Common-mode interference-resistant constant current drive circuit and stepper motor driver

Abstract

This application discloses a constant current drive circuit and a stepper motor driver for common-mode interference suppression, relating to the field of driver technology. The circuit includes: an input module, a first high-frequency filter module, a constant current trigger module, a second high-frequency filter module, and a drive module connected in sequence. The input module receives an input signal, filters it through the first high-frequency filter module, and outputs it to the constant current trigger module. The constant current trigger module converts the filtered input signal into a constant current, generates a drive trigger signal based on the constant current, and outputs it to the drive module after secondary high-frequency common-mode filtering by the second high-frequency filter module. The drive module drives an external device based on the drive trigger signal. By constructing a multi-stage common-mode suppression system using the input module, the first high-frequency filter module, and the second high-frequency filter module, combined with the constant current drive characteristics of the constant current trigger module, hardware-level amplitude suppression and isolation of transient common-mode interference such as EFT are achieved while maintaining pulse response speed, reducing the probability of false triggering.

Description

Technical Field

[0001] This application relates to the field of driver technology, and in particular to constant current drive circuits and stepper motor drivers that are resistant to common-mode interference. Background Technology

[0002] Stepper motors, as core actuators in precision motion control, are widely used in industrial automation, robotics, medical equipment, and other applications requiring high positioning accuracy and reliability. Their drive circuits typically achieve precise control of motor angle and speed by receiving pulse signals from an external controller. The integrity and anti-interference capability of the pulse signals directly determine the stability of the system. However, in electromagnetic compatibility testing (especially electrical fast transient / burst immunity testing, EFT / Burst), the pulse input port of the drive circuit is susceptible to high-frequency transient interference, leading to false triggering or superposition of additional pulses. This can cause problems such as motor positioning deviation, missed steps, or multiple steps, seriously threatening the reliability and safety of the system.

[0003] EFT testing simulates transient high-voltage pulse group interference generated by switching actions and relay on / off states in real-world environments. This interference can intrude into circuits through power lines, signal lines, or spatial coupling. For stepper motor drive circuits, if the signal conditioning circuit at the pulse input port does not employ effective filtering, shielding, or isolation measures, transient interference can couple to the control signal path, causing signal edge distortion or parasitic oscillations. Especially in high-speed pulse mode, interference pulses may be misinterpreted as valid signals, leading to logic mismatch between the controller and the driver. Therefore, improving the EFT interference immunity of the pulse port while ensuring signal transmission efficiency has become a key challenge in the design of high-reliability stepper motor drives. Utility Model Content

[0004] The main objective of this application is to provide a constant current drive circuit and a stepper motor driver that are resistant to common-mode interference, aiming to solve the technical problem of poor EFT interference resistance of the pulse port of the existing stepper motor drive circuit.

[0005] To achieve the above objectives, this application proposes a constant current drive circuit for resisting common-mode interference, which includes: an input module, a first high-frequency filter module, a constant current trigger module, a second high-frequency filter module, and a drive module connected in sequence.

[0006] The input module is used to receive an input signal and output the input signal to the constant current trigger module after filtering it through the first high-frequency filtering module.

[0007] The constant current trigger module is used to convert the filtered input signal into a constant current;

[0008] The constant current trigger module is also used to generate a drive trigger signal based on the constant current, and output the drive trigger signal to the drive module after passing it through the second high frequency filter module for secondary high frequency common mode filtering;

[0009] The drive module is used to drive external devices to work based on the drive trigger signal.

[0010] In one embodiment, the input module includes: a first resistor and a first inductor; the second end of the first inductor is electrically connected to the first end of the first high-frequency filter module; the first end and the second end of the first resistor are respectively electrically connected to the second end and the third end of the first high-frequency filter module.

[0011] In one embodiment, the input module further includes: a first diode; the cathode of the first diode is electrically connected to a first terminal of the first inductor.

[0012] In one embodiment, the constant current trigger module includes: a second resistor, a third resistor, a first transistor, a second transistor, and an optocoupler; a first terminal of the second resistor is electrically connected to a first terminal of the optocoupler and a first terminal of the first resistor; a second terminal of the second resistor is electrically connected to the base of the first transistor and the collector of the second transistor; a second terminal of the optocoupler is electrically connected to the driving module through a second high-frequency filter module; a third terminal of the optocoupler is grounded through the second high-frequency filter module; the collector of the first transistor is electrically connected to a fourth terminal of the optocoupler, and the emitter of the first transistor is electrically connected to the base of the second transistor and a first terminal of the third resistor; a second terminal of the third resistor is electrically connected to the emitter of the second transistor and a second terminal of the first resistor.

