Short-circuit protection system for bidirectional traction converter and bidirectional traction converter

Abstract

This invention provides a short-circuit protection system for a bidirectional traction converter and the bidirectional traction converter itself. The device includes at least one bidirectional converter; the system includes a short-circuit detection circuit, a bypass drive circuit, a controller, and a bypass protection device connected in parallel with the bidirectional converter; the short-circuit detection circuit performs short-circuit detection based on the current signal at the DC terminal of the bidirectional converter and the traction voltage signal of the DC traction contact network, and transmits the short-circuit detection result to the bypass drive circuit and the controller; when the short-circuit detection result indicates a short-circuit fault, the bypass drive circuit drives the bypass protection device to operate; when the short-circuit detection result indicates a short-circuit fault, the controller controls the bidirectional converter to stop operating and controls the first and second switches to open. This application can prevent the body diode of the bidirectional converter from bearing a large short-circuit current, avoid damage to the components inside the bidirectional converter, and improve the reliability of the short-circuit protection system.

Description

Technical Field

[0001] This invention relates to the field of short-circuit protection technology, and in particular to a short-circuit protection system for a bidirectional traction converter and the bidirectional traction converter itself. Background Technology

[0002] The rail transit traction power supply system provides power to rail transit vehicles and other loads, and typically includes a bidirectional traction converter. The bidirectional traction converter enables energy flow between the AC power grid and the DC traction contact network. To provide short-circuit protection for the bidirectional traction converter, a bypass protection device is installed for the bidirectional converter within the system.

[0003] Currently, short-circuit faults are detected by controller software. When a short-circuit fault occurs, to protect the bidirectional converter, the software typically disables the bidirectional converter's drive and switches to bypass protection. However, controller chip resources are limited. In product design, the control of the normal main power topology (i.e., the control of the bidirectional converter) has the highest priority. Furthermore, software detection of short-circuit faults takes time. This means that for a certain period, the IGBTs in the bidirectional converter are disabled from driving, while the bypass protection has not yet activated. The large short-circuit current can only flow through the body diodes of the bidirectional converter's IGBTs, and body diodes have limited current-carrying capacity, posing a significant risk of device damage. If short-circuit protection is applied when a short-circuit fault occurs, but the devices within the bidirectional converter still fail, then the short-circuit protection is essentially ineffective and fails to achieve its purpose. Summary of the Invention

[0004] This invention provides a short-circuit protection system for a bidirectional traction converter and a bidirectional traction converter, to solve the problem that software control requires time and the control of the normal main power topology occupies the highest priority, which may lead to a large risk of device damage.

[0005] In a first aspect, embodiments of the present invention provide a short-circuit protection system for a bidirectional traction converter. The bidirectional traction converter includes at least one bidirectional converter. The AC terminal of the bidirectional converter is connected to an AC bus via a first switch, and the DC terminal of the bidirectional converter is connected to a DC traction contact network via a second switch.

[0006] The short-circuit protection system includes a short-circuit detection circuit, a bypass drive circuit, a controller, and a bypass protection device connected in parallel with the bidirectional converter;

[0007] The short-circuit detection circuit is used to perform short-circuit detection based on the current signal at the DC end of the bidirectional converter and the traction voltage signal of the DC traction contact network, and transmits the short-circuit detection result to the bypass drive circuit and controller.

[0008] When the short circuit detection result indicates a short circuit fault, the bypass drive circuit drives the bypass protection device to operate.

[0009] When the short-circuit detection result indicates a short-circuit fault, the controller stops the bidirectional converter from working and disconnects the first and second switches.

[0010] Secondly, embodiments of the present invention provide a bidirectional traction converter, including a short-circuit protection system for the bidirectional traction converter as described in the first aspect or any possible implementation thereof.

[0011] Thirdly, embodiments of the present invention provide a rail transit traction power supply system, including the bidirectional traction converter as described in the second aspect.

[0012] This invention provides a short-circuit protection system for a bidirectional traction converter and the bidirectional traction converter itself. The short-circuit protection system detects short-circuit faults via a short-circuit detection circuit. When a short-circuit fault occurs, a bypass drive circuit activates a bypass protection device. A controller stops the bidirectional converter when a short-circuit fault occurs. This allows for rapid detection of short-circuit faults and activation of the bypass protection device through hardware detection and hardware drive, while software control stops the bidirectional converter. Since hardware control is faster than software control, the bypass protection device will not start operating later than the bidirectional converter stops operating when a short-circuit fault occurs. This prevents the body diodes of the bidirectional converter from experiencing large short-circuit currents, avoids damage to components within the bidirectional converter, and improves the reliability of the short-circuit protection system. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the short-circuit protection system of the bidirectional traction converter provided in an embodiment of the present invention;

[0015] Figure 2 This is a schematic diagram of the structure of the rail transit traction power supply system provided in an embodiment of the present invention;

[0016] Figure 3 This is a schematic diagram of the signal isolation module provided in an embodiment of the present invention;

[0017] Figure 4 This is a schematic diagram of the short-circuit slow detection module provided in an embodiment of the present invention;

[0018] Figure 5 This is a schematic diagram of the bypass drive circuit provided in an embodiment of the present invention;

[0019] Figure 6 This is a schematic diagram of the short-circuit comprehensive judgment module provided in an embodiment of the present invention;

[0020] Figure 7 This is a schematic diagram of the short-circuit fast detection module provided in an embodiment of the present invention. Detailed Implementation

[0021] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0023] Figure 1 This diagram illustrates the structure of the short-circuit protection system of the bidirectional traction converter provided in an embodiment of the present invention. Figure 2 A schematic diagram of the structure of a rail transit traction power supply system provided in an embodiment of the present invention is shown. See also... Figure 1 and Figure 2 The bidirectional traction converter includes at least one bidirectional converter 11. The AC terminal of the bidirectional converter 11 is connected to the AC bus 12 through the first switch QF1, and the DC terminal of the bidirectional converter 11 is connected to the DC traction contact network 13 through the second switch QF2.

