JPH03218264A - rectifier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Fields of Application in Industry] The present invention relates to a rectifier, particularly a rectifier using a field effect transistor.

[Conventional technology]

FIG. 7 is a circuit diagram showing a rectifier disclosed in, for example, Japanese Patent Laid-Open No. 55-109174 (hereinafter referred to as conventional example). In FIG. 7, 1 is an AC power supply, 2 is a transformer whose primary side is connected to the AC power supply 1, 19 and 20 are diodes such as silicon diodes whose anode terminals are connected to the secondary side of the transformer 2, and 3. is a choke coil with one end connected to the cathode terminal of each of these diodes 19 and 20, 4 is a smoothing capacitor whose one end is connected to the other end of this choke coil 3, and the other end is connected to the anode terminal of diode 20, and 5 is this smoothing capacitor. capacitor 4
is a load connected in parallel with .

Next, the operation of this conventional example will be explained using FIG. 7. In FIG. 7 of the drawing, the voltage is stepped down or stepped up from an AC power source 1 through a transformer 2, rectified by a diode 19, smoothed by a diode 20, a choke coil 3, and a smoothing capacitor 4, and then a DC voltage is applied to a load 5.

[Problem to be solved by the invention]

As described above, silicon diodes are generally used as conventional rectifiers, and in order to obtain even higher rectification effects, those derived from the switching regulator type are often used. In this case, since conventional silicon diodes have large switching losses due to minority carriers and losses due to forward voltage, fast recovery diodes and Schottky barrier diodes with short carrier lifetimes have been used.

However, the recent development of LSI is moving in the direction of lowering the driving power supply voltage. As the power supply voltage becomes lower, the loss of rectifying elements, which has not been a problem in the past, has come to be seen as a problem from the viewpoint of rectification efficiency.

Most of the loss in this rectifying element is Joule loss during forward operation, and this can be reduced by reducing the so-called forward voltage drop. but,
There are physical limits to the conventionally used fast recovery diodes and Schottky barrier diodes, so there is a limit to how much the forward drop voltage can be reduced.
For example, there have been problems in that it is difficult to achieve a rectification efficiency of 90% or more at an output voltage of 2V.

This invention was made to solve the above-mentioned problems, and aims to obtain a rectifier device that uses an insulated gate field effect transistor as a rectifying element and has a higher rectifying effect with less loss than conventional diodes. purpose.

[Means to solve the problem]

For this reason, the present invention includes an insulated gate field effect transistor having a first electrode, a second electrode, and a gate electrode, and an integrated circuit parasitic between the first electrode and the second electrode and connected in a desired rectification direction. a reverse direction PN junction rectifier; a current detection means connected in series with the integrated reverse direction PN junction rectifier to detect the presence or absence of current; and a gate signal of the gate electrode based on current detection information from the current detection means. The purpose of the present invention is to achieve the above object by a rectifying device comprising a gate driving means for controlling the rectifying device.

[Effect]

The rectifier according to the present invention detects that a current flows through the integrated reverse PN junction rectifier by means of a power supply detection means,
A channel is generated in the insulated gate field effect transistor by the gate driving means, and the forward voltage drop is reduced by the channel.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

Figure 1 is a circuit diagram showing the configuration of a rectifier that is an embodiment of the present invention, Figure 2 is a characteristic diagram showing the operating current-voltage characteristics of an insulated gate field effect transistor and a conventional diode, and Figure 3 is a diagram showing the operating current-voltage characteristics of an insulated gate field effect transistor and a conventional diode. is a circuit diagram showing the configuration of a rectifier in which a conventional diode is added to this embodiment, Figure 4 is a circuit diagram showing the configuration of a rectifier in the case of a flyback transformer, and Figures 5 and 6 are auxiliary windings. FIG. 2 is a circuit diagram showing a possible configuration of a rectifying device when a rectifying device is provided.

In the drawings, the same or equivalent components as those in the conventional example are indicated by the same reference numerals, and some parts will be explained repeatedly.

