A hybrid cascaded common-mode electromagnetic interference filter for servo drive systems and a design method thereof

Abstract

The application discloses a hybrid cascade common-mode electromagnetic interference filter suitable for a servo driving system and a design method thereof, and belongs to the filter field, and comprises a first filter module, a second filter module and a third filter module, a third end of a linear stable impedance network is connected to a first end of the first filter module, a fourth end of the linear stable impedance network is connected to a second end of the first filter module, a third end of the second filter module is connected to a third end of the first filter module, a second end of the second filter module is connected to a fourth end of the first filter module, a third end of the second filter module is connected to a first end of the third filter module, a fourth end of the second filter module is connected to a second end of the third filter module, a fifth end of the second filter module is grounded, a third end of the third filter module is connected to a first end of a permanent magnet servo driving system, and a fourth end of the third filter module is connected to a second end of the permanent magnet servo driving system. The application significantly improves the insertion loss performance in a wide frequency range.

Description

Technical Field

[0001] This invention relates to the field of filter technology, and in particular to a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems and its design method. Background Technology

[0002] Servo systems are crucial in numerous applications, including industry and aerospace. Currently, electric servo drive systems primarily employ Pulse Width Modulation (PWM) to control the inverter's switching states, thereby obtaining the required voltage waveform to power the servo motor. The PWM operating principle dictates that the inverter output signal, in addition to the fundamental frequency, contains a significant amount of high-order harmonic components. This means that a large amount of harmonic energy is concentrated at the switching frequency and its integer multiples, generating substantial electromagnetic interference (EMI). Furthermore, the high-speed turn-on and turn-off behavior of the power switching transistors during PWM implementation generates high-frequency voltage and current pulse signals, which is also a significant source of EMI in electric servo drive systems. To meet the demands of high power density, integration, and miniaturization, servo drive systems need to integrate a large number of electronic and mechanical devices within a relatively small space, leading to an increasingly complex and harsh electromagnetic environment.

[0003] Currently, research on electromagnetic interference (EMI) suppression methods for servo drive systems mainly falls into two categories: active suppression strategies targeting noise sources and passive suppression strategies targeting noise propagation paths. Common active suppression strategies include improving modulation strategies and modifying the switching behavior of switching devices in the circuit. Improving modulation strategies primarily involves optimizing the system's switching strategy, such as random switching frequency modulation or chaotic modulation, to disperse the energy of the switching frequency and its harmonics, thus reducing the peak EMI level. This approach requires no additional hardware but can impact system performance. Improving the switching behavior of switching devices mainly involves modifying the system's drive circuitry, such as introducing buffer circuits or optimizing gate drives, but this places higher demands on the system's hardware. Passive suppression strategies primarily use EMI filters to cut off the propagation path of EMI. These are mainly divided into active and passive EMI filters. Active EMI filters are smaller in size, but because their amplification circuits currently primarily use operational amplifiers (op-amps), and op-amps have limited high-frequency gain, their effectiveness against high-frequency EMI is relatively poor. Passive electromagnetic interference (EMI) filters are mainly composed of inductors and capacitors, resulting in a relatively large size. However, by rationally designing the system's cutoff frequency, a large insertion loss can be achieved after the cutoff frequency, leading to good suppression of high-frequency EMI. Nevertheless, existing EMI suppression methods still have certain limitations in achieving EMI suppression over a wide frequency range. Summary of the Invention

[0004] The purpose of this application is to overcome the shortcomings of the prior art and provide a hybrid cascaded common-mode electromagnetic interference filter and its design method suitable for servo drive systems, so as to achieve both wide-band electromagnetic interference suppression and equipment miniaturization.

[0005] In a first aspect, this application provides a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems, applied to a permanent magnet servo drive system. The first end of the linear stable impedance network is connected to the first end of the input power supply, the second end of the linear stable impedance network is connected to the second end of the input power supply, and the third and fourth ends of the linear stable impedance network are connected to the permanent magnet servo drive system through the hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems.

[0006] The hybrid cascaded common-mode electromagnetic interference filter for servo drive systems includes: a first filter module, a second filter module, and a third filter module. The first terminal of the first filter module is connected to the third terminal of the linear stable impedance network. The second terminal of the first filter module is connected to the fourth terminal of the linear stable impedance network. The third terminal of the first filter module is connected to the first terminal of the second filter module. The fourth terminal of the first filter module is connected to the second terminal of the second filter module. The third terminal of the second filter module is connected to the first terminal of the third filter module. The fourth terminal of the second filter module is connected to the second terminal of the third filter module. The fifth terminal of the second filter module is grounded. The third terminal of the third filter module is connected to the first terminal of the permanent magnet servo drive system, and the fourth terminal of the third filter module is connected to the second terminal of the permanent magnet servo drive system.

[0007] Optionally, the first filtering module is an active common-mode electromagnetic interference filter, the second filtering module is an active common-mode electromagnetic interference filter, and the third filtering module is a passive filter.

