Battery replacement device for electric tool

Abstract

An electric tool battery replacement device is characterized by comprising an alternating current-direct current conversion box (1), a voltage reduction box (2), an alternating current input line (3) and a high-voltage direct current transmission line (4), the alternating current input line (3) is connected to the input end of the alternating current-direct current conversion box (1) so as to be connected with an alternating current power supply, the high-voltage direct current transmission line (4) is connected between the output end of the alternating current-direct current conversion box (1) and the input end (2) of the step-down box (2), and the output end of the step-down box (2) is connected with an electric tool (5); a rectifying circuit is arranged in the alternating current-direct current conversion box (1) and is used for rectifying alternating current into direct current; and a direct-current voltage reducing and stabilizing circuit is arranged in the voltage reducing box (2) and is used for reducing high-voltage direct current into low-voltage direct current and outputting the low-voltage direct current in a voltage stabilizing manner. According to the utility model, rectification boost and DC voltage reduction output are completed in two parts (i.e., the AC-DC conversion box and the voltage reduction box), and a high-voltage DC power transmission principle is adopted, so that the loss caused by a line is reduced, and the utilization rate of energy is improved.

Description

Technical Field

[0001] The utility model relates to the field of power tools, and particularly relates to a battery replacement device for power tools. Background Art

[0002] In recent years, battery-powered power tools have been increasingly widely used due to their portability. These tools are basically powered by battery packs. However, the capacity of the battery pack is limited. For some high-power and extra-high-power tools, the battery discharge time is short, and it needs to be charged after a few minutes of use, which directly affects the working efficiency of long-term and fixed-site work. At present, a DC power supply can be used instead of the battery, but the traditional DC power supply on the market is large in volume and heavy in weight. If a lead wire is directly led out at the output end with a conversion socket to supply power to the tool, due to the long lead wire, low voltage, and large current, the wire loss is large and it generates heat. If the output wire is shortened and the input wire is lengthened, it is inconvenient for the tool to work with a large power supply. Summary of the Invention

[0003] The purpose of the utility model is to provide a battery replacement device for power tools, which solves the problem of long-term continuous operation of existing cordless tools, and also overcomes the problems of line loss caused by low-voltage and large-current transmission and the high cost of too thick wires when using traditional DC power supplies at present.

[0004] The AC-DC conversion box and the step-down box are connected by a high-voltage DC transmission line (that is, high-voltage DC is transmitted).

[0005] To achieve the above purpose, the technical solution adopted by the utility model is: a battery replacement device for power tools, including an AC-DC conversion box, a step-down box, an AC input line, and a high-voltage DC transmission line; the AC input line is connected to the input end of the AC-DC conversion box for connecting an AC power supply, the high-voltage DC transmission line is connected between the output end of the AC-DC conversion box and the input end of the step-down box, and the output end of the step-down box is for connecting a power tool; a rectification circuit is arranged in the AC-DC conversion box for rectifying AC into DC; a DC step-down and voltage stabilization circuit is arranged in the step-down box for stepping down high-voltage DC into low-voltage DC and outputting it with voltage stabilization.

[0006] In the above solution, a thermistor is connected to the input end of the rectification circuit of the AC-DC conversion box, and a capacitor charging current-limiting resistor short-circuit circuit is also arranged in the AC-DC conversion box to short-circuit the thermistor after the capacitor is charged when the power is turned on through the capacitor charging current-limiting resistor short-circuit circuit.

[0007] In the above solution, a heat dissipation fan and a first isolated power supply for supplying power to the heat dissipation fan are arranged in the AC-DC conversion box.

[0008] In the above solution, the DC step-down and voltage stabilization circuit in the step-down box is composed of a DC-DC step-down circuit, a digital synchronous rectification circuit, and a second isolated power supply circuit. Further, the digital synchronous rectification circuit adopts gallium nitride parallel technology, and its output stage is connected in parallel with multiple high-frequency and low-resistance capacitors to reduce the overall power supply ripple.

[0009] In the above solution, a power factor correction circuit is also provided in the AC-DC conversion box.

