CN201490909U

CN201490909U - Rectifying circuit of low-energy consumption field-effect tube

Info

Publication number: CN201490909U
Application number: CN2009200625110U
Authority: CN
Inventors: 刘开展
Original assignee: XIAMEN FANGGUANG ELECTRONIC TECHNOLOGY Co Ltd
Current assignee: XIAMEN FANGGUANG ELECTRONIC TECHNOLOGY Co Ltd
Priority date: 2009-08-18
Filing date: 2009-08-18
Publication date: 2010-05-26
Anticipated expiration: 2019-08-18

Abstract

The utility model discloses a rectifying circuit of a low-energy consumption field-effect tube, which comprises an oppositely connected field-effect tube and a drive control circuit thereof. The rectifying circuit is suitable for the rectifying circuit with large electric current, overcomes the defects of the large consumption, the large heating quantity, and the large volume of a heat-dissipating plate when rectifying with a diode in the prior art, and adopts the field-effect tube to realize alternating-current rectifying with less consumption and low heating quantity, and reduces the volume of a product. The utility model further discloses a rectifying circuit of a low-energy consumption field-effect tube with a P-shaped field-effect tube, wherein the structure thereof is opposite to that of the former one, the diode is positively connected between the source electrode and the drain electrode of the field-effect tube, and one end of a filter capacitor is connected with the drain electrode of the field-effect tube.

Description

Low energy consumption field effect transistor rectification circuit

Technical field

The utility model relates to a kind of AC rectification technology, refers to the commutation technique of Switching Power Supply especially, is specially adapted to the high efficiency rectification of low-voltage, big electric current.

Background technology

Present various rectification circuits all are constituted by a diode, and diode is a passive component, and it has, and cost is low, the simple advantage of circuit, in the rectification circuit of high voltage, very high rectification efficiency is arranged also, is subjected to everybody liking deeply, and is widely used.Its weak point is, the rectifier loss of diode occurs with relatively-stationary pressure drop form, in high-frequency rectification circuit, minimum rectifier loss also has about 0.5V, this power consumption in the rectification circuit of big electric current is very big, rectifying tube need dispose very big heating panel, causes overall volume increase, poor heat stability.For example, its rectifier loss of the power supply of 5V can reach 9-15%, the power supply of 5V 200W, and rectifier loss reaches 18-30W.If its rectification pressure drop can be dropped to 0.1V, then its rectifier loss will be reduced to 4-8W.If the rectification pressure drop is 0.05V, then rectifier loss has only 2-4W, so only needs very little fin, or several pipe parallel connections, and radiation fin can not yet.So, the temperature rise of power supply reduces greatly, and the volume of power supply reduces greatly.

The field effect transistor forward resistance is little, can make forward conduction voltage drop＜0.1V, but high-power FET all is connected to the reverse protection diode, and promptly reverse voltage has only 0.6V.Thereby field effect transistor can not realize AC rectification with conventional connection.

The utility model content

Main purpose of the present utility model, be to provide a kind of low energy consumption field effect transistor rectification circuit, it is applicable to the rectification circuit of big electric current, rectifier loss is big when replacing the available technology adopting diode rectification, caloric value big, need the bulky deficiency of heating panel, break the normal procedure and adopt field effect transistor to realize AC rectification, rectifier loss is little, and caloric value is low, reduces small product size.

In order to reach above-mentioned purpose, solution of the present utility model is:

A kind of low energy consumption field effect transistor rectification circuit comprises the field effect transistor of a reversal connection and its Drive and Control Circuit.

Above-mentioned field effect transistor is a N type field effect transistor, described rectification circuit also comprises a diode and a filter capacitor, diode forward is connected between the drain electrode and source electrode of field effect transistor, one end of filter capacitor is connected with the source electrode of this field effect transistor, the drain electrode of this field effect transistor and the other end of filter capacitor are the rectification ac input end, and the two ends of filter capacitor are the rectification ac output end.

Above-mentioned field effect transistor is a P type field effect transistor, described rectification circuit also comprises a diode and a filter capacitor, diode forward is connected between the source electrode and drain electrode of field effect transistor, one end of filter capacitor is connected with the drain electrode of this field effect transistor, the source electrode of this field effect transistor and the other end of filter capacitor are the rectification ac input end, and the two ends of filter capacitor are the rectification ac output end.

After adopting such scheme, the utility model uses this active element of field effect transistor to carry out AC rectification, utilize its special operating characteristic, to drain and oppositely be connected with source electrode, when the conducting of field effect pipe, current direction when the sense of current of DS uses with routine is opposite, realizes the high efficiency rectification thus.Though field effect transistor is an active element, unit price is more expensive than diode, but also to dispose the corresponding driving control circuit, the element cost increases a lot, but because its rectifier loss is little, therefore only need very little fin, even do not use fin passable yet, and need not to lay in the traditional structure used circuit boards such as diode, parts such as shell, save cost, it is few that power supply concentration total cost is increased, thereby, low for output voltage, power is big, volume is little, the Switching Power Supply that performance requirement is high uses field effect transistor than diode incomparable advantage to be arranged.

Description of drawings

Fig. 1 is circuit theory diagrams of the present utility model.

Embodiment

Below in conjunction with drawings and the specific embodiments operation principle of the present utility model and syndeton are elaborated.

