A capacitor charging device

Abstract

The present invention relates to a capacitor charging device, which includes a power source, a first capacitor, a first charging branch, and at least one second charging branch. Each second charging branch is connected in parallel with the first charging branch, and each second charging branch includes an automatic on-off element; when the voltage across the first capacitor is less than a first preset voltage, the automatic on-off element in at least one second charging branch is in a conducting state, and the first charging branch and at least one second charging branch charge the first capacitor simultaneously; when the voltage across the first capacitor is greater than or equal to the first preset voltage, the automatic on-off element in at least one second charging branch is in a cut-off state, and the first charging branch charges the first capacitor until the voltage across the first capacitor reaches a second preset voltage. By connecting at least one charging branch containing an automatic on-off element in parallel, the present invention can increase the charging current of the output capacitor and shorten the time for the voltage across the output capacitor to reach the set voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of boost conversion, and in particular to a capacitor charging device. Background Art

[0002] In circuit design, boost circuit, as an important DC-DC conversion circuit, can convert low-voltage DC signals into high-voltage DC signals to meet the voltage requirements of different loads.

[0003] The output ripple voltage of the boost circuit is negatively correlated with the size of the output capacitor. Increasing the capacitance value of the output capacitor can effectively reduce the peak-to-peak value of the output ripple voltage. In addition, some product designs also require the connection of a large-capacity electrolytic capacitor at the output end of the boost circuit. When the load changes, the electrolytic capacitor can respond quickly and replenish energy to maintain the stability of the output voltage. The above two methods require the use of an output capacitor with a larger capacitance value, which will extend the charging time of the output capacitor, resulting in an extension of the startup time of the boost circuit, which in turn affects the normal function of the product. Summary of the invention

[0004] In order to solve the above technical problems, the present invention discloses a capacitor charging device, which can increase the charging current of the output capacitor, shorten the time for both ends of the output capacitor to reach a set voltage, and improve the charging efficiency of the output capacitor by connecting at least one charging branch including an automatic on-off element in parallel.

[0005] In order to achieve the above object, the present invention provides a capacitor charging device, the capacitor charging device includes a boost module, the boost module includes a power supply, a first capacitor, a first charging branch and at least one second charging branch, each second charging branch is connected in parallel with the first charging branch, each second charging branch includes an automatic on-off element, and the automatic on-off element can realize on-off state switching based on the voltage change at both ends of the first capacitor;

[0006] The first end of each second charging branch is respectively connected to the first end of the first charging branch and the positive electrode of the power supply, the second end of each second charging branch is respectively connected to the second end of the first charging branch and the first end of the first capacitor, and the negative electrode of the power supply is connected to the second end of the first capacitor;

[0007] When the voltage across the first capacitor is less than a first preset voltage, the automatic on-off element in the at least one second charging branch is in an on state, and the first charging branch and the at least one second charging branch charge the first capacitor at the same time; the first preset voltage is less than or equal to the power supply voltage;

[0008] When the voltage across the first capacitor is greater than or equal to the first preset voltage, the automatic on-off element in at least one of the second charging branches is in the cut-off state, and the first charging branch charges the first capacitor until the voltage across the first capacitor reaches the second preset voltage; the second preset voltage is greater than the power supply voltage.

[0009] In an alternative embodiment, when the automatic on-off element is a first diode, the anodes of the first diodes in each of the second charging branches are respectively connected to the first end of the first charging branch and the positive electrode of the power supply, and the cathodes of the first diodes in each of the second charging branches are respectively connected to the second end of the first charging branch and the first end of the first capacitor. The first preset voltage is the difference between the power supply voltage and the forward voltage drop of the first diode.

[0010] In an alternative embodiment, when the automatic on-off element is a field effect transistor, the drains of the field effect transistors in each of the second charging branches are respectively connected to the first end of the first charging branch and the positive electrode of the power supply, and the sources of the field effect transistors in each of the second charging branches are respectively connected to the second end of the first charging branch and the first end of the first capacitor. The first preset voltage is determined based on the power supply voltage, the gate voltage of the field effect transistor, and the threshold voltage of the field effect transistor.

[0011] In an alternative embodiment, the capacitor charging device further includes at least one field effect transistor control module. The number of the field effect transistor control modules is the same as the number of the second charging branches. The gates of the field effect transistors in each of the second charging branches are respectively connected to a field effect transistor control module. The at least one field effect transistor control module is configured to turn off the field effect transistors in at least one of the second charging branches when the voltage across the first capacitor is greater than or equal to the first preset voltage.

