Three-phase static change-over switch and change-over control method

Abstract

The invention relates to a three-phase static change-over switch comprising an input module which is provided with two paths of alternating current power supplies, one path of alternating current power supply is a main power supply, and the other path of alternating current power supply is a standby power supply; the output module is connected with a load and used for outputting one path of alternating-current power to the load; the control module comprises an FPGA control unit, a driving circuit unit and a protection circuit unit, the FPGA control unit is electrically connected with the driving circuit unit and the protection circuit unit, the driving circuit unit comprises an optical fiber isolator and IGBT static switches, the input end of the optical fiber isolator is connected with the FPGA control unit, the output end of the optical fiber isolator is connected with a pair of IGBT static switches, and the IGBT static switches are electrically connected with the FPGA control unit. The pair of IGBT static switches are reversely connected in parallel, two paths of alternating-current power supplies are connected to the pair of IGBT static switches respectively, the FPGA control unit is used for controlling the pair of IGBT static switches to output one path of alternating-current power supply to the output module, and the pair of IGBT static switches are reversely connected in parallel, so that bidirectional conduction capability is formed, the full cycle of the alternating-current power supplies can be covered, and efficient switching can be realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power electronics, and particularly relates to a three-phase static switching switch and a switching control method. BACKGROUND

[0002] The three-phase static switching switch (STS) is a kind of non-contact electronic device for fast switching between two independent AC power sources. The three-phase static switching switch (STS) realizes fast switching between two power sources through high-speed thyristors and intelligent control boards, and ensures that the power supply interruption of the load does not exceed one power frequency cycle. The existing three-phase static switching switch mainly has the following problems:

[0003] (1) High-frequency interference problem: the traditional scheme does not specifically suppress the high-frequency interference of 1500kHz-30MHz frequency band, resulting in electromagnetic leakage exceeding the limit value (such as 30MHz frequency band conducted disturbance exceeding the limit value of CISPR22 standard);

[0004] (2) Conduction leakage risk: there is a lack of high-performance filtering design between the power supply and the device, which is easy to leak sensitive signals (such as keyboard input information being detected by ground wire) through ground wire or neutral line;

[0005] (3) Insufficient switching performance: mechanical switching switch has millisecond-level delay and arc interference, which cannot meet the uninterrupted power supply demand of precision load. SUMMARY

[0006] In order to solve the above technical problems, the purpose of the present application is to provide a three-phase static switching switch and a switching control method, which can solve the problem of high-frequency interference suppression.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0008] A three-phase static switching switch, comprising:

[0009] An input module having two AC power sources; one of the AC power sources is a main power source, and the other AC power source is a backup power source;

[0010] An output module connected to a load and used for outputting one AC power source to the load;

[0011] A control module, the control module comprises an FPGA control unit, a driving circuit unit and a protection circuit unit, the FPGA control unit is electrically connected with the driving circuit unit and the protection circuit unit, the driving circuit unit comprises a fiber optic isolator and an IGBT static switch, an input end of the fiber optic isolator is connected with the FPGA control unit, an output end of the fiber optic isolator is connected with a pair of IGBT static switches, the pair of IGBT static switches are connected in reverse parallel, two-way AC power supplies are respectively connected with the pair of IGBT static switches, and the FPGA control unit is used for controlling the pair of IGBT static switches to output one-way AC power supply to an output module.

[0012] Further, the output module comprises an output selection switch, a three-stage filter unit and a conduction leakage protection unit which are sequentially connected in series, the three-stage filter unit is connected with a load and the conduction leakage protection unit, the load is connected with the conduction leakage protection unit, the output selection switch is connected with the pair of IGBT static switches, the three-stage filter unit comprises a first-stage filter assembly, a second-stage filter assembly and a third-stage filter assembly, the first-stage filter assembly comprises a common-mode choke and an X capacitor, the common-mode choke is connected in series on L line and N line, and the X capacitor is connected in parallel between L line and N line, the second-stage filter assembly comprises a feed-through filter and a Y capacitor, the feed-through filter is connected in series on L line and N line and connected with the common-mode choke, and the Y capacitor is connected between L line and PE line and N line and PE line, and the third-stage filter assembly comprises a nanocrystalline magnetic ring and a three-terminal capacitor, the nanocrystalline magnetic ring is connected in series on L line and N line at an output end of the feed-through filter, and an input end of the three-terminal capacitor is connected with the Y capacitor through L line and N line, and an output end is connected with the load and the conduction leakage protection unit.

