Protection method based on power-down spike pulse of single-phase rectifier

Abstract

The invention discloses a protection method based on a single-phase rectifier power-down spike pulse, and the method comprises the steps: installing a current sensor at a key node of a rectifier circuit, and monitoring the input current of a rectifier in real time. When it is detected that the current is increased abnormally and reaches a preset peak current threshold value, it is considered that the rectifier is in a power-down state; the DSP judges whether a current peak is caused by power failure or not according to a preset algorithm and a threshold value, a control signal is generated in time, a turn-off signal is sent to the PWM control module, a PWM switch tube is turned off in time, and current is prevented from continuously passing. And after the PWM switching tube receives the turn-off signal, the circuit is turned off immediately, a current path is cut off, and continuous generation of a current peak is prevented. And meanwhile, the rectifier enters a protection mode and waits for the power supply to return to normal. The current peak during power failure can be effectively suppressed, and circuit elements are protected.

Description

Technical Field

[0001] The invention relates to an EMI filter device in a circuit, and in particular to a protection method based on a power-off spike pulse of a single-phase rectifier. Background Art

[0002] Rectifiers are widely used in various power electronic devices to convert AC power into DC power. During normal operation, the rectifier can stably regulate the output voltage and current. However, when the rectifier suddenly loses power, the EMI filter components in the circuit (such as inductor L cm 1. L cm2 , L cm3 The presence of capacitors CX1, CX2, and CX3 may cause current spikes, which can greatly reduce the stability of the circuit output, damage circuit components, and even shorten the service life of the device.

[0003] like Figure 1 As shown, existing rectifier protection methods mostly rely on the selection of hardware protection circuits or passive components, and cannot fundamentally avoid the generation of current spikes.

[0004] In response to the current spike problem when the rectifier loses power, the existing protection measures mainly control the circuit output through the protection module in the DSP code on the control panel, or filter out high-frequency components and reduce the amplitude of the current spike through physical hardware protection such as LC filters / electrolytic capacitors, but these protection schemes do not control the PWM switch tube in time. Therefore, at the moment of power failure, the DC side potential is greater than the AC side potential, the rectifier circuit is transformed into an inverter circuit, and the current flows from right to left. Considering that there is no PWM signal control on the switch tube, the current will flow from the high-potential left side through the switch tube to the right side, oscillating with the capacitor and inductor of the AC incoming line EMI filter, causing the output waveform to oscillate.

[0005] Therefore, if Figure 2 As shown, if the switch tube is not turned off after power failure, the circuit output will be out of control.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a protection method based on power-off spike pulse of a single-phase rectifier to solve the above technical problems existing in the prior art.

[0008] The objective of the present invention is achieved through the following technical solutions:

[0009] The present invention provides a protection method based on a single-phase rectifier power-off spike pulse:

[0010] First, current sensors are installed at key nodes of the rectifier circuit to monitor the input current of the rectifier in real time. When an abnormal increase in current is detected and reaches a preset current spike threshold, the rectifier is considered to be in a power-off state.

[0011] Then, the detected current signal is input into a digital signal processor (DSP) for analysis and processing, and the digital signal processor (DSP) determines whether it is a current spike caused by power failure according to a preset algorithm and threshold value;

[0012] Afterwards, when a power-off spike pulse is detected, the digital signal processor (DSP) immediately generates a control signal and sends a shutdown signal to the PWM control module to turn off the PWM switch tube in time to prevent the current from continuing to flow.

[0013] Compared with the prior art, the protection method based on the power-off spike pulse of the single-phase rectifier provided by the present invention generates a control signal by detecting the current change at the moment of power-off, thereby turning off the PWM switch tube, which can effectively suppress the current spike during power-off and protect circuit components. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a single-phase rectifier circuit structure with an EMI filter in the prior art;

[0015] Figure 2 The output waveform of the power circuit that oscillates after power failure in the prior art;

[0016] Figure 3 This is a flow chart of power-off protection according to an embodiment of the present invention;

[0017] Figure 4 The PWM control signal waveform after adding power-off protection in the embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0019] First, the terms that may be used in this article are explained as follows:

[0020] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0021] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0022] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0023] The contents not described in detail in the examples of the present invention belong to the prior art known to professionals in the field. If no specific conditions are specified in the examples of the present invention, the conditions are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used in the examples of the present invention, they are all conventional products that can be purchased commercially.

[0024] The present invention provides a protection method based on a single-phase rectifier power-off spike pulse:

[0025] First, current sensors are installed at key nodes of the rectifier circuit to monitor the input current of the rectifier in real time. When an abnormal increase in current is detected and reaches a preset current spike threshold, the rectifier is considered to be in a power-off state.

[0026] Then, the detected current signal is input into a digital signal processor (DSP) for analysis and processing, and the digital signal processor (DSP) determines whether it is a current spike caused by power failure according to a preset algorithm and threshold value;

[0027] Afterwards, when a power-off spike pulse is detected, the digital signal processor (DSP) immediately generates a control signal and sends a shutdown signal to the PWM control module to turn off the PWM switch tube in time to prevent the current from continuing to flow.

[0028] After receiving the shutdown signal, the PWM switch tube immediately turns off the circuit, cuts off the current path, and prevents the continuous generation of current spikes;

[0029] At the same time, the rectifier enters protection mode and waits for the power supply to return to normal. When the power supply is restored, the digital signal processor (DSP) detects normal input voltage and current conditions, releases the protection state, restarts the PWM control module, and restores the rectifier to normal operation.

[0030] The digital signal processor (DSP) program also performs algorithm optimization according to the load characteristics and working environment of the rectifier, and the current peak threshold mentioned is also set according to the specific application environment.

[0031] In summary, the protection method based on the power-off spike pulse of the single-phase rectifier in the embodiment of the present invention generates a control signal by detecting the current change at the moment of power-off, thereby turning off the PWM switch tube, effectively suppressing the current spike during power-off and protecting the circuit components.

[0032] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the embodiments of the present invention are described in detail with specific embodiments below.

[0033] Example 1

[0034] like Figure 3 As shown:

[0035] First, current sensors are installed at key nodes of the rectifier circuit to monitor the input current of the rectifier in real time. When an abnormal increase in current is detected and reaches the preset peak current threshold, the rectifier is considered to be in a power-off state;

[0036] Next, the detected current signal is input into a digital signal processor (DSP) for analysis and processing. The DSP determines whether it is a current spike caused by power failure based on a preset algorithm and threshold value.

[0037] When a power-off spike pulse is detected, the DSP immediately generates a control signal and sends a shutdown signal to the PWM control module to shut down the PWM switch tube in time to prevent the current from continuing to flow. After receiving the shutdown signal, the PWM switch tube immediately shuts down the circuit, cuts off the current path, and prevents the continuous generation of current spikes. At the same time, the rectifier enters the protection mode and waits for the power supply to return to normal. When the power supply is restored, the DSP detects the normal input voltage and current conditions, releases the protection state, restarts the PWM control module, and restores the rectifier to normal operation.

[0038] It should be noted that the DSP program described above also needs to be optimized according to the load characteristics and working environment of the rectifier, and the current spike threshold mentioned should also be set according to the specific application environment.

[0039] Testing and experimental verification:

[0040] The solution proposed by the present invention is simulated. Figure 4 As shown:

[0041] First, the current sensor is installed at the input end of the rectifier to detect the transient changes of the input current; at the same time, a high-speed, high-precision DSP is selected to quickly process the input signal and generate control instructions in time; and the PWM control module is connected to the DSP to receive the shutdown signal of the DSP.

[0042] A dedicated algorithm is written inside the DSP, which mainly includes a spike pulse detection module, a signal processing module, and a control signal generation module. The spike pulse detection module is responsible for monitoring current changes. When the current exceeds the preset threshold, the signal processing module is triggered. The signal processing module determines whether it is a power-off spike based on a specific algorithm and generates a corresponding control signal. The control signal generation module sends a shutdown signal to the PWM control module based on the processing result.

[0043] In addition, the current spike threshold is set according to the specific application environment to avoid false operation and ensure sufficient protection. At the same time, the algorithm inside the DSP needs to consider the load characteristics and working environment of the rectifier to ensure the accuracy and reliability of the judgment.

[0044] The simulation experiment results show that the present invention can effectively avoid the generation of current spikes by quickly turning off the PWM switch tube when the rectifier loses power, thereby protecting circuit components from damage caused by instantaneous overcurrent. Compared with the traditional passive protection method, the active control-based protection mechanism of the present invention has a faster response speed and better protection effect. It is particularly suitable for high-performance and high-reliability power electronic equipment.

[0045] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A protection method based on power-off spike pulse of single-phase rectifier, characterized by: First, current sensors are installed at key nodes of the rectifier circuit to monitor the input current of the rectifier in real time. When an abnormal increase in current is detected and reaches a preset current spike threshold, the rectifier is considered to be in a power-off state. Then, the detected current signal is input into a digital signal processor (DSP) for analysis and processing, and the digital signal processor (DSP) determines whether it is a current spike caused by power failure according to a preset algorithm and threshold value; Afterwards, when a power-off spike pulse is detected, the digital signal processor (DSP) immediately generates a control signal and sends a shutdown signal to the PWM control module to turn off the PWM switch tube in time to prevent the current from continuing to flow.

2. The protection method based on power-off spike pulse of single-phase rectifier according to claim 1 is characterized in that: After receiving the shutdown signal, the PWM switch tube immediately turns off the circuit, cuts off the current path, and prevents the continuous generation of current spikes; At the same time, the rectifier enters protection mode and waits for the power supply to return to normal. When the power supply is restored, the digital signal processor (DSP) detects normal input voltage and current conditions, releases the protection state, restarts the PWM control module, and restores the rectifier to normal operation.

3. The protection method based on power-off spike pulse of single-phase rectifier according to claim 2 is characterized in that: The digital signal processor (DSP) program also performs algorithm optimization according to the load characteristics and working environment of the rectifier, and the current peak threshold mentioned is also set according to the specific application environment.

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