WO2012129778A1

WO2012129778A1 - Power output system

Info

Publication number: WO2012129778A1
Application number: PCT/CN2011/072274
Authority: WO
Inventors: 闫广川; 匡超
Original assignee: 阿特斯(中国)投资有限公司
Priority date: 2011-03-29
Filing date: 2011-03-29
Publication date: 2012-10-04

Abstract

A power output system for outputting power to a load (10) includes: an energy storage device (30), for storing electric energy and outputting the electric energy to the load (10); and a control assembly (20), connected with the energy storage device (30) to control the power outputted from the energy storage device (30) to the load (10). The control assembly (20) includes a control device (21) which is used for detecting the remaining capacity of the energy storage device (30) and decreasing the power consumption of the load (10) when the remaining capacity of the energy storage device (30) is lower than a preset threshold. The system can effectively save the power of the energy storage device (30) and thus prolong the operation time of the load (10).

Description

Power output system

[Technical Field]

The present invention relates to a power output system, and more particularly to a technique for controlling output power in a photovoltaic power generation system.

【Background technique】

At present, the electrical energy we use is mainly provided by the power generated by a large centralized generator and transmitted over long distance transmission lines. However, some remote areas are sparsely populated, and the power grid cannot be extended in the short term. Therefore, using nearby energy sources (such as solar energy, wind energy, biomass energy, water power, and thermal energy) that exist near these areas can generate electricity efficiently. Solve power problems in the area. Solar-photovoltaic technology can provide a small "solar home system" (SHS, peak power of 20-200W) for single-family homes, as well as a larger village-level system (about 5kW), so this technology can In the short term, as a major technology option, provide basic electricity needs for homes, small businesses and communities in remote areas, such as lighting, broadcasting radios, and broadcasting television.

Photovoltaic power generation technology uses the photovoltaic effect of a semiconductor interface to convert light energy directly into electrical energy. The key component of this technology is photovoltaic cells, which are typically composed of two or more semiconductor sheets, typically silicon, such as single crystal silicon, polycrystalline silicon, amorphous silicon, and the like. When the light is illuminated, current can be generated inside the battery and conducted as a direct current by the metal conductor. The photovoltaic cells are packaged and protected in series to form a large-area photovoltaic cell module. In conjunction with the prior art shown in Figure 1, the photovoltaic system typically includes a photovoltaic cell assembly 91, a controller 92, and a power storage device 93. The power storage device 93 is used as a reserve power source. For example, the photovoltaic module 91 directly supplies power to the load 94 through the controller 92 during the daytime, and at night, the power storage device 93 supplies power to the load 94 through the controller 92.

Usually, when the power storage device supplies power to the load, it can be pre-calculated according to the demand of the load. Discharge time. However, when the weather is not good, such as continuous rainy days, the amount of electricity charged by the power storage device is not enough to replenish the discharged electricity. Thus, after the electricity is discharged according to the expected discharge time, there is no sufficient power in the power storage device. Used for the load. In view of this, it is necessary to effectively control the discharge of the power storage device to prevent the power storage device from being supplied with sufficient reserve power due to excessive discharge.

[Summary of the Invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electric power output system which solves the above problems, which saves the capacity of the electric storage device by controlling the discharge strategy of the electric storage device, thereby extending the load working time.

In order to achieve the above object, an electric power output system for outputting power to a load includes: an electric storage device for storing electric energy and outputting the electric energy to a load; and a control unit connected to the electric storage device Controls the power output from the power storage device to the load. Wherein, the control component includes control means for detecting the remaining power of the power storage device; and reducing the load power consumption when the remaining power of the power storage device is lower than a predetermined threshold.

As a further improvement of the present invention, the control component includes a first resistor divider circuit connected to the power storage device output bus; the control device obtains the voltage information based on the voltage information collected from the first resistor divider circuit The remaining capacity of the electrical device.

As a further improvement of the present invention, the control device reduces the power consumption of the load by maintaining an input voltage applied to the load and reducing the operating current delivered to the load.

As a further improvement of the present invention, the control assembly further includes a second resistor divider circuit for detecting the input voltage.

As a further improvement of the present invention, the control assembly further includes a current detecting circuit for detecting the operating current.

As a further improvement of the present invention, the control component further includes a current control circuit, the current control circuit includes a current limiting switch; the control component further includes a connection between the control device and the current control circuit for driving the limit A pulse width modulation (PWM) drive circuit for switching the flow switch. As a further improvement of the present invention, the control device is further configured to detect an operating current of the load; and drive the current control circuit by adjusting a duty ratio of the pulse signal outputted by the pulse width modulation driving circuit to reduce the operating current of the load to Book a specific value for the threshold.

