Bootstrap circuit and electronic circuit

Abstract

The utility model discloses a bootstrap circuit and an electronic circuit. The bootstrap circuit is used for an N-phase bridge arm circuit, N is an integer greater than or equal to 2, the bootstrap circuit comprises N bootstrap branches which are connected with N bridge arms of the bridge arm circuit in a one-to-one correspondence manner, each bootstrap branch comprises a capacitor and a diode, in the same bootstrap branch, one end of the capacitor is connected with a connection point of an upper bridge arm and a lower bridge arm in the bridge arms, and the other end of the capacitor is connected with a diode; the anode of the diode is connected with the power supply; wherein the diodes of the at least two bootstrap branches are connected in parallel. According to the bootstrap circuit and the electronic circuit provided by the embodiment of the invention, the bootstrap voltage of the multi-phase bridge arm can be stabilized and balanced.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a bootstrap circuit and an electronic circuit. Background Art

[0002] The full-bridge circuit of multi-phase (such as three-phase) bridge arms is a power conversion topology widely used in the industrial field, especially in the fields of motor drive, generator grid connection, uninterruptible power supply (Uninterruptible Power Supply) and three-phase power factor correction (Power Factor Correction, PFC).

[0003] In order to cope with the floating state of the source of the upper bridge arm of the bridge arm circuit, an independent isolated power supply is usually used. In some low-power occasions, in order to improve power density and save costs, the gate of the upper bridge arm is usually powered by a bootstrap circuit.

[0004] Since the charging of the bootstrap voltage of the upper bridge arm depends on the opening of the lower bridge arm, the bootstrap voltage of the upper bridge arm often fluctuates greatly when the multi-phase bridge arm circuit performs power conversion. In addition, the upper bridge arm of the multi-phase bridge arm is turned on at different times, which will cause the bootstrap voltage of the multi-phase bridge arm to be unbalanced. The instability and imbalance of the bootstrap voltage can easily cause insufficient power supply for the gate drive of the bridge arm or even cause circuit failure. Utility Model Content

[0005] The present application provides a bootstrap circuit and an electronic circuit capable of stabilizing and balancing the bootstrap voltage of a multi-phase bridge arm.

[0006] In the first aspect, an embodiment of the present application provides a bootstrap circuit for an N-phase bridge arm circuit, where N is an integer greater than or equal to 2, and the bootstrap circuit includes: N bootstrap branches, which are connected one-to-one with the N bridge arms of the bridge arm circuit, each bootstrap branch includes a capacitor and a diode, and in the same bootstrap branch, one end of the capacitor is connected to the connection point of the upper and lower bridge arms in the bridge arm, the other end of the capacitor is connected to the cathode of the diode, and the anode of the diode is connected to the power supply; wherein, the diodes of at least two bootstrap branches are connected in parallel.

[0007] In a possible implementation manner of the first aspect, the bootstrap circuit further includes a first current limiting module, and the first current limiting module is connected between the anode of the diode and the power supply.

[0008] In a possible implementation manner of the first aspect, diodes of at least two bootstrap branches are connected to a power supply through a same first current limiting module.

[0009] In a possible implementation manner of the first aspect, the first current limiting module includes a first resistor.

[0010] In a possible implementation manner of the first aspect, N=3, and diodes of three bootstrap branches are connected in parallel.

[0011] Based on the same inventive concept, in a second aspect, an embodiment of the present application further provides an electronic circuit, comprising:

[0012] N-phase bridge arm circuit, N is an integer greater than or equal to 2;

[0013] And a bootstrap circuit as described in any embodiment of the first aspect.

[0014] In a possible implementation manner of the second aspect, the electronic circuit further includes a driving chip, and a driving pin of the driving chip is connected to the control end of the bridge arm circuit.

[0015] In a possible implementation manner of the second aspect, control ends of different bridge arms in the bridge arm circuit are connected to different driving chips.

[0016] In a possible implementation manner of the second aspect, the electronic circuit further includes a second current limiting module, and the second current limiting module is connected between the driving pin of the driving chip and the control end of the bridge arm.

[0017] In a possible implementation manner of the second aspect, the second current limiting module includes a second resistor.