[0024] The short-circuit protection system of the bidirectional traction converter includes a short-circuit detection circuit 21, a bypass drive circuit 22, a controller 23, and a bypass protection device 24 connected in parallel with the bidirectional converter 11.

[0025] The short-circuit detection circuit 21 is used to detect the current signal at the DC terminal of the bidirectional converter 11 and the traction voltage signal V of the DC traction contact network 13. 牵引 Perform short circuit detection and transmit the short circuit detection result Vout to the bypass drive circuit 22 and the controller 23;

[0026] When the short circuit detection result indicates that a short circuit fault has occurred, the bypass drive circuit 22 drives the bypass protection device 24 to operate.

[0027] When the short circuit detection result indicates a short circuit fault, the controller 23 controls the bidirectional converter 11 to stop working and controls the first switch QF1 and the second switch QF2 to open.

[0028] See Figure 1 Each bidirectional converter 11 and bypass protection device 24 corresponds to a specific bidirectional converter 11. When a short-circuit fault is detected, the bidirectional converter 11 stops working, and the corresponding bypass protection device 24 starts working. This embodiment does not impose a specific limit on the number of bidirectional converters 11 included in the bidirectional traction converter device, and can be set according to actual needs. Figure 1 An example of a bidirectional traction converter device comprising two bidirectional converters 11 is given.

[0029] When a bidirectional traction converter includes at least two bidirectional converters 11, the bidirectional converters 11 are connected in parallel. Each bidirectional converter 11 can operate simultaneously, or some bidirectional converters 11 can operate simultaneously while the remaining bidirectional converters 11 serve as backups. When a working bidirectional converter 11 fails, the backup bidirectional converter 11 takes over. For example, if the bidirectional traction converter includes two bidirectional converters 11, both bidirectional converters 11 can operate simultaneously, or one bidirectional converter 11 can operate while the other serves as a backup. When the working bidirectional converter 11 fails, the backup bidirectional converter 11 takes over.

[0030] In this embodiment, the short-circuit detection circuit 21 is electrically connected to the controller 23, the bypass drive circuit 22, the DC terminal of the bidirectional converter 11, and the DC traction contact network 13, respectively; the bypass drive circuit 22 is signal-connected to the bypass protection device 24; the controller 23 is signal-connected to the bidirectional converter 11, the first switch QF1, and the second switch QF2, respectively. The bidirectional converter 11, the first switch QF1, and the second switch QF2 are controlled by the controller 23, and the bypass protection device 24 is controlled by the bypass drive circuit 22.

[0031] The first switch QF1 and the second switch QF2 can be circuit breakers or other types of switches, without specific restrictions.

[0032] The short-circuit detection circuit 21 can acquire the current signal at the DC terminal of the bidirectional converter 11 and the traction voltage signal of the DC traction contact network 13, and determine the appropriate voltage based on the current signal at the DC terminal of the bidirectional converter 11 and the traction voltage signal V of the DC traction contact network 13. 牵引The system performs short-circuit detection to determine if a short-circuit fault has occurred and transmits the short-circuit detection result Vout to the bypass drive circuit 22 and the controller 23. When the short-circuit detection result indicates a short-circuit fault, the bypass drive circuit 22 drives the bypass protection device 24 to operate. When the short-circuit detection result indicates a short-circuit fault, the controller 23 controls the bidirectional converter 11 to stop operating by blocking its drive, and controls the first switch QF1 and the second switch QF2 to open. When a short-circuit fault occurs, the short-circuit current can be discharged through the bypass protection device 24.

[0033] The current signal at the DC terminal of the bidirectional converter 11 can be understood as the current signal at the DC terminal of all bidirectional converters 11 connected in parallel. The traction voltage signal V of the DC traction contact network 13... 牵引 This can be understood as the DC voltage signal after all bidirectional converters 11 are connected in parallel.

[0034] The short-circuit protection system in this embodiment detects whether a short-circuit fault has occurred through the short-circuit detection circuit 21. When a short-circuit fault occurs, the bypass drive circuit 22 drives the bypass protection device 24 to work. When a short-circuit fault occurs, the controller 23 controls the bidirectional converter 11 to stop working. Thus, short-circuit faults can be quickly detected and the bypass protection device 24 can be driven to work through hardware detection and hardware drive. The bidirectional converter 11 can be stopped by software control. Since the speed of hardware control is faster than that of software control, the time when the bypass protection device 24 starts working when a short-circuit fault occurs will not be later than the time when the bidirectional converter 11 stops working. This can prevent the body diode of the bidirectional converter 11 from being subjected to a large short-circuit current, avoid damage to the components inside the bidirectional converter 11, and improve the reliability of the short-circuit protection system.

[0035] In some embodiments, see Figure 1 The short circuit detection circuit 21 includes a current acquisition module 211, a signal isolation module 212, a fast short circuit detection module 213, a slow short circuit detection module 214, and a short circuit comprehensive judgment module 215.

[0036] The current acquisition module 211 is used to acquire the current signal at the DC terminal of the bidirectional converter 11 and convert the current signal at the DC terminal of the bidirectional converter 11 into a first voltage signal Vin.

