A differential driving method and an optical coupling isolation system resistant to common mode noise interference

Abstract

The application relates to the technical field of electronic circuits, and discloses a differential driving method resisting common-mode noise interference and an optical coupling isolation system.The differential driving method comprises the following steps: inputting a reference driving signal representing a target conduction state into a same-phase device and an inverse-phase device respectively, generating a first differential signal through the same-phase device, and generating a second differential signal through the inverse-phase device, wherein the first differential signal and the second differential signal have equal amplitudes and opposite phases; generating a differential voltage according to the first differential signal and the second differential signal, and inputting the differential voltage into an optical coupling through anodes and cathodes of light-emitting diodes of the optical coupling, so that the optical coupling is controlled to be in the target conduction state according to a voltage difference between the anodes and the cathodes of the light-emitting diodes.The application can drive the light-emitting diodes of the optical coupling while effectively canceling common-mode noise, and improves the anti-interference capability of an optical coupling driving circuit.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, specifically to a differential driving method and optocoupler isolation system for resisting common-mode noise interference. Background Technology

[0002] In power electronic conversion systems, the drive circuits for power devices (such as IGBTs and MOSFETs) are crucial for ensuring the safe and efficient operation of the system. Especially in high-power applications such as photovoltaic inverters and motor drivers, optocoupler drive circuits are widely used to achieve electrical isolation between the control and power sides.

[0003] Traditional single-ended optocoupler drive circuits are simple in structure and low in cost. Their working principle is to achieve signal isolation transmission through the light-emitting diode and phototransistor inside the optocoupler. However, with the increase in the power level of photovoltaic systems and the increasing complexity of installation environments, such traditional circuits have exposed significant shortcomings in anti-interference.

[0004] Specifically, devices such as photovoltaic inverters typically involve long cable connections, which not only increases parasitic inductance and capacitance but also provides a coupling path for common-mode noise. During the high-frequency switching of power devices, extremely high levels of interference are generated. This strong common-mode noise can couple into the drive signal circuit through the distributed parameters of the long cables. Because traditional single-ended drive circuits rely solely on a single signal line and a reference ground for logic judgment, they lack the ability to suppress signal interference, easily leading to distortion of the drive signal waveform. Summary of the Invention

[0005] This invention provides a differential driving method and optocoupler isolation system for resisting common-mode noise interference, which can drive optocoupler light-emitting diodes while effectively canceling common-mode noise and improving the anti-interference capability of optocoupler driving circuit.

[0006] This invention provides a differential driving method for resisting common-mode noise interference, the method comprising: A reference drive signal characterizing the target conduction state is input to an inverter and an inverter, respectively. A first differential signal is generated by the inverter, and a second differential signal is generated by the inverter. The first differential signal and the second differential signal have the same amplitude and opposite phase. A differential voltage is generated based on the first differential signal and the second differential signal and input to the optocoupler through the positive and negative terminals of the light-emitting diode of the optocoupler, so as to control the optocoupler to be in the target conduction state according to the voltage difference between the positive and negative terminals of the light-emitting diode.

[0007] Optionally, the differential driving method for resisting common-mode noise interference further includes: Obtain the original modulated pulse signal; In response to the rising edge of the original modulated pulse signal, a first delay timer is started, and a high level is output when the first delay timer ends; In response to the falling edge of the original modulation pulse signal, a second delay timer is started, and a low level is output when the second delay timer ends; The high level and the low level are logically ANDed to eliminate the intermediate uncertainty generated during the delay transition of the original modulation pulse signal, and the waveform-processed reference drive signal is output.

[0008] The present invention also provides an optically coupled isolation system for resisting common-mode noise interference, the system comprising an optically coupled isolation unit and a signal conditioning unit for implementing the differential driving method for resisting common-mode noise interference as described in claim 1; The optical coupling isolation unit includes a primary-side light-emitting device and a secondary-side photosensitive device; The first and second output terminals of the signal conditioning unit are connected to the positive and negative terminals of the primary-side light-emitting device, respectively, to convert the first differential signal and the second differential signal into voltage difference signals applied to the positive and negative terminals of the primary-side light-emitting device, so as to control the conduction state of the primary-side light-emitting device and the switching state of the secondary-side photosensitive device.

[0009] Optionally, the signal conditioning unit includes a signal processing module and a signal conversion module; The signal processing module includes an inverting unit and an inverter; The inverting unit is used to convert the reference driving signal into a first differential signal that is in phase with the reference driving signal; The inverter is used to convert the reference drive signal into a second differential signal that is inverted by the reference drive signal; The signal conversion module includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. It is used to input the first differential signal through the first input terminal, input the second differential signal through the second input terminal, and convert the first differential signal and the second differential signal into differential voltages and output them through the first output terminal and the second output terminal of the signal conversion module. The first output terminal and the second output terminal of the signal conversion module correspond to the first output terminal and the second output terminal of the signal conditioning unit.

