Energy feedback type bipolar current pulse generation circuit structure and method

Abstract

The application discloses an energy feedback type bipolar current pulse generation circuit structure, comprising an input filter capacitor Cin, a first thyristor S1, a second thyristor S2, a lithium battery Buck converter, a super capacitor energy storage full-bridge module valve group, an output filter capacitor Co and a thyristor commutation circuit; a positive electrode of a DC bus is connected with anodes of the first thyristor S1 and the second thyristor S2, and a negative electrode of the input DC bus is connected with a lower terminal of the super capacitor energy storage full-bridge module; a cathode of the first thyristor S1 is connected with a cathode of the lithium battery; an upper terminal of the output capacitor Co is connected with a right terminal of a first filter inductor L1 of the lithium battery Buck converter and an upper terminal of the thyristor commutation circuit; a lower terminal of the output capacitor Co is connected with a lower terminal of the super capacitor energy storage full-bridge module valve group and a lower terminal of the thyristor commutation circuit; and a corresponding generation method is also disclosed; the device voltage stress can be effectively reduced, a higher output voltage can be realized, and the energy utilization efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, in particular to an energy feedback type bipolar current pulse generation circuit structure. BACKGROUND

[0002] The inductive load bipolar current pulse generation device is a core component of a magnetic field generating device such as a strong magnetic field generator and an industrial nondestructive testing instrument. In actual application, the frequency and amplitude of the bipolar current pulse need to be adjusted to control the frequency and strength of the magnetic field generated by the magnetic field generating coil.

[0003] The time constant of the large inductive load is large. In order to obtain a magnetic field with higher frequency and strength, the voltage across the inductive load needs to be further increased, and the current change rate during the rising process of the pulse current needs to be increased, so that the inductive load current reaches the steady state as soon as possible to generate the required magnetic field. Therefore, the voltage regulation range of the bipolar current pulse generation circuit needs to be wide. At the same time, a large amount of energy needs to be absorbed by the corresponding circuit during the falling process of the pulse current.

[0004] The existing bipolar pulse current generation topology is limited by the voltage resistance of a single switching device, and it is difficult to generate a bipolar pulse current with a high rise rate and a high amplitude. At the same time, due to the lack of energy recovery during the falling process of the pulse current, the energy utilization rate of the circuit is low. Therefore, how to obtain a current pulse with the required width / height and rise / fall time without increasing the voltage resistance of the device, and how to achieve efficient energy recovery without adding additional energy dissipation devices, are a series of problems that need to be solved at present. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide an energy feedback type bipolar current pulse generation circuit and a control method thereof, which solves the problem of difficulty in obtaining a bipolar pulse current with a high rise rate and a high amplitude under the condition of a large inductive load, and realizes efficient energy recovery.

[0006] To solve the above problems, the technical scheme adopted by the present application is as follows:

[0007] An energy feedback type bipolar current pulse generation circuit structure, comprising an input filter capacitor Cin, a first thyristor S1, a second thyristor S2, a lithium battery Buck converter, a super capacitor energy storage full-bridge module, an output filter capacitor Co and a thyristor commutation circuit.

[0008] The anode of the input DC bus is connected with the anodes of the first thyristor S1 and the second thyristor S2, and the negative pole of the input DC bus is connected with the lower terminal of the super capacitor energy storage full-bridge module; the cathode of the first thyristor S1 is connected with the cathode of the lithium battery in the lithium battery Buck converter; the upper terminal of the output capacitor Co is connected with the right terminal of the first filter inductor L1 of the lithium battery Buck converter and the upper terminal of the thyristor commutation circuit; and the lower terminal of the output capacitor Co is connected with the lower terminal of the super capacitor energy storage full-bridge module valve group and the lower terminal of the thyristor commutation circuit.

[0009] Further, the lithium battery Buck converter comprises a lithium battery A, a first Buck switch tube S, a first diode D1 and a first filter inductor L1; the anode of the lithium battery A is connected with the emitter of the first Buck switch tube S, and the cathode of the lithium battery is connected with the anode of the first diode D1; the collector of the first Buck switch tube S is connected with the cathode of the first diode D1 and the left terminal of the first filter inductor L1.

[0010] Further, the super capacitor energy storage full-bridge module valve group is composed of n full-bridge sub-modules connected in series, and n is a positive integer greater than or equal to 3.