[0018] According to the bootstrap circuit and electronic circuit provided by the embodiments of the present application, when the lower bridge arms of two or three phases are turned on at the same time, for multiple bootstrap branches connected in parallel with diodes, the diode can preferentially turn on a bootstrap branch with the lowest bootstrap voltage to charge the capacitor in the bootstrap branch with the lowest bootstrap voltage. At the same time, the diode has a clamping effect and can clamp the bootstrap voltage of the bootstrap branches connected in parallel with the diode to ensure that the bootstrap branch with the lowest bootstrap voltage is charged preferentially; then, the capacitor in the bootstrap branch with the second lowest bootstrap voltage is charged, and finally, the capacitor in the bootstrap branch with the highest bootstrap voltage is charged until the bootstrap voltages of the multiple bootstrap branches connected in parallel with diodes reach a consistent level, thereby achieving balance and stability of the bootstrap voltages of the multiple bootstrap branches connected in parallel with diodes, which helps to ensure the normal operation of the power conversion of the multi-phase bridge arm circuit.

[0019] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objects and advantages of the present application will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which the same or similar reference numerals represent the same or similar features and the accompanying drawings are not drawn to scale.

[0021] Figure 1 A schematic diagram showing a topological structure of a three-phase bridge arm circuit provided in an embodiment of the present application is shown;

[0022] Figure 2 A schematic diagram showing a topological structure of an electronic circuit provided in an embodiment of the present application is shown;

[0023] Figure 3 A timing diagram showing a bootstrap circuit provided in an embodiment of the present application to achieve bootstrap voltage balance;

[0024] Figure 4 A schematic diagram showing a current flow direction of a bootstrap circuit provided by an embodiment of the present application in a first time period;

[0025] Figure 5 A schematic diagram showing a current flow direction of a bootstrap circuit provided in an embodiment of the present application in a second time period;

[0026] Figure 6 A schematic diagram showing the current flow direction of the bootstrap circuit provided in an embodiment of the present application in a third time period is shown. DETAILED DESCRIPTION

[0027] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present application and are not configured to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by illustrating the examples of the present application.

[0028] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0029] It should be understood that when describing the structure of a component, when a layer or a region is referred to as being "on" or "over" another layer or another region, it may mean that it is directly on the other layer or another region, or that other layers or regions are included between it and the other layer or another region. Moreover, if the component is turned over, the layer or a region will be "below" or "beneath" another layer or another region.

[0030] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0031] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0032] It is obvious to those skilled in the art that various modifications and changes can be made in the present application without departing from the spirit or scope of the present application. Therefore, the present application is intended to cover modifications and changes of the present application that fall within the scope of the corresponding claims (technical solutions for protection) and their equivalents. It should be noted that the implementation methods provided in the embodiments of the present application can be combined with each other without contradiction.

[0033] In order to solve the problem of unstable and unbalanced bootstrap voltage of multi-phase bridge arms, related technologies have added hardware detection circuit designs, but this increases production costs, and the control is complex and impractical. There are also software algorithm controls. In order to ensure that the bootstrap voltage is maintained within a reasonable range, it is necessary to use regular or irregular pulses for charging, or to ensure that the lower bridge arm pulses are wide enough to charge the bootstrap capacitor regularly, which will reduce the utilization rate of the motor DC bus, reduce the working range of the bridge circuit, and make the control more complicated.

[0034] Based on this, the embodiments of the present application provide a bootstrap circuit and an electronic circuit. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0035] like Figure 1 and Figure 2 As shown, the bootstrap circuit 20 provided in the embodiment of the present application can be used for the N-phase bridge arm circuit 10, wherein N is an integer greater than or equal to 2. For example, N is 2, 3, 4, etc.

[0036] As an example, the bootstrap circuit of the present application can be used for Figure 1 The three-phase bridge arm circuit 10 shown in FIG. Figure 1 As shown, each bridge arm may include an upper bridge arm and a lower bridge arm, for example, the first bridge arm includes an upper bridge arm VT1 and a lower bridge arm VT2, the second bridge arm includes an upper bridge arm VT3 and a lower bridge arm VT4, and the third bridge arm includes an upper bridge arm VT5 and a lower bridge arm VT6. The connection point of the upper and lower bridge arms in the same bridge arm may be referred to as the midpoint of the bridge arm, wherein the connection point of the upper bridge arm VT1 and the lower bridge arm VT2 is marked as a, the connection point of the upper bridge arm VT3 and the lower bridge arm VT4 is marked as b, and the connection point of the upper bridge arm VT5 and the lower bridge arm VT6 is marked as c. In addition, a plurality of upper bridge arms (VT1, VT3, VT5) are connected to the first bus, and a plurality of lower bridge arms (VT2, VT4, VT6) are connected to the second bus.

