阅读说明：本技术 一种双有源桥dc/dc变换器软充控制系统及方法 (Soft charging control system and method for double-active-bridge DC/DC converter ) 是由 唐德平 于 2020-04-17 设计创作，主要内容包括：一种双有源桥DC/DC变换器软充控制系统,涉及电力电子技术领域,解决变换器启动过程中冲击电流大的问题,包括前级单相H桥式逆变器、后级单相H桥式整流器、单相高频变压器、变压器漏感；单相高频变压器连接于前级单相H桥式逆变器与后级三相H桥式整流器之间；变压器漏感连接于前级单相H桥式逆变器与单相高频变压器之间；尖峰电流移相调制驱动系统以及脉冲闭锁控制系统用于变换器的软启动；减少了开关管承受的冲击电流和变压器的励磁涌流,延长开关管和变压器的使用寿命；控制方法步骤清晰简单,易于实现。(A soft charging control system of a double-active-bridge DC/DC converter relates to the technical field of power electronics, solves the problem of large impact current in the starting process of the converter, and comprises a front-stage single-phase H-bridge inverter, a rear-stage single-phase H-bridge rectifier, a single-phase high-frequency transformer and a transformer leakage inductance; the single-phase high-frequency transformer is connected between the front-stage single-phase H bridge inverter and the rear-stage three-phase H bridge rectifier; the transformer leakage inductance is connected between the preceding-stage single-phase H bridge inverter and the single-phase high-frequency transformer; the peak current phase-shift modulation driving system and the pulse locking control system are used for soft start of the converter; the impact current born by the switching tube and the excitation surge current of the transformer are reduced, and the service lives of the switching tube and the transformer are prolonged; the control method has clear and simple steps and is easy to realize.)

1. A soft charging control system of a double-active-bridge DC/DC converter is characterized by comprising a front-stage single-phase H-bridge inverter, a rear-stage single-phase H-bridge rectifier, a single-phase high-frequency transformer T and a transformer leakage inductor L_sThe single-phase high-frequency transformer T is connected between the front-stage single-phase H-bridge inverter and the rear-stage three-phase H-bridge rectifier, and the leakage inductance L of the transformer_sThe single-phase high-frequency transformer T is connected between the front-stage single-phase H bridge inverter and the single-phase high-frequency transformer T; the double-active-bridge DC/DC converter soft charging control system also comprises a peak current phase-shift modulation driving system and a pulse locking control system, and is used for soft start of the converter; the peak current phase-shift modulation driving system is used for controlling the on-off of a switching tube of the preceding-stage single-phase H-bridge inverter; the pulse locking control system is used for controlling the on-off of a switching tube of the rear-stage single-phase H-bridge rectifier.

2. The system as claimed in claim 1, wherein the pre-stage single-phase H-bridge inverter comprises an input source u_inA first switch tube S₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄(ii) a The input source u_inProviding a power supply for a preceding-stage single-phase H-bridge inverter; the first switch tube S₁A second switch tube S₂An upper half bridge arm and a lower half bridge arm which respectively form a first bridge arm of the preceding-stage single-phase H-bridge inverter; the third switch tube S₃And a fourth switching tube S₄And the upper half bridge arm and the lower half bridge arm of the second bridge arm of the preceding-stage single-phase H-bridge inverter are formed.

3. The dual active bridge DC/DC converter soft charge control of claim 2The system is characterized in that the rear-stage single-phase H-bridge rectifier comprises an output source u_oAn output capacitor C and a fifth switch tube S₅The sixth switching tube S₆Seventh switching tube S₇And an eighth switching tube S₈(ii) a The input source u_inProviding a power supply for a preceding-stage single-phase H-bridge inverter; the fifth switch tube S₅The sixth switching tube S₆The upper half bridge arm and the lower half bridge arm form a first bridge arm of the preceding-stage single-phase H-bridge inverter; the seventh switch tube S₇And an eighth switching tube S₈And the upper half bridge arm and the lower half bridge arm of the second bridge arm of the preceding-stage single-phase H-bridge inverter are formed.

