Energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input

Abstract

The utility model relates to the field of circuit devices, in particular to an energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input, which comprises a first half bus capacitor C1, a second half bus capacitor C2, a capacitor C3, an inductor L1, an inductor L2, a switch tube Q1, a switch tube Q2, a switch tube Q3, a switch tube Q4, a switch tube Q5 and a switch tube Q6. Therefore, the inverter can be compatible with split-term power grid phase voltage and line voltage input, the conversion efficiency of the inverter can be improved when split-term power grid line voltage and phase voltage input is carried out, the energy storage utilization rate of a battery is improved, the problem that a bus capacitor is damaged due to overlarge surge current is effectively avoided, the working stability of the inverter is enhanced, and the service life of the inverter is prolonged. The problem that the surge current is too high when the phase voltage is connected to the energy storage grid-connected inverter is solved.

Description

Technical Field

[0001] The utility model relates to the field of circuit devices, and specifically to an energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input. Background Art

[0002] In the field of medium and small power energy storage grid-connected inverters, the Heric topology has been widely used in engineering practice due to its advantages such as low common mode current, excellent EMI characteristics, high working efficiency, and high power density. However, in a split-phase grid household environment such as the United States and Japan, in order to meet the actual demand of customers for simultaneously compatible two types of voltage inputs, namely line voltage (200 / 240Vac) and phase voltage (100 / 120Vac), the traditional Heric topology faces some challenges. When connecting to the phase voltage, due to the significant voltage difference between the bus voltage and the phase voltage, this will cause a significant increase in the inductor ripple current, and then the turn-off current of the switching tube will also increase accordingly. This not only affects the EMI characteristics of the inverter but also may cause the conduction time of some switching tubes to extend, thereby greatly increasing the conduction loss. This not only increases the heat dissipation requirement of the system but also may increase the overall cost.

[0003] To solve the above problems, the utility model proposes an energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input. By using a relay switching switch to change the circuit connection mode, it is ensured that the energy storage grid-connected inverter circuit can maintain a high conversion efficiency when connecting to the phase voltage or the line voltage, and effectively improve the utilization rate of battery energy storage. In addition, by setting a current-limiting resistor in the bus soft-start circuit, the utility model avoids potential damage to the bus capacitor caused by excessive surge current. Summary of the Utility Model

[0004] Aiming at the deficiencies of the prior art, the purpose of the utility model is to provide an energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input, which is used to overcome the above-mentioned defects in the prior art. By using a relay to change the circuit connection mode and changing the working mode of the inverter circuit according to the different voltages connected to the inverter circuit, the energy storage grid-connected inverter circuit can maintain a high inverter conversion efficiency when connecting to the phase voltage and the line voltage, improve the utilization rate of battery energy storage, and improve the safety of inverter use. By setting a current-limiting resistor in the bus soft-start circuit and controlling the closing sequence of the relay, the surge current is reduced, and the reliability of the energy storage grid-connected inverter is enhanced.

[0005] To achieve the above object, the solution provided by the present utility model is: a energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input, including a first half-bus capacitor C1 and a second half-bus capacitor C2. One end of the first half-bus capacitor C1 is connected in series with the second half-bus capacitor C2, and the other end is connected to the positive terminal of the input power supply VBUS. The other end of the second half-bus capacitor C2 is connected to the negative terminal of the input power supply VBUS;

[0006] It further includes a capacitor C3, inductors L1, L2, switching tubes Q1, Q2, Q3, Q4, Q5 and switching tube Q6;

[0007] The collector of the switching tube Q5 is connected to the connection point between the first half-bus capacitor C1 and the positive terminal of the input power supply VBUS, and the emitter is connected in series with the collector of the switching tube Q6. The emitter of the switching tube Q6 is connected to the connection point between the second half-bus capacitor C2 and the negative terminal of the input power supply VBUS. The collector of the switching tube Q1 is connected to the connection point between the first half-bus capacitor C1 and the positive terminal of the input power supply VBUS, and the emitter is connected in series with the collector of the switching tube Q2. The emitter of the switching tube Q2 is connected to the connection point between the second half-bus capacitor C2 and the negative terminal of the input power supply VBUS;

[0008] The emitter of the switching tube Q3 is connected in series with the emitter of the switching tube Q4. The collector of the switching tube Q3 is connected to the connection point between the switching tube Q1 and the switching tube Q2, and the collector of the switching tube Q4 is connected to the connection point between the switching tube Q5 and the switching tube Q6;

[0009] The inductor L1 is connected in series with the capacitor C3 and the inductor L2. One end of the inductor L1 is connected to the connection point between the switching tube Q1 and the switching tube Q2, and one end of the inductor L2 is connected to the connection point between the switching tube Q5 and the switching tube Q6;

[0010] As a further improvement of the present utility model, the energy storage grid-connected inverter circuit further includes a relay S1. One end of the relay S1 is connected to the connection point between the switching tube Q5 and the switching tube Q6, and the other end is connected to the connection point between the first half-bus capacitor C1 and the second half-bus capacitor C2.

