Energy storage battery direct current grid-connected system for preventing bus current feedback

Abstract

The invention discloses an energy storage battery direct-current grid-connected system for preventing bus current feedback, relates to a grid-connected power circuit and a grid-connected control circuit, and belongs to the field of direct-current bus voltage regulation and control. The system comprises a control part and a power part, the control part comprises a storage battery voltage isolation sampling unit, a data processing unit, a bus voltage isolation sampling unit and an isolation driving unit; the power part comprises a storage battery unit, a load unit, a power generation unit, an MOS tube unit, an ideal diode unit and a fly-wheel diode unit. Three system states of grid-connected channel closing, trickle charging and grid-connected channel opening are switched by analyzing the magnitude relationship between the storage battery voltage and the bus voltage in real time, the storage battery is prevented from being damaged by impact current, the long-term floating charging performance is prevented from being reduced, meanwhile, the bus energy is fully utilized, and the system reliability is improved. The method is especially suitable for a system which takes generator power supply as a main power supply and storage battery emergency power supply as an auxiliary power supply and has inductive load on a bus.

Description

Technical Field

[0001] This invention discloses a DC grid-connected energy storage battery system for preventing bus current feedback, which relates to energy storage batteries, grid-connected power circuits, and grid-connected control circuits, and belongs to the field of DC bus voltage regulation and control. Background Technology

[0002] In the DC power supply system of UAV onboard equipment, in order to ensure that the UAV can reliably complete its mission, while the generator provides power to the bus, an energy storage battery is added as an emergency backup power source for the DC bus. In the event of generator failure, the energy in the battery provides power to the onboard equipment, enabling the flight to continue.

[0003] DC grid connection of energy storage batteries typically employs power diodes. Because diodes exhibit voltage drop in the on-state, this reduces the operating voltage established by the battery on the bus. Furthermore, the power dissipation of the diodes wastes some of the battery's energy and increases the ambient temperature at the diode's installation location. Therefore, this grid connection control method has significant drawbacks and requires technical optimization. Summary of the Invention

[0004] To address the technical challenges of voltage drop, power consumption, and temperature rise associated with using power diodes for battery grid connection, this invention provides a low-power, highly reliable, and logically simple DC grid-connected energy storage battery system.

[0005] This invention provides a DC grid-connected energy storage battery system for preventing bus current feedback. The system includes a battery unit 1, a load unit 2, a power generation unit 3, a MOSFET unit 4, an ideal diode unit 5, a freewheeling diode unit 6, a battery voltage isolation sampling unit 7, a data processing unit 8, a bus voltage isolation sampling unit 9, and an isolation drive unit 10.

[0006] The MOS transistor unit 4, ideal diode unit 5, and freewheeling diode unit 6 serve as grid-connected power channels, connected in series between the battery unit 1 and the load unit 2 to achieve energy transmission; or the power generation unit (3) provides energy to the load unit (2); the battery unit 1, load unit 2, power generation unit 3, MOS transistor unit 4, ideal diode unit 5, and freewheeling diode unit 6 constitute the power part of the energy storage battery DC grid-connected system;

[0007] The data processing unit 8 is used to analyze and compare the voltage data uploaded by the battery voltage isolation sampling unit 7 and the bus voltage isolation sampling unit 9, and to realize the on / off drive control of the MOS transistor unit 4 by the isolation drive unit 10; the battery voltage isolation sampling unit 7, the data processing unit 8, the bus voltage isolation sampling unit 9, and the isolation drive unit 10 are the control part of the DC grid-connected energy storage battery system.

[0008] Preferably, when the battery voltage uploaded by the battery voltage isolation sampling unit 7 is higher than the bus voltage uploaded by the bus voltage isolation sampling unit 9, the battery unit 1 supplies power to the load unit 2 through the MOS transistor unit 4 and the ideal diode unit 5, and the parallel freewheeling diode unit 6 serves as a redundant grid-connected power channel.