4. The dual-active-bridge DC/DC converter soft charging control system according to claim 3, wherein the switch tube is an insulated gate bipolar transistor or an electric field effect transistor.

5. The dual-active-bridge DC/DC converter soft charging control system according to claim 4, wherein the duty ratio of the driving pulse of the pulse locking control system in the whole driving period is 0; the fifth switch tube S of the rear-stage single-phase H-bridge rectifier₅The sixth switching tube S₆Seventh switching tube S₇And an eighth switching tube S₈Is in the off state for the entire driving period.

6. The dual-active-bridge DC/DC converter soft charge control system according to claim 5, wherein the spike current phase shift modulation driving system comprises a subtracter (1), a PI regulator (2), an adder (3), a phase shift modulator (4) and an inverter (5); the subtracter (1), the PI regulator (2), the adder (3) and the phase-shift modulator (4) are sequentially connected in series; the subtracter (1) gives a given sustainable current command value I_rCollected current peak value i of primary side of single-phase high-frequency transformer T_peakPerforming difference to obtain a current error signal delta i; the calculation formula of the current error signal Δ i is as follows:

Δi＝I_r-i_peakformula (1)

Sending the current error signal delta i into a PI regulator (2), and outputting to obtain a phase shift angle variable quantity delta d; the adder (3) shifts the phase angle d of the previous period^kAdding the phase shift angle variable quantity delta d to obtain the phase shift angle d of the period^k+1(ii) a The phase shift angle d of the cycle^k+1The calculation formula of (a) is as follows:

d^k+1＝d^k+ Δ d formula (2)

Shifting the phase of the current period by a phase angle d^k+1Sending the signal into a phase-shift modulator (4) to generate a first switching tube S of a preceding-stage single-phase H bridge type inverter₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄The drive pulse of (1); the phase-shift modulator (4) is controlled by a phase-shift angle with a fixed duty ratio, and the duty ratio is a fixed value of 0.5; the first switch tube S₁And a third switching tube S₃The conduction phase shift angle between them is the phase shift angle d of the cycle^k+1Then, the first switch tube S is connected₁And a third switching tube S₃The driving pulses are respectively sent into the inverter (5) to respectively obtain a second switching tube S₂And a fourth switching tube S₄The drive pulse of (1); controlling the front-stage single-phase H-bridge inverter of the primary side of the single-phase high-frequency transformer T to transmit power to the rear-stage single-phase H-bridge rectifier of the secondary side of the single-phase high-frequency transformer T, charging the output capacitor C of the rear-stage single-phase H-bridge rectifier of the secondary side of the single-phase high-frequency transformer T to the nominal voltage V of the output capacitor C_CThereafter, the charging process ends.

7. A control method applied to the double-active-bridge DC/DC converter soft charging control system of any one of claims 1 to 6 is characterized by comprising the following steps:

step 1: pulse lock control of a switching tube of a rear-stage single-phase H-bridge rectifier; the method specifically comprises the following steps: the duty ratio of the driving pulse of the pulse locking control system in the whole driving period is 0; the fifth switch tube S of the rear-stage single-phase H-bridge rectifier₅The sixth switching tube S₆Seventh switching tube S₇And an eighth switching tube S₈In the wholeAll are in a closed state in a driving period;

step 2: the method comprises the steps that a given bearable current instruction value is differed with a collected current peak value of a primary side of the single-phase high-frequency transformer to obtain a current error signal; the method specifically comprises the following steps: the subtracter (1) gives a given sustainable current command value I_rCollected current peak value i of primary side of single-phase high-frequency transformer T_peakPerforming difference to obtain a current error signal delta i; the calculation formula of the current error signal Δ i is as follows:

Δi＝I_r-i_peakformula (1)

And step 3: obtaining the phase shift angle variation from the current error signal; the method specifically comprises the following steps: sending the current error signal delta i to a PI regulator (2), and outputting to obtain a phase shift angle variable delta d;

and 4, step 4: adding the phase shift angle of the previous period and the phase shift angle variable quantity to obtain the phase shift angle of the period; the method specifically comprises the following steps: the adder (3) shifts the phase angle d of the previous period^kAdding the phase shift angle variable quantity delta d to obtain the phase shift angle d of the period^k+1(ii) a The phase shift angle d of the cycle^k+1The calculation formula of (a) is as follows:

d^k+1＝d^k+ Δ d formula (2)

