阅读说明：本技术 一种双向dc-ac变换器 (Bidirectional DC-AC converter ) 是由 胡茂 朱永生 裴轶 于 2018-06-06 设计创作，主要内容包括：本发明公开了一种双向DC-AC变换器,该双向DC-AC变换器包括第一滤波模块、功率变换模块、第二滤波模块和直流母线电容；功率变换模块包括双向导通开关单元、H桥DC/AC变换单元和控制单元；双向导通开关单元分别与第一滤波模块、H桥DC/AC变换单元、第二滤波模块和控制单元电连接,用于控制双向DC-AC变换器中能量的双向流动；直流母线电容与H桥DC/AC变换单元电连接,用于储能和提供直流母线电压；H桥DC/AC变换单元用于直流升压及交流逆变或交流整流及直流降压。本发明解决了现有的DC-AC变换器无法兼顾逆变升压和能量双向流动的问题。(the invention discloses a bidirectional DC-AC converter, which comprises a first filtering module, a power conversion module, a second filtering module and a direct current bus capacitor, wherein the first filtering module is connected with the first filtering module; the power conversion module comprises a bidirectional conduction switch unit, an H-bridge DC/AC conversion unit and a control unit; the bidirectional conduction switch unit is respectively and electrically connected with the first filtering module, the H-bridge DC/AC conversion unit, the second filtering module and the control unit and is used for controlling the bidirectional flow of energy in the bidirectional DC-AC converter; the direct current bus capacitor is electrically connected with the H-bridge DC/AC conversion unit and is used for storing energy and providing direct current bus voltage; the H-bridge DC/AC conversion unit is used for direct current boosting and alternating current inversion or alternating current rectification and direct current voltage reduction. The invention solves the problem that the existing DC-AC converter can not give consideration to both inversion and boosting and energy bidirectional flow.)

1. A bidirectional DC-AC converter is characterized by comprising a first filtering module, a power conversion module, a second filtering module and a direct current bus capacitor;

The power conversion module comprises a bidirectional conduction switch unit, an H-bridge DC/AC conversion unit and a control unit;

The bidirectional conduction switch unit is respectively and electrically connected with the first filtering module, the H-bridge DC/AC conversion unit, the second filtering module and the control unit and is used for controlling the bidirectional flow of energy in the bidirectional DC-AC converter;

The direct current bus capacitor is electrically connected with the H-bridge DC/AC conversion unit and is used for storing energy and providing direct current bus voltage;

The H bridge DC/AC conversion unit is used for direct current boosting and alternating current inversion or alternating current rectification and direct current voltage reduction;

The control unit is further electrically connected to a first input/output end located at the first filtering module, a second input/output end located at the second filtering module, the DC bus capacitor, and the H-bridge DC/AC conversion unit, and is configured to collect a first electrical signal at the first input/output end, a second electrical signal at the second input/output end, and the DC bus voltage, determine an energy flow direction in the bidirectional DC-AC converter according to the first electrical signal, the second electrical signal, and the DC bus voltage, and control the bidirectional conduction switch unit and the H-bridge DC/AC conversion unit to operate.

2. The bi-directional DC-AC converter of claim 1, wherein the H-bridge DC/AC conversion unit comprises at least two complementary bi-directional power switches, each complementary bi-directional power switch located on a leg of the H-bridge DC/AC conversion unit, each complementary bi-directional power switch comprising a pair of switching tube units conducting complementarily;

An upper switch unit in the switch units is electrically connected with a first end of the direct current bus capacitor, and a lower switch unit and a second end of the direct current bus capacitor are grounded;

The bidirectional conduction switch unit comprises at least two conduction branches, each conduction branch is electrically connected with the middle point of the corresponding bridge arm in the H-bridge DC/AC conversion unit and the second filtering module, each conduction branch is electrically connected with the first end of the first filtering module, and the second end of the second filtering module is grounded.

3. A bi-directional DC-AC converter according to claim 2, wherein each conducting branch comprises an anti-series complementary bi-directional power switch comprising a pair of said switching tube units in anti-series and complementary conduction.

4. A bi-directional DC-AC converter according to claim 3, wherein the switching tube unit comprises at least two power switching tubes connected in parallel with each other and a power diode connected in anti-parallel with the power switching tubes.

5. The bi-directional DC-AC converter according to claim 4, wherein the power switching transistor is one of an insulated gate field effect transistor, an insulated gate bipolar transistor, and a gallium nitride high electron mobility transistor, and the power diode is one of a fast recovery diode, an ultrafast recovery diode, and a Schottky diode.

