Emi filter and multi-axis drive system

Abstract

The utility model discloses a kind of EMI filter and multi-axis drive system, the EMI filter includes EMI filter input end and EMI filter output end, at least one inductance is connected in series between the EMI filter input end and EMI filter output end, it is characterized by: at least one inductance is provided with the secondary side winding for connecting load, one end of secondary side winding is electrically connected with one end of load, the other end of secondary side winding is electrically connected with the other end of load.The utility model is coupled in the mode, high-frequency noise in inductance is absorbed by the pure resistance load heating of the secondary side winding, the current waveform in smoothing loop, and then reduce high-frequency leakage current.

Description

Technical Field

[0001] This utility model belongs to the field of CNC machine tool / robot technology, specifically relating to an EMI filter, a motor driver power supply system, and a multi-axis drive system. Background Technology

[0002] In the field of CNC machine tools / robotics, multi-axis drive systems serve as the core power units for CNC machine tools, machining centers, and other equipment, directly impacting machining accuracy and equipment reliability. Currently, in mainstream configurations, four-axis CNC machine tools achieve multi-face machining through x, y, and z linear axes and a single rotary axis, while five-axis systems support complex curved surface machining through dual rotary axes. With advancements in high precision, high speed, and high torque performance, multi-axis drive systems are widely used due to their energy feedback advantages. However, these systems commonly use IGBTs as drivers for switching devices. The PWM pulses output by the IGBTs in their inverter bridge generate high-order harmonics, and since power cables are the carriers of power, the harmonic hazards are amplified. At high frequencies, long cables will eventually exhibit an open-circuit state at their terminals, increasing the peak overvoltage at the motor terminals and shortening the insulation life of the motor windings. Furthermore, the impact of high common-mode voltage on the system itself and surrounding equipment is significant; the high-frequency leakage current caused by high common-mode voltage is also a factor contributing to system instability.

[0003] Currently, regarding this issue, patent publication number JP2007336634A discloses a leakage current suppression method for multi-motor drive systems, which relies on dual-axis PWM complementary control and is only applicable to even-numbered axis systems. Patent publication number CN212305187U discloses a multi-axis motor control system and method, which uses hardware synchronization signal distribution, cannot compensate for cable delay, and the duty cycle of the PWM signal is always changing during system operation. The physical distance between drive axes also causes a delay in PWM signal synchronization, so it is difficult to achieve the expected suppression effect.

[0004] Existing EMI filters are not very effective at suppressing interference. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an EMI filter, a motor driver power supply system, and a multi-axis drive system.

[0006] The technical solution of this utility model is implemented as follows: This utility model discloses an EMI filter, including an EMI filter input terminal and an EMI filter output terminal. At least one inductor is connected in series between the EMI filter input terminal and the EMI filter output terminal. The at least one inductor is provided with a secondary winding for connecting a load. One end of the secondary winding is electrically connected to one end of the load, and the other end of the secondary winding is electrically connected to the other end of the load.

[0007] Furthermore, the load is a purely resistive load.

[0008] Furthermore, when multiple inductors are connected in series between the input and output terminals of the EMI filter, only the inductor closest to the input terminal of the EMI filter is used as the secondary winding to connect the load.

[0009] Furthermore, the EMI filter of this utility model also includes a first differential mode capacitor group and a first lead-out terminal. One end of the first differential mode capacitor in the first differential mode capacitor group is electrically connected to the output terminal of the EMI filter, and the other end of the first differential mode capacitor in the first differential mode capacitor group is electrically connected to the first lead-out terminal.

[0010] Furthermore, each of the first differential mode capacitors in the first differential mode capacitor group has a first resistor connected in parallel across its terminals.

[0011] Furthermore, a first inductor and a second inductor are connected in series between the input terminal and the output terminal of the EMI filter. The input terminal of the second inductor is electrically connected to the input terminal of the EMI filter, the output terminal of the second inductor is electrically connected to the input terminal of the first inductor, and the output terminal of the first inductor is electrically connected to the output terminal of the EMI filter.

[0012] The second inductor has a secondary winding for connecting the load, one end of which is electrically connected to one end of the load, and the other end of which is electrically connected to the other end of the load.

