Electromagnet soft-switching drive circuit

Abstract

The application discloses a kind of electromagnet soft switch driving circuit and vibration control system in the field of vibration control.The driving circuit includes bus capacitor, high-side switching device, low-side switching device, auxiliary switching device, resonant inductor, resonant capacitor, load electromagnet, auxiliary freewheeling diode, low-side freewheeling diode and high-side freewheeling diode.The two ends of resonant capacitor are respectively connected with the second end of load electromagnet and the anode of high-side freewheeling diode;the first end of resonant inductor is respectively connected with the second end of load electromagnet, the anode of low-side freewheeling diode and the first end of low-side switching device, and the second end is connected with the first end of auxiliary switching device and the cathode of low-side freewheeling diode connected through auxiliary freewheeling diode.The application reduces the voltage slope of the two ends of electromagnet, thereby reducing the overall EMI level of vibration control system, so that it has EMC performance passing through radiation and conduction test when full load.

Description

Technical Field

[0001] This invention belongs to the field of vibration control and drive circuit technology, specifically relating to an electromagnet soft-switching drive circuit and a vibration control system. Background Technology

[0002] Electromagnets are widely used in actuators of equipment such as vibrating feeding systems and vibrating platforms. The armature of an electromagnet is mounted on various mechanical structures to generate mechanical displacement. The electromagnet drive circuit needs to achieve output current adjustment and frequency variation in order to realize variable mechanical displacement amplitude and vibration frequency.

[0003] Existing electromagnet drive circuits have the problem of high voltage slope (dV / dt) across the electromagnet. In electromagnetic interference (EMI) sensitive applications, they cannot pass the EN IEC 61000-6-4 radiation and conduction tests under full-load output current conditions. Summary of the Invention

[0004] The purpose of this invention is to provide an electromagnet soft-switching drive circuit and a vibration control system to reduce the voltage slope (dV / dt) across the electromagnet, thereby reducing the overall EMI level of the vibration control system assembled from the electromagnet driver and the electromagnet, enabling it to pass the EN IEC 61000-6-4 radiation and conduction tests under full load.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, a soft-switching drive circuit for an electromagnet is provided, comprising: a bus capacitor C, a high-side switching device T1, a low-side switching device T2, an auxiliary switching device T3, a resonant inductor LX, a resonant capacitor CX, a load electromagnet L, an auxiliary freewheeling diode D, a low-side freewheeling diode D1, and a high-side freewheeling diode D2; wherein, one end of the bus capacitor C is connected to the positive terminal of the bus, and the other end is connected to the negative terminal of the bus; the first terminal P1 of the high-side switching device T1 is connected to the positive terminal of the bus and the negative terminal of the low-side freewheeling diode D1, and the second terminal P2 is connected to the negative terminal of the high-side freewheeling diode D2 and the first terminal Pin1 of the load electromagnet L; the second terminal Pin2 of the load electromagnet L is connected to the first terminal Pin1 of the resonant capacitor CX; the first terminal Pin1 of the resonant inductor LX is connected to the second terminal Pin2 of the load electromagnet L, the positive terminal of the low-side freewheeling diode D1, and the first terminal P1 of the low-side switching device T2; the resonant inductor LX... The second terminal Pin2 is connected to the first terminal P1 of the auxiliary switching device T3, and is connected to the negative terminal of the low-side freewheeling diode D1 via the auxiliary freewheeling diode D; the positive terminal of the high-side freewheeling diode D2, the second terminal Pin2 of the resonant capacitor CX, the second terminal P2 of the low-side switching device T2, and the second terminal P2 of the auxiliary switching device T3 are connected in parallel to the negative terminal of the bus. The control terminal P3 of the high-side switching device T1, the low-side switching device T2, and the auxiliary switching device T3 are used to input drive signals.

[0006] Furthermore, in the electromagnet soft-switching drive circuit, the auxiliary freewheeling diode D includes auxiliary freewheeling diode D3 and auxiliary freewheeling diode D4. The positive terminal of auxiliary freewheeling diode D4 is connected to the second terminal Pin2 of the resonant inductor LX, and the negative terminal is connected to the positive terminal of auxiliary freewheeling diode D3. The negative terminal of auxiliary freewheeling diode D3 is connected to the negative terminal of the low-side freewheeling diode D1.