[0013] In one embodiment, the constant current trigger module further includes: a fourth resistor; a first end of the fourth resistor is electrically connected to the fourth end of the optocoupler; and a second end of the fourth resistor is electrically connected to the emitter of the first transistor.

[0014] In one embodiment, the driving module includes: a fifth resistor; a first end of the fifth resistor is electrically connected to a power supply; and a second end of the fifth resistor is electrically connected to a second end of the optocoupler.

[0015] In one embodiment, the driving module further includes: a sixth resistor and a first capacitor; a first terminal of the sixth resistor is electrically connected to a second terminal of the fifth resistor; a second terminal of the sixth resistor is electrically connected to a first terminal of the first capacitor, and a second terminal of the first capacitor is grounded.

[0016] In one embodiment, the first high-frequency filtering module includes: a first common-mode inductor; a first terminal of the first common-mode inductor electrically connected to a second terminal of the first inductor; a second terminal of the first common-mode inductor electrically connected to a first terminal of the first resistor; and a third terminal of the first common-mode inductor electrically connected to a second terminal of the first resistor.

[0017] In one embodiment, the second high-frequency filtering module includes: a second common-mode inductor; a first terminal of the second common-mode inductor electrically connected to a second terminal of the optocoupler; a second terminal of the second common-mode inductor electrically connected to a second terminal of the fifth resistor; a third terminal of the second common-mode inductor grounded; and a fourth terminal of the second common-mode inductor electrically connected to a third terminal of the optocoupler.

[0018] In addition, to achieve the above objectives, this application also proposes a stepper motor driver that uses the common-mode interference-resistant constant current drive circuit as described above.

[0019] One or more technical solutions proposed in this application have at least the following technical effects:

[0020] In the input module, a high-frequency impedance path is formed by the combination of a first resistor and a first inductor. Combined with a first high-frequency filter module consisting of a first common-mode inductor, this effectively filters out high-frequency common-mode noise coupled to the input signal line and suppresses the distortion effect of transient interference on the pulse edge. The constant-current trigger module, through a cascaded structure of an optocoupler and a transistor, converts the filtered pulse signal into a constant-current drive signal. The constant-current characteristic clamps the amplitude of residual interference pulses, preventing parasitic oscillations from being misinterpreted as valid signals. Simultaneously, the second high-frequency filter module further blocks the transmission of interference to the drive module by performing secondary common-mode filtering at the optocoupler output. Compared to the shortcomings of existing technologies that rely on RC filtering, leading to pulse delay or software debouncing sacrificing real-time performance, this solution uses a multi-stage common-mode suppression system comprised of the input module, the first high-frequency filter module, and the second high-frequency filter module. Combined with the constant-current drive characteristic of the constant-current trigger module, it maintains the pulse response speed while achieving hardware-level amplitude suppression and isolation of transient common-mode interference such as EFT, reducing the probability of false triggering. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A structural block diagram provided for an embodiment of the constant current drive circuit for common-mode interference suppression in this application;

[0024] Figure 2 The circuit connection diagram is provided for a specific implementation of the constant current drive circuit for common-mode interference suppression in this application.

[0025] Explanation of icon numbers:

[0026] 10. Input module; 20. First high-frequency filter module; 30. Constant current trigger module; 40. Drive module; 50. Second high-frequency filter module; R1. First resistor; L1. First inductor; D1. First diode; R2. Second resistor; R3. Third resistor; Q1. First transistor; Q2. Second transistor;

[0027] U1, optocoupler; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; C1, first capacitor; GL1, first common-mode inductor; GL2, second common-mode inductor.

[0028] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0030] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0031] Existing solutions are mostly based on hardware filtering (such as RC circuits filtering high-frequency noise through capacitor charging and discharging, or ferrite beads attenuating interference using high-frequency impedance characteristics) and software debouncing algorithms (filtering jitter signals through logic judgment). However, in hardware filtering schemes, the time constant of the RC circuit will delay the rising / falling edge of the pulse signal, resulting in a delay in the transmission of effective pulses, while the high-frequency attenuation characteristics of ferrite beads may weaken the steepness of the signal edge. Both of these will reduce the pulse response speed and affect the timing accuracy in high-speed motion control scenarios. Although software debouncing algorithms can filter interference pulses through time windows, they rely on the delay judgment mechanism of the microcontroller. In high-speed pulse sequences (such as microsecond-level step control) or industrial applications with strict real-time requirements, they are prone to missed or false judgments due to the overlap between the algorithm processing cycle and the width of the interference pulse, and cannot meet the dual requirements of anti-interference and real-time response.