[0037] The signal isolation module 212 is used to amplify and isolate the first voltage signal Vin transmitted by the current acquisition module 211 to obtain the second voltage signal Vin1;

[0038] The short-circuit fast detection module 213 is used to detect short circuits based on the traction voltage signal V. 牵引 The second voltage signal Vin1 transmitted by the signal isolation module 212 is used to determine whether a near-end short circuit fault has occurred, and a near-end short circuit fault detection signal is obtained.

[0039] The short-circuit slow detection module 214 is used to detect traction voltage signal V. 牵引 The second voltage signal Vin1 transmitted by the signal isolation module 212 is used to determine whether a remote short circuit fault has occurred, and a remote short circuit fault detection signal is obtained.

[0040] The short-circuit comprehensive judgment module 215 is used to determine the short-circuit detection result Vout based on the near-end short-circuit fault detection signal transmitted by the short-circuit fast detection module 213 and the far-end short-circuit fault detection signal transmitted by the short-circuit slow detection module 214.

[0041] See Figure 1 The current acquisition module 211 is connected to the signal isolation module 212 and the DC terminal of the bidirectional converter 11. The signal isolation module 212 is also connected to the short-circuit fast detection module 213 and the short-circuit slow detection module 214. Both the short-circuit fast detection module 213 and the short-circuit slow detection module 214 are connected to the short-circuit comprehensive judgment module 215. The short-circuit comprehensive judgment module 215 is also connected to the controller 23 and the bypass drive circuit 22. The short-circuit fast detection module 213 and the short-circuit slow detection module 214 can also be connected to the DC traction contact network 13 to acquire the traction voltage signal V of the DC traction contact network 13. 牵引 .

[0042] The current acquisition module 211 may include a shunt or a Hall current sensor. The shunt or Hall current sensor can withstand large short-circuit currents, such as a 50kA inrush current.

[0043] After determining the short circuit detection result Vout, the short circuit comprehensive judgment module 215 transmits the short circuit detection result Vout to the bypass drive circuit 22 and the controller 23.

[0044] In some embodiments, if the second voltage signal is greater than the first voltage threshold signal and the traction voltage signal is less than the second voltage threshold signal, then a near-end short-circuit fault is determined to have occurred; otherwise, it is determined that no near-end short-circuit fault has occurred.

[0045] If, within a preset time period, the absolute value of the change in the second voltage signal is greater than the first voltage change threshold and the absolute value of the change in the traction voltage signal is greater than the second voltage change threshold, then a remote short circuit fault is determined to have occurred; otherwise, it is determined that no remote short circuit fault has occurred.

[0046] If the near-end short-circuit fault detection signal indicates a near-end short-circuit fault, or the far-end short-circuit fault detection signal indicates a far-end short-circuit fault, then the short-circuit detection result is determined to be a short-circuit fault; otherwise, the short-circuit detection result is determined to be no short-circuit fault.

[0047] See Figure 2Using this station (i.e., the current station) as the reference, short-circuit faults within the bidirectional traction converter of this station, short-circuit faults within adjacent stations (i.e., the previous station 1 and the next station 1), and short-circuit faults between this station and adjacent stations are all referred to as near-end short-circuit faults. Short-circuit faults within other stations (i.e., from the previous station 2 to the previous station n, and from the next station 2 to the next station n), and short-circuit faults between other stations are referred to as far-end short-circuit faults. The value of n can be determined based on the actual number of stations.

[0048] The first voltage threshold signal, the second voltage threshold signal, the preset duration, the first voltage change threshold, and the second voltage change threshold can be set according to actual needs, and no specific restrictions are imposed here.

[0049] See Figure 2 The DC end of the bidirectional converter 11 is connected to the DC traction contact network 13 and the return rail 14 respectively through the second switch.

[0050] In some embodiments, see Figure 3 The signal isolation module 212 includes an amplification unit 2121 and an isolation unit 2122;

[0051] The input terminal of the amplification unit 2121 is connected to the input terminal of the signal isolation module 212, and the output terminal of the amplification unit 2121 is connected to the input terminal of the isolation unit 2122.

[0052] The output terminal of isolation unit 2122 is connected to the output terminal of signal isolation module 212;

[0053] The signal isolation module 212 receives a first voltage signal Vin at its input terminal and outputs a second voltage signal Vin1 at its output terminal.

[0054] In some embodiments, see Figure 3 The amplification unit 2121 includes a first operational amplifier A1, a first capacitor C1, a second capacitor C2, a third capacitor C3, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4.

[0055] The first input terminal of the first operational amplifier A1 is connected to the input terminal of the amplification unit 2121 through the second resistor R2, and is connected to the first ground terminal 0V1 through the first capacitor C1 and the first resistor R1 connected in parallel, and is connected to the second input terminal of the first operational amplifier A1 through the second capacitor C2.

[0056] The second input terminal of the first operational amplifier A1 is connected to the first ground terminal 0V1 through the third resistor R3, and is connected to the output terminal of the first operational amplifier A1 through the third capacitor C3 and the fourth resistor R4 connected in parallel.

[0057] The output terminal of the first operational amplifier A1 is connected to the output terminal of the amplification unit 2121.

[0058] In some embodiments, see Figure 3 The isolation unit 2122 includes an isolation amplifier IC1, a second operational amplifier A2, a first anti-sulfurization resistor RS1, a second anti-sulfurization resistor RS2, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a first diode D1, and a second diode D2.