[0010] The utility model is designed as a separate and independent AC-DC conversion box and step-down box. The AC-DC conversion box can be placed at the power supply end, and the step-down box can be placed at the electric tool end. The AC-DC conversion box converts the AC high voltage (such as AC 120 V - 240V) into a high-voltage DC voltage through rectification and transformation technology, and then transmits it to the step-down box through a high-voltage DC transmission line (that is, transmitted by high-voltage DC) to step down to the low-voltage DC suitable for the electric tool and supply it to the electric tool.

[0011] The beneficial effects of the utility model: The electric tool battery replacement device provided by the utility model divides the rectification boost and DC step-down output into two components (i.e., the AC-DC conversion box and the step-down box) to improve the convenience of using the electric tool. A high-voltage DC transmission line is set in the middle for transmission. Using the principle of high-voltage DC power transmission, the loss caused by the line is reduced, and the energy utilization rate is improved; moreover, the AC-DC conversion box can be placed at the power supply end, and the step-down box can be placed at the electric tool end. The step-down box is basically similar in size to the battery pack and will not increase the load of the electric tool. Description of the Drawings

[0012] Figure 1 is the schematic diagram of the principle structure of the utility model;

[0013] Figure 2 is the external shape schematic diagram when the utility model is in use;

[0014] Figure 3 is the schematic diagram of the capacitor charging current limiting resistor short-circuit circuit of the utility model;

[0015] Figure 4 is the schematic diagram of the DC-DC step-down circuit of the utility model;

[0016] Figure 5 is the schematic diagram of the digital synchronous rectification circuit of the utility model.

[0017] In the above figures: 1. AC-DC conversion box; 2. Step-down box; 3. AC input line; 4. High-voltage DC transmission line; 5. Electric tool. Detailed Embodiments

[0018] The following further describes the utility model in conjunction with the drawings and embodiments:

[0019] Embodiment: Refer to Figures 1-5 as shown, an electric tool battery replacement device:

[0020] This electric tool battery replacement device includes an AC-DC conversion box 1, a step-down box 2, an AC input line 3, and a high-voltage DC transmission line 4.

[0021] The AC input line 3 is connected to the input end of the AC-DC conversion box 1 for connecting to an AC power supply. The high-voltage DC transmission line 4 is connected between the output end of the AC-DC conversion box 1 and the input end of the step-down box. The output end of the step-down box 2 is for connecting to an electric tool 5, such as Figure 1 and Figure 2 .

[0022] A rectification circuit and a power factor correction circuit are provided inside the AC-DC conversion box 1 for rectifying AC into DC. A DC step-down and voltage stabilization circuit is provided inside the step-down box 2 for stepping down high-voltage DC to low-voltage DC and outputting it with voltage stabilization.

[0023] Specifically, a thermistor is connected to the input end of the rectification circuit of the AC-DC conversion box 1. A capacitor charging current-limiting resistor short-circuit circuit is also provided inside the AC-DC conversion box to short-circuit the thermistor after the capacitor charging is completed when the power is turned on. There is a large capacitor for filtering after rectification in the rectification circuit. To ensure that there is no sparking phenomenon when the power is turned on instantaneously (during the process of inserting the plug into the power socket), a thermistor is connected in series at the input end of the rectification circuit. However, if the thermistor is always connected in the circuit and in a working state, it will generate a large amount of heat and affect the power efficiency. Therefore, a capacitor charging current-limiting resistor short-circuit circuit is specifically added to short-circuit the thermistor after the capacitor charging is completed when the power is turned on. In this way, both the plug does not spark and the overall performance and efficiency are not affected. The overall circuit works more reliably. The specific capacitor charging current-limiting resistor short-circuit circuit is as Figure 3 shown.

[0024] The AC-DC conversion box 1 is composed of a cooling fan and a first isolated power supply for powering the cooling fan.

