Peak voltage absorption circuit and converter circuit

Abstract

The peak voltage absorption circuit comprises a peak voltage absorption module and a capacitive element, the peak voltage absorption module is connected with the capacitive element in parallel, the peak voltage absorption module is used for adjusting the magnitude of clamping voltage based on the voltage stabilization principle, high-precision adjustment of the clamping voltage can be achieved, and the voltage stabilization effect is good. Therefore, efficient and low-cost peak voltage suppression is realized through an active absorption mode, and compared with the prior art, a control circuit does not need to be additionally arranged, the circuit structure is simplified, the component cost and the production cost are reduced, and higher economical efficiency and practicability are achieved.

Description

Technical Field

[0001] This utility model relates to the field of converter circuit protection technology, and in particular to a spike voltage absorption circuit and a converter circuit. Background Technology

[0002] In converter circuits, high voltage spikes occur in switching devices such as MOSFETs during turn-off, leading to significantly higher voltage stress requirements for these devices. To suppress voltage spikes and reduce voltage stress on switching devices, traditional solutions primarily employ RCD snubber circuits and active clamping circuits. However, these traditional solutions still have the following technical drawbacks: the relatively simple RCD snubber circuits used in the past have uncontrollable peak voltage values ​​and large voltage fluctuations, failing to effectively reduce voltage stress on the main switching transistor; the traditional active clamping circuits used to absorb voltage spikes are complex, requiring additional control circuitry and resulting in high production costs. Utility Model Content

[0003] The purpose of this invention is to solve the technical problem that existing converter circuits cannot effectively reduce the voltage stress of the main switching transistor and have high production costs, and to propose a spike voltage absorption circuit and converter circuit.

[0004] The technical problem of this utility model is solved by the following technical solution:

[0005] A spike voltage absorption circuit includes a spike voltage absorption module and a capacitive element, wherein the spike voltage absorption module and the capacitive element are connected in parallel, and the spike voltage absorption module is used to adjust the level of the clamping voltage based on the voltage regulation principle.

[0006] In some embodiments, the following technical features are also included:

[0007] The peak voltage absorption module includes a Zener diode and a bipolar transistor, and the capacitive element includes a first capacitor. The positive terminal of the Zener diode is electrically connected to the base of the bipolar transistor, and the negative terminal of the Zener diode is electrically connected to the collector of the bipolar transistor. One end of the first capacitor is electrically connected between the negative terminal of the Zener diode and the collector of the bipolar transistor, and the other end of the first capacitor is electrically connected to the emitter of the bipolar transistor.

[0008] In some embodiments, the device further includes a first resistor and a second resistor; one end of the first capacitor is connected between the first resistor and the second resistor, the first capacitor is electrically connected to the negative terminal of the Zener diode via the first resistor, and the first capacitor is electrically connected to the collector of the bipolar transistor via the second resistor.

[0009] This utility model also provides the following technical solution:

[0010] A converter circuit includes a transformer, a primary circuit of the transformer, a secondary circuit of the transformer, and the aforementioned spike voltage absorption circuit. The spike voltage absorption circuit, the primary circuit of the transformer, and one side of the transformer are electrically connected in sequence, and the other side of the transformer is electrically connected to the secondary circuit of the transformer.

[0011] In some embodiments, the primary circuit of the transformer includes a first rectifier diode, a first switching transistor, and a second capacitor. The anode of the first rectifier diode is electrically connected to the drain of the first switching transistor and one side of the transformer. The cathode of the first rectifier diode is electrically connected to one end of the first capacitor, the cathode of the Zener diode, and the collector of the bipolar transistor. The source of the first switching transistor is grounded. One end of the second capacitor is electrically connected to the current input terminal, the other end of the first capacitor, and the emitter of the bipolar transistor. The other end of the second capacitor is grounded.

[0012] In some embodiments, the primary circuit of the transformer includes a first inductor, a second inductor, a first rectifier diode, a second rectifier diode, a second capacitor, a first switching transistor, and a second switching transistor. One end of the first inductor and the second inductor are both electrically connected to the current input terminal. The other end of the first inductor is both electrically connected to the anode of the first rectifier diode, one side of the transformer, and the drain of the first switching transistor. The other end of the second inductor is both electrically connected to the anode of the second rectifier diode, one side of the transformer, and the drain of the second switching transistor.