[0013] The EMI filter also includes a second differential-mode capacitor bank and a second common-mode capacitor. One end of the second differential-mode capacitor in the second differential-mode capacitor bank is electrically connected to the output terminal of the second inductor and the input terminal of the first inductor. The other end of the second differential-mode capacitor in the second differential-mode capacitor bank is electrically connected to the second common terminal. A second resistor is connected in parallel across each of the two ends of the second differential-mode capacitor in the second differential-mode capacitor bank. One end of the second common-mode capacitor is electrically connected to the second common terminal. The other end of the second common-mode capacitor is grounded. A third resistor is connected in parallel across the two ends of the second common-mode capacitor.

[0014] And / or, it also includes a third differential mode capacitor bank, one end of the third differential mode capacitor in the third differential mode capacitor bank is electrically connected to the input terminal of the EMI filter, and the other end of the third differential mode capacitor in the third differential mode capacitor bank is electrically connected to the third common terminal.

[0015] And / or, it also includes a common-mode capacitor bank, wherein one end of the first common-mode capacitor in the common-mode capacitor bank is electrically connected to the output of the EMI filter, and the other end of the first common-mode capacitor in the common-mode capacitor bank is grounded.

[0016] This utility model also discloses a multi-axis drive system, including multiple motor drivers, a PWM rectifier unit, and an EMI filter as described above. The input terminal of the EMI filter is electrically connected to the input power supply, the output terminal of the EMI filter is electrically connected to the AC side of the PWM rectifier unit, and the DC side bus of the PWM rectifier unit is electrically connected to the motor drivers for supplying power to the motor drivers.

[0017] Furthermore, the EMI filter adopts the EMI filter described above, and the first lead of the EMI filter is electrically connected to the second lead of the DC side of the PWM rectifier unit;

[0018] The PWM rectifier unit has a first filter capacitor and a second filter capacitor connected in series between the P-terminal and the N-terminal of the bus, and the second lead is connected between the first filter capacitor and the second filter capacitor.

[0019] Furthermore, the PWM rectifier unit includes a high-frequency reactor and a power supply module. The input terminal of the high-frequency reactor is electrically connected to the output terminal of the EMI filter, and the output terminal of the high-frequency reactor is electrically connected to the AC side of the power supply module. A first filter capacitor and a second filter capacitor are connected in series between the P terminal and the N terminal of the power supply module.

[0020] Furthermore, at least one motor driver is provided with a du / dt filter between itself and the corresponding motor. The du / dt filter includes an inductor and a capacitor. The inductor is connected in series between the input terminal and the output terminal of the du / dt filter. One end of the capacitor is electrically connected to the output terminal of the du / dt filter, and the other end of the capacitor is electrically connected to a third lead. The third lead of the du / dt filter is directly or through a switch electrically connected to the first lead of the EMI filter.

[0021] Furthermore, the du / dt filter also includes a resistor, one end of which is electrically connected to the output terminal of the du / dt filter, and the other end of which is electrically connected to one end of a capacitor, and the other end of which is electrically connected to the third lead.

[0022] This invention has at least the following beneficial effects: At least one inductor is connected in series between the input and output terminals of the EMI filter. This inductor has a secondary winding for connecting a load. One end of the secondary winding is electrically connected to one end of the load, and the other end is electrically connected to the other end of the load. Through coupling, high-frequency noise in the inductor is absorbed by the heat generated by the purely resistive load connected to the secondary winding, smoothing the current waveform in the circuit and thus reducing high-frequency leakage current.

[0023] This utility model's multi-axis drive system includes an EMI filter and a PWM rectifier unit composed of a high-frequency reactor and a power supply module. The input terminal of the EMI filter is electrically connected to the input power supply, and the output terminal of the EMI filter is electrically connected to the AC side of the PWM rectifier unit. The P and N buses of the PWM rectifier unit are connected to each axis driver, and each axis driver is connected to its corresponding motor. One axis driver is connected to its corresponding motor through a du / dt filter. The communication terminal of the host computer CNC system is interconnected with the power supply module and the signal terminals of each axis driver. Using the EMI filter of this utility model, the S... X The terminal is connected to the M terminal of the power supply module, and the C terminal of the du / dt filter... R The terminal is connected to the EMI filter S through S1. X Connecting the terminals can significantly reduce the common-mode voltage in the system, extend the service life of the motor, and improve the reliable operation of the multi-axis drive system. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the EMI filter topology disclosed in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the PWM rectifier unit topology disclosed in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the du / dt filter topology disclosed in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of a multi-axis drive system provided for an embodiment of the present invention. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0030] In the description of this utility model, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this utility model, unless otherwise stated, "a plurality of" or "several" means two or more.

