JPH0454839A - Dc power supply - 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] [Industrial Application Field] The present invention is directed to the power M
It is used for gate drives of O3, thyristors, etc., and particularly relates to DC power supplies that require output in a form that is electrically isolated from the power supply circuit.

[Problems to be solved by conventional technology and invention] Part 3
The figure is for example "Nikkei Electronics" 1989.3.6
(No. 468) P. 159 is a circuit diagram showing this kind of conventional DC power supply device. In this case, the AC input (1) is rectified and smoothed by the rectifier port N (2), and the power MO3FETG41 driven by the control IC (3) that operates at high speed generates high-frequency AC power. This AC power is electrically isolated by an isolation transformer and transmitted to a rectifier circuit (6), which converts it into DC power and outputs it as a gate drive DC power source.This output circuit and The signal circuit is isolated from the control IC (3) by a photocoupler (2).

Incidentally, in a power conversion device or the like having a large capacity and high voltage rating, extremely high reliability is required of the gate drive circuit thereof. As a measure to improve this reliability, a method of providing parallel redundancy by providing a plurality of DC power supply devices can be considered.

If you try to adopt this method using a conventional one, you will need to connect multiple DC power supplies in parallel at their output ends, as shown by the broken lines in Figure 3, but in this case,
Since devices each containing a high-voltage isolation transformer (51) are combined, there is a problem in that the entire device becomes large and expensive.

This invention was made to solve the above-mentioned problems, and aims to provide a highly reliable DC power supply device using a single isolation transformer and having parallel redundancy.

[Means and effects for solving the problem] A DC power supply device according to the present invention includes a plurality of AC power supply devices that output AC power in response to an operation command, and each output terminal of which is connected in parallel with another; a rectifier circuit that inputs the input, converts it to a DC output, and outputs it via a smoothing capacitor; an isolation transformer inserted between the AC power supply device and the rectification circuit to electrically insulate the two; and an output terminal of the AC power supply device. It is equipped with a voltage sensor that detects voltage and a predetermined command control circuit, and is configured to cyclically select one of the AC power supplies and sequentially send out the operation commands at a predetermined first time interval. At the same time, if the output of the voltage sensor does not rise even after a predetermined second time interval has elapsed after the elapse of the first time interval, another AC power supply other than the AC power supply selected at that time By selecting and sending the operation command, continuous DC power is output from the rectifier circuit.

〔Example〕

FIG. 1 is a circuit diagram showing a DC power supply device according to an embodiment of the present invention. In FIG. 0, (101) and (+02) are AC power supply devices, two of which are provided here for parallel redundancy. Its component (11) is an AC power supply internal circuit, which is continuously controlled by a signal from an input terminal (12). (13) is an internal transformer, (14) is a control relay, and the signal G input to the control input terminal (15)
1 or G2 is “1”, close the contact, “0”
”, the contact is opened. (16) is an output terminal, and the output terminals (16) of both AC power supply devices (101) and (102) are connected in parallel to each other.

(20) is a voltage sensor that detects the voltage appearing at the output terminal (16), and when a voltage is present, the output terminal (20)
The signal VSO from 1) is "O" and becomes "1" when no voltage is present.

(30) is an isolation transformer whose primary winding is connected to the output terminal (16), whose secondary winding is connected to the rectifier circuit (40), and electrically insulates both circuits.

Note that one end of the primary winding of the isolation transformer (30) is grounded.

The rectifier circuit (40) is composed of a diode bridge (41) and a smoothing capacitor (42), and includes an isolation transformer (
The AC power from 30) is rectified and smoothed to its output terminal (4
3) outputs DC power for gate drive.

(50) is a command control circuit that sends signals G1 and G2 as operation commands to the AC power supply (lot) and (+02>. Its component (51) outputs a clock signal CLK of a predetermined pulse width. The generated oscillator, (5
2) is a buffer that outputs the input signal non-inverted, (53)
is an inverter that inverts the input signal and outputs it, (54)
(55) is a NOR circuit, (56) and (57) are NAND
AND circuit 8) or 62) is an AND circuit, (63)
(64) is a LATCH circuit, (65) is an OR circuit, (
66) (67) is a failure detection relay, (68) is a resistor,
(69) is a capacitor, (70) is an exclusive NOR circuit,
(71) is a NOR circuit, (72) is a one-shot multivibrator (OSM), and (73) and (74) are inverters.

