DC system anti-rebound interference power filter

Abstract

The present invention belongs to the field of electromagnetic compatibility, and relates to an anti-rebound interference power supply filter for suppressing the counter-interference generated by the current surge during the operation of electrical equipment with high-power IGBT elements as the core on the DC power bus. It is mainly used in the DC power supply system of Dongfeng diesel locomotives to suppress the counter-interference generated by the current surge during the operation of the air-conditioning inverter connected to the locomotive power bus on the bus, and improve the reliability and safety of other electrical equipment in the same power bus. The power supply filter includes: a group of π-type low-frequency filter circuits for suppressing electromagnetic interference of low-frequency components, a group of fourth-order Butterworth high-frequency filter circuits for suppressing electromagnetic interference of medium and high-frequency components, and a group of RDC damping absorption circuits with redundancy for suppressing high-amplitude DC current surges. The low-frequency filter circuit and high-frequency filter circuit of the present invention adopt a fully balanced circuit structure, so that the surge of counter-interference can be suppressed when it is connected to the bus from the positive terminal or the negative terminal.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic compatibility, and specifically relates to a DC system anti-reverse interference power supply filter which effectively suppresses reverse counter-attack interference on a DC power supply bus caused by current surges associated with the operation of electrical equipment with high-power IGBT elements as the core. Background Art

[0002] In the same DC power supply system, as long as there is a high-power IGBT converter in the electrical equipment connected to the power bus, the current surge associated with the switching of the IGBT will cause serious reverse counter-interference to the DC power bus. According to the principle of electromagnetic compatibility, due to counter-interference, from the power access end of the power bus to the IGBT converter access end, the voltage amplitude of the interference wave will gradually increase with the change of the bus position. Close to the converter access end, the amplitude of the interference wave will be extremely large, and in serious cases, it will affect other electronic equipment connected to the bus.

[0003] Dongfeng locomotives use AC-DC drive mode, and the DC bus voltage is 110V. When the air-conditioning inverter connected to the bus is running, the accompanying DC current surge will cause counter-interference to the locomotive power bus. Especially for locomotives that have been running for a long time, counter-interference will cause other electronic equipment on the locomotive to work abnormally. In the most serious case, it will cause the locomotive to stop urgently midway. This kind of counter-interference exists not only in Dongfeng locomotives using DC bus, but also in systems using AC bus. Summary of the invention

[0004] The purpose of the present invention is to solve the counter-interference and provide a DC system anti-counter-interference power supply filter. The technical solution adopted by the present invention is as follows:

[0005] The DC system anti-counter-interference power supply filter described in the present invention is for filtering a counter-interference wave with an interference path of equipment → power supply. The counter-interference wave is different from the natural interference wave. The counter-interference wave is a continuous mode electromagnetic surge wave; the natural interference wave is an occasional high-frequency electromagnetic surge wave, and the interference path of the natural interference wave is usually from power supply → load.

[0006] The DC system anti-counterattack interference power supply filter described in the present invention includes: a group of π-type low-frequency power supply filter circuit modules with a fully balanced circuit structure mainly for suppressing low-frequency component electromagnetic interference, a group of high-frequency power supply filter circuit modules with a fully balanced circuit structure of a fourth-order Butterworth low-pass filter circuit mainly for suppressing medium- and high-frequency component electromagnetic interference, and a group of RDC damping absorption circuit modules with redundancy technology mainly for suppressing high-amplitude DC current surges; the low-frequency power supply filter circuit module and the high-frequency power supply filter circuit module are connected in series and then connected in parallel with the RDC damping absorption circuit module.

[0007] The π-type low-frequency power supply filter circuit module of the fully balanced circuit structure is composed of two groups of capacitor filter circuits and a low-frequency inductor of the fully balanced circuit structure. Each group of capacitor filter circuits is composed of an electrolytic capacitor and a non-polar high-frequency capacitor in parallel. The low-frequency inductor of the fully balanced circuit structure is composed of two groups of completely identical coils, which are respectively connected in series with the positive and negative power bus main circuits. The two groups of capacitor filter circuits are respectively connected in parallel between the two ends of the external leads of the low-frequency inductor of the fully balanced circuit structure.