[0007] Optionally, in the electromagnet soft-switching drive circuit, the high-side switching device T1, the low-side switching device T2, and the auxiliary switching device T3 are all IGBT power devices. The first terminal P1 of the high-side switching device, the low-side switching device, and the auxiliary switching device is the collector, the second terminal P2 is the emitter, and the control terminal P3 is the gate.

[0008] Optionally, in the electromagnet soft-switching drive circuit, the high-side switching device T1, the low-side switching device T2, and the auxiliary switching device T3 are all MOSFET power devices. The first terminal P1 of the high-side switching device, the low-side switching device, and the auxiliary switching device is the drain, the second terminal P2 is the source, and the control terminal P3 is the gate.

[0009] Furthermore, in the electromagnet soft-switching drive circuit, the resonant inductor LX and resonant capacitor CX reduce the falling edge voltage slope of the second terminal Pin2 of the load electromagnet L relative to the negative terminal of the bus through 1 / 4 cycle resonance. The slope calculation formula is as follows:

[0010] in, LX Let LX be the inductance of the resonant inductor. CX The capacitance of the resonant capacitor CX is... Vm This is the bus voltage.

[0011] Furthermore, in the aforementioned electromagnet soft-switching drive circuit, when the load electromagnet L acts as a constant current source to charge the resonant capacitor CX within a single modulation frequency cycle, the rising edge voltage slope of the second terminal Pin2 of the load electromagnet L relative to the negative terminal of the bus is reduced. The slope calculation formula is as follows:

[0012] in, I This represents the current in the load electromagnet L during a single modulation frequency cycle. Let be the capacitance of the resonant capacitor CX.

[0013] Furthermore, in the aforementioned electromagnet soft-switching drive circuit, when the control electrode drive signal of the auxiliary switching device T3 is in "conducting" logic, the slope of the voltage across the load electromagnet L is:

[0014] in, LX Let LX be the inductance of the resonant inductor. CX The capacitance of the resonant capacitor CX is... Vm This is the bus voltage.

[0015] Furthermore, in the aforementioned electromagnet soft-switching drive circuit, when the control electrode drive signal of the auxiliary switching device T3 is in "off" logic, the slope of the voltage across the load electromagnet L is:

[0016] in, I This represents the current in the load electromagnet L during a single modulation frequency cycle. Let be the capacitance of the resonant capacitor CX.

[0017] In a second aspect, the present invention provides a vibration control system, including the electromagnet soft-switching drive circuit described in any one of the first aspects.

[0018] Furthermore, the vibration control system can be a vibration feeding system, a vibration platform, etc.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention adopts a soft-switching modulation topology, which reduces the voltage slope (dV / dt) across the electromagnet by using a resonant capacitor and a resonant inductor, thereby reducing the overall EMI level of the electromagnet driver and the vibration control system assembled from the electromagnet. The typical voltage slope (dV / dt) of the prior art is 10V / nS, while this invention reduces the voltage slope (dV / dt) to 0.5V / nS in practical applications; (2) Compared with the existing technical solution that solves the EMI problem by connecting the power frequency dV / dt filter, the present invention does not require the installation of the power frequency dV / dt filter, thus reducing the size of the electromagnet drive circuit; since the power frequency dV / dt filter is not used, there is no copper loss or iron loss of the filter, thus improving the power conversion efficiency while solving the EMI problem of the electromagnet driver. (3) The electromagnet is connected to the electromagnet soft-switching drive circuit of the present invention by means of a cable, and has EMC (electromagnetic compatibility) performance that passes the EN IEC 61000-6-4 radiation and conduction test when the output current is fully loaded. Attached Figure Description

