A battery wake-up method and system for energy storage inverter

Abstract

The present invention discloses a battery wake-up method and system for an energy storage inverter. A grid voltage sampling unit is used to collect grid voltage and, based on its phase-locked function, a phase-shift triggering method is used to turn on a controllable semiconductor switch to achieve soft starting of a busbar. No zero-crossing detection circuit is required to reduce the impact of the grid on the busbar capacitor. By turning on two controllable mechanical switches connected in series between the inverter module and the grid, a DC-DC module is used to wake up the battery unit. This method has a low structural complexity, does not increase costs, and can reduce battery energy loss and increase battery life.

Description

Technical Field

[0001] The present invention relates to the technical field of inverter systems, and in particular to a battery wake-up method and system for an energy storage inverter. Background Art

[0002] Energy storage inverters have strict power consumption requirements, especially in off-grid systems, requiring a battery sleep function. However, existing conventional systems struggle to achieve deep sleep. When not in use or communicating, they can only operate at low power, which still depletes battery energy and reduces battery life. Therefore, the battery must be put into sleep mode when not in use or communicating, and then awakened when needed. However, existing energy storage inverters lack this capability, and external battery wake-up devices are typically used, which are complex and costly. Summary of the Invention

[0003] To solve the above technical defects, the technical solution adopted by the present invention is to provide a battery wake-up system for an energy storage inverter, including a battery unit, an inverter module and a bus soft start circuit, the inverter module including a DC-DC module, a bus capacitor and an inverter circuit connected in sequence, the bus soft start circuit including a grid voltage sampling unit, a switch unit and a controller, the DC-DC module is electrically connected to the battery unit, the grid voltage sampling unit is connected in parallel at both ends of the grid, and switch units are respectively arranged between the neutral wire and the live wire at the output end of the inverter circuit and the two ends of the grid, the switch unit includes a controllable mechanical switch and a controllable semiconductor switch arranged in parallel, the two controllable semiconductor switches are arranged in opposite directions, and the controllable mechanical switch, the controllable semiconductor switch and the grid voltage sampling unit are respectively electrically connected to the controller.

[0004] Furthermore, the controllable mechanical switch is a relay.

[0005] Furthermore, the controllable semiconductor switch is a thyristor or a fully controlled device without a body diode.

[0006] Furthermore, the inverter circuit is a full-bridge inverter circuit, which includes a first switching tube, a second switching tube, a third switching tube and a fourth switching tube. The first switching tube and the third switching tube are connected in series, and the second switching tube and the fourth switching tube are connected in series. The first switching tube and the second switching tube are respectively connected to the first end of the bus capacitor, and the third switching tube and the fourth switching tube are respectively connected to the second end of the bus capacitor. One relay is connected to the series connection of the second switching tube and the fourth switching tube, and the other relay is connected to the series connection of the first switching tube and the third switching tube.

[0007] Furthermore, the controller is a DSP controller.

[0008] The present invention also provides a battery wake-up method for an energy storage inverter, which is applied to the battery wake-up system, comprising the following steps:

[0009] Collect the grid voltage and calculate the grid phase at this time through the phase-locked loop;

[0010] The phase-shift triggering method is used to gradually reduce the grid phase angle when the controllable semiconductor switch is turned on, and pulse signals are applied to the two controllable semiconductor switches in sequence to control their opening and closing.

[0011] Keeping the two controllable semiconductor switches in an on state at a final phase angle;

[0012] When the detected bus voltage is greater than the set multiple of the effective value of the grid voltage, the two controllable mechanical switches are closed to complete the bus soft start. When the detected bus voltage is less than the set multiple of the effective value of the grid voltage, the controllable semiconductor switches are repeatedly kept in the open state until the bus soft start is successful.

[0013] The battery is awakened through the DC-DC module.

