Capacitor charging device

Abstract

The invention relates to a capacitor charging device, which comprises a power supply, a first capacitor, a first charging branch and at least one second charging branch, and is characterized in that each second charging branch is connected with the first charging branch in parallel, and each second charging branch comprises an automatic on-off element; under the condition that the voltage at the two ends of the first capacitor is smaller than a first preset voltage, the automatic on-off element in the at least one second charging branch is in a conducting state, and the first charging branch and the at least one second charging branch charge the first capacitor at the same time; and when the voltage at the two ends of 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 a cut-off state, and the first charging branch charges the first capacitor until the voltage at the two ends of the first capacitor reaches the second preset voltage. By connecting at least one charging branch comprising an automatic on-off element in parallel, the charging current of the output capacitor can be increased, and the time for the two ends of the output capacitor to reach the set voltage is shortened.

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; 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 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; the second preset voltage is greater than the power supply voltage.

[0006] In an optional embodiment, when the automatic on-off element is a first diode, the anode of the first diode 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, the cathode of the first diode 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 the difference between the power supply voltage and the conduction voltage drop of the first diode.

[0007] In an optional embodiment, when 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, 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.

[0008] In an optional embodiment, 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.

[0009] In an optional embodiment, when 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, and 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.

[0010] In an optional embodiment, 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.

[0011] In an optional embodiment, the capacitor charging device also includes a switch tube control module, which is connected to the gate of the switch tube and 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.

[0012] 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.

[0013] In an optional embodiment, the boost module also 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.

[0014] In an optional embodiment, the capacitor charging device further includes a voltage detection module, wherein the voltage detection module is connected to the first capacitor and is used to detect the voltage across the first capacitor.

[0015] Implementing the embodiments of the present invention has the following beneficial effects: 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 a 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 a 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 across the first capacitor increases, the automatic on-off element in at least one second charging branch becomes cut-off, and at least one second charging branch is equivalent to being disconnected. The first capacitor relies on the first charging branch to charge 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 first capacitor to reach the set voltage can be shortened, and the charging efficiency of the first capacitor can be improved, thereby shortening the starting time of the capacitor charging device. After the capacitor charging device is started, 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 due to large capacitance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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 described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of the structure of a capacitor charging device provided by an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a capacitor charging device in which an automatic switching element is a diode provided in an embodiment of the present invention; Figure 3 A schematic diagram of the structure of a capacitor charging device with an automatic on-off element in an off state provided by an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a capacitor charging device provided by an embodiment of the present invention; Figure 5 A schematic diagram of the structure of a capacitor charging device including a plurality of second charging branches provided in an embodiment of the present invention; Figure 6 A schematic diagram of the structure of a capacitor charging device in which the automatic switching element is a field effect tube provided in an embodiment of the present invention; Figure 7 A schematic diagram of the structure of a field effect transistor control module provided by an embodiment of the present invention; Figure 8 A schematic structural diagram of a capacitor charging device including a plurality of second charging branches provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, 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 "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices. The following combination Figure 1 , Figure 2 as well as Figure 3 , a capacitor charging device provided in an embodiment of this specification is specifically described.

[0020] like Figure 1 As 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 be based on the first capacitor C out The voltage change at both ends realizes the on-off state switching; 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, and the second end of each second charging branch is respectively connected to the second end of the first charging branch and the first capacitor C out The negative electrode of the power supply is connected to the first end of the first capacitor C out The second end of the first capacitor C out When the voltage at 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 on state, and the first charging branch and the at least one second charging branch are both the first capacitor C out Charging; the first preset voltage is less than or equal to the power supply voltage; at the first capacitor C out When the voltage at both ends 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 off state, and the first charging branch is the first capacitor C out Charge until the first capacitor C out The voltage at both ends reaches a second preset voltage; the second preset voltage is greater than the power supply voltage.

[0021] In the embodiment of the present specification, the boost module further includes a switch tube S1, and the switch tube S1 can be a triode or a MOS tube. Figure 2 Take the switch tube S1 as a MOS tube as an example. Figure 2 As shown, the drain D (Drain) of the switch tube S1 is connected to the middle node of the first charging branch, and the source S (source) of the switch tube S1 is connected to the negative electrode of the power supply and the second end of the first capacitor respectively. The switch tube S1 controls the energy storage and release process of the first charging branch so that the first charging branch charges the first capacitor C out charged, so that the first capacitor C out The voltage at both ends increases, achieving the boost function.