[0013] Further, the conduction leakage protection circuit comprises an isolation transformer, a Y capacitor group and a double-layer shielding cable, a primary winding of the isolation transformer is connected with an output end of the three-terminal capacitor, a shielding layer of the isolation transformer is grounded, a secondary winding of the isolation transformer is connected in parallel with the Y capacitor group and then grounded, and the secondary winding is also connected with the load through the double-layer shielding cable.

[0014] Further, the double-layer shielding cable comprises an inner shielding layer, an outer shielding layer and an internal wire, the inner shielding layer is a copper mesh braid layer covering the outside of the internal wire, the outer shielding layer is formed by a plurality of ferrite magnetic rings sleeving the outer periphery of the inner shielding layer, and the internal wire is a twisted pair wire.

[0015] Further, the input module further comprises an EMC filter, the EMC filter is connected in series with the AC power supply and then connected with the pair of IGBT static switches.

[0016] Further, the FPGA control unit comprises a CPU, a DESAT protection control module, a PWM generation module, a switching decision FSM module and a zero-crossing comparison synchronization detection module, the CPU is electrically connected to the DESAT protection control module, the PWM generation module, the switching decision FSM module and the zero-crossing comparison synchronization detection module respectively, the zero-crossing comparison synchronization detection module is used for receiving sensor signals of the input module and outputting to the switching decision FSM module, and is used for providing a zero-crossing signal to the PWM generation module, the PWM generation module generates a driving signal to the optical fiber isolation according to the decision of the switching decision FSM module to control the on-off of a pair of the IGBT static switches, and the DESAT protection control module is used for receiving a protection signal of the protection circuit unit and transmitting the protection signal to the switching decision FSM module.

[0017] Further, the protection circuit unit comprises a hardware comparator and a DESAT detection protection module, the DESAT detection protection module and the hardware comparator are used for sending a protection signal to the DESAT protection control module when overcurrent, overvoltage or overtemperature occurs.

[0018] Further, the zero-crossing comparison synchronization detection module comprises a zero-crossing comparator and a synchronization detector, the zero-crossing comparator is used for detecting sensor signals of an alternating power supply, and when the sensor signals cross zero, the synchronization detector is triggered to calculate the phase difference of a pair of alternating power supplies, and the switching decision FSM module generates a driving signal according to the phase difference.

[0019] The application also provides a three-phase static switching switch switching control method, which applies the three-phase static switching switch, and the control method comprises the following steps:

[0020] Step S1: detecting whether the main power supply is normal, if normal, supplying power through the main power supply;

[0021] Step S2: if the main power supply is abnormal, blocking the driving signal of the IGBT static switch of the main power supply within a predetermined time;

[0022] Step S3: delaying a certain time to confirm whether the main power supply fault is continuous, if continuous, executing the next step;

[0023] Step S4: detecting whether the standby power supply is normal, if normal, continuing to the next step;

[0024] Step S5: turning on the IGBT static switch of the standby power supply at the voltage zero-crossing point of the standby power supply;

[0025] Step S6: turning off the IGBT static switch of the main power supply.

[0026] Further, the voltage zero-crossing point is the intersection of the voltage waveform of the main power supply and the voltage waveform of the backup power supply.

[0027] The present application has the following advantages and effects due to the above technical solutions:

[0028] 1. The three-phase static switching switch and switching control method of the present application, by a pair of IGBT static switching reverse parallel, form bidirectional conduction ability, can cover the whole cycle of alternating current power supply, without additional diode, and can realize high efficient switching, meet the redundancy demand of high reliability system, reduce the FPGA resource occupation.

[0029] 2. The three-phase static switching switch and switching control method of the present application, adopts three-stage filtering to cover 10kHz-100MHz full-band interference suppression, solves the problem of insufficient high-frequency interference suppression of STS1500kHz-30MHz frequency band, avoids electromagnetic leakage exceeding standard (such as 30MHz conducted disturbance conforms to CISPR22 standard), and significantly improves the high-frequency interference suppression ability.

[0030] 3. The three-phase static switching switch and switching control method of the present application, by isolation transformer, Y capacitor group and double-layer shielding cable, constructs multiple protection to form a conducted leakage protection circuit, the isolation transformer blocks the ground loop noise, the shielding layer single-point ground cuts off the high-frequency coupling path, and the double-layer shielding cable can absorb high-frequency energy and suppress cable radiation leakage, effectively preventing sensitive signals from leaking through the ground or neutral line, and further improving the anti-interference ability.