And 5: generating a switching tube driving pulse to control the converter to be in soft charging; the method specifically comprises the following steps: shifting the phase of the current period by a phase angle d^k+1Sending the signal into a phase-shift modulator (4) to generate a first switching tube S of a preceding-stage single-phase H bridge type inverter₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄The drive pulse of (1); the phase-shifting modulator (4) is controlled by a phase-shifting angle with a fixed duty ratio; the first switch tube S₁And a third switching tube S₃The conduction phase shift angle between them is the phase shift angle d of the cycle^k+1Then, the first switch tube S is connected₁And a third switching tube S₃The driving pulses are respectively sent into the inverter (5) to respectively obtain a second switching tube S₂And a fourth switching tube S₄The drive pulse of (1); single-phase H bridge rectifier for controlling front-stage single-phase H bridge inverter of single-phase high-frequency transformer T primary side to rear-stage single-phase H bridge inverter of single-phase high-frequency transformer T secondary sideThe current transformer transmits power and charges an output capacitor C of a rear-stage single-phase H-bridge rectifier on the secondary side of the single-phase high-frequency transformer T; charging the secondary output capacitor C of the single-phase high-frequency transformer T to the nominal voltage V_CThereafter, the charging process ends.

8. The method as claimed in claim 7, wherein the constant duty cycle in step 5 is a constant value of 0.5.

Technical Field

The invention belongs to the technical field of power electronics, and relates to a soft charging control system and method for a double-active-bridge DC/DC converter.

Background

With the increasing environmental and energy problems, the use of renewable energy is strongly promoted by countries worldwide. Since renewable energy is greatly influenced by weather and intermittent, a hybrid power supply system is generally formed with an energy storage system. The double-active-bridge DC-DC converter has the advantages of bidirectional power flow, input and output isolation, high power density, ZVS (zero voltage switching) soft switch and the like, becomes a bridge for connecting the renewable energy power generation system and the energy storage system, and improves the power supply stability.

However, the double-active bridge DC-DC converter may cause a large impact current in the starting process, which may not only cause damage to the switching device, but also reduce the service life; and excitation inrush current of the transformer can be caused, the current can be 8-30 times of rated current of the transformer, and the safe operation of the system is seriously influenced.

Disclosure of Invention

The invention aims to solve the technical problem of how to reduce the impact current of the double-active-bridge DC/DC converter in the starting process.

The invention solves the technical problems through the following technical scheme.

A soft charging control system of a double-active-bridge DC/DC converter comprises a front-stage single-phase H-bridge inverter, a rear-stage single-phase H-bridge rectifier, a single-phase high-frequency transformer T and a transformer leakage inductor L_sThe single-phase high-frequency transformer T is connected between the front-stage single-phase H-bridge inverter and the rear-stage three-phase H-bridge rectifier, and the leakage inductance L of the transformer_sThe single-phase high-frequency transformer T is connected between the front-stage single-phase H bridge inverter and the single-phase high-frequency transformer T; the double-active bridge DC/DC converter soft charging control system also comprises a peak current phase-shift modulation driving system and a pulse locking control system,soft start for the converter; the peak current phase-shift modulation driving system is used for controlling the on-off of a switching tube of the preceding-stage single-phase H-bridge inverter; the pulse locking control system is used for controlling the on-off of a switching tube of the rear-stage single-phase H-bridge rectifier.

According to the soft charging control system of the double-active-bridge DC/DC converter, the front-stage single-phase H-bridge inverter is driven by adopting peak current phase shift modulation, the rear-stage single-phase H-bridge rectifier is controlled by adopting pulse locking, and the front-stage single-phase H-bridge inverter and the rear-stage single-phase H-bridge rectifier are matched with each other and are charged quickly and stably by using the output capacitor, so that the soft start of the converter is; therefore, the impact current of the double-active-bridge DC/DC converter in the starting process is reduced, the impact current born by the switching tube and the magnetizing inrush current of the transformer are reduced, and the service lives of the switching tube and the transformer are prolonged.

