A variable-frequency pulse power supply for electro-desalting and a method for generating the same

Abstract

The present invention discloses a variable-frequency pulse power supply for electro-desalting and a method for generating the same. A master-slave dual-inverter device is adopted. The first inverter device is connected to low-voltage alternating current, and the second inverter device is connected to an energy storage capacitor. The first inverter device provides a bipolar low-voltage pulse power supply in the positive cycle, and then performs step-up processing through a pulse transformer to form a high-voltage DC pulse power supply. When the current of the low-voltage pulse power supply in the positive cycle or the negative cycle reaches the upper limit value, the energy storage capacitor absorbs the freewheeling energy of the pulse transformer device through the slave inverter device; after the energy storage capacitor stores energy, the second inverter device and the first inverter device superimpose and output a low-voltage pulse power supply. Through this generation method, the freewheeling energy of the pulse transformer device during the output of the low-voltage pulse power supply can be recovered, and the power supply efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electro - desalting, and particularly to a variable - frequency pulse power supply for electro - desalting and a method for generating the same. Background Art

[0002] Crude oil contains water, as well as natural emulsifiers such as resins and asphaltenes. During the exploitation and transportation of crude oil, due to intense agitation, water is dispersed in the crude oil in the form of micro - droplets. The emulsifiers in the crude oil are concentrated at the oil - water interface by adsorption, forming a firm molecular film and a stable emulsion. The stability of the emulsion depends on factors such as the nature of the emulsifier, its concentration, the nature of the crude oil itself, the degree of water dispersion, and the length of time for emulsion formation. Strong mechanical agitation, a high concentration of emulsifier, a high viscosity of the crude oil, and a long formation time of the emulsion will increase the stability of the emulsion. Electro - desalting of crude oil mainly involves adding a demulsifier to destroy its emulsified state. Under the action of an electric field, tiny water droplets coalesce into large water droplets, enabling the separation of oil and water. Since most of the salts in crude oil are dissolved in water, desalting and dehydration are carried out simultaneously.

[0003] Crude oil dehydration and desalting require a high - power power supply to provide a high voltage and a strong electric field to complete the oil - water separation, resulting in high energy consumption. Currently, electro - desalting technology usually uses an inverter device to output a high - voltage pulse power supply for pulse desalting to achieve high - efficiency energy conservation, but the energy consumption is still very high. Therefore, technicians in this field are still continuously improving to further enhance the energy efficiency of electro - desalting technology.

[0004] Inverters all use a full - bridge or half - bridge to form a power conversion circuit and work based on the area - equivalence principle. The control terminal modulates the carrier wave and the target waveform into PWM together and finally outputs the target waveform through an inertia link. Its implementation of pulses basically adopts an intermittent power - supply method, resulting in large pulse distortion. The switching frequency of the power device is several times the output frequency, and the reliability is poor. Summary of the Invention

[0005] In view of the above - mentioned defects of the prior art, the problem to be solved by the present invention is: how to improve the efficiency of the inverter output of the variable - frequency pulse power supply and improve the reliability.

[0006] The variable - frequency pulse power supply for electro - desalting of the present invention controls the output of the inverter not by using the area - equivalence principle, but by adopting a pure - pulse output method in which the carrier wave is the target waveform. The generated pulse waveform does not pass through an inertia link, and the switching frequency is the output frequency, reducing the switching frequency of the inverter power device, improving the reliability of the inverter power device. The output pulse is a true pulse without passing through any link, and the pulse efficiency can be as high as 98%.

[0007] The present invention also adopts the cascading method of two H-bridge inverter modules, which can work in the following modes: the two inverter modules output pulses in series simultaneously (to increase the pulse peak voltage), the two inverter modules are instantaneously connected in parallel (the output frequency is doubled at the same switching frequency, greatly improving the reliability of the inverter), and the two modules are in mutual hot standby: when one module fails, the other module automatically supplies power for output.