[0031] 4. The three-phase static switching switch and switching control method of the present application, based on the zero-current switching algorithm of FPGA, triggers IGBT conduction at the voltage zero-crossing point of the backup power supply, avoids voltage fluctuation and electromagnetic interference caused by current mutation, significantly improves the continuity of current waveform, and accurately calculates the phase difference between main / backup power supply through Cordic algorithm (resolution 0.1°), ensures the switching timing accuracy, and further reduces the switching impact. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is the architecture block diagram of the three-phase static switching switch of the present application.

[0033] Figure 2 It is the circuit diagram of three-stage filtering unit.

[0034] Figure 3 It is the schematic diagram of isolation transformer.

[0035] Figure 4 It is the schematic diagram of the grounding system of the conducted leakage protection unit.

[0036] Figure 5 It is the schematic diagram of the shielding cable of the conducted leakage protection unit.

[0037] Figure 6 Connection diagram for single-phase IGBT static switch.

[0038] Figure 7 Control diagram for protection circuit unit.

[0039] Figure 8 Architecture diagram for FPGA control unit.

[0040] Figure 9 Flow chart for phase synchronization detection algorithm.

[0041] Figure 10 State flow chart for switching method of the present application.

[0042] Figure 11 Waveform diagram for switching voltage zero-crossing point of the present application.

[0043] Figure 12 Waveform diagram for switching current of the present application.

[0044] Figure 13 Signal diagram for switching of the present application.

[0045] The reference signs are as follows: 1-input module, 2-control module, 201-protection circuit unit, 202-FPGA control unit, 203-driving circuit unit, 3-output module, 4-radiating module, 5-load, 101-alternating current power supply, 102-fuse, 103-EMC filter, 2031-optical fiber isolation, 2032-IGBT static switch, 2033-driving circuit, 301-output selection switch, 302-three-stage filter unit, 303-conduction leakage protection unit, 3021-three-phase input end, 3022-first-stage filter assembly, 3023-second-stage filter assembly, 3024-third-stage filter assembly, 3025-three-phase output end, 30221-common-mode choke, 30222-X capacitor, 30231-feedthrough filter, 30232-Y capacitor, 30241-nanocrystalline magnetic ring, 30242-three-terminal capacitor, 3031-isolation transformer, 3032-Y capacitor group, 3033-double-layer shielded cable, 30311-primary winding, 30312-secondary winding, 30313-shielding layer, 303121-secondary hot line output end, 303122-secondary zero line output end, 303123-secondary PE end, 30314-first single-point grounding system, 30315-second single-point grounding system, 30331-inner shielding layer, 30332-ferrite magnetic ring, 30333-internal wire L line, 30334-internal wire N line, 30335-equipotential grounding ring, 2011-overcurrent fault detection channel, 2012-overvoltage fault detection channel, 2013-overtemperature fault detection channel, 2014-hardware comparator, 2015-DESAT detection protection module, 2016-thermistor, 401-radiator, 402-fan. DETAILED DESCRIPTION

[0046] The embodiments of the present application will be described in detail below with reference to the accompanying drawings, so that the purpose, characteristics and advantages of the present application can be more clearly understood. It should be understood that the embodiments shown in the drawings are not a limitation on the scope of the present application, but are only used to illustrate the essential spirit of the technical scheme of the present application.

[0047] As shown in the accompanying drawings. Figure 1 The present application provides a three-phase static switching switch, which comprises an input module 1, a control module 2, an output module 3 and a radiating module 4. The input module 1 comprises two-way alternating current power supply 101, and the two-way alternating current power supply 101 is output to the control module 2. The control module 2 is electrically connected with the input module 1 and the output module 3 and is used for controlling the two-way alternating current power supply 101 of the input module 1, and according to the state of the two-way alternating current power supply 101, one-way alternating current power supply is selected and output to the load 5 by the output module 3.

[0048] The input module 1 further comprises a fuse 102 and an EMC filter 103, wherein the AC power supply 101 is a 380V / 100A three-phase AC power supply, one of which is the main power supply and the other is the standby power supply. The three-phase live wire end of each AC power supply 101 is respectively a live wire end L1, a live wire end L2 and a live wire end L3, which are connected in series after the fuse 102 and then connected to the EMC filter 103, the neutral wire end N is directly connected to the EMC filter 103, and the ground wire end PE is connected to the ground end GND. The EMC filter 103 is used to suppress the interference of the AC power supply 101, and one end of the EMC filter 103 is connected to the control module 2, and the control module 2 outputs voltage or current sensor signals.

[0049] The output module 3 comprises an output selection switch 301, a three-stage filter unit 302 and a conduction leakage protection unit 303, the output selection switch 301 is electrically connected to the three-stage filter unit 302, the load 5 and the conduction leakage protection unit 303 are connected to the three-stage filter unit 302, the load 5 is connected to the conduction leakage protection unit 303, and one end of the output selection switch 301 is connected to the control module 2.