[0032] See Figure 1 This invention provides an EMI filter, including an EMI filter input terminal and an EMI filter output terminal. At least one inductor is connected in series between the EMI filter input terminal and the EMI filter output terminal. The at least one inductor has a secondary winding for connecting a load. One end of the secondary winding is electrically connected to one end of the load, and the other end of the secondary winding is electrically connected to the other end of the load. This invention uses coupling to absorb high-frequency noise in the second inductor through the heat generated by the purely resistive load connected to the secondary winding, smoothing the current waveform in the circuit and thus reducing high-frequency leakage current.

[0033] Furthermore, the load is a resistive load.

[0034] Furthermore, the load is a purely resistive load, i.e., a purely resistive load.

[0035] Furthermore, when multiple inductors are connected in series between the input and output terminals of the EMI filter, only the inductor closest to the input terminal of the EMI filter is used as the secondary winding to connect the load.

[0036] Furthermore, the EMI filter of this invention also includes a first differential-mode capacitor bank and a first lead-out terminal. One end of each of the first differential-mode capacitors in the first differential-mode capacitor bank is electrically connected to the output terminal of the EMI filter, and the other end of each of the first differential-mode capacitors in the first differential-mode capacitor bank is electrically connected to the first lead-out terminal Sx (i.e., the first common terminal). Furthermore, a first resistor is connected in parallel across each of the first differential-mode capacitors in the first differential-mode capacitor bank.

[0037] The number of inductors in an EMI filter can be one or more (e.g., two), depending on the requirements. EMI filters can be single-phase or three-phase. When the EMI filter is a three-phase filter, it typically has two inductors. One or more inductors are connected in series between the input and output terminals of the EMI filter. Preferably, the inductor closest to the input terminal is used to connect the secondary winding of the load.

[0038] Furthermore, when the EMI filter has only one inductor, this inductor is the first inductor, and the input terminal of the first inductor is electrically connected to the input terminal of the EMI filter.

[0039] The first inductor has a secondary winding for connecting a load, one end of which is electrically connected to one end of the load, and the other end of which is electrically connected to the other end of the load.

[0040] Furthermore, when the EMI filter has two inductors, the two inductors are a first inductor and a second inductor. The input terminal of the first inductor is electrically connected to the output terminal of the second inductor, and the input terminal of the second inductor is electrically connected to the input terminal of the EMI filter.

[0041] The second inductor has a secondary winding for connecting the load, with one end of the secondary winding electrically connected to one end of the load and the other end of the secondary winding electrically connected to the other end of the load.

[0042] When the EMI filter is a single-phase filter, it can adopt, but is not limited to, a CLC structure. In the CLC structure, the first inductor L1 is connected in series between the input and output terminals of the EMI filter. When the EMI filter is a three-phase filter, it can adopt, but is not limited to, a CLCLC structure, in which the second inductor L2 and the first inductor L1 are connected in series between the input and output terminals of the EMI filter.

[0043] If necessary, the EMI filter may also include a second inductor, with the input terminal of the first inductor electrically connected to the output terminal of the second inductor, and the input terminal of the second inductor electrically connected to the input terminal of the EMI filter.

[0044] Furthermore, the second inductor has a secondary winding for connecting the load, one end of which is electrically connected to one end of the load, and the other end of which is electrically connected to the other end of the load.

[0045] In some embodiments, the EMI filter further includes a second differential-mode capacitor bank and a second common-mode capacitor. One end of the second differential-mode capacitor in the second differential-mode capacitor bank is electrically connected to the output terminal of the second inductor and the input terminal of the first inductor. The other end of the second differential-mode capacitor in the second differential-mode capacitor bank is electrically connected to the second common terminal. A second resistor is connected in parallel across each of the two ends of the second differential-mode capacitor in the second differential-mode capacitor bank. One end of the second common-mode capacitor is electrically connected to the second common terminal. The other end of the second common-mode capacitor is grounded. A third resistor is connected in parallel across the two ends of the second common-mode capacitor.

[0046] In some embodiments, the EMI filter further includes a third differential mode capacitor bank, wherein one end of the third differential mode capacitor in the third differential mode capacitor bank is electrically connected to the input terminal of the EMI filter, and the other end of the third differential mode capacitor in the third differential mode capacitor bank is electrically connected to the third common terminal.

[0047] In some embodiments, the EMI filter further includes a common-mode capacitor bank, one end of the first common-mode capacitor in the common-mode capacitor bank is electrically connected to the output terminal of the EMI filter, and the other end of the first common-mode capacitor in the common-mode capacitor bank is grounded.

