CN209767391U - high-gain bidirectional DC/DC converter suitable for energy storage system - Google Patents

Abstract

The utility model discloses a high-gain bidirectional DC/DC converter suitable for an energy storage system, comprising first and second direct current power sources, first and second inductors, first, second, third, fourth, fifth, sixth and seventh , eight switch tubes, first, second and third capacitors, transformers; the first DC power supply is connected with the first and second inductors; the first inductor is connected with the first and second switch tubes and transformers; the second inductor is connected with the third and fourth inductors The switch tube and the transformer are connected; the first switch tube is connected with the third switch tube and the first capacitor; the second switch tube is connected with the fourth switch tube and the first capacitor; the transformer is connected with the fifth, sixth and seventh switch tubes; The eighth switch tube is connected with the second and third capacitors; the seventh switch tube is connected with the eighth switch tube; the fifth switch tube is connected with the second capacitor and the second DC power supply; the sixth switch tube is connected with the third capacitor and the second DC power supply Power connection. The utility model has the advantages of high voltage gain, low current ripple and wide voltage range.

Description

A high-gain bidirectional DC/DC converter suitable for energy storage systems

technical field

The utility model relates to the technical field of direct current high-gain bidirectional conversion, in particular to a high-gain bidirectional DC/DC converter suitable for an energy storage system, which belongs to the direction of high-frequency switching power supply in the field of power electronics.

Background technique

Renewable new energy in my country has entered a period of rapid development. DC microgrids based on energy storage systems, photovoltaic power generation, wind power generation and other new energy power generation systems have attracted more and more attention from scholars. Renewable energy power generation such as photovoltaic power generation and wind power generation has the randomness of power generation time and power generation amount, and these randomness will have an impact on the access to the large power grid. Renewable energy cuts peaks and fills valleys. Since the DC bus voltage in a DC microgrid is typically 400V or more, the voltage rating of the energy storage elements is generally low, and the series connection of energy storage cells reduces reliability, a DC/DC converter with high voltage gain is required. However, the traditional isolated bidirectional full-bridge DC/DC converter only relies on adjusting the turns ratio of the transformer to achieve high gain, which has the disadvantages of narrow voltage variable range, large energy storage side current ripple and complicated control. Some scholars have proposed an isolated current-mode bidirectional DC/DC converter, which broadens the voltage range and reduces the current ripple by interleaving. Therefore, research on high-gain bidirectional DC/DC converters suitable for energy storage systems is of great significance for energy storage systems in DC microgrids.

Utility model content

The purpose of the utility model is to solve the problems that the existing isolated bidirectional DC/DC converters suitable for energy storage systems cannot achieve soft switching in a wide voltage range, large current ripple, and complicated control due to the coupling of multiple control variables. A high-gain bidirectional DC/DC converter suitable for energy storage systems.

In order to achieve the above purpose, the technical solution provided by the present utility model is: a high-gain bidirectional DC/DC converter suitable for an energy storage system, comprising a first DC power supply, a first inductance, a second inductance, a first The switch tube and its anti-parallel diode and parasitic capacitance, the second switch tube and its anti-parallel diode and parasitic capacitance, the third switch tube and its anti-parallel diode and parasitic capacitance, the fourth switch tube and its anti-parallel diode and parasitic capacitance, The first capacitor, the leakage inductance of the transformer and the equivalent terminal of the same name in series with the primary side and the excitation inductance of the parallel side of the secondary side, the fifth switch tube and its anti-parallel diode and parasitic capacitance, the sixth switch tube and its anti-parallel diode and parasitic capacitance , the seventh switch tube and its anti-parallel diode and parasitic capacitance, the eighth switch tube and its anti-parallel diode and parasitic capacitance, the second capacitor, the third capacitor, the second DC power supply; wherein, the first DC power supply The positive pole is respectively connected to one end of the first inductor and one end of the second inductor, and the other end of the first inductor is respectively connected to the source of the first switch tube, the drain of the second switch tube, and the primary side of the transformer with the same name in series. The other end of the second inductance is connected to the source of the third switch tube, the drain of the fourth switch tube, and the synonymous terminal of the primary side of the transformer, and the drain of the first switch tube is respectively It is connected to the drain of the third switch tube and the positive pole of the first capacitor, the source of the second switch tube is respectively connected to the source of the fourth switch tube and the negative pole of the first capacitor, and the same name terminal of the secondary side of the transformer It is respectively connected with the source of the fifth switch tube, the drain of the sixth switch tube, and the drain of the seventh switch tube, and the synonymous terminal of the secondary side of the transformer is respectively connected with the drain of the eighth switch tube and the drain of the second capacitor. The negative electrode and the positive electrode of the third capacitor are connected, the source electrode of the seventh switch tube is connected to the source electrode of the eighth switch tube, and the drain electrode of the fifth switch tube is respectively connected with the positive electrode of the second capacitor and the source electrode of the second DC power supply. The positive pole is connected, and the source pole of the sixth switch tube is respectively connected to the negative pole of the third capacitor and the negative pole of the second DC power supply.

