CN103001297B - Series capacitor bank resonant type voltage balance charging method and system - Google Patents

Abstract

The invention discloses a series capacitor bank resonant type voltage balance charging method and a system. The method includes that a direct current charging power supply is used to charge a series capacitor bank, a voltage balance unit which is in a parallel connection with each capacitor monomer in the series capacitor bank comprises voltage reducing buffering and electric energy releasing modules which share an inductor/capacitor (LC) series connection structure, and capacitors are respectively in a parallel connection between source electrodes and drain electrodes of a buffer switch G1 and a release switch G2 which are complemented and connected. The capacitor monomers with slowest increasing terminal voltage are connected with a negative electrode of the direct current charging power supply. The system comprises the series capacitor bank and the direct current charging power supply, two ends of each capacitor monomer are in the parallel connection with the voltage balance units, and each voltage balance unit comprises a voltage detecting unit, a pulse modulation unit, a complementary driving unit, the release switch, the buffer switch and an LC series energy storage unit. By means of the series capacitor bank resonant type voltage balance charging method and the system, the problem of unbalance terminal voltage of the capacitor monomers in the process of capacitor series charging can be prevented, the energy consumption is low, and the structural expandability is high.

Description

A resonant voltage equalization charging method and system for a series capacitor bank

technical field

The invention relates to a resonant voltage equalization charging method and system for series capacitor banks. the

Background technique

Super capacitor is a new type of energy storage element realized by the principle of electric double layer. The rated voltage of the monomer is low, so in the actual application process, it is necessary to connect multiple monomers in series to meet the on-site needs of capacity and working voltage level. However, due to the limitations of production materials and manufacturing processes, even if the nominal parameters are completely consistent, the actual equivalent series internal resistance, capacity, charge-discharge rate and other parameters generally have significant differences. During use, the terminal voltage of the individual will show a typical imbalance. This phenomenon not only reduces the energy storage efficiency, but also may lead to overcharging of the monomer, which seriously affects the service life and reliability of the supercapacitor. the

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art and provide a resonant series capacitor bank that keeps the charging voltage of each capacitor unit in the series capacitor bank balanced, can prolong the service life of the capacitor unit, and has a significant energy-saving effect. A type voltage equalization charging method and system thereof. the

The purpose of the present invention is achieved through the following technical solutions:

The method includes charging the series capacitor bank by using a DC charging power supply; each capacitor monomer in the series capacitor bank is connected in parallel with a voltage equalization unit; in the voltage equalization unit:

(1) Step-down snubber module with RLC series circuit: composed of snubber switch G1, inductor L and capacitor C in LC series energy storage unit, the RLC series circuit works in an underdamped state, where R is G1, L and The sum of the equivalent resistance of C;

(2) Electric energy release module with RLC series circuit: It is composed of release switch G2 and inductor L and capacitor C in LC series energy storage unit. The RLC series circuit works in an underdamped state, where R is G2, L and C The sum of equivalent resistance, the electrical characteristics of G2 are the same as G1, and the equivalent internal resistance is also equal;

(3) The buffer switch G1 and the release switch G2 work in a complementary conduction state, and the switching period and duty cycle are consistent with the resonant frequency of the RLC series circuit;

(4) Capacitors are connected in parallel between the source and drain of the snubber switch G1 and the release switch G2, combined with the resonance characteristics of the RLC series circuits where they are located, the snubber switch G1 and the release switch G2 work in a soft switching state to reduce switching energy loss ;

(5) When the terminal voltage of the capacitor monomer exceeds a given threshold, the voltage detection unit in the voltage equalization unit outputs a high level, and the pulse modulation unit in the voltage equalization unit outputs a square wave with a certain period and duty cycle. The buffer switch G1 and the release switch G2 are driven by the complementary drive unit to be turned on or off in a complementary manner; when the terminal voltage of the capacitor monomer is lower than a given threshold, the voltage detection unit outputs a low level, and the pulse modulation unit always outputs a low level signal , at this time the buffer switch G1 is in the off state, and the release switch G2 is in the on state.