[0013] In some embodiments, the secondary circuit of the transformer includes a third rectifier diode and a third capacitor. The positive terminal of the third rectifier diode is electrically connected to the other side of the transformer, the negative terminal of the third rectifier diode is electrically connected to one end of the third capacitor, and the other end of the third capacitor is electrically connected to the other side of the transformer, the zero potential terminal.

[0014] In some embodiments, the transformer secondary circuit includes a third rectifier diode, a fourth rectifier diode, a fifth rectifier diode, a sixth rectifier diode, and a third capacitor. The anode of each third rectifier diode is electrically connected to the other side of the transformer and the cathode of the fourth rectifier diode. The cathode of each third rectifier diode is electrically connected to the cathode of the fifth rectifier diode, the third capacitor, and the current output terminal. The anode of each fourth rectifier diode is electrically connected to the anode of the sixth rectifier diode, the other end of the third capacitor, and the zero potential terminal. The anode of each fifth rectifier diode is electrically connected to the other side of the transformer and the cathode of the sixth rectifier diode.

[0015] The beneficial effects of this utility model compared with the prior art include:

[0016] The spike voltage absorption circuit and converter circuit proposed in this utility model, through the setting of spike voltage absorption modules and capacitive components in parallel, can achieve high-precision adjustment of clamping voltage based on the voltage regulation principle. Thus, it achieves efficient and low-cost spike voltage suppression through active absorption. Compared with the prior art, it does not require an external control circuit, simplifies the circuit structure, reduces component costs and production costs, and has higher economic efficiency and practicality.

[0017] In addition, some embodiments also have the following beneficial effects:

[0018] This invention utilizes a peak voltage absorption module comprising a Zener diode and a bipolar transistor, with a first capacitor as a capacitive element. The Zener diode's positive terminal is electrically connected to the base of the bipolar transistor, and its negative terminal is electrically connected to the collector of the bipolar transistor. One end of the first capacitor is electrically connected between the negative terminal of the Zener diode and the collector of the bipolar transistor, while the other end of the first capacitor is electrically connected to the emitter of the bipolar transistor. These features enable high-precision adjustment of the clamping voltage using the Zener diode and the transistor's amplification principle, thereby significantly enhancing both energy absorption efficiency and peak voltage absorption capability.

[0019] Other beneficial effects of the embodiments of this utility model will be further described below. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the spike voltage absorption circuit in an embodiment of this utility model;

[0021] Figure 2 This is a diagram of the spike voltage absorption circuit using an NPN transistor in an embodiment of this utility model;

[0022] Figure 3 This is a diagram of a spike voltage absorption circuit using a PNP transistor in another embodiment of this utility model;

[0023] Figure 4 This is another peak voltage absorption circuit diagram using an NPN transistor in this embodiment of the present invention;

[0024] Figure 5 This is another example of a spike voltage absorption circuit using a PNP transistor in this utility model embodiment;

[0025] Figure 6 This is a converter circuit diagram including a spike voltage absorption circuit in an embodiment of this utility model;

[0026] Figure 7 This is another converter circuit diagram including a spike voltage absorption circuit in an embodiment of this utility model. Detailed Implementation

[0027] The embodiments of this utility model are 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 this utility model.

[0028] 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 this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0029] In existing switching power converter circuits, power MOSFETs and other switching devices generate significant voltage spikes during turn-off. This phenomenon mainly stems from the energy conversion between parasitic inductance and capacitance in the circuit, leading to transient overvoltages across the switching devices. Excessively high voltage spikes not only increase the voltage stress on the switching devices, affecting their reliability and lifespan, but can also cause device breakdown and damage. Traditional solutions, primarily employing RCD snubber circuits and active clamping circuits, still suffer from the following drawbacks:

[0030] 1. Regarding the RCD absorption circuit:

[0031] (1) The peak voltage suppression effect is limited, and the peak value of the output voltage is uncontrollable;

[0032] (2) The parameters of the absorption circuit are fixed and cannot adapt to voltage fluctuations caused by load changes;

[0033] (3) The energy dissipation efficiency is low, and it cannot effectively reduce the voltage stress of the main switch.