Further, the first switch tube and the second switch tube, the third switch tube and the fourth switch tube, the fifth switch tube and the seventh switch tube, the sixth switch tube and the eighth switch tube are respectively complementary conducting, and all the The phase difference between the first switch tube and the fourth switch tube, the fifth switch tube and the sixth switch tube is 180°, and the phase difference between the first switch tube and the fifth switch tube is the phase shift angle And between -90° and 90°, the duty ratios D of the second switch tube, the fourth switch tube, the seventh switch tube, and the eighth switch tube are the same and greater than 0.5.

Further, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube are powers with reverse conduction characteristics turning tube.

Further, the turns ratio of the primary and secondary sides of the transformer is n:1, where n is the quotient of the number of turns on the primary side of the transformer divided by the number of turns on the secondary side.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

1. The voltage steady-state gain is By adjusting the turns ratio of the transformer reasonably, the converter can have the desired high voltage gain.

2. The first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube can all achieve zero-voltage turn-on, which can reduce switching losses and electromagnetic interference.

3. The voltage stress of the seventh switch tube and the eighth switch tube is only half of that of the second DC power supply, which not only reduces the cost of the circuit, but is also suitable for high voltage applications.

4. The alternating currents of the first inductor and the second inductor can reduce the current source ripple of the first DC power source and improve the service life of the energy storage battery as the first DC power source.

Description of drawings

FIG. 1 is a circuit diagram of a high-gain bidirectional DC/DC converter suitable for an energy storage system according to the present invention.

Figure 2 shows the voltage and current waveforms of the main components of the circuit in one switching cycle.

Figure 3a is one of the circuit modal diagrams of the circuit in one switching cycle.

Figure 3b is the second circuit modal diagram of the circuit in one switching cycle.

FIG. 3c is the third circuit modal diagram of the circuit in one switching cycle.

FIG. 3d is the fourth circuit modal diagram of the circuit in one switching cycle.

FIG. 3e is the fifth circuit modal diagram of the circuit in one switching cycle.

Fig. 3f is the sixth circuit modal diagram of the circuit in one switching cycle.

FIG. 3g is the seventh circuit modal diagram of the circuit in one switching cycle.

FIG. 3h is the eighth circuit modal diagram of the circuit in one switching cycle.

Figure 3i is the ninth circuit modal diagram of the circuit in one switching cycle.

Fig. 3j is the tenth circuit modal diagram of the circuit in one switching cycle.

Detailed ways

The high-gain bidirectional DC/DC converter of the present invention suitable for an energy storage system will be further described below with reference to specific implementation cases.