[0048] The number of differential-mode capacitors in each differential-mode capacitor bank is set as needed. The number of common-mode capacitors in each common-mode capacitor bank is set as needed. Parallel resistors can be connected across each differential-mode capacitor as needed.

[0049] In some embodiments, the first differential mode capacitor group includes three first differential mode capacitors, namely CX7, CX8, and CX9. These three first differential mode capacitors correspond to three phase lines, with one end of each capacitor electrically connected to a phase line, and the other end of each capacitor electrically connected to a first lead-out terminal Sx. The second differential mode capacitor group includes three second differential mode capacitors, namely CX4, CX5, and CX6. These three second differential mode capacitors correspond to three phase lines, with one end of each capacitor electrically connected to a phase line, and the other end of each capacitor electrically connected to a second common terminal. The third differential mode capacitor group includes three third differential mode capacitors, namely CX1, CX2, and CX3. These three third differential mode capacitors correspond to three phase lines, with one end of each capacitor electrically connected to a phase line, and the other end of each capacitor electrically connected to a third common terminal.

[0050] See Figure 1One specific embodiment discloses an EMI filter, including a second inductor L2 and a first inductor L1. The input terminals L1, L2, and L3 of the second inductor L2 are connected to one end of differential-mode capacitors CX1, CX2, and CX3, respectively. The other ends of the differential-mode capacitors CX1, CX2, and CX3 are connected as a third common terminal. The secondary windings of the second inductor L2 are Ls1 and Ls2. The output terminal of L1 is connected to the input terminal of the first inductor L2. The common terminal of L1 and L2 is connected to one end of differential-mode capacitors CX4, CX5, and CX6. The other ends of the differential-mode capacitors CX4, CX5, and CX6 are connected as a third common terminal. The second common terminal is connected to one end of the common-mode capacitor CY1 and one end of the resistor R4. The other end of the common-mode capacitor CY1 and the other end of the resistor R4 are grounded. The output terminals L1', L2', and L3' of the first inductor L1 are connected to one end of the differential-mode capacitors CX7, CX8, and CX9, respectively. The other ends of the differential-mode capacitors CX7, CX8, and CX9 are connected as the first common terminal SX. One end of the common-mode capacitors CY2, CY3, and CY4 are connected to L1', L2', and L3', respectively. The other end of the common-mode capacitors CY2, CY3, and CY4, i.e., the common terminal, is grounded.

[0051] Differential mode capacitors CX4, CX5, and CX6 are connected in parallel with resistors R1, R2, and R3, respectively. Differential mode capacitors CX7, CX8, and CX9 are connected in parallel with resistors R5, R6, and R, respectively.

[0052] See Figure 1 , Figure 2 and Figure 4 This utility model also discloses a multi-axis drive system, including multiple motor drivers, a PWM rectifier unit, and an EMI filter as described in any of the above embodiments. The input terminal of the EMI filter is electrically connected to the input power supply, and the output terminal of the EMI filter is electrically connected to the AC side of the PWM rectifier unit. The DC side bus of the PWM rectifier unit is electrically connected to the motor drivers for supplying power to the motor drivers. The P and N output power supply terminals of the power module are connected to the power supply input terminals of each motor driver, and the output terminals of the motor drivers are connected to the corresponding motors.

[0053] The first lead of the EMI filter is electrically connected to the second lead, or M-terminal, on the DC side of the PWM rectifier unit. The second lead can be, but is not limited to, connected between the two filter capacitors on the DC side of the PWM rectifier unit, so that common-mode voltage clamping is achieved after the first lead of the EMI filter is electrically connected to the second lead, or M-terminal, on the DC side of the PWM rectifier unit.

[0054] Furthermore, a first filter capacitor and a second filter capacitor are connected in series between the P-terminal and the N-terminal of the PWM rectifier unit, and the second lead is connected between the first filter capacitor and the second filter capacitor.

[0055] Furthermore, the PWM rectifier unit includes a high-frequency reactor and a power supply module. The input terminal of the high-frequency reactor is electrically connected to the output terminal of the EMI filter, and the output terminal of the high-frequency reactor is electrically connected to the AC side of the power supply module. A first filter capacitor and a second filter capacitor are connected in series between the P terminal and the N terminal of the power supply module, and a second lead is connected between the first filter capacitor and the second filter capacitor.

[0056] At least one motor driver is provided with a du / dt filter between it and the corresponding motor.