[0008] Optionally, the first filtering module includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a first operational amplifier. The first terminal of the first capacitor is connected to the third terminal of a linear stable impedance network. The second terminal of the first capacitor is connected to the first terminal of the first resistor. The second terminal of the first resistor is connected to the first terminal of the first operational amplifier. The first terminal of the second capacitor is connected to the fourth terminal of the linear stable impedance network. The second terminal of the second capacitor is connected to the first terminal of the first resistor. The first terminal of the second resistor is grounded. The second terminal of the second resistor is connected to the second terminal of the first operational amplifier. The first terminal of the fourth resistor is connected to the first terminal of the first operational amplifier. The second terminal of the fourth resistor is connected to the third terminal of the first operational amplifier. The first terminal of the third resistor is connected to the first terminal of the first capacitor. The second terminal of the third capacitor is connected to the second terminal of the third resistor. The first terminal of the fourth capacitor is connected to the second terminal of the second capacitor. The second terminal of the fourth capacitor is connected to the second terminal of the third resistor.

[0009] Optionally, the second filtering module includes a current transformer, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a second operational amplifier, and a fifth capacitor. The first end of the first winding of the current transformer is connected to the first end of the third capacitor, and the second end of the first winding of the current transformer is connected to the first end of the third filtering module. The first end of the second winding of the current transformer is connected to the first end of the fourth capacitor, and the second end of the second winding of the current transformer is connected to the second end of the third filtering module. The first end of the third winding of the current transformer is connected to the first end of the fifth resistor, and the second end of the third winding of the current transformer is connected to the second end of the fifth resistor. The first end of the sixth resistor is connected to the second end of the fifth resistor, and the second end of the sixth resistor is connected to the first end of the second operational amplifier. The first end of the seventh resistor is connected to the first end of the fifth resistor, and the second end of the seventh resistor is connected to the second end of the second operational amplifier. The first end of the ninth resistor is connected to the first end of the second operational amplifier, and the second end of the ninth resistor is connected to the third end of the second operational amplifier. The first end of the eighth resistor is connected to the third end of the second operational amplifier, and the second end of the eighth resistor is connected to the first end of the fifth capacitor. The second end of the fifth capacitor is grounded.

[0010] Optionally, the third filtering module includes a first inductor and a second inductor. The first end of the first inductor is connected to the second end of the first winding of the current transformer, and the second end of the first inductor is connected to the first end of the permanent magnet servo drive system. The first end of the second inductor is connected to the second end of the second winding of the current transformer, and the second end of the second inductor is connected to the second end of the permanent magnet servo drive system.

[0011] Secondly, this application also provides a design method for a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems, applied to the hybrid cascaded common-mode electromagnetic interference filter for servo drive systems as described in the first aspect, comprising the following steps:

[0012] A first filter module is connected to the output of the linear stable impedance network, and a second filter module is connected to the current compensation terminal of the first filter module to obtain a cascaded active common-mode electromagnetic interference filter.

[0013] The transfer function of the cascaded active common-mode electromagnetic interference filter is determined based on the equivalent circuit, and the insertion loss of the cascaded active common-mode electromagnetic interference filter is determined based on the transfer function of the cascaded active common-mode electromagnetic interference filter.

[0014] A third filter module is connected between the input of the permanent magnet servo drive system and the subsequent stage of the second filter module to obtain a hybrid cascaded common-mode electromagnetic interference filter.

[0015] The transfer function of the hybrid cascaded common-mode electromagnetic interference (EMI) filter is determined based on the equivalent circuit. The insertion loss of the hybrid cascaded common-mode EMI filter is determined based on the transfer function of the hybrid cascaded common-mode EMI filter. The insertion loss of the hybrid cascaded common-mode EMI filter is used to prove the effectiveness of the hybrid cascaded common-mode EMI filter in suppressing electromagnetic interference over a wide frequency range.

[0016] Optionally, the transfer function of the cascaded active common-mode electromagnetic interference filter The expression is:

[0017]

[0018] in, The input current is the linear stable impedance network terminal after being connected to the cascaded active common-mode electromagnetic interference filter. For common-mode current source current, For the noise source impedance, For linear stable impedance network terminal impedance, This is the amplification factor of the first filtering module. This is the amplification factor of the second filtering module. Let be the output impedance, and s be the Laplace operator.

[0019] Optionally, the insertion loss of the cascaded active common-mode electromagnetic interference filter The expression is:

[0020]

[0021] in, The input current is the linear stable impedance network terminal that is not connected to a cascaded active common-mode electromagnetic interference filter. The input current is the linear stable impedance network terminal after being connected to the cascaded active common-mode electromagnetic interference filter. For the noise source impedance, For linear stable impedance network terminal impedance, This is the amplification factor of the first filtering module. This is the amplification factor of the second filtering module. Let be the output impedance, and s be the Laplace operator.

[0022] Optionally, the transfer function of the hybrid cascaded common-mode electromagnetic interference filter The expression is:

[0023]

[0024] in, For the noise source impedance, For linear stable impedance network terminal impedance, This is the amplification factor of the first filtering module. This is the amplification factor of the second filtering module. For output impedance, Let be the impedance of the third filter module, and s be the Laplace operator.

[0025] Optionally, the insertion loss of the hybrid cascaded common-mode electromagnetic interference filter... The expression is:

[0026]

[0027] in, For the noise source impedance, For linear stable impedance network terminal impedance, This is the amplification factor of the first filtering module. This is the amplification factor of the second filtering module. For output impedance, Let be the impedance of the third filter module, and s be the Laplace operator.