[0009] Preferably, when the bus voltage uploaded by the bus voltage isolation sampling unit 9 is higher than the battery voltage uploaded by the battery voltage isolation sampling unit 7, and the voltage difference is not less than the drain-source voltage difference threshold A that turns off the ideal diode unit 5, the MOS transistor unit 4 and the ideal diode unit 5 are disconnected, the freewheeling diode unit 6 is reverse-cut off, and the grid connection channel is turned off.

[0010] Preferably, when the bus voltage uploaded by the bus voltage isolation sampling unit 9 is higher than the battery voltage uploaded by the battery voltage isolation sampling unit 7, and the voltage difference is less than the threshold A for the drain-source voltage difference of the ideal diode unit 5, both the MOS transistor unit 4 and the ideal diode unit 5 remain in the on state, and the battery unit 1 is trickled charged using the bus energy.

[0011] Preferably, when the voltage of battery cell 1 reaches the bus voltage during trickle charging, MOSFET cell 4 is turned off, freewheeling diode cell 6 remains reverse-biased and the grid connection channel is shut off. This enables the battery to be used in the grid-connected application of the bus current feedback system.

[0012] Compared with the prior art, the system described in this invention can achieve the following technical effects:

[0013] 1. The power channel formed by the MOSFET unit and the ideal diode unit has extremely low power consumption when connected to the grid;

[0014] 2. Even if the power channel formed by the MOSFET unit and the ideal diode unit fails due to open circuit, the freewheeling diode unit can still serve as the power channel to achieve grid connection, resulting in high system reliability.

[0015] 3. When the bus voltage is higher than the battery voltage and the voltage difference is not less than the threshold A of the drain-source voltage difference that turns off the ideal diode, both power channels are in the off state to prevent the battery from being damaged by the large current impact of the bus feedback current, ensuring timely protection and reliable shutdown.

[0016] 4. The data processing unit has the ability to compare and analyze the magnitude of the battery voltage and the bus voltage. The data processing unit uses the threshold of the drain-source voltage difference when the ideal diode is turned off as the threshold B for the isolation drive unit to drive the MOS transistor unit to turn off, i.e., B=A. When the difference between the bus voltage and the actual battery voltage is less than B, both the MOS transistor unit and the ideal diode unit remain in the on state, using the bus energy to trickle charge the battery, resulting in high bus energy utilization.

[0017] 5. The data processing unit has the ability to compare and analyze the actual voltage of the battery with the rated voltage. When the actual voltage of the battery is equal to the bus voltage C, the MOSFET unit is turned off to avoid the performance degradation and overvoltage damage caused by the long-term float charging of the battery due to the small current feedback current of the bus. The protection mechanism is comprehensive.

[0018] 6. When the bus voltage is higher than the battery voltage and the voltage difference is not less than the drain-source voltage difference threshold A that turns off the ideal diode, both the MOSFET unit and the ideal diode unit are turned off. The MOSFET and the ideal diode jointly bear the abnormal reverse high voltage. From the analysis of the reverse breakdown failure mode of the MOSFET and the ideal diode, the reverse overvoltage breakdown risk of each is small, and the selection of component withstand voltage parameters is easy.

[0019] 7. The sampling circuit and driving circuit both adopt an isolation design, which ensures high reliability of the signal circuit and high safety for operators when repairing the signal circuit. Attached Figure Description

[0020] Appendix Figure 1 This is a schematic diagram of the principle of a DC grid-connected energy storage battery system for preventing bus current feedback, as described in this invention.

[0021] Appendix Figure 1 The components are labeled as follows: 01-Battery unit, 02-Load unit, 03-Generator unit, 04-MOS transistor unit, 05-Ideal diode unit, 06-Freewheeling diode unit, 07-Battery voltage isolation sampling unit, 08-Data processing unit, 09-Bus voltage isolation sampling unit, 10-Isolation drive unit. Detailed Implementation

