Cycle frequency converter thyristor fault-tolerant control method and system based on redundant bridge arm

Abstract

The invention provides a cycle frequency converter fault-tolerant control method and system based on redundant bridge arms, and belongs to the technical field of frequency converter fault-tolerant control. The device comprises an AC-AC frequency conversion circuit formed by three N-phase input-single-phase output frequency conversion circuits, a j-phase unit comprises N normal working bridge arms, a redundant bridge arm and N bidirectional controllable normally-open switches, and each bidirectional controllable normally-open switch connects the midpoint o of the redundant bridge arm to the midpoints of the other N bridge arms; when a rear open-circuit fault occurs in the thyristor, the corresponding switch is closed, a trigger signal on the thyristor is transferred to the corresponding redundant thyristor, and the redundant thyristor is used for replacing the fault thyristor to conduct the circuit, so that smooth redundant switching of the frequency converter is realized, zero clearance and accuracy of redundant switching are realized, and the reliability of the frequency converter is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronic conversion, and in particular is a fault-tolerant control method for thyristor faults of a cycloconverter based on redundant bridge arms. Background Art

[0002] The cycloconverter is an important power electronic conversion device, with its technological background dating back to the rise of power electronics in the mid-20th century. With the growing demand for AC motor speed regulation in the industrial sector, traditional mechanical speed regulation and DC drive solutions have gradually exposed limitations such as low efficiency and complex maintenance. Frequency conversion technology based on semiconductor devices has become a research hotspot. Against this backdrop, the cycloconverter, a typical representative of direct AC-AC frequency conversion technology, emerged. It directly converts input power-frequency AC power to variable low-frequency AC power through thyristor phase control, eliminating the intermediate DC link and demonstrating unique advantages in the field of high-power, low-speed transmission.

[0003] Fault-tolerant control technology for frequency converters is an important research area that has developed in response to the demand for high-reliability power electronics systems. With the widespread application of frequency converters in key areas such as industrial transmission, rail transportation, and new energy, operational reliability issues are becoming increasingly prominent. Traditional frequency converters typically use thyristors as power switching devices. Factors such as device aging, overload, and grid disturbances can cause switch failures, leading to system downtime and even equipment damage. This risk is unacceptable in continuous production industrial environments or safety-critical transportation applications, prompting research on fault-tolerant control technology for frequency converters. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a fault-tolerant control method for a frequency converter. When a single thyristor or two specific thyristors fail, the faulty thyristor can be quickly replaced by a redundant bridge arm thyristor, thereby avoiding distortion of the inverter output voltage and affecting system performance, and realizing thyristor fault protection.

[0005] The present invention solves the above technical problems by adopting the following technical solutions:

[0006] The present invention first proposes a frequency converter with fault tolerance, comprising three phase units A, B, and C. Each phase unit comprises N bridge arms in normal operation, each bridge arm comprising two anti-parallel thyristors, the upper and lower ends of each bridge arm being short-circuited respectively and then connected together to an output port.

[0007] The frequency converter with fault tolerance function also includes a redundant bridge arm, which has the same structure as the other N bridge arms and is composed of two anti-parallel thyristors. In addition, the frequency converter also includes N bidirectional controllable normally open switches;

[0008] Furthermore, the redundant bridge arm and the switch are connected as follows: the upper and lower ends of the redundant bridge arm are short-circuited with the upper and lower ends of the other bridge arms respectively, one end of the bidirectional controllable normally open switch is connected to the midpoint o of the redundant bridge arm, and the other end is connected to the midpoints of the other bridge arms respectively.

[0009] In addition, the present invention provides a cycloconverter fault-tolerant control method, including a normal operation control method, a single thyristor fault-tolerant control method, and a two thyristor fault-tolerant control method.

[0010] Furthermore, the control method is specifically as follows:

[0011] Before a thyristor open-circuit fault is detected, all N bidirectional controllable normally open switches are in the disconnected state, and all bridge arms are put into normal operation. A carrier waveform is generated according to the input side voltage, and a modulation wave is generated according to the output side current and speed. The cosine intercept method is used to generate the trigger signal required for normal operation of the thyristor.

