Three-phase input filter circuit

Abstract

The utility model relates to a three-phase input filter circuit, which comprises three multi-stage filter units and three discharge units, a, B and C phases of a power supply side are respectively connected with the three-phase bridge rectification unit through the three multi-stage filtering units; the A phase, the B phase and the C phase of the power supply side are respectively connected with the N phase of the power supply side through the three multi-stage filtering units and the three discharging units; according to the utility model, the three filtering units are arranged at the input side of the three-phase power supply, the three filtering units are used for filtering the three input phases of the three-phase power supply, i.e., the A, B and C phases respectively, the current harmonic pollution at the power grid side is reduced, the reactive power is reduced, the filtering circuit is introduced at the input side, and the harmonic pollution is eliminated through the passive filtering technology. Therefore, power quality is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to power filter technical field, concretely relates to a three -phase input filter circuit. BACKGROUND

[0002] With the rapid development of modern industry and power, the electromagnetic compatibility and power quality requirement of power system are higher and higher, three -phase input power is widely used in aerospace and high -efficient power system, and electronic equipment is mostly capacitive or inductive nonlinear device, and in operation will cause grid side voltage and current waveform distortion, produces a large amount of reactive loss, and introduces a large number of harmonics to the grid, causes grid pollution, influences other equipment. SUMMARY

[0003] In order to solve the grid side voltage and current waveform distortion of power, reactive loss and grid pollution and other technical problems in the prior art, the utility model provides a three -phase input filter circuit.

[0004] The utility model solves the technical scheme of the above -mentioned technical problem as follows:

[0005] A three -phase input filter circuit, including A phase access end, B phase access end, C phase access end, N phase access end, first multistage filter unit, first discharge unit, second multistage filter unit, second discharge unit, third multistage filter unit and third discharge unit;

[0006] The A phase access end is electrically connected with one end of the first multistage filter unit, the other end of the first multistage filter unit is electrically connected with one end of the first discharge unit, and the other end of the first discharge unit is electrically connected with the N phase access end;The other end of the first multistage filter unit is used for connecting three -phase bridge rectifier unit;

[0007] The B phase access end is electrically connected with one end of the second multistage filter unit, the other end of the second multistage filter unit is electrically connected with one end of the second discharge unit, and the other end of the second discharge unit is electrically connected with the N phase access end;The other end of the second multistage filter unit is used for connecting the three -phase bridge rectifier unit;

[0008] The C phase access end is electrically connected with one end of the third multistage filter unit, the other end of the third multistage filter unit is electrically connected with one end of the third discharge unit, and the other end of the third discharge unit is electrically connected with the N phase access end;The other end of the third multistage filter unit is used for connecting the three -phase bridge rectifier unit.

[0009] The utility model discloses beneficial effect is: through setting up three filter units in the input side of three -phase power supply, utilize three filter units respectively to three input phases of three -phase power supply, namely A, B, C phase filtering, reduce the current harmonic pollution of power grid side and reduce the reactive power, introduce filter circuit in the input side, eliminate harmonic pollution through passive filter technology, thereby improve power quality.

[0010] On the basis of the above technical scheme, the utility model still can make following improvement.

[0011] Further, the first multi-stage filter unit includes a first inductor, a first resistor, a first capacitor, a second inductor, and a first transient voltage suppression diode;

[0012] The A-phase access end is electrically connected with one end of the first inductor, the other end of the first inductor is electrically connected with one end of the first resistor, the other end of the first resistor is electrically connected with one end of the first discharge unit, and two ends of the first capacitor are respectively electrically connected with two ends of the first inductor;

[0013] One end of the second inductor is electrically connected with one end of the first inductor, the other end of the second inductor is electrically connected with the other end of the first resistor, and two ends of the first transient voltage suppression diode are respectively electrically connected with two ends of the second inductor; the other end of the first resistor is used for connecting the three-phase bridge rectifying unit.

[0014] The beneficial effect of the above further scheme is that the three-phase alternating current input signal is filtered, and a filter network is formed by the inductor, the capacitor and the resistor. The high-frequency harmonic signals are filtered out by LC filtering processing of the AC input signal, and only the sine wave output of the reference frequency is reserved.

