DCDC isolation circuit

Abstract

The invention discloses a DCDC isolation circuit, and relates to the technical field of power isolation output, and the DCDC isolation circuit comprises a power input module, a first switch piece, a second switch piece, a switch control module, a primary energy storage module, a first output isolation module, a second output isolation module, a secondary energy storage module, and a load output module. According to the invention, the first and second switch pieces synchronously controlled by the switch control module are matched with the primary energy storage module, the secondary energy storage module, the first output isolation module and the second output isolation module which have specific polarities and cut-off directions, so that electrical isolation between an input side and a load side is respectively realized under the switch-on state and the switch-off state of the switch; voltage fluctuation, interference or faults of the input side are effectively prevented from being directly conducted to the load side, and safe operation of a load circuit is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power isolation output, in particular to a DCDC isolation circuit. BACKGROUND

[0002] With the increasing demand for direct current power conversion of electronic devices, DC-DC conversion circuits are widely used in various power electronic systems. In practical applications, many occasions not only need to realize the conversion of direct current voltage, but also hope that the input end and the output end have certain electrical isolation capability to avoid the direct influence of voltage fluctuation, electromagnetic interference or fault on the safe operation of the load side circuit.

[0003] In related technologies, there is a direct electrical connection between the input and output of the non-isolated DC-DC converter, which cannot meet the isolation requirement, and the isolated DC-DC circuit based on transformer has complex structure, large number of devices and large volume. Therefore, there is an urgent need for a direct current voltage conversion scheme with simple structure, easy implementation and certain isolation characteristics. SUMMARY

[0004] The main purpose of the present application is to provide a DCDC isolation circuit, which aims to solve the technical problems of complex structure and large volume of the isolated DC-DC circuit in related technologies.

[0005] To achieve the above purpose, the present application provides a DCDC isolation circuit, which comprises a power input module, a first switch, a second switch, a switch control module, a primary energy storage module, a first output isolation module, a second output isolation module, a secondary energy storage module and a load output module, wherein: The positive electrode of the power input module is connected with the input end of the first switch, the output end of the first switch is connected with one end of the primary energy storage module, one end of the primary energy storage module is also connected with one end of the first output isolation module, the other end of the first output isolation module is connected with one end of the secondary energy storage module, the other end of the secondary energy storage module is connected with one end of the second output isolation module, the other end of the second output isolation module is connected with the other end of the primary energy storage module and the output end of the second switch respectively, the input end of the second switch is connected with the negative electrode of the power input module, and the control end of the first switch and the control end of the second switch are connected with the switch control module; wherein, The charging polarity of the first energy storage module is opposite to the discharging polarity, the charging polarity of the second energy storage module is the same as the discharging polarity, the cutoff direction of the first output isolation module is from one end to the other end of the first output isolation module, and the cutoff direction of the second output isolation module is from one end to the other end of the second output isolation module.

[0006] In one embodiment, the first and second switching elements are controlled by the switch control module to be either turned on or off. The first output isolation module and the second output isolation module are used to isolate the power input module from supplying power to the load when the first switch and the second switch are turned on. The first output isolation module and the second output isolation module are also used to isolate the secondary energy storage module from supplying power to the input terminal in reverse when the first switch and the second switch are turned off.

[0007] In one embodiment, the primary energy storage module includes an energy storage inductor. One end of the energy storage inductor is connected to the output terminal of the first switching device and one end of the first output isolation module, respectively, and the other end of the energy storage inductor is connected to the output terminal of the second switching device and the other end of the second output isolation module, respectively.

[0008] In one embodiment, the secondary energy storage module includes an electrolytic capacitor; The positive terminal of the electrolytic capacitor is connected to one end of the second output isolation module, and the negative terminal of the electrolytic capacitor is connected to the other end of the first output isolation module.

[0009] In one embodiment, the first output isolation module includes a first diode, and the second output isolation module includes a second diode; wherein, The anode of the first diode is connected to the cathode of the electrolytic capacitor, and the cathode of the first diode is connected to one end of the energy storage inductor and the output terminal of the first switching device, respectively. The anode of the second diode is connected to the other end of the energy storage inductor and the output terminal of the second switch, respectively, and the cathode of the second diode is connected to the negative terminal of the electrolytic capacitor.

[0010] One or more technical solutions proposed in this application have at least the following technical effects: This application utilizes first and second switching devices synchronously controlled by a switching control module, in conjunction with a primary energy storage module, a secondary energy storage module, and first and second output isolation modules with specific polarity and cutoff direction settings. This achieves electrical isolation between the input side and the load side in both the on and off states of the switch, effectively preventing voltage fluctuations, interference, or faults on the input side from being directly conducted to the load side, thus ensuring the safe operation of the load circuit. Simultaneously, this application primarily uses basic components such as inductors, capacitors, diodes, and switching transistors, simplifying the circuit structure and reducing implementation cost and size. This results in a smaller number of components, a more compact structure, and easier implementation and control of the entire conversion circuit. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0012] Figure 1 This is a circuit connection diagram of one embodiment of the DC-DC isolation circuit of this application.

[0013] The implementation, functional features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0014] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0015] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0016] To address the aforementioned problems, this application provides a DC-DC isolation circuit, the specific embodiments and implementation methods of which are as follows: In this embodiment, the DC-DC isolation circuit includes a power input module, a first switching element, a second switching element, a switch control module, a primary energy storage module, a first output isolation module, a second output isolation module, a secondary energy storage module, and a load output module, wherein: The positive terminal of the power input module is connected to the input terminal of the first switching element. The output terminal of the first switching element is connected to one end of the primary energy storage module. One end of the primary energy storage module is also connected to one end of the first output isolation module. The other end of the first output isolation module is connected to one end of the secondary energy storage module. The other end of the secondary energy storage module is connected to one end of the second output isolation module. The other end of the second output isolation module is connected to both the other end of the primary energy storage module and the output terminal of the second switching element. The input terminal of the second switching element is connected to the negative terminal of the power input module. The control terminals of both the first and second switching elements are connected to the switch control module. The charging polarity of the first energy storage module is opposite to that of the discharging polarity, and the charging polarity of the second energy storage module is the same as that of the discharging polarity. The cutoff direction of the first output isolation module is from one end to the other, and the cutoff direction of the second output isolation module is from one end to the other.

[0017] The first and second switching components are controlled by the switch control module to be either turned on or off. The first output isolation module and the second output isolation module are used to isolate the power input module from supplying power to the load when the first switch and the second switch are turned on. The first output isolation module and the second output isolation module are also used to isolate the secondary energy storage module from supplying power to the input terminal in reverse when the first switch and the second switch are turned off.

[0018] Specifically, in this embodiment, the positive terminal of the power input module is connected to the input terminal of the first switch, the output terminal of the first switch is connected to one end of the primary energy storage module, and one end of the primary energy storage module is also connected to one end of the first output isolation module. When the first switch is turned on, the electrical energy of the power input module can directly act on the primary energy storage module through the first switch, enabling the primary energy storage module to complete the charging and energy storage process. At the same time, since one end of the primary energy storage module is also connected to one end of the first output isolation module, the first output isolation module is in a cut-off state during the period when the first switch is turned on, thereby ensuring that the electrical energy of the power input module does not directly enter the secondary energy storage module or the load terminal, achieving electrical isolation between the input side and the output side.

[0019] The other end of the first output isolation module is connected to one end of the secondary energy storage module, and the other end of the secondary energy storage module is connected to one end of the second output isolation module. The other end of the second output isolation module is connected to the other end of the primary energy storage module and the output terminal of the second switch. The input terminal of the second switch is connected to the negative terminal of the power input module. This structure forms a complete energy transfer loop: when the first and second switches are disconnected, the energy stored in the primary energy storage module can be unidirectionally transferred to the secondary energy storage module through the second output isolation module. Simultaneously, the second output isolation module ensures that the secondary energy storage module will not reverse charge, ultimately forming a unidirectional power supply path from the secondary energy storage module to the load. During this stage, the power input module and the output side remain electrically isolated, thus achieving indirect energy transfer.

[0020] Both the control terminals of the first and second switching devices are connected to the switch control module, and both devices are under the unified control of the same module during operation. The switch control module generates synchronous control signals to enable the first and second switching devices to turn on or off synchronously. When both devices are on, the power input module charges only the primary energy storage module, and due to the cutoff effect of the first output isolation module, energy does not flow directly from the input to the output. When both devices are off, the energy in the primary energy storage module is released and transferred to the secondary energy storage module through the second output isolation module, thus supplying power to the load, thereby achieving decoupling between input and output in the time dimension. To achieve this effect, the charging polarity and discharging polarity of the first energy storage module must be opposite; that is, an electromotive force opposite to that generated during the energy release phase is generated during the charging phase, driving energy to be transferred to the output side through the second module. The charging polarity and discharging polarity of the second energy storage module are the same, indicating that this module mainly plays the role of energy buffering and filtering. Its polarity remains consistent during charging and discharging, making it suitable for use with capacitor-type energy storage elements to stabilize the output voltage and reduce ripple.

[0021] The cutoff direction of the first output isolation module is from one end to the other, and the cutoff direction of the second output isolation module is from one end to the other. This directional description indicates that both output isolation modules are devices with unidirectional conduction characteristics, used to establish unidirectional energy flow paths at different operating stages. During the switching phase, both the first and second output isolation modules are in a reverse cutoff state, used to isolate the power input module from supplying power to the load; during the switching phase, both output isolation modules conduct in the set direction, thereby allowing unidirectional energy transfer between the primary and secondary energy storage modules, and between the secondary energy storage module and the load.

[0022] In summary, the combined function of the first output isolation module and the second output isolation module is as follows: on the one hand, when the first and second switches are turned on, the direct electrical path between the power input module and the load is completely cut off, avoiding direct power supply from the input power source to the load; on the other hand, when the first and second switches are turned off, the energy in the secondary energy storage module is prevented from being fed back to the power input module, thereby ensuring that energy can only be transferred along the unidirectional path of "power input module → primary energy storage module → secondary energy storage module → load", achieving functional isolation and safe decoupling between the input and output ends.

[0023] Through the combination of the above structure and working mechanism, this solution realizes a two-stage energy transfer structure based on a primary energy storage module and a secondary energy storage module. Without using transformer isolation, the timing control of the switch control module and the unidirectional conduction characteristics of the first and second output isolation modules ensure that there is no direct electrical connection path between the power input module and the load at any time. Thus, while ensuring a simple structure, low cost, and small size, it achieves indirect energy transfer between input and output and effective electrical isolation.

[0024] In one feasible embodiment, the primary energy storage module includes an energy storage inductor, one end of which is connected to the output terminal of a first switching device and one end of a first output isolation module, and the other end of which is connected to the output terminal of a second switching device and the other end of a second output isolation module. The secondary energy storage module includes an electrolytic capacitor. The positive terminal of the electrolytic capacitor is connected to one end of the second output isolation module, and the negative terminal of the electrolytic capacitor is connected to the other end of the first output isolation module. The first output isolation module includes a first diode, and the second output isolation module includes a second diode; wherein, The anode of the first diode is connected to the cathode of the electrolytic capacitor, and the cathode of the first diode is connected to one end of the energy storage inductor and the output terminal of the first switching device, respectively. The anode of the second diode is connected to the other end of the energy storage inductor and the output terminal of the second switch, respectively, and the cathode of the second diode is connected to the negative terminal of the electrolytic capacitor.

[0025] Specifically, refer to Figure 1 In this embodiment, the positive terminal of the power input module is connected to one end of the energy storage inductor L1 via the first switch S1. One end of the energy storage inductor L1 is connected to the cathode of the first diode D1. The anode of the first diode D1 is connected to the negative terminal of the electrolytic capacitor C1. The negative terminal of the power input module is connected to the other end of the energy storage inductor L1 via the second switch S2. The other end of the energy storage inductor L1 is connected to the anode of the second diode D2. The cathode of the second diode D2 is connected to the positive terminal of the electrolytic capacitor.

[0026] In this embodiment, each functional module is implemented using specific devices. The primary energy storage module uses an energy storage inductor L1, the secondary energy storage module uses an electrolytic capacitor C1, and the first and second output isolation modules are implemented using a first diode D1 and a second diode D2, respectively. The energy storage inductor L1 is located between the first switch S1 and the second switch S2, serving as the core energy storage and conversion unit of the entire circuit. When the switches are activated, the energy storage inductor, based on its own characteristics, can alternately charge and discharge with opposite polarities, thereby achieving the time-sequential transfer of energy between the input and output terminals. The first switch S1 and the second switch S2 can be power semiconductor switches, such as IGBTs.

[0027] Electrolytic capacitor C1, as a secondary energy storage module, is mainly used to receive energy released from energy storage inductor L1 and to stabilize and filter the output voltage. Since the charging polarity and discharging polarity of the electrolytic capacitor are the same, it can maintain a stable DC voltage output throughout the entire operation process, while smoothing the pulse energy from the energy storage inductor, thereby providing a relatively stable power supply to the load.

[0028] The first diode D1 and the second diode D2 form two unidirectional conduction paths to control the energy flow at different operating stages. When the first and second switching devices are on, due to the cutoff characteristics of the diodes, the power input module cannot directly supply power to the electrolytic capacitor through the diodes. When the switching devices are off, the diodes conduct in the set direction, allowing the energy in the energy storage inductor to be transferred unidirectionally to the electrolytic capacitor, thereby realizing energy release and power output. This also ensures that the voltage of the electrolytic capacitor will not recharge the energy storage inductor, and due to the effect of D2, there is no conduction path between the electrolytic capacitor C1 and the input terminal.

[0029] This implementation achieves functional isolation between input and output, indirect energy transfer, and stable DC output without using transformer isolation. It also has the advantages of simple structure, few components, low cost, and ease of implementation.

[0030] The above are merely preferred embodiments of this application and do not limit the scope of the patent application. Any equivalent structural transformations made based on the inventive concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of this application.

Claims

1. A DC-DC isolation circuit, characterized in that, The DC-DC isolation circuit includes a power input module, a first switching element, a second switching element, a switch control module, a primary energy storage module, a first output isolation module, a second output isolation module, a secondary energy storage module, and a load output module, wherein: The positive terminal of the power input module is connected to the input terminal of the first switch. The output terminal of the first switch is connected to one end of the primary energy storage module. One end of the primary energy storage module is also connected to one end of the first output isolation module. The other end of the first output isolation module is connected to one end of the secondary energy storage module. The other end of the secondary energy storage module is connected to one end of the second output isolation module. The other end of the second output isolation module is connected to both the other end of the primary energy storage module and the output terminal of the second switch. The input terminal of the second switch is connected to the negative terminal of the power input module. The control terminals of both the first and second switches are connected to the switch control module. The charging polarity of the first energy storage module is opposite to that of the discharging polarity, and the charging polarity of the second energy storage module is the same as that of the discharging polarity. The cutoff direction of the first output isolation module is from one end of the first output isolation module to the other end, and the cutoff direction of the second output isolation module is from one end of the second output isolation module to the other end.

2. The DC-DC isolation circuit according to claim 1, characterized in that, The first switch and the second switch are controlled by the switch control module to be either turned on or off. The first output isolation module and the second output isolation module are used to isolate the power input module from supplying power to the load when the first switch and the second switch are turned on. The first output isolation module and the second output isolation module are also used to isolate the secondary energy storage module from supplying power to the input terminal in reverse when the first switch and the second switch are turned off.

3. The DC-DC isolation circuit according to claim 2, characterized in that, The primary energy storage module includes an energy storage inductor. One end of the energy storage inductor is connected to the output terminal of the first switch and one end of the first output isolation module, respectively, and the other end of the energy storage inductor is connected to the output terminal of the second switch and the other end of the second output isolation module, respectively.

4. The DC-DC isolation circuit according to claim 3, characterized in that, The secondary energy storage module includes an electrolytic capacitor; The positive terminal of the electrolytic capacitor is connected to one end of the second output isolation module, and the negative terminal of the electrolytic capacitor is connected to the other end of the first output isolation module.

5. The DC-DC isolation circuit according to claim 4, characterized in that, The first output isolation module includes a first diode, and the second output isolation module includes a second diode; wherein, The anode of the first diode is connected to the cathode of the electrolytic capacitor, and the cathode of the first diode is connected to one end of the energy storage inductor and the output terminal of the first switching device, respectively. The anode of the second diode is connected to the other end of the energy storage inductor and the output terminal of the second switch, respectively, and the cathode of the second diode is connected to the negative terminal of the electrolytic capacitor.

Images