[0059] The first input terminal (pin 2) of isolation amplifier IC1 is connected to the input terminal of isolation unit 2122 through the first anti-sulfurization resistor RS1, connected to the first ground terminal 0V1 through the fourth capacitor C4 and the sixth resistor R6 connected in parallel, and connected to the first voltage terminal +5V_DC through the fifth resistor R5; the second input terminal (pin 3) of isolation amplifier IC1 is connected to the first ground terminal 0V1 through the second anti-sulfurization resistor RS2, connected to the first ground terminal 0V1 through the ninth capacitor C9 and the eighth resistor R8 connected in parallel, and connected to the first voltage terminal +5V_DC through the seventh resistor R7; the first power supply terminal (pin 1) of isolation amplifier IC1 is connected to the first voltage terminal +5V_DC, so that... The isolation amplifier IC1 is connected to the first ground terminal (pin 4) of the isolation amplifier IC1 via the fifth capacitor C5; the first ground terminal of the isolation amplifier IC1 is connected to the first ground terminal 0V1; the first output terminal (pin 7) of the isolation amplifier IC1 is connected to the first input terminal of the second operational amplifier A2 via the ninth resistor R9; the second output terminal (pin 6) of the isolation amplifier IC1 is connected to the second input terminal of the second operational amplifier A2 via the tenth resistor R10; the second power supply terminal (pin 8) of the isolation amplifier IC1 is connected to the second voltage terminal +5V_D, and is connected to the second ground terminal (pin 5) of the isolation amplifier IC1 via the sixth capacitor C6; the second ground terminal of the isolation amplifier IC1 is connected to the second ground terminal 0V.

[0060] The first input terminal of the second operational amplifier A2 is connected to the second ground terminal 0V through the eleventh capacitor C11 and the eleventh resistor R11 connected in parallel, and is also connected to the second input terminal of the second operational amplifier A2 through the seventh capacitor C7; the second input terminal of the second operational amplifier A2 is connected to the output terminal of the second operational amplifier A2 through the tenth capacitor C10 and the twelfth resistor R12 connected in parallel; the output terminal of the second operational amplifier A2 is connected to the output terminal of the isolation unit 2122 through the thirteenth resistor R13.

[0061] The output terminal of the isolation unit 2122 is connected to the third voltage terminal +3.3V_A through the first diode D1, to the second ground terminal 0V through the second diode D2, and to the second ground terminal 0V through the fourteenth resistor R14 and the eighth capacitor C8 connected in parallel.

[0062] See Figure 3 The number of the first anti-sulfurization resistor RS1 and the second anti-sulfurization resistor RS2 can be set according to actual needs; there can be one or more, and no specific restrictions are imposed here.

[0063] The first grounding terminal 0V1 and the second grounding terminal 0V are isolated from each other. The first voltage terminal +5V_DC can provide 5V. The second voltage terminal +5V_D can provide 5V. The third voltage terminal +3.3V_A can provide 3.3V.

[0064] It should be noted that the voltages provided by the voltage terminals in the embodiments of this application are merely illustrative examples. In practical applications, they can be adjusted according to actual needs, and no specific limitations are made here.

[0065] In some embodiments, see Figure 4 The short-circuit slow detection module 214 includes a first voltage slow detection unit 2141, a second voltage slow detection unit 2142, and a first AND gate Y1;

[0066] The input terminal of the first voltage slow detection unit 2141 is connected to the first input terminal of the short-circuit slow detection module 214, and the output terminal of the first voltage slow detection unit 2141 is connected to the first input terminal of the first AND gate Y1. The first voltage slow detection unit 2141 is used to detect whether the absolute value of the change in the second voltage signal is greater than the first voltage change threshold within a preset time period.

[0067] The input terminal of the second voltage slow detection unit 2142 is connected to the second input terminal of the short circuit slow detection module 214, and the output terminal of the second voltage slow detection unit 2142 is connected to the second input terminal of the first AND gate Y1. The second voltage slow detection unit 2142 is used to detect whether the absolute value of the change in the traction voltage signal within a preset time period is greater than the second voltage change threshold.

[0068] The output of the first AND gate Y1 is connected to the output of the short-circuit slow detection module 214;

[0069] The first input terminal of the short-circuit slow detection module 214 is used to input the second voltage signal Vin1, and the second input terminal of the short-circuit slow detection module 214 is used to input the traction voltage signal V. 牵引 The output of the short-circuit slow detection module 214 is used to output a remote short-circuit fault detection signal V. 慢检 .

[0070] In some embodiments, see Figure 4 The first voltage slow detection unit 2141 includes a first sample-and-hold subunit MJ1, a first difference subunit MJ2, a first absolute value calculation subunit MJ3, and a first comparison subunit MJ4 connected in sequence; the first sample-and-hold subunit MJ1 includes a first sample-and-hold circuit CB1, a second sample-and-hold circuit CB2, a twelfth capacitor C12, and a thirteenth capacitor C13; the first difference subunit MJ2 includes a third operational amplifier A3, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, and an eighteenth resistor R18; the first absolute value calculation subunit MJ3 includes a fourth operational amplifier A4, a fifth operational amplifier A5, a third diode D3, a fourth diode D4, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, a twenty-second resistor R22, a twenty-third resistor R23, and a twenty-fourth resistor R24; the first comparison subunit MJ4 includes a sixth operational amplifier A6 and a twenty-fifth resistor R25.