[0020] Figure 1 A schematic diagram of an existing electromagnet drive circuit. Figure 2 This is a schematic diagram of the overall electromagnet soft-switching drive circuit of the present invention; Figure 3 This is a schematic diagram of the electromagnet soft-switching drive circuit according to an embodiment of the present invention; Figure 4 for Figure 3 The timing diagram of the electromagnet soft-switching drive circuit is shown below. Figure 5 for Figure 3 The diagram shows the polarity of voltage and current measurement across the load electromagnet in the electromagnet soft-switching drive circuit. Figure 6 The figure shows the radiated EMI test results of the existing electromagnet drive circuit with the polarization direction perpendicular. Figure 7 The diagram shows the radiated EMI test results of an existing electromagnet drive circuit with horizontal polarization direction. Figure 8 for Figure 3 The diagram shows the radiated EMI test results of the electromagnet soft-switching drive circuit with the polarization direction perpendicular. Figure 9 for Figure 3 The diagram shows the radiated EMI test results of the electromagnet soft-switching drive circuit with the polarization direction horizontal. Detailed Implementation

[0021] The present invention will be described in more detail below with examples. These examples are merely descriptions of the best practices of the present invention and do not limit the scope of the present invention in any way.

[0022] like Figure 1 The diagram shown is a schematic of a prior art electromagnet drive circuit, which includes a bus capacitor C, a high-side switching device T1, a low-side switching device T2, a low-side freewheeling diode D1, a high-side freewheeling diode D2, and a load electromagnet L.

[0023] The high-side switching device T1 and the low-side switching device T2 can be IGBT or MOSFET power devices. Figure 1 The diagram provided shows the schematic symbol for an IGBT.

[0024] When the high-side switching device T1 and the low-side switching device T2 use MOSFET power devices, the MOSFET drain corresponds to the IGBT collector, the MOSFET source corresponds to the IGBT emitter, and the MOSFET gate corresponds to the IGBT gate.

[0025] like Figure 1 As shown, one end of the bus capacitor C is connected to the positive terminal of the bus, and the other end is connected to the negative terminal of the bus. The collector of the high-side switching device T1 is connected to the positive terminal of the bus and the negative terminal of the low-side freewheeling diode D1, respectively. The emitter of the high-side switching device T1 is connected to the negative terminal of the high-side freewheeling diode D2, and the positive terminal of the high-side freewheeling diode D2 is connected to the negative terminal of the bus. The first end Pin1 of the load electromagnet L is connected to the common terminal of the emitter of the high-side switching device T1 and the negative terminal of the high-side freewheeling diode D2. The second end Pin2 of the load electromagnet L is connected to the common terminal of the positive terminal of the low-side freewheeling diode D1 and the collector of the low-side switching device T2. The emitter of the low-side switching device T2 is connected to the positive terminal of the high-side freewheeling diode D2.

[0026] The gates of the high-side switching device T1 and the low-side switching device T2 are used to input drive signals, respectively.

[0027] right Figure 1 The electromagnet drive circuit shown was subjected to radiated EMI (electromagnetic interference) testing: Test conditions: Prepare a 1.5-meter unshielded three-core (load terminal 1, load terminal 2, protective ground PE) output cable. Connect the output cable to the load electromagnet L, and connect the electromagnet magnet to the protective ground PE. The electromagnet inductance is 300mH, and the rated current is 6A. Set the electromagnet driver output to 6A RMS and 35Hz output frequency. Conduct radiated EMI (electromagnetic interference) tests with antenna heights of 1-3 meters in an anechoic chamber conforming to the EN IEC 61000-6-4 test standard.

[0028] The radiated EMI test results of the electromagnet drive circuit perpendicular to the polarization direction are as follows: Figure 6 As shown in Table 1, the radiated EMI test results at the polarization direction level are as follows: Figure 7 As shown in Table 2.

[0029] Table 1. Radiated EMI test results of existing technologies perpendicular to the polarization direction.

[0030] Table 2. Radiated EMI test results of existing technologies at the polarization direction level.

[0031] Depend on Figure 6 , Figure 7 As can be seen from Tables 1 and 2, Figure 1 The electromagnet drive circuit shown exhibits the following results: In the test with the polarization direction perpendicular, the highest peak electric field strength reading is 59.50 dBμV / m at a frequency of 40.83 MHz and an antenna height of 1 meter, exceeding the limit of standard EN IEC 61000-6-4 by 9.50 dBμV / m. In the test with the polarization direction horizontal, the reading exceeds the limit by 3.26 dBμV / m at a frequency of 128.79 MHz. The test fails.