[0022] In the embodiment of the present specification, the capacitor charging device further includes a switch tube control module, the switch tube control module is connected to the gate G (Gate) of the switch tube S1, 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 S1; the switch tube control signal can be a pulse width modulation (Pulse Width Modulation, PWM) signal, and the PWM signal can control the on-time ratio (i.e., duty cycle) of the switch tube S1, thereby controlling the output voltage (i.e., the first capacitor C out The switch control module controls the duty cycle of the switch S1 by outputting a switch control signal, thereby controlling the first capacitor C out The voltage across the two ends is such that the first capacitor C out The voltage across both ends reaches the set output voltage.

[0023] In the embodiment of the present specification, the first charging branch includes an inductor L and a second diode D1, the first end of the inductor L 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 L is connected to the anode of the second diode D1, and the cathode of the second diode D1 is respectively connected to the second end of each second charging branch and the first capacitor C out When the switch tube S1 is turned on, current passes through the inductor L, the magnetic field energy in the inductor L gradually increases, and the electrical energy is converted into magnetic energy and stored. When the switch tube S1 is turned off, the magnetic field energy in the inductor L begins to be released, and the first capacitor C out 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 the current.

[0024] In the embodiment of the present specification, when the automatic on-off element is a first diode, the anode of the first diode 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 cathode of the first diode in each second charging branch is respectively connected to the second end of the first charging branch and the first capacitor C out is connected to a first end of , and the first preset voltage is a difference between the power supply voltage and a conduction voltage drop of the first diode.

[0025] In the embodiments of this specification, Figure 2 As shown, the second charging branch can have one, the power supply is a DC power supply, V in is the power supply voltage, V c The first capacitor C out The voltage across the two ends, I1 is the charging current of the first charging branch, I2 is the charging current of the second charging branch, V on is the conduction voltage drop of the first diode D2. out The voltage across the two ends is V c <V in -V on At this time, the first diode D2 is forward-conducting. At the same time, regardless of whether the switch tube S1 is turned on or not, at the initial start-up of the capacitor charging device, I1 and I2 can both charge the first capacitor C out Charges the first capacitor C out The voltage across the terminals quickly rises to V c =V in -V on .

[0026] In the embodiments of this specification, Figure 3 As shown, when the first capacitor C out The voltage across the two ends is V c ≥V in -V on When the first diode D2 is reversely cut off, the second charging branch is 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 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 set output voltage, that is, 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 first diode in parallel. out The charging current shortens the first capacitor Cout 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.

[0027] For example, if the power supply voltage is 5V, the second preset voltage is 12V, and the conduction 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 first capacitor C out When the voltage at both ends is less than 4.3V, the first diode D2 in the at least one second charging branch is in a conducting state, and the first charging branch and the at least one second charging branch are both the first capacitor C out 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 a cut-off state, the at least one second charging branch is equivalent to an open circuit, and the first charging branch is the first capacitor C out Charge until the first capacitor C out The voltage across both ends reaches 12V.

[0028] In the embodiments of this specification, the first diode should be a diode with reduced forward conduction voltage, small reverse leakage current, and high reverse breakdown voltage to ensure as long an auxiliary charging time as possible and as little interference as possible after the capacitor charging device is started.

[0029] In the embodiments of this specification, Figure 4 As shown, the boost module also includes a second capacitor C in , the second capacitor C in The first end of the second charging branch 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 capacitor C in The second end is respectively connected to the negative electrode of the power supply and the first capacitor C out The second end of the second capacitor C in It is used to filter out ripple voltage and assist the power supply in providing current, thereby improving the stability of the circuit.

[0030] In the embodiment of the present specification, the capacitor charging device further includes a voltage detection module, and the voltage detection module is connected to the first capacitor C out connected to the first capacitor C out The voltage detection module is used to detect the voltage of the first capacitor C during the startup of the capacitor charging device. out The voltage across the terminals changes.

