High-power bidirectional isolation circuit

Abstract

The utility model, which relates to the technical field of the converter, provides a high-power bidirectional isolation circuit comprising a main controller, a buck-boost resonance module, an inversion rectification module, and an isolation transformer. The buck-boost resonance module comprises a first buck-boost resonance module and a second buck-boost resonance module; the first step-up and step-down resonance module and the second step-up and step-down resonance module are connected in parallel, then are connected with a hydrogen fuel cell power supply interface and are connected with the inversion rectification module through the isolation transformer, and the other end of the inversion rectification module is connected with a lithium battery power supply interface. And when the reverse power supply and the forward power supply are switched, wrong voltage control is carried out, so that the reversing speed and stability are ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of converters, in particular to a high-power bidirectional isolation circuit. Background Art

[0002] With the continuous update and iteration of bidirectional DCDC converters, bidirectional isolated DCDC converters have been widely used in microgrids, distributed power generation, energy storage systems, rail transit and other fields. Isolated DCDC converters avoid the problem that non-isolated DCDC converters are not safe enough in high-power loops under extreme working conditions.

[0003] In the actual application of new energy such as hydrogen energy, wind energy, photovoltaics, etc., the output power is often unstable and cannot directly supply power to the load, which requires a high-power DCDC converter. In order to power the auxiliary machine of hydrogen energy, the high-power DCDC converter needs to support bidirectional power supply conditions. When switching between working conditions, due to the instability of hydrogen energy itself and the high-power application scenario, the commutation will often be advanced or delayed, resulting in undervoltage or overvoltage problems.

[0004] Therefore, how to solve the above problems and achieve stable switching of high-power bidirectional DCDC converters is of great significance for the development and application of new energy. Utility Model Content

[0005] In order to overcome the deficiencies in the prior art, the utility model provides a high-power bidirectional isolation circuit, which ensures a fast and stable voltage commutation process.

[0006] The technical solution adopted by the utility model to solve its technical problems is: a high-power bidirectional isolation circuit, which is improved in that it includes: a main controller, a buck-boost resonance module, an inverter rectifier module, and an isolation transformer; the buck-boost resonance module includes a first buck-boost resonance module and a second buck-boost resonance module, and the first buck-boost resonance module and the second buck-boost resonance module have the same structure; the first buck-boost resonance module and the second buck-boost resonance module are connected in parallel to the hydrogen fuel cell power interface, and are connected to the inverter rectifier module through the isolation transformer, and the other end of the inverter rectifier module is connected to the lithium battery power interface.

[0007] In the above circuit, the buck-boost resonant module includes a Boost output circuit and an LLC resonant circuit. The Boost output circuit is composed of three identical unit chopper circuits connected in parallel; the LLC resonant circuit is composed of two identical unit full-bridge LLC inverter rectifier circuits connected in series.

[0008] In the above circuit, the Boost output circuit includes a first switch group VT1, a second switch group VT2, and a third switch group VT3. The first switch group VT1 is connected to the positive pole of the first phase hydrogen fuel cell power interface, the second switch group VT2 is connected to the positive pole of the second phase hydrogen fuel cell power interface, and the third switch group VT3 is connected to the positive pole of the third phase hydrogen fuel cell power interface.

[0009] In the above circuit, the LLC resonant circuit includes a fourth switch group VT4, a fifth switch group VT5, a sixth switch group VT6 and a seventh switch group VT7. The lower end of the first switch group VT1, the lower end of the second switch group VT2, the lower end of the third switch group VT3, the lower end of the fourth switch group VT4, the lower end of the fifth switch group VT5, the lower end of the sixth switch group VT6 and the lower end of the seventh switch group VT7 are connected to the negative pole of the hydrogen fuel cell power interface. The fourth switch group VT4 and the fifth switch group VT5 are connected to the isolation transformer 1T5; the sixth switch group VT6 and the seventh switch group VT7 are connected to the isolation transformer 1T6.

[0010] In the above circuit, the inverter rectifier module includes an eighth switch group VT8, a ninth switch group VT9, a tenth switch group VT10, and an eleventh switch group VT11. The eighth switch group VT8 and the ninth switch group VT9 are connected to the isolation transformer 1T5, and the tenth switch group VT10 and the eleventh switch group VT11 are connected to the isolation transformer 1T6. The upper end of the eighth switch group VT8 and the upper end of the ninth switch group VT9 are connected to the positive pole of the lithium battery power interface, and the lower end of the eighth switch group VT8 and the lower end of the ninth switch group VT9 are connected to the upper end of the tenth switch group VT10 and the upper end of the eleventh switch group VT11; the lower ends of the tenth switch group VT10 and the eleventh switch group VT11 are connected to the negative pole of the lithium battery power interface.