[0037] Exemplarily, both the upper and lower bridge arms may include a switch tube. For example, the switch tube may be an insulated-gate bipolar transistor (IGBT).

[0038] It should be noted that, in order to facilitate the description of the bootstrap circuit of the present application, the three-phase bridge arm circuit is used as an example in the drawings of the present application, which is not used to limit the present application. It is understandable that the bootstrap circuit of the present application is applicable to bridge arm circuits with two or more phases.

[0039] like Figure 2As shown, the bootstrap circuit 20 includes N bootstrap branches 21, and the N bootstrap branches 21 are connected to the N bridge arms of the N-phase bridge arm circuit in a one-to-one correspondence. Each bootstrap branch includes a capacitor and a diode. In the same bootstrap branch, one end of the capacitor is connected to the connection point of the upper and lower bridge arms in one bridge arm, the other end of the capacitor is connected to the cathode of the diode, and the anode of the diode is connected to the power supply Vcc. Among them, the diodes of at least two bootstrap branches are connected in parallel.

[0040] For example, when N=2, the bootstrap circuit includes two bootstrap branches, and two diodes of the two bootstrap branches may be connected in parallel.

[0041] For another example, when N=3, the bootstrap circuit includes three bootstrap branches, and the two diodes in any two bootstrap branches can be connected in parallel, or the three diodes in the three bootstrap branches can be connected in parallel. It is understandable that N can also be other values, which are not listed one by one.

[0042] The capacitor and diode in the bootstrap branch are connected in series between the power supply Vcc and the connection point between the upper and lower bridge arms. In this way, the capacitor in the bootstrap branch can be charged when the lower bridge arm is turned on by utilizing the principle that the voltage across the capacitor cannot change suddenly, so as to ensure the size of the bootstrap voltage for supplying power to the gate source of the upper bridge arm. It can be understood that the capacitor in the bootstrap branch can be called a bootstrap capacitor, and the diode in the bootstrap branch can be called a bootstrap diode.

[0043] For example, Figure 2 In the example of N=3, capacitor C1 and diode D1 form a first bootstrap branch, capacitor C2 and diode D2 form a second bootstrap branch, capacitor C3 and diode D3 form a third bootstrap branch. Among the three bootstrap branches, diodes of at least two bootstrap branches can be connected in parallel.

[0044] When the multi-phase bridge arm circuit performs power conversion, the upper bridge arm is always turned on at different times, which will cause an unbalanced three-phase bootstrap voltage, that is, the voltage across the three-phase bootstrap capacitor always fluctuates greatly and is unbalanced.

[0045] In the bootstrap circuit provided in the embodiment of the present application, when the lower bridge arms of two or three phases are turned on at the same time, for multiple bootstrap branches connected in parallel with diodes, the diode can preferentially turn on the bootstrap branch with the lowest bootstrap voltage to charge the capacitor in the bootstrap branch with the lowest bootstrap voltage. At the same time, the diode has a clamping effect, and can clamp the bootstrap voltage of the bootstrap branches connected in parallel with the diode to ensure that the bootstrap branch with the lowest bootstrap voltage is charged preferentially; then, the capacitor in the bootstrap branch with the second lowest bootstrap voltage is charged, and finally, the capacitor in the bootstrap branch with the highest bootstrap voltage is charged, until the bootstrap voltages of the multiple bootstrap branches connected in parallel with diodes reach a consistent level, thereby achieving balance and stability of the bootstrap voltages of the multiple bootstrap branches connected in parallel with diodes, which helps to ensure the normal operation of the power conversion of the multi-phase bridge arm circuit.

[0046] As an example, when N=3, the diodes of the three bootstrap branches are connected in parallel. In this case, the upper bridge arm of the three-phase bridge arm circuit shares a power supply Vcc, the three-phase bootstrap diodes D1, D2, and D3 are connected in parallel, the positive poles of the three-phase bootstrap diodes D1, D2, and D3 are connected to the power supply Vcc, and the negative poles of the three-phase bootstrap diodes D1, D2, and D3 are connected to the bootstrap capacitors corresponding to each phase of the three-phase bridge arm circuit. In this way, the bootstrap voltage of each phase in the multi-phase bridge arm circuit can be balanced and stabilized.

