Secondary unlocking circuit

Abstract

The utility model discloses a secondary unlocking circuit. The secondary unlocking circuit comprises a main switch, a secondary switch, a load and at least one protective resistor, wherein the main switch, the secondary switch and the load are sequentially connected in series between a power supply positive electrode and a power supply negative electrode, a control signal is accessed to a control end of the secondary switch, and the protective resistor is connected in parallel with the main switch. In the secondary unlocking circuit, the protective resistor is connected in parallel with the main switch, and the protective resistor is connected between the positive electrode of the power supply and the secondary switch. When the main switch is switched off, the secondary switch is connected with the positive electrode of the power supply for charging under the current limitation of the protective resistor; after the main switch is closed, the voltage change of the secondary switch is small. The secondary switch is small in voltage difference before and after the main switch is closed, so that the transient current of the secondary switch on the load side is small, the load is prevented from being triggered by mistake instantly after the main switch is closed, the damage of the load caused by mistake triggering is avoided, and the cost is saved.

Description

Technical Field

[0001] This utility model relates to the field of pyrotechnic unlocking technology, and in particular to a two-stage unlocking circuit. Background Technology

[0002] The pyrotechnic unlocking circuits commonly used in existing satellites include a two-stage unlocking circuit: a main switch and a secondary switch.

[0003] When the pyrotechnic unlocking circuit is working, the main switch closes first, energizing the secondary unlocking circuit; then the control signal controls the secondary switch to close, energizing the bridge wire of the pyrotechnic and enabling the pyrotechnic to work.

[0004] At the moment the main switch is turned on, the contacts of the secondary unlocking circuit will vibrate at high frequency due to the characteristics of the relay itself, which may cause the pyrotechnic components of the secondary switch to malfunction due to abnormal energization. Utility Model Content

[0005] This invention provides a two-stage unlocking circuit to solve the problem of false triggering of loads in current unlocking circuits.

[0006] This utility model provides a two-stage unlocking circuit, including: a main switch, a secondary switch, a load, and at least one protective resistor;

[0007] The main switch, the secondary switch, and the load are connected in series between the positive and negative terminals of the power supply. The control terminal of the secondary switch is connected to a control signal, and the protection resistor is connected in parallel with the main switch.

[0008] Optionally, a first protective resistor and a second protective resistor are included, wherein the first protective resistor and the second protective resistor are connected in parallel.

[0009] Optionally, the resistance values ​​of the first and second protection resistors are 20KΩ.

[0010] Optionally, the resistance value R of the protective resistor can be in the range of: R > V. CC / I 额 Among them, V CC I is the voltage between the positive and negative terminals of the power supply, R is the resistance of the protective resistor, and I is the voltage between the positive and negative terminals of the power supply. 额 The operating current of the load is denoted as .

[0011] Optionally, the secondary switch is a field-effect transistor;

[0012] In this configuration, the gate of the field-effect transistor serves as the control terminal of the secondary switch; the source of the field-effect transistor is connected to the main switch; and the drain of the field-effect transistor is connected to the load.

[0013] Optionally, it may also include a first resistor, a second resistor, and a third resistor; a control signal is input to the first terminal of the first resistor;

[0014] The second end of the first resistor is connected to the first end of the second resistor and the first end of the third resistor;

[0015] The second end of the second resistor is connected to the gate of the field-effect transistor, and the second end of the third resistor is connected to the source of the field-effect transistor.

[0016] Optionally, it may also include: protective elements;

[0017] The protective element is connected in series between the main switch and the secondary switch;

[0018] The protective element includes a fuse or a resistor.

[0019] Optionally, the voltage between the positive and negative terminals of the power supply is 28V.

[0020] Optionally, the load is a pyrotechnic bridge wire.

[0021] Optionally, the main switch is a relay.

[0022] In the two-stage unlocking circuit provided in this embodiment, a protective resistor is connected in parallel with the main switch, and the protective resistor is connected between the positive terminal of the power supply and the secondary switch. When the main switch is not closed, the protective resistor, connected to the positive terminal of the power supply and the secondary switch, already has a certain voltage on the high-side of the secondary switch. The voltage change of the secondary switch is small before and after the main switch is closed. This small voltage difference in the secondary switch before and after the main switch is closed also results in a small transient current on the load side of the secondary switch, preventing the load from being falsely triggered momentarily after the main switch is closed, thus avoiding damage to the load caused by false triggering and saving costs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a circuit diagram of a two-level unlocking circuit provided in an embodiment of this utility model;

[0025] Figure 2 This is a circuit diagram of another two-level unlocking circuit provided in this embodiment of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] Figure 1 This is a circuit diagram of a two-stage unlocking circuit provided in an embodiment of this utility model, as shown below. Figure 1 As shown, the secondary unlocking circuit includes: a main switch SW1, a secondary switch SW2, a load RL1, and at least one protective resistor R1; wherein, the main switch SW1, the secondary switch SW2, and the load RL1 are connected in series between the positive and negative terminals of the power supply, the control terminal of the secondary switch SW2 is connected to a control signal, and the protective resistor R1 is connected in parallel with the main switch SW1.