[0011] The beneficial effects of the utility model are: two groups of the same buck-boost resonant modules are connected in parallel with the inverter rectifier module to achieve bidirectional current sharing at the hardware level. The inductor current of the Boost output circuit adopts the DCM control method, which is suitable for occasions with large load current changes; the capacitor requirements for the secondary output are relatively low, which is conducive to reducing the capacity and volume of the capacitor. When switching between reverse power supply and forward power supply, the voltage error control is performed through software to ensure fast and stable commutation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A circuit diagram of a Boost output circuit in a buck-boost resonant module provided in an embodiment of the utility model;

[0013] Figure 2 A circuit diagram of an inverter rectifier module is provided for an embodiment of the utility model;

[0014] Figure 3 A circuit diagram of an LLC resonant circuit in a buck-boost resonant module provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0015] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0016] The following will clearly and completely describe the concept, specific structure and technical effects of the utility model in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the utility model. In addition, all the connection / connection relationships involved in the patent do not refer to the direct connection of components, but refer to the formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the creation of the utility model can be combined interchangeably without conflicting with each other.

[0017] The utility model provides a high-power bidirectional isolation circuit, such as Figure 1 As shown, the circuit includes a main controller, a buck-boost resonant module, an inverter rectifier module, and an isolation transformer; the buck-boost resonant module includes a first buck-boost resonant module and a second buck-boost resonant module, and the first buck-boost resonant module and the second buck-boost resonant module have the same structure.

[0018] The present application uses two groups of identical buck-boost resonant modules and an inverter rectifier module in parallel. When switching between reverse power supply and forward power supply, voltage error control is performed through software to ensure fast and stable commutation.

[0019] Among them, the first buck-boost resonant module and the second buck-boost resonant module are connected in parallel to the hydrogen fuel cell power interface, and are connected to the inverter rectifier module through the isolation transformer, and the other end of the inverter rectifier module is connected to the lithium battery power interface.

[0020] In one possible implementation, the buck-boost resonant module includes a first buck-boost resonant module and a second buck-boost resonant module composed of a Boost output circuit and an LLC resonant circuit, wherein the Boost output circuit is composed of three identical unit chopper circuits connected in parallel; and the LLC resonant circuit is composed of two identical unit full-bridge PWM inverter rectifier circuits connected in series.

[0021] In an exemplary embodiment, only the first buck-boost resonance module is used as an example for description. Figure 2As shown, the Boost output circuit includes a first switch group VT1, a second switch group VT2, and a third switch group VT3, the first switch group VT1 is connected to the positive pole of the first phase hydrogen fuel cell power interface, the second switch group VT2 is connected to the positive pole of the second phase hydrogen fuel cell power interface, and the third switch group VT3 is connected to the positive pole of the third phase hydrogen fuel cell power interface.

[0022] The LLC resonant circuit includes a fourth switch group VT4, a fifth switch group VT5, a sixth switch group VT6 and a seventh switch group VT7. The lower end of the first switch group VT1, the lower end of the second switch group VT2, the lower end of the third switch group VT3, the lower end of the fourth switch group VT4, the lower end of the fifth switch group VT5, the lower end of the sixth switch group VT6 and the lower end of the seventh switch group VT7 are connected to the negative pole of the hydrogen fuel cell power interface; the fourth switch group VT4 and the fifth switch group VT5 are connected to the isolation transformer 1T5; the sixth switch group VT6 and the seventh switch group VT7 are connected to the isolation transformer 1T6.

[0023] In a possible implementation, the inverter-rectifier module includes a first inverter-rectifier module and a second inverter-rectifier module. In an exemplary embodiment, only the first inverter-rectifier module is used as an example for description. Figure 1 As shown, the first inverter finishing module includes an eighth switch group VT8, a ninth switch group VT9, a tenth switch group VT10, and an eleventh switch group VT11. The eighth switch group VT8 and the ninth switch group VT9 are connected to the isolation transformer 1T5; the tenth switch group VT10 and the eleventh switch group VT11 are connected to the isolation transformer 1T6.

[0024] The upper end of the eighth switch group VT8 and the upper end of the ninth switch group VT9 are connected to the positive pole of the lithium battery power interface, and the lower end of the eighth switch group VT8 and the lower end of the ninth switch group VT9 are connected to the upper end of the tenth switch group VT10 and the upper end of the eleventh switch group VT11; the lower ends of the tenth switch group VT10 and the eleventh switch group VT11 are connected to the negative pole of the lithium battery power interface.

