A bootstrap driven half-bridge inverter and its startup method and an energy storage system

Abstract

This invention discloses a bootstrap-driven half-bridge inverter, its startup method, and an energy storage system. The half-bridge inverter includes a first switch, a second switch, a positive bus capacitor, a negative bus capacitor, a bootstrap circuit, a first switch drive circuit, and a second switch drive circuit. The bootstrap circuit includes a drive power supply, and the second switch drive circuit is connected between the two ends of the drive power supply. The startup method includes: sending a lock-in signal to the first switch drive circuit and sending a drive signal with a duty cycle less than a preset threshold to the second switch drive circuit, so that the drive power supply charges the bootstrap capacitor in the first switch drive circuit; after the bootstrap capacitor in the first switch drive circuit is fully charged, sending complementary duty cycle signals to the first and second switch drive circuits. This invention can improve the startup reliability and output power quality of half-bridge inverters using bootstrap drive circuits.

Description

Technical Field

[0001] This invention relates to the field of energy storage system technology, and in particular to a bootstrap driven half-bridge inverter and its startup method, as well as an energy storage system. Background Technology

[0002] Since the sources of the two transistors in the bridge arm of a half-bridge inverter circuit are not grounded, there are two driving schemes: one is to use an isolated driving circuit, and the other is to use a bootstrap driving circuit. Among them, the bootstrap driving circuit is simpler and cheaper.

[0003] However, existing bootstrap drive circuits typically subject half-bridge inverters to huge surge voltages during startup, which can easily lead to voltage waveform distortion.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a bootstrap-driven half-bridge inverter, its startup method, and an energy storage system, which can improve the startup reliability and output power quality of half-bridge inverters using bootstrap-driven circuits.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention discloses a startup method for a bootstrap driven half-bridge inverter. The bootstrap driven half-bridge inverter includes a half-bridge inverter power section and a half-bridge inverter drive section. The half-bridge inverter power section includes a first switch, a second switch, a positive bus capacitor, and a negative bus capacitor. The first switch and the second switch are connected in series at both ends of a bus to form a first branch. The positive bus capacitor and the negative bus capacitor are connected at both ends of a bus to form a second branch. The half-bridge inverter power section is connected to a load. The first end of the load is connected between the first switch and the second switch on the first branch. The second end of the load... The terminal is connected between the positive bus capacitor and the negative bus capacitor on the second branch; the half-bridge inverter drive unit includes a bootstrap circuit, a first switch drive circuit, and a second switch drive circuit. The first switch drive circuit is connected to the drive terminal of the first switch to drive the first switch, and the second switch drive circuit is connected to the drive terminal of the second switch to drive the second switch. The bootstrap circuit includes a drive power supply. One end of the drive power supply is connected to the first switch drive circuit, and the other end is connected to the bus terminal. The second switch drive circuit is connected between the two ends of the drive power supply. The startup method includes the following steps: S1: Send a lock signal to the first switch driver circuit and a drive signal with a duty cycle less than a preset threshold to the second switch driver circuit, so that the drive power supply charges the bootstrap capacitor in the first switch driver circuit. S2: After the bootstrap capacitor in the first switch driver circuit is fully charged, a complementary duty cycle signal is sent to the first switch driver circuit and the second switch driver circuit.

[0007] Preferably, in step S1, a drive signal with a duty cycle of 1% to 5% is sent to the second switch drive circuit.

[0008] Preferably, a signal indicating continuous shutdown is sent to the first switching transistor drive circuit.

[0009] Preferably, in step S2, complementary duty cycle signals are sent to the first switch driving circuit and the second switch driving circuit: wherein the duty cycle of the first switch is: D QH = 0.5*(1 +Asin(-ωt)), where D QH Let D be the duty cycle of the first switch, A be the modulation ratio (a dimensionless constant between 0 and 1), and ω be the angular frequency; the duty cycle of the second switch is: D QL = 1-D QH .