[0032] Based on this, this application proposes an embodiment of a constant current drive circuit that resists common-mode interference. Please refer to [link / reference]. Figure 1 , Figure 1This is a structural block diagram of a constant current drive circuit embodiment for common-mode interference suppression in this application.

[0033] In this embodiment, the constant current drive circuit for resisting common-mode interference includes: an input module 10, a first high-frequency filter module 20, a constant current trigger module 30, and a drive module 40 connected in sequence.

[0034] It should be noted that the input module 10 is used to receive the input signal and output the input signal to the constant current trigger module 30 after filtering by the first high-frequency filter module 20.

[0035] Understandably, input module 10 needs to be capable of receiving various types of input signals. In practical applications, input signals may come from different sources, such as analog signals output by sensors or digital signals generated by digital controllers. This module should be able to adapt to inputs with different level standards (such as TTL level and CMOS level) and different signal formats (such as PWM signals and pulse sequence signals), ensuring that the external signal can be accurately received regardless of its form.

[0036] Understandably, when transmitting the received signal to the first high-frequency filtering module 20, it is important to minimize signal loss during transmission. This can be achieved by optimizing the impedance matching of the signal transmission path, such as by selecting a suitable transmission line type (coaxial cable, twisted pair, etc.) to match the characteristic impedance of the transmission line with the input impedance of the input module 10 and the first high-frequency filtering module 20. This reduces signal reflection and energy loss, ensuring that the signal reaches the filtering module with high quality.

[0037] Understandably, it's crucial to prevent external interference from affecting the signal during transmission. Shielding measures can be employed, such as using shielded transmission lines, to block external electromagnetic interference. Simultaneously, a proper layout of signal lines on the circuit board is essential to avoid mutual interference and ensure the signal is unaffected by external noise during transmission, providing a solid foundation for subsequent filtering.

[0038] Understandably, high-frequency noise in electronic systems can originate from multiple sources. For example, switching devices in a power supply generate high-frequency electromagnetic interference (EMI) during the switching process, which can couple into the input signal through the power line; external electromagnetic radiation, such as radio signals and lightning, can also induce high-frequency noise on signal transmission lines.

[0039] Understandably, the first high-frequency filtering module 20 can effectively remove these high-frequency noises from the input signal. Assume the input signal is an effective signal with frequency f0, mixed with multiple high-frequency noise signals with frequencies f1, f2, etc. After passing through the high-frequency filtering module, the amplitude of the high-frequency noise signals will be significantly attenuated, while the effective signal f0 is almost unaffected, thus providing a relatively clean signal for the subsequent constant current triggering module 30.

[0040] It should be noted that the constant current trigger module 30 is used to convert the filtered input signal into a constant current. The constant current trigger module 30 is also used to generate a drive trigger signal based on the constant current and output the drive trigger signal to the drive module 40.

[0041] It should be noted that the constant current trigger module 30 typically utilizes electronic components or circuit structures with constant current characteristics to convert signals into constant current. For example, a constant current source circuit using transistors can be employed. The emitter-base voltage of a transistor remains relatively stable within a certain range. By appropriately designing circuit parameters, such as the base bias resistor and emitter resistor, the collector current can be kept relatively constant. After the input signal passes through the first high-frequency filter module 20, it is input to the control terminal of the constant current trigger module 30. By adjusting the operating state of the transistor, the changes in the input signal are converted into a constant collector current output.

[0042] Understandably, dedicated integrated constant current chips can also be used. These chips integrate precise constant current control circuitry, requiring only a few external resistors, capacitors, and other components to generate a stable constant current based on the input signal. Integrated constant current chips offer advantages such as high precision, good stability, and simple design, significantly simplifying the design process of the constant current trigger module 30. For example, in a 5-24V compatible input drive circuit, the input voltage may fluctuate. The constant current is unaffected by small fluctuations in the input voltage, maintaining a stable current output value. For instance, when the input voltage increases from 5V to 24V, the magnitude of the constant current remains essentially unchanged, providing stable operating conditions for the subsequent drive module 40 and avoiding drive instability issues caused by current variations.

