EMI suppression circuit in AC high-voltage brushless tool

Abstract

The utility model discloses an EMI suppression circuit in an AC high voltage brushless tool, which comprises a resistor R3, two capacitors Y2 and a rectifier bridge BD, the number of the capacitors Y2 is two, the two capacitors Y2 are connected in series, the resistor R3 and the capacitors Y2 are connected in series, and the output end of the rectifier bridge BD is connected with the two capacitors Y2. According to the utility model, the power supply rectification and filter circuit is used for converting alternating current into direct current, filtering the direct current through a capacitor and finally supplying power to the motor; due to the directivity of the rectifier bridge BD, the current can only flow to the motor from DC + and cannot flow reversely; the negative influence of the counter electromotive force generated by the motor on the power supply can be prevented, and the power supply can be protected from the influence of the voltage peak; the resistor R3 may be used to limit the current flowing through the rectifier bridge BD to ensure that it does not exceed a safe operating range.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of suppression circuit, specifically is a kind of EMI's suppression circuit in AC high voltage brushless tool. BACKGROUND

[0002] At present, the conventional electromagnetic compatibility suppression means mainly relies on bus filter with power inductance and capacitance as main body, which can suppress electromagnetic interference emission to a certain extent, but the cost is high and the occupied volume is large, and the filter position is far away from the interference source, so the suppression effect of electromagnetic interference is limited. In recent years, with the rapid development of society and the warming up of export to Europe, there is an increasingly strict EMI suppression demand for electronic and electrical products. The EMI suppression method of DC brushless motor mainly reduces the space radiation emission by limiting the switching speed of power MOS and adding common mode choke coil in the energy loop.

[0003] The existing patent No. CN220653136U discloses a three-phase brushless motor electromagnetic interference suppression circuit, belonging to the field of brushless motor EMI suppression, comprising a basic drive circuit and a resistance-capacitance filter network. The basic drive circuit includes a three-phase bridge drive circuit, a sampling resistor and a three-phase brushless motor M1. The resistance-capacitance filter network includes a filter capacitor and a filter resistor. The utility model utilizes the filter network composed of filter capacitor and filter resistor to establish the filter network between phase line, GND and PE, realizing the filtering of electromagnetic interference of the drive circuit. Compared with the traditional bus filter circuit with power inductance and capacitance as main body, the utility model directly implements resistance-capacitance filtering on the motor phase line, which is closer to the noise source and has better filtering effect. Meanwhile, the utility model innovatively establishes a resistance-capacitance filter network combining GND and PE two discharge paths, which has better filtering effect on electromagnetic interference and can effectively suppress three-phase brushless motor electromagnetic interference.

[0004] The existing suppression circuit can achieve certain suppression effect, but the suppression effect is relatively poor. Therefore, we propose a kind of EMI's suppression circuit in AC high voltage brushless tool. UTILITY MODEL CONTENTS

[0005] The utility model aims to provide a kind of EMI's suppression circuit in AC high voltage brushless tool, to solve the problems in prior art.

[0006] To achieve the above-mentioned purpose, the utility model provides the following technical scheme: a kind of EMI's suppression circuit in AC high voltage brushless tool, including resistance R3, capacitor Y2 and rectifier bridge BD, the capacitor Y2 is provided with two, and two the capacitor Y2 is mutually connected in series, the resistance R3 and capacitor Y2 are connected in series, and the output end of the rectifier bridge BD is connected with two capacitors Y2.

[0007] Preferably, the four diodes of the rectifier bridge BD are connected to the four terminals, respectively, and two diodes of the rectifier bridge BD are connected to the live wire and the ground wire, respectively.

[0008] Preferably, the motor is further included, and the positive pole of the motor is connected to DC+, and the negative pole of the motor is connected to DC-.

[0009] Preferably, the casing is further included, and the casing is connected to the ground wire through the resistor R3.

[0010] Compared with the prior art, the power supply rectification and filtering circuit has the beneficial effects that:

[0011] 1. The power supply rectification and filtering circuit is used for converting alternating current into direct current and filtering through a capacitor, and finally supplying power to the motor.

[0012] 2. Due to the directionality of the rectifier bridge BD, the current can only flow from DC+ to the motor, and cannot flow reversely; the back electromotive force generated by the motor can be prevented from having a negative impact on the power supply, and the power supply can be protected from voltage spikes; and the resistor R3 can be used for limiting the current flowing through the rectifier bridge BD, so as to ensure that the current will not exceed the safe working range. BRIEF DESCRIPTION OF DRAWINGS

[0013] The accompanying drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and serve to explain the present application, and do not constitute a limitation on the present application. In the drawings:

[0014] Figure 1 is a circuit diagram of the present application. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application.

[0016] Please refer to Figure 1The utility model discloses an AC high -voltage brushless tool EMI's suppression circuit, including resistance R3, capacitor Y2 and rectifier bridge BD, two are provided with to capacitor Y2, and two capacitor Y2 are mutually connected in series, resistance R3 and capacitor Y2 are connected in series, the output of rectifier bridge BD is connected with two capacitors Y2.When the power is on, the current will flow through rectifier bridge BD and enter motor. Due to the directionality of rectifier bridge BD, current can only flow from DC+ to motor, and cannot flow reversely. This can prevent the counter electromotive force generated by motor from having negative influence on power supply, and help to protect power supply from voltage spike. Resistance R3 can be used to limit the current flowing through rectifier bridge BD, to ensure that it will not exceed the safe working range.

[0017] Preferably, the four diodes of the rectifier bridge BD are connected to four endpoints respectively, and two diodes of the rectifier bridge BD are connected to the live wire and the ground wire respectively; the rectifier bridge BD is composed of four diodes, for converting AC into DC; the output end of the rectifier bridge BD is marked with "DC+" and "DC-", indicating the positive and negative poles of DC.

[0018] Preferably, the motor is further included, the positive pole of the motor is connected to DC+, and the negative pole of the motor is connected to DC-.

[0019] Preferably, the casing is further included, and the casing is connected to the ground wire through resistance R3.

[0020] The working principle of the utility model is as follows: the power rectification and filtering circuit is used for converting AC into DC, and filtering through capacitor, finally supplying power to the motor.

[0021] Finally, it should be pointed out that: the above-mentioned is only the preferred embodiment of the utility model, and is not used for limiting the utility model, although the utility model has been described in detail with reference to the foregoing embodiments, for the person skilled in the art, it still can modify the technical scheme recorded in the foregoing each embodiment, or equivalent replacement to part of technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model, should be included in the protection scope of the utility model.

Claims

1. An EMI suppression circuit for an AC high voltage brushless tool, comprising: It comprises resistance R3, capacitor Y2 and rectifier bridge BD, the capacitor Y2 is provided with two, and the two capacitors Y2 are connected in series, the resistance R3 and the capacitor Y2 are connected in series, and the output end of the rectifier bridge BD is connected with the two capacitors Y2.

2. The EMI suppression circuit for AC high voltage brushless tools according to claim 1, wherein Four diodes of the rectifier bridge BD are connected to four end points respectively, and two diodes of the rectifier bridge BD are connected with the live wire and the ground wire respectively.

3. The EMI suppression circuit for AC high voltage brushless tools of claim 1, wherein, It also comprises a motor, the positive electrode of the motor is connected to DC+, and the negative electrode of the motor is connected to DC-.

4. The EMI suppression circuit for AC high voltage brushless tools according to claim 3, wherein It also comprises a casing, the casing is connected with the ground wire through the resistance R3.

Images