[0010] Preferably, the bootstrap capacitor in the first switch driving circuit being fully charged means that the capacity of the bootstrap capacitor in the first switch driving circuit is sufficient to drive the first switch.

[0011] Secondly, the present invention discloses a bootstrap driven half-bridge inverter, comprising a half-bridge inverter power section and a half-bridge inverter drive section. The half-bridge inverter power section includes a first switch, a second switch, a positive bus capacitor, and a negative bus capacitor. The first switch and the second switch are connected in series at both ends of a bus to form a first branch. The positive bus capacitor and the negative bus capacitor are connected at both ends of a bus to form a second branch. The half-bridge inverter power section is connected to a load. The first end of the load is connected between the first switch and the second switch on the first branch, and the second end of the load is connected to the positive bus capacitor and the negative bus capacitor on the second branch. The half-bridge inverter drive unit includes a bootstrap circuit, a first switch drive circuit, and a second switch drive circuit. The first switch drive circuit is connected to the drive terminal of the first switch to drive the first switch, and the second switch drive circuit is connected to the drive terminal of the second switch to drive the second switch. The bootstrap circuit includes a drive power supply, one end of which is connected to the first switch drive circuit, and the other end is connected to a bus terminal. The second switch drive circuit is connected between the two ends of the drive power supply. The bootstrap drive half-bridge inverter is configured to perform the startup method described in the first aspect for startup.

[0012] Thirdly, the present invention discloses an energy storage system, including the bootstrap driven half-bridge inverter described in the second aspect.

[0013] Fourthly, the present invention discloses a computer-readable storage medium storing a computer program, wherein the computer program is configured to be run by a processor to perform the bootstrap-driven half-bridge inverter startup method described in the first aspect.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: The bootstrap driven half-bridge inverter and its startup method, along with an energy storage system disclosed in this invention, first drive the second switching transistor with a very small duty cycle to charge the bootstrap capacitor, avoiding the negative voltage output caused by the second switching transistor being on for a long time in the traditional method, and reducing the voltage waveform distortion caused by the second switching transistor being turned on alone during the bootstrap startup process; after the bootstrap capacitor is fully charged, complementary sine wave modulation is used to achieve rapid soft start, avoiding voltage sudden changes and reducing startup impact. The two work together to ultimately achieve a smooth and distortion-free soft start process, improving system reliability.

[0015] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0016] Figure 1 This is a flowchart of the bootstrap-driven half-bridge inverter startup method disclosed in Embodiment 1 of the present invention; Figure 2 This is a circuit diagram of a bootstrap driven half-bridge inverter according to a specific embodiment of the present invention; Figure 3a This is a schematic diagram showing the conduction status of each switch and the change in inverter voltage when using the existing startup method; Figure 3b yes Figure 3a Enlarged view of a portion of the time period; Figure 4a This is a schematic diagram showing the conduction status of each switch and the change of inverter voltage in the startup method of a specific embodiment of the present invention. Figure 4b yes Figure 4a Enlarged view of a portion of the time period; Detailed Implementation The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0017] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for both fixing and circuit / signal connectivity.

[0018] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] A preferred embodiment of the present invention discloses a startup method for a bootstrap-driven half-bridge inverter. The bootstrap-driven half-bridge inverter includes a power section and a drive section. The power section includes a first switch, a second switch, a positive bus capacitor, and a negative bus capacitor. The first and second switches are connected in series across the two ends of a bus to form a first branch. The positive and negative bus capacitors are connected across the two ends of the bus to form a second branch. A load is connected to the power section. The first end of the load is connected between the first and second switches on the first branch, and the second end of the load is connected to the second branch. Between the positive bus capacitor and the negative bus capacitor on the line; the half-bridge inverter drive section includes a bootstrap circuit, a first switching transistor drive circuit, and a second switching transistor drive circuit. The first switching transistor drive circuit is connected to the drive terminal of the first switching transistor to drive the first switching transistor, and the second switching transistor drive circuit is connected to the drive terminal of the second switching transistor to drive the second switching transistor. The bootstrap circuit includes a drive power supply, a resistor, and a diode. One end of the drive power supply is connected to the first switching transistor drive circuit, and the other end is connected to the bus terminal. The second switching transistor drive circuit is connected between the two ends of the drive power supply. The first switching transistor drive circuit includes a bootstrap capacitor.