[0008] The high-frequency power supply filter circuit module is composed of a fourth-order Butterworth low-pass filter circuit with a fully balanced circuit structure, wherein the fourth-order Butterworth low-pass filter circuit is composed of two levels of mutually related second-order Butterworth low-pass filter circuits connected in series, and each level of the second-order Butterworth low-pass filter circuit adopts a fully balanced circuit structure.

[0009] The first-stage filter circuit of the fourth-order Butterworth low-pass filter circuit with a fully balanced circuit structure is composed of a main high-frequency inductor with a fully balanced circuit structure and a non-polar high-frequency capacitor. The main high-frequency inductor is composed of two groups of completely identical coils. The two groups of coils of the main high-frequency inductor are respectively connected in series with the positive and negative power busbars, and the main high-frequency filter capacitor is connected in parallel between the outer leads of the two groups of coils.

[0010] The inductor of the second-stage filter circuit of the fourth-order Butterworth low-pass filter circuit of the fully balanced circuit structure is composed of two independent auxiliary inductors with the same parameters and a non-polar auxiliary high-frequency capacitor. The two independent auxiliary inductors with the same parameters are respectively connected in series with the positive and negative power bus bars, and the non-polar auxiliary high-frequency capacitor is connected in parallel to the outer ends of the two auxiliary inductors.

[0011] The fourth-order Butterworth low-pass filter circuit of the fully balanced circuit structure is a combination of two-stage mutually related second-order Butterworth low-pass filter circuits connected in series.

[0012] The RDC damping absorption circuit module with redundant design mainly for suppressing high-amplitude DC current surge is composed of a high-power resistor and an anti-surge unidirectional transient suppression diode in parallel, and the cathode of the transient suppression diode faces the positive side of the power bus, and the anode of the transient suppression diode faces the negative side of the power bus; the parallel circuit is then connected in series with a capacitor to form an RDC damping absorption circuit.

[0013] The RDC damping absorption circuit module with redundant design mainly for suppressing high-amplitude DC current surges is composed of two groups of RDC damping absorption circuits connected in parallel to form a dual-group redundant structure mode, wherein any one group can bear the energy absorption of suppressing high-amplitude DC current surges in a single-group working mode, and the two-group redundant design can make the RDC damping absorption safer and more reliable.

[0014] The high-frequency main inductor and the high-frequency auxiliary inductor in the filter circuit module are both composed of a double E-shaped magnetic core and a coil, and the low-frequency inductor is composed of a double E-shaped iron core and a coil, and the double E-shaped combined end surface is designed with a large air gap.

[0015] The π-type low-frequency power supply filter circuit module of the fully balanced circuit structure and the high-frequency power supply filter circuit module of the fourth-order Butterworth low-pass filter circuit of the fully balanced circuit structure of the present invention process the entire spectrum of the interference wave through appropriate frequency division between the two groups of modules, and the frequency division point is set according to the frequency response characteristics of the magnetic core inductor and the characteristics of the frequency response of the iron core inductor for balanced processing, for example 10kHz, and the surge interference wave above the frequency division point is effectively suppressed by the high-frequency power supply filter circuit module of the fourth-order Butterworth low-pass filter circuit of the fully balanced circuit structure mainly for suppressing the electromagnetic interference of the medium and high frequency components, and the surge interference wave below the frequency division point is suppressed by the π-type low-frequency power supply filter circuit module of the fully balanced circuit structure mainly for suppressing the electromagnetic interference of the low-frequency components after the interference wave passes through the high-frequency power supply filter circuit module.

[0016] The low-frequency inductor in the π-type low-frequency power supply filter circuit module with a fully balanced circuit structure mainly for suppressing low-frequency electromagnetic interference adopts an E-shaped silicon steel sheet core. The high magnetic permeability coefficient of the E-shaped silicon steel sheet core is more effective in blocking low-frequency interference waves. In order to adapt to working in a DC environment, the combined end surface of the E-shaped silicon steel sheet core is specially designed with a larger magnetic gap.

[0017] The high-frequency inductor in the high-frequency power supply filter circuit module of the fourth-order Butterworth low-pass filter circuit with a fully balanced circuit structure mainly for suppressing electromagnetic interference of medium and high frequency components adopts a special extended E-shaped soft magnetic material core. The E-shaped soft magnetic material core has good frequency responsiveness and is more effective against medium and high frequency interference. In order to adapt to working in a DC environment, the combined end surface of the E-shaped soft magnetic material core is specially designed with a larger magnetic gap.