Referring to FIG. 1 , the high-gain bidirectional DC/DC converter suitable for the energy storage system provided by this embodiment includes a first DC power supply V ₁ , a first inductor L ₁ , a second inductor L ₂ , a first DC power source V 1 , a second inductor L 2 , and a second inductor L 2 . A switch _{Q1a and its antiparallel diode D1a and} parasitic capacitance _C1a , a second switch Q1 and its antiparallel diode D1 and parasitic capacitance _C1 , _a third switch _Q2a and its _antiparallel diode _D2a and the parasitic capacitance C _2a , the fourth switch tube Q ₂ and its anti-parallel diode D ₂ and the parasitic capacitance C ₂ , the first capacitance C _C , the transformer T and its equivalent terminal leakage inductance L _r and the secondary side in series The excitation inductance L _m in parallel, the fifth switch _{S1 and its anti-parallel diode D s1 and} parasitic capacitance C _s1 , the sixth switch S ₂ and its anti-parallel diode D _s2 and parasitic capacitance C _s2 , the seventh switch S ₃ and its anti-parallel diode D _s3 and parasitic capacitance C _s3 , the eighth switch tube S ₄ and its anti-parallel diode D _s4 and parasitic capacitance C _s4 , the second capacitance C _u , the third capacitance C _d , the second DC power supply V ₂ ; wherein, the positive pole of the _first DC power supply V1 is respectively connected to one end of the first inductance L1 and _one end of the _second inductance L2, and the other end of the _first inductance L1 is respectively connected to the first switch tube _Q1a The source of the second switch tube Q1, the drain _of the second switch tube Q1, and the equivalent terminal leakage inductance _Lr of the same name connected in series with the primary side of the transformer T are connected, and the other end of the _second inductance L2 is respectively connected to the source of the third switch tube _Q2a , The drain of the fourth switch tube _Q2 is connected to the synonymous terminal of the primary side of the transformer T, the drain of the first switch tube _Q1a is connected to the drain of the third switch tube _Q2a and the positive pole of the first capacitor C _C respectively, _The source of the second switch tube Q1 is respectively connected to the source of the fourth switch tube _Q2 and the negative pole of the first capacitor _CC , and the same-named terminal of the secondary side of the transformer T is respectively connected to the source _of the fifth switch tube S1, the _The drain of the six switch tube S2 and the drain _of the seventh switch tube S3 are connected, and the synonymous terminal of the secondary side of the transformer T is respectively connected with the drain of the eighth switch tube _S4 , the negative pole of the second capacitor C _u , the third _The positive pole of the capacitor C _d is connected, the source of the seventh switch S3 is connected to the source _of the eighth switch S4, the drain _of the fifth switch S1 is respectively connected to the positive pole of the second capacitor C _u , the second DC The positive pole of the power supply V ₂ is connected, and the source pole of the sixth switch tube S ₂ is respectively connected to the negative pole of the third capacitor C _d and the negative pole of the second DC power supply V ₂ .

The specific conditions of the above-mentioned high-gain bidirectional DC/DC converter suitable for the energy storage system in this embodiment are as follows:

1) Modal analysis

Fig. 2 draws out the waveform diagram of the main components under the condition of stable operation of the circuit.

The working state of the circuit will be analyzed in detail in conjunction with Figure 3a to Figure 3j below:

a. As shown in Figure _3a before the stage θ ₀ , the _second switch Q1, the third switch _Q2a , the sixth switch S2 and the seventh switch S3 are maintained in a conducting state under the action _of the driving signal at this stage; The first switch tube Q _1a , the fourth switch tube Q ₂ , the fifth switch tube S ₁ and the eighth switch tube S ₄ are maintained in an off state under the action of the driving signal; the voltage on the primary side of the transformer T is clamped by the first capacitor C _C The bit is -V _C ; the voltage of the secondary side of the transformer T is clamped to -V ₂ /2 by the third capacitor C _d ; the current i _Lm of the excitation inductance _Lm paralleled on the secondary side of the transformer T changes from negative to positive; the primary side of the transformer T The current i _Lr of the series-connected equivalent terminal leakage inductance L _r remains unchanged; the power is transferred from the first power source V ₁ to the second power source V ₂ ; when the driving signal of the third switch _Q2a disappears, this stage ends.

b. Stages θ ₀ ~ θ ₁ are shown in Figure 3b. In this stage, the third switch transistor Q _2a is turned off under the action of the driving signal; the current i _L2 of the second inductor L ₂ and the equivalent terminal of the same name connected in series with the primary side of the transformer T leak The current i _Lr of the sense L _r charges the parasitic capacitance C _2a of the third switch tube Q _2a , and at the same time discharges the parasitic capacitance C ₂ of the fourth switch tube Q ₂ until the anti-parallel diode D ₂ of the fourth switch tube Q ₂ conducts On; when the driving signal of the fourth switch tube _Q2 arrives, this stage ends.