In FIG. 1, 6 is a first insulated gate field effect transistor, which has a first electrode a, a second electrode b, and a gate electrode C. In FIG. 7 is an integrated reverse PN junction rectifier parasitic between the first electrode a and the second electrode b of the first insulated gate field effect transistor 6 and connected in a desired rectification direction; 8 is this integrated reverse PN junction rectifier; A first current detection circuit 9, which is current detection means A that is connected in series with the junction rectifier 7 and detects the presence or absence of current, receives current detection information from the first current detection circuit 8 and detects the presence or absence of current. A first gate drive circuit, which is a gate drive stage B, applies a gate signal to an insulated gate field effect transistor 6 to control it; 10 is a second insulated gate field effect transistor; 11 is a second insulated gate field effect transistor; The first electrode a and the second electrode of the effect transistor 10
An integrated reverse PN junction rectifier parasitic between the electrodes b and connected in a desired rectification direction; 12 is a current detection means A connected in series with the integrated reverse PN junction rectifier 11 to detect the presence or absence of current; A certain second current detection circuit 13 is a second gate drive circuit 2a which is a gate drive stage B which receives current detection information from the current detection circuit 12 and applies a gate signal to the insulated gate field effect transistor 10 to control it. and 2b
are terminals on the secondary side of the transformer 2, respectively.

Next, the operation of this embodiment will be explained using FIGS. 1 and 2.

In Figure 1 of the drawing, first, transformer 2 is connected to AC power supply 1.
Pressure decreases or increases through Secondary terminal 2 of transformer 2
If the potential of a is higher than the potential of 2b, the integrated reverse PN
The junction rectifying element 11 is in a blocking state, and no current flows through the second current detection circuit 12. Therefore, the second gate drive circuit 13 gives an off signal to the gate C of the second insulated gate field effect transistor 10,
The second insulated gate field effect transistor 10 is in a state where a channel (not shown) has disappeared. At this time, the current flows through the terminal 2a of the transformer 2, the choke coil 3, the smoothing capacitor 4 and the load 5, the integrated reverse PN junction rectifier 7 of the first insulated gate field effect transistor 6, the first current detection circuit 8, It begins to flow through the path at the end 7-2b of the transformer 2. The first current detection circuit 8 detects the flow of current and provides a signal to the first gate drive circuit 9. As a result, the first gate drive circuit 9 applies a bias to the gate electrode C of the first insulated gate field effect transistor 6 to generate a channel (not shown). When a channel is generated, most of the current flows through the channel,
A linear characteristic as shown by the characteristic line 16 in FIG. 2 is obtained, and the voltage drop can be reduced. Incidentally, in FIG. 2, 14 is the characteristic line of the integrated reverse PN junction rectifier of the insulated gate field effect transistor, that is, the parasitic diode, 15 is the characteristic line of the conventional diode, and 16 is the characteristic line when gate biased as described above. This is the current-voltage inverse characteristic line of an insulated gate field effect transistor.

Next, when the potential at the secondary terminal 2a of the transformer 2 becomes lower than the potential at the secondary terminal 2b, no current flows through the first insulated gate field effect transistor 6 and the integrated reverse PN junction rectifier 7, and the The first current detection circuit 8 detects that the current no longer flows, and provides a signal to the first gate drive circuit 9. This signal causes the first gate drive circuit 9 to turn off the gate of the first insulated gate field effect transistor 6 and eliminate the channel.

On the other hand, the energy stored in the choke coil 3 is transferred to the choke coil 3, the smoothing capacitor 4, the load 5, and the second
The current is regenerated through the integrated reverse PN junction rectifier 11 of the insulated gate field effect transistor 10 and the second current detection circuit 12, respectively. The second current detection circuit 12 is
It detects that the current has started flowing and gives a signal to the second gate drive circuit 13. Thereby, the second gate drive circuit 13 drives the second insulated gate field effect transistor 1.
A bias is applied to the gate electrode of 0 to generate a channel. When a channel is generated, most of the current flows through the channel, making it possible to lower the voltage drop.

