Bidirectional power distribution device for optical storage direct flexible system

Abstract

The utility model provides a bidirectional power distribution device for an optical storage direct flexible system, and belongs to the technical field of power distribution devices. The problem that a storage battery is arranged on the output side of an existing photovoltaic DC / DC converter, so that the user side direct current load power supply reliability is poor is solved. Comprising a bidirectional full-bridge inverter circuit, a DSP control circuit and switch driving amplification circuits, the high-voltage side of the bidirectional full-bridge inverter circuit is connected with a direct-current bus, the low-voltage side of the bidirectional full-bridge inverter circuit is connected with a direct-current load, and switches of the bidirectional full-bridge inverter circuit are connected with the DSP control circuit through the corresponding switch driving amplification circuits. When distributed photovoltaic power generation is insufficient or fluctuates, the bidirectional power distribution device automatically and cooperatively supplies power to the direct current load; when distributed photovoltaic power generation is sufficient, the bidirectional power distribution device automatically quits operation; when the distributed photovoltaic power generation is sufficient and the direct current load cannot be completely absorbed, redundant electric energy can be transmitted to the direct current bus through the bidirectional power distribution device and then is connected to the grid; the utility model is applied to the optical storage direct flexible system.

Description

Technical Field

[0001] The utility model provides a bidirectional power distribution device for a photovoltaic energy storage DC flexible system, belonging to the technical field of power distribution devices. Background Technique

[0002] With the rapid development of distributed photovoltaic power generation technology, relatively stable and controllable direct current can be obtained after the photovoltaic panels pass through the photovoltaic DC / DC converter. This direct current can directly supply power to the DC loads of users, solving the problem of direct local consumption of green electricity. However, due to the volatility and randomness of photovoltaic power generation itself, there will also be the above problems in the power supply of the DC loads of users. Currently, the common measure is to equip energy storage devices such as storage batteries on the output side of the photovoltaic DC / DC converter. However, this method has problems such as complex charge and discharge control of the storage battery, inability to guarantee the operation, maintenance, and safety of the storage battery, and inability to fully guarantee the reliability of the power supply to the DC loads of users. Content of the Utility Model

[0003] In order to solve the problem of poor reliability of the power supply to the DC loads on the user side when a storage battery is equipped on the output side of the existing photovoltaic DC / DC converter, the utility model provides a bidirectional power distribution device for a photovoltaic energy storage DC flexible system, which can realize that when the distributed photovoltaic power generation is insufficient or fluctuating, the bidirectional power distribution device automatically cooperates to supply power to the DC loads to ensure the normal operation of the loads; when the distributed photovoltaic power generation is sufficient, the bidirectional power distribution device automatically exits the operation, and the photovoltaic DC / DC conversion device supplies power to the DC loads alone; when the distributed photovoltaic power generation is sufficient and the DC loads cannot fully consume it, the excess electric energy can be sent to the DC bus through the bidirectional power distribution device and then grid-connected.

[0004] In order to solve the above technical problems, the technical solution adopted by the utility model is as follows: A bidirectional power distribution device for a photovoltaic energy storage DC flexible system includes a bidirectional full-bridge inverter circuit, a DSP control circuit, and a switch drive and amplification circuit. The high-voltage side of the bidirectional full-bridge inverter circuit is connected to the DC bus, the low-voltage side of the bidirectional full-bridge inverter circuit is connected to the DC loads, each switch of the bidirectional full-bridge inverter circuit is connected to the DSP control circuit through the corresponding switch drive and amplification circuit. The DSP control circuit is used to generate PWM drive signals for each switch in the bidirectional full-bridge inverter circuit, and collect the voltage and current on the high-voltage side and the voltage and current on the low-voltage side of the full-direction full-bridge inverter circuit. The switch drive and amplification circuit is used to amplify the drive signals of each switch generated by the DSP control circuit.