[0021] like Figure 1 As shown, the startup method of the bootstrap driven half-bridge inverter in Embodiment 1 of the present invention includes the following steps: S1: Send a lock signal to the first switch driver circuit and a drive signal with a duty cycle less than a preset threshold to the second switch driver circuit, so that the drive power supply charges the bootstrap capacitor in the first switch driver circuit. Specifically, a continuously off signal is sent to the first switch driving circuit, and a driving signal with a duty cycle of 1% to 5% is sent to the second switch driving circuit.

[0022] In some embodiments, the preset threshold can be a fixed value (1%~5%) or a variable that is dynamically adjusted according to parameters such as bus voltage and load size.

[0023] S2: After the bootstrap capacitor in the first switch driver circuit is fully charged, a complementary duty cycle signal is sent to the first switch driver circuit and the second switch driver circuit.

[0024] The phrase "fully charged" in the first switch driving circuit means that the charge / voltage of the bootstrap capacitor in the first switch driving circuit is sufficient to drive the first switch.

[0025] Specifically, the duty cycle of the first switching transistor is: D QH = 0.5*(1 +Asin(-ωt)); In the formula, D QHHere, A is the duty cycle of the first switching transistor, A is the modulation index, a dimensionless constant between 0 and 1 that determines the amplitude of the output voltage, and ω is the angular frequency, ω = 2π. f , f The rated frequency set for the system. The negative sign in the formula indicates the phase relationship of the modulating wave, ensuring correct correspondence with the complementary signal.

[0026] The duty cycle of the second switch is complementary to that of the first switch, therefore D QL = 1 - D QH .

[0027] The following detailed description of the bootstrap-driven half-bridge inverter startup method of Embodiment 1 of the present invention, in conjunction with specific embodiments, provides further details.

[0028] like Figure 2As shown, the half-bridge inverter 10 includes a power section and a drive section. The power section includes: an upper arm switch QH, a lower arm switch QL, a positive bus capacitor CbusP, a negative bus capacitor CbusN, an inductor L, and a capacitor C; where inductor L and capacitor C are the inverter's output filters. The upper arm switch QH and the lower arm switch QL are connected in series between the positive bus terminal BUS+ and the negative bus terminal BUS- to form a first branch. The positive bus capacitor CbusP and the negative bus capacitor CbusL are connected in series between the positive bus terminal BUS+ and the negative bus terminal BUS- to form a second branch. The half-bridge inverter 10 is connected to a load LOAD. The first end of the load LOAD is connected between the upper arm switch QH and the lower arm switch QL on the first branch, and the second end of the load LOAD is connected between the positive bus capacitor CbusP and the negative bus capacitor CbusN on the second branch. The half-bridge inverter drive section includes a QH drive circuit 20, a QL drive circuit 30, and a bootstrap circuit 40. In the QH drive circuit 20, the drive signal PWMH drives the upper switch QH of the bridge arm through a transistor power amplifier circuit and a drive resistor RgH. The transistor power amplifier circuit in the QH drive circuit 20 is connected in parallel to the bootstrap capacitor CH. In the QL drive circuit 30, the drive signal PWML drives the lower switch QL of the bridge arm through a transistor amplifier circuit and a drive circuit RgL. The transistor power amplifier circuit in the QL drive circuit 30 is connected in parallel to the drive capacitor CL. The bootstrap circuit 40 includes a drive power supply VDD, a current-limiting bootstrap resistor Rboot, and a reverse-biased diode Dboot. One end of the drive power supply VDD is connected to the bootstrap capacitor CH, and the other end is connected to the negative terminal BUS- of the bus. The two ends of the drive capacitor CL are connected to the two ends of the drive power supply VDD, so that the drive power supply VDD can directly charge the drive capacitor CL and also charge the bootstrap capacitor CH. The driving mode of this circuit must be coordinated with the complementary conduction mode of the upper bridge arm switch QH and the lower bridge arm switch QL. When the lower bridge arm switch QL is turned on, the bridge arm equivalent voltage Vs between the upper bridge arm switch QH and the lower bridge arm switch QL on the first branch is reduced to be equal to the negative terminal BUS- of the bus, which turns on the diode Dboot. The drive power supply VDD charges the bootstrap capacitor CH through the bootstrap circuit. The current loop is drive power supply VDD - bootstrap resistor Rboot - diode Dboot - bootstrap capacitor CH - lower bridge arm switch QL - drive power supply VDD. When the lower bridge arm switch QL is turned off, the bridge arm equivalent voltage Vs potential rises. Because the diode Dboot blocks the flow, the energy of the bootstrap capacitor CH cannot flow back.