[0047] The following combination Figures 3 to 6 To illustrate the working principle of the bootstrap circuit.

[0048] like Figure 3 As shown, u1, u2, and u3 are the initial voltage values ​​across the bootstrap capacitors C1, C2, and C3, respectively, Vcc is the voltage value of the bootstrap power supply, L1, L2, and L3 are the driving signals of the control end of the lower bridge arm of the three-phase bridge arm, respectively, taking the initial voltage u1 across the bootstrap capacitor C1 as the lowest, the initial voltage u2 across the bootstrap capacitor C2 as the moderate, and the initial voltage u3 across the bootstrap capacitor C3 as the highest as an example, and taking the simultaneous conduction of the three-phase lower bridge arms as an example. When the diode is turned on, the power supply Vcc preferentially charges the capacitor with the lowest bootstrap voltage (i.e., the bootstrap capacitor C1), and at this time, the bootstrap diodes D1, D2, and D3 corresponding to the three-phase bridge arm will be clamped to the voltage value across the bootstrap capacitor C1.

[0049] Figures 4 to 6 The dashed line with an arrow in the middle indicates the direction of current flow.

[0050] Figure 4 The current flow diagram of the bootstrap power supply in the first period (t1-t2) is given. The current only flows to the capacitor C1 to charge C1.

[0051] When the power supply Vcc charges the voltage across the bootstrap capacitor C1 to the voltage value u2 across the bootstrap capacitor C2, the power supply Vcc will charge the bootstrap capacitors C1 and C2 at the same time.

[0052] Figure 5 The current flow diagram of the bootstrap power supply in the second period (t2-t3) is given. The current flows to the capacitors C1 and C2 and charges the capacitors C1 and C2 at the same time.

[0053] When the power supply charges the voltage across the bootstrap capacitors C1 and C2 to the voltage u3 across the bootstrap capacitor C3, the power supply will charge the bootstrap capacitors C1, C2, and C3 simultaneously until the three capacitors are charged to a voltage close to or equal to the bootstrap power supply Vcc.

[0054] Figure 6 The current flow diagram of the third period (t3-t4) of the bootstrap power supply is given. The current flows to the capacitors C1, C2, and C3, and charges the capacitors C1, C2, and C3 at the same time.

[0055] It is understandable that when the bootstrap voltage of the three-phase bridge arm is unbalanced, since one end of the bootstrap capacitors C1, C2, and C3 corresponding to the three-phase bridge arm are connected together, the bootstrap voltage of the three-phase bridge arm can be self-balanced.

[0056] It can be seen that at least three-phase bootstrap diodes are connected in parallel in the bootstrap circuit provided in the embodiment of the present application. By utilizing the clamping effect of the diode, when the lower bridge arm is turned on, the bootstrap branch corresponding to the one-phase bridge arm with a lower bootstrap voltage can be charged first, so as to achieve the effect of balancing and stabilizing the bootstrap voltage of the multi-phase bridge arm circuit. In addition, the bootstrap circuit provided in the embodiment of the present application is simple to implement, without adding any control method, and improves the reliability of system operation; and simplifies the circuit, which can reduce the area of ​​the printed circuit board (PCB) and improve the power density of the system.

[0057] In the process of charging the capacitor of the bootstrap branch, a current flows between the bootstrap branch and the power supply. The magnitude of the current will affect the components in the circuit system.

[0058] In some embodiments, Figure 2 As shown, the bootstrap circuit 20 further includes a first current limiting module 22, and the first current limiting module 22 is connected between the anode of the diode and the power supply Vcc.

[0059] In the embodiment of the present application, by providing a first current limiting module, the current can be reasonably controlled to avoid damage to components due to excessive current, thereby improving the reliability of the circuit.

[0060] In the process of charging the capacitor of the bootstrap branch, if the charging current is too small, the charging efficiency will be affected.

[0061] As an example, Figure 2 As shown, the diodes of at least two bootstrap branches 21 are connected to the power supply Vcc through the same first current limiting module 22. In other words, at least two bootstrap branches 21 can share a first current limiting module 22. For example, for a three-phase bridge arm circuit, three bootstrap branches 21 corresponding to the three-phase bridge arm can share the same first current limiting module 22. In this way, the number of first current limiting modules can be reduced, which is conducive to simplifying the circuit and reducing the PCB area; in addition, when the power supply generates the same stress, a larger charging current can be provided, thereby improving the charging efficiency.