[0005] The bidirectional full-bridge inverter circuit includes four high-voltage-side full-bridge inverter switches Q1, Q2, Q3, and Q4, four low-voltage-side full-bridge inverter switches Q5, Q6, Q7, and Q8, and a high-frequency isolation transformer T1. The input end Ui of the high-voltage-side full-bridge inverter circuit is connected to the high-voltage input end of the DC bus, and high-voltage-side filter capacitors C1 are also connected on both sides of the input end Ui. The high-voltage-side full-bridge inverter circuit and the low-voltage-side full-bridge inverter circuit achieve step-up / step-down and electrical isolation through the high-frequency isolation transformer T1. A DC-blocking capacitor C3 is also connected between the high-voltage-side full-bridge inverter circuit and the high-frequency isolation transformer T1. The output end Uo of the low-voltage-side full-bridge inverter circuit is connected to the DC load, and a filter inductor L1 is also connected to the output end of the low-voltage-side full-bridge inverter circuit. A protection switch Q9 is connected in parallel at both ends of the filter inductor L1.

[0006] The AN0-AN3 ports of the DSP control circuit are respectively connected to the high-voltage-side voltage sampling signal Ui, the low-voltage-side voltage sampling signal Uo, the high-voltage-side current sampling signal Ii, and the low-voltage-side current sampling signal Io. Nine PWM ports of the DSP control circuit are set to output drive signals for the switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, and Q9 respectively.

[0007] The switch drive amplifier circuit includes an optocoupler. The optocoupler includes a light-emitting diode, a triode, and a MOSFET transistor. The positive electrode of the light-emitting diode is connected to the PWM signal through a current-limiting resistor R1, and the negative electrode of the light-emitting diode is grounded. A power supply VCC is applied to the secondary side of the optocoupler to provide a high voltage. A capacitor C7, a resistor R2, and the collector of the triode are connected in parallel to the power supply VCC. The emitter of the triode is connected to the drain of the MOSFET transistor and then in parallel with a resistor R3. The source of the MOSFET transistor is connected in parallel to one end of a capacitor C8, the positive electrode of a zener diode D1, and then grounded. The other end of the capacitor C7 is connected in parallel to the other end of the capacitor C8, the other end of the resistor R2, the negative electrode of the zener diode D1, the one end of a resistor R4, and the one end of a zener diode D2. The other end of the resistor R4 is connected in parallel to the other end of the resistor R3 and the other end of the zener diode D2, and then used as the DPWM signal output.

[0008] The DSP model adopted in the DSP control circuit is TMS320F28034.

[0009] The photovoltaic-storage-direct-current-flexible power system includes a photovoltaic power generation component, an energy storage component, a DC power distribution system, and a flexible power consumption system. The photovoltaic component is connected to the DC power distribution system and / or the flexible power consumption system. The high-voltage side of the bidirectional power distribution device is connected to the DC power distribution system, and the low-voltage side of the bidirectional power distribution device is connected to the flexible power consumption system.

[0010] The beneficial effects of the present utility model compared with the prior art are as follows: when the distributed photovoltaic power generation is insufficient or fluctuating, the bidirectional power distribution device can draw power from the DC bus and actively supply power to the DC load to ensure the normal operation of the load; when the distributed photovoltaic power generation is sufficient, the DC power distribution device automatically stops supplying power to the DC load, and the photovoltaic DC / DC conversion device alone supplies power to the DC load; when the distributed photovoltaic power generation is sufficient and the DC load cannot fully absorb it, the excess electric energy can be automatically sent to the DC bus through the bidirectional power distribution device and then connected to the grid to ensure the full absorption of photovoltaic power generation.