As a further improvement of the technical scheme of the invention, the preceding-stage single-phase H-bridge inverter comprises an input source u_inA first switch tube S₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄(ii) a The input source u_inProviding a power supply for a preceding-stage single-phase H-bridge inverter; the first switch tube S₁A second switch tube S₂An upper half bridge arm and a lower half bridge arm which respectively form a first bridge arm of the preceding-stage single-phase H-bridge inverter; the third switch tube S₃And a fourth switching tube S₄And the upper half bridge arm and the lower half bridge arm of the second bridge arm of the preceding-stage single-phase H-bridge inverter are formed.

As a further improvement of the technical scheme of the invention, the rear-stage single-phase H-bridge rectifier comprises an output source u_oAn output capacitor C and a fifth switch tube S₅The sixth switching tube S₆Seventh switching tube S₇And an eighth switching tube S₈(ii) a The input source u_inProviding a power supply for a preceding-stage single-phase H-bridge inverter; the fifth switch tube S₅The sixth switching tube S₆The upper half bridge arm and the lower half bridge arm form a first bridge arm of the preceding-stage single-phase H-bridge inverter; the seventh switch tube S₇And an eighth switching tube S₈And the upper half bridge arm and the lower half bridge arm of the second bridge arm of the preceding-stage single-phase H-bridge inverter are formed.

As a further improvement of the technical scheme of the invention, the switch tube is an insulated gate bipolar transistor or an electric field effect transistor.

As a further improvement of the technical scheme of the invention, the duty ratio of the driving pulse of the pulse locking control system in the whole driving period is 0; the fifth switch tube S of the rear-stage single-phase H-bridge rectifier₅The sixth switching tube S₆Seventh switching tube S₇And an eighth switching tube S₈Is in the off state for the entire driving period.

As a further improvement of the technical scheme of the invention, the peak current phase-shift modulation driving system comprises a subtracter (1), a PI regulator (2), an adder (3), a phase-shift modulator (4) and an inverter (5); the subtracter (1), the PI regulator (2), the adder (3) and the phase-shift modulator (4) are sequentially connected in series; the subtracter (1) gives a given sustainable current command value I_rCollected current peak value i of primary side of single-phase high-frequency transformer T_peakPerforming difference to obtain a current error signal delta i; the calculation formula of the current error signal Δ i is as follows:

Δi＝I_r-i_peakformula (1)

Sending the current error signal delta i into a PI regulator (2), and outputting to obtain a phase shift angle variable quantity delta d; the adder (3) shifts the phase angle d of the previous period^kAdding the phase shift angle variable quantity delta d to obtain the phase shift angle d of the period^{k +1}(ii) a The phase shift angle d of the cycle^k+1The calculation formula of (a) is as follows:

d^k+1＝d^k+ Δ d formula (2)

Shifting the phase of the current period by a phase angle d^k+1Sending the signal into a phase-shift modulator (4) to generate a first switching tube S of a preceding-stage single-phase H bridge type inverter₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄The drive pulse of (1); the phase-shift modulator (4) is controlled by a phase-shift angle with a fixed duty ratio, and the duty ratio is a fixed value of 0.5; the first switch tube S₁And a third switching tube S₃Angle of conduction phase shift therebetweenIs the phase shift angle d of the cycle^k+1Then, the first switch tube S is connected₁And a third switching tube S₃The driving pulses are respectively sent into the inverter (5) to respectively obtain a second switching tube S₂And a fourth switching tube S₄The drive pulse of (1); controlling the front-stage single-phase H-bridge inverter of the primary side of the single-phase high-frequency transformer T to transmit power to the rear-stage single-phase H-bridge rectifier of the secondary side of the single-phase high-frequency transformer T, charging the output capacitor C of the rear-stage single-phase H-bridge rectifier of the secondary side of the single-phase high-frequency transformer T to the nominal voltage V of the output capacitor C_CThereafter, the charging process ends.

