Dual-input dual-mode DC-DC converter

Abstract

The utility model discloses a dual-input dual-mode DC-DC converter, which relates to the technical field of power electronics and comprises an input DC voltage source DC1, an input DC voltage source DC2, a switching tube S1, a switching tube S2, a switching tube S3, a switching tube S4, a switching tube S5, a transformer TX1, an input inductor L1, a diode D1, a diode D2, a diode D3, a diode D4, an output capacitor Co and a load resistor Ro. The direct current-direct current converter solves the problems that when two direct current input voltages of an existing direct current-direct current converter are large in difference, the converter structure is complex, the power density is low, and the efficiency is reduced.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a dual-input dual-mode DC-DC converter. Background Technology

[0002] Combining new energy sources such as fuel cells with traditional batteries is a common application approach. When new energy sources like fuel cells are available, they are prioritized for power supply; otherwise, traditional batteries provide power. This ensures both full utilization of new energy sources and stability of the system output. This creates a demand for DC-DC converters with dual DC inputs.

[0003] When the voltage generated by the fuel cell is close to that of a conventional battery, a switching switch can be used to allow the two DC inputs to be switched into a single DC-DC converter as needed. This requires only one DC-DC converter and one switching switch, resulting in a simple circuit structure and high power density.

[0004] However, when the voltage generated by the fuel cell differs significantly from that of a traditional battery, and a single DC-DC converter cannot meet the conversion requirements of dual inputs, a more complex solution is needed. This dual-DC-input DC-DC converter topology typically has two solutions. One solution connects the fuel cell and battery to separate independent DC-DC converters, with their output voltages Uo connected together. The advantage of this method is high utilization efficiency for both DC input power sources, but the disadvantages are increased device complexity and lower power density. The other solution converts the voltage generated by the fuel cell to the battery voltage via a pre-stage DC-DC converter, and then the battery voltage is converted to the output voltage Uo via a post-stage DC-DC converter. This method has a higher power density than the first solution because the pre-stage DC-DC converter can usually be non-isolated, but the disadvantage is that the fuel cell's output power passes through two stages of DC-DC converters, resulting in reduced efficiency. Utility Model Content

[0005] To address the aforementioned shortcomings in the existing technology, this utility model provides a dual-input dual-mode DC-DC converter that solves the problems of complex converter structure, low power density, and reduced efficiency in existing DC-DC converters when the two DC input voltages differ significantly.

[0006] To achieve the aforementioned objectives, the present invention employs the following technical solution: a dual-input dual-mode DC-DC converter, comprising an input DC voltage source DC1, an input DC voltage source DC2, switching transistors S1, S2, S3, S4, and S5, a transformer TX1, and an input inductor L1. The upper end of the primary winding of the transformer TX1 is connected to the emitter of switching transistor S3 and the collector of switching transistor S4, respectively. The middle tap of the primary winding of the transformer TX1 is connected to the emitter of switching transistor S5. The lower end of the primary winding of the transformer TX1 is connected to the emitter of switching transistor S1 and the collector of switching transistor S2, respectively. The collectors of switching transistors S1 and S3 are both connected to the positive terminal of the input DC voltage source DC1. The emitter of switching transistor S2 and the input inductor L1 are connected to the positive terminal of the input DC voltage source DC1. The emitter of transistor S4 is connected to one end of input inductor L1. The collector of switching transistor S5 is connected to the positive terminal of input DC voltage source DC2. The negative terminals of input DC voltage source DC2, input DC voltage source DC1, and the other end of input inductor L1 are all grounded. The upper end of the secondary winding of transformer TX1 is connected to the anode of diode D1 and the cathode of diode D2, respectively. The lower end of the secondary winding of transformer TX1 is connected to the anode of diode D3 and the cathode of diode D4, respectively. The cathodes of diodes D1 and D3 are both connected to the positive terminal of output capacitor Co. The anodes of diodes D2 and D4, and the negative terminal of output capacitor Co are all grounded. The positive terminal of output capacitor Co is connected to one end of load resistor Ro, and the other end of load resistor Ro is grounded.

[0007] The beneficial effects of the above solution are: This utility model realizes voltage conversion of dual input power supply using a single circuit, power devices are reused, circuit density is improved, and it is suitable for DC-DC converters with two different voltage levels of DC input sources. It solves the problems of complex converter structure, low power density and reduced efficiency in existing DC-DC converters when the two DC input voltages differ significantly.

[0008] Furthermore, the input DC voltage source DC1 is provided through a photovoltaic panel, fuel cell, or battery.

[0009] The beneficial effect of the above-mentioned further solutions is that, through the above technical solutions, photovoltaic panels, fuel cells or batteries can be used to provide the input DC voltage source DC1.

[0010] Furthermore, the input DC voltage source DC2 is provided through a photovoltaic panel, fuel cell, or battery.

[0011] The beneficial effect of the above-mentioned further solutions is that, through the above technical solutions, photovoltaic panels, fuel cells or batteries can be used to provide the input DC voltage source DC2.

[0012] Furthermore, the number of turns at the upper end and the number of turns at the lower end of the primary winding of transformer TX1 are the same.

[0013] The beneficial effect of the above-mentioned further solution is that by setting the same number of turns at the upper and lower ends of the primary winding of transformer TX1, it is conducive to the overall implementation of this solution. Attached Figure Description

[0014] Figure 1 This is a structural diagram of a dual-input dual-mode DC-DC converter.

[0015] Figure 2 This is a structural diagram of an implementation example of a dual-input dual-mode DC-DC converter. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] like Figure 1 As shown, a dual-input dual-mode DC-DC converter includes an input DC voltage source DC1, an input DC voltage source DC2, switching transistors S1, S2, S3, S4, and S5, a transformer TX1, and an input inductor L1. The upper end of the primary winding of the transformer TX1 is connected to the emitter of the switching transistor S3 and the collector of the switching transistor S4, respectively. The middle tap of the primary winding of the transformer TX1 is connected to the emitter of the switching transistor S5. The lower end of the primary winding of the transformer TX1 is connected to the emitter of the switching transistor S1 and the collector of the switching transistor S2, respectively. The collectors of the switching transistors S1 and S3 are both connected to the positive terminal of the input DC voltage source DC1. The emitters of the switching transistors S2 and S4 are both connected to the input DC voltage source L1. One end of inductor L1 is connected to the positive terminal of the input DC voltage source DC2. The negative terminals of the input DC voltage source DC2, DC1, and inductor L1 are all grounded. The upper end of the secondary winding of transformer TX1 is connected to the anode of diode D1 and the cathode of diode D2, respectively. The lower end of the secondary winding of transformer TX1 is connected to the anode of diode D3 and the cathode of diode D4, respectively. The cathodes of diodes D1 and D3 are both connected to the positive terminal of output capacitor Co. The anodes of diodes D2 and D4, and the negative terminal of output capacitor Co are all grounded. The positive terminal of output capacitor Co is connected to one end of load resistor Ro, and the other end of load resistor Ro is grounded.

[0018] The input DC voltage source DC1 is provided through a photovoltaic panel, fuel cell, or battery.

[0019] The input DC voltage source DC2 is provided through a photovoltaic panel, fuel cell, or battery.

[0020] The number of turns at the upper end and the number of turns at the lower end of the primary winding of transformer TX1 are the same.

[0021] In one embodiment of this utility model, a fuel cell is used as an input DC voltage source DC1, and a parallel capacitor C1 is provided on the output side of the fuel cell; simultaneously, a storage battery is used as an input DC voltage source DC2, and a parallel capacitor C2 is provided on its output side, as follows. Figure 2 As shown.

[0022] In this embodiment, the fuel cell, parallel capacitor C1, input inductor L1, switching transistors S1, S2, S3, S4, and S5, transformer TX1, rectifier bridge composed of diodes D1-D4, and output capacitor Co constitute a current-fed full-bridge DC-DC converter.

[0023] When switch S5 is turned on, the battery, parallel capacitor C2, input inductor L1, switch S2, switch S4, transformer TX1, rectifier bridge composed of diodes D1-D4, and output capacitor Co constitute a current-fed push-pull DC-DC converter.

[0024] As can be seen, the current-fed full-bridge DC-DC converter and the current-fed push-pull DC-DC converter mentioned above share most of the components, thus improving the power density.

[0025] This invention provides a dual-input dual-mode DC-DC converter, suitable for applications where the two DC input voltages differ significantly. This invention utilizes a single circuit to achieve voltage conversion for dual input power supplies, and multiplexes power devices in two operating modes (current-fed full-bridge DC-DC converter mode and current-fed push-pull DC-DC converter mode), thereby improving the power density of the circuit.

[0026] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of this invention, and should be understood that the scope of protection of this invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on these technical teachings disclosed in this invention without departing from the essence of this invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A dual-input dual-mode DC-DC converter, characterized in that: It includes an input DC voltage source DC1, an input DC voltage source DC2, a switch tube S1, a switch tube S2, a switch tube S3, a switch tube S4, a switch tube S5, a transformer TX1 and an input inductor L1, wherein the upper end of the primary winding of the transformer TX1 is respectively connected to the emitter of the switch tube S3 and the collector of the switch tube S4, the middle tap of the primary winding of the transformer TX1 is connected to the emitter of the switch tube S5, the lower end of the primary winding of the transformer TX1 is respectively connected to the emitter of the switch tube S1 and the collector of the switch tube S2, the collector of the switch tube S1 and the collector of the switch tube S3 are both connected to the positive electrode of the input DC voltage source DC1, the emitter of the switch tube S2 and the emitter of the switch tube S4 are both connected to one end of the input inductor L1, The collector of the switch tube S5 is connected to the positive electrode of the input DC voltage source DC2, the negative electrode of the input DC voltage source DC2, the negative electrode of the input DC voltage source DC1 and the other end of the input inductor L1 are all grounded, the upper end of the secondary winding of the transformer TX1 is respectively connected to the anode of the diode D1 and the cathode of the diode D2, the lower end of the secondary winding of the transformer TX1 is respectively connected to the anode of the diode D3 and the cathode of the diode D4, the cathode of the diode D1 and the cathode of the diode D3 are both connected to the positive electrode of the output capacitor Co, the anode of the diode D2, the anode of the diode D4 and the negative electrode of the output capacitor Co are all grounded, the positive electrode of the output capacitor Co is connected to one end of the load resistor Ro, and the other end of the load resistor Ro is grounded.

2. The dual-input dual-mode DC-DC converter according to claim 1, characterized in that: The input DC voltage source DC1 is provided by a photovoltaic panel, a fuel cell or a battery.

3. The dual-input dual-mode DC-DC converter according to claim 1, characterized in that: The input DC voltage source DC2 is provided by a photovoltaic panel, a fuel cell or a battery.

4. The dual-input dual-mode DC-DC converter according to claim 1, characterized in that: The number of turns at the upper end and the number of turns at the lower end of the primary winding of the transformer TX1 are the same.

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