[0012] In an alternative embodiment, when the boost module includes a plurality of second charging branches and the number of the plurality of second charging branches is a first number, the automatic on-off elements in a second number of the second charging branches are first diodes, and the automatic on-off elements in a third number of the second charging branches are field effect transistors. The first number is the sum of the second number and the third number. The first preset voltage is determined based on the power supply voltage, the forward voltage drop of the first diode, the gate voltage of the field effect transistor, and the threshold voltage of the field effect transistor.

[0013] In an optional embodiment, the boost module further includes a switching transistor, the drain of the switching transistor is connected to the intermediate node of the first charging branch, and the source of the switching transistor is respectively connected to the negative electrode of the power supply and the second terminal of the first capacitor.

[0014] In an optional embodiment, the capacitor charging device further includes a switching transistor control module, the switching transistor control module is connected to the gate of the switching transistor, the switching transistor control module is configured to output a switching transistor control signal, and the switching transistor control signal is used to control the on and off of the switching transistor.

[0015] In an optional embodiment, the first charging branch includes an inductor and a second diode, the first end of the inductor is respectively connected to the first end of each second charging branch and the positive electrode of the power supply, the second end of the inductor is connected to the anode of the second diode, and the cathode of the second diode is respectively connected to the second end of each second charging branch and the first end of the first capacitor.

[0016] In an optional embodiment, the boost module further includes a second capacitor, the first end of the second capacitor is respectively connected to the first end of each second charging branch, the first end of the first charging branch and the positive electrode of the power supply, and the second end of the second capacitor is respectively connected to the negative electrode of the power supply and the second end of the first capacitor.

[0017] In an optional embodiment, the capacitor charging device further includes a voltage detection module, the voltage detection module is connected to the first capacitor, and the voltage detection module is configured to detect the voltage across the first capacitor.

[0018] Implementing the embodiments of the present invention has the following beneficial effects:

[0019] The capacitor charging device disclosed in the present invention has at least one second charging branch including an automatic on-off element connected in parallel at both ends of the first charging branch. In the initial stage of starting the capacitor charging device, the automatic on-off element in at least one second charging branch is in the conducting state, and the first charging branch and at least one second charging branch charge the first capacitor simultaneously. As the voltage across the first capacitor increases, the automatic on-off element in at least one second charging branch becomes in the cut-off state, and at least one second charging branch is equivalent to an open circuit. The first capacitor is charged by relying on the first charging branch until the set output voltage is reached. By connecting at least one second charging branch including an automatic on-off element in parallel, the charging current of the first capacitor can be increased, the time for the voltage across the first capacitor to reach the set voltage can be shortened, the charging efficiency of the first capacitor can be improved, thereby shortening the starting time of the capacitor charging device, and after the capacitor charging device is started up, the parallel second charging branch will not affect the normal operation of the first charging branch, effectively solving the problem of long capacitor charging time caused by a large capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the capacitor charging device described in the present invention, the drawings required for the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 Structural schematic diagram of a capacitor charging device provided by an embodiment of the present invention;

[0022] Figure 2 Structural schematic diagram of a capacitor charging device with a diode as the automatic on-off element provided by an embodiment of the present invention;

[0023] Figure 3 Structural schematic diagram of a capacitor charging device with the automatic on-off element in the cut-off state provided by an embodiment of the present invention;

[0024] Figure 4 Structural schematic diagram of a capacitor charging device provided by an embodiment of the present invention;

[0025] Figure 5 Structural schematic diagram of a capacitor charging device including multiple second charging branches provided by an embodiment of the present invention;

[0026] Figure 6 Structural schematic diagram of a capacitor charging device with a field effect transistor as the automatic on-off element provided by an embodiment of the present invention;

[0027] Figure 7 Structural schematic diagram of a field effect transistor control module provided by an embodiment of the present invention;

[0028] Figure 8 This is a schematic structural diagram of a capacitor charging device provided by an embodiment of the present invention, which includes multiple second charging branches. Detailed implementation manners

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned accompanying drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or server including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0031] The following will be specifically described in conjunction with Figure 1 、 Figure 2 and Figure 3 a capacitor charging device provided by an embodiment of this specification.