[0011] The present utility model also has the following advantages:

[0012] 1. The device has a high-frequency isolation transformer, which can achieve electrical isolation between the DC load and the high-voltage DC bus, improving the safety and reliability of the system;

[0013] 2. The device can automatically realize bidirectional energy flow without manual control, improving the intelligent level of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following further describes the present utility model with reference to the drawings:

[0015] Figure 1 is a schematic structural diagram of the present utility model applied to the optical storage direct soft system;

[0016] Figure 2 is a schematic diagram of the all-directional full-bridge inverter circuit of the present utility model;

[0017] Figure 3 is a schematic diagram of the DSP control circuit of the present utility model;

[0018] Figure 4 is a schematic diagram of the switch drive amplification circuit of the present utility model. SPECIFIC EMBODIMENTS

[0019] As Figures 1 to 4 shown, the present utility model provides a bidirectional power distribution device for an optical storage direct soft system. The bidirectional power distribution device is respectively connected to the DC bus and the input power supply end of the DC load in the optical storage direct soft system. The bidirectional power distribution device includes a bidirectional full-bridge inverter circuit, a DSP control circuit, and a switch drive amplification circuit, wherein the bidirectional full-bridge inverter circuit is connected to the switch drive amplification circuit, and the switch drive amplification circuit is connected to the DSP control circuit.

[0020] As Figure 2As shown in the figure, the bidirectional full-bridge inverter circuit includes four high-side full-bridge inverter switches Q1, Q2, Q3, and Q4, four low-side full-bridge inverter switches Q5, Q6, Q7, and Q8, and a high-frequency isolation transformer T1. The input end Ui of the high-side full-bridge inverter circuit is connected to the high-voltage input end of the DC bus, and high-side filter capacitors C1 are also connected on both sides of the input end Ui. The high-side full-bridge inverter circuit and the low-side full-bridge inverter circuit achieve step-up and step-down through the high-frequency isolation transformer T1, and a DC-blocking capacitor C3 is also connected between the high-side full-bridge inverter circuit and the high-frequency isolation transformer T1. The output end Uo of the low-side full-bridge inverter circuit is connected to the DC load, and a filter inductor L1 is also connected to the output end of the low-side full-bridge inverter circuit. A protection switch Q9 is connected in parallel at both ends of the filter inductor L1.

[0021] As Figure 3 shown is the schematic diagram of the DSP control circuit. The DSP model adopted is TMS320F28034, and a crystal oscillator circuit is connected to its periphery. The crystal oscillator circuit includes a crystal oscillator Y1, crystal oscillator bypass capacitors C4 and C5. The high-side voltage sample Ui is sent to the AN0 port of TMS320F28034, the low-side voltage sample Uo is sent to the AN1 port of TMS320F28034, the high-side current sample Ii is sent to the AN2 port of TMS320F28034, and the low-side current sample Io is sent to the AN3 port of TMS320F28034; PWM1, PWM2, PWM3, PWM4, PWM5, PWM6, PWM7, PWM8, and PWM9 are the drive signals of Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, and Q9 respectively; a power filter capacitor C6 is connected between the power supplies of TMS320F28034.

[0022] As Figure 4 shown is the schematic diagram of the switch drive and amplification circuit, including an optocoupler, from Figure 3The PWM1, PWM2, PWM3, PWM4, PWM5, PWM6, PWM7, PWM8, and PWM9 signals in [it] are small signals. After being amplified by an optocoupler, a large current signal is obtained to drive the MOS transistor to turn on and off. The optocoupler includes a light-emitting diode, a triode, and a MOSFET transistor. The positive electrode of the light-emitting diode is connected to the PWM signal through a current-limiting resistor R1, and the negative electrode of the light-emitting diode is grounded. A power supply VCC is externally applied to the secondary side of the optocoupler to provide a high voltage. A capacitor C7, a resistor R2, and the collector of the triode are connected in parallel to the power supply VCC. The emitter of the triode is connected to the drain of the MOSFET transistor and then in parallel with a resistor R3. The source of the MOSFET transistor is grounded after being in parallel with one end of a capacitor C8 and the positive electrode of a zener diode D1. The other end of the capacitor C7 is in parallel with the other end of the capacitor C8, the other end of the resistor R2, the negative electrode of the zener diode D1, one end of a resistor R4, and one end of a zener diode D2. The other end of the resistor R4 is in parallel with the other end of the resistor R3 and the other end of the zener diode D2 and then used as the output of the DPWM signal. Among them, the capacitors C7 and C8 are filter capacitors, the resistor R2 is the current-limiting resistor of the zener diode D1, which is used to generate a driving turn-off voltage, the resistor R3 is the driving resistor of the MOS transistor, the zener diode D2 is used to limit the voltage spike of the driving voltage, and the resistor R4 is the protection resistor of the MOS transistor.

