Rectifier input power failure rapid detection method

Abstract

The invention discloses a rectifier input power failure rapid detection method comprising the following steps: virtual voltage signal construction: assuming that a mathematical model of a real input voltage is Us = Vgridsin (w0t + theta0), a rectifier is connected to a power grid, Vgrid = 220 *, a phase-locked loop can calculate w0, and a current phase theta n is calculated through integration; after the controller is powered on and the phase-locked loop stably operates for a period of time, recording a current phase theta n, then constructing a virtual voltage signal by using Us' = Vgridsin (w0t + theta n), and synchronizing the phase of Us' with Us every 10 cycles to reduce accumulated errors; inputting power failure detection: setting a proportion threshold value th; and when Us / Us'lt, th, indicating that the input voltage is powered off, and needing to block the driving pulse for protection, the input voltage can be detected at the moment of the input power failure, the response is quick, and the method is mainly applied to the field of power electronics.

Description

Technical Field

[0001] This invention relates to a rectifier for the input stage of a switching power supply, and more particularly to a method for rapid detection of input power failure in a rectifier. Background Technology

[0002] Currently, the input stage of a switching power supply typically requires AC-DC conversion, also known as rectification. The rectifier topology is as follows: Figure 1 As shown. When the input stage of the power supply uses uncontrolled rectification, although the circuit operation mode is simple, the uncontrollability of the diodes causes the input current to be non-sinusoidal, containing a large number of harmonic components. This results in a decrease in the power factor of the circuit and an unadjustable output voltage. Therefore, the rectifier is generally controlled to improve the power factor and regulate the output voltage.

[0003] like Figure 2 As shown, the classic rectifier control loop is a closed-loop output voltage-inductor current dual proportional-integral (PI) controller, with the controller consisting of a proportional element and an integral element connected in parallel. The sine wave multiplied by the outer-loop PI controller output is generated by phase-locked loop (PLL) of the input voltage. If a power supply abnormality occurs during rectifier operation, causing a sudden input power failure, both the PLL and the controller will malfunction. At this time, the large capacitor on the DC side still has voltage, potentially leading to an unpredictable circuit state and damaging the circuit hardware. Therefore, it is necessary to block the MOSFET drive pulse after detecting an input power failure to protect the circuit.

[0004] Existing technology and its limitations:

[0005] Existing input power failure detection methods rely on RMS detection, determining a power failure based on the RMS value of the input voltage falling below a set threshold. However, calculating the RMS value requires a full data cycle, resulting in a slow response time. This invention proposes a faster detection method. It constructs a virtual voltage signal similar to the input voltage using the amplitude and frequency obtained from phase-locked loop (PLL) under normal operating conditions. If the ratio of the real voltage signal to the virtual voltage signal is less than a certain threshold, a voltage drop in the real voltage signal is considered to have occurred. This method uses instantaneous values ​​for power failure detection, eliminating delay and providing a significantly faster response compared to the RMS method.

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

[0007] The purpose of this invention is to provide a method for rapid detection of rectifier input power failure, so as to solve the above-mentioned technical problems existing in the prior art.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] The rectifier input power failure rapid detection method of the present invention includes:

[0010] Step one: virtual voltage signal construction:

[0011] 1) Assuming the mathematical model of the real input voltage is Us = Vgridsin(w0t+θ0), the rectifier is connected to the grid, then Vgrid = 220* , the phase-locked loop can calculate w0, and the current phase θn is calculated by integration;

[0012] 2) After the controller is powered on and the phase-locked loop is stable for a period of time, record the current phase θn, then use Us' = Vgridsin(w0t+θn) to construct the virtual voltage signal, and synchronize the phase of Us' with Us every 10 cycles to reduce cumulative error;

[0013] Step two: input power failure detection:

[0014] 1) Set a proportional threshold th;

[0015] 2) In normal state, Us / Us'≈1, which is much larger than th; when Us / Us'<th, it means that the input voltage is powered off, and the drive pulse needs to be blocked for protection.

[0016] Compared with the prior art, the rectifier input power failure fast detection method provided by the present application can detect the input power failure at the moment of input power failure and respond quickly. It is mainly applied in the field of power electronics. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of the rectifier topology structure in the prior art;

[0018] Figure 2 is a schematic diagram of the rectifier control loop in the prior art;

[0019] Figure 3 is a schematic diagram of the power failure detection in the embodiment of the present application;

[0020] Figure 4 is the power failure detection flowchart of the embodiment of the present application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments, which do not constitute a limitation on the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0022] First, the terms that can be used in this paper are described as follows:

[0023] The terms "include", "contain", "have", "possess" or other similar semantic descriptions should be interpreted as non-exclusive inclusion.