[0062] It is understandable that in other examples, it can also be designed according to the needs: multiple bootstrap branches can use different first current limiting modules respectively. In other words, different bootstrap branches may not share the same first current limiting module. For example, for a three-phase bridge arm circuit, the three-phase bridge arm corresponds to three bootstrap branches 21, and three first current limiting modules can be provided. For each first current limiting module, its first end is connected to the positive electrode of one of the diodes, and its second end is connected to the power supply.

[0063] In some embodiments, Figure 2 As shown, the first current limiting module 22 of the embodiment of the present application may include a first resistor R1. The current limiting is achieved by the first resistor, which is relatively simple in structure.

[0064] For example, for a three-phase bridge arm circuit, the three bootstrap branches 21 corresponding to the three-phase bridge arm can share the same first resistor R1. When the power supply produces the same stress (stress can be understood as driving capability), using one resistor for each bootstrap branch 21 can reduce the current limiting resistance to 1 / 3 and provide a larger charging current to improve the charging efficiency.

[0065] It should be noted that using the first resistor to limit current is only an example, and alternative solutions based on using a resistor to limit current are all within the protection scope of this application.

[0066] Based on the same inventive concept, the present application embodiment also provides an electronic circuit. Figure 2 As shown, the electronic circuit of the embodiment of the present application includes an N-phase bridge arm circuit 10, where N is an integer greater than or equal to 2; and a bootstrap circuit 20 as introduced in any of the above embodiments.

[0067] The display panel provided in the embodiment of the present application has the beneficial effects of the pixel driving circuit provided in the embodiment of the present application. For details, please refer to the specific description of the pixel driving circuit in the above embodiments, which will not be repeated in this embodiment.

[0068] In some embodiments, as shown in Figure 2, the electronic circuit provided in the embodiment of the present application further includes a driving chip, and the driving pin of the driving chip is connected to the control end of the bridge arm circuit. The control end of the bridge arm circuit refers to the gate of the transistor of the bridge arm.

[0069] As described above, each bridge arm may include an upper bridge arm and a lower bridge arm, and the upper bridge arm and the lower bridge arm are connected to different driving pins of the driver chip. In addition, the upper bridge arms of different bridge arms are connected to different driving pins of the driver chip, and the lower bridge arms of different bridge arms are connected to different driving pins of the driver chip.

[0070] The driving pin of the driving chip can provide a driving signal to control whether the upper and lower bridge arms are turned on. For example, the driving signals H1, H2, and H3 are used to control the states of the upper bridge arms VT1, VT3, and VT5, respectively, and the driving signals L1, L2, and L3 are used to control the states of the lower bridge arms VT2, VT4, and VT6, respectively.

[0071] Exemplarily, the driving signals H1 , H2 , H3 and the driving signals L1 , L2 , L3 may be pulse width modulation (PWM) signals, where a PWM signal is a signal with alternating high and low levels.

[0072] The N-phase bridge arm circuit includes multiple bridge arms, each of which requires a driver chip for driving control. In some embodiments, the control ends of different bridge arms in the bridge arm circuit are connected to different driver chips. In other words, different driver chips can be used to drive and control different bridge arms.

[0073] For example, for a three-phase bridge arm circuit, three driver chips may be provided. Driver chip 1 is connected to the first bridge arm, and driver chip 1 provides a drive signal H1 to drive the gate of the upper bridge arm VT1, and driver chip 1 provides a drive signal L1 to drive the lower bridge arm VT2. Driver chip 2 is connected to the second bridge arm, and driver chip 2 provides a drive signal H2 to drive the gate of the upper bridge arm VT3, and driver chip 2 provides a drive signal L2 to drive the lower bridge arm VT4. Driver chip 3 is connected to the third bridge arm, and driver chip 3 provides a drive signal H3 to drive the gate of the upper bridge arm VT5, and driver chip 3 provides a drive signal L3 to drive the lower bridge arm VT6.

[0074] In the embodiment of the present application, different bridge arms are driven by different driver chips, which can improve the flexibility of controlling different bridge arms; in addition, when one of the driver chips is damaged or abnormal, only the damaged or abnormal driver chip can be replaced, which is conducive to reducing maintenance costs.

[0075] It is understandable that in other examples, it can also be designed according to the needs that: multiple bridge arms are connected to the same driver chip. In other words, one driver chip is used to drive different bridge arms. For example, for a three-phase bridge arm circuit, the same driver chip can be integrated with six drive pins, and the six drive pins are used to provide drive signals H1, H2, H3 and drive signals L1, L2, L3 respectively.