[0032] Figure 2 This is a schematic diagram of the overall electromagnet soft-switching drive circuit of the present invention. Figure 2 As shown, the electromagnet soft-switching drive circuit of the present invention includes: bus capacitor C, high-side switching device T1, low-side switching device T2, auxiliary switching device T3, resonant inductor LX, resonant capacitor CX, load electromagnet L, auxiliary freewheeling diode D, low-side freewheeling diode D1 and high-side freewheeling diode D2.

[0033] Among them, one end of the bus capacitor C is connected to the positive terminal of the bus, and the other end is connected to the negative terminal of the bus; The first terminal P1 of the high-side switching device T1 is connected to the positive terminal of the bus and the negative terminal of the low-side freewheeling diode D1, respectively. The second terminal P2 is connected to the negative terminal of the high-side freewheeling diode D2 and the first terminal Pin1 of the load electromagnet L. The second terminal Pin2 of the load electromagnet L is connected to the first terminal Pin1 of the resonant capacitor CX. The first terminal Pin1 of the resonant inductor LX is connected to the second terminal Pin2 of the load electromagnet L, the positive terminal of the low-side freewheeling diode D1, and the first terminal P1 of the low-side switching device T2, respectively. The second terminal Pin2 of the resonant inductor LX is connected to the first terminal P1 of the auxiliary switching device T3, and is connected to the negative terminal of the low-side freewheeling diode D1 through the auxiliary freewheeling diode D. The positive terminal of the high-side freewheeling diode D2, the second terminal Pin2 of the resonant capacitor CX, the second terminal P2 of the low-side switching device T2, and the second terminal P2 of the auxiliary switching device T3 are connected in parallel to the negative terminal of the bus. The control electrode P3 of the high-side switching device T1, the low-side switching device T2, and the auxiliary switching device T3 is used to input drive signals.

[0034] In one embodiment, the auxiliary freewheeling diode D includes auxiliary freewheeling diode D3 and auxiliary freewheeling diode D4. The anode of auxiliary freewheeling diode D4 is connected to the second terminal Pin2 of the resonant inductor LX, and the cathode is connected to the anode of auxiliary freewheeling diode D3. The cathode of auxiliary freewheeling diode D3 is connected to the cathode of the low-side freewheeling diode D1. In other embodiments, the auxiliary freewheeling diode D may include one or more auxiliary freewheeling diodes.

[0035] Among them, the high-side switching device T1, the low-side switching device T2, and the auxiliary switching device T3 can be IGBT power devices or MOSFET power devices.

[0036] When the high-side switching device T1, the low-side switching device T2, and the auxiliary switching device T3 are all IGBT power devices, the first terminal P1 of the high-side switching device, the low-side switching device, and the auxiliary switching device is the collector, the second terminal P2 is the emitter, and the control terminal P3 is the gate.

[0037] When the high-side switching device T1, the low-side switching device T2, and the auxiliary switching device T3 are all MOSFET power devices, the first terminal P1 of the high-side switching device, the low-side switching device, and the auxiliary switching device is the drain, the second terminal P2 is the source, and the control terminal P3 is the gate.

[0038] like Figure 3 As shown in the figure, an embodiment of the present invention provides an electromagnet soft-switching drive circuit, including: bus capacitor C, high-side switching device T1, low-side switching device T2, auxiliary switching device T3, resonant inductor LX, resonant capacitor CX, load electromagnet L, low-side freewheeling diode D1, high-side freewheeling diode D2, auxiliary freewheeling diode D3 and auxiliary freewheeling diode D4.

[0039] Among them, the high-side switching device T1, the low-side switching device T2, and the auxiliary switching device T3 adopt IGBT power devices. Figure 3 The schematic symbol for IGBT is given in the figure.