c. Stages θ ₁ to θ ₂ are shown in Figure 3c. In this stage, the fourth switch transistor Q ₂ is turned on at zero voltage under the action of the driving signal; the voltage on the primary side of the transformer T changes from -V _C to 0; the voltage on the secondary side of the transformer T Clamped by the third capacitor C _d and maintained at -V ₂ /2; the current i _Lm of the excitation inductance L _m connected in parallel with the secondary side of the transformer T continues to rise; the current i of the leakage inductance L _r of the equivalent terminal of the same name connected in series with the primary side of the transformer T _Lr rises _; when the driving signal of the sixth switch S2 disappears, this stage ends. At this stage, the current i _Lr expression of the equivalent terminal leakage inductance L _r of the transformer T in series with the primary side is:

d. Stages θ ₂ to θ ₃ are as shown in Figure 3d. In this stage, the sixth switch tube S ₂ is turned off under the action of the driving signal; the current i _Lm of the excitation _Lm connected in parallel with the secondary side of the transformer T is given to the sixth switch tube S ₂ The parasitic capacitance C _s2 of the eighth switch tube S ₄ is charged, and the parasitic capacitance C _s4 of the eighth switch tube S ₄ is discharged until the anti-parallel diode D _s4 of the eighth switch tube S 4 is turned on; when the drive signal of the eighth switch tube S ₄ arrives , this stage ends.

e. Stages θ ₃ to θ ₄ are shown in Figure 3e. In this stage, the eighth switch S4 is turned _on at zero voltage under the action of the driving signal; the voltage on the primary side of the transformer T is maintained at 0; the voltage on the secondary side of the transformer T is -V _2/2 becomes 0; the current i _Lm of the excitation inductance _Lm connected in parallel with the secondary side of the transformer T remains unchanged; the current i _Lr of the leakage inductance L _r of the equivalent terminal of the same name connected in series with the primary side of the transformer T is 0; when the second switch This phase ends when the drive signal to tube Q1 _disappears . At this stage, the current i _Lr expression of the equivalent terminal leakage inductance L _r of the transformer T in series with the primary side is:

i _Lr (θ)=0 (θ ₂ <θ≤θ ₄ ) (2)

f. Stages θ ₄ to θ ₅ are shown in Fig. 3f. In this stage, the second switch Q1 is turned off under the action _of the driving signal; the current i _L1 of the _first inductor L1 and the equivalent terminal of the same name connected in series with the primary side of the transformer T leak The current i _Lr of the inductor L _r charges the parasitic capacitance C ₁ of the second switch tube Q ₁ , and at the same time discharges the parasitic capacitance C _1a of the first switch tube Q _1a until the anti-parallel diode D _1a of the first switch tube Q _1a conducts. On; when the driving signal of the first switch tube _Q1a arrives, this stage ends.

g. Stages θ ₅ to θ ₆ are shown in Figure 3g. In this stage, the first switch transistor Q _1a is turned on at zero voltage under the action of the driving signal; the voltage on the primary side of the transformer T is clamped by the first capacitor C _C from 0 to V _C ; The voltage on the secondary side of the transformer T remains 0; the current i _Lm of the excitation inductance _Lm in parallel with the secondary side of the transformer T remains unchanged; the current i _Lr of the leakage inductance L _r of the equivalent terminal of the same name in series with the primary side of the transformer T increases; when This stage ends when the driving signal _of the seventh switch S3 disappears. At this stage, the current i _Lr expression of the equivalent terminal leakage inductance L _r of the transformer T in series with the primary side is:

h. Stages θ ₆ to θ ₇ are shown in Figure _3h . In this stage, the seventh switch S3 is turned off under the action of the driving signal; the current i _Lr of the leakage inductance L _r of the equivalent terminal of the same name connected in series with the primary side of the transformer T is equivalent to The secondary side charges the parasitic capacitance C _s3 of the seventh switch tube S ₃ and discharges the parasitic capacitance C _s1 of the fifth switch tube S ₁ at the same time, until the anti-parallel diode D _s1 of the fifth switch tube S ₁ is turned on; when the fifth switch tube S 1 is turned on; This stage ends when the driving signal _of the switch S1 arrives.