[0011] Further, the full-bridge sub-module comprises a first switch tube SN1, a second switch tube SN2, a third switch tube SN3, a fourth switch tube SN4 and a sub-module capacitor C N ; the emitter of the first switch tube SN1 and the collector of the second switch tube SN2 are connected to form a first bridge arm, the emitter of the third switch tube SN3 and the collector of the fourth switch tube SN4 are connected to form a second bridge arm, and the sub-module capacitor C N is connected in parallel across the first bridge arm and the second bridge arm; the midpoint of the first bridge arm and the second bridge arm serves as an output port of the full-bridge sub-module.

[0012] Further, the thyristor commutation circuit comprises a third thyristor S3, a fourth thyristor S4, a fifth thyristor S5 and a sixth thyristor S6; wherein the anode of the third thyristor S3 is connected with the anode of the fourth thyristor S4; the cathode of the third thyristor S3 is connected with the upper terminal of the resistive and inductive load and the anode of the fifth thyristor S5; the anode of the sixth thyristor S6 is connected with the lower terminal of the resistive and inductive load and the cathode of the fourth thyristor; and the cathode of the sixth thyristor is connected with the cathode of the fifth thyristor.

[0013] Further, the method comprises a forward current pulse method for generating a pulse with adjustable height, width, rising time and falling time, and a reverse current pulse method for generating a pulse with adjustable height, width, rising time and falling time.

[0014] Further, the control method for generating forward current pulse with adjustable pulse height, width, rising and falling time comprises the following steps:

[0015] Step 1, turn on the third thyristor S3 and the sixth thyristor S6; the lithium battery Buck converter and the super capacitor energy storage full-bridge module valve group are both put into operation, and the modulation ratio of the super capacitor energy storage full-bridge PWM drive signal is selected according to the energy balance criterion in one cycle; the load current is controlled to rise smoothly by controlling the output voltage of the lithium battery Buck converter; when the current is about to reach the platform stage, the super capacitor energy storage full-bridge module valve group is gradually cut off;

[0016] Step 2, the super capacitor energy storage full-bridge module valve group is completely cut off, only the lithium battery Buck converter is put into operation, and the current reaches the platform stage; the load current is maintained constant by controlling the output voltage of the lithium battery Buck converter;

[0017] Step 3, turn off the first Buck switch tube S of the lithium battery Buck converter, cut off the lithium battery Buck converter, and reversely put into the super capacitor energy storage full-bridge; when the load current decreases to zero, turn on the fourth switch tube SN4 in all super capacitor energy storage full-bridge module valve groups, and utilize the first filter inductor L1 in the lithium battery Buck converter and the output capacitor Co to resonate, so that the current of the first filter inductor L1 is 0, the voltage direction of the output capacitor Co resonates from positive to negative to positive to negative, and reaches the maximum value, and then enters the pulse current interval period;

[0018] Alternately performing steps 1-3 can control the circuit structure to generate forward current pulse with adjustable pulse height, width, rising and falling time.

[0019] Further, the control method for generating forward current pulse with adjustable pulse height, width, rising and falling time comprises the following steps:

[0020] Step 1, turn on the fourth thyristor S4 and the fifth thyristor S5; the lithium battery Buck converter and the super capacitor energy storage full-bridge module valve group are both put into operation, and the modulation ratio of the super capacitor energy storage full-bridge PWM drive signal is selected according to the energy balance criterion in one cycle; the load current is controlled to rise smoothly by controlling the output voltage of the lithium battery Buck converter; when the current is about to reach the platform stage, the super capacitor energy storage full-bridge module valve group is gradually cut off;

[0021] Step 2, the super capacitor energy storage full-bridge module valve group is completely cut off, only the lithium battery Buck converter is put into operation, and the current reaches the platform stage; the load current is maintained constant by controlling the output voltage of the lithium battery Buck converter;

[0022] Step 3, turn off the first Buck switch S of the lithium battery Buck converter, cut off the lithium battery Buck converter, and reversely input the super capacitor energy storage full bridge. The load coil energy is recovered to the super capacitor energy storage full bridge module at this stage. When the load current decreases to zero, open the fourth switch SN4 in all super capacitor energy storage full bridge module valve groups, utilize the first filter inductor L1 in the lithium battery Buck converter and the output capacitor Co to resonate, the current of the first filter inductor L1 is 0, the voltage direction of the output capacitor Co resonates from the lower positive to the upper negative, and reaches the maximum value, and then enters the pulse current interval period;

[0023] Alternately performing steps 1-3, the circuit structure can generate a forward current pulse with adjustable pulse height, width, pulse rise and fall time.

[0024] As another aspect of the application, it also relates to an energy feedback type bipolar current pulse generation method. The method controls the thyristor commutation circuit, and controls the output voltage of the lithium battery Buck converter and the super capacitor energy storage full bridge module valve group to generate a specific amplitude and polarity, so as to control the inductive load current pulse waveform. The method controls the modulation ratio of the super capacitor energy storage full bridge module valve group PWM drive signal when reversely inputting, and recovers the inductive load energy by reversely inputting the super capacitor energy storage full bridge, so as to realize the energy balance of the super capacitor in a cycle.