[0010] Optionally, the signal conversion module includes a first resistor assembly, a second resistor assembly, and a third resistor assembly; One end of the first resistor component serves as the first input terminal of the signal conversion module, and the other end of the first resistor component serves as the first output terminal of the signal conversion module. One end of the second resistor component serves as the second input terminal of the signal conversion module, and the other end of the second resistor component serves as the second output terminal of the signal conversion module; One end of the third resistor assembly is connected to the other end of the first resistor assembly, and the other end of the third resistor assembly is connected to the other end of the second resistor assembly.

[0011] Optionally, the first resistor assembly includes a first resistor, the second resistor assembly includes a second resistor, and the third resistor assembly includes a third resistor, a fourth resistor, and a first capacitor; One end of the first resistor serves as the first input terminal of the signal conversion module, and the other end of the first resistor serves as the first output terminal of the signal conversion module. One end of the second resistor serves as the second input terminal of the signal conversion module, and the other end of the fourth resistor serves as the second output terminal of the signal conversion module. One end of the third resistor is connected to one end of the first resistor, and the other end of the third resistor is connected to one end of the second resistor; One end of the fourth resistor is connected to the other end of the first resistor, and the other end of the fourth resistor is connected to the other end of the second resistor; The first capacitor is connected in parallel with the second resistor and the third resistor.

[0012] Optionally, the signal conditioning unit further includes a delay module for: Obtain the original modulated pulse signal; In response to the rising edge of the original modulated pulse signal, a first delay timer is started, and a high level is output when the first delay timer ends; In response to the falling edge of the original modulation pulse signal, a second delay timer is started, and a low level is output when the second delay timer ends; The high level and the low level are logically ANDed to eliminate the intermediate uncertainty generated during the delay transition of the original modulation pulse signal, and the waveform-processed reference drive signal is output.

[0013] Optionally, the delay module includes a steady-state trigger submodule, which includes a dual-channel monostable trigger, a first adjustable RC component, and a second adjustable RC component. The signal input terminal of the dual-channel monostable multivibrator serves as the input terminal of the delay module, and the output terminal of the dual-channel monostable multivibrator serves as the output terminal of the delay module. The first adjustable resistor-capacitor assembly is connected to the first timing signal terminal of the dual-channel monostable multivibrator; the first adjustable resistor-capacitor assembly includes a first resistor and a first capacitor, one end of the first resistor is connected to the first timing pin of the dual-channel monostable multivibrator, the other end of the first resistor is connected to the positive terminal of the power supply, one end of the first capacitor is connected to the common terminal of the first resistor and the first timing pin, and the other end of the first capacitor is grounded. The second adjustable resistor-capacitor assembly is connected to the second timing signal terminal of the dual-channel monostable multivibrator; the second adjustable resistor-capacitor assembly includes a second resistor and a second capacitor, one end of the second resistor is connected to the second timing pin of the dual-channel monostable multivibrator, the other end of the second resistor is connected to the positive terminal of the power supply, one end of the second capacitor is connected to the common terminal of the second resistor and the second timing pin, and the other end of the second capacitor is grounded.

[0014] Optionally, the steady-state trigger submodule further includes a third resistor, a fourth resistor, a third capacitor, and a fourth capacitor; One end of the third resistor is connected to the second output pin of the dual-channel monostable multivibrator via the third capacitor, and the other end of the third resistor is used to connect to the power supply. One end of the fourth resistor is connected to the first output pin of the dual-channel monostable multivibrator via the fourth capacitor, and the other end of the fourth resistor is used to connect to the power supply.

[0015] Optionally, the optocoupler isolation system for resisting common-mode noise interference further includes a secondary-side power supply purification unit. The secondary-side power supply purification unit is connected in series in the power supply circuit of the secondary-side photosensitive device of the optocoupler isolation unit. It is used to suppress the high-frequency differential-mode ripple of power circuit ground bounce noise conducted to the power supply circuit, so that the driving voltage amplitude provided by the secondary-side photosensitive device to the gate of the power electronic switching device during the output high level is within a preset voltage value range.

[0016] The present invention has at least the following beneficial effects: First, in the signal generation stage, the scheme processes the reference signal characterizing the target conduction state through an inverting and an inverter, respectively, to generate first and second differential signals with equal amplitude but opposite phase. This step establishes the complementary signal sources required for differential transmission. Second, in the drive execution stage, these two inverted signals are applied to the positive and negative terminals of the optocoupler's LED, respectively. The conduction of the optocoupler depends on the voltage difference between the positive and negative terminals, i.e., the differential voltage, thereby achieving precise control over the target conduction state of the optocoupler. When the circuit encounters external common-mode noise, the noise is coupled to the positive and negative terminals of the LED simultaneously, in phase, and with equal amplitude. Due to the characteristics of differential drive, the optocoupler only responds to the difference between the signals at both ends, and the potential fluctuations generated by the common-mode noise at both ends cancel each other out, keeping the net voltage difference across the diode constant. Therefore, common-mode noise cannot form an effective interference current in the loop, thus achieving noise cancellation and significantly improving the reliability of the drive circuit in complex electromagnetic environments. Attached Figure Description