[0012] Single thyristor fault tolerance control: When an open circuit fault is detected in a thyristor, the bidirectional controllable switch corresponding to the faulty thyristor is closed, and the trigger signal of the faulty thyristor is distributed to the corresponding thyristor in the redundant bridge arm;

[0013] Fault-tolerant control of dual thyristors in the same bridge arm: When two thyristors in the same bridge arm are detected to have open circuit faults at the same time, the corresponding bidirectional controllable switches are closed to distribute the trigger signals of the two faulty thyristors to the two thyristors in the redundant bridge arm respectively.

[0014] Secondly, the present invention also proposes an electronic system, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method steps of the present invention.

[0015] Finally, the present invention also provides a computer-readable storage medium storing computer instructions, wherein the computer instructions are used to enable the computer to execute the method steps of the present invention.

[0016] By adopting the above technical solution, compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0017] The present invention is based on the existing cycloconverter, has a simple structure and is easy to implement. When a single thyristor fails, or two thyristors in the same bridge arm fail at the same time, a redundant thyristor can replace the failed thyristor to ensure that the load can operate stably without being affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0019] Figure 1 The present invention is a circuit diagram of a cycloconverter based on redundant bridge arms.

[0020] Figure 2 It is a control block diagram of the frequency converter of the present invention.

[0021] Figure 3 This is a flow chart of the operation of the forward and reverse thyristors of the A-phase unit of the present invention failing in sequence.

[0022] Figure 4 This is a signal transfer diagram of the forward and reverse thyristors of the A-phase unit of the present invention being triggered in sequence. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0024] Example 1:

[0025] First reference Figure 1 As shown, the frequency converter with fault tolerance function provided by the present invention includes three phase units A, B, and C. Taking each phase unit as an example, the j phase unit includes three bridge arms 1, 2, and 3 during normal operation, j = A, B, C, and each bridge arm includes two anti-parallel thyristors T 1j / T 4j 、T 3j / T 6j 、T 5j / T 2j , the upper and lower ends of each bridge arm are short-circuited respectively, and then connected to the output port together;

[0026] The fault-tolerant frequency converter further comprises a redundant bridge arm, the structure of which is the same as that of bridge arms 1, 2 and 3, and is composed of two anti-parallel thyristors T r1j / T r2j In addition, the inverter also contains three bidirectional controllable normally open switches S 1j 、S 2j 、S 3j ;

[0027] The redundant bridge arm is connected to the switch in the following manner: the upper and lower ends of the redundant bridge arm are short-circuited with the upper and lower ends of the other bridge arms respectively, and the bidirectional controllable normally open switch S 1j 、S 2j 、S 3j One end is connected to the midpoint o of the redundant bridge arm, and the other end is connected to the midpoints u, v, and w of the other bridge arms respectively.

[0028] refer to Figure 2 As shown in the control block diagram of the frequency converter of the present invention, the specific embodiment steps are as follows:

[0029] Step 1: Real-time monitoring of the input voltage u of the frequency converter a 、u b 、u c , the input voltage phase angle θ is obtained according to the phase-locked loop, and the carrier waveforms W1, W2, and W3 of the thyristor are generated.

[0030] Implement monitoring of motor speed n, inverter output current i ma 、i mb 、i mc , based on the speed and current double closed loop control, the modulation wave y of the thyristor is generated ref_ma 、y ref_mb 、y ref_mc .

[0031] Generate thyristor trigger signal s according to thyristor carrier and modulation wave 1_j ~s 6_j , used to drive the thyristors of the inverter.

[0032] Step 2: When no thyristor open circuit fault is detected, three bidirectional controllable normally open switches S 1j 、S 2j 、S 3j Keep open, trigger signal s 1_j ~s 6_j Assigned to T 1j ~T 6j .

[0033] Step 3: When a thyristor such as T is detected 1j When the circuit breaker fails, close the bidirectional controllable normally open switch S 1j , T 1j The trigger signal s 1_j Assigned to T r1j , use T r1j Replace T 1j , the system can continue to operate stably.

[0034] Step 4: In a single thyristor such as T 1j Based on the open circuit fault, if another thyristor such as T4j Thyristor open circuit failure also occurs, then T 4j The trigger signal s 4_j Assigned to T r2j On, use T r2j Instead of T 4j , the system can continue to operate stably.

[0035] It should be noted that, in the present invention, such as T 1j and T 4j The relational terms are used for example only and are not fault tolerant measures that will only work when both thyristors fail.

