Supercapacitor charging circuit based on transistor amplification characteristics

Abstract

The present invention provides a supercapacitor charging circuit based on triode amplification characteristics, including triodes Q1-Q3 and resistors R1-R8; the resistors R1 and R2 are connected in parallel, one of which is connected to a power supply, and the other is connected to ground after being connected in series with capacitor C1, and the collectors of Q2 and Q1 and one end of R3 are connected at the same time; the base of Q2 is connected to one end of R5 and R7, the other end of R5 is connected to a power supply, and the other end of R7 is grounded; the emitter of Q2 is connected to the emitter of Q3 and one end of R8, the other end of R8 is grounded, the other end of R3 is connected to the base of Q1 and the collector of Q3, the emitter of Q1 is connected to one end of R4 and the positive electrode of supercapacitor E1, the other end of R4 is connected to the base of Q3 and one end of R6, the other end of R6 is grounded, and the negative electrode of E1 is grounded. The present invention uses three triodes to adjust the supercapacitor charging voltage, and after charging is completed, it is in a balanced state of charging and discharging to ensure charging safety.

Description

Technical Field

[0001] The present invention relates to the field of electronic information and electronic circuit design, and in particular to a safe and efficient supercapacitor charge and discharge control circuit based on triode amplification characteristics. Background Art

[0002] With the rapid development of IoT technology, people's demands for products are becoming more and more diversified. In real-world designs, many products require the use of backup power to maintain the device's clock signal or power outage reporting function. Especially IoT products with communication functions, which carry the important task of data interaction, need to store and report the currently collected data in a timely manner in the event of a sudden power outage, which requires the device to have the function of power outage reporting. Commonly used solutions are batteries and supercapacitors.

[0003] Considering the long life requirements of industrial products, supercapacitor solutions are gaining more and more attention. To extend the service life of supercapacitors, it is necessary to use them reliably and strictly control their charging voltage. Then how to optimize the design to achieve efficient, safe and stable control of the supercapacitor charging and discharging circuit has become the research focus of the industry. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of how to achieve efficient and stable charge and discharge control of supercapacitors, and to propose a supercapacitor charging circuit based on the transistor amplification characteristics. Three transistors are used to adjust the maximum charging voltage. After charging is completed, the circuit is in a charge and discharge equilibrium state to ensure charging safety.

[0005] The technical solution of the present invention is:

[0006] The present invention provides a supercapacitor charging circuit based on transistor amplification characteristics, comprising transistors Q1-Q3 and resistors R1-R8;

[0007] The resistors R1 and R2 are connected in parallel, one of the parallel connection points is connected to the power supply VCC, the other parallel connection point is connected in series with the capacitor C1 and then grounded, and the parallel connection point is connected to the collectors of the transistors Q2 and Q1 and one end of the resistor R3; the base of the transistor Q2 is connected to the resistor R5 and one end of the resistor R7, the other end of the resistor R5 is connected to the power supply VCC, and the other end of the resistor R7 is grounded; the emitter of the transistor Q2 is connected to the emitter of the transistor Q3 and one end of the resistor R8, the other end of the resistor R8 is grounded, the other end of the resistor R3 is connected to the base of the transistor Q1 and the collector of the transistor Q3, the emitter of the transistor Q1 is connected to one end of the resistor R4 and the positive electrode of the super capacitor E1, the other end of the resistor R4 is connected to the base of the transistor Q3 and one end of the resistor R6, the other end of the resistor R6 is grounded, and the negative electrode of the super capacitor E1 is grounded.

[0008] Furthermore, the charging control circuit adopts the following control steps:

[0009] When powered on, the power supply VCC is turned on through the collector-emitter of transistor Q1 via R1 and R2 to charge supercapacitor E1. At the same time, at the emitter of transistor Q1, the current will be shunted to the ground through R4 and R6. At this time, the charging current of supercapacitor E1 is much greater than the discharging current.

[0010] At the same time, the collector voltage of transistor Q2 is greater than the base voltage and the emitter voltage, and transistor Q2 is in an amplification state; the emitter voltage of transistor Q2, that is, the emitter voltage of transistor Q3 plus the conduction voltage, is higher than the base voltage. At this time, most of the current is used to charge the supercapacitor;

[0011] When the charging voltage of supercapacitor E1 reaches the maximum charging voltage, transistor Q3 is turned on, the current flowing through the collector-emitter of transistor Q3 increases, the voltage drop between the collector and emitter of transistor Q1 decreases, and the current flowing through the collector-emitter of transistor Q1 decreases. At this time, the charging current of supercapacitor E1 and the discharge current of the supercapacitor through resistors R4 and R6 tend to be balanced and reach a stable state.