[0028] This application provides a hybrid cascaded common-mode electromagnetic interference (EMI) filter and its design method suitable for servo drive systems. Common-mode interference suppression is achieved through a cascaded active EMI filter and a passive filter. By rationally designing the connection position of the common-mode inductor, the low-to-mid-frequency suppression effect of the active filter can be effectively enhanced. A better high-frequency suppression effect is achieved by connecting a smaller passive filter after the cascaded active EMI filter. This fully leverages the low-frequency compensation capability of active devices and the high-frequency suppression reliability of passive devices, while avoiding their limitations in specific frequency bands. It significantly improves insertion loss performance over a wide frequency range and effectively reduces the overall size and weight of the filter compared to traditional passive EMI filters.

[0029] To make the above-mentioned features and advantages of the invention more apparent and understandable, specific embodiments are described below, and detailed descriptions are provided in conjunction with the accompanying drawings. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems provided in one embodiment of this application.

[0032] Figure 2 This is an equivalent circuit diagram of a hybrid cascaded common-mode electromagnetic interference filter for a servo drive system provided in one embodiment of this application.

[0033] Figure 3 This is a flowchart illustrating a design method for a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems, provided in one embodiment of this application.

[0034] Figure 4 This is a block diagram of the common-mode current feedback suppression of a cascaded active common-mode electromagnetic interference filter in a design method for a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems provided in one embodiment of this application.

[0035] Figure 5 This is a block diagram of the common-mode current feedback suppression of a hybrid cascaded common-mode electromagnetic interference filter in a design method for a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems provided in one embodiment of this application.

[0036] Figure 6 This is a comparison of the simulation insertion loss of different electromagnetic interference filters in the design method of a hybrid cascaded common-mode electromagnetic interference filter for servo drive systems provided in one embodiment of this application.

[0037] In the diagram: 1 is a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems; 2 is a linear stable impedance network; 3 is an input power supply; 4 is a permanent magnet servo drive system; 11 is the first filter module; 12 is the second filter module; 13 is the third filter module; 41 is a three-phase inverter bridge; and 42 is a servo motor. Detailed Implementation

[0038] To make the objectives and technical solutions of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0039] In one embodiment, see Figure 1 This application provides a hybrid cascaded common-mode electromagnetic interference filter 1 suitable for servo drive systems. It is applied to a permanent magnet servo drive system 4. The first end of the linear stable impedance network 2 is connected to the first end of the input power supply 3, and the second end of the linear stable impedance network 2 is connected to the second end of the input power supply 3. The third and fourth ends of the linear stable impedance network 2 are connected to the permanent magnet servo drive system 4 through the hybrid cascaded common-mode electromagnetic interference filter 1 suitable for servo drive systems.

[0040] More specifically, the permanent magnet servo drive system 4 includes a three-phase inverter bridge 41 and a servo motor 42. The hybrid cascaded common-mode electromagnetic interference filter 1, the three-phase inverter bridge 41 and the servo motor 42 are connected in sequence for the servo drive system.

[0041] This application provides a hybrid cascaded common-mode electromagnetic interference filter 1 suitable for servo drive systems, comprising a first filter module 11, a second filter module 12, and a third filter module 13. The first end of the first filter module 11 is connected to the third end of a linear stable impedance network 2, the second end of the first filter module 11 is connected to the fourth end of the linear stable impedance network 2, the third end of the first filter module 11 is connected to the first end of the second filter module 12, the fourth end of the first filter module 11 is connected to the second end of the second filter module 12, the third end of the second filter module 12 is connected to the first end of the third filter module 13, the fourth end of the second filter module 12 is connected to the second end of the third filter module 13, the fifth end of the second filter module 12 is grounded, the third end of the third filter module 13 is connected to the first end of a permanent magnet servo drive system 4, and the fourth end of the third filter module 13 is connected to the second end of the permanent magnet servo drive system 4.

[0042] As an example, the voltage across the input power supply 3 is V in .

[0043] As an example, the three-phase inverter bridge 41 may include six power switching devices with anti-parallel diodes. The three-phase inverter bridge 41 inverts DC power into three-phase AC power to provide frequency and voltage adjustable three-phase AC power to drive the servo motor 42.

[0044] As an example, the power switching devices of the three-phase inverter bridge 41 can be IGBTs, MOSFETs, etc. Since the active filter in this embodiment is mainly implemented through an operational amplifier, and operational amplifiers are more suitable for low-voltage scenarios, the power switching devices of the three-phase inverter bridge 41 in this embodiment are MOSFETs.

[0045] For example, please refer to Figure 1 The first filtering module 11 includes capacitors C1, C2, C3, and C4, and resistor R. 11 Resistance R 12 Resistor R2, Resistor R f1 Operational amplifier G1, the first terminal of capacitor C1 is connected to the third terminal of linear stable impedance network 2, and the second terminal of capacitor C1 is connected to resistor R. 11 The first terminal, resistor R 11 The second terminal of capacitor C2 is connected to the first terminal of operational amplifier G1, the first terminal of capacitor C2 is connected to the fourth terminal of linear stabilizing impedance network 2, and the second terminal of capacitor C2 is connected to resistor R. 11The first terminal, resistor R 12 The first terminal is grounded, and the resistor R 12 The second terminal is connected to the second terminal of operational amplifier G1; resistor R f1 The first terminal is connected to the first terminal of operational amplifier G1, and resistor R f1 The second terminal of capacitor C3 is connected to the third terminal of operational amplifier G1; the first terminal of resistor R2 is connected to the third terminal of operational amplifier G1; the first terminal of capacitor C3 is connected to the first terminal of capacitor C1; the second terminal of capacitor C3 is connected to the second terminal of resistor R2; the first terminal of capacitor C4 is connected to the second terminal of capacitor C2; and the second terminal of capacitor C4 is connected to the second terminal of resistor R2.

[0046] As an example, resistor R 11 With resistance R 12 The resistance value is R1.

[0047] As an example, the first end of capacitor C1 and the first end of capacitor C2 are the sampling terminals of the first filter module 11, and the first end of capacitor C3 and the first end of capacitor C4 are the current compensation terminals of the first filter module 11.

[0048] As an example, the first filtering module 11 can be an active common-mode filter. The first filtering module 11 samples the common-mode voltage of the linear stable impedance network 2 through capacitors C1 and C2, amplifies the sampled common-mode voltage in reverse through operational amplifier G1, and converts the amplified common-mode voltage into a compensation current through resistor R2, capacitor C3, and capacitor C4. I com1 .

[0049] For example, please refer to Figure 1 The second filtering module 12 includes a current transformer CT, a resistor R3, and a resistor R. 41 Resistance R 42 Resistor R5, Resistor R f2 Operational amplifier G2, capacitor C5, the first terminal of the first winding N1 of current transformer CT is connected to the first terminal of capacitor C3, and the second terminal of the first winding N1 of current transformer CT is connected to the first terminal of the third filter module 13; the first terminal of the second winding N2 of current transformer CT is connected to the first terminal of capacitor C4, and the second terminal of the second winding N2 of current transformer CT is connected to the second terminal of the third filter module 13; the first terminal of the third winding N3 of current transformer CT is connected to the first terminal of resistor R3, and the second terminal of the third winding N3 of current transformer CT is connected to the second terminal of resistor R3; resistor R... 41 The first terminal is connected to the second terminal of resistor R3, and resistor R 41 The second terminal is connected to the first terminal of operational amplifier G2; resistor R 42 The first terminal is connected to the first terminal of resistor R3, and resistor R 42The second terminal is connected to the second terminal of operational amplifier G2; resistor R f2 The first terminal is connected to the first terminal of operational amplifier G2, and resistor R f2 The second terminal of resistor R5 is connected to the third terminal of operational amplifier G2; the first terminal of resistor R5 is connected to the third terminal of operational amplifier G2, and the second terminal of resistor R5 is connected to the first terminal of capacitor C5, with the second terminal of capacitor C5 grounded. The output compensation current from resistor R5 and capacitor C5 is injected into ground, reducing common-mode current and suppressing common-mode interference.

[0050] As an example, resistor R 41 Resistance R 42 The resistance value is R4.

[0051] As an example, resistor R5 and capacitor C5 are the current compensation terminals of the second filter module 12.

[0052] As an example, the second filtering module 12 can be an active common-mode filter. The second filtering module 12 samples the common-mode current of the linear stable impedance network 2 and the compensation current output by the first filtering module 11 through the current transformer CT. I com1 The sum of these two values ​​yields the new sampled current. I 1 The common-mode interference current is acquired through the third winding N3 of the current transformer CT, and the newly sampled compensation current is transferred through resistor R3. I 1 The signal is converted into a voltage signal, which is then amplified in reverse by operational amplifier G2 and converted into a compensation current through resistor R5 and capacitor C5. I com2 Compared to a single-stage active common-mode electromagnetic interference filter, the new sampling current of the second filter module 12... I 1 The common-mode current of the linear stable impedance network 2 and the compensation current output by the first filter module 11 are... I com1 The sum of these factors generates the compensation current. I com 2 Larger, thus achieving higher insertion loss.

[0053] As an example, the first filter module 11 can be a voltage-sampling, current-compensated active common-mode electromagnetic interference filter (VSCC ACMEF); the second filter module 12 can be a current-sampling, current-compensated active common-mode electromagnetic interference filter (CSCC ACMEF). By connecting the first filter module 11 to the output of the linear stable impedance network 2 and connecting the second filter module 12 after the first filter module 11, a cascaded active common-mode electromagnetic interference filter is formed to achieve better electromagnetic interference suppression.

[0054] For example, please refer to Figure 1 The third filtering module 13 can be a passive filter, and the third filtering module 13 can include an inductor L. CM1 Inductor L CM2 Inductor L CM1 The first terminal is connected to the second terminal of the first winding N1 of the current transformer CT, and the inductance L CM1 The second end is connected to the first end of the permanent magnet servo drive system 4; inductor L CM2 The first terminal is connected to the second terminal of the second winding N2 of the current transformer CT, and the inductance L CM2 The second end is connected to the second end of the permanent magnet servo drive system 4.

[0055] As an example, inductor L CM1 Inductor L CM2 It can be used as a common-mode inductor to suppress high-frequency common-mode electromagnetic interference signals.

[0056] As an example, by connecting a small passive filter between the input terminal of the permanent magnet servo drive system 4 and the current compensation terminal of the second filter module 12, a hybrid cascaded common-mode electromagnetic interference filter is obtained. This can increase the amplification factor of the filter insertion loss function, realize the suppression of high-frequency common-mode electromagnetic interference signals, effectively suppress the high-frequency electromagnetic interference of the permanent magnet servo drive system 4, and enhance the electromagnetic interference suppression performance of the cascaded first filter module 11 and second filter module 12 in the mid-to-low frequency band.