[0008] In normal cascaded inversion, each inverter module needs to separately provide isolated DC power supplies. In the present invention, only one of the modules supplies the DC power, and the other module automatically extracts the DC bus voltage from the main circuit, reducing the power supply circuit of the system, lowering the cost, and making the system more reliable.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A variable-frequency pulse power supply for electro-desalting, comprising:

[0011] A low-voltage DC power supply device, including a rectifier and a filtering device, for rectifying and filtering low-voltage alternating current and outputting a first low-voltage DC power supply with an adjusted amplitude;

[0012] An energy storage device, for storing energy in a reverse cycle and outputting a second low-voltage DC power supply after completing the energy storage;

[0013] A first inverter device, connected to the first low-voltage DC power supply device, for inverting the first low-voltage DC power supply;

[0014] A second inverter device, connected to the energy storage device, for providing a path for the energy storage device to store energy in a reverse cycle or for inverting the second low-voltage DC power supply; cascaded with the first inverter device, and outputting a low-voltage pulse power supply with an adjusted amplitude through duty cycle modulation, the low-voltage pulse power supply being a bipolar low-voltage pulse power supply or a multi-polar low-voltage pulse power supply;

[0015] A pulse transformer device, connected to the cascaded first inverter device and second inverter device, for boosting the low-voltage pulse power supply and outputting a high-voltage pulsed DC power supply; the reactance value at the input end of the pulse transformer device is matched with the capacitance value of the energy storage device;

[0016] A detection device, for monitoring the current and voltage of the low-voltage pulse power supply and obtaining output parameters;

[0017] A control device, respectively connected to the first low-voltage DC power supply device, the first inverter device, the second inverter device, and the detection device, for controlling the timing of the energy storage device to store energy in a reverse cycle, and adjusting the amplitude of the low-voltage DC power supply, the amplitude and frequency of the low-voltage pulse power supply according to the output parameters.

[0018] Further, the matching formula for the reactance value at the input end of the pulse transformer device to match the capacitance value of the energy storage device is: C = (L * I) / (U 2 ), where: C is the capacitance value of the energy storage device, L is the reactance value of the primary of the pulse transformer device, I is the instantaneous average value of the current flowing through the primary of the pulse transformer device, and U is the voltage for charging the energy storage device.

[0019] Further, both the first inverter device and the second inverter device include a set of H-bridge inverters and inverter drive circuits. The control device drives the H-bridge inverters through the inverter drive device, and protection diodes are connected in parallel with the switching tubes of the H-bridge inverters.

[0020] Further, all the switching tubes of the H-bridge inverter are all MOS tubes or all IGBT transistors.

[0021] Further, the energy storage device and the filtering device are capacitor banks.

[0022] Further, the rectifier is a three-phase thyristor rectifier.

[0023] Further, the control device includes:

[0024] A parameter acquisition module, connected to the detection device, for receiving output parameters from the detection device;

[0025] A first low-voltage DC power supply control module, connected to the first low-voltage DC power supply device, for adjusting the amplitude of the first low-voltage DC power supply;

[0026] A pulse width modulation module, connected to the first inverter device and the second inverter device, for adjusting the amplitude of the bipolar low-voltage pulse power supply by pulse width modulation;

[0027] A central processing module, respectively connected to the parameter acquisition module, the first low-voltage DC power supply control module, and the pulse width modulation module, for controlling the amplitude of the first low-voltage DC power supply output by the first low-voltage DC power supply device through the low-voltage DC power supply control module according to the output parameters, controlling the low-voltage pulse power supply cascadedly output by the first inverter device and the second inverter device through the pulse width modulation module, and controlling the timing of the energy storage device for counter-cycle energy storage.

[0028] To achieve the above object, the present invention also provides a method for generating a variable-frequency pulse power supply, which is applied to the variable-frequency pulse power supply as described above, and includes:

[0029] The first cycle: Set the first inverter device to the chopping mode, set the second inverter device to the bypass mode, and the first inverter device provides a low-voltage pulse power supply for the positive cycle; The pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply;

[0030] The second cycle: When the current of the low-voltage pulse power supply in the positive cycle reaches the upper limit value, set the first inverter device to the bypass mode, turn off all the switching tubes of the second inverter device, and the freewheeling energy of the pulse transformer device charges the energy storage device through the protection diodes of the switching tubes of the second inverter device;

[0031] The third cycle: Set the first inverter device to the chopping mode, set the second inverter device to the bypass mode, and the first inverter device provides a low-voltage pulse power supply for the negative cycle; The pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply;

[0032] The fourth cycle: When the current of the low-voltage pulse power supply in the negative cycle reaches the upper limit value, set the first inverter device to the bypass mode, turn off all the switching tubes of the second inverter device, and the freewheeling energy of the pulse transformer device charges the energy storage device through the protection diodes of the switching tubes;

[0033] The fifth cycle: Set the first inverter device to the chopping mode, set the second inverter device to the chopping mode, and the first inverter device provides a low-voltage pulse power supply for the positive cycle; The pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply; The first inverter device and the second inverter device are connected in series to jointly output a voltage, providing a low-voltage series superimposed pulse power supply for the positive cycle;

[0034] The sixth cycle: Set the first inverter device to the chopping mode, set the second inverter device to the chopping mode, and the first inverter device provides a low-voltage pulse power supply for the negative cycle; The pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply; The first inverter device and the second inverter device are connected in series to jointly output a voltage, providing a low-voltage series superimposed pulse power supply for the negative cycle;

[0035] The chopping mode is the single-pulse output control of the inverter device, establishing a positive cycle path from the positive pole of the inverter device - the first output - the second output - the lower bridge arm - the negative pole of the inverter device, or establishing a negative cycle path from the positive pole of the inverter device - the second output - the first output - the lower bridge arm - the negative pole of the inverter device;

[0036] The bypass mode is to short-circuit the two outputs of the inverter device through the conduction control of the switching tubes of the two upper bridge arms or the two lower bridge arms of the inverter device.

[0037] The present invention provides a variable-frequency pulse power supply for electro-desalting and a method for generating the same. A master-slave dual-channel inverter device is adopted. The first inverter device is connected to low-voltage alternating current, and the second inverter device is connected to an energy storage device. The first inverter device provides a bipolar low-voltage pulse power supply in the positive cycle, and then performs a boosting process through a pulse transformer to form a high-voltage DC pulse power supply. When the current of the low-voltage pulse power supply in the positive cycle reaches the upper limit value, the energy storage device absorbs the freewheeling energy of the pulse transformer device through the slave inverter device; the second inverter device extracts the stored energy of the energy storage device and outputs a bipolar low-voltage pulse power supply in the negative cycle. Through this generation method, the freewheeling energy of the pulse transformer device during the output of the low-voltage pulse power supply can be recovered, and the power supply efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a system block diagram of the variable-frequency pulse power supply of the present invention;

[0039] Figure 2 is a circuit diagram of the variable-frequency pulse power supply according to an embodiment of the present invention;

[0040] Figure 3 is a waveform diagram of the low-voltage pulse power supply according to an embodiment of the present invention.

[0041] Reference numerals:

[0042] 1, three-phase rectifier; 2, first capacitor; 3, first inverter device; 4, second capacitor; 5, second inverter device; 6, DSP controller; 7, detection device; 8, pulse transformer device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] To further illustrate the embodiments, the present invention provides accompanying drawings. These drawings are a part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used to explain the operating principle of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0044] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0045] As Figures 1-3 shown, the present invention discloses a variable-frequency pulse power supply for electro-desalting, whose input is connected to 380V three-phase alternating current, and includes functional modules such as a three-phase rectifier 1, a first capacitor 2, a first inverter device 3, a second capacitor 4, a second inverter device 5, a DSP controller 6, a detection device 7, and a pulse transformer device 8.