[0018] The filter described in the present invention is a special anti-rebound interference DC power supply filter that is innovatively designed specifically to improve the serious counter-rebound interference generated by the operation of the locomotive air conditioner. Therefore, the safety and reliability of the inductor in the filter design under continuous surge impact under DC conditions is an important design indicator of the present invention. The filter inductor design in the present invention is different from the design of the traditional filter. Not only is there a larger air gap in the double E-shaped combined end face design, but the effective volume and cross-section of the magnetic core are also fully increased, ensuring the safety and reliability of the filter under continuous DC surge impact.

[0019] Beneficial effects:

[0020] The filtering of the counter-interference wave by the DC system anti-counter-interference power supply filter is achieved in this way.

[0021] The essence of the counter-attack interference is the interference caused by the DC high-power current surge counter-attack into the power bus. When the locomotive air-conditioning inverter is running, the DC current surge counter-attack interference to the bus enters the filter, and the RDC damping absorption circuit module of the filter is the first to bear the impact of the counter-attack surge. During the surge impact, the RDC absorption circuit absorbs the surge energy through the RDC circuit. If the transient positive voltage of the surge wave is higher than the bus voltage amplitude and lower than (transient suppression diode reverse breakdown threshold voltage + bus power supply voltage), for example 220V, the surge energy is charged and stored in the capacitor C through the resistor R in the RDC damping circuit. If the transient positive voltage of the surge wave is higher than (transient suppression diode reverse breakdown threshold voltage + bus power supply voltage), the RDC damping circuit will charge the capacitor C. For example, for a 220V bus voltage (voltage + bus power supply voltage), the surge energy is charged and stored in the capacitor C through the resistors R and D in the RDC damping circuit. When the surge moves backward and the peak value gradually decreases, the energy stored in the capacitor is released to the bus through the resistors R and D to maintain the stability of the bus voltage, while preparing for the damping absorption and energy storage when the next surge cycle arrives. After the counter-surge passes through the RDC damping circuit, the peak value of the surge wave is significantly attenuated. The introduction of the transient suppression diode limits the maximum positive amplitude of the transient voltage of the surge wave to the range of (transient suppression diode reverse breakdown threshold voltage + bus power supply voltage).

[0022] After attenuation by the damping absorption circuit, the voltage peak-to-peak value Vpp of the surge wave drops from a higher value (for example, 300V) before entering the filter to a lower value (for example, 220V). Then the surge wave continues to enter the high-frequency power supply filter circuit module composed of the fourth-order Butterworth low-pass filter circuit. The fourth-order Butterworth low-pass filter circuit has a strong blocking and attenuation effect on surge interference waves with a frequency higher than the cutoff frequency of the filter circuit. Therefore, after the high-frequency surge wave passes through the circuit module, the original surge wave continues to be attenuated by dozens of times. Moreover, the higher the frequency, the greater the attenuation amplitude. For example, the surge wave Vpp attenuates from the original 220V to 22V.

[0023] After the surge wave is attenuated by the high-frequency power filter circuit module, it continues to move forward and enters the π-type low-frequency power filter circuit module with a fully balanced circuit structure. Since the values ​​of the series inductor and parallel capacitor in the low-frequency power filter circuit module are much larger than the corresponding components in the previous high-frequency power filter circuit module, the surge wave is blocked and attenuated more than the upper circuit, for example, the surge wave Vpp is attenuated from 22V to 1.1V.

[0024] When the Vpp of the original surge wave drops from an extremely high value, for example 300V, to a lower value, for example 1.1V, after passing through the filter of the present invention, the Vpp value of the interference wave is already much lower than the ripple voltage value on the normal DC power bus, and the interference wave can no longer interfere with or damage the on-board electronic control equipment that is also connected to the DC bus.

[0025] Since the high and low frequency filter circuit modules of the DC system anti-counterattack interference power supply filter described in the present invention adopt a fully symmetrical structure, the surge wave that generates counterattack interference has the same blocking effect on the counterattack surge wave regardless of whether it enters from the positive end of the power bus or the negative end of the power bus. At the same time, considering that the object involved in the present invention is the interference of the DC bus, the selection of the transient suppression diode adopts the selection of the unidirectional diode structure. If the object involved is the AC bus, the selection of the transient suppression diode must adopt the selection of the bidirectional diode structure.