Next, the operation will be explained in detail with reference to the time chart shown in FIG. First, a case where both AC power supply devices (101) and (102) are operating normally will be described. At this time, the LATCH circuit (63) and the LA
The output signals ER1 and ER2 of the TCH circuit (64) are both "0" as described later, and accordingly, the OR circuit (65)
The output signal of is "O". In this state, the oscillator (51) outputs the signal CLK having the waveform shown in the top row of FIG. 1 and 2 on the output signals of the buffer (52) and inverter (53) that received this signal CLK, and NO that received these signals, signal ERI, and signal ER2.
3 and 4 are automatically determined for the output signals of the R circuit (54) and the NOR circuit (55), and Figure 2 (left half part)
It will be as follows.

Next, the NAND circuit (56) and the NAND circuit (57)
Consider the output signals Q1 and Q2 of. Now, considering the period when signal 3 is “1” and signal 4 is “0”, N
Regarding the AND time N (57), since the signal 4 is "0", the signal Q2 becomes "1". As for the NAND circuit (56), the signal 3 is "1" and the signal Q2 is "1".
is "1", so the signal Q1 becomes "0". Conversely, in the period when the signal 3 is "0" and the signal 4 is "1", the signal Q
1 becomes "1" and signal Q2 becomes "0".

Next, the output signal Q3 of the exclusive NOR circuit (70) will be explained. The input terminal of the exclusive NOR circuit (70) receives a signal CLK and a voltage VCR to which the signal CLK is applied via a filter circuit consisting of a resistor (68) and a capacitor (69). The latter voltage VCR has the waveform shown in FIG. 2, but exclusively N.

The exclusive NOR circuit (
70) is equivalently a signal VCRT obtained by delaying the signal CLK by a minute time TI.

Therefore, the exclusive NOR circuit (70) inputs the signal CLK and the signal VCRT and outputs the signal Q3 having the waveform shown in FIG.

Here, since the outputs of inverters (73) and (74) are "1", signal Q1 and signal Q3 are ANDed.
The signal G1 becomes the AC power supply device (10) through the circuit (58).
1) is sent to the control input terminal (15). Furthermore, the signal Q2 and the signal Q3 pass through an AND circuit (59) and become a signal G2, which is sent to the control input terminal (15) of the AC power supply (102). Therefore, in the AC power supply (101), the contact of the control relay (14) is closed only during the period when the signal Gl is "1", and the generated AC power is output to the output terminal (16).
Output from. In the AC power supply (102), the contact of the control relay (14) becomes a leap only during the period when the signal G2 is "1", and the generated AC power is transmitted to the output terminal (I6).
). In this case, when the output of both is switched, the first
Since the time TI, which is a time interval, is provided, the problem of both AC power supply devices outputting AC power at the same time can be avoided. Then, the AC power supply devices (101) and (102
The output from 1 passes through an isolation transformer (30) to a rectifier circuit (
40), it is rectified and smoothed and output as DC power for gate drive. The bottom row of Figure 2 is the output terminal (43)
shows a DC voltage VP, and although its waveform drops slightly during the time period TI, a connected DC output is obtained.

Next, the operation of voltage detection by the voltage sensor (20) will be explained. The output signal VSO becomes "0" when the voltage is present and becomes "1" when the voltage disappears, so that it has the waveform shown in FIG. Now, considering time T1, signal ■S
Since O is “0”, the output signal E of the AND circuit (62)
RO is "0".

At this time, the signal QG outputted via the NOR circuit (71) and 08M (72) is "1", but when the polarity of the signal Q3 is reversed at time T2, 03M (72) becomes "1" at the time interval T
Outputs a "0" level pulse with a time width of TG greater than I. Therefore, the signal VSo rises to "°l" at time T2, but since the signal QG becomes "0", the signal ERO becomes "0".
Continue. Then, when the AC power supply device (101) is normal, the signal VSo is output at time T s (T s = 720 TI).
When changes to 0”°, from then on, regardless of signal QG, signal E
RO is kept at "0". Therefore, the outputs of the AND circuit (60) and the AND circuit (61) become "0" regardless of the signal G1 and the signal G2, and the LATCH circuit (63) and the LATCH circuit (64) that operate with these outputs become "0".
) output signals ERI and ER2 also hold "0". As a result, the failure detection relay (66) and (
67) do not work together.