[0046] Among them, the three-phase rectifier 1 and the first capacitor 2 form a low-voltage DC power supply device, which rectifies and filters the input low-voltage alternating current and outputs the first low-voltage DC power supply with an adjusted amplitude; in this embodiment, the three-phase rectifier is a three-phase thyristor rectifier, and the amplitude of the first low-voltage DC power supply is adjusted by controlling the thyristor trigger angle.

[0047] The second capacitor 4 is used for counter-cycle energy storage and outputs the second low-voltage DC power supply after the energy storage is completed; both the first capacitor 2 and the second capacitor 4 are capacitor banks.

[0048] The first inverter device 3 is connected to the first capacitor 2 and is used for inverting the first low-voltage DC power supply.

[0049] The second inverter device 5 is connected to the second capacitor 4 and is used to provide a path for the counter-cycle energy storage of the second capacitor 4 or to invert the second low-voltage DC power supply; it is cascaded with the first inverter device 3 and outputs a low-voltage pulse power supply with an adjusted amplitude through duty cycle modulation.

[0050] The pulse transformer device 8 is connected to the cascaded first inverter device 3 and second inverter device 5 and is used for boosting the low-voltage pulse power supply and outputting a high-voltage pulsed DC power supply; in this application, the reactance value at the input end of the pulse transformer device 8 is matched with the capacitance value of the second capacitor 4, so as to oscillate. The matching formula for the reactance value and the capacitance value is: C = (L * I) / (U 2 ), where: C is the capacitance value of the second capacitor 4, L is the reactance value at the input end of the pulse transformer device 8, I is the instantaneous average value of the current flowing through the primary of the transformer, and U is the voltage for capacitor charging.

[0051] The detection device 7 is a set of voltage and current detection circuits and is used to monitor the current and voltage of the low-voltage pulse power supply and obtain the output parameters.

[0052] The DSP controller 6 is respectively connected to the low-voltage DC power supply device, the first inverter device 3, the second inverter device 5 and the detection device 7, and is used to control the timing of the counter-cycle energy storage of the energy storage device and adjust the amplitude of the low-voltage DC power supply, the amplitude and frequency of the low-voltage pulse power supply according to the output parameters.

[0053] In this embodiment, the low-voltage alternating current refers to 380V alternating current. In the crude oil electro-desalting application of this embodiment, the voltage of the high-voltage DC pulsed power supply is dozens of kilovolts.

[0054] As Figure 2 shown, the first inverter device 3 and the second inverter device 5 are cascaded, and the specific description is as follows.

[0055] Both the first inverter device 3 and the second inverter device 5 include a set of H-bridge inverters and inverter drive circuits, and the DSP controller 6 drives the H-bridge inverters through the inverter drive device.

[0056] The H-bridge inverter of the first inverter device 3 is composed of four switching tubes S1, S2, S3, and S4. The switching tubes can be MOS tubes (insulated gate field effect transistors) or IGBT transistors (insulated gate bipolar transistors). The switching tubes are all equipped with protection diodes connected across the source and drain. Among them, the switching tubes S1 and S3 are connected to the positive power supply of the first inverter device 3, and the switching tubes S2 and S4 are connected to the negative power supply of the first inverter device 3.

[0057] The first output terminal A1 of the first inverter device 3 is led out from the connection between the switching tubes S1 and S2, and the second output terminal B1 is led out from the connection between the switching tubes S3 and S4; it is used to output a bipolar low-voltage pulse power supply U1 with a positive cycle.

[0058] Similarly, the H-bridge inverter of the second inverter device 5 is composed of four switching tubes S5, S6, S7, and S8. Among them, the switching tubes S5 and S7 are connected to the positive power supply of the second inverter device 5, and the switching tubes S6 and S8 are connected to the negative power supply of the second inverter device 5.

