JPH02241367A - Dc power source - Google Patents

Abstract

PURPOSE:To prevent an input rectifying diode of the side having no open-phase state from damaging by providing an open-phase detector in a DC power source which inputs 3-phase AC. CONSTITUTION:If one of input three phases becomes open, an output of a rectifying diode side connected to an open-phase line of an open-phase detector 8 cannot maintain the output of a photocoupler 19 or 20 to be connected at 'L'. Accordingly, an AND circuit 23 is judged to be abnormal, a signal of abnormality is sent to a PWM controller 7 to stop the operation of an inverter 4. If the inverter is stopped, a current flowing to a rectifying diode in which no open-phase state exists becomes a very small value, thereby preventing it from damaging.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a DC power supply device t that receives three-phase AC as input, and when one of the three input phases is in an open-phase state.
Normally, the operation is the same as that of a single-phase input DC power supply. Therefore, it is conceivable that an excessive current will flow through the input rectifier diodes, leading to damage. This invention relates to an open phase detection circuit that aims to prevent this.

[Conventional technology]

Figure 2 shows a conventional circuit. , +11 is a primary power supply that supplies three-phase AC, (2) is a group of diodes that performs three-phase full-wave rectification of AC power supplied from the primary power supply and converts it into DC power, and (3) is a rectifier diode. (4) is an inverter circuit that performs power conversion by switching the power supplied from the energy bank (3) at a high frequency; Rectifying and smoothing circuit that rectifies and smoothes the output of the inverter circuit (4), +61ij load,
(7) In order to stabilize the supply voltage to load (6),
Rectifier and smoothing circuit (detects the output voltage of 51.

P, w, M (Pulse width) that changes the pulse width of the pulse signal supplied to the inverter circuit (4)
hModula-tion) control circuit.

Next, the operation will be explained. In a conventional DC power supply device, the AC power supplied from the primary power source fil is converted into high current power by a group of rectifier diodes (21), and then the inverter circuit (4) performs high frequency switching to convert the power. , rectification and smoothing circuit (51) rectifies and smoothes and supplies DC power to the load. At this time, the output voltage is stabilized by P, W
, M is performed by changing the pulse width of the pulse signal supplied from the control circuit (7) to the inverter circuit (41).

Here, FIG. 3 is a diagram showing the rectified waveform and input current waveform of a conventional DC power supply, and the thick solid line waveform in FIG. 3 (7) is the voltage waveform of the energy bank (31). The broken line is an image waveform indicating three-phase full-wave rectification.Also, Fig. 3(a) corresponds to the waveform in Fig. 3(7), and the following:
It is a figure which shows the output current waveform of a rectifier diode group (cloudy).

In the DC power supply device configured as described above.

For example, if one of the three input wires is in a so-called open phase state due to disconnection, etc., the remaining two wires will be used.

Power continues to be supplied.

At this time, the input rectifier diode group (2) performs single-phase full-wave rectification operation, resulting in the operation waveform shown in the latter half of the waveform diagram in (7) B) of FIG. In other words, a much larger current flows through the diodes in locations that are not in an open phase state than when they are operating normally, resulting in damage.

[Problem to be solved by the invention]

Conventional DC power supplies are configured with one or more input phases, so if one of the three input phases is open, an excessive current will flow through the diodes that are not in the open phase state, resulting in damage to the diodes. There was a problem with this.

This invention was made in the ninth attempt to solve the above-mentioned problems, and aims to provide a highly reliable device in which the input rectifier diode is not damaged even in an open-phase condition 11.

[Means to solve the problem]

The DC power supply device according to the present invention is provided with an open-phase detection circuit, since when the input is in an open-phase state, an excessive current may flow through the rectifier diodes that are not in the open-phase state, and the diodes may be damaged. When an open phase occurs, the operation of the DC power supply is stopped to prevent damage to the diode.

[Effect]

1. The DC power supply device according to the present invention detects an open phase state (by using an input phase open detection circuit).

This prevents the input rectifier diode from being damaged by excessive current.

〔Example〕

FIG. 1 shows one embodiment of the present invention with jQ, +11~(
7) is the same as - or equivalent to the conventional circuit, fi, +81 is,
Detects input phase loss and activates P, W, M control circuit (7
), (91 to αG are 1
The diode αηa3 that rectifies the AC power supplied from the next power source (1) is a resistor 11912 that limits the current flowing to the photodiode of the photocoupler 11g■.
[1 is to insulate the signal blocked by the diode (9) to 11eK.

The photocoupler 0 for transmitting to the P, W, M control circuit (7) takes the AND of the output of the photocoupler f211, ■, and if none of the inputs are "L".

This is an AND circuit that notifies the P, W, and M control circuits of abnormalities.

The DC power supply configured as described above operates exactly the same as a conventional DC power supply when input power is normally supplied, supplying stable DC power to the load (61). .

In addition, in the open phase detection circuit (8), when power is normally supplied, the outputs of the two rectifier circuits composed of diodes f9) to (IF3) are also output from the photocoupler +1!
A current sufficient to keep the phototransistor I■ in the on state continues to flow through the photodiode. Therefore,
AND circuit oH is judged to be “normal” and P, W, M control circuit (
7), it continues to send a signal indicating that it is "normal".

Here, when one of the three input phases is in an open phase state, the output from the rectifier diode side connected to the line with the open phase in the open phase detection circuit (81) is as follows.

The output of the photocoupler +190R■ to which it is connected cannot be maintained at 1L''. Therefore, the AND circuit is
It is judged as “abnormal” and sent to P, W, M control circuit (7) as “abnormal”.
A signal is sent to stop the operation of the inverter circuit (4). Once the inverter circuit has stopped, the current flowing through the rectifier diodes that are not in an open-phase state becomes a very small value, making it possible to prevent damage.

In addition, in the said Example, in an open phase detection port path (8).

Although an AND circuit 23 is used, it goes without saying that an OR circuit can also be used to provide the same function due to the logical configuration.

〔Effect of the invention〕

This invention has the effect of preventing damage to the input rectifier diode that is not in the open phase state by providing the open phase detection circuit as described above.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a circuit of a DC power supply device to which the present invention is applied, and FIG. 2 is a diagram showing an example of a conventional circuit. FIGS. 3(7) and 3(a) are diagrams showing the operation of the conventional circuit. In the figure, fil is the primary power supply, (2) is the rectifier diode group, (
3I is an energy bank, (4) is an inverter circuit, (
5) is a rectifier and smoothing circuit, (61 is a load, (7) is P, W,
M control circuit. (8) is an open phase detection circuit, (91 to αe are diodes, a
ηαse! n is a resistor, α9I21 is a photocoupler,
0 is an AND circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] a rectifier diode group that converts three-phase AC power supplied from the outside into direct current; an energy bank including an output of the rectifier diode group; and an inverter circuit that converts the power supplied from the energy bank into power at a high frequency;
A rectifying and smoothing circuit for rectifying and smoothing the output of the inverter circuit, and a P.C. W. M (Pulse Widt
h Modulat-ion) control circuit and the three-phase AC power supply, and if a phase loss occurs, P. W. It has the function of sending an abnormal signal to the M control circuit, and
A DC power supply device comprising an open-phase detection circuit configured with a photocoupler or the like.