[0031] In the embodiment of this specification, the first capacitor Cout The two ends can be connected in parallel with the load, and the capacitor charging device charges the first capacitor C out Charges the first capacitor C out The voltage at both ends reaches a set output voltage, that is, the second preset voltage, so as to drive the load to work. The second preset voltage can be determined according to the driving voltage required for the normal operation of the load.

[0032] In the embodiments of this specification, Figure 5 As shown, there may be multiple second charging branches, each of which includes one of the first diodes. Figure 5 D2 and D3 in the figure both represent the first diode as the automatic switching element. The first capacitor C out The voltage across the two ends 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 conduction voltage drops of the first diodes D2 and D3 are both V on At the initial start-up of the capacitor charging device, the first capacitor C out The voltage across the two ends is V c <V in -V on At this time, the first diodes D2 and D3 are forward-conducting, and I1, I2 and I3 can all be connected to the first capacitor C out Charging; when the first capacitor C out The voltage across the two ends is V c ≥V in -V on When 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.

[0033] 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.

[0034] 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.

[0035] 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 .

[0036] 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 gs When the voltage 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, when the first capacitor C out When the voltage across the two ends is less than 5V, the second charging branch can assist the first charging branch to charge the first capacitor C out Charging the first capacitor C out When the voltage at both ends is greater than or equal to 5V, the field effect tube needs to be turned off to prevent the current from flowing back into the power supply; when the gate voltage V gs When the V gs -V th =5-0.5=4.5V <V in =5V, at this time the first preset voltage is V gs -Vth =4.5V, that is, the first capacitor C out When the voltage across the two ends is less than 4.5V, the second charging branch can assist the first charging branch to charge the first capacitor C out Charging the first capacitor C out When the voltage across the two ends is greater than or equal to 4.5V, the field effect tube needs to be turned off.

[0037] In another embodiment of this specification, Figure 6 As shown, the second charging branch may have one, V c The first capacitor C out The voltage at both ends is, I1 is the charging current of the first charging branch, and I2 is the charging current of the second charging branch. At the initial start of the capacitor charging device, the first capacitor C out The voltage across the two ends is V c is less than the first preset voltage, at which time the field effect tube S2 is in the on state. At the same time, regardless of whether the switch tube S1 is on or not, at the initial start-up of the capacitor charging device, I1 and I2 can both charge the first capacitor C out Charges the first capacitor C out The voltage across the terminals rises rapidly.

[0038] In another embodiment of this specification, Figure 3 As shown, when the first capacitor C out The voltage across the two ends is V c When the voltage is greater than or equal to the first preset voltage, the field effect transistor 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.

[0039] 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.

[0040] 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.

[0041] 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).

[0042] In another embodiment of the present specification, there may be multiple second charging branches, each of which includes one field effect transistor, and each field effect transistor is connected to a field effect transistor control module. out The voltage across the two ends is V c At the initial start-up of the capacitor charging device, the first capacitor C out The voltage across the two ends is V c is less than the first preset voltage, at this time, the field effect transistors in the plurality of second charging branches are all in a conducting state, and the first charging branch and the plurality of second charging branches can both be used to charge the first capacitor C out Charging; when the first capacitor C out The voltage across the two ends is V c When the voltage is greater than or equal to the first preset voltage, the field effect transistors in the plurality of second charging branches are all in the cut-off state, and the plurality of second charging branches are equivalent to being disconnected. At this time, the first charging branch completely charges the first capacitor C out Charge until the first capacitor C outThe voltage at both ends reaches the second preset voltage. It should be noted that the introduction of the field effect tube 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. In addition, when there are multiple second charging branches, the power-on sequence needs to be controlled, and the field effect tube control module needs to be powered on first, and then the capacitor charging device is controlled to power on and start.

[0043] 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 a first number, the automatic on-off elements in the second number of second charging branches are first diodes, and 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.