[0036] refer to Figure 3 As shown in the figure, the operation process of the forward and reverse thyristors of the A phase unit of the present invention are as follows:

[0037] Step 1: The fault detection device detects the thyristor status of the frequency converter in real time. When no thyristor fault is detected, no other operations are performed, the frequency converter operates normally, and the fault detection device continues to detect; when a thyristor fault is detected, the fault location device locates the specific faulty thyristor.

[0038] Step 2: When the faulty thyristor is located as the forward thyristor T1 on the bridge arm 1 of the phase A unit, the bidirectional controlled normally open switch S1 is closed, and the other bidirectional controlled normally open switches remain in the open state. The T1 trigger signal s1 is transferred to the redundant bridge arm forward thyristor T r1 When the bridge arm reverse thyristor T4 fault is detected, the T4 trigger signal s4 is transferred to the redundant bridge arm reverse thyristor T r2 superior.

[0039] Step 3: When the faulty thyristor is located as the forward thyristor T3 on the bridge arm 2 of the phase A unit, the bidirectional controlled normally open switch S1 is closed, and the other bidirectional controlled normally open switches remain in the open state. The T3 trigger signal s3 is transferred to the redundant bridge arm forward thyristor T r1 When the bridge arm reverse thyristor T6 fault is detected, the T6 trigger signal s6 is transferred to the redundant bridge arm reverse thyristor T r2 superior.

[0040] Step 4: When the faulty thyristor is located as the forward thyristor T5 on the bridge arm 3 of the phase A unit, the bidirectional controlled normally open switch S1 is closed, and the other bidirectional controlled normally open switches remain in the open state. The T5 trigger signal s5 is transferred to the redundant bridge arm forward thyristor T r1 When the bridge arm reverse thyristor T2 fault is detected, the T2 trigger signal s2 is transferred to the redundant bridge arm reverse thyristor T r2 superior.

[0041] like Figure 4The figure shows the signal transfer diagram of the forward and reverse thyristors of the A-phase unit of the present invention.

[0042] Step 1: During normal operation, the A-phase trigger signals s1 to s6 are used to trigger the turn-on thyristors T1 to T6 respectively.

[0043] Step 2: When an open circuit fault is detected in thyristor T1, the trigger signal of T1 thyristor is transferred to T r1 The rest of the trigger signals are the same as step 1.

[0044] Step 3: Based on step 2, when an open circuit fault is detected in thyristor T4, the trigger signal of T4 thyristor is transferred to T r2 The rest of the trigger signals are the same as step 2.

[0045] Example 2:

[0046] First reference Figure 1 As shown, the frequency converter with fault tolerance function provided by the present invention includes three phase units A, B, and C. Taking each phase unit including four bridge arms as an example, the j-phase unit includes four bridge arms 1, 2, 3, and 4 during normal operation, j = A, B, C, and each bridge arm includes two anti-parallel thyristors T1j / T4j, T3j / T6j, T5j / T8j, and T7j / T2j. The upper and lower ends of each bridge arm are short-circuited respectively and then connected to the output port together;

[0047] The frequency converter with fault tolerance function also includes a redundant bridge arm, which has the same structure as bridge arms 1, 2, 3, and 4 and is composed of two anti-parallel thyristors Tr1j / Tr2j. In addition, the frequency converter also includes three bidirectional controllable normally open switches S1j, S2j, S3j, and S4j;

[0048] The redundant bridge arm and the switch are connected as follows: the upper and lower ends of the redundant bridge arm are short-circuited with the upper and lower ends of the other bridge arms respectively, and one end of the bidirectional controllable normally open switches S1j, S2j, S3j, and S4j is connected to the midpoint o of the redundant bridge arm, and the other end is connected to the midpoints u, v, w, and x of the other bridge arms respectively.

[0049] refer to Figure 2 As shown in the control block diagram of the frequency converter of the present invention, the specific embodiment steps are as follows:

[0050] Step 1: Real-time monitoring of the input voltage u of the frequency converter a 、u b 、u c 、u d , according to the phase-locked loop, the input voltage phase angle θ is obtained to generate the thyristor carrier waveforms W1, W2, W3, and W4.

[0051] Implement monitoring of motor speed n, inverter output current i ma 、i mb 、i mc , based on the speed and current double closed loop control, the modulation wave y of the thyristor is generated ref_ma 、y ref_mb 、y ref_mc .

[0052] Generate thyristor trigger signal s according to thyristor carrier and modulation wave 1_j ~s 8_j , used to drive the thyristors of the inverter.

[0053] Step 2: When no thyristor open circuit fault is detected, three bidirectional controllable normally open switches S 1j 、S 2j 、S 3j , S4j remains open, triggering signal s 1_j ~s 8_j Assigned to T 1j ~T 8j .

[0054] Step 3: When a thyristor such as T is detected 1j When the circuit breaker fails, close the bidirectional controllable normally open switch S 1j , T 1j The trigger signal s 1_j Assigned to T r1j , use T r1j Replace T 1j , the system can continue to operate stably.

[0055] Step 4: In a single thyristor such as T 1j Based on the open circuit fault, if another thyristor such as T 4j Thyristor open circuit failure also occurs, then T 4j The trigger signal s 4_j Assigned to T r2j On, use T r2j Instead of T 4j , the system can continue to operate stably.

[0056] Example 3:

[0057] This embodiment proposes an electronic system, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method steps described in the present invention.

[0058] Example 4:

[0059] This embodiment provides a computer-readable storage medium storing computer instructions, wherein the computer instructions are used to enable the computer to execute the method steps described in the present invention.

[0060] It should be noted that the processing flow of Examples 3 to 4 corresponds to the specific steps of the method provided in the embodiment of the present invention, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not fully described in this embodiment, please refer to the method provided in the embodiment of the present invention.

[0061] The program code for implementing the methods of the present application can be written in any combination of one or more programming languages. Such program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the program code is executed by the processor or controller, the functions / operations specified in the flow charts and / or block diagrams are implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0062] In the context of the present application, a machine-readable medium can be a tangible medium that can contain or store a program for use by an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared or semiconductor system, device or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium can include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0063] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0064] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A frequency converter based on redundant bridge arms, characterized in that: include: There are three phase units A, B, and C. Each phase unit includes N bridge arms. Each bridge arm includes two thyristors connected in reverse parallel. The upper and lower ends of each bridge arm are short-circuited and then connected to the output port. A redundant bridge arm, having the same structure as the N bridge arms, and an upper end and a lower end of the redundant bridge arm are short-circuited with the upper end and the lower end of the N bridge arms respectively; N bidirectional controllable switches, one end of each bidirectional controllable switch is connected to the midpoint of the redundant bridge arm, and the other end is connected to the midpoints of the N bridge arms respectively; The thyristor of the redundant bridge arm replaces the thyristor of the faulty bridge arm by closing and opening the bidirectional controllable switch to achieve fault-tolerant control.

2. The frequency converter according to claim 1, characterized in that: The bidirectional controllable switch is a bidirectional thyristor or is composed of two reverse-parallel IGBTs.

3. The frequency converter according to claim 1, characterized in that: The number N of bridge arms included in each phase unit is equal to 3.

4. The frequency converter according to claim 1, characterized in that: The number N of bidirectional controllable switches is equal to 3.

5. A fault-tolerant control method based on the frequency converter according to claim 1, characterized in that: The following steps are involved: S1. Normal operation control: When no thyristor open circuit fault is detected, all bidirectional controllable switches are kept in the off state, and the thyristors of each bridge arm are controlled to generate trigger signals according to the carrier signal and the modulation wave; S2. Single thyristor fault tolerance control: When an open circuit fault is detected in a thyristor, the bidirectional controllable switch corresponding to the faulty thyristor is closed, and the trigger signal of the faulty thyristor is distributed to the corresponding thyristor in the redundant bridge arm; S3. Fault-tolerant control of dual thyristors in the same bridge arm: When two thyristors in the same bridge arm are detected to have open circuit faults at the same time, the corresponding bidirectional controllable switches are closed to distribute the trigger signals of the two faulty thyristors to the two thyristors in the redundant bridge arm respectively.

6. The fault-tolerant control method according to claim 5, characterized in that: The carrier signal is generated according to the input side voltage, and the modulation wave is generated according to the output side current and the rotation speed.

7. An electronic system comprising: at least one processor; A memory communicatively connected to the at least one processor; characterized in that the memory stores executable instructions, and when the instructions are executed by the processor, the fault-tolerant control method described in any one of claims 5 or 6 is implemented.

8. A computer-readable storage medium storing computer instructions, characterized in that: When the instruction is executed by the processor, the fault-tolerant control method described in any one of claims 5 or 6 is implemented.

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