[0057] Please see Figure 2 , Figure 2 This is the equivalent circuit diagram of a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems, where the common-mode current source I... S The generated interference current passes through Z S The noise propagates towards terminal 2 of the linear stable impedance network. The current at the noise source terminal is I2, and the impedance of the linear stable impedance network 2 is Z. L The current flowing into the linear stable impedance network 2 is I. L The first filter module 11 processes the common-mode voltage of the linear stable impedance network 2 based on the amplification factor G1, generating a compensation current I. com1 The common-mode voltage source of the first filter module 11 is V com1 The output impedance of the first filter module 11 is Z. out1 The amplification factor of the second filter module 12 is G2, and the sampling current of the second filter module 12 is I1, where, The compensation current generated by the second filter module 12 is I. com2 The common-mode voltage source of the second filter module 12 is V. com2 The output impedance of the second filter module 12 is Z. out2The equivalent impedance of the third filter module 13 is Z. LCM The current of the third filter module 13 is I. LCM .

[0058] As an example, the hybrid cascaded common-mode electromagnetic interference filter applicable to servo drive systems in this application is mainly aimed at common-mode electromagnetic interference to the ground loop.

[0059] In the aforementioned hybrid cascaded common-mode electromagnetic interference filter applicable to servo drive systems, the low-to-mid-frequency suppression effect of the active filter can be enhanced by connecting a smaller third filter module 13, effectively suppressing high-frequency electromagnetic interference in the system. By cascading the first filter module 11 and the second filter module 12, and setting the second filter module 12 to sample the sum of the common-mode current of the linear stable impedance network 2 and the compensation current output by the first filter module 11, a larger compensation current can be obtained, thereby achieving higher insertion loss and suppressing wide-band electromagnetic interference.

[0060] In one embodiment, see Figure 3 This application provides a design method for a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems. The design method for a hybrid cascaded common-mode electromagnetic interference filter suitable for servo drive systems may include the following steps: steps S1 to S4.

[0061] Step S1: Connect the first filter module to the output of the linear stable impedance network, and connect the second filter module to the current compensation terminal of the first filter module to obtain a cascaded active common-mode electromagnetic interference filter.

[0062] Step S2: Determine the transfer function of the cascaded active common-mode electromagnetic interference filter based on the equivalent circuit, and determine the insertion loss of the cascaded active common-mode electromagnetic interference filter based on the transfer function of the cascaded active common-mode electromagnetic interference filter.

[0063] Step S3: Connect a third filter module between the input of the permanent magnet servo drive system and the subsequent stage of the second filter module to obtain a hybrid cascaded common-mode electromagnetic interference filter.

[0064] Step S4: Determine the transfer function of the hybrid cascaded common-mode electromagnetic interference filter based on the equivalent circuit, determine the insertion loss of the hybrid cascaded common-mode electromagnetic interference filter based on the transfer function, and prove the effectiveness of the hybrid cascaded common-mode electromagnetic interference filter in suppressing electromagnetic interference over a wide frequency range by using the insertion loss of the hybrid cascaded common-mode electromagnetic interference filter.

[0065] This application presents a design method for a hybrid cascaded common-mode electromagnetic interference (EMI) filter applicable to servo drive systems. First, a first and second filter module are cascaded to form a cascaded active structure. The transfer function is derived using equivalent circuits, and the insertion loss is determined, providing a foundation for verifying the filter performance. Then, a third filter module is introduced to construct a hybrid cascaded structure. The effect is again verified through transfer function and insertion loss analysis, effectively integrating the advantages of active and passive filtering. The cascaded design enhances the filtering depth, the active characteristics improve adaptability to impedance variations, and the addition of the third filter module further expands the effective suppression frequency band. Furthermore, it is smaller in size compared to traditional passive EMI filters. By deriving the transfer function and insertion loss step-by-step, the filtering performance of different structures is accurately quantified, ultimately proving the effectiveness of the hybrid cascaded filter in suppressing EMI over a wide frequency band. This improves its adaptability to complex electromagnetic environments and meets the filtering requirements of diverse scenarios.

[0066] In step S1, please refer to Figure 3 In step S1, a first filter module is connected to the output of the linear stable impedance network, and a second filter module is connected to the current compensation terminal of the first filter module to obtain a cascaded active common-mode electromagnetic interference filter.

[0067] As an example, the output impedance Z of the first filter module can be set. out1 With the output impedance Z of the second filter module 12 out2 The impedance values ​​are the same, both are Z. out ,Right now .

[0068] Specifically, the third end of the linear stable impedance network 2 is connected to the first end of the first filter module 11, the fourth end of the linear stable impedance network 2 is connected to the second end of the first filter module 11, the third end of the first filter module 11 is connected to the first end of the second filter module 12, and the fourth end of the first filter module 11 is connected to the second end of the second filter module 12, thus obtaining a cascaded active common-mode electromagnetic interference filter.

[0069] In step S2, please refer to Figure 3 In step S2, the transfer function of the cascaded active common-mode electromagnetic interference filter is determined based on the equivalent circuit, and the insertion loss of the cascaded active common-mode electromagnetic interference filter is determined based on the transfer function of the cascaded active common-mode electromagnetic interference filter.