[0044] In another embodiment of this specification, Figure 8 As shown, Figure 8 Taking the first number being 2, the second number being 1, and the third number being 1 as an example, the boost module includes two second charging branches, wherein 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 plurality of 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 are simultaneously the first capacitor C out Charging; (2) The first charging branch and the second charging branch including the field effect transistor are both the first capacitor C out Charging; (3) The first charging branch is the first capacitor C out Charging. Specifically, V in is the power supply voltage, V c The first capacitor C out The voltage across the two ends, 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, V gs is the gate voltage of the field effect transistor S2. out The voltage across the two ends is V c <Vin -V on At this time, the first diode D2 and the field effect transistor S2 are both in the on state, and I1, I2, and I3 can all be the first capacitor C out Charging; when the first capacitor C out The voltage across the two ends is V c ≥V in -V on And V c When the voltage 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 on state. At this time, I1 and I3 are the first capacitor C out Charging; when the first capacitor C out The voltage across the two ends is V c When the voltage is greater than or equal to the first preset voltage, the first diode D2 and the field effect transistor S2 are both in the cut-off state. At this time, I1 is completely used to supply the first capacitor C 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 first diode and 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.

[0045] It should be noted that in V 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 .

[0046] For example, if the power supply voltage is 5V, the second preset voltage is 12V, the conduction voltage drop of the first diode D2 is 0.7V, and the threshold voltage V th is 0.5V, the gate voltage V gs 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. The first capacitor C out The voltage across the two ends is less than V in -V on =5-0.7=4.3V, the first diode D2 and the field effect transistor S2 are both in the on 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 be used to charge the first capacitor C out Charging; in the first capacitor C out The voltage across the two ends is V c ≥V in -V on =4.3V and V c When the voltage is less than the first preset voltage 4.5V, the first diode D2 is in the cut-off state, and the field effect transistor S2 is in the on state. At this time, the first charging branch and the second charging branch including the field effect transistor S2 are used to charge the first capacitor C out Charging; in the first capacitor C out The voltage across the two ends is V c When the voltage is greater than or equal to the first preset voltage 4.5V, the first diode D2 and the field effect transistor S2 are both in the cut-off state, and the first charging branch completely charges the first capacitor C out Charge until the first capacitor C out The voltage across both ends reaches 12V.

[0047] It can be seen from the above-mentioned embodiments of the capacitor charging device provided by the present invention that 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 realize on-off state switching based on the voltage change across 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, and 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, 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 the first preset voltage, the automatic on-off element in the at least one second charging branch is in the 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 the 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. The technical solution provided in the embodiment of this specification is to connect 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 the at least one second charging branch is in the on state, the first charging branch and the at least one second charging branch charge the first capacitor at the same time, as the voltage across the first capacitor increases, the automatic on-off element in the at least one second charging branch becomes off, and the at least one second charging branch is equivalent to a circuit breaker, and the first capacitor relies on the first charging branch to charge until the set output voltage is reached. By connecting in parallel at least one second charging branch including an automatic on-off element, the charging current of the first capacitor can be increased, the time for both ends of the first capacitor to reach a set voltage can be shortened, and the charging efficiency of the first capacitor can be improved, thereby shortening the startup time of the capacitor charging device. After the capacitor charging device is started, 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 large capacitance.

[0048] It should be noted that the order of the above embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The above describes specific embodiments of this specification, and other embodiments are within the scope of the attached claims. In some cases, the actions or steps recorded in the claims can be performed in a different order from that in the embodiments and still achieve the desired results. The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0049] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of 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 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; the second preset voltage is greater than the power supply voltage.

2. The capacitor charging device according to claim 1, characterized in that: When the automatic on-off element is a first diode, the anode of the first diode 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 cathode of the first diode 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 the difference between the power supply voltage and the conduction voltage drop of the first diode.

3. The capacitor charging device according to claim 1, characterized in that: In the case where 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, 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 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 tube and the threshold voltage of the field effect tube.

4. The capacitor charging device according to claim 3, 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.

5. 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.

6. The capacitor charging device according to any one of claims 1 to 5, 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.

7. The capacitor charging device according to claim 6, 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.

8. The capacitor charging device according to any one of claims 1 to 5, 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.

9. The capacitor charging device according to any one of claims 1 to 5, 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.

10. The capacitor charging device according to any one of claims 1 to 5, 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.

Images