Novel RCD voltage-sharing circuit

Abstract

The utility model discloses a novel RCD voltage-sharing circuit, which comprises a voltage-sharing IGBT, a static voltage-sharing circuit and a dynamic voltage-sharing circuit, the static voltage-sharing circuit comprises a first resistor and a second resistor, the first resistor and the second resistor are connected in parallel at two ends of the voltage-sharing IGBT, and the resistance value of the first resistor is greater than that of the second resistor; the dynamic voltage-sharing circuit comprises a first capacitor, a second capacitor and an auxiliary IGBT, the first capacitor and the second capacitor are connected in series, the auxiliary IGBT and the second capacitor are connected in parallel, and the capacitance value of the first capacitor is larger than that of the second capacitor; when the voltage at the two ends of the voltage-sharing IGBT exceeds a preset threshold value, the voltage on the second resistor is correspondingly increased, and after the voltage reaches a turn-on threshold value of the auxiliary IGBT, the auxiliary IGBT is triggered to be turned on, so that the second capacitor is short-circuited, and only the first capacitor independently undertakes a voltage-sharing task. Through the combination of the static voltage-sharing circuit and the dynamic voltage-sharing circuit, the contradiction between the voltage-sharing effect and the turn-off speed in the traditional RCD voltage-sharing circuit is effectively solved, so that the voltage-sharing IGBT is high in turn-off speed and small in loss.

Description

Technical Field

[0001] This utility model relates to the field of high voltage DC circuit breaker technology, and in particular to a novel RCD voltage equalization circuit. Background Technology

[0002] In high-voltage DC circuit breakers, multiple insulated-gate bipolar transistors (IGBTs) are typically connected in series to achieve high-power switching functionality. However, due to issues such as manufacturing processes, parameter differences, and drive signal synchronization, uneven voltage distribution can easily occur during the turn-off process of series-connected IGBTs. This can cause some IGBTs to experience excessive voltage stress, affecting their reliability and lifespan.

[0003] While traditional RCD (resistor-capacitor-diode) voltage equalization circuits can solve this problem to some extent, the presence of capacitors means that the voltage equalization effect of the IGBT and the turn-off time will always be a trade-off. If the capacitor value is large, the voltage equalization effect can be guaranteed, but the turn-off time will be long, and the increased turn-off losses will become a new problem; conversely, if the capacitor value is small, the IGBT turn-off time will be short and the losses will be low, but the voltage equalization effect will be difficult to guarantee. Utility Model Content

[0004] Therefore, it is necessary to provide a novel RCD voltage equalization circuit to address the aforementioned technical problems.

[0005] To achieve the above objectives, this utility model provides a novel RCD voltage equalization circuit, comprising:

[0006] At least one voltage-equalizing IGBT is installed in the main circuit of the high-voltage DC circuit breaker to control the on / off of high-voltage DC power.

[0007] The static voltage equalization circuit includes a first resistor and a second resistor, which are connected in parallel across the voltage equalization IGBT, wherein the resistance of the first resistor is greater than that of the second resistor.

[0008] The dynamic voltage equalization circuit includes a first capacitor, a second capacitor, and an auxiliary IGBT. The first capacitor and the second capacitor are connected in series, and the auxiliary IGBT is connected in parallel with the second capacitor. The capacitance value of the first capacitor is greater than the capacitance value of the second capacitor.

[0009] In this configuration, the second resistor serves as an overvoltage detection resistor, and the auxiliary IGBT acts as a short-circuit switch for the second capacitor. When the voltage across the voltage equalization IGBT exceeds a preset threshold, the voltage across the second resistor also increases accordingly. Once the turn-on threshold of the auxiliary IGBT is reached, the auxiliary IGBT is triggered to conduct, causing the second capacitor to be short-circuited, leaving only the first capacitor to handle the voltage equalization task.

[0010] Preferably, the capacitance of the first capacitor is 5 to 6 times the capacitance of the second capacitor.

[0011] Preferably, it further includes an absorption circuit consisting of a third resistor and a diode, wherein: the third resistor is connected in series with the first capacitor and the second capacitor; the diode is connected in parallel with the third resistor; the absorption circuit is used to absorb the reverse voltage spike generated during the turn-off process of the voltage equalization IGBT and protect the voltage equalization IGBT.

[0012] Preferably, at least two voltage-equalizing IGBTs are installed in the main circuit of the high-voltage DC circuit breaker, and the voltage-equalizing IGBTs are connected in series in the main circuit of the high-voltage DC circuit breaker.

[0013] The beneficial effects of this technical solution are: by combining static and dynamic voltage equalization circuits, the contradiction between voltage equalization effect and turn-off speed in traditional RCD voltage equalization circuits is effectively solved, resulting in fast turn-off speed and low loss of voltage equalization IGBT. Attached Figure Description

[0014] Figure 1 This is a circuit diagram of a novel RCD voltage equalization circuit according to an embodiment of the present invention.

[0015] Figure 2 The circuit diagram is for an existing RCD voltage equalization circuit. Detailed Implementation

[0016] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0017] Please see Figure 1 and Figure 2 , Figure 1 In the diagram, Z1 is the voltage equalizing IGBT, Z3 is the auxiliary IGBT, R11 is the first resistor, R12 is the second resistor, C11 is the first capacitor, C12 is the second capacitor, R13 is the third resistor, and D is the diode. Figure 2 In the diagram, IGBT1, IGBT2, IGBT3, and IGBT4 are all IGBTs connected in series in the main circuit of the high-voltage DC circuit breaker. R and Rs are resistors, C is a capacitor, and D is a diode.