[0025] The application has the following beneficial effects and characteristics:

[0026] 1. The energy feedback type bipolar current pulse generation circuit structure can effectively reduce the voltage stress of the device while realizing a higher output voltage by utilizing the series connection structure of the lithium battery Buck converter and the full bridge sub-module.

[0027] 2. The energy feedback type bipolar current pulse generation circuit structure can provide a larger power for the inductive load in the pulse current rise stage, the lithium battery Buck converter can continuously provide stable energy for the inductive load in the pulse current platform period, and the super capacitor energy storage full bridge can recover the energy released by the inductive load in the pulse current fall stage.

[0028] 3. The energy feedback type bipolar current pulse generation circuit structure can effectively reduce the voltage stress of the device while realizing a higher output voltage, and further obtain a bipolar current pulse with adjustable rise, fall time and amplitude. The super capacitor energy storage full bridge module structure can realize energy recovery when the load current decreases, thereby improving the energy utilization efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1This is a schematic diagram of the circuit topology of a preferred embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of a full-bridge submodule within a supercapacitor full-bridge module valve group according to a preferred embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of the working state of a preferred embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of the voltage and current waveforms across an inductive load according to a preferred embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of the supercapacitor voltage waveform according to a preferred embodiment of the present invention;

[0034] The labels in the diagram represent: 1-Lithium battery Buck converter, 2-Supercapacitor energy storage full-bridge module valve group, and 3-Thyristor commutation circuit. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] like Figure 1 As shown, this invention relates to an energy feedback type bipolar current pulse generation circuit topology, including an input filter capacitor Cin, a first thyristor S1, a second thyristor S2, a lithium battery Buck converter, a supercapacitor energy storage full-bridge module valve group, an output filter capacitor Co, and a thyristor commutation circuit.

[0037] The positive terminal of the input DC bus is connected to the anodes of the first thyristor S1 and the second thyristor S2, and the negative terminal of the input DC bus is connected to the lower terminal of the supercapacitor energy storage full-bridge module; the cathode of the first thyristor S1 is connected to the cathode of the lithium battery. The upper terminal of the output capacitor Co is connected to the right terminal of the first filter inductor L1 of the lithium battery Buck converter and the upper terminal of the thyristor commutation circuit; the lower terminal of the output capacitor Co is connected to the lower terminal of the valve group of the supercapacitor energy storage full-bridge module and the lower terminal of the thyristor commutation circuit.

[0038] The lithium battery Buck converter includes a lithium battery, a first Buck switch S, a first diode D1, and a first filter inductor L1. The supercapacitor energy storage full-bridge module valve group is composed of n full-bridge sub-modules connected in series. The thyristor commutation circuit is composed of a third thyristor S3, a fourth thyristor S4, a fifth thyristor S5, and a sixth thyristor S6.

[0039] like Figure 2 In the full-bridge submodule shown, the emitter of the second switch and the collector of the third switch are connected to form the first bridge arm, and the emitter of the fourth switch and the collector of the fifth switch are connected to form the second bridge arm. The submodule capacitor CN is connected in parallel across the first and second bridge arms. The midpoint between the first and second bridge arms serves as the output port of the full-bridge submodule.

[0040] Corresponding to the above, this invention proposes a basic control method applicable to the energy feedback type bipolar current pulse generation circuit topology described in this invention. This method can control the output of the required bipolar current pulse while maintaining the stability of the supercapacitor voltage during operation. Taking the process of generating a positive pulse current as an example, the waveforms of the load current and load voltage are shown below. Figure 3 As shown. The following will combine... Figure 3 A detailed analysis of the overall work status was conducted.

[0041] Step 1, as follows Figure 3 As shown in stage 1, the third thyristor S3 and the sixth thyristor S6 are turned on. Both the lithium battery and the supercapacitor are put into operation, and the modulation ratio of the supercapacitor energy storage full-bridge PWM drive signal is selected according to the energy balance criterion within one cycle. The load current is controlled to rise smoothly by controlling the output voltage of the lithium battery Buck converter. When the current is about to reach the plateau stage, the supercapacitor energy storage full-bridge module is gradually disconnected.

[0042] Step 2, as follows Figure 3 As shown in stage 2, the supercapacitor is completely switched off, and only the lithium battery is in operation, with the current reaching a plateau. The load current is maintained constant by controlling the output voltage of the lithium battery Buck converter.

[0043] Step 3, as follows Figure 3 As shown in stage 3, the first Buck switch S of the lithium battery Buck converter is turned off, disconnecting the lithium battery and reversing it into the supercapacitor energy storage full bridge. Energy from the load coil is recovered to the supercapacitor during this stage. When the load current drops to zero, the fourth switch in the supercapacitor energy storage full bridge module is turned on. The first filter inductor L1 in the lithium battery Buck converter resonates with the output capacitor Co until the current in the first filter inductor L1 reaches zero. The voltage direction of the output capacitor Co resonates from bottom positive and top negative to top positive and bottom negative, reaching its maximum value, and then enters the pulse current interval period.

[0044] By alternately executing steps 1-3, the topology can be controlled to generate positive current pulses with adjustable pulse height, width, rise time, and fall time.

[0045] If step 1 is modified to open the fourth thyristor S4 and the fifth thyristor S5, and steps 1-3 are alternately executed, the topology can be controlled to generate a reverse current pulse with adjustable pulse height, width, pulse rise and fall time.

[0046] As shown in Figure 4 The simulation waveform of the voltage and current across the inductive load of the energy feedback type bipolar current pulse generation circuit proposed by the application is shown in

[0047] As shown in Figure 5 The simulation waveform of the supercapacitor voltage of the full-bridge sub-module in the supercapacitor energy storage full-bridge module valve group of the energy feedback type bipolar current pulse generation circuit proposed by the application is shown in On the basis of alternately executing steps 1-3, the traditional voltage equalization closed-loop control strategy is added, and the equalization and stability of the supercapacitor voltage of the full-bridge sub-module in the supercapacitor energy storage full-bridge module valve group can be realized.

[0048] The application proposes an energy feedback type bipolar current pulse generation circuit. The energy feedback type bipolar current pulse generation circuit in the application can effectively reduce the device voltage stress while realizing a higher output voltage by using the structure of series connection of the lithium battery Buck converter and the full-bridge sub-module. In the pulse current rise stage, the supercapacitor energy storage full-bridge can provide larger power for the inductive load charging; in the pulse current platform period, the lithium battery Buck converter can continuously provide stable energy for the inductive load; in the pulse current drop stage, the supercapacitor energy storage full-bridge can recover the energy released by the inductive load.

[0049] The basic principles, main features and advantages of the application are shown and described above. It should be understood by those skilled in the art that the application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application.

[0050] The basic principles, main features and advantages of the application are shown and described above. It should be understood by those skilled in the art that the application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application.

Claims

1. A bipolar current pulse generation circuit structure with energy feedback, characterized in that... Including input filter capacitors Cin, first thyristor S1, second thyristor S2, lithium battery Buck converter, supercapacitor energy storage full bridge module, output filter capacitor Co and thyristor commutation circuit; The positive terminal of the input DC bus is connected to the anodes of the first thyristor S1 and the second thyristor S2, and the negative terminal of the input DC bus is connected to the lower terminal of the supercapacitor energy storage full-bridge module. The cathode of the first thyristor S1 is connected to the cathode of the lithium battery in the lithium battery Buck converter. The upper terminal of the output capacitor Co is connected to the right terminal of the first filter inductor L1 of the lithium battery Buck converter and the upper terminal of the thyristor commutation circuit. The lower terminal of the output capacitor Co is connected to the lower terminal of the valve group of the supercapacitor energy storage full-bridge module and the lower terminal of the thyristor commutation circuit. The lithium battery Buck converter includes a lithium battery A, a first Buck switch S, a first diode D1, and a first filter inductor L1. The anode of the lithium battery A is connected to the emitter of the first Buck switch S, and the cathode of the lithium battery is connected to the anode of the first diode D1. The collector of the first Buck switch S is connected to the cathode of the first diode D1 and the left terminal of the first filter inductor L1.

2. The energy feedback type bipolar current pulse generation circuit structure according to claim 1, characterized in that... The supercapacitor energy storage full-bridge module valve group is composed of n full-bridge sub-modules connected in series, where n is a positive integer greater than or equal to 3.

3. The energy feedback type bipolar current pulse generation circuit structure according to claim 2, characterized in that... The full-bridge submodule includes a first switch SN1, a second switch SN2, a third switch SN3, a fourth switch SN4, and a submodule capacitor CN. The emitter of the first switch SN1 is connected to the collector of the second switch SN2 to form a first bridge arm, and the emitter of the third switch SN3 is connected to the collector of the fourth switch SN4 to form a second bridge arm. The submodule capacitor CN is connected in parallel across the first and second bridge arms. The midpoint between the first and second bridge arms serves as the output port of the full-bridge submodule.