[0015] Further, the first discharge unit includes a second capacitor and a second resistor, the other end of the first resistor is electrically connected with one end of the second resistor, the other end of the second resistor is electrically connected with the N-phase access end, and two ends of the second capacitor are respectively electrically connected with two ends of the second resistor.

[0016] The beneficial effect of the above further scheme is that only LC input filtering is used, and some high-frequency harmonics are still difficult to eliminate, and electromagnetic compatibility EMC is difficult to pass, so a parallel LRC circuit is connected on the basis of the first LC filter to form a multi-stage filter circuit, some high-frequency bands are individually filtered, and higher frequency harmonics are eliminated.

[0017] Further, the second multi-stage filter unit includes a third inductor, a third resistor, a third capacitor, a fourth inductor, and a second transient voltage suppression diode;

[0018] The B-phase access end is electrically connected with one end of the third inductor, the other end of the third inductor is electrically connected with one end of the third resistor, the other end of the third resistor is electrically connected with one end of the second discharging unit, and two ends of the third capacitor are respectively electrically connected with two ends of the third inductor.

[0019] One end of the fourth inductor is electrically connected with one end of the third inductor, the other end of the fourth inductor is electrically connected with the other end of the third resistor, and two ends of the second transient voltage suppression diode are respectively electrically connected with two ends of the fourth inductor; and the other end of the third resistor is used for connecting the three-phase bridge rectifier unit.

[0020] The beneficial effect of the above further scheme is that the three-phase alternating current input signal is filtered, and a filter network is formed by the inductor, the capacitor and the resistor. The high-frequency harmonic signals in the AC input signal are filtered out through LC filtering processing, and only the sine wave of the reference frequency is retained.

[0021] Further, the second discharging unit includes a fourth capacitor and a fourth resistor, the other end of the third resistor is electrically connected with one end of the fourth resistor, the other end of the fourth resistor is electrically connected with the N-phase access end, and two ends of the fourth capacitor are respectively electrically connected with two ends of the fourth resistor.

[0022] The beneficial effect of the above further scheme is that only LC input filtering is used, and certain high-frequency harmonics are still difficult to eliminate, and electromagnetic compatibility EMC is difficult to pass, so a multi-stage filter circuit is formed by connecting the LRC circuit in parallel on the basis of the first-stage LC filter, certain high-frequency bands that are difficult to eliminate are individually filtered, and higher-frequency harmonics are eliminated.

[0023] Further, the third multi-stage filter unit includes a fifth inductor, a fifth resistor, a fifth capacitor, a sixth inductor and a third transient voltage suppression diode.

[0024] The C-phase access end is electrically connected with one end of the fifth inductor, the other end of the fifth inductor is electrically connected with one end of the fifth resistor, the other end of the fifth resistor is electrically connected with one end of the third discharging unit, and two ends of the fifth capacitor are respectively electrically connected with two ends of the fifth inductor.

[0025] One end of the sixth inductor is electrically connected with one end of the fifth inductor, the other end of the sixth inductor is electrically connected with the other end of the fifth resistor, and two ends of the third transient voltage suppression diode are respectively electrically connected with two ends of the sixth inductor; and the other end of the fifth resistor is used for connecting the three-phase bridge rectifier unit.

[0026] The beneficial effect of the above further scheme is that the three-phase alternating current input signal is filtered through an inductance, a capacitance and a resistance to form a filter network. The high-frequency noise signal is filtered out through LC filtering of the AC input signal, and only the sine wave of the reference frequency is retained.

[0027] Further, the first discharge unit comprises a sixth capacitor and a sixth resistor, one end of the sixth resistor is electrically connected to the other end of the first resistor, the other end of the sixth resistor is electrically connected to the N-phase access end, and the two ends of the sixth capacitor are respectively electrically connected to the two ends of the sixth resistor.

[0028] The beneficial effect of the above further scheme is that only LC input filtering is used, and some high-frequency harmonics are still difficult to eliminate, and electromagnetic compatibility EMC is difficult to pass, so a multi-stage filter circuit is formed by connecting an LRC circuit in parallel on the basis of the first-stage LC filter, some high-frequency bands are individually filtered, and higher-frequency harmonics are eliminated.