6. A bidirectional DC-AC converter as claimed in claim 4 or 5, characterized in that the H-bridge DC/AC conversion unit comprises a single-phase H-bridge DC/AC conversion circuit, the bidirectional conduction switch unit comprises two of said conduction branches, and the second filter module comprises a single-phase filter circuit.

7. The bidirectional DC-AC converter of claim 6, wherein the H-bridge DC/AC conversion unit includes a first complementary bidirectional power switch including a first switching tube unit and a second switching tube unit, and a second complementary bidirectional power switch including a third switching tube unit and a fourth switching tube unit;

The drain electrode of the first switch tube unit and the drain electrode of the third switch tube unit are electrically connected with the first end of the direct current bus capacitor, the source electrode of the first switch tube unit is electrically connected with the drain electrode of the second switch tube unit, the source electrode of the third switch tube unit is electrically connected with the drain electrode of the fourth switch tube unit, and the source electrode of the second switch tube unit and the source electrode of the fourth switch tube unit are grounded.

8. A bidirectional DC-AC converter as recited in claim 7 wherein the bidirectional conduction switch unit includes a first conduction branch having a first anti-series complementary bidirectional power switch disposed thereon and a second conduction branch having a second anti-series complementary bidirectional power switch disposed thereon;

the first reverse series complementary bidirectional power switch comprises a fifth switching tube unit and a sixth switching tube unit, and the second reverse series complementary bidirectional power switch comprises a seventh switching tube unit and an eighth switching tube unit;

The source electrode of the fifth switching tube unit and the source electrode of the seventh switching tube unit are electrically connected with the first end of the first filtering module, the drain electrode of the fifth switching tube unit is electrically connected with the drain electrode of the sixth switching tube unit, the source electrode of the sixth switching tube unit and the source electrode of the first switching tube unit are electrically connected with the first end of the second filtering module, the drain electrode of the seventh switching tube unit is electrically connected with the drain electrode of the eighth switching tube unit, and the source electrode of the eighth switching tube unit and the source electrode of the third switching tube unit are electrically connected with the second end of the second filtering module.

9. The bi-directional DC-AC converter according to claim 8, wherein the first filtering module comprises a first filtering inductor and a first filtering capacitor, a first end of the first filtering inductor is used as a first end of the first filtering module, a second end of the first filtering inductor is electrically connected with a first end of the first filtering capacitor, a second end of the first filtering capacitor is grounded, and two ends of the first filtering capacitor are the first input/output end;

The second filter module comprises a second filter inductor and a second filter capacitor, the first end of the second filter inductor is used as the first end of the second filter module, the second end of the second filter inductor is electrically connected with the first end of the second filter capacitor, the second end of the second filter capacitor is used as the second end of the second filter module, and the two ends of the second filter capacitor are the second input and output ends.

10. The bi-directional DC-AC converter of claim 8, wherein the fifth and seventh switching tube units are turned off when energy in the bi-directional DC-AC converter flows from the first input/output terminal to the second input/output terminal; if the polarity of the alternating voltage at the second input end and the second output end is positive, the eighth switching tube unit is switched on, the sixth switching tube unit is switched off, the first switching tube unit and the second switching tube unit are complementarily switched on in an SPWM (sinusoidal pulse width modulation) mode with dead time, and the third switching tube unit and the fourth switching tube unit are complementarily switched on in a PWM (pulse width modulation) mode with dead time; if the polarity of the alternating voltage at the second input end and the second output end is negative, the sixth switching tube unit is switched on, the eighth switching tube unit is switched off, the first switching tube unit and the second switching tube unit are complementarily switched on in a PWM (pulse width modulation) mode with dead time, and the third switching tube unit and the fourth switching tube unit are complementarily switched on in an SPWM (sinusoidal pulse width modulation) mode with dead time;

When the energy in the bidirectional DC-AC converter flows from the second input end to the first input end, the sixth switching tube unit and the eighth switching tube unit are turned off; if the polarity of the alternating voltage at the second input end and the second output end is positive, the seventh switching tube unit is switched on, the fifth switching tube unit is switched off, the first switching tube unit and the second switching tube unit are complementarily switched on in an SPWM (sinusoidal pulse width modulation) mode with dead time, and the third switching tube unit and the fourth switching tube unit are complementarily switched on in a PWM (pulse width modulation) mode with dead time; if the polarity of the alternating voltage at the second input end and the second output end is negative, the fifth switching tube unit is switched on, the seventh switching tube unit is switched off, the first switching tube unit and the second switching tube unit are complementarily switched on in a PWM (pulse width modulation) mode with dead time, and the third switching tube unit and the fourth switching tube unit are complementarily switched on in an SPWM (sinusoidal pulse width modulation) mode with dead time.

11. the bi-directional DC-AC converter according to claim 10, wherein the control unit comprises a drive circuit, the first electrical signal comprises a first voltage, the second electrical signal comprises a second voltage and a second current;

The driving circuit is used for providing corresponding driving signals for the grids of the switching tube units in the bidirectional conduction switching unit and the H-bridge DC/AC conversion unit according to the first voltage, the second current and the direct-current bus voltage.

12. The bi-directional DC-AC converter according to claim 11, wherein the driving circuit comprises a first subtractor, an outer loop regulator, a voltage control loop short-circuiting switch, a PWM modulation circuit, a zero-crossing comparator, a phase-locked loop, a multiplier, a second subtractor, a proportional-integral regulator, an SPWM modulation circuit, and a logic combination circuit; the voltage control loop comprises a third subtractor and a voltage regulator;

The direct current bus voltage and a first reference signal are subjected to difference calculation by the first subtractor and then are sent to the outer ring regulator to obtain an amplitude reference signal of a current ring reference signal, the second voltage is subjected to unit sine signal calculation by the phase-locked loop, the amplitude reference signal and the unit sine signal are multiplied by the multiplier to obtain a first reference current signal, the first reference current signal and the second current are subjected to difference calculation by the second subtractor and then are sent to the proportional-integral regulator, and a control quantity obtained by linear combination of proportion and integral with the second voltage is subjected to the SPWM circuit to obtain a first control signal;

When the direct-current bus voltage is greater than the first reference signal, the control unit judges that energy flows from the first input/output end to the second input/output end, the voltage control loop short-circuit switch is used for short-circuiting the voltage control loop, and the amplitude reference signal passes through the PWM modulation circuit to obtain a second control signal; when the direct-current bus voltage is smaller than the first reference signal, the control unit judges that energy flows from the second input/output end to the first input/output end, the voltage control loop short-circuit switch is open, the difference between the second reference signal and the first voltage is obtained by the third subtracter and then is sent to the voltage regulator, and a second control signal is obtained by a control quantity output by the voltage regulator through the PWM modulation circuit;

The second voltage is compared with the zero-crossing comparator to obtain a third control signal, and the third control signal is a driving signal of the fifth switching tube unit, the sixth switching tube unit, the seventh switching tube unit and the eighth switching tube unit;

The first control signal, the second control signal and the third control signal pass through the logic combination circuit to obtain driving signals of the first switch tube unit, the second switch tube unit, the third switch tube unit and the fourth switch tube unit;

Wherein, the driving signal of the first switch tube unit is:The driving signal of the second switch tube unit is as follows:the driving signal of the third switching tube unit is as follows:The driving signal of the fourth switching tube unit is as follows:

Wherein m is the first control signal, d₁Is said second control signal, d₂Is the third control signal.

Technical Field

the embodiment of the invention relates to the technical field of power electronics, in particular to a bidirectional DC-AC converter.

Background

The DC/AC converter is widely applied to occasions such as motor speed regulation, distributed power generation systems, uninterruptible power supplies and the like. Conventional DC/AC converters include two broad classes, voltage source DC/AC converters and current source DC/AC converters. The alternating voltage output by the voltage source DC/AC converter is lower than the voltage of a direct current bus, and is essentially a step-down DC/AC converter, and in order to realize the function of boosting during inversion conversion, an additional boosting conversion circuit needs to be added in the circuit, so that the whole structure of the system is complex. The current source DC/AC converter is essentially a boost DC/AC converter, but can only realize unidirectional energy transmission and does not have the function of bidirectional energy transmission, and in the application occasions of a micro-grid, an energy storage system and the like, the inverter can not be used independently, and can only realize bidirectional energy transmission by being provided with a corresponding reverse energy transmission circuit, but the system becomes more complex.

At present, various DC/AC conversion circuits with boosting capability are proposed, such as: the converter circuit comprises a Z-source DC/AC converter, a differential DC/AC converter, an additive DC/AC converter, an integrated DC/AC converter and the like, but the converter circuits also cannot realize bidirectional flow of energy, and meanwhile, additional passive devices are introduced into partial circuits (such as the Z-source DC/AC converter and the additive DC/AC converter), so that the system cost, the volume and the weight are increased, and the control is complex.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a bidirectional DC-AC converter, so as to solve the problem that the existing DC-AC converter cannot give consideration to both the inversion and boosting and the bidirectional flow of energy and the problem that the system is complex, and to simultaneously implement two functions of DC-DC conversion and DC-AC conversion, implement the bidirectional flow of energy of the DC/AC converter, and simplify the system structure.

In order to achieve the purpose, the invention adopts the following technical scheme:

The embodiment of the invention provides a bidirectional DC-AC converter, which comprises a first filtering module, a power conversion module, a second filtering module and a direct current bus capacitor, wherein the first filtering module is connected with the first filtering module;

The power conversion module comprises a bidirectional conduction switch unit, an H-bridge DC/AC conversion unit and a control unit;

The bidirectional conduction switch unit is respectively and electrically connected with the first filtering module, the H-bridge DC/AC conversion unit, the second filtering module and the control unit and is used for controlling the bidirectional flow of energy in the bidirectional DC-AC converter;

The direct current bus capacitor is electrically connected with the H-bridge DC/AC conversion unit and is used for storing energy and providing direct current bus voltage;

the H bridge DC/AC conversion unit is used for direct current boosting and alternating current inversion or alternating current rectification and direct current voltage reduction;

The control unit is further electrically connected to a first input/output end located at the first filtering module, a second input/output end located at the second filtering module, the DC bus capacitor, and the H-bridge DC/AC conversion unit, and is configured to collect a first electrical signal at the first input/output end, a second electrical signal at the second input/output end, and the DC bus voltage, determine an energy flow direction in the bidirectional DC-AC converter according to the first electrical signal, the second electrical signal, and the DC bus voltage, and control the bidirectional conduction switch unit and the H-bridge DC/AC conversion unit to operate.

The invention has the beneficial effects that: the bidirectional DC-AC converter provided by the invention can realize the boosting and inverting functions of the bidirectional DC/AC converter without a boosting conversion circuit in the circuit inverting stage and can realize the rectifying and voltage-reducing functions of the bidirectional DC/AC converter without a voltage-reducing conversion circuit in the circuit rectifying stage by matching the bidirectional conduction switch unit in the power conversion module with the H-bridge DC/AC conversion unit, namely, the two functions of DC-DC conversion and DC-AC conversion are realized simultaneously in the circuit inverting stage and the circuit rectifying stage. Meanwhile, the control of the inversion and rectification stages is completely detected and adjusted by the control unit, so that bidirectional free energy transmission and adjustment are realized, the realization cost is reduced, the application capability of the DC/AC converter in the bidirectional energy transmission occasions such as a micro-grid and an energy storage system is improved, and the DC/AC converter has high application value.

drawings

The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:

Fig. 1 is a system block diagram of a bidirectional DC/AC converter according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a single-phase bidirectional DC/AC converter according to a second embodiment of the present invention;

Fig. 3 is a schematic structural diagram of a switching tube unit Sn according to a second embodiment of the present invention;

Fig. 4 is a schematic structural diagram of another switching tube unit Sn according to a second embodiment of the present invention;

Fig. 5 is a circuit diagram of a single-phase bidirectional DC/AC converter according to a second embodiment of the present invention;

Fig. 6 is a schematic structural diagram of a driving circuit in a control unit according to a second embodiment of the present invention;

FIG. 7 is a diagram illustrating the relationship between the control signals d1, d2, m according to a second embodiment of the present invention;

Fig. 8 is an experimental waveform diagram when the voltage V1 of the first power source is 80V, the voltage V2 of the second load is 220V, and the system power P is 500W to implement the boosting and inverting functions according to the second embodiment of the present invention;

Fig. 9 is an experimental waveform diagram when the voltage V1 of the first load is 80V, the voltage V2 of the second power supply is 220V, and the system power P is 500W to implement the rectification and voltage reduction functions according to the second embodiment of the present invention;

FIG. 10 is a schematic diagram of a three-phase bidirectional DC/AC converter according to a third embodiment of the present invention;

fig. 11 is a circuit diagram of a three-phase bidirectional DC/AC converter according to a third embodiment of the present invention;

FIG. 12 is a diagram of the relationship between control signals according to the third embodiment of the present invention;

Fig. 13 is an experimental waveform diagram when the voltage V1 of the first power source is 100V, the voltage V2 of each phase of the second load is 220V, and the system power P is 1500W to implement the boosting and inverting functions according to the third embodiment of the present invention;

fig. 14 is an experimental waveform diagram of the third embodiment of the present invention when the voltage V1 of the first load is 100V, the voltage V2 of each phase of the second power supply is 220V, and the system power P is 1500W, to implement the rectification and voltage reduction functions.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.