[0029] For grid-connected inverters, when the grid is connected, the lower arm switch QL and the upper arm switch QH rectify the current, causing them to conduct alternately, and the bootstrap capacitor CH charges naturally. For off-grid inverters, a drawback of this driving method is that initially, the drive power supply VDD first fully charges the drive capacitor CL, and the lower arm switch QL needs to be continuously conducting for a period of time to fully charge the bootstrap capacitor CH. Therefore, there is a time period where only the lower arm switch QL is conducting. During this time, the equivalent voltage Vs of the bridge arm is equal to the voltage Vbus- at the negative terminal of the bus, resulting in a difference in the inverter voltage Vs. LN Waveform distortion, overload.

[0030] like Figure 3a As shown, the horizontal axis represents time, and the vertical axis represents the switching state (1 for on, 0 for off) of the upper switch QH / lower switch QL in the bridge arm. LN This represents the inverter voltage. Using a traditional startup control strategy, the bootstrap capacitor CH has an initial voltage of 0. For the first 2ms, CH is not fully charged and cannot supply power to the QH drive circuit 20. The upper bridge arm switch QH is in the off state. During this period, the lower bridge arm switch QL is modulated by a sine wave, resulting in the inverter voltage V... LN It is a negative voltage and does not follow the sine wave. Figure 3b for Figure 3a The magnified view at 2ms shows that the bootstrap capacitor CH is fully charged, and the switch QH on the bridge arm turns on for the first time and modulates with a sine wave, generating a huge inrush voltage. This invention is proposed based on the defect that the half-bridge inverter is subjected to a huge inrush voltage during startup, which easily leads to voltage waveform distortion.

[0031] A specific embodiment of the present invention provides a startup method for a bootstrap driven half-bridge inverter, which reduces the startup impact of the half-bridge inverter through a soft-start strategy, including the following steps: A1: The controller (e.g., CPU / MCU) sends a drive signal PWML with a duty cycle between 1% and 5%, which causes the lower bridge arm switch QL to turn on briefly and then turn off, the upper bridge arm switch QH to turn off, and the diode Dboot to turn on, so that the drive power supply VDD charges the bootstrap capacitor CH through the bootstrap circuit.