[0071] The first input terminal of the first sample-and-hold circuit CB1 is connected to the input terminal of the first voltage slow detection unit 2141, and the second input terminal of the first sample-and-hold circuit CB1 is connected to the fourth voltage terminal V1; the output terminal of the first sample-and-hold circuit CB1 is connected to the second ground terminal 0V through the twelfth capacitor C12, and is connected to the first input terminal of the third operational amplifier A3 through the fifteenth resistor R15; the fourth voltage terminal V1 provides the first reference voltage;

[0072] The first input terminal of the second sample-and-hold circuit CB2 is connected to the input terminal of the first voltage slow detection unit 2141, and the second input terminal of the second sample-and-hold circuit CB2 is connected to the fifth voltage terminal V2; the output terminal of the second sample-and-hold circuit CB2 is connected to the second ground terminal 0V through the thirteenth capacitor C13, and is connected to the second input terminal of the third operational amplifier A3 through the sixteenth resistor R16; the fourth voltage terminal V1 provides the second reference voltage;

[0073] The first input terminal of the third operational amplifier A3 is connected to the output terminal of the third operational amplifier A3 through the seventeenth resistor R17. The second input terminal of the third operational amplifier A3 is connected to the second ground terminal 0V through the eighteenth resistor R18. The output terminal of the third operational amplifier A3 is connected to the first input terminal of the fourth operational amplifier A4 through the nineteenth resistor R19. The first input terminal of the fourth operational amplifier A4 is connected to the first input terminal of the fifth operational amplifier A5 through the twentieth resistor R20. The second input terminal of the fourth operational amplifier A4 is connected to the second ground terminal 0V through the twenty-first resistor R21, connected to the output terminal of the fourth operational amplifier A4 through the third diode D3, and connected to the output terminal of the fourth operational amplifier A4 through the twenty-second resistor R22 and the fourth diode D4 connected in series.

[0074] The second input terminal of the fifth operational amplifier A5 is connected to the midpoint of the twenty-second resistor R22 and the fourth diode D4 through the twenty-third resistor R23, and is connected to the output terminal of the fifth operational amplifier A5 through the twenty-fourth resistor R24; the output terminal of the fifth operational amplifier A5 is connected to the first input terminal of the sixth operational amplifier A6; the second input terminal of the sixth operational amplifier A6 is connected to the sixth voltage terminal Vth1; the output terminal of the sixth operational amplifier A6 is connected to the second ground terminal 0V through the twenty-fifth resistor R25, and is connected to the output terminal of the first voltage slow detection unit 2141; the sixth voltage terminal Vth1 provides the first voltage change threshold.

[0075] The magnitudes of the first and second reference voltages can be set according to actual needs, and no specific restrictions are imposed here.

[0076] The anode of the third diode D3 is connected to the output terminal of the fourth operational amplifier A4, and the cathode of the third diode D3 is connected to the second input terminal of the fourth operational amplifier A4. The anode of the fourth diode D4 is connected to the second input terminal of the fourth operational amplifier A4 through the twenty-second resistor R22, and the cathode of the fourth diode D4 is connected to the output terminal of the fourth operational amplifier A4. The midpoint between the twenty-second resistor R22 and the fourth diode D4 is their connection point.

[0077] See Figure 4 The second voltage slow detection unit 2142 includes a second sample and hold subunit MJ5, a second difference subunit MJ6, a second absolute value calculation subunit MJ7, and a second comparison subunit MJ8 connected in sequence.

[0078] The second sample-and-hold subunit MJ5 has the same structure as the first sample-and-hold subunit MJ1, except that the input parameters and the reference voltage of the sample-and-hold circuit are different. The input parameter of the second sample-and-hold subunit MJ5 is the traction voltage signal V. 牵引 The corresponding reference voltage can be set according to actual needs.

[0079] The second difference subunit MJ6 has the same structure as the first difference subunit MJ2; the second absolute value calculation subunit MJ7 has the same structure as the first absolute value calculation subunit MJ3; the second comparison subunit MJ8 has the same structure as the first comparison subunit MJ4, except that the voltage change thresholds for comparison are different. In the second comparison subunit MJ8, the output parameters of the second absolute value calculation subunit MJ7 are compared with the second voltage change threshold.

[0080] The specific implementation structure of the second voltage slow detection unit 2142 will not be described in detail in this embodiment; please refer to [reference needed]. Figure 4 Related descriptions of the first voltage slow detection unit 2141.

[0081] In some embodiments, see Figure 1 The bypass protection device 24 includes an A-phase controllable switch bridge arm, a B-phase controllable switch bridge arm, and a C-phase controllable switch bridge arm.

[0082] The midpoints of the A-phase controllable switch bridge arm, the B-phase controllable switch bridge arm, and the C-phase controllable switch bridge arm are all connected to the AC terminals of the bypass protection device and the corresponding bidirectional converters. The two ends of the A-phase controllable switch bridge arm, the two ends of the B-phase controllable switch bridge arm, and the two ends of the C-phase controllable switch bridge arm are all connected to the DC terminals of the bypass protection device and the corresponding bidirectional converters.

[0083] In this configuration, the A-phase controllable switch arm, the B-phase controllable switch arm, and the C-phase controllable switch arm can each consist of two thyristors connected in series, with one thyristor serving as the upper arm of the corresponding phase and the other as the lower arm. The connection point between the two thyristors is the midpoint of the corresponding arm.

[0084] The midpoint of the A-phase controllable switch bridge arm is connected to the AC A-phase terminal of the corresponding bidirectional converter, the midpoint of the B-phase controllable switch bridge arm is connected to the AC B-phase terminal of the corresponding bidirectional converter, and the midpoint of the C-phase controllable switch bridge arm is connected to the AC C-phase terminal of the corresponding bidirectional converter.

[0085] In some embodiments, see Figure 5 The bypass drive circuit 22 includes a square wave generator 224;

[0086] Square wave generator 224 is used to continuously output square wave signals;

[0087] The bypass drive circuit 22 is used to generate a drive signal based on the square wave signal to drive the bypass protection device 24 to work when the short circuit detection result indicates that a short circuit fault has occurred; and to block the square wave signal when the short circuit detection result indicates that no short circuit fault has occurred.

