Real-time monitoring device for large-current rectifier bridge arm

Abstract

A real-time monitoring device for a large-current rectifier bridge arm comprises a rectifier bridge circuit, the rectifier bridge circuit comprises a plurality of rectifier bridge arms, each rectifier bridge arm is provided with a current transformer used for detecting the current of the bridge arm, the current transformer is sleeved on each rectifier bridge arm, and whether a system works normally or not is judged by detecting the current of the bridge arm. The real-time monitoring device for the large-current rectifier bridge arm is not directly connected with a rectifier loop, a signal conversion circuit and a waveform arrangement circuit are designed to limit current signals and enhance the display effect, and in addition, when a fault occurs, a dry contact outputs an alarm for starting a rectifier bridge protection function.

Description

Technical Field

[0001] The utility model relates to the technical field of rectifier bridge fault monitoring, in particular to a high-current rectifier bridge arm real-time monitoring device. Background Art

[0002] In high-power rectifier power supplies, a 6-pulse thyristor rectifier bridge is usually used to achieve the conversion of AC to DC. However, during the operation of the rectifier bridge, the rectifier components may be damaged due to overvoltage, overcurrent, etc., resulting in a bridge arm short circuit. Alternatively, the trigger pulse may not be triggered and the fast fuse may blow, resulting in a bridge arm open circuit.

[0003] When a bridge arm fails, the rectifier bridge cannot operate normally, generating large currents or drastic changes in DC output voltage, which can damage the rectifier bridge itself or other equipment, endangering personal and equipment safety. Therefore, when a rectifier bridge arm fails, it is necessary to promptly detect and activate the protective device.

[0004] In order to shorten the maintenance time when a fault occurs and quickly locate the faulty bridge arm, the specific location of the fault must be determined when the rectifier bridge arm fails, which is convenient for maintenance and replacement, thereby improving equipment utilization.

[0005] In practical applications, most monitoring components require direct connection to the rectifier circuit, which can easily affect the operation of the rectifier bridge itself. Non-contact monitoring components often use CT to monitor the bridge arm current. Changes in output current can affect the component's monitoring effectiveness, and an open circuit can generate overvoltage, causing component damage and even affecting the operation of the rectifier bridge.

[0006] A Chinese patent document discloses a "method, system and medium for detecting thyristor faults in a rectifier of an excitation system" (CN202311214623). This invention patent uses the three-phase current amplitude of the input rectifier to calculate the effective value passing through the rectifier at a specific trigger angle and compares it with the effective value of the actual rectified output current to determine whether the rectifier bridge has deterioration or fault problems.

[0007] This patent provides a method, system, and medium for detecting thyristor faults in a rectifier of an excitation system. The method, system, and medium compare the difference between the theoretical and actual output current RMS values ​​to determine the status of the rectifier bridge. This method fails to locate the faulty bridge arm, and once a fault occurs, the rectifier bridge must be shut down, hindering troubleshooting. Furthermore, the system lacks an external rectifier status display for maintenance personnel to view, making it difficult to locate the cause of the fault after a power outage and cabinet removal. Furthermore, the basis for determining rectifier faults relies solely on the setting of the current RMS difference coefficient threshold, which can lead to misjudgment under strong electromagnetic interference. Summary of the Invention

[0008] The technical problem to be solved by the utility model is to provide a large current rectifier bridge arm real-time monitoring device, which adopts CT mutual inductor to monitor the bridge arm current and the corresponding signal processing flow to solve the problems in the prior art that contact monitoring affects the operation of the rectifier bridge, and non-contact monitoring is prone to failure and has poor display effect.

[0009] In order to solve the above technical problems, the technical solution adopted by the utility model is: a large current rectifier bridge arm real-time monitoring device, including a rectifier bridge circuit, the rectifier bridge circuit includes multiple rectifier bridge arms, and each rectifier bridge arm is provided with a current transformer for detecting the bridge arm current. The current transformer is mounted on each rectifier bridge arm, and the system is judged whether it is working normally by detecting the bridge arm current.

[0010] Preferably, the current transformer is electrically connected to the signal conversion circuit and the waveform conditioning circuit in sequence.

[0011] Preferably, the waveform conditioning circuit is electrically connected to the waveform latch circuit, the display driving circuit and the display device in sequence.

[0012] Preferably, the signal conversion circuit adjusts the output current of the current transformer through a diode rectifier bridge, and converts the current waveform into a voltage waveform that is convenient for subsequent processing.

[0013] The utility model provides a high current rectifier bridge arm real-time monitoring device, which has the following beneficial effects:

[0014] (1) There is no direct connection with the rectifier main circuit and it does not affect the operation of the main circuit;

[0015] (2) It limits the current level of the detection CT, avoids overvoltage when the CT is disconnected, and improves the stability and safety of the monitoring device;

[0016] (3) The CT current signal is converted into a voltage signal and the display is enhanced by using a waveform sorting circuit and a latch circuit, thereby improving the readability of the monitoring device;

[0017] (4) Provide dry contact output alarm when rectifier bridge fails, which can be used for remote alarm display or trigger rectifier bridge protection action;

[0018] (5) The faulty bridge arm can be located, which is convenient for maintenance or replacement, thus improving maintenance efficiency and equipment utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0020] Figure 1 This is the main circuit diagram of the rectifier bridge current detection of the utility model;

[0021] Figure 2This is the structural block diagram of the control system of the utility model;

[0022] Figure 3 This is a schematic diagram of the signal conversion circuit of the present utility model;

[0023] Figure 4 This is the schematic diagram of the waveform arrangement circuit of the utility model;

[0024] Figure 5 This is the principle diagram of the waveform latch circuit of the utility model;

[0025] Figure 6 This is a schematic diagram of the display drive circuit of the utility model. DETAILED DESCRIPTION

[0026] like Figure 1-2 As shown, a large current rectifier bridge arm real-time monitoring device includes a rectifier bridge circuit, which includes multiple rectifier bridge arms 1. A current transformer 2 for detecting the bridge arm current is provided on each rectifier bridge arm 1. The current transformer 2 is mounted on each rectifier bridge arm 1, and determines whether the system is working normally by detecting the bridge arm current.

[0027] Preferably, the current transformer 2 is electrically connected to the signal conversion circuit and the waveform conditioning circuit in sequence.

[0028] Preferably, the waveform conditioning circuit is electrically connected to the waveform latch circuit, the display driving circuit and the display device in sequence.

[0029] Preferably, the signal conversion circuit adjusts the output current of the current transformer through a diode rectifier bridge, and converts the current waveform into a voltage waveform that is convenient for subsequent processing.

[0030] According to the characteristics of the input signal, the output current of the current transformer is rectified through a diode rectifier bridge, and the current waveform is converted into a voltage waveform that is convenient for the subsequent stage to process. The relevant circuit is as follows Figure 3 This circuit converts the current output by the CT into a voltage-type square wave signal with a better waveform for use in the following circuits.

[0031] because Figure 3 The high level of the output waveform is the tube voltage drop of the diode, the voltage is low, and the current is not constant at the high level. In order to facilitate the use of the subsequent circuit, Figure 4 The circuit pair Figure 3 The output waveform is sorted and finally forms a standard square wave signal for subsequent work.

[0032] Since each bridge arm of the three-phase fully controlled rectifier circuit only works for 1 / 3 of a cycle during operation, the detected current waveform will fluctuate, causing the display light on the display panel to flicker. However, due to the high frequency, although it is not easy for the human eye to detect, it will affect the brightness of the display light. In order to better solve this problem, it is necessary to properly latch the signal within the power frequency cycle time. That is, as long as the current is detected within the cycle time, it will continue to display until the next power frequency cycle detects that the current becomes smaller, then the latched signal will change immediately, and so on. The related latch circuit is as follows: Figure 5 shown.

[0033] The latched signal can be used for signal display, but since the driving capability of the latched signal is limited, additional driving is required during signal display. The driving circuit is as follows: Figure 6 .

[0034] This patent provides a real-time monitoring device for a large current rectifier bridge arm, which has no direct connection to the rectifier circuit, and is designed with signal conversion and waveform sorting circuits to limit the current signal and enhance the display effect. In addition, when a fault occurs, a dry contact output alarm is provided to activate the rectifier bridge protection function.

[0035] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be the technical solutions set forth in the claims, including equivalent alternatives to the technical features of the technical solutions set forth in the claims. Equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A high current rectifier bridge arm real-time monitoring device, comprising a rectifier bridge circuit, wherein the rectifier bridge circuit comprises a plurality of rectifier bridge arms (1), characterized in that: A current transformer (2) for detecting the bridge arm current is provided on each rectifier bridge arm (1). The current transformer (2) is sleeved on each rectifier bridge arm (1) and determines whether the system is operating normally by detecting the bridge arm current.

2. The high current rectifier bridge arm real-time monitoring device according to claim 1, characterized in that: The current transformer (2) is electrically connected to the signal conversion circuit and the waveform adjustment circuit in sequence.

3. The high current rectifier bridge arm real-time monitoring device according to claim 2, characterized in that: The waveform conditioning circuit is then electrically connected to the waveform latch circuit, the display driving circuit and the display device in sequence.

4. The high current rectifier bridge arm real-time monitoring device according to claim 2, characterized in that: The signal conversion circuit adjusts the output current of the current transformer through a diode rectifier bridge, and at the same time converts the current waveform into a voltage waveform that is convenient for subsequent processing.

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