[0070] Specifically, the equivalent circuit of a cascaded active common-mode electromagnetic interference (EMI) filter is constructed. Based on this equivalent circuit, the common-mode current feedback suppression process of the cascaded active EEM filter is analyzed. Finally, the transfer function of the cascaded active EEM filter is determined based on this common-mode current feedback suppression process. .

[0071] As an example, Figure 4 This is a block diagram of the common-mode current feedback suppression of a cascaded active common-mode electromagnetic interference filter. Figure 4 It can be seen that the current I flowing into the linear stable impedance network 2 L The first filter module 11 respectively And linear stable impedance network 2 impedance The values ​​are then added together, and the sum is then passed through the admittance of the first filtering module 11. The compensation current of the first filter module 11 is obtained. The current I flowing into the linear stable impedance network 2 L Compensation current with the first filter module 11 After addition, the mixture passes through the second filter module 12. The current I flowing into the linear stable impedance network 2 L Impedance via linear stable impedance network 2 The two values ​​are added together and then passed through the admittance of the second filter module 12. The compensation current of the second filter module 12 is obtained. ; to compensate the current of the first filter module 11 Compensation current with the second filter module 12 The sum is injected into the circuit to achieve compensation.

[0072] As an example, the transfer function of a cascaded active common-mode electromagnetic interference filter. The expression is:

[0073]

[0074] in, The input current is the linear stable impedance network terminal after being connected to the cascaded active common-mode electromagnetic interference filter. For common-mode current source current, For the noise source impedance, For linear stable impedance network terminal impedance, This is the amplification factor of the first filtering module. This is the amplification factor of the second filtering module. Let be the output impedance, and s be the Laplace operator.

[0075] Furthermore, based on the transfer function of the cascaded active common-mode electromagnetic interference filter... The insertion loss of a cascaded active common-mode electromagnetic interference filter can be derived. .

[0076] As an example, the insertion loss of a cascaded active common-mode electromagnetic interference filter. The expression is:

[0077]

[0078] in, The input current is the linear stable impedance network terminal that is not connected to a cascaded active common-mode electromagnetic interference filter. The input current is the linear stable impedance network terminal after being connected to the cascaded active common-mode electromagnetic interference filter. For the noise source impedance, For linear stable impedance network terminal impedance, This is the amplification factor of the first filtering module. This is the amplification factor of the second filtering module. Let be the output impedance, and s be the Laplace operator.

[0079] In step S3, please refer to Figure 3 In step S3, a third filter module is connected between the input end of the permanent magnet servo drive system and the subsequent stage of the second filter module to obtain a hybrid cascaded common-mode electromagnetic interference filter.

[0080] Specifically, the second end of the first winding N1 of the current transformer CT is connected to the first end of the third filter module 13, the second end of the second winding N2 of the current transformer CT is connected to the second end of the third filter module 13, the first end of the permanent magnet servo drive system 4 is connected to the third end of the third filter module 13, and the second end of the permanent magnet servo drive system 4 is connected to the fourth end of the third filter module 13, thus obtaining a hybrid cascaded common-mode electromagnetic interference filter.

[0081] As an example, the third filtering module 13 can use a smaller passive filter, which can not only effectively suppress high-frequency electromagnetic interference, but also enhance the electromagnetic interference suppression performance of the cascaded active common-mode electromagnetic interference filter in the mid-to-low frequency band.

[0082] In step S4, please refer to Figure 3 In step S4, the transfer function of the hybrid cascaded common-mode electromagnetic interference filter is determined based on the equivalent circuit. The insertion loss of the hybrid cascaded common-mode electromagnetic interference filter is determined based on the transfer function of the hybrid cascaded common-mode electromagnetic interference filter. The insertion loss of the hybrid cascaded common-mode electromagnetic interference filter is used to prove the effectiveness of the hybrid cascaded common-mode electromagnetic interference filter in suppressing electromagnetic interference over a wide frequency range.

[0083] Specifically, the equivalent circuit of a hybrid cascaded common-mode electromagnetic interference (EMI) filter is constructed. Based on this equivalent circuit, the common-mode current feedback suppression process of the hybrid cascaded EEM filter is analyzed. Finally, the transfer function of the hybrid cascaded EEM filter is determined based on this common-mode current feedback suppression process. .

[0084] As an example, Figure 5 The block diagram for common-mode current feedback suppression of a hybrid cascaded common-mode electromagnetic interference filter is shown below. Figure 5 It can be seen that the current I flowing into the linear stable impedance network 2 L The first filter module 11 respectively And linear stable impedance network 2 impedance The values ​​are then added together, and the sum is then passed through the admittance of the first filtering module 11. The compensation current of the first filter module 11 is obtained. The current I flowing into the linear stable impedance network 2 L Compensation current with the first filter module 11 After addition, the mixture passes through the second filter module 12. The current I flowing into the linear stable impedance network 2 L Impedance via linear stable impedance network 2 The two values ​​are added together and then passed through the admittance of the second filter module 12. The compensation current of the second filter module 12 is obtained. ; to compensate the current of the first filter module 11 Compensation current with the second filter module 12 After addition, the mixture passes through the third filter module 13. Further suppression of high-frequency common-mode electromagnetic interference signals.

