A power supply circuit for industrial frequency asymmetric positive and negative voltages

Abstract

The present application provides a power supply circuit for power frequency asymmetric positive and negative voltages, which controls the waveform of the power frequency asymmetric positive and negative voltages by controlling the on-off mode and time of power semiconductor, with low energy consumption, high production efficiency, and an increase in the thickness of the ceramic film. The power supply circuit for power frequency asymmetric positive and negative voltages includes loop a, loop b, and loop c. Loop a, loop b, and loop c are connected in series. Loop a, loop b, and loop c each include a switch S0, a thyristor SCR1, a thyristor SCR2, an electroplating tank E, and an electroplating tank F. By controlling the on-off mode and time of the thyristor SCR1 and the thyristor SCR2, the waveform of the power frequency asymmetric positive and negative voltages is controlled. The switch S0 remains closed. In the time period of 0-t1, both the thyristor SCR1 and the thyristor SCR2 are off. In the time period of t1-t2, the thyristor SCR1 is on and the thyristor SCR2 remains off. In the time period of t2-t3, both the thyristor SCR1 and the thyristor SCR2 are off. In the time period of t3-t4, the thyristor SCR1 is off and the thyristor SCR2 is on, completing one waveform cycle, and this cycle repeats.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectrochemical oxidation. Specifically, the present invention relates to a power supply circuit with asymmetric positive and negative power frequencies and voltages. Background Art

[0002] Thermoelectrochemical oxidation is a new surface treatment technology that has developed rapidly in recent years at home and abroad. It is developed on the basis of anodic oxidation and is also known as microplasma oxidation, plasma thermoelectrochemical oxidation, plasma-enhanced electrochemical surface ceramicization, etc. Thermoelectrochemical oxidation uses a relatively high working voltage, introducing the working region of the voltage from the Faraday region of the ordinary anodic oxidation method to the high-voltage discharge region. By enhancing and activating with arc discharge, the reaction occurring on the anode causes corona, glow, micro-arc discharge, and even spark spots on the workpiece surface at a certain current density, and a dense ceramic film is formed in-situ on the surface of the valve metal, thereby achieving surface modification and strengthening of the workpiece. Valve metals are metals that have an electrolytic valve effect in the metal-oxide-electrolyte system. Valve metals mainly include six metals, namely Al, Ti, Mg, Zr, Nb, Ta, and their alloys. This ceramic film is metallurgically bonded to the substrate, with good bonding strength and high hardness, and has excellent wear resistance, corrosion resistance, high-voltage insulation, and high-temperature shock resistance, etc., which can increase the service life of the workpiece by several times or even dozens of times.

[0003] Due to the use of high-voltage discharge in thermoelectrochemical oxidation, intense spark discharge reactions occur on the workpiece surface. The spark discharge is too intense and difficult to control, which has an important impact on the effect and density of the ceramic film in the thermoelectrochemical oxidation process. In addition, the energy consumption of high-voltage discharge is large, which is also an important factor restricting the practical application and promotion of thermoelectrochemical oxidation. The existing DC power supply equipment for thermoelectrochemical oxidation has high energy consumption, low production efficiency, and affects the thickness of the ceramic film and the electrophoretic sealing layer.

[0004] In view of this, the present invention provides a power supply circuit with asymmetric positive and negative power frequencies and voltages, which has low energy consumption, high production efficiency, and an increased thickness of the ceramic film in thermoelectrochemical oxidation. Summary of the Invention

[0005] The purpose of the present invention is to provide a power supply circuit with asymmetric positive and negative power frequencies and voltages, which controls the waveform of the asymmetric positive and negative power frequencies and voltages by controlling the on-off mode and time of power semiconductors, and has low energy consumption, high production efficiency, and an increased thickness of the ceramic film in thermoelectrochemical oxidation.

[0006] A power supply circuit for industrial frequency asymmetric positive and negative voltages, including loop a, loop b, and loop c. Loop a, loop b, and loop c are connected in series. Loop a, loop b, and loop c each include a switch S0, a thyristor SCR1, a thyristor SCR2, an electroplating tank E, and an electroplating tank F. By controlling the on-off mode and time of the thyristor SCR1 and the thyristor SCR2, the waveform of the industrial frequency asymmetric positive and negative voltages is controlled. The switch S0 remains closed. In the period from 0 to t1, both the thyristor SCR1 and the thyristor SCR2 are off. In the period from t1 to t2, the thyristor SCR1 is on and the thyristor SCR2 remains off. In the period from t2 to t3, both the thyristor SCR1 and the thyristor SCR2 are off. In the period from t3 to t4, the thyristor SCR1 is off and the thyristor SCR2 is on, completing one waveform cycle, and cycling in this way.