[0025] When the energy transfer direction is from the hydrogen fuel cell power interface to the lithium battery power interface, the hydrogen fuel cell power interface inputs a DC voltage to the buck-boost resonant module, and the voltage is boosted by the Boost output circuit inside the buck-boost resonant module. The inductor current of the Boost output circuit adopts the DCM control method, which is suitable for occasions with large load current changes; the capacitance requirements for the secondary output are relatively low, which is conducive to reducing the capacity and volume of the capacitor. The main controller sends a PWM pulse start instruction to the slave controller inside the buck-boost resonant module, and the slave controller sends a drive pulse signal. At this time, the buck-boost resonant module is composed of a full-bridge inverter parallel circuit composed of the switch tube inside the IGBT module, and the rectifier circuit composed of the IGBT in the inverter rectifier module and the inverter circuit inside the buck-boost resonant module on the primary side of the isolation transformer form an LLC resonant circuit. The square wave voltage output by the buck-boost resonant module is isolated and transformed. After rectification and output capacitor filtering, the square wave AC voltage outputs a DC1200V~DC1720V voltage to the lithium battery side to power the traction inverter and charge the lithium battery.

[0026] When the direction of energy transfer is from the lithium battery power interface to the hydrogen fuel cell power interface, the lithium battery power interface inputs a DC voltage to the inverter rectifier module, the main controller sends a PWM pulse start instruction to the slave controller inside the inverter rectifier module, and the slave controller sends a drive pulse signal. At this time, the inverter rectifier module is composed of a full-bridge inverter series circuit composed of the switch tube inside the IGBT module. This circuit and the rectifier circuit inside the primary side buck-boost resonant module of the transformer form an LLC resonant circuit. After being stepped down by the buck-boost module inside the buck-boost resonant module, the stepped-down DC voltage is output through the hydrogen fuel cell power interface.

[0027] The utility model connects two groups of identical buck-boost resonant modules in parallel with an inverter rectifier module in different power supply modes, and performs voltage error control through software when switching between reverse power supply and forward power supply to ensure fast and stable commutation.

[0028] The above is a specific description of the preferred implementation of the utility model, but the invention of the utility model is not limited to the described embodiments. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the utility model. These equivalent deformations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A high-power bidirectional isolation circuit, characterized in that: include: A main controller, a buck-boost resonant module, an inverter rectifier module, and an isolation transformer; the buck-boost resonant module includes a first buck-boost resonant module and a second buck-boost resonant module, and the first buck-boost resonant module and the second buck-boost resonant module have the same structure; The first buck-boost resonant module and the second buck-boost resonant module are connected in parallel to the hydrogen fuel cell power interface, and are connected to the inverter rectifier module through the isolation transformer. The other end of the inverter rectifier module is connected to the lithium battery power interface.

2. The high-power bidirectional isolation circuit according to claim 1, characterized in that: The buck-boost resonant module comprises a Boost output circuit and an LLC resonant circuit. The Boost output circuit is composed of three identical unit chopper circuits connected in parallel; the LLC resonant circuit is composed of two identical unit full-bridge PWM inverter rectifier circuits connected in series.

3. The high-power bidirectional isolation circuit according to claim 2, characterized in that: The Boost output circuit includes a first switch group VT1, a second switch group VT2, and a third switch group VT3. The first switch group VT1 is connected to the positive pole of the first phase hydrogen fuel cell power interface, the second switch group VT2 is connected to the positive pole of the second phase hydrogen fuel cell power interface, and the third switch group VT3 is connected to the positive pole of the third phase hydrogen fuel cell power interface.

4. The high-power bidirectional isolation circuit according to claim 3, characterized in that: The LLC resonant circuit includes a fourth switch group VT4, a fifth switch group VT5, a sixth switch group VT6 and a seventh switch group VT7. The lower end of the first switch group VT1, the lower end of the second switch group VT2, the lower end of the third switch group VT3, the lower end of the fourth switch group VT4, the lower end of the fifth switch group VT5, the lower end of the sixth switch group VT6, and the lower end of the seventh switch group VT7 are connected to the negative electrode of the hydrogen fuel cell power interface; The fourth switch group VT4 and the fifth switch group VT5 are connected to the isolation transformer 1T5; the sixth switch group VT6 and the seventh switch group VT7 are connected to the isolation transformer 1T6.

5. The high-power bidirectional isolation circuit according to claim 1, characterized in that: The inverter rectifier module includes an eighth switch group VT8, a ninth switch group VT9, a tenth switch group VT10, and an eleventh switch group VT11. The eighth switch group VT8 and the ninth switch group VT9 are connected to the isolation transformer 1T5; the tenth switch group VT10 and the eleventh switch group VT11 are connected to the isolation transformer 1T6; The upper end of the eighth switch group VT8 and the upper end of the ninth switch group VT9 are connected to the positive pole of the lithium battery power interface, and the lower end of the eighth switch group VT8 and the lower end of the ninth switch group VT9 are connected to the upper end of the tenth switch group VT10 and the upper end of the eleventh switch group VT11; the lower ends of the tenth switch group VT10 and the eleventh switch group VT11 are connected to the negative pole of the lithium battery power interface.

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