[0026] Since the DC system anti-counter-interference power supply filter described in the present invention adopts a combination of three modules, especially the introduction of the RDC damping circuit and the combination design of high and low frequency filters using spectrum separation processing for the full frequency band of counter-interference, the filtering efficiency of the filter described in the present invention is much higher than that of general filters, and the filtering efficiency is dozens of times that of traditional filters. In addition, the inductor design in the present invention is also different from the design of the inductor in the traditional filter. It adopts a large air gap design of a double E-shaped structure with an extended column height, which greatly improves the reliability and safety of the inductor in the DC environment, so that the DC system anti-counter-interference power supply filter described in the present invention can effectively avoid the continuous high-amplitude surge impact associated with the operation of the locomotive air conditioner, which may bring security threats to the locomotive electronic equipment, and bring substantial progress to the safety and punctuality of locomotive operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Attached Figure 1 This is a principle block diagram of a DC system anti-back-interference power supply filter provided in an embodiment of the present invention.

[0028] Attached Figure 2 This is a schematic diagram of a DC system anti-counter-interference power supply filter circuit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1As shown, the DC system anti-counterattack interference power supply filter of the present invention includes: a group of π-type low-frequency power supply filter circuit modules with a fully balanced circuit structure mainly for suppressing low-frequency component electromagnetic interference, a group of high-frequency power supply filter circuits composed of a fourth-order Butterworth low-pass filter circuit with a fully balanced circuit structure mainly for suppressing medium and high frequency component electromagnetic interference, and a group of RDC damping absorption circuit modules mainly for absorbing high-amplitude DC current surges; the low-frequency power supply filter circuit module and the high-frequency power supply filter circuit module are connected in series and then connected in parallel with the RDC damping absorption circuit module.

[0031] The π-type low-frequency power supply filter circuit module of the fully balanced circuit structure is composed of iron core inductors L1, C1, C2, C3, and C4. C1 and C2 constitute a rear-stage low-frequency filter capacitor group, and C3 and C4 constitute a front-stage low-frequency filter capacitor group. L1 is a low-frequency inductor of the fully balanced circuit structure. The π-type low-frequency power supply filter circuit module of the entire fully balanced circuit structure is composed of two groups of front and rear capacitor filter circuits and a low-frequency inductor of the fully balanced circuit structure. Each group of capacitor filter circuits is respectively formed by an electrolytic capacitor and a non-polar high-frequency capacitor in parallel. C1 and C3 are electrolytic capacitors, and C2 and C4 are non-polar high-frequency capacitors. The low-frequency inductor L1 is composed of two groups of completely identical coils, which are respectively connected in series with the positive and negative power bus main circuits. The two groups of capacitor filter circuits are respectively connected in parallel between the two ends of the external leads of the low-frequency inductor of the fully balanced circuit structure. In this embodiment, the capacitance of the electrolytic capacitor C1 facing the DC power bus is 1500μF, and the withstand voltage is 250V. The capacitance of the non-polar high-frequency capacitor C2 is 4.7μF, and the withstand voltage is 2kV. The low-frequency inductor of the fully balanced circuit structure in this embodiment is a differential mode suppression inductor, the same-name end of the coil is consistent with the current inflow direction, and the independent inductance of the two sets of coils is 1mH. In this embodiment, the capacitance of the electrolytic capacitor C3 facing the load device side is 1200μF, and the withstand voltage is 250V. The capacitance of the non-polar high-frequency capacitor C4 is 4.7μF, and the withstand voltage is 2kV. The withstand voltage design of the above electrolytic capacitor is determined by the DC power bus voltage being a reference value of 110V with a 100% redundancy value.

[0032] In this embodiment, the second-order Butterworth low-pass filter circuits of the two-stage mutually related fully balanced circuit structure are connected in series to form a fourth-order Butterworth low-pass filter circuit of a fully balanced circuit structure. The fourth-order Butterworth low-pass filter circuit of the fully balanced circuit structure is composed of C5, L2 (L21, L22) L3, L4, and C6.