[0088] In this embodiment, the square wave generator 224 can continuously emit a square wave signal. Once a short circuit fault is detected, the bypass drive circuit 22 can generate a drive signal for driving the bypass protection device 24 based on the square wave signal, thereby quickly driving the bypass protection device 24 to work when a short circuit fault is detected, reducing waiting time; when no short circuit fault occurs, the bypass drive circuit 22 blocks the square wave signal and does not generate the drive signal.

[0089] In some embodiments, see Figure 5 The bypass drive circuit 22 also includes an A-phase drive sub-circuit 221, a B-phase drive sub-circuit 222, and a C-phase drive sub-circuit 223.

[0090] Phase A drive sub-circuit 221 includes a second AND gate Y2, a third AND gate Y3, a transformer T1, a switching transistor Q1, a 26th resistor R26, a 27th resistor R27, a 14th capacitor C14, a 28th resistor R28, a 15th capacitor C15, a 29th resistor R29, a 30th resistor R30, a 31st resistor R31, a 16th capacitor C16, a 32nd resistor R32, a first transistor VT1, a 33rd resistor R33, a 34th resistor R34, a 17th capacitor C17, an 18th capacitor C18, a 19th capacitor C19, a 35th resistor R35, a 36th resistor R36, a fifth diode D5, and a sixth diode D6.

[0091] The short-circuit detection result Vout is input to the first input terminal of the second AND gate Y2 through the twenty-sixth resistor R26; the first input terminal of the second AND gate Y2 is connected to the second ground terminal 0V through the twenty-seventh resistor R27 and the fourteenth capacitor C14 connected in parallel; the second input terminal of the second AND gate Y2 is connected to the power-on blocking signal FS through the twenty-eighth resistor R28, to the seventh voltage terminal V3 through the twenty-ninth resistor R29, to the second ground terminal 0V through the fifteenth capacitor C15, and to the first terminal of the thirty-first resistor R31 and the base of the first transistor VT1 through the thirtieth resistor R30; the thirty-first resistor R31... The second terminal is connected to the seventh voltage terminal V3 and the emitter of the first transistor VT1, respectively; the collector of the first transistor VT1 is connected to the output terminal of the second AND gate Y2 through the thirty-second resistor R32, connected to the second ground terminal 0V through the sixteenth capacitor C16, and connected to the first input terminal of the third AND gate Y3; the second input terminal of the third AND gate Y3 is connected to the output terminal of the square wave generator 224; the output terminal of the third AND gate Y3 is connected to the control terminal of the switch Q1 through the thirty-third resistor R33; the control terminal of the switch Q1 is connected to the second ground terminal 0V and the first terminal of the switch Q1 through the thirty-fourth resistor R34, respectively.

[0092] The first end of the primary winding of transformer T1 is connected to the seventh voltage terminal V3, and is connected to the second ground terminal 0V through the seventeenth capacitor C17; the second end of the primary winding of transformer T1 is connected to the second end of the switching transistor Q1; the two ends of the first secondary winding of transformer T1 connected in series with the thirty-fifth resistor R35 serve as the first output terminal and the second output terminal, respectively; the eighteenth capacitor C18 and the fifth diode D5 are both connected between the first output terminal and the second output terminal; the two ends of the second secondary winding of transformer T1 connected in series with the thirty-sixth resistor R36 serve as the third output terminal and the fourth output terminal, respectively; the nineteenth capacitor C19 and the sixth diode D6 are both connected between the third output terminal and the fourth output terminal; the first and second output terminals are used to output the drive signal of the thyristor of the upper arm of phase A of the three-phase thyristor rectifier bridge; the third and fourth output terminals are used to output the drive signal of the thyristor of the lower arm of phase A of the three-phase thyristor rectifier bridge.

[0093] The seventh voltage terminal V3 can provide 12V voltage.

[0094] Phase A drive sub-circuit 221 is used to output the drive signal of the phase A controllable switch bridge arm, phase B drive sub-circuit 222 is used to output the drive signal of the phase B controllable switch bridge arm, and phase C drive sub-circuit 223 is used to output the drive signal of the phase C controllable switch bridge arm.

[0095] Square wave generator 224 is used to output a square wave signal. See also Figure 5 The square wave generator 224 may include a timer chip (NE555P) and some resistors, capacitors, diodes, etc. For specific connection relationships, please refer to [link / reference needed]. Figure 5 I will not go into details.

[0096] Other structures or devices in the A-phase drive sub-circuit 221 can be referred to... Figure 5 I will not go into details.

[0097] The structures of phase B driver sub-circuit 222 and phase C driver sub-circuit 223 can be referenced from the relevant description of phase A driver sub-circuit 221. Figure 5 I will not go into details.

[0098] The power-on blocking signal FS is a software control signal. When the power-on blocking signal FS is active, the bypass drive circuit 22 is blocked and can no longer drive the bypass protection device 24.

[0099] In some embodiments, see Figure 6 The short-circuit comprehensive judgment module 215 may include a fourth AND gate Y4, a second transistor VT2, a thirty-seventh resistor R37, a thirty-eighth resistor R38, and a twentieth capacitor C20;

[0100] The first input of the fourth AND gate Y4 is used to input the near-end short-circuit fault detection signal V. 快检 The first input of the fourth AND gate Y4 is used to input the remote short-circuit fault detection signal V. 慢检 The output of the fourth AND gate Y4 is connected to the base of the second transistor VT2 through the thirty-seventh resistor R37. The base of the second transistor VT2 is also connected to the emitter of the second transistor VT2 and the second ground terminal 0V through the thirty-eighth resistor R38 and the twentieth capacitor C20 connected in parallel. The collector of the second transistor VT2 is used to output the short circuit detection result Vout.