[0029] Further, the input filter unit comprises a seventh capacitor, an eighth capacitor and a ninth capacitor; one end of the seventh capacitor is electrically connected to the A-phase access end, the other end of the seventh capacitor is electrically connected to the N-phase access end, one end of the eighth capacitor is electrically connected to the B-phase access end, the other end of the eighth capacitor is electrically connected to the N-phase access end, one end of the ninth capacitor is electrically connected to the C-phase access end, and the other end of the ninth capacitor is electrically connected to the N-phase access end.

[0030] The beneficial effect of the above further scheme is that the seventh capacitor, the eighth capacitor and the ninth capacitor are connected between the A-phase access end and the N-phase access end, between the B-phase access end and the N-phase access end, and between the C-phase access end and the N-phase access end, respectively, to filter the A-phase, the B-phase and the C-phase of the power grid side.

[0031] Further, the three-phase bridge rectifier unit comprises a first diode, a first MOS tube, a second diode, a second MOS tube, a third diode, a third MOS tube, a fourth diode, a fourth MOS tube, a fifth diode, a fifth MOS tube, a sixth diode, a sixth MOS tube, a first rectifier output end and a second rectifier output end.

[0032] The other end of the first multi-stage filter unit is respectively electrically connected to the anode of the first diode and the drain of the second MOS tube, the cathode of the first diode is electrically connected to the source of the first MOS tube, and the drain of the first MOS tube is electrically connected to the first rectifier output end; the source of the second MOS tube is electrically connected to the cathode of the second diode, and the anode of the second diode is electrically connected to the second rectifier output end.

[0033] The other end of the second multi-stage filter unit is electrically connected with the anode of the third diode and the drain of the fourth MOS tube respectively, the cathode of the third diode is electrically connected with the source of the third MOS tube, and the drain of the third MOS tube is electrically connected with the first rectification output end; the source of the fourth MOS tube is electrically connected with the cathode of the fourth diode, and the anode of the fourth diode is electrically connected with the second rectification output end.

[0034] The other end of the third multi-stage filter unit is electrically connected with the anode of the fifth diode and the drain of the sixth MOS tube respectively, the cathode of the fifth diode is electrically connected with the source of the fifth MOS tube, and the drain of the fifth MOS tube is electrically connected with the first rectification output end; the source of the sixth MOS tube is electrically connected with the cathode of the sixth diode, and the anode of the sixth diode is electrically connected with the second rectification output end.

[0035] The beneficial effect of the above further scheme is that the three-phase bridge rectification unit can convert three-phase power output by a power grid into two-phase or single-phase current and output through two rectification output ends.

[0036] In order to solve the above technical problems, the utility model also provides a three-phase input power supply, and its specific technical contents are as follows:

[0037] A three-phase input power supply comprises the three-phase input filter circuit. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 It is the circuit principle drawing of the three-phase input filter circuit in the utility model embodiment. DETAILED DESCRIPTION

[0039] The principles and characteristics of the utility model are described below in combination with the drawings, and the examples are only used to explain the utility model and are not used to limit the scope of the utility model.

[0040] As shown in the drawings, Figure 1 The utility model provides a three-phase input filter circuit, which comprises an A-phase access end, a B-phase access end, a C-phase access end, an N-phase access end, a first multi-stage filter unit, a first discharge unit, a second multi-stage filter unit, a second discharge unit, a third multi-stage filter unit and a third discharge unit; wherein the A-phase access end is used for accessing an A-phase of a three-phase power grid, the B-phase access end is used for accessing a B-phase of the three-phase power grid, the C-phase access end is used for accessing a C-phase of the three-phase power grid, and the N-phase access end is used for accessing a neutral line or a zero line of the three-phase power grid.

[0041] The A-phase access end is electrically connected with one end of the first multi-stage filter unit, the other end of the first multi-stage filter unit is electrically connected with one end of the first discharge unit, the other end of the first discharge unit is electrically connected with the N-phase access end; the other end of the first multi-stage filter unit is used for connecting the three-phase bridge rectification unit.

[0042] The B-phase access end is electrically connected with one end of the second multi-stage filter unit, the other end of the second multi-stage filter unit is electrically connected with one end of the second discharge unit, the other end of the second discharge unit is electrically connected with the N-phase access end; the other end of the second multi-stage filter unit is used for connecting the three-phase bridge rectification unit.