As a further improvement of the present invention, the predetermined threshold value includes at least two; when the remaining power of the power storage device is lower than the corresponding threshold, the control device reduces the load power consumption to a specific value corresponding to the threshold.

As a further improvement of the present invention, the system further includes a photovoltaic module for absorbing light energy to convert light energy into electrical energy and storing it by the electrical storage device.

Compared with the prior art, the present invention has the advantages that: according to the preset power consumption value of the power storage device, the load power consumption can be correspondingly reduced, and the power consumption of the power storage device can be effectively saved, thereby prolonging the use time of the load.

[Description of the Drawings]

1 is a block diagram showing the working principle of a photovoltaic system in the prior art;

2 is a circuit block diagram of a specific embodiment of the power output system of the present invention; FIG. 3 is a table showing a mapping relationship between the control device and the load current according to different power consumption values in the power output system shown in FIG.

【detailed description】

The present invention will be described in detail below in conjunction with the embodiments shown in the drawings. However, the embodiments are not intended to limit the invention, and the structures, methods, or functional changes made by those skilled in the art in accordance with the embodiments are included in the scope of the present invention.

The power output system of the present invention can be applied alone or in various types of energy conversion power generation systems, such as photovoltaic power generation systems, wind power generation systems, and hydroelectric power generation systems. The power output system of the present invention will be described in detail below in conjunction with a photovoltaic power generation system. The core component of a photovoltaic power generation system is a photovoltaic module, which is used to absorb light energy and convert light energy into electrical energy output, which can Therefore, a large-area battery assembly formed by arranging a plurality of photovoltaic cells (or solar cells) in series and arranging them in a square array. Among them, the photovoltaic cell absorbs light energy, and the accumulation of different charges on both ends of the battery, that is, the "photogenerated voltage", which is the "photovoltaic effect". Under the action of the photovoltaic effect, the two ends of the photovoltaic cell generate an electromotive force, thereby converting the light energy into electrical energy. Photovoltaic cells are generally composed of two or more semiconductor wafers, typically a silicon material such as single crystal silicon, polycrystalline silicon, amorphous silicon, or the like.

2 shows a specific embodiment of the power output system of the present invention. In the present embodiment, the power output system includes a power storage device 30 and a control unit 20. Although the photovoltaic module is not shown in FIG. 2, it will be readily understood by those skilled in the art from FIG. 1 that the photovoltaic module can be used to charge or directly supply power storage device 30 to load 10 via control component 20. The power storage device 30 is used to store the converted electrical energy from the photovoltaic module to provide backup power to the load 10 when the photovoltaic assembly is unable or insufficient to supply power. The power storage device 30 may be a chemical battery such as a lead-acid battery, a lithium battery, or the like, or may be other types of energy storage elements such as a storage capacitor.

The control unit 20 is connected between the load 10 and the power storage device 30 for managing the discharge of the load from the power storage device. The control unit 20 includes a control unit 21, a signal collection circuit, and a current control circuit 23. The control device 21 may be an integrated circuit including a microcontroller (Micro Controller Unit, MCU). As is well known to those skilled in the art, the microcontroller can include a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and a timing. Module, digital to analog conversion module (A/D Converter), and several input/output ports. Of course, the control device 21 can also use other forms of integrated circuits, such as Application Specific Interconnected Circuits (ASICs) or Field-Programmable Gate Arrays (FPGAs).

The signal collecting circuit includes a first resistor divider circuit for collecting the remaining power of the power storage device 30 (a voltage dividing circuit that is connected to the point A on the output bus of the power storage device 30), and a second method for detecting the load operating voltage. Two-resistor voltage divider circuit (divided into the voltage divider circuit at point B on the bus), and for the set A current-sense circuit that loads the operating current (collects the current signal in the main circuit from the point D on the bus through the wire). After the control device 21 collects the voltage drop at point E, the output voltage of the power storage device can be converted according to the resistance values of Ral and Ra2, and the remaining power of the power storage device at this time is further calculated; After the control device 21 collects the voltage drop at point F, the voltage applied across the load 10 can be converted according to the resistance values of Rb1 and Rb2. Control assembly 20 also includes a current control circuit 23 that is primarily used to limit the current in the main circuit. As is well known to those skilled in the art, current control circuit 23 can include a finite current switch (not shown), which is typically an electronic switch such as a relay, transistor, field effect transistor, thyristor, or the like. In this embodiment, the switch is preferably a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). The control component 20 further includes a Pulse Width Modulation (PWM) driving circuit 22 connected between the control device 21 and the current control circuit 23 for driving the electronic switch to be turned on and off, and the control component can adjust the output PWM signal by The duty cycle drives the current control circuit 23 to achieve control of the magnitude of the current in the main circuit.