[0043] It should be noted that the drive trigger signal is a key instruction for the operation of the drive module 40, which can accurately control the timing and mode of the drive module 40's actions. For example, in a stepper motor drive system, the drive trigger signal can control the number of steps and the direction of rotation of the stepper motor. After the constant current trigger module 30 generates the corresponding drive trigger signal based on the input signal, the drive module 40 receives the signal and drives the stepper motor to rotate according to the preset logic, thereby achieving precise position control.

[0044] Understandably, the drive trigger signal can also be used to achieve status feedback and coordinated operation between the drive module 40 and other modules. For example, after receiving the drive trigger signal, the drive module 40 starts working and can return its own working status (such as whether it is overloaded or whether it has completed the action) to the constant current trigger module 30 or other control modules through feedback signals so that the system can make corresponding adjustments and optimizations.

[0045] Understandably, the constant current trigger module 30 can internally incorporate a current comparator to compare the converted constant current with a preset reference current. When the constant current reaches or exceeds the reference current, the comparator outputs a specific level signal (such as a high level) as part of the drive trigger signal. For example, in a circuit requiring precise control of the drive module 40's operation, the preset reference current corresponds to the drive module 40's start-up threshold. When the constant current reaches this threshold, the comparator outputs a high-level signal, triggering the drive module 40 to begin operation.

[0046] Understandably, a drive trigger signal can be generated by detecting changes in a constant current. A current change detection circuit can be set up; when the constant current undergoes a specific change within a short period (e.g., the rising or falling edge reaches a certain slope), the detection circuit generates a pulse signal as the drive trigger signal. This generation method is suitable for scenarios where the operation of the drive module 40 needs to be controlled based on dynamic changes in the current.

[0047] In this embodiment, by employing a first high-frequency filtering module with a specific structure (which performs high-frequency filtering on the input signal to remove high-frequency noise components such as EFT interference) and a constant current trigger module (which converts the filtered signal into a constant current and generates a stable drive trigger signal) in the stepper motor drive circuit, the problem of poor EFT interference resistance at the pulse port of the existing stepper motor drive circuit is solved. Compared with the prior art, the first high-frequency filtering module effectively blocks EFT interference signals from entering subsequent circuits, preventing them from causing signal abnormalities; the constant current trigger module generates the drive trigger signal based on a constant current, unaffected by voltage fluctuations caused by EFT interference, thereby providing a stable and reliable signal for the drive module, significantly enhancing the EFT interference resistance of the stepper motor drive circuit pulse port, and ensuring the stability and accuracy of the stepper motor drive.

[0048] Furthermore, based on the above embodiments, this application provides specific implementation methods, please refer to... Figure 2 , Figure 2 The circuit connection diagram is provided for a specific implementation of the constant current drive circuit for common-mode interference suppression in this application.

[0049] In this embodiment, the input module 10 includes: a first resistor R1 and a first inductor L1; the second end of the first inductor L1 is electrically connected to the first end of the first high-frequency filter module 20; the first end and the second end of the first resistor R1 are electrically connected to the second end and the third end of the first high-frequency filter module 20, respectively.

[0050] In addition, the input module 10 also includes: a first diode D1; the cathode of the first diode D1 is electrically connected to the first terminal of the first inductor L1.

[0051] It should be noted that the positive input terminal of the input module 10 is the anode of the first diode D1, and the negative input terminal of the input module 10 is the fourth terminal of the first high-frequency filter module 20.

[0052] Understandably, the first inductor L1 has the characteristic of passing DC and blocking AC. In a circuit, when common-mode interference exists in the input signal, the common-mode interference signal is usually a high-frequency AC signal. The first inductor L1 will generate a large inductive reactance to the high-frequency common-mode interference signal, hindering its passage.

[0053] Understandably, the first resistor R1 can dissipate the energy accumulated by the differential-mode signal, and also helps to dissipate some of the energy of the common-mode interference signal. When the common-mode interference signal enters the input module 10, the first resistor R1 will share the energy of the interference signal with other components in the circuit, and limit the voltage magnitude of the interference signal to prevent the interference signal from causing excessive impact on subsequent circuits.

[0054] Understandably, the first diode D1 has unidirectional conductivity, which is used to prevent incorrect input polarity connection and to improve resistance to reverse spike interference, which could damage the constant current circuit.

[0055] In this embodiment, the constant current trigger module 30 includes: a second resistor R2, a third resistor R3, a first transistor Q1, a second transistor Q2, and an optocoupler U1. The first end of the second resistor R2 is electrically connected to the first end of the optocoupler U1 and the first end of the first resistor R1; the second end of the second resistor R2 is electrically connected to the base of the first transistor and the collector of the second transistor Q2; the second end of the optocoupler U1 is electrically connected to the drive module 40 through a second high-frequency filter module; the third end of the optocoupler U1 is grounded through the second high-frequency filter module; the collector of the first transistor is electrically connected to the fourth end of the optocoupler U1, and the emitter of the first transistor is electrically connected to the base of the second transistor Q2 and the first end of the third resistor R3; the second end of the third resistor R3 is electrically connected to the emitter of the second transistor Q2 and the second end of the first resistor R1.

[0056] It should be noted that the optocoupler U1 provides electrical isolation, separating the input signal from the output drive signal. This effectively prevents interference signals from the input terminal from being directly transmitted to the output terminal, while also preventing the output signal from affecting the input terminal. Furthermore, it can control the on / off state of the output terminal based on the input signal, providing trigger signals for subsequent drive modules.

[0057] Understandably, in the circuit, the base current of the first transistor Q1 is controlled by the second resistor R2 and the input signal. When the input signal changes, the base current of the first transistor Q1 changes, and its collector current also changes accordingly. Since the collector of the first transistor Q1 is electrically connected to the base of the second transistor Q2, the base current of the second transistor Q2 changes accordingly, causing a change in the collector current (i.e., the output current) of the second transistor Q2. By adjusting the resistance values ​​of the second resistor R2 and the third resistor R3, and by appropriately selecting the transistor parameters, the output current can be kept essentially constant within a certain range. This is because when the output current attempts to increase, it causes a change in the base-emitter voltage of the second transistor Q2, which, through feedback, suppresses further increases in the output current, and vice versa, thus achieving constant current control.

[0058] The second resistor R2 serves to limit current and divide voltage, restricting the current flowing into the base of the first transistor Q1 to prevent excessive current from damaging the transistor. It also works with the input signal to determine the base voltage of the first transistor Q1. The third resistor R3 is the emitter resistor of the second transistor Q2, and it participates in constant current control through a negative feedback mechanism.

[0059] In addition, the constant current trigger module 30 also includes: a fourth resistor R4; the first end of the fourth resistor R4 is electrically connected to the fourth end of the optocoupler U1; and the second end of the fourth resistor R4 is electrically connected to the emitter of the first transistor.

[0060] Understandably, the fourth resistor R4 shunts the current of the first transistor Q1, ensuring a proper distribution of the current entering the base and collector-emitter current of Q1. During circuit operation, not all the current output by the optocoupler U1 flows into the first transistor Q1; a portion is shunted through the fourth resistor R4. This shunting effect prevents the first transistor Q1 from entering the saturation region due to excessive current, ensuring it operates within the appropriate linear amplification region, thus contributing to a stable constant current output.

[0061] In this embodiment, the driving module 40 includes: a fifth resistor R5; the first end of the fifth resistor R5 is electrically connected to the operating power supply; and the second end of the fifth resistor R5 is electrically connected to the third end of the optocoupler U1.

[0062] In addition, the drive module 40 also includes: a sixth resistor R6 and a first capacitor C1; the first end of the sixth resistor R6 is electrically connected to the second end of the fifth resistor R5; the second end of the sixth resistor R6 is electrically connected to the first end of the first capacitor C1, and the second end of the first capacitor C1 is grounded.

[0063] Understandably, when optocoupler U1 does not receive a constant current control signal, its second and third terminals are disconnected. At this time, the fifth resistor R5 pulls the third terminal of optocoupler U1 (i.e., the input terminal of drive module 40) up to the operating power supply voltage, ensuring that this terminal is in a stable high-level state. When a constant current control signal is received, the second and third terminals of optocoupler U1 are connected to ground, and the second terminal of the fifth resistor R5 is grounded. At this time, the level of the third terminal of optocoupler U1 is pulled low (close to ground potential). This high-low level transition clearly indicates the presence or absence of the constant current control signal, providing a reliable signal input for subsequent circuits. The sixth resistor R6 and the first capacitor C1 form an RC filter circuit, mainly used to filter out high-frequency interference signals in the circuit.