[0007] In some embodiments, when the lower part of the electroplating tank is positive and the upper part is negative, when the input voltage is in the positive half-cycle, since the voltage on the thyristor SCR2 is always in the reverse direction and cannot conduct, the thyristor SCR2 is equivalent to an open circuit (the equivalent circuit is as Figure 3 shown).

[0008] Furthermore, in the period from 0 to t1, the thyristor SCR1 is in the cut-off state, and the current flows from the negative end of the electroplating tank F to the positive end of the electroplating tank E and then to the power grid. At this time, the electroplating tank F obtains a reverse voltage, and the electroplating tank E obtains a forward voltage.

[0009] Furthermore, at the moment of t1, the control circuit sends a trigger pulse to the thyristor SCR1 to make the thyristor SCR1 conduct. At this time, the grid voltage all flows from the negative end of the electroplating tank F to the power grid, making the electroplating tank F obtain the maximum reverse voltage, and the electroplating tank E has no voltage until the positive half-cycle of the grid ends at the moment of t2.

[0010] In some embodiments, when the lower part of the electroplating tank is positive and the upper part is negative, when the input voltage is in the negative half-cycle, since the voltage on the thyristor SCR1 is always in the reverse direction and cannot conduct, the thyristor SCR1 is equivalent to an open circuit (the equivalent circuit is as Figure 4 shown).

[0011] Furthermore, in the period from t2 to t3, the thyristor SCR2 is in the cut-off state, and the current flows from the negative end of the electroplating tank E to the positive end of the electroplating tank F and then to the power grid. At this time, the electroplating tank E obtains a reverse voltage, and the electroplating tank F obtains a forward voltage.

[0012] Furthermore, at the moment of t3, the control circuit sends a trigger pulse to the thyristor SCR2 to make the thyristor SCR2 conduct. At this time, the grid voltage all flows from the negative end of the electroplating tank E to the power grid, making the electroplating tank E obtain the maximum reverse voltage, and the electroplating tank F has no voltage until the negative half-cycle of the grid ends at the moment of t4.

[0013] Further, both the thyristor SCR1 and the thyristor SCR2 include a ten-turn potentiometer. The adjustment of the time lengths of the time periods 0 - t1, t1 - t2, t2 - t3, and t3 - t4 is achieved by using the ten-turn potentiometer. The time for each turn is approximately 1 millisecond. Therefore, continuous adjustment between 0 - 10 milliseconds can be realized.

[0014] Further, the adjustment of the time lengths of the time periods 0 - t1, t1 - t2, t2 - t3, and t3 - t4 can be adjusted by the user on the machine panel or by the user's host computer.

[0015] Further preferably, the adjustment of the time lengths of the time periods 0 - t1, t1 - t2, t2 - t3, and t3 - t4 is adjusted by the user on the machine panel.

[0016] Further, the anode and cathode pulse duration range of the power supply of the power-frequency asymmetric positive and negative voltage can reach up to 1000000 us for the pulse pause time. Calculated by single polarity, the duty cycle of the power supply can exceed 95%. The power supply can output DC, the production efficiency is increased by 3 times, and the energy consumption is reduced to one-sixth of the original.

[0017] Technical effects:

[0018] 1. The production efficiency is increased by 3 times, and the energy consumption is reduced to one-sixth of the original; 2. Under the same other conditions, when the power-frequency asymmetric positive and negative voltage power supply of the present application is used for thermoelectrochemical oxidation, the thickness of the coating increases; 3. In the electrophoretic treatment after thermoelectrochemical oxidation, since different voltages affect the film thickness, Al(NO3)3 aqueous solution can generate Al(OH)3 colloid under the action of an electric field. Different working voltages result in different electric field strengths between the positive and negative electrodes, and different driving forces for the colloid particles, thus affecting the thickness of the electrophoretic sealing layer. Under the same other conditions, when the power-frequency asymmetric positive and negative voltage power supply of the present application is used for electrophoresis, the thickness of the electrophoretic sealing layer increases. Description of the drawings

[0019] When reading in combination with the following attached Figure 1 drawings, the above and other features of the content of the present application will be more fully described. It can be understood that these drawings only depict several embodiments of the content of the present application, and thus should not be considered as limiting the scope of the content of the present application. By using the drawings, the content of the present application will be described more clearly and in detail.

[0020] Figure 1 It is a system diagram of the power supply circuit of the power-frequency asymmetric positive and negative voltage of the present application.

[0021] Figure 2 This is the main circuit diagram of the power supply circuit for the power frequency asymmetric positive and negative voltages of the present application.

[0022] Figure 3 This is the equivalent circuit diagram when the input voltage of the present application is in the positive half cycle.