[0014] Furthermore, the phase-shift triggering method is used to gradually reduce the grid phase angle when the controllable semiconductor switch is turned on, and pulse signals are sequentially applied to the two controllable semiconductor switches to control their opening and closing, including the following steps:

[0015] In the first cycle, a first duty cycle is given to the controllable semiconductor switch to make it conductive. When the grid phase is 180° and the difference between the first duty cycle and the phase of the controllable semiconductor switch, the controllable semiconductor switch connected to the live wire of the inverter circuit is turned on. When the grid voltage reaches a negative value, the controllable semiconductor switch is naturally turned off.

[0016] Then, when the grid phase is the difference between 360° and the degree corresponding to the first duty cycle, the controllable semiconductor switch connected to the neutral line of the inverter circuit is turned on, and when the grid voltage is negative, the controllable semiconductor switch is naturally turned off;

[0017] In the second cycle, the duty cycle is increased, a second duty cycle is given to the controllable semiconductor switch to make it conductive, and then the two controllable semiconductor switches are turned on and off in sequence at the corresponding grid phase and negative value;

[0018] The duty cycle is increased in sequence in subsequent cycles until the controllable semiconductor switch is turned on when the grid phase is the degree corresponding to the first duty cycle.

[0019] Furthermore, the set multiple is N, where 1.25 <N<1.4。

[0020] Furthermore, the first duty cycle is 1 / 40-1 / 20 of the pulse signal period.

[0021] Furthermore, the difference between the second duty cycle and the first duty cycle is ΔD, where ΔD=5-10°.

[0022] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0023] The present invention provides a battery wake-up method and system for an energy storage inverter. A grid voltage sampling unit is used to collect grid voltage and, based on its phase-locked function, a phase-shift triggering method is used to turn on a controllable semiconductor switch to achieve soft starting of the busbar. No zero-crossing detection circuit is required to reduce the impact of the grid on the busbar capacitor. By turning on two controllable mechanical switches connected in series between the inverter module and the grid, a DC-DC module is used to wake up the battery unit. This method has low structural complexity, does not increase costs, reduces battery energy loss, and increases battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 This is a circuit schematic diagram of a battery wake-up system for an energy storage inverter provided by an embodiment of the present invention;

[0026] Figure 2 This is a flow chart of a battery wake-up method for an energy storage inverter provided by an embodiment of the present invention;

[0027] Figure 3 This is a timing logic waveform diagram of a thyristor provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] See also Figure 1As shown, the present invention provides a battery wake-up system for an energy storage inverter, including a battery unit, an inverter module and a bus soft start circuit. The inverter module includes a DC-DC module, a bus capacitor C1 and an inverter circuit connected in sequence. The bus soft start circuit includes a grid voltage sampling unit, a switch unit and a controller. The DC-DC module is electrically connected to the battery unit. The grid voltage sampling unit is connected in parallel at both ends of the grid. Switch units are respectively arranged between the neutral wire and the live wire at the output end of the inverter circuit and the two ends of the grid. The switch unit includes a controllable mechanical switch and a controllable semiconductor switch arranged in parallel. The two controllable semiconductor switches are arranged in opposite directions. The controllable mechanical switch, the controllable semiconductor switch and the grid voltage sampling unit are respectively electrically connected to the controller.

[0031] Preferably, the controllable mechanical switch is a relay.

[0032] In this embodiment, the relay K1 is provided between the L line of the inverter circuit output end and the first end of the grid, and the relay K2 is provided between the N line of the inverter circuit output end and the second end of the grid.

[0033] Preferably, the controllable semiconductor switch is a thyristor or a fully controlled device without a body diode.

[0034] In this embodiment, the controllable semiconductor switches are thyristors SCR1 and SCR2.

[0035] Specifically, the inverter circuit is a full-bridge inverter circuit, which includes a first switching tube V1, a second switching tube V2, a third switching tube V3 and a fourth switching tube V4. The first switching tube V1 and the third switching tube V3 are connected in series, and the second switching tube V2 and the fourth switching tube V4 are connected in series. The first switching tube V1 and the second switching tube V2 are respectively connected to the first end of the bus capacitor C1, and the third switching tube V3 and the fourth switching tube V4 are respectively connected to the second end of the bus capacitor C1. One relay K1 is connected to the series connection of the second switching tube V2 and the fourth switching tube V4, and the other relay K2 is connected to the series connection of the first switching tube V1 and the third switching tube V3.