[0032] As Figure 1 shown, the capacitor charging device includes a boost module, and the boost module includes a power supply, a first capacitor C out , a first charging branch, and at least one second charging branch. Each second charging branch is connected in parallel with the first charging branch. Each second charging branch includes an automatic on-off element, and the automatic on-off element can realize the on-off state switching based on the voltage change across the first capacitor C out ; the first end of each second charging branch is respectively connected to the first end of the first charging branch and the positive pole of the power supply, the second end of each second charging branch is respectively connected to the second end of the first charging branch and the first end of the first capacitor C out , and the negative pole of the power supply is connected to the second end of the first capacitor C out ; when the voltage across the first capacitor C outWhen the voltage across both ends is less than the first preset voltage, the automatic on-off element in the at least one second charging branch is in the conducting state, and the first charging branch and the at least one second charging branch charge the first capacitor C simultaneously. out The first preset voltage is less than or equal to the power supply voltage; when the voltage across both ends of the first capacitor C out is greater than or equal to the first preset voltage, the automatic on-off element in the at least one second charging branch is in the cut-off state, and the first charging branch charges the first capacitor C out until the voltage across both ends of the first capacitor C out reaches the second preset voltage; the second preset voltage is greater than the power supply voltage.

[0033] In the embodiment of this specification, the boost module further includes a switching tube S1, and the switching tube S1 can be a triode or a MOS tube. Figure 2 Taking the switching tube S1 as a MOS tube as an example, as Figure 2 shown, the drain D (Drain) of the switching tube S1 is connected to the middle node of the first charging branch, and the source S (source) of the switching tube S1 is respectively connected to the negative pole of the power supply and the second end of the first capacitor. The switching tube S1 controls the energy storage and energy release process of the first charging branch, so that the first charging branch charges the first capacitor C out so as to increase the voltage across both ends of the first capacitor C out and realize the boost function.

[0034] In the embodiment of this specification, the capacitor charging device further includes a switching tube control module, which is connected to the gate G (Gate) of the switching tube S1. The switching tube control module is used to output a switching tube control signal, and the switching tube control signal is used to control the on-off of the switching tube S1; the switching tube control signal can be a Pulse Width Modulation (PWM) signal, and the PWM signal can control the on-time and off-time ratio (i.e., the duty cycle) of the switching tube S1, so as to control the magnitude of the output voltage (i.e., the voltage across both ends of the first capacitor C out ). The switching tube control module controls the duty cycle of the switching tube S1 by outputting a switching tube control signal, and further controls the magnitude of the voltage across both ends of the first capacitor C out so that the voltage across both ends of the first capacitor C out reaches the set output voltage.

[0035] In the embodiment of this specification, the first charging branch includes an inductor L and a second diode D1. The first end of the inductor L is connected to the first end of each second charging branch and the positive pole of the power supply respectively. The second end of the inductor L is connected to the anode of the second diode D1. The cathode of the second diode D1 is connected to the second end of each second charging branch and the first end of the first capacitor C out respectively. When the switching transistor S1 is turned on, current passes through the inductor L, and the magnetic field energy in the inductor L gradually increases, and electrical energy is converted into magnetic energy and stored. When the switching transistor S1 is turned off, the magnetic field energy in the inductor L begins to be released to charge the first capacitor C out , thereby achieving the effect of boosting voltage. In addition, the inductor L is also used to smooth the current, which helps to reduce the ripple in the circuit and improve the stability of the output voltage; the second diode D1 provides a freewheeling path for the current of the inductor L to ensure the unidirectional flow of current.

[0036] In the embodiment of this specification, when the automatic on-off element is the first diode, the anodes of the first diodes in each second charging branch are connected to the first end of the first charging branch and the positive pole of the power supply respectively, and the cathodes of the first diodes in each second charging branch are connected to the second end of the first charging branch and the first end of the first capacitor C out respectively, and the first preset voltage is the difference between the power supply voltage and the forward voltage drop of the first diode.

[0037] In the embodiment of this specification, as Figure 2 shown, there may be one second charging branch, the power supply is a DC power supply, V in is the power supply voltage, V c is the voltage across the first capacitor C out , I1 is the charging current of the first charging branch, I2 is the charging current of the second charging branch, and V on is the forward voltage drop of the first diode D2. At the initial stage of starting the capacitor charging device, the voltage V out across the first capacitor C c < V in - V on , and at this time the first diode D2 is forward-conducted. At the same time, regardless of whether the switching transistor S1 is turned on or not, at the initial stage of starting the capacitor charging device, I1 and I2 can both charge the first capacitor C out , so that the voltage across the first capacitor C out rapidly rises to V c = V in - V on .