[0023] Figure 4 This is the equivalent circuit diagram when the input voltage of the present application is in the negative half cycle. Detailed implementation manners

[0024] The following embodiments are described to assist in understanding the present application. The embodiments are not and should not in any way be construed as limiting the protection scope of the present application.

[0025] In the following description, those skilled in the art will recognize that throughout this discussion, components may be described as separate functional units (which may include sub-units), but those skilled in the art will recognize that various components or portions thereof may be divided into separate components or may be integrated together (including being integrated within a single system or component).

[0026] At the same time, the connections between components or systems are not intended to be limited to direct connections. Instead, the data between these components may be modified, reformatted, or otherwise changed by intermediate components. Additionally, additional or fewer connections may be used. It should also be noted that the terms "coupled", "connected", or "input", "fixed" should be understood to include both direct connections and indirect connections or fixings through one or more intermediate media.

[0027] Embodiment 1:

[0028] A power supply circuit for power frequency asymmetric positive and negative voltages, as Figures 1-4 shown, includes loop a, loop b, and loop c. Loop a, loop b, and loop c are connected in series. Loop a, loop b, and loop c each include a switch S0, a thyristor SCR1, a thyristor SCR2, an electroplating tank E, and an electroplating tank F. By controlling the on / off modes and times of the thyristors SCR1 and SCR2, the waveform of the power frequency asymmetric positive and negative voltages is controlled. The switch S0 remains closed. In the period from 0 to t1, both the thyristors SCR1 and SCR2 are off. In the period from t1 to t2, the thyristor SCR1 is on and the thyristor SCR2 remains off. In the period from t2 to t3, both the thyristors SCR1 and SCR2 are off. In the period from t3 to t4, the thyristor SCR1 is off and the thyristor SCR2... to complete one waveform cycle, and this cycle repeats.

[0029] When the lower part of the electroplating tank is positive and the upper part is negative, when the input voltage is in the positive half cycle, since the voltage on the thyristor SCR2 is always in the reverse direction and it is impossible to conduct, the thyristor SCR2 is equivalent to an open circuit (the equivalent circuit is as Figure 3As shown. During the time period from 0 to t1, the thyristor SCR1 is in the cut-off state. The current flows from the negative terminal of the electroplating bath F to the positive terminal of the electroplating bath E and then to the power grid. At this time, the electroplating bath F receives a reverse voltage, and the electroplating bath E receives a forward voltage. At the moment t1, the control circuit sends a trigger pulse to the thyristor SCR1 to make the thyristor SCR1 conduct. At this time, the entire grid voltage flows from the negative terminal of the electroplating bath F to the power grid, causing the electroplating bath F to receive the maximum reverse voltage, and the electroplating bath E has no voltage until the moment t2 when the positive half-cycle of the power grid ends.

[0030] When the lower part of the electroplating bath is positive and the upper part is negative, when the input voltage is in the negative half-cycle, since the voltage on the thyristor SCR1 is always in the reverse direction and cannot conduct, the thyristor SCR1 is equivalent to an open circuit (the equivalent circuit is as Figure 4 shown). During the time period from t2 to t3, the thyristor SCR2 is in the cut-off state. The current flows from the negative terminal of the electroplating bath E to the positive terminal of the electroplating bath F and then to the power grid. At this time, the electroplating bath E receives a reverse voltage, and the electroplating bath F receives a forward voltage. At the moment t3, the control circuit sends a trigger pulse to the thyristor SCR2 to make the thyristor SCR2 conduct. At this time, the entire grid voltage flows from the negative terminal of the electroplating bath E to the power grid, causing the electroplating bath E to receive the maximum reverse voltage, and the electroplating bath F has no voltage until the moment t4 when the negative half-cycle of the power grid ends. Both the thyristor SCR1 and the thyristor SCR2 contain a ten-turn potentiometer. The adjustment of the time lengths of the time periods from 0 to t1, from t1 to t2, from t2 to t3, and from t3 to t4 is adjusted by using the ten-turn potentiometer. The time for each turn is approximately 1 millisecond. Therefore, continuous adjustment between 0 and 10 milliseconds can be achieved. The adjustment of the time lengths of the time periods from 0 to t1, from t1 to t2, from t2 to t3, and from t3 to t4 is adjusted by the user on the machine panel. The anode and cathode pulse duration range of the power supply of the power frequency asymmetric positive and negative voltage can reach up to 1000000 us, and calculated by single polarity, the duty cycle of the power supply can exceed 95%. The power supply can output DC, the production efficiency is increased by 3 times, and the energy consumption is reduced to one-sixth of the original.