[0040] like Figure 3 As shown, one end of the bus capacitor C is connected to the positive terminal of the bus, and the other end is connected to the negative terminal of the bus. The collector of the high-side switching device T1 is connected to the positive terminal of the bus and the negative terminal of the low-side freewheeling diode D1, respectively. The emitter of the high-side switching device T1 is connected to the negative terminal of the high-side freewheeling diode D2, and the positive terminal of the high-side freewheeling diode D2 is connected to the negative terminal of the bus. The first terminal Pin1 of the load electromagnet L is connected to the common terminal of the emitter of the high-side switching device T1 and the negative terminal of the high-side freewheeling diode D2. The second terminal Pin2 of the load electromagnet L is connected to the first terminal Pin1 of the resonant capacitor CX. The second terminal Pin2 of the resonant capacitor CX is connected to the positive terminal of the high-side freewheeling diode D2. The first terminal Pin1 of the resonant inductor LX is connected to the second terminal Pin2 of the load electromagnet L, the positive terminal of the low-side freewheeling diode D1, and the collector of the low-side switching device T2, respectively. The second terminal Pin2 of the resonant inductor LX is connected to the negative terminal of the low-side freewheeling diode D1 through the auxiliary freewheeling diode D4 and the auxiliary freewheeling diode D3 in sequence. The emitter of the low-side switching device T2 is connected to the second terminal Pin2 of the resonant capacitor CX; The collector of the auxiliary switching device T3 is connected to the second terminal Pin2 of the resonant inductor LX, and the emitter of the auxiliary switching device T3 is connected to the emitter of the low-side switching device T2.

[0041] The gates of the high-side switching device T1, the low-side switching device T2, and the auxiliary switching device T3 are used to input drive signals.

[0042] Among them, the positive terminal of the auxiliary freewheeling diode D4 is connected to the second terminal Pin2 of the resonant inductor LX, the negative terminal of the auxiliary freewheeling diode D4 is connected to the positive terminal of the auxiliary freewheeling diode D3, and the negative terminal of the auxiliary freewheeling diode D3 is connected to the negative terminal of the low-side freewheeling diode D1.

[0043] The high-side switching device T1 and the low-side switching device T2 provide a bus current path for the charging cycle of the load electromagnet L.

[0044] The high-side freewheeling diode D2 and the low-side freewheeling diode D1 provide the bus current path for the discharge cycle of the load electromagnet L.

[0045] The bus capacitor C provides bus current for the load electromagnet L during its charging cycle. During the discharge cycle, the load electromagnet L charges the bus capacitor C, providing a current path for the load electromagnet L during its discharge cycle.

[0046] The resonant inductor LX and resonant capacitor CX reduce the falling edge voltage slope of the second terminal Pin2 of the load electromagnet L relative to the negative terminal of the bus through 1 / 4-cycle resonance. The slope is calculated using the following formula: (1) in, LXLet LX be the inductance of the resonant inductor. CX The capacitance of the resonant capacitor CX is... Vm This is the bus voltage.

[0047] Within a single modulation frequency cycle, the load electromagnet L is considered a constant current source. When charging the resonant capacitor CX, it can reduce the rising edge voltage slope of the second terminal Pin2 of the load electromagnet L relative to the negative terminal of the bus. The slope calculation formula is as follows: (2) in, I This represents the current in the load electromagnet L during a single modulation frequency cycle. CX Let be the capacitance of the resonant capacitor CX.

[0048] The operating timing sequence of the electromagnet soft-switching drive circuit in this embodiment of the invention is as follows: Figure 4 As shown in the figure. The current waveform of the load electromagnet L is only for schematic diagram of the working timing. In actual applications, it is modulated into a sine waveform using SPWM. The wavy line represents the omission of multiple identical waveform segments and repetitive working processes.

[0049] like Figure 4 As shown, this invention uses three gate drive signals for switching devices: the gate drive signal for the high-side switching device T1, the gate drive signal for the low-side switching device T2, and the gate drive signal for the auxiliary switching device T3. The microcontroller controls these three drive signals to adjust the effective value and frequency of the electromagnet current.

[0050] like Figure 4 As shown, a "single output current frequency cycle" is considered a complete timing sequence. For example, if the output current frequency needs to be set to 35Hz, then 35 "single output current frequency cycles" are executed per second. During the "load electromagnet charging cycle," the electromagnet current gradually increases, and the electromagnet magnetic field strength gradually increases. During the "load electromagnet discharging cycle," the electromagnet current gradually decreases, and the electromagnet magnetic field strength gradually decreases.