[0033] In this embodiment, the first-stage second-order Butterworth low-pass filter circuit is composed of a main high-frequency inductor L2 (L21, L22) with a fully balanced circuit structure and a non-polar high-frequency capacitor C5. The main high-frequency inductor is composed of two groups of completely identical coils. The two groups of coils of the main high-frequency inductor are respectively connected in series with the positive and negative power busbars, and the main high-frequency filter capacitor is connected in parallel between the outer leads of the two groups of coils; the main high-frequency inductor with a fully balanced circuit structure in this embodiment is a differential mode suppression inductor, the same-name ends of the coils are consistent with the current inflow direction, and the independent inductance of the two groups of coils is 20μH. The capacitance of the main high-frequency filter capacitor in this embodiment is 4.7μF, and the withstand voltage value is 2kV.

[0034] In the present embodiment, the inductor of the second-stage second-order Butterworth low-pass filter circuit is composed of two independent auxiliary inductors L3 and L4 with the same parameters and a non-polar auxiliary high-frequency capacitor C6. The two independent auxiliary inductors with the same parameters are respectively connected in series with the positive and negative power bus bars, and the non-polar auxiliary high-frequency capacitor is connected in parallel to the outer ends of the two auxiliary inductors. In the present embodiment, the inductance of the two auxiliary high-frequency inductors of the fully balanced circuit structure is 20μH, the capacitance of the non-polar auxiliary high-frequency filter capacitor is 2.2μF, and the withstand voltage value is 2kV.

[0035] The present embodiment comprises a group of RDC damping absorption circuit modules R1, R2, DV1, DV2, C7, and C8 with redundant design mainly for suppressing high-amplitude DC current surge, wherein R1, DV1, and C7 constitute a first group of RDC damping absorption circuits, and R2, DV2, and C8 constitute a second group of RDC damping absorption circuits. The two groups of RDC damping absorption circuits are connected in parallel to form a dual-group redundant circuit structure mode, which are mutually redundant. When no device fails, they can be regarded as two RDC damping absorption circuits connected in parallel. The parallel connection of the two RDC units can further reduce the electrical stress of the RDC circuit to withstand surges, making the RDC circuit safer; each group of the RDC circuits is connected in parallel by a high-power resistor and an anti-surge unidirectional transient suppression diode, and the cathode of the transient suppression diode faces the positive side of the power bus, and the anode of the transient suppression diode faces the negative side of the power bus; the parallel circuit is then connected in series with a capacitor to form an RDC damping absorption circuit. Any one of the RDC damping absorption circuit modules can bear the energy absorption of suppressing high-amplitude DC current surges in a single-group working mode, and the two-group redundant design can make the RDC damping absorption safer and more reliable. In this embodiment, the design value of the resistor R is 5.1kΩ and the power value is 20W; the reverse breakdown voltage value of the transient suppression diode is 110V, and the maximum reverse breakdown current is 10A; the capacitance of the capacitor is 0.47μF.

[0036] The low-frequency inductor in the filter circuit module described in this embodiment adopts E42 cold-rolled high-frequency silicon steel sheet and coil to form a double E-shaped inductor, and the magnetic gap at the end face of the double E-shaped iron core is 10mm; the inductor includes two groups of completely identical coils, and the same-name ends of the coils are the respective current inflow directions. The actual function of the inductor is equivalent to the series connection of two groups of coils; the enlarged magnetic gap can effectively prevent magnetic saturation in a DC environment, ensuring the safety and stability of the inductor.

[0037] In this embodiment, the high-frequency main inductor and the high-frequency auxiliary inductor are both composed of a double E-shaped magnetic core and a coil. In this embodiment, the high-frequency main inductor magnetic core is model EE130G, two pairs of magnetic cores are used together, and the end magnetic gap is 12mm. The high-frequency main inductor includes two groups of completely identical coils, and the same-name ends of the coils are the respective current inflow directions. The actual function of the inductor is equivalent to the series connection of the two groups of coils; the high-frequency auxiliary inductor magnetic core model is EE120, two pairs are used together, and the end magnetic gap is 10mm; the enlarged magnetic gap can effectively prevent magnetic saturation in a DC environment, ensuring the safety and stability of the inductor.