[0043] The C-phase access end is electrically connected with one end of the third multi-stage filter unit, the other end of the third multi-stage filter unit is electrically connected with one end of the third discharge unit, the other end of the third discharge unit is electrically connected with the N-phase access end; the other end of the third multi-stage filter unit is used for connecting the three-phase bridge rectification unit.

[0044] By setting three filter units on the input side of the three-phase power supply, the three filter units are used to filter the three input phases A, B and C of the three-phase power supply respectively, to reduce the harmonic pollution of the grid side current and reduce the reactive power, introduce a filter circuit on the input side, eliminate harmonic pollution through passive filtering technology, and thus improve the power supply quality.

[0045] In some embodiments, the first multi-stage filter unit includes a first inductor L1, a first resistor R1, a first capacitor C1, a second inductor L2 and a first transient voltage suppression diode Z1.

[0046] The A-phase access end is electrically connected with one end of the first inductor L1, the other end of the first inductor L1 is electrically connected with one end of the first resistor R1, the other end of the first resistor R1 is electrically connected with one end of the first discharge unit, and the two ends of the first capacitor C1 are respectively electrically connected with the two ends of the first inductor L1.

[0047] One end of the second inductor L2 is electrically connected with one end of the first inductor L1, the other end of the second inductor L2 is electrically connected with the other end of the first resistor R1, and the two ends of the first transient voltage suppression diode Z1 are respectively electrically connected with the two ends of the second inductor L2; the other end of the first resistor R1 is used for connecting the three-phase bridge rectification unit.

[0048] The three-phase alternating current input signal is filtered, and a filter network is formed by inductors, capacitors and resistors. The high-frequency harmonic signals in the AC input signal are filtered out through LC filtering processing, and only the sinusoidal wave of the reference frequency is output.

[0049] In some embodiments, the first discharging unit comprises a second capacitor C2 and a second resistor R2, one end of the second resistor R2 is electrically connected with the other end of the first resistor R1, the other end of the second resistor R2 is electrically connected with the N-phase access end, and two ends of the second capacitor C2 are respectively electrically connected with two ends of the second resistor R2.

[0050] Only using LC input filter, some high frequency harmonics are still difficult to eliminate, and electromagnetic compatibility EMC is difficult to pass, therefore, on the basis of the first-stage LC filter, a parallel LRC circuit is connected to form a multi-stage filter circuit, some high frequency bands are difficult to eliminate and are filtered separately, and higher frequency harmonics are eliminated.

[0051] In some embodiments, the second multi-stage filter unit comprises a third inductor L3, a third resistor R3, a third capacitor C3, a fourth inductor L4, and a second transient voltage suppression diode Z2.

[0052] The B-phase access end is electrically connected with one end of the third inductor L3, the other end of the third inductor L3 is electrically connected with one end of the third resistor R3, the other end of the third resistor R3 is electrically connected with one end of the second discharging unit, and two ends of the third capacitor C3 are respectively electrically connected with two ends of the third inductor L3.

[0053] One end of the fourth inductor L4 is electrically connected with one end of the third inductor L3, the other end of the fourth inductor L4 is electrically connected with the other end of the third resistor R3, and two ends of the second transient voltage suppression diode Z2 are respectively electrically connected with two ends of the fourth inductor L4; and the other end of the third resistor R3 is used for connecting the three-phase bridge rectifier unit.

[0054] The three-phase alternating current input signal is filtered through an inductor, a capacitor and a resistor to form a filter network. The high-frequency harmonic signals in the AC input signal are filtered out through LC filtering processing, and only the sinusoidal wave of the reference frequency is retained.

[0055] In some embodiments, the second discharging unit comprises a fourth capacitor C4 and a fourth resistor R4, the other end of the third resistor R3 is electrically connected with one end of the fourth resistor R4, the other end of the fourth resistor R4 is electrically connected with the N-phase access end, and two ends of the fourth capacitor C4 are respectively electrically connected with two ends of the fourth resistor R4.

[0056] Only using LC input filter, some high frequency harmonics are still difficult to eliminate, and electromagnetic compatibility EMC is difficult to pass, therefore, on the basis of the first-stage LC filter, a parallel LRC circuit is connected to form a multi-stage filter circuit, some high frequency bands are difficult to eliminate and are filtered separately, and higher frequency harmonics are eliminated.

[0057] In some embodiments, the third multi-stage filter unit comprises a fifth inductor L5, a fifth resistor R5, a fifth capacitor C5, a sixth inductor L5, and a third transient voltage suppression diode Z3.

[0058] The C-phase access end is electrically connected to one end of the fifth inductor L5, the other end of the fifth inductor L5 is electrically connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is electrically connected to one end of the third discharge unit, and the two ends of the fifth capacitor C5 are respectively electrically connected to the two ends of the fifth inductor L5.

[0059] One end of the sixth inductor L5 is electrically connected to one end of the fifth inductor L5, the other end of the sixth inductor L5 is electrically connected to the other end of the fifth resistor R5, and the two ends of the third transient voltage suppression diode Z3 are respectively electrically connected to the two ends of the sixth inductor L5; the other end of the fifth resistor R5 is used to connect the three-phase bridge rectifier unit.

[0060] The three-phase alternating current input signal is filtered by an inductor, a capacitor and a resistor to form a filter network. The AC input signal is filtered by LC filtering to filter out high-frequency noise signals and only retain sinusoidal waves of the reference frequency.

[0061] In some embodiments, the first discharge unit comprises a sixth capacitor C6 and a sixth resistor R6, the other end of the first resistor R1 is electrically connected to one end of the sixth resistor R6, the other end of the sixth resistor R6 is electrically connected to the N-phase access end, and the two ends of the sixth capacitor C6 are respectively electrically connected to the two ends of the sixth resistor R6.

[0062] Only LC input filtering, some high-frequency harmonics are still difficult to eliminate, and electromagnetic compatibility EMC is difficult to pass, so a parallel LRC circuit is added on the basis of the first-stage LC filtering to form a multi-stage filtering circuit, which can filter some high-frequency bands that are difficult to eliminate and eliminate higher-frequency harmonics.

[0063] In some embodiments, the three-phase input filter circuit further comprises an input filter unit, the input filter unit comprises a seventh capacitor C7, an eighth capacitor C8 and a ninth capacitor C9; one end of the seventh capacitor C7 is electrically connected to the A-phase access end, the other end of the seventh capacitor C7 is electrically connected to the N-phase access end, one end of the eighth capacitor C8 is electrically connected to the B-phase access end, the other end of the eighth capacitor C8 is electrically connected to the N-phase access end, one end of the ninth capacitor C9 is electrically connected to the C-phase access end, and the other end of the ninth capacitor C9 is electrically connected to the N-phase access end.

[0064] By connecting capacitors between the A-phase access end and the N-phase access end, between the B-phase access end and the N-phase access end, and between the C-phase access end and the N-phase access end, respectively, the seventh capacitor C7, the eighth capacitor C8, and the ninth capacitor C9 can be used to filter the A-phase, the B-phase, and the C-phase of the power grid side, respectively.

[0065] In some embodiments, the three-phase bridge rectification unit includes a first diode D1, a first MOS tube Q1, a second diode D2, a second MOS tube Q2, a third diode D3, a third MOS tube Q3, a fourth diode D4, a fourth MOS tube Q4, a fifth diode D5, a fifth MOS tube Q5, a sixth diode D6, a sixth MOS tube Q6, a first rectification output end, and a second rectification output end.

[0066] The other end of the first multi-stage filter unit is electrically connected to the anode of the first diode D1 and the drain of the second MOS tube Q2, the cathode of the first diode D1 is electrically connected to the source of the first MOS tube Q1, and the drain of the first MOS tube Q1 is electrically connected to the first rectification output end; the source of the second MOS tube Q2 is electrically connected to the cathode of the second diode D2, and the anode of the second diode D2 is electrically connected to the second rectification output end.

[0067] The other end of the second multi-stage filter unit is electrically connected to the anode of the third diode D3 and the drain of the fourth MOS tube Q4, the cathode of the third diode D3 is electrically connected to the source of the third MOS tube Q3, and the drain of the third MOS tube Q3 is electrically connected to the first rectification output end; the source of the fourth MOS tube Q4 is electrically connected to the cathode of the fourth diode D4, and the anode of the fourth diode D4 is electrically connected to the second rectification output end.