[0050] As shown in Figure 2 The three-stage filter unit 302 is composed of a three-phase input end 3021, a first-stage filter assembly 3022, a second-stage filter assembly 3023, a third-stage filter assembly 3024 and a three-phase output end 3025 connected in series, the three-phase input end 3021 includes a live wire end Lin, a neutral wire end Nin and a ground wire end PEin, the live wire end Lin is composed of Lin1, Lin2 and Lin3, and the three-phase input end 3021 is connected to the three-phase end of the output selection switch 301 in correspondence. The three-phase output end 3025 includes a live wire end Lout, a neutral wire end Nout and a ground wire end PEout, and the live wire end Lout is composed of Lout1, Lout2 and Lout3. The three-phase output end 3025 is connected to the conduction leakage protection unit 303 and the load 5.

[0051] Among them, the first-stage filter assembly 3022 includes a common-mode choke 30221 and an X capacitor 30222, the common-mode choke 30221 is connected to the live wire end Lin and the neutral wire end Nin of the three-phase input end 3021 after being connected in series with the L line and the N line, so as to suppress common-mode noise, and the X capacitor 30222 is connected in parallel between the L line and the N line (not shown in the figure) to filter out differential-mode interference. The X capacitor 30222 is 0.47μF.

[0052] The secondary filter assembly 3023 includes a feed-through filter 30231 and a Y-capacitor 30232, the feed-through filter 30231 is connected in series with the L line and the N line (not shown in the L line and the N line diagram) to the common-mode choke 30221, and the Y-capacitor 30232 is connected between the L-PE (the L line and the PE line, not shown in the L line and the PE line diagram) and the N-PE (the N line and the PE line, not shown in the N line and the PE line diagram). The Y-capacitor 30232 is used to provide a low-impedance path for common-mode noise to the ground. The Y-capacitor is 5100 pF.

[0053] The tertiary filter assembly 3024 includes a nanocrystalline magnetic ring 30241 and a three-terminal capacitor 30242, the nanocrystalline magnetic ring 30241 is connected to the L line and the N line at the output end of the feed-through filter 30231, and the input end of the three-terminal capacitor 30242 is connected to the Y-capacitor 30232 through the L line and the N line. The output end of the three-terminal capacitor 30242 is connected to the fire line end Lout, the zero line end Nout and the ground line end PEout of the three-phase output end 3025 respectively, wherein the fire line end Lout of the three-phase output end 3025 is connected to the L line of the load 5 (not shown in the L line diagram), the zero line end Nout of the three-phase output end 3025 is connected to the N line of the load 5 (not shown in the N line diagram), and the ground line end PEout of the three-phase output end 3025 is connected to the ground line of the load 5 through the conducted leakage protection unit 303.

[0054] In the present application, the effective frequency band of the primary filter assembly 3022 is 10K-500KHZ, the insertion loss is 35dB@100kHz, and the differential mode interference noise is mainly suppressed. The effective frequency band of the secondary filter assembly 3023 is 500k-10MHz, the insertion loss is 40dB@100kHz, and the common-mode interference noise is mainly suppressed. The effective frequency band of the tertiary filter assembly 3024 is 10M-100MHz, the insertion loss is 50dB@100kHz, and the high-frequency noise is mainly suppressed, thereby forming a full-spectrum interference with an effective frequency band of 10M-100MHz and an insertion loss of 60dB@100kHz by the tertiary filter unit 302.

[0055] As Figures 3-5Further, the conducted leakage protection unit 303 includes an isolation transformer 3031 for blocking the transmission of common-mode noise (especially the noise in the ground loop), a Y capacitor bank 3032, and a double-shielded cable 3033. The isolation transformer 3031 includes a primary winding 30311, a secondary winding 30312, and a shielding layer 30313, the turns ratio of the primary winding 30311 and the secondary winding 30312 being 1:1, so that the voltage remains unchanged. The shielding layer 30313 (usually a copper or aluminum foil) is wrapped between the primary winding 30311 and the secondary winding 30312 and is directly grounded to form a first single-point grounding system 30314 for blocking the interference path coupled through the ground between the primary winding and the secondary winding.