[0022] Combined with appendix Figure 1 The preferred embodiments of the present invention will be described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0023] This invention provides a DC grid-connected energy storage battery system to prevent bus current feedback. The DC grid-connected energy storage battery system includes a battery unit 1, a load unit 2, a power generation unit 3, a MOSFET unit 4, an ideal diode unit 5, a freewheeling diode unit 6, a battery voltage isolation sampling unit 7, a data processing unit 8, a bus voltage isolation sampling unit 9, and an isolation drive unit 10. The MOSFET unit 4, the ideal diode unit 5, and the freewheeling diode unit 6 serve as grid-connected power channels and are connected in series between the battery unit 1 and the load unit 2 to achieve energy transmission. Alternatively, the power generation unit (3) can be used to provide energy to the load unit (2). The battery unit 1, load unit 2, power generation unit 3, MOSFET unit 4, ideal diode unit 5, and freewheeling diode unit 6 constitute the power section of the energy storage battery DC grid-connected system. The data processing unit 8 is used to analyze and compare the voltage data uploaded by the battery voltage isolation sampling unit 7 and the bus voltage isolation sampling unit 9, and to realize the on / off drive control of the MOSFET unit 4 by the isolation drive unit 10. The battery voltage isolation sampling unit 7, data processing unit 8, bus voltage isolation sampling unit 9, and isolation drive unit 10 constitute the control section of the energy storage battery DC grid-connected system. When the battery voltage uploaded by the battery voltage isolation sampling unit 7 is higher than the bus voltage uploaded by the bus voltage isolation sampling unit 9, the battery unit 1 supplies power to the load unit 2 through the MOSFET unit 4 and the ideal diode unit 5, and the parallel freewheeling diode unit 6 serves as a redundant grid-connected power channel. When the bus voltage uploaded by the bus voltage isolation sampling unit 9 is higher than the battery voltage uploaded by the battery voltage isolation sampling unit 7, and the voltage difference is not less than the drain-source voltage difference threshold A that turns off the ideal diode unit 5, the MOS transistor unit 4 and the ideal diode unit 5 are disconnected, the freewheeling diode unit 6 is reverse-biased and the grid connection channel is turned off. When the bus voltage uploaded by the bus voltage isolation sampling unit 9 is higher than the battery voltage uploaded by the battery voltage isolation sampling unit 7, and the voltage difference is less than the drain-source voltage difference threshold A that turns off the ideal diode unit 5, both the MOS transistor unit 4 and the ideal diode unit 5 remain on, using bus energy to trickle charge the battery unit 1.

[0024] The power channel formed by the MOS transistor unit and the ideal diode unit of this invention has extremely low power consumption during grid-connected operation. Even in the event of an open-circuit failure of the power channel formed by the MOS transistor unit and the ideal diode unit, the freewheeling diode unit still serves as the power channel for grid connection, ensuring high system reliability. It prevents damage to the battery from large current surges caused by bus feedback current, providing timely protection and reliable shutdown. It utilizes bus energy for trickle charging of the battery, resulting in high bus energy utilization. It avoids performance degradation and the risk of overvoltage damage from long-term float charging due to small currents from bus feedback current, providing comprehensive protection. Abnormal reverse high voltage on the bus is jointly borne by the MOS transistor and the ideal diode, minimizing the risk of reverse overvoltage breakdown for each, and facilitating the selection of component withstand voltage parameters. The battery voltage isolation sampling unit 7, the bus voltage isolation sampling unit 9, and the isolation drive unit 10 all employ isolation design, ensuring high reliability of the signal circuit and high operator safety during signal circuit maintenance.

[0025] According to one embodiment of the present invention, when the voltage of battery cell 1 reaches the bus voltage during trickle charging, MOSFET cell 4 is turned off, freewheeling diode cell 6 remains reverse-biased and the grid connection channel is turned off. This enables the grid-connected application of the battery in the bus current feedback system.