[0085] As an example, the transfer function of a hybrid cascaded common-mode electromagnetic interference filter. The expression is:

[0086]

[0087] in, For the noise source impedance, For linear stable impedance network terminal impedance, This is the amplification factor of the first filtering module. This is the amplification factor of the second filtering module. For output impedance, Let be the impedance of the third filter module, and s be the Laplace operator.

[0088] Furthermore, based on the transfer function of the hybrid cascaded common-mode electromagnetic interference filter... The insertion loss of the hybrid cascaded common-mode electromagnetic interference filter can be derived. .

[0089] As an example, the insertion loss of a hybrid cascaded common-mode electromagnetic interference filter. for:

[0090]

[0091] in, For the noise source impedance, For linear stable impedance network terminal impedance, This is the amplification factor of the first filtering module. This is the amplification factor of the second filtering module. For output impedance, Let be the impedance of the third filter module, and s be the Laplace operator.

[0092] Furthermore, by comparing the insertion loss of cascaded active common-mode electromagnetic interference filters... Insertion loss of hybrid cascaded common-mode electromagnetic interference filters It can be seen that the introduction of the common-mode inductor is equivalent to increasing the amplification factor in the insertion loss expression. This effect is not only effective in the high-frequency band, but can also significantly increase the insertion loss in the mid- and low-frequency bands. This indicates that the hybrid cascaded common-mode electromagnetic interference filter effectively enhances the electromagnetic interference performance of the system over a wide frequency range.

[0093] In one example, to verify the effectiveness of the proposed hybrid cascaded common-mode electromagnetic interference filter for servo drive systems, the load impedance at both ends of the linear stable impedance network can be set. Z L Noise source impedance Z S With a standard impedance of 50 ohms, the operational amplifiers in the first and second filter modules have gains G1 and G2 set to 10, and the resistances of resistors R2 and R5 are... The capacitors C3 and C4 are connected in parallel, resulting in a capacitance of 0.1. The capacitance C5 is 0.1. The common-mode inductor L can be set. CM1 and L CM2 The inductance value is 200. The insertion loss comparison diagram of electromagnetic interference filters with different structures was obtained through simulation, as shown in the figure below. Figure 6 As shown. From Figure 6 It can be seen that, compared with individual cascaded active filters and passive filters, the hybrid filter, which uses only a smaller common-mode inductor, not only improves the insertion loss in the high-frequency band, but also enhances the electromagnetic interference suppression performance of the cascaded active filter in the mid-to-low frequency band, verifying the correctness of the theoretical derivation.

[0094] This application presents a design method for a hybrid cascaded common-mode electromagnetic interference (EMI) filter applicable to servo drive systems. By introducing a smaller passive filter to increase the amplification factor of the insertion loss function, the EMI suppression performance of the cascaded active filter in the mid-to-low frequency band can be enhanced, and a better high-frequency suppression effect can also be achieved. Higher insertion loss is achieved by cascading two active common-mode EMI filters. Through step-by-step derivation of the transfer function and insertion loss, the filtering performance of different structures is accurately quantified, ultimately proving the effectiveness of the hybrid cascaded filter in suppressing EMI over a wide frequency band. This improves the adaptability to complex electromagnetic environments and meets the filtering requirements in diverse scenarios. This application fully leverages the low-frequency compensation capability of active devices and the high-frequency suppression reliability of passive devices, while avoiding their limitations in specific frequency bands. It significantly improves the insertion loss performance over a wide frequency range and effectively reduces the overall size and weight of the filter compared to traditional passive EMI filters.

[0095] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in the accompanying drawings may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

[0096] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] Although this application has been disclosed above with reference to embodiments, it is not intended to limit this application. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of this application.

Claims

1. A design method of a hybrid cascaded common-mode electromagnetic interference filter suitable for a servo drive system, characterized by, The application relates to a hybrid cascade common-mode electromagnetic interference filter suitable for a servo driving system, a first end of a linear stable impedance network is connected to a first end of an input power supply, a second end of the linear stable impedance network is connected to a second end of the input power supply, a third end and a fourth end of the linear stable impedance network are connected to a permanent magnet servo driving system through the hybrid cascade common-mode electromagnetic interference filter suitable for the servo driving system. The hybrid cascade common-mode electromagnetic interference filter suitable for the servo driving system comprises a first filter module, a second filter module and a third filter module, a first end of the first filter module is connected to the third end of the linear stable impedance network, a second end of the first filter module is connected to the fourth end of the linear stable impedance network, a third end of the first filter module is connected to a first end of the second filter module, a fourth end of the first filter module is connected to a second end of the second filter module, a third end of the second filter module is connected to a first end of the third filter module, a fourth end of the second filter module is connected to a second end of the third filter module, a fifth end of the second filter module is grounded, a third end of the third filter module is connected to a first end of the permanent magnet servo driving system, and a fourth end of the third filter module is connected to a second end of the permanent magnet servo driving system. The design method of the hybrid cascade common-mode electromagnetic interference filter suitable for the servo driving system comprises the following steps: a first filter module is connected to an output end of a linear stable impedance network, a second filter module is connected to a current compensation end of the first filter module, and a cascade type active common-mode electromagnetic interference filter is obtained; a transfer function of the cascade type active common-mode electromagnetic interference filter is determined according to an equivalent circuit, and an insertion loss of the cascade type active common-mode electromagnetic interference filter is determined according to the transfer function of the cascade type active common-mode electromagnetic interference filter; a third filter module is connected between an input end of a permanent magnet servo driving system and a back stage of the second filter module, and a hybrid cascade common-mode electromagnetic interference filter is obtained; a transfer function of the hybrid cascade common-mode electromagnetic interference filter is determined according to an equivalent circuit, an insertion loss of the hybrid cascade common-mode electromagnetic interference filter is determined according to the transfer function of the hybrid cascade common-mode electromagnetic interference filter, and the insertion loss of the hybrid cascade common-mode electromagnetic interference filter is used to prove the electromagnetic interference suppression effectiveness of the hybrid cascade common-mode electromagnetic interference filter in a wide frequency range; Transfer function of the hybrid cascode common-mode electromagnetic interference filter The expression is: ； Insertion loss of the hybrid cascade common mode electromagnetic interference filter The expression is: ， wherein, is the noise source impedance, is the linear stable impedance network end impedance, is the amplification of the first filter module, is the amplification of the second filter module, is the output impedance, is the impedance of the third filter module, s is the Laplace operator.