The above is the operation when both AC power supplies (101) and (102) are normal, but next, let's talk about the operation when it is assumed that an abnormality occurs in either of them and voltage is no longer generated from a certain point of switching. explain.

Now, at time T4 in Fig. 2, the signal G1 rises and the contact of the control relay (14) of the AC power supply (+011) is closed, but the AC power supply (101) is abnormal and its output terminal (
Assume that no voltage is generated from 16).

Therefore, the signal vSO continues to be "1" even after time T4. Eventually, when the time T5 is reached when the signal QG rises, the AND condition of the AND circuit (62) is satisfied and the signal ERO
becomes "1", and at the same time the AND circuit (60) also becomes "1".
When the D condition is satisfied, the signal ER is sent through the LATCH circuit (63).
I becomes ``1'' and the failure detection relay (66) operates, and the oscillator (51) continues to hold the state of the signal CLK at that time.

Due to the change in the signal ERI, the output of the inverter (73) is also inverted and becomes "0", and the AND condition of the AND circuit (58) is not satisfied, so that the signal G1 becomes "0".

When the signal ER1 rises, the output signal 4 of the NOR circuit (55) becomes "0", and in conjunction with this, the signal Q2 and the signal G2 rise to "1". As a result, the AC power supply (102), which is normally inactive, resumes operation and raises its output. In the case of this embodiment, the AC power supply (102>) will be operated continuously from now on.The broken line in the portion after time T4 in Fig. 2 indicates that no abnormality occurred in the AC power supply (101). The waveforms in this case are shown for reference.

As described above, if the AC power supply (101) is abnormal and does not generate voltage, this is immediately detected and the switching operation to the normal AC power supply (+02) is performed, so the rectifier circuit (40) Although the AC power to is interrupted for a time TG which is longer than the normal time TI, a continuous DC voltage vp is obtained as shown in the right part of the bottom row of FIG. In the case of this embodiment, the first time interval referred to in the claims corresponds to the time TI, and the second time interval corresponds to the time (TG-T
I) is equivalent.

In addition, although the above-mentioned embodiment is a case where there are two AC power supply devices, it can be expanded and applied to a system equipped with three or more AC power supply devices based on the same idea.

Further, the present invention can be applied to various power supply circuits that require high reliability, not limited to gate drive use, and can produce similar effects.

〔Effect of the invention〕

Since this invention is configured as described above, it is possible to limit the use of an isolation transformer, which increases the size and cost of the device, to just one unit, and to achieve highly reliable operating characteristics due to parallel redundancy using multiple AC power supplies. is obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a DC power supply according to an embodiment of the present invention, FIG. 2 is a time chart for explaining its operation, and FIG. 3 is a circuit diagram showing a conventional DC power supply. In the figure, (101) and (102) are AC power supply devices,
(16) is the output terminal, (20) is the voltage sensor, (30)
(40) is a rectifier circuit, (42) is a smoothing capacitor, (50) is a command control circuit, and G1 and G2 are operation command signals. Note that the same reference numerals in each figure indicate the same or corresponding parts. RI R2 Figure 2 - Time

Claims (1)

[Claims] A plurality of AC power supplies that output AC power in response to an operation command and each output terminal of which is connected in parallel to each other, a rectifier circuit that inputs AC power, converts it to DC output, and outputs it via a smoothing capacitor; An isolation transformer inserted between the power supply device and the rectifier circuit to electrically insulate the two, a voltage sensor that detects the voltage at the output terminal of the AC power supply device, and cyclically selecting one of the AC power supply devices. The operation commands are sequentially sent out with a predetermined first time gap, and even if a predetermined second time gap elapses after the first time gap elapses, the output of the voltage sensor rises. The DC power supply device includes a command control circuit that selects another AC power supply device other than the AC power supply device selected at that time and sends the operation command when the AC power supply device is not available, and outputs continuous DC power from the rectifier circuit.