[0038] In the embodiments of this specification, as Figure 3 shown, when the voltage V across the first capacitor C out ≥V c -V in -V on , the first diode D2 is reverse cutoff, and the second charging branch is equivalent to an open circuit. At this time, the charging current I1 of the first charging branch completely charges the first capacitor C out . The first charging branch charges the first capacitor C out according to the duty cycle of the switching transistor S1 until the voltage across the first capacitor C out reaches the set output voltage, i.e., the second preset voltage. By paralleling the second charging branch including the first diode in the embodiments of this specification, the charging current of the first capacitor C out can be increased, the time for the voltage across the first capacitor C out to reach the set voltage can be shortened, the charging efficiency of the first capacitor C out can be improved, and thus the startup time of the capacitor charging device can be shortened.

[0039] For example, if the power supply voltage is 5V, the second preset voltage is 12V, and the forward voltage drop of the first diode D2 is 0.7V, then the first preset voltage is 5 - 0.7 = 4.3V. That is, when the voltage across the first capacitor C out is less than 4.3V, the first diode D2 in the at least one second charging branch is in the conducting state, and the first charging branch and the at least one second charging branch charge the first capacitor C out simultaneously; when the voltage across the first capacitor is greater than or equal to 4.3V, the first diode D2 in the at least one second charging branch is in the cutoff state, the at least one second charging branch is equivalent to an open circuit, and the first charging branch charges the first capacitor C out until the voltage across the first capacitor C out reaches 12V.

[0040] In the embodiments of this specification, the first diode should be selected as a diode with a low forward conduction voltage drop, a small reverse leakage current, and a high reverse breakdown voltage to ensure as long an auxiliary charging time as possible and as little interference as possible to the capacitor charging device after startup is completed.

[0041] In the embodiments of this specification, as Figure 4 shown, the boost module further includes a second capacitor C in , the second capacitor C inThe first end of which is respectively connected to the first end of each of the second charging branches, the first end of the first charging branch, and the positive pole of the power supply. The second capacitor C in The second end of which is respectively connected to the negative pole of the power supply and the second end of the first capacitor C out The second end of which is connected. The second capacitor C in is used to filter out the ripple voltage and assist the power supply in providing current to improve the stability of the circuit.

[0042] In the embodiment of this specification, the capacitor charging device further includes a voltage detection module. The voltage detection module is connected to the first capacitor C out That is, it is connected in parallel with the first capacitor C out The voltage detection module is used to detect the voltage change across the first capacitor C out during the startup process of the capacitor charging device.

[0043] In the embodiment of this specification, the two ends of the first capacitor C out can be connected in parallel with the load. The capacitor charging device charges the first capacitor C out so that the voltage across the first capacitor C out reaches the set output voltage, that is, the second preset voltage, thereby driving the load to work. The second preset voltage can be determined according to the driving voltage required for the normal operation of the load.

[0044] In the embodiment of this specification, as Figure 5 shown, there can be multiple second charging branches. Each of the second charging branches includes one of the first diodes. Figure 5 D2 and D3 in both represent the first diode as the automatic on-off element. The voltage across the first capacitor C out is V c , the power supply voltage is V in , the charging current of the first charging branch is I1, the charging currents of the two second charging branches are I2 and I3 respectively, and the forward voltage drops of the first diodes D2 and D3 are both V on . At the initial stage of the startup of the capacitor charging device, the voltage V out across the first capacitor C c < V in - V on . At this time, the first diodes D2 and D3 are forward-conducting, and I1, I2, and I3 can all charge the first capacitor C out ; when the voltage V out across the first capacitor C c ≥ V in - V onWhen the first diodes D2 and D3 are reversely cut off, the two second charging branches are equivalent to being disconnected. At this time, the first capacitor C is completely charged by the charging current I1 of the first charging branch. out Charge until the first capacitor C out The voltage at both ends reaches the second preset voltage. In the embodiment of this specification, by connecting multiple second charging branches including the first diode in parallel, the first capacitor C out The charging current further shortens the first capacitor C out It should be noted that the introduction of the first diode will cause certain interference to the capacitor charging device, so the number of the second charging branches needs to be set according to the actual situation.