Therefore, the Joule loss is lower than that of conventional diodes, and the rectification effect is increased.

Next, an example in which a conventional diode is added to this embodiment will be described with reference to FIG.

In FIG. 3, 17 and 18 are Schottky barrier diodes connected in parallel with the first and second insulated gate field effect transistors 6 and 10, respectively. The rest of the configuration is the same as that of the previous embodiment, so a redundant explanation thereof will be omitted.

In FIG. 3 of the drawing, as described above, by connecting the Schottky barrier diodes 17 and 18 in parallel in the same direction as the integrated reverse PN junction rectifiers 7 and 11 of the insulated gate field effect transistors 6 and 10, respectively, When the potentials of terminals 2a and 2b of transformer 2 are reversed, a signal is quickly applied to each gate of insulated gate field effect transistors 6 and 10. Fear is 1
0 As explained in Figure 2 above, integrated reverse PN junction rectifiers have characteristics as shown in characteristic line 14, whereas conventional diodes, such as Schottky pariah diodes and fast recovery diodes, have characteristics as shown in characteristic line 14. 15, the offset voltage is low and the current flows quickly.

Incidentally, although the above embodiment has been described with respect to a forward type rectifier, the present invention can also be applied to other types of rectifiers, such as flyback type, half bridge type, full bridge type, etc. It is.

Among the above-mentioned types of rectifiers, a flyback type rectifier will be briefly explained using FIG. 4.

FIG. 4 is a circuit diagram of the flyhack type rectifier, and reference numerals 1 to 9 in the figure indicate the same or equivalent parts as in each of the embodiments described above. In this flyback type, the power supply for the gate drive circuit 9 can utilize the output terminal voltage. Further, a known auxiliary winding may be provided to create a gate bias power source, and in this case, a rectifier as shown in FIG. 5 or 6 can be obtained. Each of the current detection circuits 8 and 12 is a circuit using, for example, a CT.

In the above embodiment, an n-channel insulated gate field effect transistor has been described, but it goes without saying that the rectifier may also be constructed of a p-channel.

(Effects of the Invention) As explained above, according to the present invention, it is possible to obtain a rectifier device that uses an insulated gate field effect transistor as a rectifier element and has a higher rectifying effect with less loss than a conventional diode. There is.

[Brief Description of the Drawings] Fig. 1 is a circuit diagram showing a rectifier according to an embodiment of the present invention, Fig. 2 is a characteristic diagram showing operating current-voltage characteristics of an insulated gate field effect transistor and a conventional diode, Third
The figure is a circuit diagram showing the configuration of a rectifier in which a conventional 1 2 diode is added to this embodiment, Figure 4 is a circuit diagram showing the configuration of a rectifier in the case of a flyback transformer, and Figures 5 and 6 are FIG. 7 is a circuit diagram showing the configuration of a rectifier that is possible when an auxiliary winding is provided. FIG. 7 is a circuit diagram showing the configuration of a conventional rectifier. A...Current detection means B...Gate drive means 1...AC power supply 2.1...Transformer 3...Choke coil 4... ... Smoothing capacitor 5 ... Load 6 ... First insulated gate field effect transistor 7 ... First integrated reverse PN junction rectifier 8 ...
...First current detection circuit 9 ...First gate drive circuit 11 ...Second integrated reverse PN junction rectifier 1
3 2...Second current detection circuit 3...Second gate drive circuit 4...Characteristics of parasitic diode 5...Characteristics of conventional diode 1 7, 18... Schottky barrier diode 1 9, 20... Conventional diode Note that in the figures, the same reference numerals do not indicate the same or equivalent parts.

Claims (1)

[Claims] An insulated gate field effect transistor having a first electrode, a second electrode, and a gate electrode, an integrated reverse direction parasitic between the first electrode and the second electrode and connected in a desired rectification direction. a PN junction rectifying element; a current detecting means connected in series with the integrated reverse PN junction rectifying element to detect the presence or absence of current; and controlling a gate signal of the gate electrode based on current detection information from the current detecting means. A rectifier comprising: a gate drive means; and a rectifier.