A control method applied to the soft charging control system of the double-active-bridge DC/DC converter is characterized by comprising the following steps:

step 1: pulse lock control of a switching tube of a rear-stage single-phase H-bridge rectifier; the method specifically comprises the following steps: the duty ratio of the driving pulse of the pulse locking control system in the whole driving period is 0; the fifth switch tube S of the rear-stage single-phase H-bridge rectifier₅The sixth switching tube S₆Seventh switching tube S₇And an eighth switching tube S₈In the closed state in the whole drive period;

step 2: the method comprises the steps that a given bearable current instruction value is differed with a collected current peak value of a primary side of the single-phase high-frequency transformer to obtain a current error signal; the method specifically comprises the following steps: the subtracter (1) gives a given sustainable current command value I_rCollected current peak value i of primary side of single-phase high-frequency transformer T_peakPerforming difference to obtain a current error signal delta i; the calculation formula of the current error signal Δ i is as follows:

Δi＝I_r-i_peakformula (1)

And step 3: obtaining the phase shift angle variation from the current error signal; the method specifically comprises the following steps: sending the current error signal delta i to a PI regulator (2), and outputting to obtain a phase shift angle variable delta d;

and 4, step 4: adding the phase shift angle of the previous period and the phase shift angle variable quantity to obtain the phase shift angle of the period; the method specifically comprises the following steps: the adder (3) shifts the phase angle d of the previous period^kWith said phase-shifting angular variationAdding the variables delta d to obtain the phase shift angle d of the cycle^k+1(ii) a The phase shift angle d of the cycle^k+1The calculation formula of (a) is as follows:

d^k+1＝d^k+ Δ d formula (2)

And 5: generating a switching tube driving pulse to control the converter to be in soft charging; the method specifically comprises the following steps: shifting the phase of the current period by a phase angle d^k+1Sending the signal into a phase-shift modulator (4) to generate a first switching tube S of a preceding-stage single-phase H bridge type inverter₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄The drive pulse of (1); the phase-shifting modulator (4) is controlled by a phase-shifting angle with a fixed duty ratio; the first switch tube S₁And a third switching tube S₃The conduction phase shift angle between them is the phase shift angle d of the cycle^k+1Then, the first switch tube S is connected₁And a third switching tube S₃The driving pulses are respectively sent into the inverter (5) to respectively obtain a second switching tube S₂And a fourth switching tube S₄The drive pulse of (1); controlling a preceding-stage single-phase H-bridge inverter on the primary side of a single-phase high-frequency transformer T to transmit power to a rear-stage single-phase H-bridge rectifier on the secondary side of the single-phase high-frequency transformer T, and charging an output capacitor C of the rear-stage single-phase H-bridge rectifier on the secondary side of the single-phase high-frequency transformer T; charging the secondary output capacitor C of the single-phase high-frequency transformer T to the nominal voltage V_CThereafter, the charging process ends.

As a further improvement of the technical solution of the present invention, the constant duty ratio in step 5 is a constant value of 0.5.

The invention has the advantages that:

(1) according to the soft charging control system of the double-active-bridge DC/DC converter, the front-stage single-phase H-bridge inverter is driven by adopting peak current phase shift modulation, the rear-stage single-phase H-bridge rectifier is controlled by adopting pulse locking, and the front-stage single-phase H-bridge inverter and the rear-stage single-phase H-bridge rectifier are matched with each other and are charged quickly and stably by using the output capacitor, so that the soft start of the converter is; therefore, the impact current of the double-active-bridge DC/DC converter in the starting process is reduced, the impact current born by the switching tube and the magnetizing inrush current of the transformer are reduced, and the service lives of the switching tube and the transformer are prolonged.

(2) The control method of the invention has clear and simple steps and is easy to realize.

Drawings

Fig. 1 is a structural diagram of a soft charging control system of a dual-active bridge DC/DC converter according to a first embodiment of the present invention;

fig. 2 is a flowchart of a control method of a dual-active-bridge DC/DC converter soft charging control system according to a second embodiment of the present invention;

fig. 3 is a driving PWM waveform diagram of each switching tube of the dual-active-bridge DC/DC converter soft charging control system according to the second embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The technical scheme of the invention is further described by combining the drawings and the specific embodiments in the specification: