motor drive system based on PWM duty cycle conversion power amplifier circuit topology according to claim 6 is characterized in that: The differential power amplifier circuit includes a resistor R3, a resistor R4, a power operational amplifier U2 and a power operational amplifier U3, wherein one end of the resistor R3 is grounded, and the other end is connected to the negative input end of the power operational amplifier U2 and the resistor R4, the other end of the resistor R4 is connected to the output end of the power operational amplifier U2, and the positive input end of the power operational amplifier U2 is connected to the output of the pre-stage filter circuit; one end of the resistor R5 is grounded, and the other end is connected to the negative input end of the power operational amplifier U3 and the resistor R6, the other end of the resistor R6 is connected to the output end of the power operational amplifier U3, and the positive input end of the power operational amplifier U3 is connected to the output of the pre-stage filter circuit.

8. The stepper motor drive system based on PWM duty cycle conversion power amplifier circuit topology according to claim 7 is characterized in that: The resistance values ​​of the resistors R3 and R5 are 10KΩ, the resistance values ​​of the resistors R4 and R6 are 75KΩ, and the precision of the resistors R3, R4 and R5 is not greater than 1%.

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