Connect the capacitor monomer with the slowest terminal voltage growth to the negative pole of the DC charging power supply. The voltage detection unit of the voltage equalization unit connected in parallel with the capacitor monomers of this level always outputs low level signals, and the pulse modulation unit always outputs low level signals. At this time G1 is always off, and G2 is always on, which can further reduce the energy consumption of the entire voltage equalization charging system. the

The system includes a capacitor bank in series and a DC charging power supply; a voltage equalization unit connected in parallel at both ends of each capacitor monomer in the capacitor bank in series; the voltage equalizer unit includes a voltage detection unit, a pulse modulation unit, a complementary drive unit, and a buffer switch , release switch, LC series energy storage unit; the input end of the voltage detection unit is connected to both ends of the capacitor monomer, the output end of the voltage detection unit is connected to the pulse modulation unit, the pulse modulation unit is connected to the complementary drive unit, and the two complementary drive units The output terminals are respectively connected to the buffer switch and the release switch, and the LC series energy storage unit is connected to the release switch and the buffer switch to form an RLC step-down release circuit and an RLC electric energy storage circuit respectively. the

The voltage detection unit adopts BL8506 integrated chip; the complementary driving unit adopts TPS28225 integrated chip; both the buffer switch G1 and the release switch G2 adopt Mosfet switch tubes. the

According to the resonance period, current and voltage zero-crossing characteristics and electrical characteristics determined by the corresponding RLC series circuit, a capacitor is connected in parallel between the source and drain of each Mosfet switch to ensure that the Mosfet switch works in a soft switching state and reduce the Mosfet. The switching loss of the switch tube. the

Compared with the prior art, the present invention has the following advantages: it can maintain the charging voltage balance of each capacitor monomer in the series capacitor bank, can effectively prolong the service life of the capacitor monomer, has low energy loss, remarkable energy-saving effect, and can be structured Strong scalability. the

Description of drawings

Fig. 1 is an electrical principle block diagram of an embodiment of the system of the present invention;

Fig. 2 is the main circuit diagram of an embodiment of the voltage equalization unit of 1;

In the figure: 1-capacitor monomer, 2-voltage equalization unit. .

Detailed ways

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

The method includes using a DC charging power supply to charge the series capacitor bank; each capacitor unit 1 in the series capacitor bank is connected in parallel with a voltage equalization unit; in the voltage equalization unit:

(1) Step-down snubber module with RLC series circuit: composed of snubber switch G1, inductor L and capacitor C in LC series energy storage unit, the RLC series circuit works in an underdamped state, where R is G1, L and The sum of the equivalent resistance of C;

(2) Electric energy release module with RLC series circuit: It is composed of release switch G2 and inductor L and capacitor C in LC series energy storage unit. The RLC series circuit works in an underdamped state, where R is G2, L and C The sum of equivalent resistance, the electrical characteristics of G2 are the same as G1, and the equivalent internal resistance is also equal;

(3) The buffer switch G1 and the release switch G2 work in a complementary conduction state, and the switching period and duty cycle are consistent with the resonant frequency of the RLC series circuit;

(4) Capacitors are connected in parallel between the source and drain of the snubber switch G1 and the release switch G2, combined with the resonance characteristics of the RLC series circuits where they are located, the snubber switch G1 and the release switch G2 work in a soft switching state to reduce switching energy loss ;

(5) When the terminal voltage of capacitor monomer 1 exceeds a given threshold, the voltage detection unit in the voltage equalization unit outputs a high level, and the pulse modulation unit in the voltage equalization unit outputs a square wave with a certain period and duty cycle , the buffer switch G1 and the release switch G2 are driven through the complementary drive unit to be turned on or off; when the terminal voltage of the capacitor unit (1) is lower than a given threshold, the voltage detection unit outputs a low level, and the pulse modulation unit always outputs low level signal, at this time the buffer switch G1 is in the off state, and the release switch G2 is in the on state.