4. The energy feedback type bipolar current pulse generation circuit structure according to claim 3, characterized in that, The thyristor commutation circuit includes a third thyristor S3, a fourth thyristor S4, a fifth thyristor S5, and a sixth thyristor S6; wherein, the anode of the third thyristor S3 is connected to the anode of the fourth thyristor S4; the cathode of the third thyristor S3 is connected to the upper terminal of the resistive-inductive load and the anode of the fifth thyristor S5; the anode of the sixth thyristor S6 is connected to the lower terminal of the resistive-inductive load and the cathode of the fourth thyristor; and the cathode of the sixth thyristor is connected to the cathode of the fifth thyristor.

5. The current pulse generation method of the energy feedback type bipolar current pulse generation circuit structure according to claim 4, characterized in that, This includes a method for generating positive current pulses with adjustable pulse height and width, and adjustable pulse rise and fall times, as well as a method for generating reverse current pulses with adjustable pulse height and width, and adjustable pulse rise and fall times.

6. The current pulse generation method of the energy feedback type bipolar current pulse generation circuit structure according to claim 5, characterized in that, The method for controlling the generation of a positive current pulse with adjustable pulse height, width, rise time, and fall time includes the following steps: Step 1: Turn on the third thyristor S3 and the sixth thyristor S6; both the lithium battery Buck converter and the supercapacitor energy storage full-bridge module valve group are put into operation, and the modulation ratio of the supercapacitor energy storage full-bridge PWM drive signal is selected according to the energy balance criterion within one cycle; the load current is controlled to rise steadily by controlling the output voltage of the lithium battery Buck converter; when the current is about to reach the plateau stage, the supercapacitor energy storage full-bridge module valve group is gradually disconnected. Step 2: The valve group of the supercapacitor energy storage full-bridge module is completely disconnected, and only the lithium battery Buck converter is put into operation, and the current reaches the plateau stage; the load current is kept constant by controlling the output voltage of the lithium battery Buck converter. Step 3: Turn off the first Buck switch S of the lithium battery Buck converter, disconnect the lithium battery Buck converter, and reverse it to the supercapacitor energy storage full bridge. The load coil energy is recovered to the supercapacitor energy storage full bridge module at this stage. When the load power After the current drop reaches zero, the fourth switching transistor SN4 in all supercapacitor energy storage full-bridge module valve groups is opened, utilizing the lithium battery Buck converter. The first filter inductor L1 in the converter resonates with the output capacitor Co. When the current of the first filter inductor L1 is 0, the voltage direction of the output capacitor Co resonates from bottom positive and top negative to top positive and bottom negative, and reaches its maximum value. Then it enters the pulse current interval period. By alternately executing steps 1-3, the circuit structure can be controlled to generate positive current pulses with adjustable pulse height, width, rise time, and fall time.

7. The current pulse generation method of the energy feedback type bipolar current pulse generation circuit structure according to claim 5, characterized in that, The method for controlling the generation of reverse current pulses with adjustable pulse height, width, rise time, and fall time includes the following steps: Step 1: Turn on the fourth thyristor S4 and the fifth thyristor S5; both the lithium battery Buck converter and the supercapacitor energy storage full-bridge module valve group are put into operation, and the modulation ratio of the supercapacitor energy storage full-bridge PWM drive signal is selected according to the energy balance criterion within one cycle; the load current is controlled to rise steadily by controlling the output voltage of the lithium battery Buck converter; when the current is about to reach the plateau stage, the supercapacitor energy storage full-bridge module valve group is gradually disconnected. Step 2: The valve group of the supercapacitor energy storage full-bridge module is completely disconnected, and only the lithium battery Buck converter is put into operation, and the current reaches the plateau stage; the load current is kept constant by controlling the output voltage of the lithium battery Buck converter. Step 3: Turn off the first Buck switch S of the lithium battery Buck converter, disconnect the lithium battery Buck converter, and reverse it to the supercapacitor energy storage full bridge. The load coil energy is recovered to the supercapacitor energy storage full bridge module at this stage. When the load current drops to zero, the fourth switch SN4 in all the supercapacitor energy storage full-bridge module valve groups is turned on. The first filter inductor L1 in the lithium battery Buck converter resonates with the output capacitor Co until the current of the first filter inductor L1 is 0. The voltage direction of the output capacitor Co resonates from bottom positive and top negative to top positive and bottom negative, and reaches its maximum value. Then it enters the pulse current interval period. By alternately executing steps 1-3, the circuit structure can be controlled to generate positive current pulses with adjustable pulse height, width, rise time, and fall time.

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