[0029] Specifically, the secondary unlocking circuit includes a main switch SW1 and a secondary switch SW2. When the secondary unlocking circuit is working, the main switch SW1 is first closed, and the secondary unlocking circuit is powered on; then, the high and low sides of the secondary switch SW2 are controlled by a control signal to conduct, thereby controlling the load RL1 to be energized.

[0030] A protective resistor R1 is connected in series between the positive terminal VCC of the power supply and the secondary switch SW2. When the main switch SW1 is open, the secondary switch SW2 is charged through the protective resistor R1 with a second voltage. When the main switch SW1 is closed, the protective resistor R1 is short-circuited, and the voltage across the secondary switch SW2 is the first voltage, which is greater than the second voltage. In this embodiment of the invention, the voltage difference between the secondary switch SW2 before and after the main switch SW1 is closed is the difference between the first voltage and the second voltage. In related technologies, the secondary unlocking circuit does not have a protective resistor R1 connected in parallel with the main switch SW1. When the main switch SW1 is open, the voltage across the secondary switch SW2 is 0; when the main switch SW1 is closed, the voltage across the secondary switch SW2 is the first voltage. In related technologies, the voltage difference between the secondary switch SW2 before and after the main switch SW1 is closed is the value of the first voltage. Therefore, Figure 1 In the two-stage unlocking circuit provided in this embodiment of the present invention, the secondary switch SW2 has a small voltage difference before and after the main switch SW1. In related technologies, the voltage difference between the secondary switch and the main switch in the two-stage unlocking circuit is large, which can cause the secondary switch to mis-turn on, ultimately causing a large transient current to be unexpectedly applied to the load, resulting in the load being falsely triggered.

[0031] For example, when the secondary switch SW2 is a field-effect transistor (FET), the parasitic capacitance between the source and drain of the FET MOS1 prevents sudden voltage changes across them. When the main switch SW1 closes, a transient current is generated at the drain of the FET due to a voltage surge at its source. This transient current may cause the load to be falsely triggered. However, when the protective resistor R1 establishes a voltage at the source of the FET beforehand, the secondary switch SW2 has a smaller voltage difference before and after the main switch SW1. The transient current generated at the drain of the FET due to the parasitic capacitance between the source and drain is also smaller, preventing the load RL1 from being falsely triggered.

[0032] In the two-stage unlocking circuit of this embodiment, a protective resistor is connected in parallel with the main switch. When the main switch is not closed, the protective resistor is connected to the positive terminal of the power supply and the secondary switch, at which point the secondary switch has a certain voltage. Therefore, the voltage change of the secondary switch is small before and after the main switch is closed. The small voltage difference of the secondary switch before and after the main switch is closed also results in a small transient current on the load side of the secondary switch, avoiding false triggering of the load momentarily after the main switch is closed, thus preventing damage to the load caused by false triggering and saving costs.

[0033] Based on the above embodiments, Figure 2 This is a circuit diagram of another two-level unlocking circuit provided in this embodiment of the present invention, as shown below. Figure 2As shown, the secondary unlocking circuit also includes: a first protection resistor R1 and a second protection resistor R1, which are connected in parallel.

[0034] The resistance values ​​of the first protection resistor R1 and the second protection resistor R1 are 20KΩ.

[0035] Specifically, the protection resistors can be set as a first protection resistor R1 and a second protection resistor R2. When one of the protection resistors fails, the other protection resistor can perform the protection function of the secondary unlocking circuit.

[0036] The resistance value of the protection resistor is set according to the rated operating voltage or rated operating current of the load. The resistance value of the protection resistor is such that the transient current caused by the voltage difference of the secondary switch SW2 before and after the main switch SW1 is closed will not cause the load RL1 to work unexpectedly.

[0037] Based on the above embodiments, the resistance value R of the protection resistor is in the range of: R > V CC / I 额 Among them, V CC I is the voltage between the positive and negative terminals of the power supply, R is the resistance of the protective resistor, and I is the voltage between the positive and negative terminals of the power supply. 额 The operating current of the load is denoted as SW2. The secondary switch SW2 is a field-effect transistor MOS1; the gate of the field-effect transistor MOS1 serves as the control terminal of the secondary switch SW2; the source of the field-effect transistor MOS1 is connected to the main switch SW1; and the drain of the field-effect transistor MOS1 is connected to the load RL1.