[0101] In some embodiments, see Figure 7 The short-circuit fast detection module 213 includes a first voltage fast detection unit 2131, a second voltage fast detection unit 2132, and a fifth AND gate Y5;

[0102] The input terminal of the first voltage fast detection unit 2131 is connected to the first input terminal of the short circuit fast detection module 213, and the output terminal of the first voltage fast detection unit 2131 is connected to the first input terminal of the fifth AND gate Y5. The first voltage fast detection unit 2131 is used to detect whether the second voltage signal Vin1 is greater than the first voltage threshold signal Vref1.

[0103] The input terminal of the second voltage fast detection unit 2132 is connected to the second input terminal of the short-circuit fast detection module 213, and the output terminal of the second voltage fast detection unit 2132 is connected to the second input terminal of the fifth AND gate Y5. The second voltage fast detection unit 2132 is used to detect the traction voltage signal V. 牵引 Is it less than the second voltage threshold signal Vref2?

[0104] The output of the fifth AND gate Y5 is connected to the output of the short-circuit fast detection module 213;

[0105] The first input terminal of the short-circuit fast detection module 213 is used to input the second voltage signal Vin1, and the second input terminal of the short-circuit fast detection module 213 is used to input the traction voltage signal V. 牵引 The output of the short-circuit fast detection module 213 is used to output a near-end short-circuit fault detection signal V. 快检 .

[0106] See Figure 7 The first voltage fast detection unit 2131 includes a first comparator B1 and some resistors, capacitors, diodes, and Zener diodes, etc. The connection relationships are shown in [reference needed]. Figure 7 The details will not be elaborated further. The second voltage fast detection unit 2132 includes a second comparator B2 and some resistors, voltage divider resistors, capacitors, diodes, and Zener diodes, etc. The connection relationship is shown in [reference]. Figure 7 This will not be elaborated further. Due to the traction voltage signal V... 牵引The voltage is relatively large, so the second voltage fast detection unit 2132 can be equipped with multiple voltage dividing resistors for voltage division.

[0107] For example, see Figures 4 to 7 When the second voltage signal is greater than the first voltage threshold signal and the traction voltage signal is less than the second voltage threshold signal, the near-end short-circuit fault detection signal V... 快检 The signal level is flipped to low; when the absolute value of the change in the second voltage signal is greater than the first voltage change threshold and the absolute value of the change in the traction voltage signal is greater than the second voltage change threshold within a preset time period, the remote short-circuit fault detection signal V... 慢检 This achieves a level flip, changing the level to low.

[0108] When the near-end short-circuit fault detection signal V 快检 The signal is low, or a remote short-circuit fault detection signal V. 慢检 When the level is low, the short-circuit detection result Vout is flipped to output a high level.

[0109] When the short-circuit detection result Vout is high, the square wave signal output by the square wave generator 224 is used to generate a drive signal through the switching transistor, transformer and other devices to drive the bypass protection device 24 to work.

[0110] The short-circuit protection system provided in this application can provide reliable short-circuit protection for bidirectional traction converters and can adapt to the requirements of different power levels for the number of converter cabinets (i.e., bidirectional converters 11).

[0111] Corresponding to the short-circuit protection system of the bidirectional traction converter, this application embodiment also provides a bidirectional traction converter, including any of the above-mentioned short-circuit protection systems of the bidirectional traction converter, and possessing the beneficial effects of any of the above-mentioned short-circuit protection systems of the bidirectional traction converter.

[0112] Corresponding to the above-mentioned bidirectional traction converter, this application embodiment also provides a rail transit traction power supply system, including the above-mentioned bidirectional traction converter, which has the beneficial effects of the above-mentioned bidirectional traction converter.

[0113] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0114] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0115] In the embodiments provided by this invention, it should be understood that the disclosed apparatus / system and method can be implemented in other ways. For example, the apparatus / system embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0116] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0117] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0118] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the short-circuit protection system embodiments of the various bidirectional traction converters described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0119] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A short-circuit protection system for a bidirectional traction converter, characterized in that, The bidirectional traction converter includes at least one bidirectional converter. The AC terminal of the bidirectional converter is connected to the AC bus via a first switch, and the DC terminal of the bidirectional converter is connected to the DC traction contact network via a second switch. The short-circuit protection system includes a short-circuit detection circuit, a bypass drive circuit, a controller, and a bypass protection device connected in parallel with the bidirectional converter. The short-circuit detection circuit is used to perform short-circuit detection based on the current signal at the DC end of the bidirectional converter and the traction voltage signal of the DC traction contact network, and transmit the short-circuit detection result to the bypass drive circuit and the controller. When the short circuit detection result indicates that a short circuit fault has occurred, the bypass drive circuit drives the bypass protection device to operate. When the short-circuit detection result indicates a short-circuit fault, the controller controls the bidirectional converter to stop working and controls the first switch and the second switch to disconnect. The short-circuit detection circuit includes a current acquisition module, a signal isolation module, a fast short-circuit detection module, a slow short-circuit detection module, and a comprehensive short-circuit judgment module; The current acquisition module is used to acquire the current signal at the DC terminal of the bidirectional converter and convert the current signal at the DC terminal of the bidirectional converter into a first voltage signal. The signal isolation module is used to amplify and isolate the first voltage signal transmitted by the current acquisition module to obtain a second voltage signal; The short-circuit fast detection module is used to determine whether a near-end short-circuit fault has occurred based on the traction voltage signal and the second voltage signal transmitted by the signal isolation module, and to obtain a near-end short-circuit fault detection signal; The short-circuit slow detection module is used to determine whether a remote short-circuit fault has occurred based on the traction voltage signal and the second voltage signal transmitted by the signal isolation module, and to obtain a remote short-circuit fault detection signal. The short-circuit comprehensive judgment module is used to determine the short-circuit detection result based on the near-end short-circuit fault detection signal transmitted by the short-circuit fast detection module and the far-end short-circuit fault detection signal transmitted by the short-circuit slow detection module.