[0012] Furthermore, the amplification factors β of the three triodes are obtained by the following steps:

[0013] Get the power supply voltage VCC and the supercapacitor charging current range I charge ;

[0014] According to the power supply voltage VCC and the supercapacitor charging current range I charge , use the following formula to calculate the base current I of transistor Q1 bQ1 ;

[0015]

[0016] According to the base current I bQ1 and the transistor base-emitter conduction voltage V BE , use the following formula to calculate the base current I of transistor Q2 bQ2 and the transistor gain β, where V BE ≈0.7V;

[0017]

[0018] Furthermore, when the charging current range I charge The range is 20mA-40mA, V CC is 3.9V, transistor V BE When ≈0.7V, the amplification factor β of the transistor is 107-395.

[0019] Furthermore, the models of the three transistors are L2SC1623.

[0020] Beneficial effects of the present invention:

[0021] The present invention adopts three transistors to adjust the highest charging voltage. After charging is completed, the circuit is in a charging and discharging equilibrium state to ensure charging safety. The three transistors are all in an amplification state and a non-saturation switching function. Therefore, the gain parameter of the transistor has an impact on the final design of the circuit and is selected according to the actual design.

[0022] The method of the present invention realizes high-precision control and automatic balancing of the charging voltage; the circuit has a simple structure and low cost, is suitable for various supercapacitor charging scenarios, can effectively extend the service life of the supercapacitor, and improve charging efficiency and safety.

[0023] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0025] Figure 1 A supercapacitor charging circuit diagram based on triode amplification characteristics according to an embodiment of the present invention is shown.

[0026] Figure 2 A simulation diagram of a supercapacitor charging circuit according to an embodiment of the present invention is shown.

[0027] Figure 3 A circuit state simulation diagram is shown when a supercapacitor is just beginning to be charged according to an embodiment of the present invention.

[0028] Figure 4 A circuit state simulation diagram after a supercapacitor is fully charged according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0030] Figure 1 A supercapacitor charging circuit diagram based on triode amplification characteristics according to an embodiment of the present invention is shown.

[0031] like Figure 1 As shown, the present invention provides a supercapacitor charging circuit based on transistor amplification characteristics, including transistors Q1-Q3 and resistors R1-R8;

[0032] The resistors R1 and R2 are connected in parallel, one of the parallel connection points is connected to the power supply VCC, the other parallel connection point is connected in series with the capacitor C1 and then grounded, and the parallel connection point is connected to the collectors of the transistors Q2 and Q1 and one end of the resistor R3; the base of the transistor Q2 is connected to the resistor R5 and one end of the resistor R7, the other end of the resistor R5 is connected to the power supply VCC, and the other end of the resistor R7 is grounded; the emitter of the transistor Q2 is connected to the emitter of the transistor Q3 and one end of the resistor R8, the other end of the resistor R8 is grounded, the other end of the resistor R3 is connected to the base of the transistor Q1 and the collector of the transistor Q3, the emitter of the transistor Q1 is connected to one end of the resistor R4 and the positive electrode of the super capacitor E1, the other end of the resistor R4 is connected to the base of the transistor Q3 and one end of the resistor R6, the other end of the resistor R6 is grounded, and the negative electrode of the super capacitor E1 is grounded.

[0033] The charging control circuit adopts the following control steps:

[0034] When powered on, the power supply VCC is turned on through the collector-emitter of transistor Q1 via R1 and R2 to charge supercapacitor E1. At the same time, at the emitter of transistor Q1, the current will be shunted to the ground through R4 and R6. At this time, the charging current of supercapacitor E1 is much greater than the discharging current.

[0035] At the same time, the collector voltage of transistor Q2 is greater than the base voltage and the emitter voltage, and transistor Q2 is in an amplification state; the emitter voltage of transistor Q2, that is, the emitter voltage of transistor Q3 plus the conduction voltage, is higher than the base voltage. At this time, most of the current is used to charge the supercapacitor;

[0036] When the charging voltage of supercapacitor E1 reaches the maximum charging voltage, transistor Q3 is turned on, the current flowing through the collector-emitter of transistor Q3 increases, the voltage drop between the collector and emitter of transistor Q1 decreases, and the current flowing through the collector-emitter of transistor Q1 decreases. At this time, the charging current of supercapacitor E1 and the discharge current of the supercapacitor through resistors R4 and R6 tend to be balanced and reach a stable state.

[0037] In one example, the amplification factors β of the three triodes are obtained by the following steps:

[0038] Get the power supply voltage VCC and the supercapacitor charging current range I charge 20mA-40mA;

[0039] According to the power supply voltage VCC and the supercapacitor charging current range I charge, use the following formula to calculate the base current I of transistor Q1 bQ1 ;

[0040]

[0041] According to the base current I bQ1 and the transistor base-emitter conduction voltage V BE , use the following formula to calculate the base current I of transistor Q2 bQ2 and the transistor gain β, where V BE ≈0.7V;

[0042]

[0043] V CC is 3.9V, transistor V BE When ≈0.7V, the amplification factor β of the transistor is 107-395.