[0011] As a further improvement of the present utility model, after the relay S1 of the energy storage grid-connected inverter circuit is closed, the switching tube Q5 and the switching tube Q6 are disconnected. The collector of the switching tube Q4 is connected to the connection point between the capacitor C1 and the capacitor C2. By controlling the opening and closing of the relay S1, the inverter circuit can be adapted to the access of two types of voltages, thereby reducing the switching loss of the switching tubes and improving the working efficiency of the inverter.

[0012] As a further improvement of the present utility model, the energy storage grid-connected inverter circuit is provided with a bus soft start circuit. The bus soft start circuit includes a bridge rectifier sub-circuit and also includes a current-limiting resistor. The current-limiting resistor includes a current-limiting resistor R1. One end of the current-limiting resistor R1 is connected to a pin of the bridge rectifier sub-circuit, and the other end is connected to the input terminal L1. The other pin of the bridge rectifier sub-circuit is connected to the connection point of the relay S3 and the input terminal L2 / N. By setting a current-limiting resistor in the bus soft start circuit, the impact of inrush current on the bus capacitor can be reduced, and the damage of the bus capacitor can be avoided.

[0013] As a further improvement of the present utility model, the energy storage grid-connected inverter circuit is also provided with a relay S2 and a relay S3. One end of the relay S2 is connected to the input terminal L1, and the other end is connected to the connection point of the inductor L1 and the capacitor C3. One end of the relay S3 is connected to the input terminal L2 / N, and the other end is connected to the connection point of the inductor L2 and the capacitor C3.

[0014] The beneficial effects of the present utility model are as follows: By using the relay S1 to switch the connection mode of the inverter circuit, the inverter circuit can be made to be compatible with split-phase grid phase voltage and line voltage input. Furthermore, when the split-phase grid line voltage and phase voltage are input, the conversion efficiency of the inverter can be improved, and the utilization rate of battery energy storage can be increased. By using this energy storage grid-connected inverter, it is possible to achieve uniform period loss distribution and meet the requirement of reducing heat dissipation, and maintain the low inductor ripple current characteristic, low switching current of the inverter and maintain good EMI characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the circuit diagram of an energy storage grid-connected inverter circuit of the present utility model that is compatible with phase voltage and line voltage input;

[0016] Figure 2 is the circuit diagram of the energy storage grid-connected inverter circuit of the present utility model after the relay S1 is closed when it is compatible with phase voltage and line voltage input;

[0017] Figure 3 is the circuit diagram of the energy storage grid-connected inverter circuit after the current-limiting resistor is connected in the second embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The specific embodiments of the present utility model will be described in detail below. It should be noted that the embodiments described here are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the following embodiments, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0019] Refer to Figures 1-3As shown in the figure, the first embodiment of the present utility model proposes a grid-connected energy storage inverter circuit compatible with phase voltage and line voltage input, which includes a first half-bus capacitor C1 and a second half-bus capacitor C2. One end of the first half-bus capacitor C1 is connected in series with the second half-bus capacitor C2, and the other end is connected to the positive terminal of the input power supply VBUS. The other end of the second half-bus capacitor C2 is connected to the negative terminal of the input power supply VBUS.

[0020] It also includes a capacitor C3, inductors L1 and L2, switching transistors Q1, Q2, Q3, Q4, Q5 and switching transistor Q6. The collector of the switching transistor Q5 is connected to the connection point between the first half-bus capacitor C1 and the positive terminal of the input power supply VBUS, and the emitter is connected in series with the collector of the switching transistor Q6. The emitter of the switching transistor Q6 is connected to the connection point between the second half-bus capacitor C2 and the negative terminal of the input power supply VBUS. The collector of the switching transistor Q1 is connected to the connection point between the first half-bus capacitor C1 and the positive terminal of the input power supply VBUS, and the emitter is connected in series with the collector of the switching transistor Q2. The emitter of the switching transistor Q2 is connected to the connection point between the second half-bus capacitor C2 and the negative terminal of the input power supply VBUS. The emitters of the switching transistors Q3 and Q4 are connected in series. The collector of the switching transistor Q3 is connected to the connection point between the switching transistors Q1 and Q2, and the collector of the switching transistor Q4 is connected to the connection point between the switching transistors Q5 and Q6. The inductor L1 is connected in series with the capacitor C3 and the inductor L2. One end of the inductor L1 is connected to the connection point between the switching transistors Q1 and Q2, and one end of the inductor L2 is connected to the connection point between the switching transistors Q5 and Q6.