[0024] The contents not described in detail in the embodiments of the present application belong to the prior art known to those skilled in the art. If the specific conditions are not specified in the embodiments of the present application, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used in the embodiments of the present application are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0025] The rectifier input power failure fast detection method of the present application comprises:

[0026] Step one: virtual voltage signal construction:

[0027] 1) Assuming that the mathematical model of the real input voltage is Us = Vgridsin(w0t+θ0), the rectifier is connected to the power grid, then Vgrid = 220* , the phase-locked loop can calculate w0, and the current phase θn can be calculated by integration;

[0028] 2) After the controller is powered on and the phase-locked loop is stably running for a period of time, the current phase θn is recorded, then the virtual voltage signal is constructed by using Us' = Vgridsin(w0t+θn), and the phase of Us' is synchronized with Us every 10 cycles to reduce the cumulative error;

[0029] Step two: input power failure detection:

[0030] 1) Set a proportional threshold th;

[0031] 2) In normal state, Us / Us'≈1, which is much larger than th; when Us / Us'<th, it indicates that the input voltage is powered off, and the drive pulse needs to be blocked for protection.

[0032] In the step one, 1), the phase-locked loop is a notch filter type phase-locked loop or a generalized second-order integral phase-locked loop.

[0033] In the step two, 1), the proportional threshold th is 20% to 30%.

[0034] This method is applied to the field of power electronics, which can detect the input power failure in an instant and respond quickly.

[0035] As can be seen from the above, the rectifier input power failure fast detection method of the embodiments of the present application can detect the input power failure in an instant and respond quickly. It is mainly applied to the field of power electronics.

[0036] In order to more clearly show the technical solutions provided by the present application and the technical effects produced, the present application is described in detail below with specific embodiments.

[0037] Embodiment 1

[0038] As shown in Figure 3 , Figure 4 ,

[0039] Invention point principle description:

[0040] 1) Virtual voltage signal construction:

[0041] Assuming that the mathematical model of the real input voltage is Us = Vgridsin(w0t+θ0), the rectifier is generally connected to the power grid, then Vgrid = 220* , the phase-locked loop can calculate w0, and the current phase θn can be calculated by integration. The phase-locked loop can be a notch filter type phase-locked loop, a generalized second-order integral phase-locked loop, etc., and the type is not limited.

[0042] After the controller is powered on and the phase-locked loop is stably running for a period of time, the current phase θn is recorded, then the virtual voltage signal is constructed by using Us' = Vgridsin(w0t+θn), and the phase of Us' is synchronized with Us every 10 cycles to reduce the cumulative error.

[0043] 2) Input power failure detection

[0044] A proportional threshold th is set, such as 20% or 30%. Under normal conditions, Us / Us'≈1, which is much greater than th; when Us / Us'<th, it indicates that the input voltage has failed, and the drive pulse needs to be blocked for protection.

[0045] As shown in Figure 3 , this method can detect the input power failure at the moment and respond quickly. It is applied to the field of power electronics. The overall flow chart is shown in Figure 4 .

[0046] The above is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements within the technical range disclosed by the present application can be easily thought of by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. The information disclosed in the background section of this paper is only intended to deepen the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for fast detection of input brownout in a rectifier, characterized by, The application relates to a method for detecting input voltage drop of a power supply system. Step one: virtual voltage signal construction 1) Assuming the mathematical model of the real input voltage is Us = Vgridsin(w0t+θ0), the rectifier is connected to the grid, then Vgrid = 220* , the phase-locked loop can calculate w0, and the current phase θn is calculated by integration; 2) After the controller is powered on and the phase-locked loop is stably operated for a period of time, the current phase theta n is recorded, then a virtual voltage signal is constructed by using Us'=Vgridsin(w0t+theta n), and the phase of Us' is synchronized with that of Us every 10 cycles, so as to reduce accumulated errors; Step two: input voltage drop detection 1) A proportional threshold th is set; 2) In a normal state, Us / Us' is approximately equal to 1 and is much larger than th; when Us / Us' is less than th, it is indicated that the input voltage drops, and the driving pulse needs to be blocked to be protected.

2. The rectifier input brown-out quick detection method of claim 1, wherein, In the step one, the phase-locked loop is a notch filter type phase-locked loop or a generalized second-order integral phase-locked loop.

3. The rectifier input brown-out quick detection method of claim 1, wherein, In the step two, the proportional threshold th is 20% to 30%.

4. The rectifier input brown-out quick detection method according to claim 1, 2 or 3, characterized in that, The method is applied to the field of power electronics and can detect the input voltage drop in an instant and respond quickly.

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