[0045] The following combination Figure 3 , Figure 6 as well as Figure 7 , a capacitor charging device provided in another embodiment of this specification is specifically described.

[0046] In another embodiment of the present specification, when the automatic on-off element is a field effect tube, the drain of the field effect tube in each second charging branch is respectively connected to the first end of the first charging branch and the positive electrode of the power supply, and the source of the field effect tube in each second charging branch is respectively connected to the second end of the first charging branch and the first capacitor C out The first preset voltage is determined based on the power supply voltage, the gate voltage of the field effect transistor and the threshold voltage of the field effect transistor.

[0047] In another embodiment of the present specification, the power supply is a DC power supply, V in is the power supply voltage, the field effect transistor may be a MOS transistor, V th is the threshold voltage of the field effect tube, V gs is the gate voltage of the field effect transistor. gs -V th ≥V in In the case where the first preset voltage is the power supply voltage V in , in V gs -V th <V in In the case where the first preset voltage is V gs -V th .

[0048] For example, if the power supply voltage V in is 5V, the threshold voltage of the field effect tube V th is 0.5V. The gate voltage V gsWhen it is 12V, V gs -V th =12 - 0.5 = 11.5V > V in = 5V. At this time, the first preset voltage is the power supply voltage V in , that is, the first preset voltage is 5V. That is to say, when the voltage across the first capacitor C out is less than 5V, the second charging branch can assist the first charging branch to charge the first capacitor C out together. When the voltage across the first capacitor C out is greater than or equal to 5V, the field effect transistor needs to be turned off to avoid current backflow into the power supply; when the gate voltage V gs of the field effect transistor is 5V, V gs -V th = 5 - 0.5 = 4.5V < V in = 5V. At this time, the first preset voltage is V gs -V th = 4.5V. That is to say, when the voltage across the first capacitor C out is less than 4.5V, the second charging branch can assist the first charging branch to charge the first capacitor C out together. When the voltage across the first capacitor C out is greater than or equal to 4.5V, the field effect transistor needs to be turned off.

[0049] In another embodiment of this specification, as Figure 6 shown, the second charging branch can be one. V c is the voltage across the first capacitor C out . I1 is the charging current of the first charging branch, and I2 is the charging current of the second charging branch. At the initial stage of starting the capacitor charging device, the voltage V out across the first capacitor C c is less than the first preset voltage. At this time, the field effect transistor S2 is in the conducting state. At the same time, regardless of whether the switching transistor S1 is conducting or not, at the initial stage of starting the capacitor charging device, both I1 and I2 can charge the first capacitor C out , so that the voltage across the first capacitor C out rises rapidly.

[0050] In another embodiment of this specification, as Figure 3 shown, when the voltage V out across the first capacitor C cWhen the voltage is greater than or equal to the first preset voltage, the field effect tube S2 is in the cut-off state, and the second charging branch is equivalent to being disconnected. At this time, the charging current I1 of the first charging branch is completely used to charge the first capacitor C out The first charging branch charges the first capacitor C according to the duty cycle of the switch tube S1. out Charge until the first capacitor C out The voltage at both ends reaches the second preset voltage. In the embodiment of this specification, the first capacitor C can be increased by connecting the second charging branch including the field effect transistor in parallel. out The charging current shortens the first capacitor C out When the voltage at both ends reaches the set value, the first capacitor C out The charging efficiency is improved, thereby shortening the startup time of the capacitor charging device. In addition, compared with the first diode, the on-resistance of the field effect tube is very low. When the output voltage is low, the voltage drop of the field effect tube is much smaller than that of the first diode, which has less impact on the entire circuit and less power loss.

[0051] In another embodiment of the present specification, the capacitor charging device further includes at least one field effect tube control module, the number of the field effect tube control modules is the same as the number of the second charging branches, the gate of the field effect tube in each second charging branch is respectively connected to a field effect tube control module, and the at least one field effect tube control module is used to charge the first capacitor C out When the voltage at both ends is greater than or equal to the first preset voltage, the field effect transistor in the at least one second charging branch is turned off.