[0031] During thermoelectrochemical oxidation, when using the power supply of the power frequency asymmetric positive and negative voltage of the present application (sample group), compared with the traditional power supply (control group), in the electrolyte: a solution of 20% Na2SiO3, 25% NaClO3, and 5% KOH, the temperature of the electrolyte is 25 °C, and the thermoelectrochemical oxidation time of the flat aluminum wire in the plating bath is 100 seconds. The thickness of the ceramic layer on the surface of the flat aluminum wire in the sample group is 60 um, and the thickness of the ceramic layer on the surface of the flat aluminum wire in the control group is 25 μm.

[0032] Although the present application has disclosed multiple aspects and embodiments, other aspects and embodiments will be obvious to those skilled in the art. Without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. The multiple aspects and embodiments disclosed in the present application are only for illustrative purposes and are not intended to limit the present application. The actual protection scope of the present application is subject to the claims.

Claims

1. A power supply circuit with asymmetrical positive and negative voltages at a power frequency, characterized in that: It includes loop a, loop b and loop c. Loop a, loop b and loop c are connected in series. Loop a, loop b and loop c each include a switch S0, thyristor SCR1, thyristor SCR2, electroplating tank E and electroplating tank F. By controlling the on-off mode and time of thyristor SCR1 and thyristor SCR2, the waveform of the power frequency asymmetric positive and negative voltage is controlled. Switch S0 remains closed. During the time period 0-t1, thyristor SCR1 and thyristor SCR2 are both disconnected. During the time period t1-t2, thyristor SCR1 is closed and thyristor SCR2 remains disconnected. During the time period t2-t3, thyristor SCR1 and thyristor SCR2 are both disconnected. During the time period t3-t4, thyristor SCR1 is disconnected and thyristor SCR2 is closed, completing a waveform cycle. Ring, thyristor SCR1 and thyristor SCR2 both contain a ten-turn potentiometer, which adjusts the length of the 0-t1 time period, t1-t2 time period, t2-t3 time period and t3-t4 time period. The ten-turn potentiometer is used to adjust the time. Each turn is 1 millisecond, so continuous adjustment from 0 to 10 milliseconds can be achieved. The length of the 0-t1 time period, t1-t2 time period, t2-t3 time period and t3-t4 time period can be adjusted by the user on the machine panel or by the user's host computer. The anode and cathode pulse duration range and pulse pause time of the power supply with asymmetrical positive and negative voltage of the industrial frequency can reach up to 1000000us. Calculated as a single polarity, the duty cycle of the power supply can exceed 95%, and the power supply can output DC.

2. The power supply circuit of industrial frequency asymmetric positive and negative voltage according to claim 1, characterized in that: When the bottom of the electroplating tank is positive and the top is negative, when the input voltage is in the positive half cycle, since the voltage on the thyristor SCR2 is always in the reverse direction, it is impossible to conduct, and the thyristor SCR2 is equivalent to an open circuit.

3. The power supply circuit of industrial frequency asymmetric positive and negative voltage according to claim 2, characterized in that: During the time period 0-t1, the thyristor SCR1 is in the cut-off state, and the current flows from the negative end of the electroplating tank F to the positive end of the electroplating tank E, and then flows to the power grid. At this time, the electroplating tank F obtains a reverse voltage, and the electroplating tank E obtains a forward voltage.

4. The power supply circuit of industrial frequency asymmetric positive and negative voltage according to claim 3, characterized in that: At time t1, the control circuit sends a trigger pulse to the thyristor SCR1, turning on the thyristor SCR1. At this time, the grid voltage flows entirely from the negative end of the electroplating tank F to the grid, so that the electroplating tank F obtains the maximum reverse voltage, and the electroplating tank E has no voltage until time t2, when the positive half cycle of the grid ends.

5. The power supply circuit of industrial frequency asymmetric positive and negative voltage according to claim 1, characterized in that: When the bottom of the electroplating tank is positive and the top is negative, when the input voltage is in the negative half cycle, since the voltage on the thyristor SCR1 is always in the reverse direction, it is impossible to conduct, and the thyristor SCR1 is equivalent to an open circuit.

6. The power supply circuit of industrial frequency asymmetric positive and negative voltage according to claim 5, characterized in that: During the time period t2-t3, the thyristor SCR2 is in the cut-off state, and the current flows from the negative end of the electroplating tank E to the positive end of the electroplating tank F, and then flows to the power grid. At this time, the electroplating tank E obtains a reverse voltage, and the electroplating tank F obtains a forward voltage.

7. The power supply circuit of industrial frequency asymmetric positive and negative voltage according to claim 6, characterized in that: At time t3, the control circuit sends a trigger pulse to the thyristor SCR2, turning on the thyristor SCR2. At this time, the grid voltage flows entirely from the negative end of the electroplating tank E to the grid, so that the electroplating tank E obtains the maximum reverse voltage, and the electroplating tank F has no voltage until time t4, when the negative half cycle of the grid ends.

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