[0056] The ground PEout of the three-phase output end 3025 of the three-stage filter unit 302 is connected to the primary winding 30311 of the isolation transformer 3031, the shielding layer 30313 of the isolation transformer 3031 is grounded, and the secondary winding 30312 of the isolation transformer 3031 is connected to the ground of the load 5 through the double-shielded cable 3033. At the same time, the secondary firewire output end 303121, the secondary zero-line output end 303122, and the secondary PE end 303123 of the secondary winding 30212 are connected in parallel to the Y capacitor bank 3023 and then grounded to form a second single-point grounding system 30315. The second single-point grounding system 30315 effectively cuts off the direct coupling path through the ground between the primary winding and the secondary winding of the isolation transformer 3031, thereby preventing the propagation of high-frequency signals through the ground.

[0057] Further, the double-shielded cable 3033 includes an inner shielding layer 30331, an outer shielding layer, and an internal conductor. The inner shielding layer 30331 is a copper mesh braid layer covering the outside of the internal conductor to provide electrostatic shielding. The outer shielding layer is a plurality of ferrite magnetic rings 30332 arranged around the outer periphery of the inner shielding layer 30331 to form a distributed inductor. The array spacing of the ferrite magnetic rings 30332 is 15-20 mm, and the ferrite magnetic rings 30332 mainly absorb high-frequency energy, thereby suppressing the radiation or conducted leakage of high-frequency signals through the cable. The internal conductor L line 30333 and the internal conductor N line 30334 of the internal conductor are twisted to enhance the suppression ability of differential mode interference. One end of the plurality of ferrite magnetic rings 30332 is connected to the ground through an equipotential grounding ring 30335 to realize grounding.

[0058] Further, the control template 2 comprises an FPGA control unit 202, a drive circuit unit 203 and a protection circuit unit 201, the FPGA control unit 202 is electrically connected with the drive circuit unit 203 and the protection circuit unit 201, the drive circuit unit 203 comprises an optical fiber isolation 2031, an IGBT static switch 2032 and a drive circuit 2033, the input end of the optical fiber isolation 2031 is connected with the FPGA control unit 202, each phase of the output end of the optical fiber isolation 2031 is connected with a pair of IGBT static switches 2032, the pair of IGBT static switches 2032 are reversely connected in parallel, the output selection switch 301 of the output module 3 is connected with the IGBT static switch 2032, the drive circuit 2033 is electrically connected with the optical fiber isolation 2031 and the IGBT static switch 2032 at the same time, and the drive circuit 2033 and the optical fiber isolation 2031 are in bidirectional communication. Two AC power supplies 101 are respectively connected with a pair of IGBT static switches 2032, and the FPGA control unit 202 is used for controlling the pair of IGBT static switches 2032 to output one AC power supply 101 to the output module 3.

[0059] As shown in Figure 6 The two AC power supplies 101 of the input module 1 are respectively connected with a pair of IGBT static switches 2032, the FPGA control unit 202 outputs a PWM signal to the optical fiber isolation 2031, the protection circuit unit 201 simultaneously outputs a protection signal to the drive circuit 2033, the optical fiber isolation 2031 and the drive circuit 2033 are in bidirectional isolation communication, and the drive circuit 2033 simultaneously outputs a control signal to the pair of IGBT static switches 2032 to control the on-off of the AC power supply 101 of the IGBT static switch 2032. The optical fiber isolation 2031 is used for providing electrical isolation output, the drive circuit 2033 is used for controlling the on-off of the IGBT static switch 2032, and the optical fiber isolation 2031 can utilize optical coupling technology to realize optical transmission on a transparent insulation isolation layer (such as an air gap) to achieve the purpose of isolation. The IGBT static switch 2032 adopts a gate driver, the gate driver can serve as an interface between a low-voltage control signal and a high-power semiconductor switch, and can efficiently and reliably drive the IGBT static switch.

[0060] As shown in Figures 7-8The protection circuit unit 201 is used to protect the synchronization and reliability of the IGBT static switch 2032 action of the FPGA control unit 202, and includes a detection layer, a protection layer and an execution layer. The detection layer provides three detection channels, namely an overcurrent fault detection channel 2011, an overvoltage fault detection channel 2012 and an overtemperature fault detection channel 2013. The protection layer is composed of a hardware comparator 2014, a DESAT detection protection module 2015 and a thermistor 2016. The DESAT detection protection module 2015 is used for overcurrent protection, and the response time is less than 10 microseconds, and the action can be immediately performed. The thermistor 2016 is used to detect the temperature signal and then send it to the hardware comparator 2014. The hardware comparator 2014 is used to process overvoltage and overtemperature protection, so as to immediately act when overvoltage and overtemperature occur. The DESAT detection protection module 2015 and the hardware comparator 2014 can send protection signals to the DESAT protection control module 2022 when overcurrent, overvoltage and overtemperature occur, and the FPGA control unit controls the IGBT static switch 2032 to be turned off according to all protection signals.