[0059] The first output terminal A2 of the second inverter device 5 is led out from the connection between the switching tubes S5 and S6, and the second output terminal B2 is led out from the connection between the switching tubes S7 and S8; it is used to output a bipolar low-voltage pulse power supply with a negative cycle.

[0060] The first inverter device 3 and the second inverter device 5 are cascaded. By controlling the on or off state of the switching tubes, it can be periodically realized that when the first inverter device 3 outputs with a single inverter, the freewheeling energy of the pulse transformer device is stored in the second capacitor 4 to achieve energy storage; after the energy storage of the second capacitor 4, the series superposition output of the first inverter device 3 and the second inverter device 5 is realized.

[0061] In this embodiment, the pulse transformer device 8 includes a pulse transformer.

[0062] As Figure 1 shown, in this embodiment, the control device includes: a parameter acquisition module, a low-voltage DC power supply control module, a pulse width modulation module, and a central processing module, where:

[0063] The parameter acquisition module is connected to the detection device 7 and is used to receive output parameters from the detection device 7; the low-voltage DC power supply control module is connected to the low-voltage DC power supply device and adjusts the amplitude of the first low-voltage DC power supply by controlling the thyristor trigger angle.

[0064] A pulse width modulation module, connected to the first inverter device 3 and the second inverter device 5, adjusts the amplitude of the bipolar low-voltage pulse power supply through pulse width modulation;

[0065] A central processing module, respectively connected to the parameter acquisition module, the low-voltage DC power supply control module, and the pulse width modulation module, is used to control the amplitude of the first low-voltage DC power supply output by the low-voltage DC power supply device through the low-voltage DC power supply control module according to the output parameters, and control the timing of the inverse cycle energy storage of the low-voltage pulse power supply cascaded by the first inverter device 3 and the second inverter device 5 and the second capacitor 4 through the pulse width modulation module.

[0066] Combined with the variable-frequency pulse power supply with a dual-inverter device in this embodiment, the present invention also discloses a method for generating a variable-frequency pulse power supply, including:

[0067] The first cycle: Set the first inverter device to the chopping mode and the second inverter device to the bypass mode, and the first inverter device provides a low-voltage pulse power supply for the positive cycle; the pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply;

[0068] The second cycle: When the current of the low-voltage pulse power supply in the positive cycle reaches the upper limit value, the first inverter device is set to the bypass mode, all the switching tubes of the second inverter device are turned off, and the freewheeling energy of the pulse transformer device charges the energy storage device through the protection diode of the switching tube;

[0069] The third cycle: Set the first inverter device to the chopping mode and the second inverter device to the bypass mode, and the first inverter device provides a low-voltage pulse power supply for the negative cycle; the pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply;

[0070] The fourth cycle: When the current of the low-voltage pulse power supply in the negative cycle reaches the upper limit value, the first inverter device is set to the bypass mode, all the switching tubes of the second inverter device are turned off, and the freewheeling energy of the pulse transformer device charges the energy storage device through the protection diode of the switching tube;

[0071] The fifth cycle: Set the first inverter device to the chopping mode and the second inverter device to the chopping mode, and the first inverter device provides a low-voltage pulse power supply for the positive cycle; the pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply; the first inverter device and the second inverter device are connected in series to jointly output a voltage to provide a low-voltage series superposition pulse power supply for the positive cycle.

[0072] Sixth cycle: Set the first inverter device to the chopping mode, set the second inverter device to the chopping mode, and the first inverter device provides a low-voltage pulse power supply for the negative cycle; a pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply; the first inverter device and the second inverter device are connected in series to jointly output a voltage and provide a low-voltage series superimposed pulse power supply for the negative cycle.

[0073] The output waveform of the low-voltage pulse power supply is as Figure 3 shown, where the pulses of ①②③④⑤⑥ respectively correspond to the pulses generated in the first cycle to the sixth cycle.