[0051] Multiple executions of a "single modulation frequency cycle (carrier frequency cycle)" are required to control the rise and fall of the current in the load electromagnet. For example, in this embodiment, a 20kHz carrier frequency is used, and the output current frequency needs to be set to 50Hz. Therefore, the "single output current frequency cycle" is 20ms. Since the carrier frequency is 20kHz, in order to meet the requirement of the "single output current frequency cycle", 400 executions of the "single modulation frequency cycle (carrier frequency cycle)" are required.

[0052] Among them, carrier frequency ( TF ), set output current frequency ( IF ), the number of "single modulation frequency cycles" required (N The three satisfy the following relationship: (3) Among them, "load electromagnet charging cycle" and "load electromagnet discharging cycle" each account for half of N.

[0053] like Figure 4 As shown, when the gate drive signal of the auxiliary switching device T3 is the "IGBT ON" logic, the slope of the voltage across the load electromagnet L is equal to the value calculated by formula (1). When the gate drive signal of the auxiliary switching device T3 is the "IGBT OFF" logic, the slope of the voltage across the electromagnet is equal to the value calculated by formula (2).

[0054] in, Figure 4 The polarity of voltage and current measurement across the medium-load electromagnet L is as follows: Figure 5 As shown.

[0055] Radiated EMI (electromagnetic interference) testing was performed on the electromagnet soft-switching drive circuit of this embodiment of the invention: Test conditions: Prepare a 1.5-meter unshielded three-core (load terminal 1, load terminal 2, protective ground PE) output cable. Connect the output cable to the load electromagnet L, and connect the electromagnet magnet to the protective ground PE. The electromagnet inductance is 300mH, and the rated current is 6A. Set the electromagnet driver output to 6A RMS value and 35Hz output frequency. Conduct radiated EMI (electromagnetic interference) tests with antenna heights of 1 meter to 3 meters in an anechoic chamber conforming to the EN IEC 61000-6-4 test standard.

[0056] The radiated EMI test results of the electromagnet soft-switching drive circuit perpendicular to the polarization direction are as follows: Figure 8 As shown in Table 3, the results of the radiated EMI test in the horizontal direction are as follows: Figure 9 As shown in Table 4.

[0057] Table 3. Radiated EMI test results of embodiments of the present invention perpendicular to the polarization direction.

[0058] Table 4. Radiated EMI test results of the embodiments of the present invention at the polarization direction level.

[0059] Depend on Figure 8 , Figure 9As shown in Tables 3 and 4, the electromagnet soft-switching drive circuit of this embodiment of the invention, in the test results with the polarization direction perpendicular, has a maximum peak electric field strength reading of 36.73 dBμV / m, a frequency of 36.61 MHz, and an antenna height of 1 meter, which is lower than the limit of standard EN IEC 61000-6-4, and the distance limit margin is 13.27 dBμV / m. In the test results with the polarization direction horizontal, no frequency exceeding the limit was found in the entire test frequency band from 30 MHz to 1 GHz, and the test is qualified.

[0060] This invention reduces the voltage slope (dV / dt) across the electromagnet by using a resonant capacitor and a resonant inductor. The typical voltage slope (dV / dt) of existing solutions is 10V / nS, while this invention reduces it to 0.5V / nS in practical applications. Connecting the electromagnet to the soft-switching drive circuit of this invention using a cable provides EMC (electromagnetic compatibility) performance that meets EN IEC 61000-6-4 radiated and conducted electromagnetic compatibility tests under full load.

[0061] In other embodiments, the present invention provides a vibration control system including the aforementioned electromagnet soft-switching drive circuit.

[0062] The vibration control system can be a vibratory feeding system, a vibratory platform, etc.

[0063] By using resonant capacitors and resonant inductors, the voltage slope (dV / dt) across the electromagnet is reduced, thereby lowering the overall EMI level of the electromagnet driver and the vibration control system assembled from the electromagnet, enabling it to achieve EMC (electromagnetic compatibility) performance that passes the EN IEC 61000-6-4 radiation and conduction tests when the output current is at full load.

[0064] The present invention has been disclosed above with reference to preferred embodiments, but it is not intended to limit the present invention. All technical solutions obtained by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the present invention.