[0036] In this embodiment, the first switch tube V1 , the second switch tube V2 , the third switch tube V3 and the fourth switch tube V4 are MOSFET tubes or IGBT tubes.

[0037] Specifically, the controller is a DSP controller.

[0038] like Figure 2-3 As shown, the present invention also provides a battery wake-up method for an energy storage inverter, which is applied to the above-mentioned battery wake-up system and includes the following steps:

[0039] Collect the grid voltage and calculate the grid phase at this time through the phase-locked loop;

[0040] The phase-shift triggering method is used to gradually reduce the grid phase angle when the controllable semiconductor switch is turned on, and pulse signals are applied to the two controllable semiconductor switches in sequence to control their opening and closing.

[0041] Keeping the two controllable semiconductor switches in an on state at a final phase angle;

[0042] When the detected bus voltage is greater than the set multiple of the effective value of the grid voltage, the two controllable mechanical switches are closed to complete the bus soft start. When the detected bus voltage is less than the set multiple of the effective value of the grid voltage, the controllable semiconductor switches are repeatedly kept in the open state until the bus soft start is successful.

[0043] The battery is awakened through the DC-DC module.

[0044] When the presence of a power grid is detected, the voltage of the power grid is collected using a power grid voltage sampling unit.

[0045] In this embodiment, the set multiple is N, where 1.25 <N<1.4。

[0046] Preferably, a phase-shift triggering method is adopted to gradually reduce the grid phase angle when the controllable semiconductor switch is turned on, and pulse signals are sequentially applied to the two controllable semiconductor switches to control their opening and closing, including the following steps:

[0047] In the first cycle, a first duty cycle is given to the controllable semiconductor switch to make it conductive. When the grid phase is 180° and the difference between the first duty cycle and the phase of the controllable semiconductor switch, the controllable semiconductor switch connected to the live wire of the inverter circuit is turned on. When the grid voltage reaches a negative value, the controllable semiconductor switch is naturally turned off.

[0048] Then, when the grid phase is the difference between 360° and the first duty cycle, the controllable semiconductor switch connected to the neutral line of the inverter circuit is turned on, and when the grid voltage is negative, the controllable semiconductor switch is naturally turned off;

[0049] In the second cycle, the duty cycle is increased, a second duty cycle is given to the controllable semiconductor switch to make it conductive, and then the two controllable semiconductor switches are turned on and off in sequence at the corresponding grid phase and negative value;

[0050] The duty cycle is increased in sequence in subsequent cycles until the controllable semiconductor switch is turned on when the grid phase is the degree corresponding to the first duty cycle.

[0051] Specifically, the first duty cycle is 1 / 40-1 / 20 of the pulse signal period.

[0052] Specifically, the difference between the second duty cycle and the first duty cycle is ΔD, where ΔD=5-10°.

[0053] In this embodiment, the first duty cycle is 5°, that is, when the grid phase is 175°, SCR1 is turned on, and when the grid phase is 355°, SCR2 is turned on. The duty cycle of the second cycle is increased to 10°, that is, when the grid phase is 170°, SCR1 is turned on, and when the grid phase is 350°, SCR2 is turned on. The duty cycle increases by 5° every other cycle until the thyristor is turned on when the grid phase is 5°, that is, when SCR1 is turned on, the grid voltage phase is 5°, and when SCR2 is turned on, the grid voltage phase is 185°. Then the thyristors SCR1 and SCR2 are kept turned on at this angle.