[0061] When the overcurrent fault detection channel 2011 detects an overcurrent signal, the FPGA control unit 202 controls the IGBT static switch 2032 to be turned off through the DESAT detection protection module 2015. When the overvoltage fault detection channel 2012 and the overtemperature fault detection channel 2013 respectively detect overvoltage signals and overtemperature signals, the hardware comparator 2014 acts to execute the turn-off of the IGBT static switch 2032.

[0062] The protection circuit unit 201 realizes hierarchical fast response. The DESAT detection protection module 2015 is used for fatal faults such as short circuit, and the hardware comparator 2014 can also process power grid abnormalities and overtemperature protection to prevent thermal failure. All protections are finally converged to the FPGA control unit 202 to ensure the synchronization and reliability of the IGBT static switch 2032 action.

[0063] Further, the heat dissipation module 4 includes a heat sink 401 and a fan 402. The heat sink 401 is arranged on the CPU of the FPGA control unit, and the three thermistors 2016 of the protection control unit 201 are respectively installed on the substrate of the IGBT static switch, the heat sink substrate and the case. The airflow direction of the fan 402 is perpendicular to the fins of the heat sink for forced air cooling, and the thermistors 2016 of the protection layer are used to detect the temperature and control the operation of the fan.

[0064] Further, the FPGA control unit 202 comprises a CPU 2021, a DESAT protection control module 2022, a PWM generation module 2023, a switching decision FSM module 2024 and a zero-crossing comparison synchronization detection module 2025, the CPU 2021 is electrically connected to the DESAT protection control module 2022, the PWM generation module 2023, the switching decision FSM module 2024 and the zero-crossing comparison synchronization detection module 2025 respectively, the zero-crossing comparison synchronization detection module 2025 is used to receive the sensor signal of the input module 1 and output to the switching decision FSM module 2024, and is used to provide the zero-crossing signal to the PWM generation module 2023, the PWM generation module 2023 generates the driving signal to the optical isolation 2031 according to the decision of the switching decision FSM module 2024 to control the on-off of the pair of IGBT static switches 2032, the DESAT protection control module 2022 is used to receive the protection signal of the protection circuit unit 201 and transmit the protection signal to the switching decision FSM module 2024.

[0065] Specifically, the zero-crossing comparison synchronization detection module 2025 comprises a zero-crossing comparator 20251 and a synchronization detector 20252, the zero-crossing comparator 20251 is used to receive the sensor signal of the input module, and output the sensor signal to the switching decision FSM module 2024 after detection by the synchronization detector 20252, the zero-crossing comparator 20251 is also used to provide the zero-crossing signal to the PWM generation module 2023, the PWM generation module 2023 generates the driving signal to the optical isolation 2031 of the driving circuit unit 203 according to the decision of the switching decision FSM module 2024, and the DESAT protection control module 2022 is also used to output the protection signal of the protection circuit unit 201 to the optical isolation 2031 of the driving circuit unit 203. When the zero-crossing comparator 20251 detects that the sensor signal (voltage signal) crosses zero (from negative to positive or from positive to negative), the phase calculation of the synchronization detector 20252 is triggered when the sensor signal of the output module 3 passes through the zero-crossing comparator 20251 and the synchronization detector 20252. The synchronization detector 20252 uses the CORDIC algorithm core inside the FPGA control unit 202 to calculate the phase difference of the two AC power supplies 101. At this time, the switching decision FSM module 2024 contains two working states, the first working state is when the main power supply is normal, the first IGBT static switch 2032 is enabled, and the second working state is when the standby power supply is normal, the second IGBT static switch 2032 is enabled.

[0066] As Figure 9The synchronization detector 20252 uses the Cordic algorithm to process the phase information of the two alternating power sources 101, at this time, the sensor signal selects the voltage signal, when the voltage signals of the main power source and the standby power source are sampled by the ADC sampling module and output to the zero-crossing comparator 20251, when the zero-crossing comparator 20251 detects that the voltage signal of any alternating power source crosses zero (from negative to positive or from positive to negative), the Cordic phase calculation module of the synchronization detector 20252 is triggered to calculate the phase, the Cordic phase calculation module uses the Cordic calculation algorithm inside the FPGA control unit 202 to calculate the phase difference of the two alternating power sources (the resolution of the phase difference is 0.1°), and then outputs the phase difference to the register of the FPGA control unit 202 in real time. The register is provided to the switching decision FSM module 2024 for use.