[0025] The DC step-down and voltage stabilization circuit inside the step-down box 2 is composed of a DC-DC step-down circuit, a digital synchronous rectification circuit, and a second isolated power supply circuit. The specific DC-DC step-down circuit is as Figure 4 shown, and the digital synchronous rectification circuit is as Figure 5 shown. In particular, the digital synchronous rectification circuit adopts a gallium nitride parallel technology to increase the switching frequency to 100K, improve the overall load efficiency and performance, and parallel multiple high-frequency low-resistance capacitors at the output stage to reduce the overall power supply ripple.

[0026] Since the first isolated power supply is provided in the AC-DC conversion box 1 and the second isolated power supply circuit is provided in the step-down box 2, the AC-DC conversion box 1 and the step-down box 2 are powered separately, which reduces the number of lines of the high-voltage DC transmission line 4 between the AC-DC conversion box 1 and the step-down box 2, further controls the cost, and improves the reliability of the product.

[0027] From Figure 2 , we can see that the high-voltage DC transmission line 4 can be set very long, and the step-down box 2 can move freely with the power tool 5 and directly supply power to the existing power tool 5. In this way, the power tool 5 can be used for a long time, improving the practicability of the power tool 5 and solving the problem of long-term continuous operation of existing cordless tools. Moreover, the present utility model first converts alternating current into direct current and transmits high-voltage direct current without step-down (for example, above 300V DC). In this way, the circuit loss in the high-voltage DC transmission line 4 is relatively small, and the requirements for the wire are reduced. In the prior art, in order to reduce the circuit loss, the wire is made as thick as possible, which will increase the cost of the wire. Therefore, in this embodiment, the rectification and boost of the AC-DC conversion box 1 and the step-down and filtering of the step-down box 2 are separated, which can reduce the transmission loss. Terminals are provided on the step-down box 2 to directly plug into the power tool 5, and it can be adapted to the tool socket sizes and communication matching of different manufacturers according to requirements, making the use more flexible.

[0028] The above embodiments are only for explaining the technical concept and features of the present utility model, and the purpose is to enable those familiar with this technology to understand the content of the present utility model and implement it accordingly. It should not be used to limit the protection scope of the present utility model. All equivalent changes or modifications made according to the spirit of the present utility model should be covered within the protection scope of the present utility model.

Claims

1. A battery replacement device for electric tools, characterized in that: It comprises an AC / DC conversion box (1), a step-down box (2), an AC input line (3) and a high-voltage DC transmission line (4); the AC input line (3) is connected to the input end of the AC / DC conversion box (1) to supply an AC power source, the high-voltage DC transmission line (4) is connected between the output end of the AC / DC conversion box (1) and the input end of the step-down box, and the output end of the step-down box (2) is connected to an electric tool (5); The AC / DC conversion box (1) is provided with a rectifier circuit for rectifying AC into DC; the step-down box (2) is provided with a DC step-down and voltage stabilizing circuit for stepping down high-voltage DC into low-voltage DC and outputting it in a regulated voltage.

2. The power tool battery replacement device according to claim 1, characterized in that: A thermistor is connected to the input end of the rectifier circuit of the AC / DC conversion box (1), and a capacitor charging current limiting resistor short-circuit circuit is also provided in the AC / DC conversion box, so that the thermistor is short-circuited after the power supply is turned on and the capacitor is charged.

3. The power tool battery replacement device according to claim 1, characterized in that: The AC / DC conversion box (1) is provided with a cooling fan and a first isolated power supply for supplying power to the cooling fan.

4. The power tool battery replacement device according to claim 1, characterized in that: The DC step-down and voltage stabilization circuit in the step-down box (2) is composed of a DC-DC step-down circuit, a digital synchronous rectification circuit and a second isolated power supply circuit.

5. The power tool battery replacement device according to claim 4, characterized in that: The digital synchronous rectification circuit adopts gallium nitride parallel connection technology, and its output stage is connected in parallel with multiple stages of high-frequency low-resistance capacitors to reduce the overall ripple of the power supply.

6. The power tool battery replacement device according to claim 1, characterized in that: A power factor correction circuit is also provided in the AC / DC conversion box (1).

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