[0021] In this embodiment, when the grid-connected energy storage inverter circuit is connected to the line voltage, the relay S1 is in the off state, and the SPWM modulation ratio of the grid-connected energy storage inverter circuit is within the normal range of 0.7 - 0.9. At this time, the circuit losses are evenly distributed, and the efficiency performance is good. When the grid-connected energy storage inverter circuit is connected to the phase voltage, the relay S1 is in the on state. At this time, the grid-connected energy storage inverter circuit enters the half-bridge T-type working mode, and the inverter bridge arm composed of the switching transistors Q5 and Q6 disconnects the circuit connection. Thus, it is ensured that when the input voltage is halved, the SPWM modulation ratio of the grid-connected energy storage inverter circuit still remains within the normal range, the losses of the switching transistors Q3 and Q4 are halved, and at the same time, the conduction losses of the switching transistors Q1 and Q2 are reduced, thereby improving the energy storage efficiency.

[0022] Refer to Figures 1-3 As shown in the figure, in this embodiment, the grid-connected energy storage inverter circuit further includes a relay S1. One end of the relay S1 is connected to the connection point between the switching transistors Q5 and Q6, and the other end is connected to the connection point between the first half-bus capacitor C1 and the second half-bus capacitor C2.

[0023] Refer to Figures 1-3As shown, in this embodiment, after the relay S1 of the energy storage grid-connected inverter circuit is closed, the switching transistors Q5 and Q6 are disconnected, and the collector of the switching transistor Q4 is connected to the connection point of the capacitors C1 and C2. By controlling the opening and closing of the relay S1, the inverter circuit can adapt to the access of two types of voltages, thereby reducing the switching loss of the switching transistors and improving the working efficiency of the inverter.

[0024] Referring to Figures 1-3 As shown, in the second embodiment of the present invention, an energy storage grid-connected inverter circuit provided with a bus soft start circuit is further proposed. The bus soft start circuit includes a bridge rectifier sub-circuit and also includes a current limiting resistor. The current limiting resistor includes a current limiting resistor R1. One end of the current limiting resistor R1 is connected to a pin of the bridge rectifier sub-circuit, and the other end is connected to the input terminal L1. The other pin of the bridge rectifier sub-circuit is connected to the connection point of the relay S3 and the input terminal L2 / N. By setting a current limiting resistor in the bus soft start circuit, the impact of the inrush current on the bus capacitor can be reduced, and the damage of the bus capacitor can be avoided.

[0025] Referring to Figures 1-3 As shown, in this embodiment, the energy storage grid-connected inverter circuit is further provided with a relay S2 and a relay S3. One end of the relay S2 is connected to the input terminal L1, and the other end is connected to the connection point of the inductor L1 and the capacitor C3. One end of the relay S3 is connected to the input terminal L2 / N, and the other end is connected to the connection point of the inductor L2 and the capacitor C3.

[0026] The bus soft start circuit includes a rectifier circuit and a current limiting resistor R1. One end of the current limiting resistor R1 is connected to a pin of the bridge rectifier sub-circuit, and the other end is connected to the grid voltage input terminal L1. The other pin of the bridge rectifier sub-circuit is connected to the connection point of the relay S3 and the input terminal L2 / N; after the inverter is connected to the voltage, the relays S1 and S3 are first closed. After 10 - 15 s after connection and when the bus voltage is stable, the relay S2 is then closed.

[0027] At this time, the current limiting resistor R1 can suppress the inrush current, and its principle is as follows:

[0028] When the grid voltage input terminal L2 / N is negative and the input terminal L1 is positive, the starting inrush current flows from the input terminal L1 along the line through the current limiting resistor R1, and then flows into the rectifier circuit of the bus soft start circuit. After being filtered by the rectifier circuit, it flows through the positive terminal of the input power supply VBUS, the first half bus capacitor C1, the relay S1, then through the differential mode inductor L2, and then through the relay S3, and enters the grid voltage input terminal L2 / N.

[0029] At this time, since the inrush current flows through the current limiting resistor R1, the inrush current is greatly reduced, thereby eliminating the impact of the inrush current on the bus capacitor and enhancing the reliability of the system.