[0032] Due to circuit losses, the short-term conduction of the lower bridge switch QL will not affect the inverter voltage V. LN Change, inverter voltage V LNThe value remains constant at 0. The circuit losses include the switching losses of the lower switch QL and the upper switch QH in the bridge arm, the load load losses, and the parasitic resistance losses in the inductor L and capacitor C. Specifically, due to the presence of switch conduction losses, filter parasitic resistance, and load losses in the circuit, when the lower switch QL is turned on with a very small duty cycle (e.g., 1%-5%), the energy generated is mainly absorbed by these losses. Therefore, in typical application scenarios where the load is not unloaded, the inverter output voltage V... LN The change is extremely small and can be considered to remain approximately zero, thus avoiding the occurrence of... Figure 3a The significant negative voltage distortion is shown. For extreme start-up conditions with no load or near no load, the output filter and load characteristics must meet the above soft-start conditions during circuit design, or the duty cycle of the initial charging pulse may be further reduced.

[0033] The drive signal can be generated not only by the CPU / MCU, but also by a dedicated PWM controller chip or virtual circuit.

[0034] The preset threshold or duty cycle range of 1% to 5% needs to be determined based on the specific circuit parameters. The basic principle is that during the short period when the lower switching transistor QL is turned on, the voltage change ΔV established by the pulse current across the load and filter capacitor should be much smaller than the target output voltage amplitude during normal system operation (typically set to ΔV < 5% * V). bus V bus (This refers to the voltage across the bus). In practical applications, a maximum duty cycle that ensures rapid charging of the bootstrap capacitor without causing significant distortion of the output voltage can be determined through experimental debugging and used as a threshold.

[0035] In the conduction mode of the lower switch (0, The current flows through the half-bus capacitor, filter inductor, output capacitor, and inductor current when the lower switching transistor is turned on. t belongs to (0, The output energy Eo is: The energy stored in the inductor, EL, is: The energy consumed by the equivalent load is: Assume the total loss, including switching loss, filter inductor resistance loss, and output capacitor resistance loss, is Eε, where D is the duty cycle and T is the output capacitor resistance. sw For the switching cycle, R load C is the load equivalent resistance, and C is the output filter capacitor.

[0036] To ensure that the voltage change ΔV established by the pulse current across the load and filter capacitor is much smaller than the target output voltage amplitude during normal system operation (typically set to ΔV < 5% * V), the following conditions must be met. bus V bus (where the voltage across the bus is the voltage across the bus, and the energy conservation condition must be met: Eo + E) = + Eε。 Eo + E Positively correlated with D, in practical applications, a maximum duty cycle that can ensure rapid charging of the bootstrap capacitor without causing significant distortion of the output voltage can be determined through experimental debugging as a threshold.

[0037] A2: Wait for the bootstrap capacitor CH to fully charge; the CPU sends complementary sinusoidal modulation waves PWML and PWMH to drive QL and QH respectively, starting to make the inverter voltage V... LN Slowly rise to the set value, and the start-up is complete.

[0038] The bootstrap capacitor CH is fully charged when it reaches a voltage sufficient to stably drive the switch QH on the bridge arm. The duty cycle of QH is: D QH = 0.5*(1 +Asin(-ωt)), achieving zero-voltage soft start, where A is the modulation index, a dimensionless constant between 0 and 1 that determines the amplitude of the output voltage; ω is the angular frequency; the duty cycle of QL is complementary to that of QH, i.e.: D QL = 1-D QH .

[0039] Specifically, a fully charged bootstrap capacitor means that the voltage across the bootstrap capacitor CH reaches a preset voltage threshold V. charge_th The preset voltage threshold V charge_th It should be ensured that the switch QH on the bridge arm can be fully turned on, which is usually set to: V charge_th ≥ V gs_QH_min + V margin V gs_QH_min It is the minimum fully turn-on gate voltage specified in the QH device datasheet, V margin This is a margin (e.g., 1-2V) reserved to ensure reliability. Whether this threshold has been reached can be determined by setting a voltage detection circuit (such as a voltage divider resistor and a comparator) across the bootstrap capacitor.

[0040] The following detailed description of the startup method of the bootstrap driven half-bridge inverter according to a specific embodiment of the present invention will be provided with specific examples.