[0074] The chopping mode is the single-pulse output control of the inverter device, establishing a positive cycle path from the positive pole of the inverter device - the first output - the second output - the lower bridge arm - the negative pole of the inverter device, or establishing a negative cycle path from the positive pole of the inverter device - the second output - the first output - the lower bridge arm - the negative pole of the inverter device.

[0075] The bypass mode is to short-circuit the two outputs of the inverter device through the conduction control of the switching tubes of the two upper bridge arms or the two lower bridge arms of the inverter device.

[0076] Combined with Figure 2 the circuit diagram is described in detail as follows.

[0077] Both ends of the second capacitor 4 are not connected to an external low-voltage alternating current, and the energy required for the energy storage of the second capacitor 4 is completely obtained by obtaining voltage from the resonance plus rectification that automatically cuts into the first inverter device 3 and the pulse transformer device 8 at certain times.

[0078] (1) First cycle: The switching tubes S2 and S3 are turned on, the switching tubes S6 and S8 are turned on, and the rest of the switching tubes are turned off. That is, the first inverter device 3 is set to the chopping mode, the second inverter device 5 is set to the bypass mode, and the load is completely powered by the first inverter device 3 with a positive voltage, providing a low-voltage pulse power supply for the positive cycle. At this time, the current flowing through the pulse transformer device 8 (the current of the positive cycle low-voltage pulse power supply) slowly increases.

[0079] (2) Second cycle: When the current of the positive cycle low-voltage pulse power supply reaches the allowed maximum value, the first inverter device 3 switches to S1 and S3 being turned off, and S2 and S4 being turned on. At the same time, the second inverter device 5 turns off all the switching tubes, that is, the first inverter device 3 is set to the bypass mode, and the second inverter device 5 is in the off state. In this way, the energy for freewheeling in the pulse transformer device 8 flows through the switching tubes S2 and S4, the protection diodes of the switching tube S5, and the protection diode of the switching tube S8 to the second capacitor 4, and the second capacitor 4 stores energy. By controlling the capacitance value of the second capacitor 4 to match the reactance value of the pulse transformer device 8 and making it work in the resonant state, the excess freewheeling current during the operation of the pulse transformer device 8 can be quickly stored at both ends of the second capacitor 4, and this stored electrical quantity is used to provide the energy for the next pulse generation.

[0080] (3) Third cycle: The switching tubes S1 and S4 are turned on, and the switching tubes S6 and S8 are turned on, and the rest of the switching tubes are turned off, that is, the first inverter device 3 is set to the chopping mode, and the second inverter device 5 is set to the bypass mode. The load is completely supplied with negative voltage by the first inverter device 3 to work, providing a low-voltage pulse power supply for the negative cycle. At this time, the current flowing through the pulse transformer device 8 (the current of the negative cycle low-voltage pulse power supply) slowly increases.

[0081] (4) Fourth cycle: When the current of the negative cycle low-voltage pulse power supply reaches the allowed maximum value, the first inverter device 3 switches to the switching tubes S2 and S4 being turned off, and the switching tubes S1 and S3 being turned on. At the same time, the second inverter device 5 turns off all the switching tubes, that is, the first inverter device 3 is set to the bypass mode, and the second inverter device 5 is in the off state. In this way, the energy for freewheeling in the pulse transformer device 8 flows through the switching tubes S1 and S3, the protection diodes of the switching tubes S5 and S8 to the second capacitor 4, and the second capacitor 4 stores energy.

[0082] By controlling the capacitance value of the second capacitor 4 to match the reactance value of the pulse transformer device 8 and making it work in the resonant state, the excess freewheeling current during the operation of the pulse transformer device 8 can be quickly stored at both ends of the second capacitor 4, and this stored electrical quantity is used to provide the energy for the next pulse generation.