[0023] The bidirectional power distribution device of the present utility model can be used in a photovoltaic-storage-direct-softness system, which refers to a system composed of photovoltaic power generation components, energy storage components, a DC power distribution system, and a flexible power consumption system. In the actual system composition, it mainly includes photovoltaic cells, photovoltaic converters, energy storage batteries, energy storage converters, DC buses, DC loads, and AC / DC bidirectional conversion devices. Specifically, as Figure 1 shown, the photovoltaic-storage-direct-softness system in this embodiment includes multiple photovoltaic panels, a photovoltaic DC / DC device, a DC load, an AC / DC bidirectional conversion device, a DC bus, a bidirectional power distribution device, and an energy storage bidirectional conversion device. Among them, a part of the photovoltaic panels supply power to the DC load through the photovoltaic DC / DC device, and another part of the photovoltaic panels are connected to the DC bus through the photovoltaic DC / DC device. The input end of the DC bus is connected with an AC / DC bidirectional conversion device, and an energy storage bidirectional conversion device is also connected to the DC bus. The bidirectional power distribution device is respectively connected to the DC bus and the input power supply end of the DC load in the photovoltaic-storage-direct-softness system; the photovoltaic panels supply power to the DC load through the photovoltaic DC / DC device, and the DC bus supplies power to the high-voltage side of the bidirectional power distribution device to ensure the normal voltage output of its low-voltage side. At the same time, the low-voltage side of the bidirectional power distribution device also supplies power to the DC load.

[0024] Combined with Figure 1 、 Figure 2 、 Figure 3 and Figure 4It can be known that the working principle and control process of the two-way power distribution device of the present utility model are as follows:

[0025] When the photovoltaic DC / DC device has no power output, the DC load is all powered by the two-way power distribution device;

[0026] When the output power of the photovoltaic DC / DC device is insufficient, the photovoltaic DC / DC device and the two-way power distribution device together supply power to the DC load;

[0027] When the output power of the photovoltaic DC / DC device is sufficient, it alone supplies power to the DC load, and the low-voltage side of the two-way power distribution device is in a hot standby state;

[0028] When the output power of the photovoltaic DC / DC device cannot be consumed, the two-way power distribution device automatically switches modes, supplies power from the low-voltage side, outputs from the high-voltage side, sends the low-voltage side electric energy to the DC bus, and then is connected to the grid for consumption.

[0029] Therefore, the present utility model can not only ensure the power supply reliability of the DC load, but also ensure the complete consumption of photovoltaic power generation, improving the utilization efficiency of new energy.

[0030] Regarding the specific structure of the present utility model, it should be noted that the connection relationships between the various component modules adopted by the present utility model are determined and achievable. Except for the special descriptions in the embodiments, the specific connection relationships can bring corresponding technical effects, and on the premise of not relying on the execution of corresponding software programs, solve the technical problems proposed by the present utility model. The models of the components, modules, and specific components, the connection methods between each other, and the conventional usage methods and expected technical effects brought by the above technical features, except for the specific descriptions, all belong to the publicly disclosed content in patents, journal papers, technical manuals, technical dictionaries, and textbooks that those skilled in the art can obtain before the filing date, or belong to the prior art such as the conventional technology and common general knowledge in the field, and do not need to be elaborated. This makes the technical solution provided in this case clear, complete, and achievable, and can reproduce or obtain the corresponding physical product according to this technical means.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model, rather than to limit it; although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present utility model.