[0057] The multi-axis drive system also includes a host computer numerical control system, which is electrically connected to multiple motor drivers.

[0058] Furthermore, the du / dt filter includes an inductor and a capacitor. The inductor is connected in series between the input terminal and the output terminal of the du / dt filter. One end of the capacitor is electrically connected to the output terminal of the du / dt filter, and the other end of the capacitor is electrically connected to the third lead. The third lead of the du / dt filter is directly or through a switch electrically connected to the first lead of the EMI filter.

[0059] Furthermore, the du / dt filter adopts an LRC structure. The du / dt filter also includes a resistor, one end of which is electrically connected to the output terminal of the du / dt filter, and the other end of which is electrically connected to one end of a capacitor. The other end of the capacitor is connected to the third lead, C. R Terminal electrical connection.

[0060] Furthermore, the PWM rectifier unit also includes a controller connected to the power module (i.e., the base of the power transistor of the power module), which is connected to the host computer numerical control system.

[0061] The PWM modulation frequencies of each motor driver must be synchronized and of the same frequency, and the PWM carriers of adjacent motor drivers must be mutually exclusive.

[0062] In some embodiments, the plurality of motor drivers include an X-axis driver, a Y-axis driver, a Z-axis driver, an S-axis driver, a C-axis driver, and an A-axis driver, wherein the X-axis driver corresponds to the X-axis motor, the Y-axis driver corresponds to the Y-axis motor, the Z-axis driver corresponds to the Z-axis motor, the S-axis driver corresponds to the S-axis motor, the C-axis driver corresponds to the C-axis motor, and the A-axis driver corresponds to the A-axis motor.

[0063] When the system of this invention is applied to a CNC machine tool in a machining center, all equipment housings are connected to the grounding busbar of the machine tool housing.

[0064] During the initial power-on phase, do not connect the Sx terminal of the EMI filter to the M terminal of the power module or the C terminal of the du / dt filter. R At this point, the host computer CNC system synchronizes the PWM waveform updates between the power module and each servo driver through the communication port, and realizes the synchronization of the position loop, speed loop and current loop three-loop control between each servo driver.

[0065] The power module's P and N bus output voltages were set to 640VDC. During the machining program, the voltages of each driver's line-to-ground and line-to-line connections were tested. The A-axis driver was tested with the du / dt filter disconnected and the power cable from the driver end to the motor end being 30 meters long. The waveforms of the power module's M terminal to ground, the A-axis driver's U terminal to ground, the corresponding motor end's U terminal to ground, the EMI filter's Sx terminal to ground, the A-axis driver's UW line voltage waveform, and the corresponding motor end's UW line voltage waveform were displayed on an oscilloscope. It is evident that the excessively high common-mode voltage at the M terminal and the long power cable caused the peak-to-peak voltage of the A-axis driver's motor side to ground to exceed 2.4KV, and the motor end line voltage peak-to-peak voltage to be 2.5KV. This exceeds the motor's rated peak-to-peak voltage of 2KV (GB / T22720.1-2017 / IEC60034-18-41:2014), severely impacting the motor's lifespan.

[0066] Furthermore, the peak-to-peak voltages of M and Sx to ground are 1.28KV and 108V, respectively. Therefore, the EMI filter of this invention is introduced, connecting the Sx terminal of the EMI filter to the M terminal of the power module to achieve common-mode voltage clamping. The Ls1 and Ls2 terminals of the EMI filter are connected to an external resistor R. The C of the du / dt filter... R By connecting switch S1 to the Sx terminal of the EMI filter, the common-mode voltage waveforms of the power module M point, drive line to ground, and motor terminal line to ground were tested under the same operating conditions. The waveforms of the power module M terminal to ground, the A-axis drive U-line to ground, the corresponding motor terminal U-line to ground, the EMI filter Sx to ground, the A-axis drive UW line voltage waveform, and the corresponding motor terminal UW line voltage waveform were displayed on an oscilloscope. It can be seen that the peak-to-peak voltage amplitudes of these ports are significantly reduced and are lower than the lower limit of the motor terminal insulation withstand voltage, thereby extending the motor's service life. At the same time, the leakage current is reduced due to the resistors connected to Ls1 and Ls2 terminals (see Table 1), improving the overall reliable operation of the equipment.