2. The short-circuit protection system for the bidirectional traction converter according to claim 1, characterized in that, If the second voltage signal is greater than the first voltage threshold signal and the traction voltage signal is less than the second voltage threshold signal, then a near-end short-circuit fault is determined to have occurred. If, within a preset time period, the absolute value of the change in the second voltage signal is greater than the first voltage change threshold and the absolute value of the change in the traction voltage signal is greater than the second voltage change threshold, then a remote short circuit fault is determined to have occurred. If the near-end short-circuit fault detection signal indicates a near-end short-circuit fault, or if the far-end short-circuit fault detection signal indicates a far-end short-circuit fault, then the short-circuit detection result is determined to be a short-circuit fault.

3. The short-circuit protection system for the bidirectional traction converter according to claim 1, characterized in that, The signal isolation module includes an amplification unit and an isolation unit; The input terminal of the amplification unit is connected to the input terminal of the signal isolation module, and the output terminal of the amplification unit is connected to the input terminal of the isolation unit. The output terminal of the isolation unit is connected to the output terminal of the signal isolation module; The signal isolation module receives the first voltage signal at its input terminal and outputs the second voltage signal at its output terminal.

4. The short-circuit protection system of the bidirectional traction converter according to claim 1, characterized in that, The short-circuit slow detection module includes a first voltage slow detection unit, a second voltage slow detection unit, and a first AND gate; The input terminal of the first voltage slow detection unit is connected to the first input terminal of the short-circuit slow detection module, and the output terminal of the first voltage slow detection unit is connected to the first input terminal of the first AND gate. The first voltage slow detection unit is used to detect whether the absolute value of the change in the second voltage signal is greater than the first voltage change threshold within a preset time period. The input terminal of the second voltage slow detection unit is connected to the second input terminal of the short-circuit slow detection module, and the output terminal of the second voltage slow detection unit is connected to the second input terminal of the first AND gate. The second voltage slow detection unit is used to detect whether the absolute value of the change in the traction voltage signal is greater than the second voltage change threshold within a preset time period. The output of the first AND gate is connected to the output of the short-circuit slow detection module; The first input terminal of the short-circuit slow detection module is used to input the second voltage signal, the second input terminal of the short-circuit slow detection module is used to input the traction voltage signal, and the output terminal of the short-circuit slow detection module is used to output the remote short-circuit fault detection signal.

5. The short-circuit protection system for the bidirectional traction converter according to claim 1, characterized in that, The short-circuit fast detection module includes a first voltage fast detection unit, a second voltage fast detection unit, and a fifth AND gate; The input terminal of the first voltage fast detection unit is connected to the first input terminal of the short-circuit fast detection module, and the output terminal of the first voltage fast detection unit is connected to the first input terminal of the fifth AND gate. The first voltage fast detection unit is used to detect whether the second voltage signal is greater than the first voltage threshold signal. The input terminal of the second voltage fast detection unit is connected to the second input terminal of the short-circuit fast detection module, and the output terminal of the second voltage fast detection unit is connected to the second input terminal of the fifth AND gate. The second voltage fast detection unit is used to detect whether the traction voltage signal is less than the second voltage threshold signal. The output of the fifth AND gate is connected to the output of the short-circuit fast detection module; The first input terminal of the short-circuit fast detection module is used to input the second voltage signal, the second input terminal of the short-circuit fast detection module is used to input the traction voltage signal, and the output terminal of the short-circuit fast detection module is used to output the near-end short-circuit fault detection signal.

6. The short-circuit protection system for the bidirectional traction converter according to claim 1, characterized in that, The short-circuit comprehensive judgment module includes a fourth AND gate, a second transistor, a thirty-seventh resistor, a thirty-eighth resistor, and a twentieth capacitor; The first input terminal of the fourth AND gate is used to input the near-end short-circuit fault detection signal, the first input terminal of the fourth AND gate is used to input the far-end short-circuit fault detection signal, the output terminal of the fourth AND gate is connected to the base of the second transistor through the thirty-seventh resistor, the base of the second transistor is also connected to the emitter and the second ground terminal of the second transistor through the thirty-eighth resistor and the twentyth capacitor connected in parallel, respectively, and the collector of the second transistor is used to output the short-circuit detection result.

7. The short-circuit protection system for the bidirectional traction converter according to any one of claims 1 to 6, characterized in that, The bypass drive circuit includes a square wave generator; The square wave generator is used to continuously output a square wave signal; The bypass drive circuit is used to generate a drive signal based on the square wave signal to drive the bypass protection device to work when the short circuit detection result indicates that a short circuit fault has occurred. When the short-circuit detection result indicates that no short-circuit fault has occurred, the square wave signal is blocked.

8. The short-circuit protection system for the bidirectional traction converter according to any one of claims 1 to 6, characterized in that, The bypass protection device includes a phase A controllable switch bridge arm, a phase B controllable switch bridge arm, and a phase C controllable switch bridge arm. The midpoints of the A-phase controllable switch bridge arm, the B-phase controllable switch bridge arm, and the C-phase controllable switch bridge arm are all connected to the AC terminals of the bypass protection device and the corresponding bidirectional converters. The two ends of the A-phase controllable switch bridge arm, the two ends of the B-phase controllable switch bridge arm, and the two ends of the C-phase controllable switch bridge arm are all connected to the DC terminals of the bypass protection device and the corresponding bidirectional converters.

9. A bidirectional traction converter, characterized in that, Including the short-circuit protection system of the bidirectional traction converter as described in any one of claims 1 to 8.

Images