[0038] The π-type low-frequency power supply filter circuit module of the fully balanced circuit structure and the high-frequency power supply filter circuit module of the fourth-order Butterworth low-pass filter circuit of the fully balanced circuit structure described in the present invention process the entire spectrum of the interference wave through appropriate frequency division between the two groups of modules. In this embodiment, the frequency division point is set to 12kHz, and the surge interference wave higher than 12kHz is effectively suppressed by the high-frequency power supply filter circuit module of the fourth-order Butterworth low-pass filter circuit of the fully balanced circuit structure mainly for suppressing the electromagnetic interference of medium and high frequency components. The surge interference wave lower than 12kHz is suppressed by the π-type low-frequency power supply filter circuit module of the fully balanced circuit structure mainly for suppressing the electromagnetic interference of low-frequency components after the interference wave passes through the high-frequency power supply filter circuit module. This low-frequency power supply filter circuit only needs to bear the filtering effect of the counter-attack interference wave of the lower frequency below 12kHz, but it also has a strong filtering function for the counter-attack interference wave of the higher frequency above 12kHz. At the same time, the functions of the two filters are complementary, and the filtering effect is better.

[0039] In this embodiment, the low-frequency inductor in the π-type low-frequency power supply filter circuit module of the fully balanced circuit structure mainly for suppressing low-frequency electromagnetic interference adopts an E-shaped cold-rolled high-frequency silicon steel sheet core. By using the silicon steel sheet core inductor, an inductance several times larger than that of a ferrite core inductor can be obtained under the same conditions, and the anti-EMI capability is correspondingly several times stronger than that of a ferrite core inductor, and the failure rate is extremely low. In this embodiment, the low-frequency operating frequency is set to 12kHz. When the operating point frequency of the inductor of the E-shaped silicon steel sheet core is lower than 12kHz, the heating problem of the silicon steel sheet core is also well solved, and the blocking effect on low-frequency interference waves is more effective.

[0040] In this embodiment, the high-frequency inductor in the high-frequency power supply filter circuit module of the fourth-order Butterworth low-pass filter circuit with a fully balanced circuit structure that mainly suppresses electromagnetic interference of medium and high frequency components adopts a special zinc-manganese ferrite magnetic material E-shaped core. The zinc-manganese ferrite core inductor has good high-frequency responsiveness and is more effective in suppressing medium and high frequency interference above 12kHz.

[0041] The DC system anti-counter-interference power supply filter described in this embodiment achieves filtering of counter-interference waves in this way.

[0042] When the locomotive air-conditioning inverter is running, the DC current surge generated by the counter-interference to the bus enters the filter. The counter-interference of the surge interference wave is loaded on the two ends of the RDC damping absorption circuit of the filter. The RDC circuit bears the brunt of the impact of the counter-surge. During the surge impact, the RDC absorption circuit absorbs the surge energy through the RDC circuit. If the transient positive voltage of the surge wave is higher than the bus voltage amplitude and lower than (transient suppression diode reverse breakdown threshold voltage + bus power supply voltage) for example 180V, the surge energy is gradually charged and stored in the capacitor C through the resistor R in the RDC damping circuit. At the same time, the surge peak voltage is weakened as the resistor R absorbs the damping; if the transient positive voltage of the surge wave is higher than (transient suppression diode reverse breakdown threshold voltage + bus power supply voltage) for example 180V, the surge energy is gradually charged and stored in the capacitor C through the resistor R in the RDC damping circuit. At the same time, the surge peak voltage is weakened as the resistor R absorbs the damping; if the transient positive voltage of the surge wave is higher than (transient suppression diode reverse breakdown threshold voltage + bus power supply voltage) for example 180V, the surge energy is gradually charged and stored in the capacitor C through the resistor R in the RDC damping circuit. Threshold voltage + bus power supply voltage) is 250V. The surge energy charges and stores capacitor C through resistors R and D in the RDC damping circuit. Due to the existence of transient suppression diodes, the maximum peak voltage of the surge is limited to about +220V. When the surge moves backward, the peak value gradually decreases, and the energy stored in the capacitor is released to the bus through resistors R and D, and partially maintains the stability of the bus voltage. At the same time, it prepares for damping absorption and energy storage when the next surge cycle arrives. After the counter-surge passes through the RDC damping circuit, the peak value of the surge wave is significantly attenuated. The introduction of transient suppression diodes limits the maximum positive amplitude of the transient voltage of the surge wave to the range of (transient suppression diode reverse breakdown threshold voltage + bus power supply voltage) 220V.

