JPH01231662A - Dc power supply - Google Patents

Abstract

PURPOSE:To decrease the number of voltage conversion stages and to improve the efficiency of conversion, by converting an AC voltage from a three phase AC power source directly into a high frequency AC voltage. CONSTITUTION:A DC power supply is composed of an input filter 3 for a three- phase AC power source, a transformer 5, an output rectifier 6, an output filter 7 and others to supply a load 8 with power. In this case, said power supply is provided with a switching part 10 and a control circuit 11 to switch AC voltage from said three-phase AC power source 1 at a higher frequency by said switching part 10 via said input filter 3. Then, a high frequency AC voltage is generated on the output side of said transformer 5. Also, said control circuit 11 detects each line voltage from the three-phase AC power source 1, controls the ON pulse width of semiconductor switches 12-17 between respective lines so that said pulse width is proportional to said line voltage, and determines which switch to be turned ON. Thus, the efficiency of conversion is improved, because said AC voltage can be directly converted into a high frequency AC voltage.

Description

[Detailed description of the invention] [Industrial application field] The present invention has high conversion efficiency (and can be made smaller and lighter).

This invention relates to a DC power supply device that can generate a sine wave at its input terminal.

[Conventional technology]

FIG. 5 is a block diagram showing a conventional DC power supply device. As shown in the figure, 2 In the conventional DC power supply device, the AC voltage from the 23-phase AC power supply 1 is full-wave rectified in the input rectifier 2, and the DC voltage is smoothed in the input filter 3 consisting of a choke and a capacitor. After obtaining the DC voltage, the switching unit 4 switches the DC voltage on and off at a high frequency, and the transformer 5
The high frequency AC voltage obtained from the secondary side of the output rectifier 6 and an output filter consisting of a choke and a capacitor,
A DC voltage is obtained by rectification and smoothing, and the DC voltage is supplied to the load 8. Further, the control circuit 9 detects the output voltage and performs pulse width modulation control to control the on period of the switch in the switching section 4, thereby stabilizing the DC voltage of the two outputs.

[Problem to be solved by the invention]

However, in this conventional DC power supply, the three-phase AC power supply I
Since the alternating current voltage is first converted into direct current voltage and then converted into high frequency alternating current voltage by the switching section 4, a large loss occurs in the manual rectifier section 2 and the switching section 4, resulting in a problem that the conversion efficiency decreases. . For this reason, there are problems in that the cooling fins become larger, and the number of parts increases, making the device larger and more expensive. Furthermore, since the three-phase AC voltage is once full-wave rectified, the input current flows only during the period when the line voltage is highest, and there is a problem that the input current contains many harmonics.

[Means to solve the problem]

In order to eliminate the following drawbacks, the present invention provides a three-phase AC power supply, an input filter for reducing the noise of the three-phase AC power supply, and a transformer that switches at a frequency higher than the frequency of the three-phase AC power supply. a switching section consisting of a plurality of semiconductor switches that generate a high frequency AC voltage on the output side of the;
An output rectifier and an output filter that rectify and smooth the AC output from the transformer, and each semiconductor switch corresponding to the on-pulse width proportional to each line voltage from the three-phase AC power supply are sequentially turned on, and each line voltage is The switching unit is controlled so that a series of operations of supplying power from the transformer to the load side and returning the excitation energy of the transformer to the three-phase AC power supply via the semiconductor switch are performed in one conversion cycle. The present invention provides a DC power supply device characterized by comprising a control circuit.

[Effect]

According to such a DC power supply device, the AC voltage from the three-phase AC power converter can be directly converted into high-frequency AC voltage at the switching section, so the number of power conversion stages can be reduced, and the conversion operation and
Improved performance. Also, since the input terminal can be made into a sine wave,
The harmonic components of the input current can be significantly reduced, and the shadow of noise etc. can be reduced on devices that share a power supply! not give.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In the figure, 1 is a three-phase AC power supply, 3 is a manual filter,
5 is a transformer, 6 is an output rectifier, 7 is an output filter, 8
is a load, 10 is a switching section, 11 is a control circuit, 1
2 to 17 are semiconductor switches.

The AC voltage from the three-phase AC power supply 1 is switched through the single-power filter 3 at a switching unit 10 at a frequency higher than the frequency of the commercial three-phase AC power supply, and a high-frequency AC voltage is generated on the output side of the transformer 5. This transformer 5
The AC output is rectified by the output rectifier 6, smoothed by the output filter, and supplied to the load 8 as a DC output.

The control circuit 11 detects each line voltage from the three-phase AC power supply 1 and controls the on-pulse width of the semiconductor switch inserted between each line to be proportional to the line voltage.
Decide which semiconductor switch to turn on.

FIG. 2 is a block diagram showing the control circuit 11.

A method of controlling the switching section 10 will be explained using this figure.

The on-pulse width of the semiconductor switches 12 to 17 is 1 = S.
Compare the waveform obtained by dividing and rectifying the line voltage VR,, S-T line voltage V,, TR line voltage VTR by full-wave rectifier circuits 21 to 23, and the outputs of pulse generation circuits 24 to 26. Vessel 2
7 to 29.

The on-pulse width can be proportional to the line voltage.