[0083] (5) Fifth cycle: The switching tubes S2 and S3 are turned on, and the switching tubes S6 and S7 are turned on, and the rest of the switching tubes are turned off, that is, the first inverter device 3 is set to the chopping mode, and the second inverter device 5 is set to the chopping mode. The load is supplied with voltage by the series connection of the first inverter device 3 and the second inverter device 5 to work, providing a positive cycle low-voltage series superposition pulse power supply.

[0084] (6) The sixth cycle: Switching tubes S1 and S4 are turned on, switching tubes S5 and S8 are turned on, and the remaining switching tubes are turned off. That is, the first inverter device 3 is set to the chopping mode, the second inverter device 5 is set to the chopping mode, and the load is powered by the series connection of the first inverter device 3 and the second inverter device 5 to provide a low-voltage series superposition pulse power supply for the negative cycle.

[0085] The method for generating the variable-frequency pulse power supply of the present invention uses a master-slave dual-channel inverter device. The first inverter device is connected to low-voltage alternating current, and the second inverter device is connected to an energy storage capacitor. The first inverter device provides a bipolar low-voltage pulse power supply in the positive cycle, and then performs a boosting process through a pulse transformer to form a high-voltage DC pulse power supply. When the current of the low-voltage pulse power supply in the positive cycle reaches the upper limit value, the energy storage capacitor absorbs the freewheeling energy of the pulse transformer device through the slave inverter device; the second inverter device extracts the stored energy of the energy storage capacitor in the negative cycle and outputs a bipolar low-voltage pulse power supply. Through this generation method, the freewheeling energy of the pulse transformer device during the output of the low-voltage pulse power supply can be recovered, and the power efficiency can be improved.

[0086] Although the present invention is specifically shown and described in conjunction with the preferred embodiments, those skilled in the art should understand that various changes can be made to the present invention in terms of form and details without departing from the spirit and scope of the present invention defined by the appended claims, and all of them are within the protection scope of the present invention.

Claims

1. A method for generating a variable-frequency pulse power supply, which is used for the variable-frequency pulse power supply of electro-desalting, and is characterized in that, The variable-frequency pulse power supply for electro-desalting includes: A low-voltage DC power supply device, including a rectifier and a filtering device, which is used to rectify and filter the low-voltage alternating current and output a first low-voltage DC power supply with an adjusted amplitude; An energy storage device, which is used to store energy in a reverse cycle and output a second low-voltage DC power supply after the energy storage is completed; A first inverter device, connected to the first low-voltage DC power supply device, which is used to invert the first low-voltage DC power supply; A second inverter device, connected to the energy storage device, which is used to provide a path for the energy storage device to store energy in a reverse cycle or invert the second low-voltage DC power supply; cascaded with the first inverter device, and output a low-voltage pulse power supply with an adjusted amplitude through duty cycle modulation. The low-voltage pulse power supply is a bipolar low-voltage pulse power supply or a multi-polar low-voltage pulse power supply; A pulse transformer device, connected to the cascaded first inverter device and second inverter device, which is used to boost the low-voltage pulse power supply and output a high-voltage pulsed DC power supply; the reactance value at the input end of the pulse transformer device matches the capacitance value of the energy storage device; A detection device, which is used to monitor the current and voltage of the low-voltage pulse power supply and obtain output parameters; A control device, respectively connected to the first low-voltage DC power supply device, the first inverter device, the second inverter device, and the detection device, which is used to control the timing of the energy storage device to store energy in a reverse cycle, and adjust the amplitude of the first low-voltage DC power supply, the amplitude and frequency of the low-voltage pulse power supply according to the output parameters; The method for generating the variable-frequency pulse power supply includes: The first cycle: Set the first inverter device to the chopping mode and the second inverter device to the bypass mode, and the first inverter device provides a low-voltage pulse power supply in the positive cycle; the pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply; The second cycle: When the current of the low-voltage pulse power supply in the positive cycle reaches the upper limit value, set the first inverter device to the bypass mode, turn off all the switching tubes of the second inverter device, and the freewheeling energy of the pulse transformer device charges the energy storage device through the protection diode of the switching tube; The third cycle: Set the first inverter device to the chopping mode and the second inverter device to the bypass mode, and the first inverter device provides a low-voltage pulse power supply in the negative cycle; the pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply; The fourth cycle: When the current of the low-voltage pulse power supply in the negative cycle reaches the upper limit value, set the first inverter device to the bypass mode, turn off all the switching tubes of the second inverter device, and the freewheeling energy of the pulse transformer device charges the energy storage device through the protection diode of the switching tube; The fifth cycle: Set the first inverter device to the chopping mode and the second inverter device to the chopping mode, and the first inverter device provides a low-voltage pulse power supply in the positive cycle; the pulse transformer device boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply; the first inverter device and the second inverter device are connected in series to jointly output a voltage and provide a low-voltage series superposition pulse power supply in the positive cycle; Sixth cycle: Set the first inverter device to the chopping mode, set the second inverter device to the chopping mode, and the first inverter device provides a low-voltage pulse power supply for the negative cycle; a pulse transformer device that boosts the low-voltage pulse power supply and outputs a high-voltage pulsed DC power supply; the first inverter device and the second inverter device are connected in series to jointly output a voltage to provide a low-voltage series superimposed pulse power supply for the negative cycle. The chopping mode is the single-pulse output control of the inverter device, establishing a positive cycle path from the positive pole of the inverter device - the first output - the second output - the lower bridge arm - the negative pole of the inverter device, or establishing a negative cycle path from the positive pole of the inverter device - the second output - the first output - the lower bridge arm - the negative pole of the inverter device. The bypass mode is to short-circuit the two outputs of the inverter device through the conduction control of the switch tubes of the two upper bridge arms or the two lower bridge arms of the inverter device.