i. Stages θ ₇ to θ ₈ are as shown in Figure 3i. In this stage, the fifth switch S1 is turned on at zero voltage under the action _of the driving signal; the voltage on the primary side of the transformer T is clamped to V _{C by the first capacitor C C ;} the transformer The voltage on the secondary side of T is clamped by the third capacitor C _d from 0 to V ₂ /2; the current i _Lm of the excitation _Lm in parallel on the secondary side of the transformer T changes from positive to negative; The current i _Lr of the terminal leakage inductance L _r remains unchanged; the power is transferred from the first power source V ₁ to the second power source V ₂ ; when the driving signal of the first switch _Q1a disappears, this stage ends. At this stage, the current i _Lr expression of the equivalent terminal leakage inductance L _r of the transformer T in series with the primary side is:

i _Lr (θ)=i _Lr (θ ₆ ) (θ ₆ <θ≤θ ₈ ) (4)

j. After the stage _θ8 , as shown in Figure 3j, the first switch tube Q _1a is turned off under the action of the driving signal at this stage; the current i _L1 of the first inductor L ₁ and the equivalent terminal leakage inductance L of the same name connected in series with the primary side of the transformer T The current i _Lr of _r charges the parasitic capacitance C _1a of the first switch transistor Q _1a and discharges the parasitic capacitance C ₁ of the second switch transistor Q ₁ until the anti-parallel diode D ₁ of the second switch transistor Q ₁ is turned on.

Since the primary and secondary side structures are all symmetrical, the second half cycle after this will cycle, and the remaining states will not be described in detail.

2) Steady state gain

Under the action of the interleaved parallel Boost circuit, the voltage amplitude u _ab of the primary side of the transformer T is:

The secondary side is a T-type midpoint clamp circuit, so its voltage amplitude u _cd is:

Since the transformation ratio of the transformer T is n, and the topology has the function of voltage matching on both sides of the transformer, there are:

u _ab = nu _cd (7)

According to equations (5), (6) and (7), the steady-state gain M is:

3) The current ripple of the first power supply V ₁

Since the parameters of the _first inductance L1 and the _second inductance L2 are the same, and the symmetrical double Boost topology in interleaved parallel is used, the real-time current waveforms of the _first inductance L1 and the second inductance L2 are _two waveforms with a phase difference of 180°. Taking the second inductor L ₂ as an example below, its average current effective value is:

When the fourth switch tube _Q2 is turned on, the voltage of the _second inductor L2 is clamped by the _first power supply V1, and the current begins to rise. During this period, the instantaneous value of the current of the _second inductor L2 is:

When the fourth switch tube Q ₂ is turned off, the voltage on both sides of the second inductor L ₂ is -V ₁ , and the current begins to decrease. During this period, the instantaneous value of the current of the second inductor L ₂ is:

According to the principle of volt-second balance, the current ripples Δi _L1 and Δi _L2 of the first inductor L ₁ and the second inductor L ₂ and the total input current ripple Δi are:

where T _s is the switching period.

It can be found that when D is 0.5, the current ripple of the total input current is 0. When D is not 0.5, the input current ripple frequency is twice the switching frequency, and the amplitude is much smaller than that of the single-inductance boost converter, which can affect the life of the energy storage element on the V1 side of the _first power supply. Play a very good protective effect.

The above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of implementation of the present invention. Therefore, any changes made according to the shape and principle of the present invention shall be covered by the protection of the present invention. within the range.

Claims (4)