[0026] In a specific embodiment of this invention, the ideal diode unit has a built-in driver chip. The driver chip turns off the ideal diode at a drain-source voltage difference threshold of A = 0.5V. In the DC grid, the generator's minimum output voltage is 1.0V higher than the battery's maximum voltage. The generator supplies power to the bus, and both of the battery's grid-connected power channels are turned off. When the generator's energy is depleted or it cannot operate, the battery supplies power to the grid through the grid-connected power channel formed by the MOSFET unit and the ideal diode unit. The induced electromotive force generated by the load causes the bus voltage to be unstable. When the bus voltage is 0.5V or higher than the actual battery voltage, the grid-connected power channel formed by the MOSFET unit and the ideal diode unit is momentarily turned off, while the freewheeling diode unit's grid-connected power channel remains off to prevent bus current feedback. When the induced electromotive force generated by the load causes the bus voltage to be unstable, and the bus voltage is 0.5V or higher than the actual battery voltage, the grid-connected power channel formed by the MOSFET unit and the ideal diode unit is turned on, and the bus energy charges the battery. When the battery is charged by a small current from the bus, and the actual voltage reaches the rated voltage, the MOSFET unit turns off. The grid-connected power path formed by the MOSFET unit and the ideal diode unit is switched off, while the grid-connected power path of the freewheeling diode unit remains off. When the grid-connected power path formed by the MOSFET unit and the ideal diode unit fails due to open circuit, the battery is connected to the grid for power supply through the grid-connected power path formed by the freewheeling diode unit.

[0027] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or principle transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A DC grid-connected energy storage battery system for preventing bus current feedback, characterized in that, The energy storage battery DC grid-connected system includes a battery unit (1), a load unit (2), a power generation unit (3), a MOSFET unit (4), an ideal diode unit (5), a freewheeling diode unit (6), a battery voltage isolation sampling unit (7), a data processing unit (8), a bus voltage isolation sampling unit (9), and an isolation drive unit (10); wherein, The MOS transistor unit (4), ideal diode unit (5), and freewheeling diode unit (6) serve as grid-connected power channels, connected in series between the battery unit (1) and the load unit (2) to achieve energy transfer; or the power generation unit (3) provides energy to the load unit (2); the battery unit (1), load unit (2), power generation unit (3), MOS transistor unit (4), ideal diode unit (5), and freewheeling diode unit (6) constitute the power part of the energy storage battery DC grid-connected system; The data processing unit (8) is used to analyze and compare the voltage data uploaded by the battery voltage isolation sampling unit (7) and the bus voltage isolation sampling unit (9), and realize the on / off drive control of the MOS transistor unit (4) by the isolation drive unit (10); the battery voltage isolation sampling unit (7), the data processing unit (8), the bus voltage isolation sampling unit (9), and the isolation drive unit (10) are the control part of the DC grid-connected energy storage battery system.

2. The energy storage battery DC grid-connected system for preventing bus current feedback according to claim 1, characterized in that, When the battery voltage uploaded by the battery voltage isolation sampling unit (7) is higher than the bus voltage uploaded by the bus voltage isolation sampling unit (9), the battery unit (1) supplies power to the load unit (2) through the MOS transistor unit (4) and the ideal diode unit (5), and the parallel freewheeling diode unit (6) serves as a redundant grid-connected power channel.

3. The energy storage battery DC grid-connected system for preventing bus current feedback according to claim 1, characterized in that, When the bus voltage uploaded by the bus voltage isolation sampling unit (9) is higher than the battery voltage uploaded by the battery voltage isolation sampling unit (7), and the voltage difference is not less than the drain-source voltage difference threshold A that turns off the ideal diode unit (5), the MOS transistor unit (4) and the ideal diode unit (5) are disconnected, the freewheeling diode unit (6) is reverse cut off, and the grid connection channel is turned off.

4. The energy storage battery DC grid-connected system for preventing bus current feedback according to claim 1, characterized in that, When the bus voltage uploaded by the bus voltage isolation sampling unit (9) is higher than the battery voltage uploaded by the battery voltage isolation sampling unit (7), and the voltage difference is less than the threshold A of the drain-source voltage difference of the ideal diode unit (5), both the MOS transistor unit (4) and the ideal diode unit (5) remain in the on state, and the battery unit (1) is trickled charged using the bus energy.

5. A DC grid-connected energy storage battery system for preventing bus current feedback according to claim 1, characterized in that, When the trickle charge causes the voltage of the battery unit (1) to reach the bus voltage, the MOS transistor unit (4) is turned off, the freewheeling diode unit (6) remains reverse cut off, and the grid connection channel is turned off.

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