[0041] In specific examples, Figure 2Taking a single-phase half-bridge topology as an example, the drive power supply VDD is an ideal voltage source. The capacitance values ​​of the positive bus capacitor CbusP and the negative bus capacitor CbusN are equal, and their voltages meet the inverter requirements. The inverter uses LC filtering. When the lower switch QL of the bridge arm is turned on, the potential of the bridge arm equivalent voltage Vs decreases to be equal to the voltage Vbus- at the negative terminal BUS- of the bus. The drive power supply VDD charges the bootstrap capacitor CH through the bootstrap resistor Rboot and the diode Dboot. When the lower switch QL of the bridge arm is turned off, the potential of the bridge arm equivalent voltage Vs rises. Because the diode Dboot prevents the energy of the bootstrap capacitor CH from flowing back, the bootstrap capacitor CH provides drive energy for the upper switch QH of the bridge arm.

[0042] In the first specific example, based on the startup method of Specific Embodiment 1, the conduction status of the upper bridge arm switch QH and the lower bridge arm switch QL, as well as the inverter voltage V, are obtained. LN Changes such as Figure 4a and Figure 4b As shown, Figure 4a Within the first 20ms, the upper bridge arm switch QH is turned off. The CPU sends a PWML drive signal with a duty cycle between 1% and 5%, which makes the lower bridge arm switch QL conduct for a very short time. Due to circuit losses, the inverter voltage V... LN Keep it at 0; Figure 4b yes Figure 4a The magnified view at 20ms shows that at 20ms, the upper bridge arm switch QH turns on, and the lower bridge arm switch QL and the upper bridge arm switch QH simultaneously begin sinusoidal modulation, increasing the inverter voltage V. LN Soft start.

[0043] Embodiment 2 of the present invention discloses a bootstrap driven half-bridge inverter, comprising a half-bridge inverter power section and a half-bridge inverter drive section. The half-bridge inverter power section includes a first switch, a second switch, a positive bus capacitor, and a negative bus capacitor. The first switch and the second switch are connected in series at both ends of the bus to form a first branch. The positive bus capacitor and the negative bus capacitor are connected at both ends of the bus to form a second branch. A load is connected to the half-bridge inverter power section. The first end of the load is connected between the first switch and the second switch on the first branch, and the second end of the load is connected between the positive bus capacitor and the negative bus capacitor on the second branch. The half-bridge inverter drive unit includes a bootstrap circuit, a first switching transistor drive circuit, and a second switching transistor drive circuit. The first switching transistor drive circuit is connected to the drive terminal of the first switching transistor to drive the first switching transistor, and the second switching transistor drive circuit is connected to the drive terminal of the second switching transistor to drive the second switching transistor. The bootstrap circuit includes a drive power supply, one end of which is connected to the first switching transistor drive circuit, and the other end is connected to the bus terminal. The second switching transistor drive circuit is connected between the two ends of the drive power supply. The bootstrap-driven half-bridge inverter is configured to perform the startup method of Embodiment 1 for startup.

[0044] Embodiment 3 of the present invention discloses an energy storage system, including the bootstrap driven half-bridge inverter of Embodiment 2.

[0045] Embodiment 4 of the present invention discloses a computer-readable storage medium storing a computer program, wherein the computer program is configured to be run by a processor to execute the bootstrap driving half-bridge inverter startup method of Embodiment 1.

[0046] Optionally, the aforementioned computer-readable storage media may include, but are not limited to, various media capable of storing computer programs, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0047] The background section of this invention may include background information about the problems or circumstances surrounding the invention, rather than a description of prior art by others. Therefore, the content included in the background section is not an admission of prior art by the applicant.

[0048] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification without contradiction. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope defined by the appended claims.