[0044] Based on the amplification factor β of 107-395, the model of the three transistors is L2SC1623.

[0045] according to Figure 1 Circuit design, this paper uses NI's Multisim software to simulate it, the simulation circuit is shown in Figure 2 The supercapacitor is simulated using an adjustable resistor R8. When the supercapacitor is empty and just starts to charge, both ends are close to a short-circuit state, and the impedance increases after it is fully charged.

[0046] Add voltage and current probes to observe the changes in voltage and current at each point in the circuit when charging begins and after it is fully charged; Figure 3 , after fully charged, see Figure 4 .

[0047] from Figure 3 From the above, we can see that the voltage across R8 is about 199mV, which simulates the state when the supercapacitor is fed.

[0048] At this time, Q1 and Q2 are both in the amplification state (collector forward biased, emitter forward biased), Q3 is in the cut-off state (collector reverse biased, emitter reverse biased), and the maximum charging current of the supercapacitor is about 20.6mA.

[0049] from Figure 4 From the above, the voltage across R8 is 2.19V, reaching the designed maximum charging voltage. At this time, transistors Q1, Q2, and Q3 are all in the amplification state, and the current flowing through R8 is approximately equal to 0A, and charging stops.

[0050] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A supercapacitor charging circuit based on triode amplification characteristics, characterized in that: Includes transistors Q1-Q3 and resistors R1-R8; The resistors R1 and R2 are connected in parallel, one of the parallel connection points is connected to the power supply VCC, the other parallel connection point is connected in series with the capacitor C1 and then grounded, and the parallel connection point is connected to the collectors of the transistors Q2 and Q1 and one end of the resistor R3; the base of the transistor Q2 is connected to the resistor R5 and one end of the resistor R7, the other end of the resistor R5 is connected to the power supply VCC, and the other end of the resistor R7 is grounded; the emitter of the transistor Q2 is connected to the emitter of the transistor Q3 and one end of the resistor R8, the other end of the resistor R8 is grounded, the other end of the resistor R3 is connected to the base of the transistor Q1 and the collector of the transistor Q3, the emitter of the transistor Q1 is connected to one end of the resistor R4 and the positive electrode of the super capacitor E1, the other end of the resistor R4 is connected to the base of the transistor Q3 and one end of the resistor R6, the other end of the resistor R6 is grounded, and the negative electrode of the super capacitor E1 is grounded.

2. The supercapacitor charging circuit based on triode amplification characteristics according to claim 1, characterized in that: The charging control circuit adopts the following control steps: When powered on, the power supply VCC is turned on through the collector-emitter of transistor Q1 via R1 and R2 to charge supercapacitor E1. At the same time, at the emitter of transistor Q1, the current will be shunted to the ground through R4 and R6. At this time, the charging current of supercapacitor E1 is much greater than the discharging current. At the same time, the collector voltage of transistor Q2 is greater than the base voltage and the emitter voltage, and transistor Q2 is in an amplification state; the emitter voltage of transistor Q2, that is, the emitter voltage of transistor Q3 plus the conduction voltage, is higher than the base voltage. At this time, most of the current is used to charge the supercapacitor; When the charging voltage of supercapacitor E1 reaches the maximum charging voltage, transistor Q3 is turned on, the current flowing through the collector-emitter of transistor Q3 increases, the voltage drop between the collector and emitter of transistor Q1 decreases, and the current flowing through the collector-emitter of transistor Q1 decreases. At this time, the charging current of supercapacitor E1 and the discharge current of the supercapacitor through resistors R4 and R6 tend to be balanced and reach a stable state.

3. The supercapacitor charging circuit based on triode amplification characteristics according to claim 1, characterized in that: The amplification factor β of the three triodes is obtained using the following steps; Get the power supply voltage VCC and the supercapacitor charging current range I charge ; According to the power supply voltage VCC and the supercapacitor charging current range I charge , use the following formula to calculate the base current I of transistor Q1 bQ1 ; According to the base current I bQ1 and the transistor base-emitter conduction voltage V BE , use the following formula to calculate the base current I of transistor Q2 bQ2 and the transistor gain β, where V BE ≈0.7V; 4. The supercapacitor charging circuit based on triode amplification characteristics according to claim 1, characterized in that: When the charging current range is I charge The range is 20mA-40mA, V CC is 3.9V, transistor V BE When ≈0.7V, the amplification factor β of the transistor is 107-395.

5. The supercapacitor charging circuit based on triode amplification characteristics according to claim 1, characterized in that: The models of the three transistors are L2SC1623.

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