[0068] The other end of the third multi-stage filter unit is electrically connected to the anode of the fifth diode D5 and the drain of the sixth MOS tube Q6, the cathode of the fifth diode D5 is electrically connected to the source of the fifth MOS tube Q5, and the drain of the fifth MOS tube Q5 is electrically connected to the first rectification output end; the source of the sixth MOS tube Q6 is electrically connected to the cathode of the sixth diode D6, and the anode of the sixth diode D6 is electrically connected to the second rectification output end.

[0069] The three-phase bridge rectification unit can convert three-phase power output by the power grid into two-phase current and output through the two rectification output ends.

[0070] The utility model discloses an embodiment carries out filtering to three -phase alternating current input signal, and forms filter network through inductance, capacitance and resistance group. Through the LC filtering processing to AC input signal, filter the high frequency of the signal of the clutter in it, only keep the sine wave output of reference frequency. In actual engineering, only adopt LC input filter, and the harmonic of some high frequency band is still very difficult to eliminate, and EMC is very difficult to pass through, and therefore on the basis of primary LC filter is in parallel LRC circuit, forms multistage filter circuit, and the harmonic of some high frequency band is difficult to eliminate and is filtered separately, and the harmonic of higher frequency band is eliminated.

[0071] In some other embodiments, a three-phase input power supply is also provided, which includes the three-phase input filter circuit described above. The three-phase input power supply outputs two-phase rectified current from the first and second rectified output terminals after rectifying three-phase power by the three-phase bridge rectifying unit. The gate of each MOS tube in the three-phase bridge rectifying unit is controlled by the control circuit or controller built-in the power supply to control the on-off timing of each MOS tube, so as to realize the conversion of three-phase power into two-phase output.

[0072] The above is only the preferred embodiment of the utility model, and does not limit the utility model, and any modification, equivalent replacement, improvement, etc. within the concept and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A three-phase input filter circuit, characterized by: The first multi-stage filter unit, the first discharge unit, the second multi-stage filter unit, the second discharge unit, the third multi-stage filter unit, and the third discharge unit are connected in series. The A-phase access end is electrically connected to one end of the first multi-stage filter unit, the other end of the first multi-stage filter unit is electrically connected to one end of the first discharge unit, the other end of the first discharge unit is electrically connected to the N-phase access end, and the other end of the first multi-stage filter unit is used for connecting the three-phase bridge rectifier unit. The B-phase access end is electrically connected to one end of the second multi-stage filter unit, the other end of the second multi-stage filter unit is electrically connected to one end of the second discharge unit, the other end of the second discharge unit is electrically connected to the N-phase access end, and the other end of the second multi-stage filter unit is used for connecting the three-phase bridge rectifier unit. The C-phase access end is electrically connected to one end of the third multi-stage filter unit, the other end of the third multi-stage filter unit is electrically connected to one end of the third discharge unit, the other end of the third discharge unit is electrically connected to the N-phase access end, and the other end of the third multi-stage filter unit is used for connecting the three-phase bridge rectifier unit. The first multi-stage filter unit comprises a first inductor, a first resistor, a first capacitor, a second inductor, and a first transient voltage suppression diode.

2. The three-phase input filter circuit of claim 1, wherein: The A-phase access end is electrically connected to one end of the first inductor, the other end of the first inductor is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to one end of the first discharge unit, and the two ends of the first capacitor are respectively electrically connected to the two ends of the first inductor. One end of the second inductor is electrically connected to one end of the first inductor, the other end of the second inductor is electrically connected to the other end of the first resistor, the two ends of the first transient voltage suppression diode are respectively electrically connected to the two ends of the second inductor, and the other end of the first resistor is used for connecting the three-phase bridge rectifier unit. The first discharge unit comprises a second capacitor and a second resistor, the other end of the first resistor is electrically connected to one end of the second resistor, the other end of the second resistor is electrically connected to the N-phase access end, and the two ends of the second capacitor are respectively electrically connected to the two ends of the second resistor.

3. The three-phase input filter circuit of claim 2, wherein: The second multi-stage filter unit comprises a third inductor, a third resistor, a third capacitor, a fourth inductor, and a second transient voltage suppression diode.