1. A high-gain bi-directional DC/DC converter suitable for use in an energy storage system, comprising: comprises a first DC power supply (V)₁) First inductance (L)₁) Second inductance (L)₂) First switch tube (Q)_1a) And its anti-parallel diode (D)_1a) And parasitic capacitance (C)_1a) Second switch tube (Q)₁) And its anti-parallel diode (D)₁) And parasitic capacitance (C)₁) A third switching tube (Q)_2a) And its anti-parallel diode (D)_2a) And parasitic capacitance (C)_2a) Fourth switch tube (Q)₂) And its anti-parallel diode (D)₂) And parasitic capacitance (C)₂) First capacitance (C)_C) Transformer (T) and its primary side series equivalent homonymous terminal leakage inductance (L)_r) Excitation inductance (L) in parallel with secondary side_m) Fifth switching tube (S)₁) And its anti-parallel diode (D)_s1) And parasitic capacitance (C)_s1) Sixth switching tube (S)₂) And its anti-parallel diode (D)_s2) And parasitic capacitance (C)_s2) Seventh switching tube (S)₃) And its anti-parallel diode (D)_s3) And parasitic capacitance (C)_s3) The eighth switching tube (S)₄) And its anti-parallel diode (D)_s4) And parasitic capacitance (C)_s4) A second capacitance (C)_u) Third capacitance (C)_d) Second direct current power supply (V)₂) (ii) a Wherein the first DC power supply (V)₁) Is turning toThe poles are respectively connected with the first inductor (L)₁) One terminal of (a), a second inductance (L)₂) Is connected to said first inductor (L)₁) Respectively with the first switching tube (Q)_1a) Source electrode, second switch tube (Q)₁) Equivalent homonymous terminal leakage inductance (L) of the drain electrode and the primary side of the transformer (T) in series connection_r) Connected, the second inductance (L)₂) The other end of the first and second switching tubes (Q) are respectively connected with a third switching tube (Q)_2a) Source electrode, fourth switching tube (Q)₂) Is connected with the different name end of the primary side of the transformer (T), and the first switching tube (Q)_1a) Respectively with a third switching tube (Q)_2a) Drain electrode, first capacitor (C)_C) The positive pole of the second switching tube (Q)₁) With the fourth switching tube (Q) respectively₂) Source electrode, first capacitor (C)_C) Is connected with the negative pole of the transformer (T), and the homonymous ends of the secondary side of the transformer (T) are respectively connected with the fifth switch tube (S)₁) Source electrode of (1), sixth switching tube (S)₂) Drain electrode of (1), seventh switching tube (S)₃) Is connected with the drain electrode of the transformer (T), and the different name ends of the secondary side of the transformer (T) are respectively connected with the eighth switching tube (S)₄) Drain electrode of (1), second capacitor (C)_u) Negative electrode of (2), third capacitor (C)_d) The positive pole of the seventh switching tube (S)₃) Source electrode of (1) and eighth switching tube (S)₄) Is connected to the source of the fifth switching tube (S)₁) Respectively with a second capacitor (C)_u) Positive electrode of (2), second direct current power supply (V)₂) The positive pole of the sixth switching tube (S)₂) Respectively with a third capacitor (C)_d) Negative pole of (2), second direct current power supply (V)₂) Is connected to the negative electrode of (1).

2. A high gain bi-directional DC/DC converter suitable for use in an energy storage system as claimed in claim 1, wherein: the first switch tube (Q)_1a) And a second switching tube (Q)₁) And a third switching tube (Q)_2a) And a fourth switching tube (Q)₂) And a fifth switching tube (S)₁) And a seventh switching tube (S)₃) And a sixth switching tube (S)₂) And an eighth switching tube (S)₄) Respectively complementarily turned on, and the first switching tube (Q)_1a) And a fourth switching tube (Q)₂) And a fifth switching tube (S)₁) And a sixth switching tube (S)₂) 180 DEG phase difference, the first switch tube (Q)_1a) And a fifth switching tube (S)₁) Is phase shift angleAnd between-90 DEG and 90 DEG, the second switching tube (Q)₁) And a fourth switching tube (Q)₂) And a seventh switching tube (S)₃) And the eighth switching tube (S)₄) Is the same and greater than 0.5.

3. A high gain bi-directional DC/DC converter suitable for use in an energy storage system as claimed in claim 1, wherein: the first switch tube (Q)_1a) A second switch tube (Q)₁) And a third switching tube (Q)_2a) And a fourth switching tube (Q)₂) And a fifth switching tube (S)₁) And a sixth switching tube (S)₂) And a seventh switching tube (S)₃) And an eighth switching tube (S)₄) The power switch tube has reverse conducting characteristic.

4. A high gain bi-directional DC/DC converter suitable for use in an energy storage system as claimed in claim 1, wherein: the turn ratio of the primary side and the secondary side of the transformer (T) is n:1, wherein n is the quotient of the number of primary turns of the transformer (T) divided by the number of secondary turns.