In operation, the control device 21 obtains the remaining power of the power storage device 30 through the first resistor divider circuit, and calculates the power consumption of the load 10 according to the voltage obtained by the second resistor divider circuit and the current obtained by the current detection circuit (P= U*I), so that the time when the remaining capacity of the electrical storage device 30 is available for the load can be estimated. However, if the expected load usage time is too short to meet the power demand, the control device 21 needs to adopt a corresponding strategy to extend the load usage time until the power demand can be met. For example, the remaining power is not sufficient to meet the lighting needs of the entire night, or because the power storage device is insufficiently charged due to continuous rainy days, it is necessary to save power of the power storage device as much as possible.

In this embodiment, the control device 21 achieves the purpose of extending the load usage time by setting a multi-level power threshold and correspondingly reducing the power consumption of the load step by step. Preferably, in the embodiment, the operating current of the load is limited. Reduce the power consumption of the load. Specifically, the control device 21 detects the input voltage applied to the load through the second resistor divider circuit, and keeps it stable. Then, the current signal collected by the current detecting circuit obtains the operating current of the load at this time and proceeds accordingly. Control. Refer to the mapping relationship between the different power level values and the corresponding operating current specific values as shown in Figure 3. When the remaining amount of power in the power storage device 21 is higher than or equal to the first threshold T1, the control device 21 does not limit the current in the main circuit, that is, the load remains operated at the rated current. When the remaining amount of power in the power storage device falls below the first threshold T1 but is still higher than or equal to the second threshold T2, the control device 21 adjusts the current limiting switch in the current control circuit 23 through the PWM driving circuit 22. , to reduce the load operating current to a specific value corresponding to the second threshold T2, that is, 90% of the rated current, and determine whether the current in the main circuit has been controlled to the target value by the current detecting circuit. Similarly, when the remaining power of the power storage device 21 further falls below the third or fourth threshold T3, Τ4, the control device 21 reduces the operating current of the load to a specific value corresponding to each of the thresholds 、3, Τ4. The value is 75%, 40%.

As can be seen from the above embodiment, the power consumption of the power storage device is reduced according to the preset power consumption threshold, and the power consumption of the power storage device can be effectively saved, thereby prolonging the use time of the load. In other embodiments, the amount of power consumption may be increased or decreased according to requirements; in addition, in addition to reducing the load power consumption by limiting the current, other methods, such as maintaining the operating current of the load, may be stabilized. Adjust the voltage across the load to reduce the power consumption of the load.

It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the present embodiments are to be considered as illustrative and not restrictive, and the scope of the invention is defined by the appended claims All changes in the meaning and scope of equivalent elements are included in the present invention. Any reference signs or brackets in the claims should not be construed as limiting the claim. In addition, although the present specification is described in terms of embodiments, not every embodiment includes only one independent technical solution. The description of the specification is merely for the sake of clarity, and those skilled in the art should implement the specification as a whole. The technical solutions in the examples may also be combined as appropriate to form other embodiments that can be understood by those skilled in the art.

Claims

Rights request

An electric power output system for outputting electric power to a load, characterized in that the system comprises:

a power storage device for storing electrical energy and outputting the electrical energy to the load;

a control unit coupled to the power storage device to control power output by the power storage device to the load, the control component including control device for

Detecting the remaining capacity of the power storage device;

When the remaining capacity of the power storage device is lower than a predetermined threshold, the load power consumption is reduced.

2. The power output system according to claim 1, wherein the control component comprises a first resistor divider circuit connected to the power storage device output bus; the control device is divided according to the first resistor The voltage information collected by the circuit is obtained, and the remaining power of the power storage device is obtained.

3. The power output system of claim 1 wherein said controlling means reducing power consumption of the load comprises maintaining an input voltage applied to the load and reducing an operating current delivered to the load.

4. The power output system of claim 3, wherein the control component further comprises a second resistor divider circuit for detecting the input voltage.

5. The power output system according to claim 3, wherein the control component further comprises a current detecting circuit for detecting the operating current.

6. The power output system of claim 3, wherein the control component further comprises a current control circuit, the current control circuit comprising a current limiting switch; the control component further comprising a connection between the control device and the current control A Pulse Width Modulation (PWM) driving circuit for driving the current limiting switch between the circuits.

7. The power output system according to claim 6, wherein the control device is further configured to

Detect the working current of the load; The current control circuit is driven by adjusting the duty cycle of the pulse signal outputted by the pulse width modulation drive circuit to reduce the operating current of the load to a specific value corresponding to the predetermined threshold.

8. The power output system according to claim 1, wherein the predetermined threshold value includes at least two; when the remaining power of the power storage device is lower than a corresponding threshold, the control device reduces the load power consumption to The specific value corresponding to the threshold.

9. The power output system of claim 1 further comprising a photovoltaic component for absorbing light energy to convert light energy into electrical energy and storing it by said electrical storage device.