[0030] The utility model provides an energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input. By using the relay S1 to switch the connection mode of the inverter, the inverter circuit can meet the requirement of being compatible with the split-phase grid phase voltage and line voltage input, and thus can improve the conversion efficiency of the inverter and the utilization rate of battery energy storage when the split-phase grid line voltage and phase voltage are input. Using this energy storage grid-connected inverter can achieve uniform period loss distribution and meet the requirement of reducing heat dissipation, and maintain the low inductance ripple current characteristic, low switching current and good EMI characteristic of the inverter. It solves the problem of excessive surge current when the energy storage grid-connected inverter is connected to the phase voltage. By setting a current-limiting resistor in the bus soft-start circuit and changing the relay start timing in the inverter according to the position of the current-limiting resistor, the magnitude of the surge current is reduced, effectively avoiding the problem of damage to the bus capacitor caused by excessive surge current and enhancing the working stability of the inverter.

[0031] The basic features, principles and advantages of the present utility model have been shown and described above. It should be noted that the present utility model is not limited by the above embodiments, but only some embodiments. Without departing from the spirit and scope of the present utility model, several improvements and supplements made are regarded as the protection scope of the present utility model.

Claims

1. A grid-connected energy storage inverter circuit compatible with phase voltage and line voltage inputs, characterized in that It includes a first half-bus capacitor C1 and a second half-bus capacitor C2. One end of the first half-bus capacitor C1 is connected in series with the second half-bus capacitor C2, and the other end is connected to the positive terminal of the input power supply VBUS. The other end of the second half-bus capacitor C2 is connected to the negative terminal of the input power supply VBUS; It further includes a capacitor C3, inductors L1, L2, switching transistors Q1, Q2, Q3, Q4, Q5 and a switching transistor Q6; The collector of the switching transistor Q5 is connected to the connection point between the first half-bus capacitor C1 and the positive terminal of the input power supply VBUS. The emitter is connected in series with the collector of the switching transistor Q6. The emitter of the switching transistor Q6 is connected to the connection point between the second half-bus capacitor C2 and the negative terminal of the input power supply VBUS. The collector of the switching transistor Q1 is connected to the connection point between the first half-bus capacitor C1 and the positive terminal of the input power supply VBUS. The emitter is connected in series with the collector of the switching transistor Q2. The emitter of the switching transistor Q2 is connected to the connection point between the second half-bus capacitor C2 and the negative terminal of the input power supply VBUS; The emitter of the switching transistor Q3 is connected in series with the emitter of the switching transistor Q4. The collector of the switching transistor Q3 is connected to the connection point between the switching transistor Q1 and the switching transistor Q2. The collector of the switching transistor Q4 is connected to the connection point between the switching transistor Q5 and the switching transistor Q6; The inductor L1 is connected in series with the capacitor C3 and the inductor L2. One end of the inductor L1 is connected to the connection point between the switching transistor Q1 and the switching transistor Q2. One end of the inductor L2 is connected to the connection point between the switching transistor Q5 and the switching transistor Q6.

2. The energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input according to claim 1, wherein The energy storage grid-connected inverter circuit further includes a relay S1. One end of the relay S1 is connected to the connection point between the switching transistor Q5 and the switching transistor Q6, and the other end is connected to the connection point between the first half-bus capacitor C1 and the second half-bus capacitor C2.

3. The energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input according to claim 1, wherein After the relay S1 of the energy storage grid-connected inverter circuit is closed, the switching transistors Q5 and Q6 are disconnected. The collector of the switching transistor Q4 is connected to the connection point between the capacitor C1 and the capacitor C2.

4. A grid-connected energy storage inverter circuit compatible with phase voltage and line voltage input according to claim 1, characterized in that, The energy storage grid-connected inverter circuit is provided with a bus soft-start circuit. The bus soft-start circuit includes a bridge rectifier sub-circuit and also includes a current-limiting resistor R1.

5. The energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input according to claim 4, wherein One end of the current-limiting resistor R1 is connected to a pin of the bridge rectifier sub-circuit, and the other end is connected to the input terminal L1. The other pin of the bridge rectifier sub-circuit is connected to the connection point between the relay S3 and the input terminal L2 / N.

6. The energy storage grid-connected inverter circuit compatible with phase voltage and line voltage input according to claim 1, characterized in that The energy storage grid-connected inverter circuit is further provided with a relay S2 and a relay S3. One end of the relay S2 is connected to the input terminal L1, and the other end is connected to the connection point between the inductor L1 and the capacitor C3. One end of the relay S3 is connected to the input terminal L2 / N, and the other end is connected to the connection point between the inductor L2 and the capacitor C3.

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