[0034] 2. Regarding active clamping circuits:

[0035] (1) The circuit topology is complex and requires additional control circuitry;

[0036] (2) The large number of components leads to a significant increase in production costs;

[0037] (3) Strict timing control requirements increase the difficulty of system design.

[0038] To address the shortcomings of existing technologies, this utility model provides a peak voltage absorption circuit, including a peak voltage absorption module and a capacitive element, wherein the peak voltage absorption module and the capacitive element are connected in parallel, such as... Figure 1 As shown in the figure. Among them, the spike voltage absorption module is used to adjust the clamping voltage between points A and B.

[0039] In one embodiment, such as Figure 2and Figure 3 As shown, the peak voltage absorption module includes a Zener diode ZD1 and a bipolar transistor BG1, and a capacitive component including a first capacitor C2. The positive terminal of the Zener diode ZD1 is electrically connected to the base of the bipolar transistor BG1, and the negative terminal of the Zener diode ZD1 is electrically connected to the collector of the bipolar transistor BG1. One end of the first capacitor C2 is electrically connected between the negative terminal of the Zener diode ZD1 and the collector of the bipolar transistor BG1, and the other end of the first capacitor C2 is electrically connected to the emitter of the bipolar transistor BG1. Preferably, the bipolar transistor BG1 is an NPN or PNP type transistor. The working principle of the peak voltage absorption circuit in this embodiment is as follows:

[0040] The spike voltage absorption circuit provided in this embodiment uses the voltage regulation principle of a Zener diode to control the turn-on voltage of the power transistor. When a first capacitor C2 is connected between points A and B, it smooths the energy generated by the spike voltage at points A and B. When the voltage at points A and B is higher than the breakdown voltage of the Zener diode ZD1, the breakdown current flows through the Zener diode ZD1 and turns on the bipolar transistor BG1, clamping the voltage at points A and B slightly higher than the voltage of the Zener diode (0.7V). By selecting a suitable Zener diode, the clamping voltage can be adjusted. Figure 2 As shown, an NPN transistor can be used. Similarly, the same effect can be achieved using different types of PNP transistors, such as... Figure 3 As shown.

[0041] In another embodiment, such as Figure 4 and Figure 5 As shown, the peak voltage absorption module also includes a first resistor R1 and a second resistor R2; one end of the first capacitor C2 is connected between the first resistor R1 and the second resistor R2, the first capacitor C2 is electrically connected to the negative terminal of the Zener diode ZD1 through the first resistor R1, and the first capacitor C2 is electrically connected to the collector of the bipolar transistor BG1 through the second resistor R2. Preferably, the bipolar transistor BG1 is an NPN type transistor or a PNP type transistor.

[0042] This utility model embodiment also provides a converter circuit, including a transformer, a transformer primary circuit, a transformer secondary circuit, and the aforementioned spike voltage absorption circuit. The spike voltage absorption circuit, the transformer primary circuit, and one side of the transformer are electrically connected in sequence, and the other side of the transformer is electrically connected to the transformer secondary circuit.

[0043] In a preferred embodiment, such as Figure 6As shown, the converter circuit is applied to a flyback converter. The primary circuit of the transformer includes a first rectifier diode D5, a first switching transistor Q1, and a second capacitor C1. The anode of the first rectifier diode D5 is electrically connected to the drain of the first switching transistor Q1 and one side of the transformer T1. The cathode of the first rectifier diode D5 is electrically connected to one end of the first capacitor C2, the cathode of the Zener diode ZD1, and the collector of the bipolar transistor BG1. The source of the first switching transistor Q1 is grounded. One end of the second capacitor C1 is electrically connected to the current input terminal, the other end of the first capacitor C2, and the emitter of the bipolar transistor BG1. The other end of the second capacitor C1 is grounded. The secondary circuit of the transformer includes a third rectifier diode D2 and a third capacitor C3. The anode of the third rectifier diode D2 is electrically connected to the other side of the transformer T1. The cathode of the third rectifier diode D2 is electrically connected to one end of the third capacitor C3. The other end of the third capacitor C3 is electrically connected to the other side of the transformer T1 and the zero-potential terminal 0V. The working principle of the converter circuit in this embodiment is as follows:

[0044] When the switching transistor Q1 is turned off, the drain voltage of Q1 rises, and a transient spike is generated due to the inductive load. After the spike voltage is smoothed by the filter circuit composed of diode D5 and the first capacitor C2, if the spike voltage exceeds the preset voltage between points A and B in this embodiment (determined by the breakdown voltage of Zener diode ZD1), then bipolar transistor BG1 will conduct and consume excess power to adjust the potentials of points A and B to the critical value, thereby clamping the voltages of points A and B.

[0045] In another preferred embodiment, such as Figure 7As shown, the converter circuit is applied to a BOOST-push-pull converter. The primary circuit of the transformer includes a first inductor L1, a second inductor L2, a first rectifier diode D5, a second rectifier diode D6, a second capacitor C1, a first switch Q1, and a second switch Q2. One end of the first inductor L1 and the second inductor L2 are both electrically connected to the current input terminal. The other end of the first inductor L1 is electrically connected to the positive terminal of the first rectifier diode D5, one side of the transformer T1, and the drain of the first switch Q1. The other end of the second inductor L2 is electrically connected to the positive terminal of the second rectifier diode D6, one side of the transformer T1, and the drain of the second switch Q2. The transformer secondary circuit includes a third rectifier diode D1, a fourth rectifier diode D3, a fifth rectifier diode D2, a sixth rectifier diode D4, and a third capacitor C3. The positive terminal of the third rectifier diode D1 is electrically connected to the other side of the transformer and the negative terminal of the fourth rectifier diode D3. The negative terminal of the third rectifier diode D1 is electrically connected to the negative terminal of the fifth rectifier diode D2, the third capacitor C3, and the current output terminal (output). The positive terminal of the fourth rectifier diode D3 is electrically connected to the positive terminal of the sixth rectifier diode D4, the other end of the third capacitor C3, and the zero potential terminal (0V). The positive terminal of the fifth rectifier diode D2 is electrically connected to the other side of the transformer T1 and the negative terminal of the sixth rectifier diode D4. The working principle of the converter circuit in this embodiment is as follows:

[0046] When the voltage spikes generated across switching transistors Q1 and Q2 exceed the preset voltage between points A and B (the preset voltage is determined by the breakdown voltage of Zener diode ZD1), Zener diode ZD1 enters the conducting state. After Zener diode ZD1 is turned on, the current in Zener diode ZD1 flows through the base to the emitter of bipolar transistor BG1. Transistor BG1 consumes electrical energy to pull the potentials at points A and B back to the critical point, thereby clamping the voltages at points A and B.

[0047] Traditional RCD snubber circuits suffer from uncontrollable clamping voltage, while other active clamping circuits, although adjustable in voltage, require additional control circuitry and are costly. The spike voltage snubber circuit and converter circuit provided in this embodiment are based on the Zener diode's voltage regulation principle and the transistor's amplification principle, innovatively achieving active snubber functionality. This active snubber method enables efficient and low-cost spike voltage suppression. Compared to traditional solutions, the spike voltage snubber circuit in this embodiment has the following significant advantages:

[0048] Significantly enhanced absorption capacity: The peak voltage absorption circuit in this embodiment adopts a clamping structure combining a Zener diode and a transistor, which can precisely control the clamping voltage and achieve high-precision adjustment of the clamping voltage. This not only improves the energy absorption efficiency but also significantly enhances the peak voltage absorption capacity, thereby effectively suppressing voltage fluctuations and improving system stability.

[0049] Significant cost advantages: Unlike existing active clamping circuit solutions that require additional drive control circuits, the spike voltage absorption circuit in this embodiment does not require an external control circuit, simplifying the circuit structure, reducing component and production costs, and thus offering greater economic efficiency and practicality.

[0050] Wide applicability: The spike voltage absorption circuit in this embodiment is particularly suitable for low-power converter scenarios. It can effectively reduce the voltage stress of the main switching transistor, extend the service life of the device, and improve the overall reliability of the system. Its simple structure and superior performance make it widely applicable to a variety of power electronic devices.