2. The method for generating a variable-frequency pulse power supply according to claim 1, and is characterized in that, The matching formula for the reactance value at the input end of the pulse transformer device to match the capacitance value of the energy storage device is: C = (L * I) / (U²), where: C is the capacitance value of the energy storage device, L is the reactance value of the primary of the pulse transformer device, I is the instantaneous average value of the current flowing through the primary of the pulse transformer device, and U is the voltage for charging the energy storage device.

3. The method for generating a variable-frequency pulse power supply according to claim 1, and is characterized in that, Both the first inverter device and the second inverter device include a set of H-bridge inverters and inverter drive circuits. The control device drives the H-bridge inverters through the inverter drive circuits, and protection diodes are connected in parallel with the switch tubes of the H-bridge inverters.

4. The method for generating a variable-frequency pulse power supply according to claim 3, and is characterized in that, All the switch tubes of the H-bridge inverter are MOS tubes or all are IGBT transistors.

5. The method for generating a variable-frequency pulse power supply according to claim 1, and is characterized in that, The energy storage device and the filtering device are capacitor banks.

6. The method for generating a variable-frequency pulse power supply according to claim 1, and is characterized in that, The rectifier is a three-phase thyristor rectifier.

7. The method for generating a variable-frequency pulse power supply according to any one of claims 1-6, and is characterized in that, The control device includes: A parameter acquisition module, connected to the detection device, for receiving output parameters from the detection device. A first low-voltage DC power supply control module, connected to the first low-voltage DC power supply device, for adjusting the amplitude of the first low-voltage DC power supply. A pulse width modulation module, connected to the first inverter device and the second inverter device, for adjusting the amplitude of the bipolar low-voltage pulse power supply by pulse width modulation. A central processing module, respectively connected to the parameter acquisition module, the low-voltage DC power supply control module, and the pulse width modulation module, for controlling the amplitude of the first low-voltage DC power supply output by the low-voltage DC power supply device through the low-voltage DC power supply control module according to the output parameters, controlling the low-voltage pulse power supply cascaded by the first inverter device and the second inverter device through the pulse width modulation module, and controlling the timing of the energy storage of the energy storage device in the reverse cycle.

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