[0064] In this embodiment, the first high-frequency filtering module 20 includes: a first common-mode inductor GL1; a first terminal of the first common-mode inductor GL1 is electrically connected to a second terminal of the first inductor L1; a second terminal of the first common-mode inductor GL1 is electrically connected to a first terminal of the first resistor R1; and a third terminal of the first common-mode inductor GL1 is electrically connected to a second terminal of the first resistor R1. The fourth terminal of the first common-mode inductor GL1 serves as the negative input terminal of the input module 10.

[0065] In addition, the constant current drive circuit for common-mode interference suppression also includes: a second high-frequency filter module 50; the second high-frequency filter module 50 includes: a second common-mode inductor GL2; the first end of the second common-mode inductor GL2 is electrically connected to the second end of the optocoupler U1; the second end of the second common-mode inductor GL2 is electrically connected to the second end of the fifth resistor R5; the third end of the second common-mode inductor GL2 is grounded; the fourth end of the second common-mode inductor GL2 is electrically connected to the third end of the optocoupler U1.

[0066] Understandably, the first common-mode inductor GL1 is primarily used to suppress common-mode interference in the input signal. Common-mode interference refers to interference signals of the same phase and amplitude that exist between the signal line and the ground line; it may originate from power lines, external electromagnetic radiation, etc.

[0067] Understandably, the first common-mode inductor GL1 consists of two coils wound in the same direction. When a common-mode interference signal enters the first common-mode inductor GL1, because the currents in the two coils are in the same direction, according to the principle of electromagnetic induction, the magnetic fluxes they generate are superimposed, causing the inductor to exhibit a large inductive reactance XL = 2πfL (where f is the frequency of the interference signal and L is the inductance of a single coil of the common-mode inductor). This large inductive reactance hinders the passage of the common-mode interference signal, thereby attenuating it and reducing its impact on subsequent circuits. For example, in industrial environments, there are numerous sources of electromagnetic interference, such as motors and frequency converters, whose common-mode interference may couple onto the input signal lines. The first common-mode inductor GL1 can effectively filter out this common-mode interference, ensuring the quality of the input signal and providing a stable input for subsequent circuits.

[0068] Understandably, the second common-mode inductor GL2 is electrically connected in the relevant circuit of the optocoupler U1, mainly to suppress common-mode interference in this part of the circuit. The optocoupler U1 plays a role in signal isolation and transmission in the circuit, but its operation is also susceptible to common-mode interference.

[0069] Understandably, in a circuit, the signal transmission between the second and third terminals of optocoupler U1 may be affected by common-mode interference, leading to signal distortion or false triggering. The second common-mode inductor GL2, through its common-mode rejection characteristics, can reduce the impact of common-mode interference signals on the operation of optocoupler U1. When common-mode interference signals enter the second common-mode inductor GL2, they are also subject to its common-mode rejection effect, thereby reducing interference with the normal operation of optocoupler U1. For example, in a stepper motor drive circuit, common-mode interference may cause fluctuations in the output signal of optocoupler U1, affecting the control accuracy of the drive module 40 on the motor; the second common-mode inductor GL2 can effectively prevent this from happening.

[0070] In this embodiment, to address the pulse delay problem caused by hardware filtering, a combined design of a first inductor and a first high-frequency filtering module (common-mode inductor) in the input module is adopted. While filtering out high-frequency common-mode noise, the inductor's rapid suppression of transient interference avoids the time constant introduced by the capacitor charging and discharging process in traditional RC filtering, thus maintaining the steepness of the pulse edge. To address the real-time limitations of software debouncing, the constant-current trigger module uses a cascaded structure of an optocoupler and a transistor to convert the pulse signal into a constant-current drive signal. The output impedance characteristics of the current source are used to dynamically clamp the amplitude of residual interference pulses, directly blocking the accumulation of parasitic oscillation amplitude. Hardware-level amplitude suppression of interference pulses can be achieved without relying on software delay judgment. Furthermore, the second high-frequency filtering module performs secondary common-mode filtering at the optocoupler output, further isolating the transmission path of interference to the drive module, forming a multi-level collaborative common-mode noise suppression mechanism. Compared to existing technologies, this solution simultaneously achieves rapid dissipation of interference energy and active maintenance of signal integrity at the hardware level, balancing anti-interference capability and real-time requirements. While maintaining pulse response speed, hardware-level isolation and amplitude suppression of EFT pulse groups were achieved, thereby significantly reducing the probability of false triggering.