[0067] The Cordic calculation algorithm includes a Cordic phase algorithm and a Cordic iteration algorithm. The Cordic phase algorithm (python language description) is as follows:

[0068]

[0069] The Cordic iteration algorithm (python language description) is as follows:

[0070]

[0071]

[0072] As shown in Figure 10 The application also provides a three-phase static switching switch switching control method, which applies the three-phase static switching switch of the application. The method comprises the following steps:

[0073] Step S1: The FPGA control unit 202 detects whether the main power supply voltage is normal, and if normal, supplies power through the main power supply; the main power supply is the default state;

[0074] Step S2: If it is detected that the main power supply voltage is abnormal (overvoltage, undervoltage or power failure), the driving signal of the IGBT static switch 2032 of the main power supply is locked within 0.5 ms; prevent fault expansion.

[0075] Step S3: Delay 1 ms to confirm whether the main power supply fault is continuous; if the main power supply fault is continuous, proceed to the next step; if the main power supply fault is not continuous, the main power supply continues to supply power;

[0076] Step S4: Detect whether the voltage, frequency and phase parameters of the standby power supply are normal; if normal, proceed to the next step; if not normal, stop power supply;

[0077] Step S5: When the backup power supply voltage crosses zero, the FPGA control unit 202 controls the switching of the IGBT static switch 2032 that turns on the backup power supply to achieve a smooth switching. After the switching is completed, the drive signal of the IGBT static switch of the main power supply is turned off to isolate the fault side.

[0078] The FPGA control unit 202 performs control switching using a zero-current switching algorithm. The zero-current switching algorithm (described in Verilog) is as follows:

[0079]

[0080]

[0081] like Figures 11-13 As shown. During voltage zero-crossing switching, since there are two voltage waveforms, the main power supply and the backup power supply, if the main power supply waveform is a sine wave that reaches the positive half-cycle first and then the negative half-cycle on the time axis, then the backup power supply waveform is also a sine wave, but the phase is different from the main power supply. At this time, there is a switching point located at the intersection (X) of the two waveforms, which is the voltage zero-crossing point. The current waveform remains continuous during the switching process without any abrupt changes, indicating that the switching is smooth. Furthermore, after detecting a fault (t0), the switching signal immediately blocks the drive of the faulty power supply (signal goes low) and then waits for a suitable switching opportunity (voltage zero-crossing point). The time from t0 to t1 is very short (<0.5ms), and the time from t1 to t2 is the waiting time for the zero-crossing point, which does not exceed 10ms (half a cycle). The switching is performed at time t2 (signal goes high, and the backup power supply is turned on).

[0082] The switching control method of the present invention detects the voltage waveform of the backup power AC and triggers the IGBT static switch to turn on when the current approaches the voltage zero crossing point (current approaches zero). The current surge during the switching process is reduced by 90%, reducing voltage fluctuations and electromagnetic interference, and extending the equipment life.

Claims

1. A three-phase static switching switch, characterized in that, include: The input module (1) has two AC power supplies (101); One of the AC power supplies (101) is the main power supply, and the other AC power supply (101) is the backup power supply; The output module (3) is connected to the load (5) and is used to output one AC power supply (101) to the load (5); The control module (2) includes an FPGA control unit (202), a drive circuit unit (203), and a protection circuit unit (201). The FPGA control unit (202) is electrically connected to the drive circuit unit (203) and the protection circuit unit (201). The drive circuit unit (203) includes an optical fiber isolation (2031) and an IGBT static switch (2032). The input end of the optical fiber isolation (2031) is connected to the FPGA control unit (202), and the output end of the optical fiber isolation (2031) is connected to a pair of IGBT static switches (2032). The pair of IGBT static switches (2032) are connected in parallel in reverse. The two AC power supplies (101) are respectively connected to the pair of IGBT static switches (2032). The FPGA control unit (202) is used to control the pair of IGBT static switches (2032) to output one AC power supply (101) to the output module (3).

2. The three-phase static switching switch according to claim 1, characterized in that, The output module (3) includes an output selection switch (301), a three-stage filtering unit (302), and a conductive leakage protection unit (303) connected in series. The three-stage filtering unit (302) is connected to the load (5) and the conductive leakage protection unit (303). The load (5) is connected to the conductive leakage protection unit (303). The output selection switch (301) is connected to a pair of IGBT static switches (2032). The three-stage filtering unit (302) includes a first-stage filtering component (3022), a second-stage filtering component (3023), and a third-stage filtering component (3024). The first-stage filtering component (3022) includes a common-mode choke (30221) and an X capacitor (30222). The common-mode choke (30221) is connected in series on the L line and the N line. The X capacitor... The capacitor (30222) is connected in parallel between the L line and the N line. The secondary filter component (3023) includes a feedthrough filter (30231) and a Y capacitor (30232). The feedthrough filter (30231) is connected in series between the L line and the N line and a common-mode choke (30221). The Y capacitor (30232) is connected between the L line and the PE line and between the N line and the PE line. The tertiary filter component (3024) includes a nanocrystalline magnetic ring (30241) and a three-terminal capacitor (30242). The nanocrystalline magnetic ring (30241) is connected in series between the L line and the N line at the output of the feedthrough filter (30231). The input of the three-terminal capacitor (30242) is connected to the Y capacitor (30232) through the L line and the N line. The output is connected to the load (5) and the conductive leakage protection unit (303).