[0054] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A battery wake-up method for an energy storage inverter, applied to a battery wake-up system, characterized in that: The battery wake-up system includes a battery unit, an inverter module, and a bus soft-start circuit. The inverter module includes a DC-DC module, a bus capacitor, and an inverter circuit connected in sequence. The bus soft-start circuit includes a grid voltage sampling unit, a switch unit, and a controller. The DC-DC module is electrically connected to the battery unit. The grid voltage sampling unit is connected in parallel at both ends of the grid. Switch units are respectively provided between the neutral wire and the live wire at the output end of the inverter circuit and the two ends of the grid. The switch unit includes a controllable mechanical switch and a controllable semiconductor switch arranged in parallel. The two controllable semiconductor switches are arranged in opposite directions. The controllable mechanical switch, the controllable semiconductor switch, and the grid voltage sampling unit are respectively electrically connected to the controller. The battery wake-up method comprises the following steps: Collect the grid voltage and calculate the grid phase at this time through the phase-locked loop; The phase-shift triggering method is used to gradually reduce the grid phase angle when the controllable semiconductor switch is turned on, and pulse signals are applied to the two controllable semiconductor switches in sequence to control their opening and closing. Keeping the two controllable semiconductor switches in an on state at a final phase angle; When the detected bus voltage is greater than the set multiple of the effective value of the grid voltage, the two controllable mechanical switches are closed to complete the bus soft start. When the detected bus voltage is less than the set multiple of the effective value of the grid voltage, the controllable semiconductor switches are repeatedly kept in the open state until the bus soft start is successful. The battery is awakened through the DC-DC module.

2. The battery wake-up method of the energy storage inverter according to claim 1, characterized in that: The phase-shift triggering method is used to gradually reduce the grid phase angle when the controllable semiconductor switch is turned on, and pulse signals are applied to the two controllable semiconductor switches in sequence to control their opening and closing, including the following steps: In the first cycle, a first duty cycle is given to the controllable semiconductor switch to make it conductive. When the grid phase is 180° and the difference between the first duty cycle and the phase of the controllable semiconductor switch, the controllable semiconductor switch connected to the live wire of the inverter circuit is turned on. When the grid voltage reaches a negative value, the controllable semiconductor switch is naturally turned off. Then, when the grid phase is the difference between 360° and the first duty cycle, the controllable semiconductor switch connected to the neutral line of the inverter circuit is turned on, and when the grid voltage is negative, the controllable semiconductor switch is naturally turned off; In the second cycle, the duty cycle is increased, a second duty cycle is given to the controllable semiconductor switch to make it conductive, and then the two controllable semiconductor switches are turned on and off in sequence at the corresponding grid phase and negative value; The duty cycle is increased in sequence in subsequent cycles until the controllable semiconductor switch is turned on when the grid phase is the degree corresponding to the first duty cycle.

3. The battery wake-up method for an energy storage inverter according to claim 1, wherein: The multiple of the setting is N, where 1.25 <N<1.4。 4. The battery awakening method of the energy storage inverter according to claim 2, wherein: The first duty cycle is 1 / 40-1 / 20 of the pulse signal period.

5. The battery awakening method for an energy storage inverter according to claim 2 or 4, characterized in that: The difference between the second duty cycle and the first duty cycle is ΔD, where ΔD=5-10°.

6. The battery awakening method of the energy storage inverter according to claim 1, wherein: The controllable mechanical switch is a relay.

7. The battery awakening method for an energy storage inverter according to claim 1 or 6, characterized in that: The controllable semiconductor switch is a thyristor or a fully controlled device without a body diode.

8. The battery awakening method for an energy storage inverter according to claim 1, wherein: The inverter circuit is a full-bridge inverter circuit, which includes a first switching tube, a second switching tube, a third switching tube and a fourth switching tube. The first switching tube and the third switching tube are connected in series, and the second switching tube and the fourth switching tube are connected in series. The first switching tube and the second switching tube are respectively connected to the first end of the bus capacitor, and the third switching tube and the fourth switching tube are respectively connected to the second end of the bus capacitor. One relay is connected to the series connection of the second switching tube and the fourth switching tube, and another relay is connected to the series connection of the first switching tube and the third switching tube.

9. The battery awakening method for an energy storage inverter according to claim 1 or 8, characterized in that: The controller is a DSP controller.

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