4. The three-phase input filter circuit of claim 1, wherein: The B-phase access end is electrically connected to one end of the third inductor, the other end of the third inductor is electrically connected to one end of the third resistor, the other end of the third resistor is electrically connected to one end of the second discharge unit, and the two ends of the third capacitor are respectively electrically connected to the two ends of the third inductor. One end of the fourth inductor is electrically connected to one end of the third inductor, the other end of the fourth inductor is electrically connected to the other end of the third resistor, the two ends of the second transient voltage suppression diode are respectively electrically connected to the two ends of the fourth inductor, and the other end of the third resistor is used for connecting the three-phase bridge rectifier unit. ​ 5. The three-phase input filter circuit of claim 4, wherein: The second discharging unit comprises a fourth capacitor and a fourth resistor, the other end of the third resistor is electrically connected with one end of the fourth resistor, the other end of the fourth resistor is electrically connected with the N-phase access end, and the two ends of the fourth capacitor are electrically connected with the two ends of the fourth resistor respectively.

6. The three-phase input filter circuit of claim 1, wherein: The third multi-stage filter unit comprises a fifth inductor, a fifth resistor, a fifth capacitor, a sixth inductor and a third transient voltage suppression diode. The C-phase access end is electrically connected with one end of the fifth inductor, the other end of the fifth inductor is electrically connected with one end of the fifth resistor, the other end of the fifth resistor is electrically connected with one end of the third discharging unit, and the two ends of the fifth capacitor are electrically connected with the two ends of the fifth inductor respectively. One end of the sixth inductor is electrically connected with one end of the fifth inductor, the other end of the sixth inductor is electrically connected with the other end of the fifth resistor, and the two ends of the third transient voltage suppression diode are electrically connected with the two ends of the sixth inductor respectively; and the other end of the fifth resistor is used for connecting the three-phase bridge rectifying unit.

7. The three-phase input filter circuit of claim 6, wherein: The first discharging unit comprises a sixth capacitor and a sixth resistor, the other end of the first resistor is electrically connected with one end of the sixth resistor, the other end of the sixth resistor is electrically connected with the N-phase access end, and the two ends of the sixth capacitor are electrically connected with the two ends of the sixth resistor respectively.

8. The three-phase input filter circuit of claim 1, wherein: The input filter unit comprises a seventh capacitor, an eighth capacitor and a ninth capacitor; one end of the seventh capacitor is electrically connected with the A-phase access end, the other end of the seventh capacitor is electrically connected with the N-phase access end, one end of the eighth capacitor is electrically connected with the B-phase access end, the other end of the eighth capacitor is electrically connected with the N-phase access end, one end of the ninth capacitor is electrically connected with the C-phase access end, and the other end of the ninth capacitor is electrically connected with the N-phase access end.

9. The three-phase input filter circuit of claim 1, wherein: The three-phase bridge rectifying unit comprises a first diode, a first MOS tube, a second diode, a second MOS tube, a third diode, a third MOS tube, a fourth diode, a fourth MOS tube, a fifth diode, a fifth MOS tube, a sixth diode, a sixth MOS tube, a first rectifying output end and a second rectifying output end. The other end of the first multi-stage filter unit is electrically connected with the anode of the first diode and the drain of the second MOS tube respectively, the cathode of the first diode is electrically connected with the source of the first MOS tube, the drain of the first MOS tube is electrically connected with the first rectifying output end; the source of the second MOS tube is electrically connected with the cathode of the second diode, and the anode of the second diode is electrically connected with the second rectifying output end. The other end of the second multi-stage filter unit is electrically connected with the anode of the third diode and the drain of the fourth MOS tube respectively, the cathode of the third diode is electrically connected with the source of the third MOS tube, the drain of the third MOS tube is electrically connected with the first rectifying output end; the source of the fourth MOS tube is electrically connected with the cathode of the fourth diode, and the anode of the fourth diode is electrically connected with the second rectifying output end. The other end of the third multi-stage filter unit is electrically connected with the anode of the fifth diode and the drain of the sixth MOS tube respectively, the cathode of the fifth diode is electrically connected with the source of the fifth MOS tube, and the drain of the fifth MOS tube is electrically connected with the first rectification output end; the source of the sixth MOS tube is electrically connected with the cathode of the sixth diode, and the anode of the sixth diode is electrically connected with the second rectification output end.

10. A three-phase input power supply characterized by: A three-phase input filter circuit comprising any one of claims 1 to 9.

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