3. The three-phase static switching switch according to claim 2, characterized in that, The conductive leakage protection circuit (303) includes an isolation transformer (3031), a Y capacitor bank (3032), and a double-shielded cable (3033). The primary winding (30311) of the isolation transformer (3031) is connected to the output terminal of the three-terminal capacitor (30242). The shielding layer (30313) of the isolation transformer (3031) is grounded. The secondary winding (30312) of the isolation transformer (3031) is connected to the Y capacitor bank (3032) in parallel and then grounded. The secondary winding (30312) is also connected to the load (5) through the double-shielded cable (3033).

4. The three-phase static switching switch according to claim 3, characterized in that, The double-shielded cable (3033) includes an inner shielding layer (30331), an outer shielding layer, and an inner conductor. The inner shielding layer (30331) is a copper mesh braided layer that covers the outside of the inner conductor. The outer shielding layer is formed by multiple ferrite magnetic rings (30332) sleeved on the outer periphery of the inner shielding layer (30331). The inner conductor is a twisted pair.

5. The three-phase static switching switch according to claim 1, characterized in that, The input module (1) further includes an EMC filter (103), which is connected in series with the AC power supply (101) and then connected to a pair of IGBT static switches (2032).

6. The three-phase static switching switch according to claim 4, characterized in that, The FPGA control unit includes a CPU (2021), a DESAAT protection control module (2022), a PWM generation module (2023), a switching decision FSM module (2024), and a zero-crossing comparison synchronization detection module (2025). The CPU (2021) is electrically connected to and controls the DESAAT protection control module (2022), the PWM generation module (2023), the switching decision FSM module (2024), and the zero-crossing comparison synchronization detection module (2025), respectively. The zero-crossing comparison synchronization detection module (2025) is used to receive input from the module (…). The sensor signal of 1) is output to the switching decision FSM module (2024) and used to provide a zero-crossing signal to the PWM generation module (2023). The PWM generation module (2023) generates a drive signal to the fiber isolation (2031) according to the decision of the switching decision FSM module (2024) to control the on / off of a pair of IGBT static switches (2032). The DESAT protection control module (2022) is used to receive the protection signal of the protection circuit unit (201) and send the protection signal to the switching decision FSM module (2024).

7. The three-phase static switching switch according to claim 6, characterized in that, The protection circuit unit (201) includes a hardware comparator (2014) and a DESAT detection and protection module (2015). The DESAT detection and protection module (2015) and the hardware comparator (2014) are used to send protection signals to the DESAT protection control module (2022) when there is overcurrent, overvoltage, or overtemperature.

8. The three-phase static switching switch according to claim 7, characterized in that, The zero-crossing comparison synchronization detection module (2025) includes a zero-crossing comparator (20251) and a synchronization detector (20252). The zero-crossing comparator (20251) is used to detect the sensor signal of the AC power supply (101). When the sensor signal crosses zero, the synchronization detector (20252) is triggered to perform phase calculation to obtain the phase difference of a pair of AC power supplies (101). The switching decision FSM module (2024) generates a drive signal based on the phase difference.

9. A switching control method for a three-phase static transfer switch, using the three-phase static transfer switch as described in any one of claims 1-8, characterized in that, The control method includes the following steps: Step S1: Check if the main power supply is normal. If it is normal, supply power through the main power supply. Step S2: If the main power supply is abnormal, the drive signal of the IGBT static switch (2032) of the main power supply will be blocked within a predetermined time. Step S3: Delay for a certain period of time to confirm whether the main power failure continues; if it continues, proceed to the next step. Step S4: Check if the backup power supply is normal. If it is normal, continue to the next step. Step S5: Turn on the IGBT static switch (2032) of the backup power supply at the zero-crossing point of the backup power supply voltage; Step S6: Turn off the IGBT static switch (2032) of the main power supply.

10. The three-phase static switching switch switching control method according to claim 9, characterized in that, The voltage zero-crossing point is the intersection of the voltage waveform of the main power supply and the voltage waveform of the backup power supply.

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