Next, which semiconductor switch is turned on will be explained. By comparing the line voltage and the ground voltage by the comparators 31 to 33, the positive/negative relationship between the line voltages is expressed by the outputs of the three comparators 31 to 33. Based on these three signals, the switch position determination circuit 30 determines three sets of two semiconductor switches so that current flows from the positive line voltage to the negative line voltage through the transformer, and further transfers the excitation energy of the transformer to the three-phase AC power supply. Determine two semiconductor switches for feedback to the side. For example, R-5, S-T, T
After supplying power to the load side in the order between −9 and 9, the excitation energy is changed to I? -3, at point Q in FIG. 3, first turn on the semiconductor switch 12.16 and
The semiconductor switch 14.1
6. Sequentially turn on the semiconductor switches 12 and 17 and turn on S-T.
After supplying power to the load side from between TR and R, the switch 13.15 is turned on to feed back the power between R and 8.

The control operation will now be described in detail with reference to FIG. 4, which shows waveforms of various parts at point Q in FIG. 3. When the operation signal comes from the switch determination circuit 30 shown in FIG. 2 to the pulse generation circuit 24, the pulse generation circuit 24 generates a pulse a shown in FIG.
The on-pulse width of the semiconductor switch inserted between R-3 is determined by generating one pulse of
This on-pulse width signal is input to the switch determination circuit 30.

Since the voltage between R and 3 is positive in the switch determination circuit 30, the 5th
In order to turn on the semiconductor switch 12.16 shown in the figure, the on-pulse width signal x1 shown in FIG.

Immediately after the conductor switches 12 and 16 are turned off, an operating signal is sent to the pulse generation circuit 25 shown in FIG. The pulse generating circuit 25 generates one pulse C shown in FIG. 4, and compares it with the output d of the full-wave rectifier circuit 22 shown in FIG. 4 by a comparator 28, which is inserted between S and T. The on-pulse width of the semiconductor switch is determined.

This on-pulse width signal is input to the switch determination circuit 30. Since the voltage between ST and T is negative in the switch determination circuit 30, in order to turn on the semiconductor switch 14.16 shown in FIG. 1, the on-pulse width signal x2 shown in FIG. Immediately after the semiconductor switch I11.16 is turned off.

An operation signal is sent to the pulse generation circuit 26 shown in FIG.

The pulse generating circuit 26 generates one pulse e shown in FIG. 4, and compares it with the output f of the full-wave rectifier circuit 23 shown in FIG. The on-pulse width of the semiconductor switch is determined, and this on-pulse width signal is input to the switch determining circuit 30. Since the voltage between T and R is negative in the switch determining circuit 30, in order to turn on the semiconductor switches 12 and 17 shown in FIG. 1, the on-pulse width signal x3 shown in FIG.
．． 17 drive circuit 34, 39, semiconductor switch 1
In order to turn on the semiconductor switch 13.15 immediately after 2.17 turns off.

The on-pulse width signal x 4 shown in Figure 4 is applied to the semiconductor switch 1.
3.15 to the drive circuit 35.37, and the excitation energy of the transformer is returned to the three-phase AC power supply side. By repeating this operation, power is supplied from each line to the load side in one conversion period with an on-pulse width proportional to the line voltage, and the input current becomes a sine wave with the switching frequency component removed by the input filter 3. Further, since the pulse generation circuit has a function of changing the slope of the pulse depending on the output voltage, the output voltage becomes a stable DC voltage. For example, as the output voltage increases, α shown in Figure 4 increases and the slope becomes steeper.
It operates to shorten the on-pulse width while making it proportional to the line voltage.

〔Effect of the invention〕

As explained below, in the DC power supply device according to the present invention, the switching section has the function of directly converting the AC voltage from the three-phase AC power supply into high-frequency AC voltage, so the number of power conversion stages can be reduced. This has the advantage of improving conversion efficiency.

Furthermore, there is an advantage that a heat dissipation fin for cooling the input rectifying section is not required, and by further increasing the switching frequency, the device can be made smaller, lighter, and lower in cost. Furthermore, since power is supplied from each line to the load side in one conversion period with an on-pulse width proportional to the voltage between the five lines, the input current can be made into a sine wave. Therefore, the harmonic components of the input current can be significantly reduced, and there is an advantage that devices sharing the power supply are not affected by noise or the like.

[Brief explanation of the drawing]

1 to 4 are diagrams for explaining an embodiment of the present invention, and FIG. 5 is a diagram for explaining a conventional DC power supply device. l... 3-phase AC power supply 2... manual rectifier section 3...
・Input filter 4... Switching section 5...
Transformer 6--Output rectifier 7-Output filter 8-Load 9-Control circuit
10... Switching section 11... Control circuit 1
2-17...Semiconductor switches 21-23...Full-wave rectifier circuit 24-26...Pulse generation circuit 27-29.
... Comparator 30 ... Switch determination circuit 3
1 to 33...Comparator 34 to 39...Pulse generation circuit 40 to 42...Inverting circuit Patent applicant Origin Electric Co., Ltd. Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] A three-phase AC power source, an input filter for the three-phase AC power source, and a plurality of semiconductors that switch at a frequency higher than the frequency of the three-phase AC power source and generate a high-frequency AC voltage on the output side of a transformer. a switching unit consisting of a switch; an output rectifier and an output filter that rectify and smooth the AC output from the transformer; and each of the semiconductor switches corresponding to each line voltage from the three-phase AC power supply with an on-pulse width proportional to each line voltage. is sequentially turned on, power is supplied from each line to the load side, and the excitation energy of the transformer is returned to the three-phase AC power supply via the semiconductor switch. A series of operations are performed in one conversion cycle. , and a control circuit that controls the switching section.