[0043] After attenuation by the damping absorption circuit, the voltage peak-to-peak value Vpp of the surge wave drops from a maximum value of 250V before entering the filter to a lower value of 220V. If the maximum peak voltage of the surge is less than 220V, it will be lower than 220V after passing through the RDC damping absorption circuit. After being damped and absorbed by the damping absorption circuit module, the surge wave continues to move forward into the high-frequency power supply filter circuit module composed of the fourth-order Butterworth low-pass filter circuit. The fourth-order Butterworth low-pass filter circuit has a very strong blocking and attenuation effect on surge interference waves higher than the cutoff frequency of the filter circuit. For example, for a surge wave with a main frequency of 45kHz, the attenuation of this filter can reach 30db. Therefore, after the high-frequency surge wave passes through the circuit module, the original surge wave continues to be attenuated by dozens of times, and the higher the frequency, the greater the attenuation amplitude. For example, the surge wave Vpp is attenuated from the original 220V to 22V, and the interference wave of the high-order harmonic component basically disappears.

[0044] After being attenuated by the high-frequency power filter circuit module, the surge wave continues forward and enters the π-type low-frequency power filter circuit module with a fully balanced circuit structure. Since the values ​​of the series inductor and parallel capacitor in the low-frequency power filter circuit module are much larger than the corresponding components in the previous high-frequency power filter circuit module, the blocking and attenuation of the high-order harmonics of the surge wave are greater than those of the upper circuit, for example 30db. For low-frequency interference waves below 12kHz, the surge wave Vpp is attenuated from 22V to 1.1V under the filtering of the π-type low-frequency power filter circuit with a fully balanced circuit structure.

[0045] When the Vpp of the original surge wave drops from an extremely high value, for example 250V, to a lower value, for example 1.1V, after passing through the filter of the present invention, the Vpp value of the interference wave is already much lower than the ripple voltage value on the normal DC power bus, and its amplitude is already much smaller than the maximum allowable voltage fluctuation of the on-board driving equipment, which means that the voltage amplitude of the counter-interference surge wave entering the on-board electronic equipment has entered the safe zone and can no longer interfere with and damage the on-board electronic control equipment also connected to the DC bus.

[0046] The high and low frequency filter circuit modules of the DC system anti-counterattack interference power supply filter in this embodiment adopt a fully symmetrical structure, so whether the surge wave generating counterattack interference enters from the positive end of the power bus or from the negative end of the power bus, the filter has the same blocking effect on the counterattack surge wave and has a huge capacity. At the same time, considering that the object involved in the present invention is the interference of the DC bus, the selection of the transient suppression diode adopts the selection of the unidirectional diode structure. If the object involved is the AC bus, the selection of the transient suppression diode must adopt the selection of the bidirectional diode structure.

[0047] In this embodiment, the main frequency of the counter-interference is 45kHz, and the high-order harmonic components in the interference are complex, but the main harmonic energy is concentrated in the medium and low frequency range. The frequency band separation filtering (i.e., graded filtering) technical solution is adopted for the full frequency band of the counter-interference. The low-frequency filter composed of the iron core inductor is used to process the medium and low frequency harmonics, and the medium and high frequency filter composed of the magnetic core inductor is used to process the medium and high frequency harmonics, so that the filter circuit can obtain an enhanced filtering effect in the whole frequency domain, and the filter frequency suppression curve is smoothly connected from low frequency to high frequency; and then the RDC damping absorption circuit is integrated. The introduction of the RDC damping absorption circuit is directly effective for the damping and attenuation of the DC surge, which not only increases the filtering effect of the filter, but also maximizes the protection of the safety and reliability of the filter circuit module.

[0048] The frequency division point in the frequency band separation filter described in this embodiment is designed to be 12 kHz, which is a result of balancing the frequency response characteristics of the iron core inductor and the frequency response characteristics of the magnetic core inductor.