2. The design method of a hybrid cascaded common-mode electromagnetic interference filter suitable for a servo drive system according to claim 1, characterized by, the first filter module is an active common-mode electromagnetic interference filter, the second filter module is an active common-mode electromagnetic interference filter, and the third filter module is a passive filter.

3. The design method of a hybrid cascaded common-mode electromagnetic interference filter suitable for a servo drive system according to claim 2, characterized by, The first filter module comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a first operational amplifier, a first end of the first capacitor is connected to a third end of a linear stable impedance network, a second end of the first capacitor is connected to a first end of the first resistor, a second end of the first resistor is connected to a first end of the first operational amplifier, a first end of the second capacitor is connected to a fourth end of the linear stable impedance network, a second end of the second capacitor is connected to the first end of the first resistor; a first end of the second resistor is grounded, a second end of the second resistor is connected to a second end of the first operational amplifier; a first end of the fourth resistor is connected to the first end of the first operational amplifier, a second end of the fourth resistor is connected to a third end of the first operational amplifier; a first end of the third resistor is connected to the third end of the first operational amplifier, a first end of the third capacitor is connected to the first end of the first capacitor, a second end of the third capacitor is connected to a second end of the third resistor; a first end of the fourth capacitor is connected to the second end of the second capacitor, a second end of the fourth capacitor is connected to the second end of the third resistor.

4. The design method of a hybrid cascaded common-mode electromagnetic interference filter suitable for a servo drive system according to claim 2, characterized by, The second filter module comprises a current transformer, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a second operational amplifier, a fifth capacitor, a first end of a first winding of the current transformer is connected to a first end of the third capacitor, a second end of the first winding of the current transformer is connected to a first end of the third filter module; a first end of a second winding of the current transformer is connected to a first end of the fourth capacitor, a second end of the second winding of the current transformer is connected to a second end of the third filter module, a first end of a third winding of the current transformer is connected to a first end of the fifth resistor, a second end of the third winding of the current transformer is connected to a second end of the fifth resistor; a first end of the sixth resistor is connected to the second end of the fifth resistor, a second end of the sixth resistor is connected to a first end of the second operational amplifier; a first end of the seventh resistor is connected to the first end of the fifth resistor, a second end of the seventh resistor is connected to a second end of the second operational amplifier; a first end of the ninth resistor is connected to the first end of the second operational amplifier, a second end of the ninth resistor is connected to a third end of the second operational amplifier; a first end of the eighth resistor is connected to the third end of the second operational amplifier, a second end of the eighth resistor is connected to a first end of the fifth capacitor, a second end of the fifth capacitor is grounded.

5. The design method of a hybrid cascaded common-mode electromagnetic interference filter suitable for a servo drive system according to claim 2, characterized by, The third filter module comprises a first inductor and a second inductor, a first end of the first inductor is connected to a second end of the first winding of the current transformer, a second end of the first inductor is connected to a first end of a permanent magnet servo drive system; a first end of the second inductor is connected to a second end of the second winding of the current transformer, a second end of the second inductor is connected to a second end of the permanent magnet servo drive system.

6. The design method of a hybrid cascaded common-mode electromagnetic interference filter suitable for use in a servo drive system according to claim 1, characterized by, Transfer function of a cascaded active common mode electromagnetic interference filter The expression for the transfer function is: wherein, is the input current to the linear stable impedance network at the end of the cascaded active common mode electromagnetic interference filter, is the common mode current source current, is the noise source impedance, is the impedance at the end of the linear stable impedance network, is the amplification factor of the first filter module, is the amplification factor of the second filter module, is the output impedance, s is the Laplace operator.

7. The design method of a hybrid cascaded common-mode electromagnetic interference filter suitable for use in a servo drive system according to claim 1, characterized by, Insertion loss of cascaded active common mode electromagnetic interference filter The expression is: wherein, is the input current at the end of the linear stable impedance network for a non-cascaded active common mode electromagnetic interference filter, is the input current at the end of the linear stable impedance network for a cascaded active common mode electromagnetic interference filter, is the noise source impedance, is the end impedance of the linear stable impedance network, is the amplification factor of the first filter module, is the amplification factor of the second filter module, is the output impedance, s is the Laplace operator.

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