Connect the capacitor unit 1 with the slowest terminal voltage increase to the negative pole of the DC charging power supply, the voltage detection unit of the voltage equalization unit connected in parallel with the capacitor unit 1 of this stage always outputs a low level, and the pulse modulation unit always outputs a low level signal, At this time, G1 is always off, and G2 is always on, which can further reduce the energy consumption of the entire voltage equalization charging system. the

The system includes a series capacitor bank and a DC charging power supply; a voltage equalization unit 2 is connected in parallel with each capacitor monomer 1 in the series capacitor bank; the voltage equalization unit 2 includes a voltage detection unit, a pulse modulation unit, and a complementary drive unit , a buffer switch, a release switch, and an LC series energy storage unit; the input end of the voltage detection unit is connected to both ends of the capacitor monomer 1, the output end of the voltage detection unit is connected to the pulse modulation unit, and the pulse modulation unit is connected to the complementary drive unit, and the complementary drive The two output terminals of the unit are respectively connected to a buffer switch and a release switch, and the LC series energy storage unit is connected to the release switch and the buffer switch to form an RLC step-down release circuit and an RLC electric energy storage circuit respectively. the

The voltage detection unit adopts BL8506 integrated chip; the complementary driving unit adopts TPS28225 integrated chip; both the buffer switch G1 and the release switch G2 adopt Mosfet switch tubes. the

According to the resonance period, current and voltage zero-crossing characteristics and electrical characteristics determined by the corresponding RLC series circuit, a capacitor is connected in parallel between the source and drain of each Mosfet switch to ensure that the Mosfet switch works in a soft switching state and reduce the Mosfet. The switching loss of the switch tube. the

Example of the system:

Referring to accompanying drawing 1, described system mainly is made up of series capacitor bank, DC charging power supply and voltage equalization unit 2; Both ends of each capacitor monomer 1 in the series capacitor bank are parallel-connected voltage equalization unit 2; Said voltage equalization unit 2 Including the voltage detection unit of the BL8506 integrated chip, the complementary drive unit of the TPS28225 integrated chip, the buffer switch of the Mosfet switch G1, the release switch of the Mosfet switch G2, and the LC series energy storage module of the LC circuit; the input terminal of the voltage detection unit is connected to Both ends of the capacitor monomer 1, the output terminal of the voltage detection unit is sequentially connected to the pulse modulation unit of the 555 integrated chip and the complementary driving unit of the TPS28225 integrated chip, and the two output terminals of the complementary driving unit are respectively connected to G1 and G2, G1 and G2 Capacitors C1 and C2 are connected in parallel between the source and the drain; the LC series energy storage unit and G2 form an RLC release circuit that discharges the C of the LC series energy storage unit; the LC series energy storage unit and G1 form a pair of LC series energy storage units C charges the RLC snubber circuit.

How the system embodiment works:

In the process of DC charging power supply DC charging the series capacitor bank, the current flowing through each capacitor unit 1 is the same, due to the difference in the individual internal resistance of the capacitor unit 1, the distribution of each capacitor unit 1 The voltages are not the same. When the voltage detection module of the BL8506 integrated chip of the voltage equalization unit 2 of a certain level of capacitor monomer 1 detects that the terminal voltage exceeds the set threshold, the output terminal of the BL8506 integrated chip outputs a high level, driving the oscillation of the 555 integrated chip Module, 555 integrated chip outputs control signals with specific frequency and duty cycle, and the complementary driving of TPS28225 integrated chip generates switch driving signals and controls G1 and G2 complementary conduction. When G1 is turned on and G2 is turned off, the capacitor unit 1 charges the capacitor C in the LC series energy storage unit through G1 and L and makes the terminal voltage of the capacitor unit 1 of this stage drop; when G1 is turned off, G2 is turned on, and the LC series storage unit The capacitor C in the energy unit discharges to the next series capacitor monomer through L and G2, and the result of the discharge is to increase the potential of the B terminal of the capacitor monomer 1 of the current stage, that is, to increase the potential of the A terminal of the lower capacitor monomer 1. The voltage equalization unit 2 makes full use of the resonance characteristics of the RLC circuit, and the switching tube is turned on or off only when the resonance current or voltage crosses zero. At the same time, the capacitors C1 and C2 connected in parallel to the Mosfet switch tubes G1 and G2 can effectively ensure zero-voltage cut-off, and the small inductance L in series can effectively ensure the zero-current conduction of the Mosfet switch tube. The above measures realize the soft switching function and can effectively reduce the Mosfet. The switching loss of the switching tube improves the system efficiency of the bypass shunt step-down.