[0052] In another embodiment of this specification, Figure 6 As shown, Figure 6 The IC control in the above is the field effect tube control module, wherein CT (control) represents the control signal output by the field effect tube control module, and FB represents the feedback signal. The field effect tube control module is used to control the first capacitor C out When the voltage at both ends is greater than or equal to the first preset voltage, the field effect transistor S2 in the second charging branch is turned off, so as to achieve precise control of the conduction and shutdown of the field effect transistor S2.

[0053] In another embodiment of this specification, Figure 7 As shown, there are two ways to implement the field effect tube control module, one is to control it through the GPIO port of the MCU, and the other is to control it through an analog switch. Among them, NO means normally open (Normally Open), and NC means normally closed (Normally Closed).

[0054] In another embodiment of the present specification, there may be multiple second charging branches, each of the second charging branches includes one of the field effect transistors, and each field effect transistor is connected to a field effect transistor control module. The voltage across the first capacitor C out is V c . At the initial stage of starting the capacitor charging device, the voltage V out across the first capacitor C c is less than the first preset voltage. At this time, the field effect transistors in the multiple second charging branches are all in the conducting state, and both the first charging branch and the multiple second charging branches can charge the first capacitor C out . When the voltage V out across the first capacitor C c is greater than or equal to the first preset voltage, the field effect transistors in the multiple second charging branches are all in the cut-off state, and the multiple second charging branches are equivalent to an open circuit. At this time, the first capacitor C out is completely charged by the first charging branch until the voltage across the first capacitor C out reaches the second preset voltage. It should be noted that the introduction of the field effect transistor will cause certain interference to the capacitor charging device. Therefore, the number of the second charging branches needs to be set according to the actual situation. In addition, when there are multiple second charging branches, the power-on timing needs to be controlled. The field effect transistor control module needs to be powered on first, and then control the capacitor charging device to be powered on and started.

[0055] In another embodiment of the present specification, when the boost module includes multiple second charging branches and the number of the multiple second charging branches is the first number, the automatic on-off element in the second number of second charging branches is a first diode, and the automatic on-off element in the third number of second charging branches is a field effect transistor. The first number is the sum of the second number and the third number, and the first preset voltage is determined based on the power supply voltage, the forward voltage drop of the first diode, the gate voltage of the field effect transistor, and the threshold voltage of the field effect transistor.

[0056] In another embodiment of the present specification, as Figure 8 shown, Figure 8Taking the first quantity as 2, the second quantity as 1, and the third quantity as 1 as an example, that is, the boost module includes 2 second charging branches. Among them, the automatic on-off element in one second charging branch is the first diode D2, and the automatic on-off element in one second charging branch is the field effect transistor S2. That is, the multiple second charging branches can be a combination of a second charging branch including a first diode and a second charging branch including a field effect transistor. The startup process of the capacitor charging device can be divided into three stages: (1) The first charging branch, the second charging branch including the first diode, and the second charging branch including the field effect transistor charge the first capacitor C out simultaneously; (2) The first charging branch and the second charging branch including the field effect transistor charge the first capacitor C out simultaneously; (3) The first charging branch charges the first capacitor C out alone. Specifically, V in is the power supply voltage, V c is the voltage across the first capacitor C out , I1 is the charging current of the first charging branch, I2 is the charging current of the second charging branch including the first diode D2, I3 is the charging current of the second charging branch including the field effect transistor S2, V on is the conduction voltage drop of the first diode D2, V th is the threshold voltage of the field effect transistor S2, and V gs is the gate voltage of the field effect transistor S2. At the initial stage of starting up the capacitor charging device, the voltage V out across the first capacitor C c < V in - V on . At this time, both the first diode D2 and the field effect transistor S2 are in the conducting state, and I1, I2, and I3 can all charge the first capacitor C out ; when the voltage V out across the first capacitor C c ≥ V in - V on and V c is less than the first preset voltage, the first diode D2 is in the cut-off state, and the field effect transistor S2 is in the conducting state. At this time, I1 and I3 charge the first capacitor C out ; when the voltage V out across the first capacitor C c is greater than or equal to the first preset voltage, both the first diode D2 and the field effect transistor S2 are in the cut-off state. At this time, I1 alone charges the first capacitor C out until the first capacitor C outThe voltage at both ends reaches the second preset voltage. In the embodiments of this specification, by paralleling a second charging branch including a first diode and a second charging branch including a field effect transistor, the charging current of the first capacitor C can be increased out , and the time for both ends of the first capacitor C out to reach the set voltage can be shortened, improving the charging efficiency of the first capacitor C out , thereby shortening the startup time of the capacitor charging device.