Claims

1. A startup method for a bootstrap driven half-bridge inverter, characterized in that, The bootstrap driven half-bridge inverter includes a half-bridge inverter power section and a half-bridge inverter drive section. The half-bridge inverter power section includes a first switch, a second switch, a positive bus capacitor, and a negative bus capacitor. The first switch and the second switch are connected in series at both ends of the bus to form a first branch. The positive bus capacitor and the negative bus capacitor are connected at both ends of the bus to form a second branch. The half-bridge inverter power section is connected to a load. The first end of the load is connected between the first switch and the second switch on the first branch, and the second end of the load is connected to the positive bus capacitor on the second branch. Between the bus capacitor and the negative bus capacitor; the half-bridge inverter drive unit includes a bootstrap circuit, a first switch drive circuit, and a second switch drive circuit. The first switch drive circuit is connected to the drive terminal of the first switch to drive the first switch. The second switch drive circuit is connected to the drive terminal of the second switch to drive the second switch. The bootstrap circuit includes a drive power supply. One end of the drive power supply is connected to the first switch drive circuit, and the other end is connected to the bus terminal. The second switch drive circuit is connected between the two ends of the drive power supply. The startup method includes the following steps: S1: Send a lock signal to the first switch driver circuit and a drive signal with a duty cycle less than a preset threshold to the second switch driver circuit, so that the drive power supply charges the bootstrap capacitor in the first switch driver circuit. S2: After the bootstrap capacitor in the first switch driver circuit is fully charged, a complementary duty cycle signal is sent to the first switch driver circuit and the second switch driver circuit.

2. The startup method for a bootstrap driven half-bridge inverter according to claim 1, characterized in that, In step S1, a drive signal with a duty cycle of 1% to 5% is sent to the second switch drive circuit.

3. The startup method for a bootstrap driven half-bridge inverter according to claim 1, characterized in that, In step S1, a signal to continuously turn off is sent to the first switching transistor drive circuit.

4. The startup method for a bootstrap driven half-bridge inverter according to claim 1, characterized in that, In step S2, complementary duty cycle signals are sent to the first switch driver circuit and the second switch driver circuit: wherein the duty cycle of the first switch is: D QH = 0.5*(1 +Asin(-ωt)), where D QH Let D be the duty cycle of the first switch, A be the modulation ratio (a dimensionless constant between 0 and 1), and ω be the angular frequency; the duty cycle of the second switch is: D QL =1-D QH .

5. The startup method for a bootstrap driven half-bridge inverter according to claim 1, characterized in that, The bootstrap capacitor in the first switching transistor drive circuit being fully charged means that the capacity of the bootstrap capacitor in the first switching transistor drive circuit is sufficient to drive the first switching transistor.

6. A bootstrap driven half-bridge inverter, characterized in that, The system includes a half-bridge inverter power section and a half-bridge inverter drive section. The half-bridge inverter power section includes a first switch, a second switch, a positive bus capacitor, and a negative bus capacitor. The first switch and the second switch are connected in series at both ends of the bus to form a first branch. The positive bus capacitor and the negative bus capacitor are connected at both ends of the bus to form a second branch. The half-bridge inverter power section is connected to a load. The first end of the load is connected between the first switch and the second switch on the first branch, and the second end of the load is connected between the positive bus capacitor and the negative bus capacitor on the second branch. The half-bridge inverter drive section includes a bootstrap circuit, a first switch drive circuit, and a second switch drive circuit. The first switch drive circuit is connected to the drive terminal of the first switch to drive the first switch. The second switch drive circuit is connected to the drive terminal of the second switch to drive the second switch. The bootstrap circuit includes a drive power supply. One end of the drive power supply is connected to the first switch drive circuit, and the other end is connected to the bus terminal. The second switch drive circuit is connected between the two ends of the drive power supply. The bootstrap-driven half-bridge inverter is configured to perform a startup method according to any one of claims 1 to 5.

7. An energy storage system, characterized in that, Includes the bootstrap driven half-bridge inverter as described in claim 6.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, wherein the computer program is configured to be run by a processor to perform the bootstrap-driven half-bridge inverter startup method according to any one of claims 1 to 5.

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