[0018] Please see Figure 1 This application provides a novel RCD voltage equalization circuit, including at least one voltage equalization IGBT Z1, a static voltage equalization circuit, a dynamic voltage equalization circuit, and an absorption circuit.

[0019] The equalizing IGBT Z1 is installed in the main circuit of the high-voltage DC circuit breaker to control the switching on and off of the high-voltage DC power. Generally, at least two equalizing IGBT Z1s are installed in the main circuit of the high-voltage DC circuit breaker, and the equalizing IGBT Z1s are connected in series in the main circuit of the high-voltage DC circuit breaker.

[0020] The static voltage equalization circuit includes a first resistor R11 and a second resistor R12, which are connected in parallel across the voltage equalization IGBT Z1. The resistance of the first resistor R11 is greater than that of the second resistor R12. Specifically, the resistance of R11 can be set to 5 to 10 times that of R12.

[0021] The dynamic voltage equalization circuit includes a first capacitor C11, a second capacitor C12, and an auxiliary IGBT Z3. The first capacitor C11 and the second capacitor C12 are connected in series, and the auxiliary IGBT Z3 is connected in parallel with the second capacitor C12. The capacitance value of the first capacitor C11 is greater than the capacitance value of the second capacitor C12. The size of the first capacitor C11 and the second capacitor C12 can be determined by judging the magnitude of the overvoltage.

[0022] The second resistor R12 acts as an overvoltage detection resistor, and the auxiliary IGBT Z3 acts as a short-circuit switch for the second capacitor C12. When the voltage across the voltage-equalizing IGBT Z1 exceeds a preset threshold, the voltage across the second resistor R12 also increases accordingly. Once the turn-on threshold of the auxiliary IGBT Z3 is reached, it triggers the auxiliary IGBT Z3 to conduct, short-circuiting the second capacitor C12, leaving only the first capacitor C11 to handle the voltage equalization task. The capacitance value of the first capacitor C11 can be set to 5 to 6 times the capacitance value of the second capacitor C12, specifically 5 or 6 times. Increasing the capacitance value of the voltage equalization circuit will improve the voltage equalization effect. This allows for load-side autonomous selection of the voltage equalization capacitor value.

[0023] When the voltage equalization effect of the series-connected voltage equalization IGBT Z1 is good, the voltage on the second resistor R12 used for static voltage equalization is also small, which is insufficient to trigger the conduction of the auxiliary IGBT Z3. At this time, the two capacitors, the first resistor R11 and the second resistor R12, work together to participate in voltage equalization. The capacitance value of the voltage equalization circuit is small, the voltage equalization IGBT Z1 has a fast switching speed and low loss.

[0024] The turn-on threshold setting for the auxiliary IGBT Z3 should be slightly higher than the maximum voltage value that may occur on R12 under normal operating conditions.

[0025] The absorption circuit consists of a third resistor R13 and a diode D. The third resistor R13 is connected in series with the first capacitor C11 and the second capacitor C12. The diode D is connected in parallel with the third resistor R13 and is used to limit the direction of current. The absorption circuit is used to absorb the reverse voltage spike generated during the turn-off process of the equalizing IGBT Z1 and protect the equalizing IGBT Z1.

[0026] By combining static and dynamic voltage equalization circuits, the contradiction between voltage equalization effect and turn-off speed in traditional RCD voltage equalization circuits is effectively resolved, thereby improving the reliability and service life of series IGBTs.

[0027] It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

[0028] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0029] 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 indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

Claims

1. A novel RCD voltage equalization circuit, characterized in that: include: At least one equalizing IGBT (Z1) is installed in the main circuit of the high-voltage DC circuit breaker to control the on / off of high-voltage DC power. The static voltage equalization circuit includes a first resistor (R11) and a second resistor (R12). The first resistor (R11) and the second resistor (R12) are connected in parallel across the voltage equalization IGBT (Z1), wherein the resistance of the first resistor (R11) is greater than that of the second resistor (R12). The dynamic voltage equalization circuit includes a first capacitor (C11), a second capacitor (C12), and an auxiliary IGBT (Z3). The first capacitor (C11) and the second capacitor (C12) are connected in series, and the auxiliary IGBT (Z3) is connected in parallel with the second capacitor (C12). The capacitance value of the first capacitor (C11) is greater than the capacitance value of the second capacitor (C12). In this circuit, the second resistor (R12) serves as an overvoltage detection resistor, and the auxiliary IGBT (Z3) acts as a short-circuit switch for the second capacitor (C12). When the voltage across the voltage equalizing IGBT (Z1) exceeds a preset threshold, the voltage across the second resistor (R12) also increases accordingly. Once the turn-on threshold of the auxiliary IGBT (Z3) is reached, the auxiliary IGBT (Z3) is triggered to conduct, causing the second capacitor (C12) to be short-circuited, leaving only the first capacitor (C11) to handle the voltage equalization task.

2. The novel RCD voltage equalization circuit according to claim 1, characterized in that, The capacitance of the first capacitor (C11) is 5 to 6 times the capacitance of the second capacitor (C12).

3. The novel RCD voltage equalization circuit according to claim 1, characterized in that, It also includes an absorption circuit consisting of a third resistor (R13) and a diode (D), wherein: the third resistor (R13) is connected in series with the first capacitor (C11) and the second capacitor (C12); and the diode (D) is connected in parallel with the third resistor (R13).

4. The novel RCD voltage equalization circuit according to claim 1, characterized in that, At least two equalizing IGBTs (Z1) are installed in the main circuit of the high-voltage DC circuit breaker, and the equalizing IGBTs (Z1) are connected in series in the main circuit of the high-voltage DC circuit breaker.

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