[0038] Specifically, the secondary switch SW2 is a field-effect transistor (MOSFET) 1. The source of MOSFET 1 is connected to the main switch SW1, and the drain is connected to the load. When the main switch SW1 is closed, the source is momentarily impacted by the supply voltage. The parasitic capacitances of the source and drain prevent the voltage across the source and drain from changing abruptly. As a result, a momentary voltage surge occurs at the drain of MOSFET 1, which varies with the voltage at the source.

[0039] At least one protective resistor is connected in parallel with the main switch SW1. Before the main switch SW1 closes, a voltage is established at the source terminal of the field-effect transistor MOS1 in advance. When the relay closes, this reduces the instantaneous current generated at the drain of the field-effect transistor MOS1 through its parasitic capacitance. Specifically, at the instant the relay closes, the transient current I generated at the drain of the field-effect transistor MOS1... A For: I A =V CC / R; where V CC I is the voltage between the positive terminal VCC and the negative terminal GND of the power supply, and R is the resistance value of the protection resistor. The selection of the protection resistor value directly affects I. A The value of I.A The value should be less than the operating current I of the load RL. 额 To prevent the load RL from being falsely triggered by the main switch SW1 at the moment of closing, the value of the protective resistor R is in the range of: R > V. CC / I 额 .

[0040] The secondary unlocking circuit also includes: a first resistor R21, a second resistor R22, and a third resistor R23; the first terminal of the first resistor R21 receives the control signal.

[0041] The second end of the first resistor R21 is connected to the first end of the second resistor R22 and the first end of the third resistor R23;

[0042] The second end of the second resistor R22 is connected to the gate of the field-effect switch MOS1, and the second end of the third resistor R23 is connected to the source of the field-effect switch MOS1.

[0043] Specifically, the first resistor R21 and the second resistor R22 form a voltage divider circuit. The voltage of the control signal input to the first terminal of the first resistor R21 is divided by these two resistors and then applied to the gate of the field-effect switch MOS1. The voltage value of the control signal can be set by the resistance values ​​of the first resistor R21 and the second resistor R22. The first resistor R21 and the second resistor R22 act as a gate protection circuit for the field-effect switch MOS1, preventing damage to the field-effect switch MOS1 caused by excessive voltage applied to the gate. The first terminal of the third resistor R23 is connected to the series node of the first resistor R21 and the second resistor R22, and the second terminal of the third resistor R23 is connected to the source of the field-effect switch MOS1. The voltage divider network formed by the third resistor R23, the second resistor R22, and the first resistor R21 affects the voltage difference between the gate and the source, thereby affecting the drain current of the field-effect switch MOS1 in the on-state. Meanwhile, after the circuit has been running for a period of time, the shift in the operating point of the field-effect switch may cause a failure in the secondary unlocking circuit. The voltage divider network composed of the third resistor R23, the second resistor R22, and the first resistor R21 can compensate for the gate-source voltage of the field-effect switch by adjusting the resistance values ​​of the three resistors, thereby improving the robustness of the secondary unlocking circuit.

[0044] Based on the above embodiments, continue to refer to Figure 2 ,like Figure 2 As shown, the secondary unlocking circuit also includes: a field-effect switch driving circuit; the output terminal of the field-effect switch driving circuit is connected to the gate of the field-effect switch MOS1, and the field-effect switch driving circuit is used to provide a turn-on signal for the field-effect switch MOS1.

[0045] The output of the field-effect switch driving circuit is connected to the gate of the field-effect switch MOS1 through terminal I1.

[0046] In the two-stage unlocking circuit, when the secondary switch SW2 is a field-effect transistor (MOSFET) MOS, the on / off state of MOSFET MOS is controlled by a controller and other modules, thereby controlling whether the load RL1 in the two-stage unlocking circuit is powered on or off. MOSFETs have a fast switching speed, enabling rapid response to control signals, achieving high-frequency switching control, and improving the overall performance of the circuit. Setting up a MOSFET driver circuit to control the on / off state of MOSFET MOS1 allows for more complex circuit control logic, enhancing the circuit's flexibility and speed of response.

[0047] Based on the above embodiments, such as Figure 2 As shown, it also includes: protection element F1; protection element F1 is connected in series between the main switch SW1 and the secondary switch SW2; protection element F1 includes: a fuse or a resistor.