[0049] The design of the DC system anti-back-interference power supply filter inductor described in the present invention not only adds a large magnetic gap design, but also adopts a dual magnetic core parallel design, which increases the cross-sectional area of ​​the magnetic core, so that the inductor in the filter is magnetically unsaturated under the DC maximum current load and the maximum surge impact, so that the full life cycle of the magnetic core inductor is extended by more than dozens of times, effectively improving the reliability and safety of the inductor in the DC environment, making the DC system anti-back-interference power supply filter described in the present invention more suitable for operation in a locomotive environment, effectively avoiding the continuous high-amplitude surge impact associated with the operation of the locomotive air conditioner. The possible safety threat to the locomotive electronic equipment brings substantial progress to the safety and punctuality of locomotive operation.

[0050] The redundant technology design is adopted in this design, which is not only reflected in the module design of the RDC absorption circuit, but also in the design of high and low frequency inductors. In the design of all inductors in this embodiment, while increasing the magnetic gap, the cross-sectional area of ​​each magnetic core of the iron core is also doubled to ensure the magnetic unsaturation of the inductor; the redundant technology design is also reflected in the selection of component parameters of the high-frequency filter. The withstand voltage value of all non-polar high-frequency capacitors in the fourth-order Butterworth filter in this embodiment is 2kV, which has taken into account the electromagnetic resonance that may occur in the filter itself during high-frequency filtering; the withstand voltage value of the electrolytic capacitor in the low-frequency filter is 250V, which is also selected after redundancy. The redundancy index value in this embodiment far exceeds the relevant technical standards. Such technical references can ensure the reliability and safety of the filter in actual application of locomotives.

Claims

1. A DC system anti-rebound interference power supply filter, characterized in that The invention comprises: a group of π-type low-frequency power supply filter circuit modules with a fully balanced circuit structure mainly for suppressing electromagnetic interference of low-frequency components, a group of high-frequency power supply filter circuit modules with a fully balanced circuit structure of a fourth-order Butterworth low-pass filter circuit mainly for suppressing electromagnetic interference of medium- and high-frequency components, and a group of RDC damping absorption circuit modules with a redundant design mainly for suppressing high-amplitude DC current surges; the low-frequency power supply filter circuit modules and the high-frequency power supply filter circuit modules are connected in series and then connected in parallel with the RDC damping absorption circuit module; the π-type low-frequency power supply filter circuit module with a fully balanced circuit structure is composed of two groups of capacitor filter circuits and a low-frequency inductor with a fully balanced circuit structure, and each group of capacitor filter circuits is respectively composed of an electrolytic capacitor and a non-polar high-frequency capacitor connected in parallel; The inductor of the fully balanced circuit structure is composed of two groups of completely identical coils, which are respectively connected in series with the positive and negative bus main circuits, and the two groups of capacitor filter circuits are respectively connected in parallel between the two ends of the outer leads of the low-frequency inductor of the fully balanced circuit structure; the high-frequency power supply filter circuit module is composed of a fourth-order Butterworth low-pass filter circuit of the fully balanced circuit structure, wherein the fourth-order Butterworth low-pass filter circuit is composed of two levels of mutually related second-order Butterworth low-pass filter circuits, and each level of the second-order Butterworth low-pass filter circuit adopts a fully balanced circuit structure, wherein the first-stage filter circuit is composed of a main high-frequency inductor composed of two groups of coils and a non-polar high-frequency capacitor, and the filter capacitor is connected in parallel between the outer leads of the two groups of coils; wherein the inductor of the second-stage filter is composed of two independent high-frequency auxiliary inductors with the same parameters and a The invention is composed of a non-polar high-frequency capacitor, and the filter capacitor is connected in parallel to the two ends of the two inductors; the two-stage associated filters are connected in series to form a fourth-order Butterworth low-pass filter circuit; the group of RDC damping absorption circuit modules with redundant design mainly for suppressing high-amplitude DC current surges is connected in parallel by a high-power resistor and an anti-surge unidirectional transient suppression diode, and the cathode of the transient suppression diode faces the positive side of the power bus, and the anode of the transient suppression diode faces the negative side of the power bus; the parallel circuit is then connected in series with the capacitor to form an RDC damping absorption circuit and is connected in parallel in a dual circuit structure redundancy mode; the high-frequency main and auxiliary inductors in the filter circuit module are composed of a double E-shaped magnetic core and a coil; the low-frequency inductor is composed of a double E-shaped iron core and a coil, and the double E-shaped combined end face is designed with an air gap.

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