[0067] Table 1

[0068]

[0069] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An EMI filter, comprising an EMI filter input terminal and an EMI filter output terminal, wherein at least one inductor is connected in series between the EMI filter input terminal and the EMI filter output terminal, characterized in that: At least one inductor has a secondary winding for connecting a load, one end of which is electrically connected to one end of the load, and the other end of which is electrically connected to the other end of the load.

2. The EMI filter as described in claim 1, characterized in that: The load is a purely resistive load.

3. The EMI filter as described in claim 1, characterized in that: When multiple inductors are connected in series between the input and output terminals of an EMI filter, only the inductor closest to the input terminal of the EMI filter is used as the secondary winding to connect the load.

4. The EMI filter as described in claim 1, characterized in that: It also includes a first differential mode capacitor group and a first lead-out terminal. One end of the first differential mode capacitor in the first differential mode capacitor group is electrically connected to the output terminal of the EMI filter, and the other end of the first differential mode capacitor in the first differential mode capacitor group is electrically connected to the first lead-out terminal.

5. The EMI filter as described in claim 4, characterized in that: Each of the first differential mode capacitors in the first differential mode capacitor group has a first resistor connected in parallel across its terminals.

6. The EMI filter as described in any one of claims 1 to 5, characterized in that: A first inductor and a second inductor are connected in series between the input and output terminals of the EMI filter. The input terminal of the second inductor is electrically connected to the input terminal of the EMI filter, the output terminal of the second inductor is electrically connected to the input terminal of the first inductor, and the output terminal of the first inductor is electrically connected to the output terminal of the EMI filter. The second inductor has a secondary winding for connecting the load, one end of which is electrically connected to one end of the load, and the other end of which is electrically connected to the other end of the load. The EMI filter also includes a second differential-mode capacitor bank and a second common-mode capacitor. One end of the second differential-mode capacitor in the second differential-mode capacitor bank is electrically connected to the output terminal of the second inductor and the input terminal of the first inductor. The other end of the second differential-mode capacitor in the second differential-mode capacitor bank is electrically connected to the second common terminal. A second resistor is connected in parallel across each of the two ends of the second differential-mode capacitor in the second differential-mode capacitor bank. One end of the second common-mode capacitor is electrically connected to the second common terminal. The other end of the second common-mode capacitor is grounded. A third resistor is connected in parallel across the two ends of the second common-mode capacitor. And / or, it also includes a third differential mode capacitor bank, one end of the third differential mode capacitor in the third differential mode capacitor bank is electrically connected to the input terminal of the EMI filter, and the other end of the third differential mode capacitor in the third differential mode capacitor bank is electrically connected to the third common terminal. And / or, it also includes a common-mode capacitor bank, wherein one end of the first common-mode capacitor in the common-mode capacitor bank is electrically connected to the output of the EMI filter, and the other end of the first common-mode capacitor in the common-mode capacitor bank is grounded.

7. A multi-axis drive system, comprising multiple motor drivers, characterized in that: It also includes a PWM rectifier unit and an EMI filter as described in any one of claims 1 to 6, wherein the input terminal of the EMI filter is electrically connected to the input power supply, the output terminal of the EMI filter is electrically connected to the AC side of the PWM rectifier unit, and the DC side bus of the PWM rectifier unit is electrically connected to the motor driver for supplying power to the motor driver.

8. The multi-axis drive system as described in claim 7, characterized in that: The first lead of the EMI filter is electrically connected to the second lead on the DC side of the PWM rectifier unit; The PWM rectifier unit has a first filter capacitor and a second filter capacitor connected in series between the P-terminal and the N-terminal of the bus, and the second lead is connected between the first filter capacitor and the second filter capacitor.

9. The multi-axis drive system as described in claim 7 or 8, characterized in that: The PWM rectifier unit includes a high-frequency reactor and a power supply module. The input terminal of the high-frequency reactor is electrically connected to the output terminal of the EMI filter, and the output terminal of the high-frequency reactor is electrically connected to the AC side of the power supply module. A first filter capacitor and a second filter capacitor are connected in series between the P terminal and the N terminal of the power supply module.

10. The multi-axis drive system as described in claim 7, characterized in that: At least one motor driver is provided with a du / dt filter between itself and the corresponding motor. The du / dt filter includes an inductor and a capacitor. The inductor is connected in series between the input terminal and the output terminal of the du / dt filter. One end of the capacitor is electrically connected to the output terminal of the du / dt filter, and the other end of the capacitor is electrically connected to a third lead. The third lead of the du / dt filter is directly or through a switch electrically connected to the first lead of the EMI filter.

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