[0057] It should be noted that when V gs - V th ≥V in , the first preset voltage is the power supply voltage V in . When V gs - V th < V in , the first preset voltage is V gs - V th .

[0058] For example, if the power supply voltage is 5V, the second preset voltage is 12V, the forward voltage drop of the first diode D2 is 0.7V, the threshold voltage V th of the field effect transistor S2 is 0.5V, and the gate voltage V gs of the field effect transistor S2 is 5V, then V gs - V th = 5 - 0.5 = 4.5V < V in = 5V. At this time, the first preset voltage is V gs - V th = 4.5V. When the voltage at both ends of the first capacitor C out is less than V in - V on = 5 - 0.7 = 4.3V, both the first diode D2 and the field effect transistor S2 are in the conducting state. At this time, the first charging branch, the second charging branch including the first diode D2, and the second charging branch including the field effect transistor S2 can all charge the first capacitor C out ; when the voltage V out at both ends of the first capacitor C c ≥V in - V on = 4.3V and V c is less than the first preset voltage of 4.5V, the first diode D2 is in the cut-off state, and the field effect transistor S2 is in the conducting state. At this time, the first charging branch and the second charging branch including the field effect transistor S2 charge the first capacitor C out ; when the first capacitor C outThe voltage V at both ends c When it is greater than or equal to the first preset voltage of 4.5V, both the first diode D2 and the field-effect transistor S2 are in the cut-off state. At this time, the first capacitor C is completely charged by the first charging branch out until the voltage at both ends of the first capacitor C out reaches 12V.

[0059] As can be seen from the embodiments of the capacitor charging device provided by the present invention above, the capacitor charging device described in the embodiments of the present invention includes a boost module. The boost module includes a power supply, a first capacitor, a first charging branch, and at least one second charging branch. Each second charging branch is connected in parallel with the first charging branch. Each second charging branch includes an automatic on-off element, and the automatic on-off element can switch the on-off state based on the voltage change at both ends of the first capacitor; the first end of each second charging branch is respectively connected to the first end of the first charging branch and the positive pole of the power supply, the second end of each second charging branch is respectively connected to the second end of the first charging branch and the first end of the first capacitor, and the negative pole of the power supply is connected to the second end of the first capacitor; when the voltage at both ends of the first capacitor is less than the first preset voltage, the automatic on-off element in at least one second charging branch is in the conducting state, and the first charging branch and the at least one second charging branch charge the first capacitor at the same time; the first preset voltage is less than or equal to the power supply voltage; when the voltage at both ends of the first capacitor is greater than or equal to the first preset voltage, the automatic on-off element in at least one second charging branch is in the cut-off state, and the first charging branch charges the first capacitor until the voltage at both ends of the first capacitor reaches the second preset voltage; the second preset voltage is greater than the power supply voltage. The technical solution provided in the embodiments of this specification connects at least one second charging branch including an automatic on-off element in parallel at both ends of the first charging branch. In the initial stage of starting the capacitor charging device, the automatic on-off element in at least one second charging branch is in the conducting state, and the first charging branch and at least one second charging branch charge the first capacitor at the same time. As the voltage at both ends of the first capacitor increases, the automatic on-off element in at least one second charging branch becomes in the cut-off state, and at least one second charging branch is equivalent to an open circuit. The first capacitor is charged by the first charging branch until the set output voltage is reached. By connecting at least one second charging branch including an automatic on-off element in parallel, the charging current of the first capacitor can be increased, the time for the voltage at both ends of the first capacitor to reach the set voltage can be shortened, the charging efficiency of the first capacitor can be improved, thereby shortening the start-up time of the capacitor charging device, and after the capacitor charging device is started up, the parallel second charging branch will not affect the normal operation of the first charging branch, effectively solving the problem of long capacitor charging time caused by a large capacitor.

[0060] It should be noted that: the above sequence of the embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. In addition, the specific embodiments of this specification have been described, and other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims may be executed in a different order from those in the embodiments and still achieve the desired results.

[0061] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the key point of each embodiment is to illustrate the differences from other embodiments.