[0048] Specifically, a protective element F1 is connected in series between the main switch SW1 and the secondary switch SW2. When the protective element F1 is a fuse, it can quickly blow and cut off the power supply to the entire circuit when a short circuit or overload occurs in the secondary unlocking circuit, thus protecting other components in the circuit from damage. Simultaneously, the fuse is connected in series on the high side of the load RL1. When a short circuit or overload occurs on the positive side of the power supply, the protective element F1 can respond quickly to the high side and blow, cutting off the power supply to the entire circuit, thus protecting other components in the circuit from damage. Compared to placing a fuse on the low side of the load RL1, the protective element F1 in this embodiment responds more quickly and is less susceptible to potential interference from the low side. When the protective element F1 is a resistor, it limits the current of the entire secondary unlocking circuit, protecting the components from current within a safe range.

[0049] Based on the above embodiments, such as Figure 2 As shown, the voltage between the positive and negative terminals of the power supply is 28V. Load RL1 is a pyrotechnic bridge wire. The main switch SW1 is a relay.

[0050] Specifically, when the voltage between the positive and negative terminals of the power supply is 28V, if a protective resistor R1 is not included in the relevant technology, there will be mechanical jitter when the main switch SW1 closes its contacts at the moment of activation. When the relay of the main switch SW1 is not closed, the voltage across both the high and low sides of the secondary switch SW2 is 0V. When the relay closes, the high side of the secondary switch SW2 is momentarily impacted by a supply voltage of approximately 28V. When the secondary switch SW2 is a field-effect transistor, the parasitic capacitance between its source and drain prevents a sudden voltage change. Therefore, the low side of the secondary switch SW2 experiences a momentary 28V surge, which varies with the voltage across the high side. Under these conditions, the measured load terminal experiences a fluctuation with a maximum amplitude of 20V and a duration of 50µs.

[0051] refer to Figure 2 In the secondary unlocking circuit of this embodiment, a protective resistor R1 is provided to establish a voltage on the high side of the secondary switch SW2 before the main switch SW1 is closed. When the secondary high-side switch SW2 is a field-effect transistor and the resistance of the protective resistor R1 is 10Ω, at the instant the main switch SW1 is closed, due to the current limiting effect of the protective resistor R1, only a current of 28V / 10KΩ = 2.8mA can pass through. However, when the load RL1 is a pyrotechnic bridge wire, its operating current is above 5A. Therefore, the current surge generated on the load RL1 at the instant the main switch SW1 is closed will not cause the load RL1 to be falsely triggered.

[0052] It should be understood that the various forms of the process shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this utility model can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this utility model can be achieved, and this is not limited herein.

[0053] The specific embodiments described above do not constitute a limitation on the scope of protection of this utility model. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A two-stage unlocking circuit, characterized in that, include: Main switch, secondary switch, load and at least one protective resistor; The main switch, the secondary switch, and the load are connected in series between the positive and negative terminals of the power supply. The control terminal of the secondary switch is connected to a control signal, and the protection resistor is connected in parallel with the main switch.

2. The two-stage unlocking circuit according to claim 1, characterized in that, It includes a first protective resistor and a second protective resistor, which are connected in parallel.

3. The two-stage unlocking circuit according to claim 2, characterized in that, The resistance values ​​of the first and second protective resistors are 20KΩ.

4. The two-stage unlocking circuit according to claim 1, characterized in that, The resistance value R of the protective resistor is in the range of: R > V CC / I 额 ; Among them, V CC I is the voltage between the positive and negative terminals of the power supply, R is the resistance of the protective resistor, and I is the voltage between the positive and negative terminals of the power supply. 额 The operating current of the load is denoted as .

5. The two-stage unlocking circuit according to claim 1, characterized in that, The secondary switch is a field-effect transistor; In this configuration, the gate of the field-effect transistor serves as the control terminal of the secondary switch; the source of the field-effect transistor is connected to the main switch; and the drain of the field-effect transistor is connected to the load.

6. The two-stage unlocking circuit according to claim 5, characterized in that, It also includes a first resistor, a second resistor, and a third resistor; the first terminal of the first resistor receives a control signal; The second end of the first resistor is connected to the first end of the second resistor and the first end of the third resistor; The second end of the second resistor is connected to the gate of the field-effect transistor, and the second end of the third resistor is connected to the source of the field-effect transistor.

7. The two-stage unlocking circuit according to claim 1, characterized in that, Also includes: Protective components; The protective element is connected in series between the main switch and the secondary switch; The protective element includes a fuse or a resistor.

8. The two-stage unlocking circuit according to claim 1, characterized in that, The voltage between the positive and negative terminals of the power supply is 28V.

9. The two-stage unlocking circuit according to claim 1, characterized in that, The load is a pyrotechnic bridge wire.

10. The two-stage unlocking circuit according to claim 1, characterized in that, The main switch is a relay.

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