With reference to shown in Figure 1, it is the johning knot composition of the utility model low energy consumption field effect transistor rectification circuit, it comprises the field effect transistor 1 of reversal connection and the Drive and Control Circuit 1 that is mated, particularly, also comprise diode D1 and filter capacitor C1, and this embodiment is to be that example describes with N type field effect transistor, uses the syndeton of P type field effect transistor just the opposite therewith, does not repeat them here.

Drive and Control Circuit 1 comprises auxiliary circuits such as the phase-detection that is equipped with field effect transistor Q1, driving, control.Guarantee that field effect transistor Q1 is in correct break-make rectification state, this is a conventional structure, only with the block diagram schematic representation, and provides power supply by power input V2 for Drive and Control Circuit 1 among the figure, by the grid G of drive controlling output V3 connection field effect transistor Q1, also has the phase place of interchange input V1.

Diode D1 forward is connected between the drain D and source S of field effect transistor Q1, the end of filter capacitor C1 is connected with the source S of field effect transistor Q1 (being the B place among Fig. 1), the other end (being the C place among Fig. 1) of the drain D of this field effect transistor Q1 (being the A place among Fig. 1) and filter capacitor C1 is the rectification ac input end, and the two ends of filter capacitor C1 (B, C) is the rectification ac output end.

Please refer to shown in Figure 1 again, rectify when the interchange for the treatment of rectification is input as A, when the C end is negative, V1 obtains high potential (potential reference point is " A "), and V3 exports high level, and promptly the current potential at V3 place exceeds about the 10V of A place, field effect transistor Q1 conducting this moment, be equivalent to diode D1 forward conduction, because its pressure drop is very little, conduction loss is very little, so its rectification efficiency is very high, electric current flows to B from A and charges to filter capacitor C1; And when the voltage of input be the positive A of C when negative, V1 becomes electronegative potential, the V3 output low level, field effect transistor Q1 enters by off state, its leakage current that oppositely ends is very little, its loss can be ignored; Circulation obtains the negative direct voltage of the positive C of B repeatedly thus, can realize the purpose that replaces diode to carry out the high efficiency rectification with field effect transistor Q.

Because the electric current that flows through when the internal resistance of field effect transistor and rectification when conducting is depended in the rectification pressure drop of field effect transistor Q1, and the conducting resistance of field effect transistor Q1 is more little, and rectifier loss is just more little, therefore can be according to different user demands, select the field effect transistor Q1 of suitable model for use, enlarged the scope of application.

In sum, the utility model has been used four key properties of field effect transistor neatly, and the one, conducting resistance is little, and the 2nd, conducting resistance presents the pure resistance characteristic, but two-way admittance, the 3rd, switching speed is fast, and the 4th, the DS end also is connected to backward diode.One of above-mentioned characteristic shows that field effect transistor has had the basis of high efficiency rectification; But the DS electric current that two of characteristic shows field effect transistor is reverse flow also; Three of characteristic shows that field effect transistor can be used for high-frequency rectification; Four explanation field effect transistor of characteristic could realize the purpose of rectification in the time of must oppositely using.Because the inside of field effect transistor Q1 also is connected to backward diode D1, forward is equivalent to the reverse withstand voltage only 0.6V of rectifying tube when using, can not oppositely end, thereby do not reach rectification effect, the utility model extremely oppositely uses the DS of field effect transistor Q1, and problem has just solved, one, the conducting resistance of forward is constant, has possessed the condition of the ultra-low loss of forward conduction; Its two, internal body diodes has become " forward " parallel connection, but also the double as auxiliary rectifier is used; Its three, the field effect transistor rectification by the time reverse withstand voltagely become former field effect transistor maximum operating voltage.Thereby having possessed the essential condition of high this rectification of the little and reverse cut-ff voltage of forward conduction resistance, this ingenious part of the present utility model just is that field effect transistor can be made the key that rectifying tube uses, and is core of the present utility model.

Above embodiment only is explanation technological thought of the present utility model; can not limit protection range of the present utility model with this; every according to the technological thought that the utility model proposes, any change of being done on the technical scheme basis all falls within the utility model protection range.

Claims

1. a low energy consumption field effect transistor rectification circuit is characterized in that: field effect transistor and its Drive and Control Circuit of comprising a reversal connection.

2. low energy consumption field effect transistor rectification circuit as claimed in claim 1, it is characterized in that: described field effect transistor is a N type field effect transistor, described rectification circuit also comprises a diode and a filter capacitor, diode forward is connected between the drain electrode and source electrode of field effect transistor, one end of filter capacitor is connected with the source electrode of this field effect transistor, the drain electrode of this field effect transistor and the other end of filter capacitor are the rectification ac input end, and the two ends of filter capacitor are the rectification ac output end.

3. low energy consumption field effect transistor rectification circuit as claimed in claim 1, it is characterized in that: described field effect transistor is a P type field effect transistor, described rectification circuit also comprises a diode and a filter capacitor, diode forward is connected between the source electrode and drain electrode of field effect transistor, one end of filter capacitor is connected with the drain electrode of this field effect transistor, the source electrode of this field effect transistor and the other end of filter capacitor are the rectification ac input end, and the two ends of filter capacitor are the rectification ac output end.