[0062] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A capacitor charging device, characterized in that: The capacitor charging device includes a boost module, the boost module includes a power supply, a first capacitor, a first charging branch and at least one second charging branch, each second charging branch is connected in parallel with the first charging branch, each second charging branch includes an automatic on-off element, and the automatic on-off element can realize on-off state switching based on the voltage change at both ends of the first capacitor; The first end of each second charging branch is respectively connected to the first end of the first charging branch and the positive electrode of the power supply, the second end of each second charging branch is respectively connected to the second end of the first charging branch and the first end of the first capacitor, and the negative electrode of the power supply is connected to the second end of the first capacitor; When the voltage across the first capacitor is less than a first preset voltage, the automatic on-off element in the at least one second charging branch is in an on state, and the first charging branch and the at least one second charging branch charge the first capacitor at the same time; the first preset voltage is less than or equal to the power supply voltage; When the voltage across the first capacitor is greater than or equal to the first preset voltage, the automatic on-off element in the at least one second charging branch is in an off state, and the first charging branch charges the first capacitor until the voltage across the first capacitor reaches a second preset voltage; the second preset voltage is greater than the power supply voltage; In the case where the automatic on-off element is a first diode, an anode of the first diode in each second charging branch is respectively connected to a first end of the first charging branch and a positive electrode of the power supply, a cathode of the first diode in each second charging branch is respectively connected to a second end of the first charging branch and a first end of the first capacitor, and the first preset voltage is a difference between the power supply voltage and a conduction voltage drop of the first diode; In the case where the automatic on-off element is a field effect transistor, the drain of the field effect transistor in each second charging branch is respectively connected to the first end of the first charging branch and the positive electrode of the power supply, and the source of the field effect transistor in each second charging branch is respectively connected to the second end of the first charging branch and the first end of the first capacitor, and the first preset voltage is determined based on the power supply voltage, the gate voltage of the field effect transistor, and the threshold voltage of the field effect transistor; when the difference between the gate voltage and the threshold voltage is greater than or equal to the power supply voltage, the first preset voltage is the power supply voltage, and when the difference between the gate voltage and the threshold voltage is less than the power supply voltage, the first preset voltage is the difference between the gate voltage and the threshold voltage.

2. The capacitor charging device according to claim 1, characterized in that: The capacitor charging device also includes at least one field effect transistor control module, the number of the field effect transistor control modules is the same as the number of the second charging branches, the gate of the field effect transistor in each second charging branch is respectively connected to a field effect transistor control module, and the at least one field effect transistor control module is used to turn off the field effect transistor in the at least one second charging branch when the voltage across the first capacitor is greater than or equal to the first preset voltage.

3. The capacitor charging device according to claim 1, characterized in that: In the case where the boost module includes multiple second charging branches and the number of the multiple second charging branches is a first number, the automatic on-off elements in the second number of second charging branches are first diodes, the automatic on-off elements in the third number of second charging branches are field effect transistors, the first number is the sum of the second number and the third number, and the first preset voltage is determined based on the power supply voltage, the conduction voltage drop of the first diode, the gate voltage of the field effect transistor, and the threshold voltage of the field effect transistor.

4. The capacitor charging device according to any one of claims 1 to 3, characterized in that: The boost module further includes a switch tube, a drain of the switch tube is connected to the middle node of the first charging branch, and a source of the switch tube is respectively connected to the negative electrode of the power supply and the second end of the first capacitor.

5. The capacitor charging device according to claim 4, characterized in that: The capacitor charging device also includes a switch tube control module, which is connected to the gate of the switch tube. The switch tube control module is used to output a switch tube control signal, and the switch tube control signal is used to control the on and off of the switch tube.

6. The capacitor charging device according to any one of claims 1 to 3, characterized in that: The first charging branch includes an inductor and a second diode, the first end of the inductor is respectively connected to the first end of each second charging branch and the positive electrode of the power supply, the second end of the inductor is connected to the anode of the second diode, and the cathode of the second diode is respectively connected to the second end of each second charging branch and the first end of the first capacitor.

7. The capacitor charging device according to any one of claims 1 to 3, characterized in that: The boost module also includes a second capacitor, a first end of the second capacitor is respectively connected to the first end of each second charging branch, the first end of the first charging branch and the positive electrode of the power supply, and a second end of the second capacitor is respectively connected to the negative electrode of the power supply and the second end of the first capacitor.

8. The capacitor charging device according to any one of claims 1 to 3, characterized in that: The capacitor charging device further includes a voltage detection module, which is connected to the first capacitor and is used to detect the voltage across the first capacitor.

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