[0071] In addition, to achieve the above objectives, this application also provides a stepper motor driver that uses the common-mode interference-resistant constant current drive circuit described above.

[0072] The stepper motor driver provided in this application employs the common-mode interference-resistant constant current drive circuit described in the above embodiments, which solves the technical problem of poor EFT interference immunity of the pulse port in existing stepper motor drive circuits. Compared with the prior art, the beneficial effects of the stepper motor driver provided in this application are the same as those of the common-mode interference-resistant constant current drive circuit provided in the above embodiments, and other technical features in the stepper motor driver are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0073] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A common-mode interference resistant constant current drive circuit, characterized by comprising: The constant current drive circuit for resisting common-mode interference includes: an input module, a first high-frequency filter module, a constant current trigger module, a second high-frequency filter module, and a drive module connected in sequence. The input module is used to receive an input signal and output the input signal to the constant current trigger module after filtering it through the first high-frequency filtering module. The constant current trigger module is used to convert the filtered input signal into a constant current; The constant current trigger module is also used to generate a drive trigger signal based on the constant current, and output the drive trigger signal to the drive module after passing it through the second high frequency filter module for secondary high frequency common mode filtering; The drive module is used to drive external devices to work based on the drive trigger signal.

2. The common mode rejection constant current driving circuit according to claim 1, wherein The input module includes: a first resistor and a first inductor; The second terminal of the first inductor is electrically connected to the first terminal of the first high-frequency filter module; The first and second ends of the first resistor are electrically connected to the second and third ends of the first high-frequency filter module, respectively.

3. The common-mode rejection constant current driving circuit according to claim 2, wherein The input module further includes: a first diode; the cathode of the first diode is electrically connected to the first terminal of the first inductor.

4. The common-mode rejection constant current driving circuit according to claim 3, wherein The constant current trigger module includes: a second resistor, a third resistor, a first transistor, a second transistor, and an optocoupler; The first end of the second resistor is electrically connected to the first end of the optocoupler and the first end of the first resistor; the second end of the second resistor is electrically connected to the base of the first transistor and the collector of the second transistor. The second end of the optocoupler is electrically connected to the drive module through the second high-frequency filter module; the third end of the optocoupler is grounded through the second high-frequency filter module. The collector of the first transistor is electrically connected to the fourth terminal of the optocoupler, and the emitter of the first transistor is electrically connected to the base of the second transistor and the first terminal of the third resistor. The second end of the third resistor is electrically connected to the emitter of the second transistor and the second end of the first resistor.

5. The common-mode rejection constant current driving circuit according to claim 4, wherein The constant current triggering module further includes: a fourth resistor; The first end of the fourth resistor is electrically connected to the fourth end of the optocoupler; The second end of the fourth resistor is electrically connected to the emitter of the first transistor.

6. The common-mode rejection constant current driving circuit according to claim 5, wherein The driving module includes: a fifth resistor; The first end of the fifth resistor is electrically connected to the operating power supply. The second end of the fifth resistor is electrically connected to the second end of the optocoupler.

7. The common mode rejection constant current driver circuit of claim 6, wherein, The driving module further includes: a sixth resistor and a first capacitor; The first end of the sixth resistor is electrically connected to the second end of the fifth resistor; The second end of the sixth resistor is electrically connected to the first end of the first capacitor, and the second end of the first capacitor is grounded.

8. The common mode rejection constant current driver circuit of claim 7, wherein, The first high-frequency filtering module includes: a first common-mode inductor; The first terminal of the first common-mode inductor is electrically connected to the second terminal of the first inductor; The second terminal of the first common-mode inductor is electrically connected to the first terminal of the first resistor; The third terminal of the first common-mode inductor is electrically connected to the second terminal of the first resistor.

9. The common mode rejection constant current driver circuit of claim 8, wherein, The second high-frequency filtering module includes: a second common-mode inductor; The first terminal of the second common-mode inductor is electrically connected to the second terminal of the optocoupler; The second terminal of the second common-mode inductor is electrically connected to the second terminal of the fifth resistor; The third terminal of the second common-mode inductor is grounded; The fourth terminal of the second common-mode inductor is electrically connected to the third terminal of the optocoupler.

10. A stepping motor driver characterized by comprising: The stepper motor driver uses a constant current drive circuit that resists common-mode interference as described in any one of claims 1 to 9.

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