[0076] It should be noted that the embodiments of the present application do not limit the specific structure, model, etc. of the driver chip.

[0077] In some embodiments, Figure 2 As shown, the electronic circuit may further include a second current limiting module 32, which is connected between the driving pin of the driving chip and the control end of the bridge arm. In the embodiment of the present application, by providing the second current limiting module, the current can be reasonably controlled to avoid damage to components due to excessive current, thereby improving the reliability of the circuit.

[0078] Exemplarily, a second current limiting module 32 may be connected between each upper bridge arm and a driving pin of the driving chip, and a second current limiting module 32 may be connected between each lower bridge arm and a driving pin of the driving chip.

[0079] In some embodiments, Figure 2 As shown, the second current limiting module 32 of the embodiment of the present application may include a second resistor. For easy distinction, the second resistor connected to the upper bridge arm VT1 in the first bridge arm is marked as R g1 The second resistor connected to the lower bridge arm VT2 in the first bridge arm is marked as R g2 The second resistor connected to the upper bridge arm VT3 in the second bridge arm is marked as R g3 The second resistor connected to the lower bridge arm VT4 in the second bridge arm is marked as R g4 The second resistor connected to the upper bridge arm VT5 in the third bridge arm is marked as R g5 The second resistor connected to the lower bridge arm VT6 in the third bridge arm is marked as R g6 The embodiment of the present application realizes current limiting through the second resistor, and the structure is relatively simple.

[0080] It should be noted that using the second resistor to limit the current is only an example, and alternative solutions based on using a resistor to limit the current are all within the protection scope of this application.

[0081] In addition, it should be noted that in the embodiments shown in the above figures, the resistor is represented by a single resistor, the capacitor is represented by a single capacitor, and the diode is represented by a single diode. In other embodiments, the resistor may be an integration of resistors connected in series, in parallel, or in a mixed connection, the capacitor may be an integration of capacitors connected in series, in parallel, or in a mixed connection, and the diode may be an integration of diodes connected in series, in parallel, or in a mixed connection.

[0082] In addition, the specific parameters of each component can be set according to actual needs, and this application does not limit this.

[0083] According to the embodiments described above in the present application, these embodiments do not describe all the details in detail, nor do they limit the present application to the specific embodiments described. Obviously, many modifications and changes can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can make good use of the present application and the modifications based on the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A bootstrap circuit, characterized in that: For an N-phase bridge arm circuit, where N is an integer greater than or equal to 2, the bootstrap circuit comprises: N bootstrap branches are connected to the N bridge arms of the bridge arm circuit in a one-to-one correspondence, each of the bootstrap branches includes a capacitor and a diode, and in the same bootstrap branch, one end of the capacitor is connected to the connection point of the upper and lower bridge arms in the bridge arm, the other end of the capacitor is connected to the cathode of the diode, and the anode of the diode is connected to a power supply; Wherein, the diodes of at least two of the bootstrap branches are connected in parallel.

2. The bootstrap circuit according to claim 1, characterized in that The bootstrap circuit further includes a first current limiting module, which is connected between the anode of the diode and the power supply.

3. The bootstrap circuit according to claim 2, characterized in that: The diodes of at least two of the bootstrap branches are connected to the power supply through the same first current limiting module.

4. The bootstrap circuit according to claim 2 or 3, characterized in that: The first current limiting module includes a first resistor.

5. The bootstrap circuit according to any one of claims 1 to 3, characterized in that: N=3, and the diodes of the three bootstrap branches are connected in parallel.

6. An electronic circuit, characterized in that: include: N-phase bridge arm circuit, N is an integer greater than or equal to 2; And the bootstrap circuit as claimed in any one of claims 1 to 5.

7. The electronic circuit according to claim 6, characterized in that The electronic circuit also includes a driving chip, and a driving pin of the driving chip is connected to the control end of the bridge arm circuit.

8. The electronic circuit according to claim 7, characterized in that The control ends of different bridge arms in the bridge arm circuit are connected to different driving chips.

9. The electronic circuit according to claim 7 or 8, characterized in that: The electronic circuit further includes a second current limiting module, which is connected between the driving pin of the driving chip and the control end of the bridge arm.

10. The electronic circuit according to claim 9, characterized in that The second current limiting module includes a second resistor.

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