Claims

1. A bidirectional power distribution device for a photovoltaic-storage-direct-current flexible system, characterized in that: The invention comprises a bidirectional full-bridge inverter circuit, a DSP control circuit and a switch drive amplifier circuit. The high-voltage side of the bidirectional full-bridge inverter circuit is connected to a DC bus, and the low-voltage side of the bidirectional full-bridge inverter circuit is connected to a DC load. Each switch of the bidirectional full-bridge inverter circuit is connected to the DSP control circuit via a corresponding switch drive amplifier circuit. The DSP control circuit is used to generate a PWM drive signal for each switch in the bidirectional full-bridge inverter circuit and collect the high-voltage side voltage, current and low-voltage side voltage and current of the bidirectional full-bridge inverter circuit. The switch drive amplifier circuit is used to amplify the drive signal of each switch generated by the DSP control circuit.

2. The bidirectional power distribution device for a solar-storage direct-flexible system according to claim 1, characterized in that: The bidirectional full-bridge inverter circuit includes four high-voltage side full-bridge inverter switches Q1, Q2, Q3 and Q4, four low-voltage side full-bridge inverter switches Q5, Q6, Q7 and Q8, and a high-frequency isolation transformer T1, wherein the input end Ui of the high-voltage side full-bridge inverter circuit is connected to the high-voltage input end of the DC bus, and the high-voltage side filter capacitor C1 is also connected on both sides of the input end Ui. The high-voltage side full-bridge inverter circuit and the low-voltage side full-bridge inverter circuit are buck-boosted and electrically isolated through the high-frequency isolation transformer T1, and a DC isolation capacitor C3 is also connected between the high-voltage side full-bridge inverter circuit and the high-frequency isolation transformer T1. The output end Uo of the low-voltage side full-bridge inverter circuit is connected to a DC load, and the output end of the low-voltage side full-bridge inverter circuit is also connected to a filter inductor L1, and a protection switch Q9 is connected in parallel at both ends of the filter inductor L1.

3. The bidirectional power distribution device for a photovoltaic-storage-direct-current flexible system according to claim 2, characterized in that: The AN0-AN3 ports of the DSP control circuit are respectively connected to the high-voltage side voltage sampling Ui, the low-voltage side voltage sampling Uo, the high-voltage side current sampling Ii and the low-voltage side current sampling Io signals, and the PWM port of the DSP control circuit is set to 9 drive signals for output switches Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 and Q9 respectively.

4. The two-way power distribution device for a photovoltaic-storage-direct-current flexible system according to claim 1, characterized in that: The switch drive amplifier circuit includes an optocoupler, which includes a light-emitting diode, a transistor, and a MOSFET transistor. The anode of the light-emitting diode is connected to the PWM signal via a current-limiting resistor R1, and the cathode of the light-emitting diode is grounded. A power supply VCC is applied to the secondary side of the optocoupler to provide a high voltage. A capacitor C7, a resistor R2, and the C electrode of the transistor are connected in parallel to the power supply VCC. The E electrode of the transistor is connected to the D electrode of the MOSFET transistor and then to the resistor R3 in parallel. The S electrode of the MOSFET transistor is connected in parallel to one end of the capacitor C8 and the anode of the voltage-stabilizing diode D1 and then to ground. The other end of the capacitor C7 is connected in parallel to the other end of the capacitor C8, the other end of the resistor R2, the cathode of the voltage-stabilizing diode D1, one end of the resistor R4, and one end of the voltage-stabilizing diode D2. The other end of the resistor R4 is connected in parallel to the other end of the resistor R3 and the other end of the voltage-stabilizing diode D2 to output as a DPWM signal.

5. The two-way power distribution device for a photovoltaic-storage-direct-current flexible system according to claim 3, wherein: The DSP model used in the DSP control circuit is TMS320F28034.

6. A bidirectional power distribution device for a solar-storage direct-flexible system according to any one of claims 1 to 5, characterized in that: The photovoltaic-storage-direct-flexible system includes a photovoltaic power generation component, a energy storage component, a DC power distribution system, and a flexible power consumption system. The photovoltaic power generation component is connected to the DC power distribution system and / or the flexible power consumption system. The high-voltage side of the bidirectional power distribution device is connected to the DC power distribution system, and the low-voltage side of the bidirectional power distribution device is connected to the flexible power consumption system.

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