[0017] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0018] Figure 1 This is a schematic diagram of a signal conditioning unit in an optocoupler isolation system that resists common-mode noise interference. Figure 2 This is a circuit diagram of an inverter and an inverter in an optocoupler isolation system that resists common-mode noise interference. Figure 3 This is a circuit diagram of a signal conversion module in an optocoupler isolation system that resists common-mode noise interference; Figure 4 This is another schematic diagram of the signal conditioning unit in an optocoupler isolation system that resists common-mode noise interference; Figure 5 This is a circuit diagram of a NAND gate logic submodule in an optocoupler isolation system that resists common-mode noise interference. Figure 6 This is a circuit diagram of a steady-state trigger submodule in an optocoupler isolation system that is resistant to common-mode noise interference. Figure 7 This is a circuit diagram showing the connection between the signal conversion module and the optocoupler in an optocoupler isolation system that resists common-mode noise interference. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] It should be noted that although functional modules are divided in the system diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the system or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, and the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0021] In the existing technology field, optocouplers are core devices for achieving electrical isolation and signal transmission in power electronic systems. They isolate control circuits from power circuits through optical signals and are widely used in driving power electronic devices such as IGBTs, MOSFETs, SICMOS, and GANs. During operation, the input signal excites an LED to emit light, and the optical signal is transmitted through an isolation medium to a photodetector, where it is converted into an electrical signal to drive the power electronic device.

[0022] Traditional optocoupler driver circuits use a high-level voltage signal connected to the positive terminal of the optocoupler LED, and a logic device or microcontroller control signal connected to the negative terminal. The on / off state of the optocoupler is controlled by controlling the negative terminal. This is the so-called traditional optocoupler driver circuit connection. While simple, this connection lacks sufficient anti-interference capability. Under conditions of high-power power supplies, large circuit board sizes, and long PCB traces, noise and ripple at the optocoupler LED terminal can easily superimpose onto the signal and couple to the photodetector, affecting the drive level of the power electronic devices. This limits the length of the PCB traces driven by the power electronic devices and makes them susceptible to interference. Increased losses in the power electronic devices significantly increase the probability of mis-conduction. If applied to bridge power conversion circuits, the risk of system failure is greatly increased.

[0023] In particular, in photovoltaic inverter applications, the long cables (tens to hundreds of meters long) between the solar panels and the inverter cause parasitic inductance and capacitance to interact with high-speed switching devices (such as IGBTs) inside the inverter, generating high-amplitude, high-frequency common-mode noise. This common-mode noise can couple into traditional single-ended optocoupler drive circuits through a reference ground loop, easily causing mis-turn-on of the IGBTs, especially near the dead time of the bridge circuit, potentially leading to shoot-through of the upper and lower bridge arms, seriously threatening system reliability. Existing general-purpose anti-interference circuits are insufficient to effectively suppress common-mode noise in such specific scenarios.

[0024] To address the problems in the prior art, this application provides an optocoupler driving circuit that resists common-mode noise, enabling it to drive optocoupler light-emitting diodes while effectively canceling common-mode noise and improving the anti-interference capability of the driving circuit. The following are various embodiments of this technical solution.

[0025] This technical solution provides a common-mode noise interference-resistant optical coupling isolation system, including an optical coupling isolation unit and a signal conditioning unit for implementing a differential driving method to resist common-mode noise interference.

[0026] The optocoupler isolation unit includes a primary-side light-emitting device and a secondary-side photosensitive device. The first output terminal and the second output terminal of the signal conditioning unit are connected to the positive and negative terminals of the primary-side light-emitting device, respectively, to convert the first differential signal and the second differential signal into voltage difference signals applied to the positive and negative terminals of the primary-side light-emitting device, so as to control the conduction state of the primary-side light-emitting device and the switching state of the secondary-side photosensitive device.

[0027] Specifically, a differential driving method for resisting common-mode noise interference includes: (1) The reference drive signal characterizing the target conduction state is input to the in-phase and the inverter respectively, and the first differential signal is generated by the in-phase and the second differential signal is generated by the inverter. The amplitude of the first differential signal and the second differential signal are equal and the phase is opposite.

[0028] (2) A differential voltage is generated based on the first differential signal and the second differential signal and input to the optocoupler through the positive and negative terminals of the light-emitting diode of the optocoupler, so as to control the optocoupler to be in the target conduction state according to the voltage difference between the positive and negative terminals of the light-emitting diode.

[0029] Specifically, this differential driving method for resisting common-mode noise interference also includes: Acquire the original modulation pulse signal; in response to the rising edge of the original modulation pulse signal, start the first delay timer, and output a high level when the first delay timer ends; in response to the falling edge of the original modulation pulse signal, start the second delay timer, and output a low level when the second delay timer ends; perform a logical AND operation between the high level and the low level to eliminate the intermediate uncertainty generated by the original modulation pulse signal during the delay transition, and output the waveform-processed reference drive signal.

[0030] Understandably, in this embodiment, firstly, during the signal generation stage, the scheme processes the reference signal characterizing the target conduction state through an inverting and an inverter, respectively, to generate first and second differential signals with equal amplitude and opposite phase. This step establishes the complementary signal sources required for differential transmission. Secondly, during the drive execution stage, these two inverted signals are respectively applied to the positive and negative terminals of the optocoupler's LED. The conduction of the optocoupler depends on the voltage difference between the positive and negative terminals, i.e., the differential voltage, thereby achieving precise control over the target conduction state of the optocoupler. When the circuit encounters external common-mode noise, the noise is simultaneously, in phase, and with equal amplitude coupled to the positive and negative terminals of the LED. Due to the characteristics of differential drive, the optocoupler only responds to the difference between the signals at both ends, and the potential fluctuations generated by the common-mode noise at both ends cancel each other out, keeping the net voltage difference across the diode constant. Therefore, common-mode noise cannot form an effective interference current in the loop, thus achieving noise cancellation and significantly improving the reliability of the drive circuit in complex electromagnetic environments.

[0031] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the signal conditioning unit in an optocoupler isolation system that resists common-mode noise interference.

[0032] The signal conditioning unit provided in this embodiment includes a signal processing module and a signal conversion module.

[0033] The signal processing module includes an inverting unit and an inverter; the inverting unit is used to convert the reference drive signal into a first differential signal that is in phase with the reference drive signal; the inverter is used to convert the reference drive signal into a second differential signal that is out of phase with the reference drive signal.

[0034] The signal conversion module includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. It is used to input a first differential signal through the first input terminal, input a second differential signal through the second input terminal, and convert the first differential signal and the second differential signal into differential voltages and output them through the first output terminal and the second output terminal of the signal conversion module. The first output terminal and the second output terminal of the signal conversion module correspond to the first output terminal and the second output terminal of the signal conditioning unit.

[0035] Please refer to Figure 2 , Figure 2 This is a circuit diagram of the inverter and inverter in an optocoupler isolation system that resists common-mode noise interference.

[0036] In some embodiments, such as Figure 2 As shown, the inverting circuit uses an inverting buffer chip U1 of model number SN74ACT244U1, and the inverter uses an inverting buffer chip U3 of model number CD74ACT540.

[0037] In some embodiments, the signal conversion module includes a first resistor component, a second resistor component, and a third resistor component; one end of the first resistor component serves as a first input terminal of the signal conversion module, and the other end of the first resistor component serves as a first output terminal of the signal conversion module; one end of the second resistor component serves as a second input terminal of the signal conversion module, and the other end of the second resistor component serves as a second output terminal of the signal conversion module; one end of the third resistor component is connected to the other end of the first resistor component, and the other end of the third resistor component is connected to the other end of the second resistor component.

[0038] Understandably, this signal conditioning unit, by constructing a differential drive architecture, achieves effective driving of the optocoupler light-emitting diode (LED) and suppression of common-mode noise, thereby improving the circuit's anti-interference capability.

[0039] The signal processing module uses inverting and inverting circuits to convert a single reference drive signal into two differential signals (a first differential signal and a second differential signal) with opposite phases and the same amplitude.

[0040] The signal conversion module inputs the two differential signals to the optocoupler through a resistor network.

[0041] Because the two signals are out of phase, their differential voltage is twice the amplitude of a single signal, providing sufficient driving voltage difference for the optocoupler LED. When the circuit is subjected to external electromagnetic interference, common-mode noise with the same phase and amplitude is usually induced at the two input terminals. Due to the symmetrical resistor structure of the signal conversion module (the first and second resistor components are connected accordingly), the two common-mode noises remain synchronized during transmission. When performing differential operation at the optocoupler input terminals, the common-mode noise cancels each other out (V_{noise_diff} = V_{noise} - V_{noise} = 0), thereby preventing noise amplification or false triggering and significantly improving the system's signal-to-noise ratio and anti-interference stability.

[0042] Please refer to Figure 3 , Figure 3 This is a circuit diagram of a signal conversion module in an optocoupler isolation system that resists common-mode noise interference.

[0043] In some embodiments, such as Figure 3As shown, the first resistor unit includes a first resistor R2, the second resistor unit includes a second resistor R5, and the third resistor unit includes a third resistor R3, a fourth resistor R4, and a first capacitor C3. One end of the first resistor R2 serves as the first input terminal of the signal conversion module, and the other end of the first resistor R2 serves as the first output terminal of the signal conversion module. One end of the second resistor R5 serves as the second input terminal of the signal conversion module, and the other end of the second resistor R5 serves as the second output terminal of the signal conversion module. One end of the third resistor R3 is connected to one end of the first resistor R2, and the other end of the third resistor R3 is connected to one end of the second resistor R5. One end of the fourth resistor R4 is connected to the other end of the first resistor R2, and the other end of the fourth resistor R4 is connected to the other end of the second resistor R5. The first capacitor C3 is connected in parallel with the third resistor R3 and the fourth resistor R4.

[0044] Please refer to Figure 4 , Figure 4 This is another structural schematic diagram of a signal conditioning unit in an optocoupler isolation system that resists common-mode noise interference.

[0045] In some embodiments, an optocoupler driving circuit for resisting common-mode noise further includes a delay module; the delay module is used to acquire the original modulation pulse signal; in response to the rising edge of the original modulation pulse signal, start a first delay timing, and output a high level when the first delay timing ends; in response to the falling edge of the original modulation pulse signal, start a second delay timing, and output a low level when the second delay timing ends; perform a logical AND operation between the high level and the low level to eliminate the intermediate uncertainty generated by the original modulation pulse signal during the delay transition, and output a waveform-processed reference driving signal.

[0046] In some embodiments, the delay module includes a steady-state trigger submodule and a NAND gate logic submodule; the input terminal of the steady-state trigger submodule serves as the input terminal of the delay module and is used to adjust the delay time of the modulated pulse signal; the first and second output terminals of the steady-state trigger submodule are connected to the first and second input terminals of the NAND gate logic submodule respectively, and the output terminal of the NAND gate logic submodule serves as the output terminal of the delay module and is used to output the modulated pulse signal after the delay time adjustment and the signal waveform adjustment.

[0047] Understandably, this embodiment utilizes steady-state triggers and logic gates to perform edge delay and logic synthesis processing on the original pulse. This method effectively eliminates intermediate uncertainties (such as glitches or metastability) generated during the transition between the rising and falling edges of the signal, resulting in a reference drive signal with a regular output waveform. Combined with the original differential drive anti-interference mechanism, this scheme not only suppresses external common-mode noise but also purifies the input signal at its source, providing dual protection for the timing accuracy and operational stability of the optocoupler drive circuit, and significantly reducing the risk of false triggering.

[0048] Please refer to Figure 5 , Figure 5 This is a circuit diagram of a NAND gate logic submodule in an optocoupler isolation system that resists common-mode noise interference.

[0049] like Figure 5 As shown, the NAND gate logic submodule uses a dual-channel NAND gate chip U6 with model number NL27WZ00.

[0050] In some embodiments, the steady-state trigger submodule includes a dual-channel monostable trigger, a first adjustable RC component, and a second adjustable RC component.

[0051] The signal input terminal of the dual-channel monostable multivibrator serves as the input terminal of the delay module, and the output terminal of the dual-channel monostable multivibrator serves as the output terminal of the delay module.

[0052] The first adjustable RC component is connected to the first timing signal terminal of the dual-channel monostable multivibrator. The first adjustable RC component includes a first resistor and a first capacitor. One end of the first resistor is connected to the first timing pin of the dual-channel monostable multivibrator, and the other end of the first resistor is connected to the positive terminal of the power supply. One end of the first capacitor is connected to the common terminal of the first resistor and the first timing pin, and the other end of the first capacitor is grounded.

[0053] The second adjustable RC component is connected to the second timing signal terminal of the dual-channel monostable multivibrator. The second adjustable RC component includes a second resistor and a second capacitor. One end of the second resistor is connected to the second timing pin of the dual-channel monostable multivibrator, and the other end of the second resistor is connected to the positive terminal of the power supply. One end of the second capacitor is connected to the common terminal of the second resistor and the second timing pin, and the other end of the second capacitor is grounded.

[0054] Understandably, this embodiment allows for precise setting of the delay time by adjusting the parameters of the resistors and capacitors, thereby adapting to the driving requirements of different frequencies and pulse widths and effectively eliminating signal edge jitter and intermediate uncertainties. This hardware-level delay adjustment mechanism, combined with the original differential common-mode noise suppression architecture, not only purifies the input signal at its source but also enhances the system's adaptability to complex electromagnetic environments, ensuring that the optocoupler drive circuit maintains high timing accuracy and stability under high-frequency, high-noise conditions.

[0055] Please refer to Figure 6 , Figure 6 This is a circuit diagram of a steady-state trigger submodule in an optocoupler isolation system that is resistant to common-mode noise interference.

[0056] In some embodiments, the dual-channel monostable multivibrator is a CD4098 dual-channel monostable multivibrator U5.

[0057] In some embodiments, the first adjustable resistor-capacitor unit includes a first preset resistor R6 and a first preset capacitor C5.

[0058] One end of the first preset resistor R6 is connected to the first timing signal terminal of the dual-channel monostable multivibrator, and the other end of the first preset resistor R6 is used to connect to the power supply; one end of the first preset capacitor C5 is connected to the first timing signal terminal of the dual-channel monostable multivibrator, and the other end of the first preset capacitor C5 is grounded.

[0059] The second adjustable resistor-capacitor unit includes a second preset resistor R7 and a second preset capacitor C6; one end of the second preset resistor R7 is connected to the second timing signal terminal of the dual-channel monostable multivibrator, and the other end of the second preset resistor R7 is used to connect to the power supply; one end of the second preset capacitor C6 is connected to the second timing signal terminal of the dual-channel monostable multivibrator, and the other end of the second preset capacitor C6 is grounded.

[0060] In some embodiments, the steady-state trigger unit further includes a third preset resistor R8, a fourth preset resistor R9, a third preset capacitor C7, and a fourth preset capacitor C8.

[0061] One end of the third preset resistor R8 is connected to the first output terminal of the dual-channel monostable multivibrator via the third preset capacitor C7, and the other end of the third preset resistor R8 is used to connect to the power supply; one end of the fourth preset resistor R9 is connected to the second output terminal of the dual-channel monostable multivibrator via the fourth preset capacitor C8, and the other end of the fourth preset resistor R9 is used to connect to the power supply.

[0062] Understandably, this solution adds an RC coupling network consisting of resistors and capacitors to the output of the delay module. This structure utilizes the DC blocking and AC passing characteristics of capacitors to convert the output signal of the monostable multivibrator into a differential pulse, retaining only the transition information of the signal edge. This process effectively filters out the DC component and low-frequency noise during the steady-state of the signal, preventing logic lock-up or malfunctions that may occur due to the input signal maintaining a certain level for a long time. Combined with the aforementioned common-mode noise suppression and delay debouncing techniques, this solution constructs a comprehensive protection system from signal shaping and timing control to noise filtering, significantly improving the signal purity and operational reliability of the optocoupler drive circuit under strong interference environments.

[0063] In some embodiments, an optocoupler isolation system for resisting common-mode noise interference further includes a secondary-side power supply purification unit, which is connected in series in the power supply circuit of the secondary-side photosensitive device of the optocoupler isolation unit. The secondary-side power supply purification unit is used to suppress the high-frequency differential-mode ripple of power circuit ground bounce noise conducted to the power supply circuit, so that the driving voltage amplitude provided by the secondary-side photosensitive device to the gate of the power electronic switching device during the output high level is within a preset voltage value range.

[0064] Understandably, this embodiment introduces a power supply purification unit on the secondary side of the optocoupler isolation system, constructing a defense mechanism against power supply noise. This unit is connected in series in the secondary power supply circuit and is specifically used to suppress high-frequency differential-mode ripple caused by power circuit ground bounce, preventing it from coupling to the sensitive drive power supply terminal. This design ensures that the amplitude of the drive voltage is strictly maintained within a preset range during the output high level, effectively avoiding the risk of insufficient gate drive or false turn-on due to power supply fluctuations. Combined with the aforementioned differential common-mode rejection and signal delay debouncing technology, end-to-end purification from signal transmission to power supply is achieved, greatly improving the drive stability and system reliability of power electronic switching devices under complex operating conditions.

[0065] Please refer to Figure 7 , Figure 7 This is a circuit diagram showing the connection between the signal conversion module and the optocoupler in an optocoupler isolation system that resists common-mode noise interference.

[0066] like Figure 7 As shown, the optocoupler used is either NSI6801EB or TLP152 driving optocoupler U2.

[0067] The optocoupler power supply filter circuit includes a resistor R1, a diode D1, a capacitor EC1, and a capacitor C2. One end of the resistor R1 is used to connect to a 15V power supply, and the other end of the resistor R1 is connected to the capacitor EC1 through the diode D1. The capacitor C2 is connected in parallel with the capacitor EC1.

[0068] Please see Figure 2 , 3 In the common-mode noise-resistant optocoupler drive circuit of this technical solution, the generated PWM signal is input to pins 4 (+TR1) and 11 (-TR2) of the dual-channel monostable multivibrator U5 via logic devices or a microcontroller. When the rising edge is detected at pin +TR1 (positive trigger) of U5 (pin 4), the first-stage monostable multivibrator of U5 is triggered, and pin 6 (Q1) of U5 outputs a high level. The duration of this high level is determined by R6 and C5, i.e., the delay time T1 ≈ 0.69 * R6 * C5. When the falling edge is detected at pin -TR2 (negative trigger) of U5 (pin 11), the second-stage monostable multivibrator of U5 is triggered, and pin 10 (Q2) of U5 outputs a low level. The duration of this low level is determined by R7 and C6, i.e., the delay time T2 ≈ 0.69 * R7 * C6; the output signals of pins Q1 and Q2 are shaped and buffered by the NAND gate circuit composed of U6 to ensure the stability and reliability of the output signal, and finally the controllable and precise delayed signal PWM_1 is obtained, and the delay time T1 and T2 are adjustable.

[0069] The signal PWM_1 is simultaneously distributed to the non-inverter 3 and the inverter 4. The complementary differential buffer signals PWM_Positive and PWM_Negative output by the non-inverter 3 and the inverter 4 are connected to the matching network 5 at the LED input of the optocoupler. After current limiting, they enter the LED port ELV side of the driver optocoupler 6. The photodetector outputs the PWMOUT signal on the high voltage side to drive the power electronic device. The power supply filter current 7 of the optocoupler provides a stable power supply for driving the power electronic device.

[0070] The connection between inverting circuit 3 and inverter 4 generates complementary differential signals. When inverting circuit 3 outputs a high level, inverter 4 will inevitably output a low level. This, through the matching network 5 at the input of the optocoupler LED, provides a stable turn-on current to the LED side, enabling it to conduct and thus stably output a high level on the high-voltage side. Conversely, when inverting circuit 3 outputs a low level, inverter 4 will inevitably output a high level. This, through the matching network 5 at the input of the optocoupler LED, keeps the LED side off, ensuring a stable low level output on the high-voltage side. Because complementary differential signals are used for driving—the voltage difference between the PWM_Positive and PWM_Negative signals—noise, ripple, and other interference signals are perfectly canceled out, retaining only the effective signal and greatly reducing the probability of false turn-on. This allows for longer drive lines of power electronic devices to transmit over longer distances with less susceptibility to interference, reduces EMI, increases speed, lowers power consumption, and improves application adaptability.

[0071] Understandably, through the dual mechanism of complementary differential drive and precise signal timing management, the complementary differential signal effectively cancels common-mode noise. By controlling the programmable micro-delay of the complementary signal's rising / falling edges, two key effects are achieved: First, a hardware-adjustable and safe 'dead-within-a-dead-time' is created at the signal transition edge, completely eliminating the bridge arm shoot-through risk caused by transmission time dispersion; second, the optimized edge rate reduces high-frequency electromagnetic interference (EMI). The synergistic effect of these two mechanisms makes this circuit particularly suitable for photovoltaic inverter scenarios with severe common-mode noise and long-distance transmission, significantly improving the system's robustness and switching reliability.

[0072] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatuses.

[0073] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0074] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, apparatuses, or units, and may be electrical, mechanical, or other forms.

[0075] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0076] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0077] Although the description of this application has been quite detailed and particularly focused on several of the described embodiments, it is not intended to limit itself to any of these details or embodiments or any particular embodiment. Rather, it should be considered as effectively covering the intended scope of this application by referring to the appended claims and taking into account the prior art, which provides for a broad possible interpretation of these claims. Furthermore, the foregoing description of this application with respect to embodiments foreseeable by the inventors is intended to provide a useful description, and non-substantial modifications to this application that have not yet been foreseen may still represent equivalent modifications.

Claims

1. A differential driving method for resisting common-mode noise interference, characterized in that, The method includes: A reference drive signal characterizing the target conduction state is input to an inverter and an inverter, respectively. A first differential signal is generated by the inverter, and a second differential signal is generated by the inverter. The first differential signal and the second differential signal have the same amplitude and opposite phase. A differential voltage is generated based on the first differential signal and the second differential signal and input to the optocoupler through the positive and negative terminals of the light-emitting diode of the optocoupler, so as to control the optocoupler to be in the target conduction state according to the voltage difference between the positive and negative terminals of the light-emitting diode.

2. The method according to claim 1, characterized in that, The method further includes: Obtain the original modulated pulse signal; In response to the rising edge of the original modulated pulse signal, a first delay timer is started, and a high level is output when the first delay timer ends; In response to the falling edge of the original modulation pulse signal, a second delay timer is started, and a low level is output when the second delay timer ends; The high level and the low level are logically ANDed to eliminate the intermediate uncertainty generated during the delay transition of the original modulation pulse signal, and the waveform-processed reference drive signal is output.

3. An optically isolated system for resisting common-mode noise interference, characterized in that, The system includes an optocoupler isolation unit and a signal conditioning unit for implementing the differential driving method for resisting common-mode noise interference as described in claim 1; The optical coupling isolation unit includes a primary-side light-emitting device and a secondary-side photosensitive device; The first and second output terminals of the signal conditioning unit are connected to the positive and negative terminals of the primary-side light-emitting device, respectively, to convert the first differential signal and the second differential signal into voltage difference signals applied to the positive and negative terminals of the primary-side light-emitting device, so as to control the conduction state of the primary-side light-emitting device and the switching state of the secondary-side photosensitive device.

4. The system according to claim 3, characterized in that, The signal conditioning unit includes a signal processing module and a signal conversion module; The signal processing module includes an inverting unit and an inverter; The inverting unit is used to convert the reference driving signal into a first differential signal that is in phase with the reference driving signal; The inverter is used to convert the reference drive signal into a second differential signal that is inverted by the reference drive signal; The signal conversion module includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. It is used to input the first differential signal through the first input terminal, input the second differential signal through the second input terminal, and convert the first differential signal and the second differential signal into differential voltages and output them through the first output terminal and the second output terminal of the signal conversion module. The first output terminal and the second output terminal of the signal conversion module correspond to the first output terminal and the second output terminal of the signal conditioning unit.

5. The system according to claim 4, characterized in that, The signal conversion module includes a first resistor assembly, a second resistor assembly, and a third resistor assembly; One end of the first resistor component serves as the first input terminal of the signal conversion module, and the other end of the first resistor component serves as the first output terminal of the signal conversion module. One end of the second resistor component serves as the second input terminal of the signal conversion module, and the other end of the second resistor component serves as the second output terminal of the signal conversion module; One end of the third resistor assembly is connected to the other end of the first resistor assembly, and the other end of the third resistor assembly is connected to the other end of the second resistor assembly.

6. The system according to claim 5, characterized in that, The first resistor assembly includes a first resistor, the second resistor assembly includes a second resistor, and the third resistor assembly includes a third resistor, a fourth resistor, and a first capacitor; One end of the first resistor serves as the first input terminal of the signal conversion module, and the other end of the first resistor serves as the first output terminal of the signal conversion module. One end of the second resistor serves as the second input terminal of the signal conversion module, and the other end of the fourth resistor serves as the second output terminal of the signal conversion module. One end of the third resistor is connected to one end of the first resistor, and the other end of the third resistor is connected to one end of the second resistor; One end of the fourth resistor is connected to the other end of the first resistor, and the other end of the fourth resistor is connected to the other end of the second resistor; The first capacitor is connected in parallel with the second resistor and the third resistor.

7. The system according to claim 4, characterized in that, The signal conditioning unit further includes a delay module for: Obtain the original modulated pulse signal; In response to the rising edge of the original modulated pulse signal, a first delay timer is started, and a high level is output when the first delay timer ends; In response to the falling edge of the original modulation pulse signal, a second delay timer is started, and a low level is output when the second delay timer ends; The high level and the low level are logically ANDed to eliminate the intermediate uncertainty generated during the delay transition of the original modulation pulse signal, and the waveform-processed reference drive signal is output.

8. The system according to claim 7, characterized in that, The delay module includes a steady-state trigger submodule, which includes a dual-channel monostable trigger, a first adjustable RC component, and a second adjustable RC component. The signal input terminal of the dual-channel monostable multivibrator serves as the input terminal of the delay module, and the output terminal of the dual-channel monostable multivibrator serves as the output terminal of the delay module. The first adjustable resistor-capacitor assembly is connected to the first timing signal terminal of the dual-channel monostable multivibrator; the first adjustable resistor-capacitor assembly includes a first resistor and a first capacitor, one end of the first resistor is connected to the first timing pin of the dual-channel monostable multivibrator, the other end of the first resistor is connected to the positive terminal of the power supply, one end of the first capacitor is connected to the common terminal of the first resistor and the first timing pin, and the other end of the first capacitor is grounded. The second adjustable resistor-capacitor assembly is connected to the second timing signal terminal of the dual-channel monostable multivibrator; the second adjustable resistor-capacitor assembly includes a second resistor and a second capacitor, one end of the second resistor is connected to the second timing pin of the dual-channel monostable multivibrator, the other end of the second resistor is connected to the positive terminal of the power supply, one end of the second capacitor is connected to the common terminal of the second resistor and the second timing pin, and the other end of the second capacitor is grounded.

9. The system according to claim 8, characterized in that, The steady-state trigger submodule also includes a third resistor, a fourth resistor, a third capacitor, and a fourth capacitor; One end of the third resistor is connected to the second output pin of the dual-channel monostable multivibrator via the third capacitor, and the other end of the third resistor is used to connect to the power supply. One end of the fourth resistor is connected to the first output pin of the dual-channel monostable multivibrator via the fourth capacitor, and the other end of the fourth resistor is used to connect to the power supply.

10. The system according to claim 3, characterized in that, The system also includes a secondary power supply purification unit, which is connected in series in the power supply circuit of the secondary photosensitive device of the optocoupler isolation unit. It is used to suppress the high-frequency differential mode ripple of power circuit ground bounce noise conducted to the power supply circuit, so that the driving voltage amplitude provided by the secondary photosensitive device to the gate of the power electronic switching device during the output high level is within a preset voltage range.

Images