In addition, the voltage equalization strategy is essentially an overvoltage protection strategy, that is, during the charging process of the series capacitor bank, only when the charging process is about to end or the actual parameter deviation of the series capacitor unit 1 causes the terminal When the voltage exceeds a given threshold, the corresponding voltage equalization unit 2 will work. At the same time, combined with soft switching technology, a low-energy overvoltage and step-down protection strategy for series capacitor banks can be realized. the

The present invention not only realizes the charging voltage balance of series capacitors through two associated under-damped RLC series circuits, but also cooperates with the drive signal sequence to make the switching tube work in a soft switching state, effectively reducing switching loss and having good structural scalability. . the

Claims (5)

1. A resonant voltage equalization charging method for a series capacitor bank, said method comprising charging the series capacitor bank with a DC charging power supply; each capacitor monomer (1) in the series capacitor bank is connected in parallel with a voltage equalization unit; it is characterized in that: In the voltage equalization unit: (1) Step-down snubber module with a first RLC series circuit: it is composed of a snubber switch G1 and an inductor L and a capacitor C in an LC series energy storage unit. The RLC series circuit works in an underdamped state, and the first resistor R is the sum of the equivalent resistances of G1, L and C; (2) The power release module with the second RLC series circuit: it is composed of the release switch G2 and the inductor L and capacitor C in the LC series energy storage unit. The RLC series circuit works in an underdamped state, and the second resistance R is G2 , the sum of the equivalent resistance of L and C, the electrical characteristics of G2 are the same as G1, and the equivalent internal resistance is also equal; (3) The buffer switch G1 and the release switch G2 work in a complementary conduction state, and the switching period and duty cycle are consistent with the resonant frequency of the RLC series circuit; (4) Capacitors are connected in parallel between the source and drain of the snubber switch G1 and the release switch G2, combined with the resonance characteristics of the RLC series circuits where they are located, the snubber switch G1 and the release switch G2 work in a soft switching state to reduce switching energy loss ; (5) When the terminal voltage of the capacitor monomer (1) exceeds a given threshold, the voltage detection unit in the voltage equalization unit outputs a high level, and the pulse modulation unit in the voltage equalization unit outputs a signal with a certain period and duty cycle Square wave, through the complementary driving unit to drive the buffer switch G1 and the release switch G2 to be turned on or off; when the terminal voltage of the capacitor monomer (1) is lower than a given threshold, the voltage detection unit outputs a low level, and the pulse modulation unit The low level signal is output all the time, at this moment, the buffer switch G1 is in the off state, and the release switch G2 is in the on state. 2. The method according to claim 1, characterized in that: the capacitor monomer (1) with the slowest terminal voltage growth is connected to the negative pole of the DC charging power supply, and the voltage detection of the voltage equalization unit connected in parallel with the capacitor monomers (1) The unit always outputs a low level signal, and the pulse modulation unit always outputs a low level signal. At this time, the buffer switch G1 is always turned off, and the release switch G2 is always turned on, which can further reduce the energy consumption of the entire voltage equalization charging system. 3. A series capacitor bank resonant voltage equalization charging system suitable for the method of claim 1 or 2, said system comprising a series capacitor bank and a DC charging power supply; each capacitor unit (1) in the series capacitor bank A voltage equalization unit (2) is connected in parallel at both ends; it is characterized in that: the voltage equalization unit (2) includes a voltage detection unit, a pulse modulation unit, a complementary drive unit, a buffer switch G1, a release switch G2, and an LC series energy storage unit; The input terminal of the voltage detection unit is connected to both ends of the capacitor unit (1), the output terminal of the voltage detection unit is connected to the pulse modulation unit, the pulse modulation unit is connected to the complementary drive unit, and the first output terminal of the complementary drive unit is connected to the buffer switch G1, The second output end is connected to the release switch G2, and the LC series energy storage unit is connected to the release switch G2 and the buffer switch G1 to form an electric energy release circuit with the second RLC series circuit and a step-down buffer circuit with the first RLC series circuit respectively. 4. The system according to claim 3, characterized in that: said voltage detection unit adopts BL8506 integrated chip; complementary drive unit adopts TPS28225 integrated chip; buffer switch G1 and release switch G2 both adopt Mosfet switch tube. 5. The system according to claim 4, characterized in that: according to the resonance period, current and voltage zero-crossing characteristics and electrical characteristics determined by the corresponding RLC series circuit, the source and drain of each Mosfet switch tube are connected in parallel A capacitor ensures that the Mosfet switch works in a soft switching state and reduces the switching loss of the Mosfet switch.