[0051] The above description, in conjunction with specific / preferred embodiments, provides a further detailed explanation of the present invention and should not be construed as limiting the specific implementation of the present invention 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 protection scope 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 feature, structure, material, or characteristic described in connection with that embodiment or example is 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. Furthermore, the described specific features, structures, materials, or characteristics can be combined in a suitable manner in any one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the scope of protection of the patent application.

Claims

1. A spike voltage absorption circuit, characterized in that: The device includes a peak voltage absorption module and a capacitive element, which are connected in parallel. The peak voltage absorption module is used to adjust the clamping voltage based on the voltage regulation principle. The peak voltage absorption module includes a Zener diode and a bipolar transistor. The capacitive element includes a first capacitor. The positive terminal of the Zener diode is electrically connected to the base of the bipolar transistor, and the negative terminal of the Zener diode is electrically connected to the collector of the bipolar transistor. One end of the first capacitor is electrically connected between the negative terminal of the Zener diode and the collector of the bipolar transistor, and the other end of the first capacitor is electrically connected to the emitter of the bipolar transistor.

2. The spike voltage absorption circuit as described in claim 1, characterized in that: It also includes a first resistor and a second resistor; one end of the first capacitor is connected between the first resistor and the second resistor, the first capacitor is electrically connected to the negative terminal of the Zener diode through the first resistor, and the first capacitor is electrically connected to the collector of the bipolar transistor through the second resistor.

3. A converter circuit, characterized in that: It includes a transformer, a transformer primary circuit, a transformer secondary circuit, and a peak voltage absorption circuit as described in any one of claims 1-2, wherein the peak voltage absorption circuit, the transformer primary circuit, and one side of the transformer are electrically connected in sequence, and the other side of the transformer is electrically connected to the transformer secondary circuit.

4. A converter circuit as described in claim 3, characterized in that: The primary circuit of the transformer includes a first rectifier diode, a first switching transistor, and a second capacitor. The anode of the first rectifier diode is electrically connected to the drain of the first switching transistor and one side of the transformer. The cathode of the first rectifier diode is electrically connected to one end of the first capacitor, the cathode of the Zener diode, and the collector of the bipolar transistor. The source of the first switching transistor is grounded. One end of the second capacitor is electrically connected to the current input terminal, the other end of the first capacitor, and the emitter of the bipolar transistor. The other end of the second capacitor is grounded.

5. A converter circuit as described in claim 3, characterized in that: The primary circuit of the transformer includes a first inductor, a second inductor, a first rectifier diode, a second rectifier diode, a second capacitor, a first switching transistor, and a second switching transistor. One end of the first inductor and the second inductor are both electrically connected to the current input terminal. The other end of the first inductor is both electrically connected to the anode of the first rectifier diode, one side of the transformer, and the drain of the first switching transistor. The other end of the second inductor is both electrically connected to the anode of the second rectifier diode, one side of the transformer, and the drain of the second switching transistor.

6. A converter circuit as described in claim 4, characterized in that: The secondary circuit of the transformer includes a third rectifier diode and a third capacitor. The positive terminal of the third rectifier diode is electrically connected to the other side of the transformer, the negative terminal of the third rectifier diode is electrically connected to one end of the third capacitor, and the other end of the third capacitor is electrically connected to the other side of the transformer, the zero potential terminal.

7. A converter circuit as described in claim 5, characterized in that: The transformer secondary circuit includes a third rectifier diode, a fourth rectifier diode, a fifth rectifier diode, a sixth rectifier diode, and a third capacitor. The positive terminals of the third rectifier diodes are all electrically connected to the other side of the transformer and the negative terminal of the fourth rectifier diode. The negative terminals of the third rectifier diodes are all electrically connected to the negative terminal of the fifth rectifier diode, the third capacitor, and the current output terminal. The positive terminals of the fourth rectifier diodes are all electrically connected to the positive terminal of the sixth rectifier diode, the other end of the third capacitor, and the zero potential terminal. The positive terminals of the fifth rectifier diodes are all electrically connected to the other side of the transformer and the negative terminal of the sixth rectifier diode.

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