Claims

1. A soft-switching drive circuit for an electromagnet, characterized in that, include: The system comprises a bus capacitor, a high-side switching device, a low-side switching device, an auxiliary switching device, a resonant inductor, a resonant capacitor, a load electromagnet, an auxiliary freewheeling diode, a low-side freewheeling diode, and a high-side freewheeling diode. One end of the bus capacitor is connected to the positive terminal of the bus, and the other end is connected to the negative terminal of the bus. The first end of the high-side switching device is connected to the positive terminal of the bus and the negative terminal of the low-side freewheeling diode. The second end of the high-side switching device is connected to the negative terminal of the high-side freewheeling diode and the first end of the load electromagnet. The second end of the load electromagnet is connected to the first end of the resonant capacitor. The first end of the resonant inductor is connected to the second end of the load electromagnet, the positive terminal of the low-side freewheeling diode, and the first end of the low-side switching device. The second end of the resonant inductor is connected to the first end of the auxiliary switching device and then connected to the negative terminal of the low-side freewheeling diode via the auxiliary freewheeling diode. The positive terminal of the high-side freewheeling diode, the second end of the resonant capacitor, the second end of the low-side switching device, and the second end of the auxiliary switching device are connected in parallel to the negative terminal of the bus. The control terminals of the high-side switching device, the low-side switching device, and the auxiliary switching device are used to input drive signals.

2. The electromagnet soft-switching drive circuit according to claim 1, characterized in that, The auxiliary freewheeling diode includes auxiliary freewheeling diode D3 and auxiliary freewheeling diode D4. The positive terminal of auxiliary freewheeling diode D4 is connected to the second terminal of the resonant inductor, and the negative terminal is connected to the positive terminal of auxiliary freewheeling diode D3. The negative terminal of auxiliary freewheeling diode D3 is connected to the negative terminal of the low-side freewheeling diode.

3. The electromagnet soft-switching drive circuit according to claim 1, characterized in that, The high-side switching device, low-side switching device, and auxiliary switching device are all IGBT power devices. The first terminal of the high-side switching device, low-side switching device, and auxiliary switching device is the collector, the second terminal is the emitter, and the control terminal is the gate.

4. The electromagnet soft-switching drive circuit according to claim 1, characterized in that, The high-side switching device, low-side switching device, and auxiliary switching device are all MOSFET power devices. The first terminal of the high-side switching device, low-side switching device, and auxiliary switching device is the drain, the second terminal is the source, and the control terminal is the gate.

5. The electromagnet soft-switching drive circuit according to claim 1, characterized in that, The resonant inductor and resonant capacitor reduce the falling edge voltage slope of the second terminal of the load electromagnet relative to the negative busbar through 1 / 4-cycle resonance. The formula for calculating the slope is: ； in, LX This refers to the inductance of the resonant inductor. CX This is the capacitance of the resonant capacitor. Vm This is the bus voltage.

6. The electromagnet soft-switching drive circuit according to claim 1, characterized in that, When the load electromagnet acts as a constant current source to charge the resonant capacitor within a single modulation frequency cycle, the rising edge voltage slope of the second terminal of the load electromagnet relative to the negative terminal of the bus is reduced. The formula for calculating the slope is as follows: ； in, I This refers to the current of the load electromagnet during a single modulation frequency cycle. This is the capacitance of the resonant capacitor.

7. The electromagnet soft-switching drive circuit according to claim 1, characterized in that, When the control electrode drive signal of the auxiliary switching device is in "on" logic, the slope of the voltage across the load electromagnet is: ； in, LX This refers to the inductance of the resonant inductor. CX This is the capacitance of the resonant capacitor. Vm This is the bus voltage.

8. The electromagnet soft-switching drive circuit according to claim 1, characterized in that, When the control electrode drive signal of the auxiliary switching device is in "off" logic, the slope of the voltage across the load electromagnet is: ； in, I This refers to the current of the load electromagnet during a single modulation frequency cycle. This is the capacitance of the resonant capacitor.

9. A vibration control system, characterized in that, Includes the electromagnet soft-switching drive circuit according to any one of claims 1 to 8.

10. The vibration control system according to claim 9, characterized in that, The vibration control system includes a vibration feeding system or a vibration platform.

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