JPH0118663B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a simple, low-cost, and highly reliable power conversion device.

In order to increase the reliability of conventional power converters that supply DC power to loads, by inputting multiple DC power supplies, it has uninterruptible characteristics, that is, it can supply power to the load even if one of the input DC power sources experiences a power outage. It is known that it continues to do so.

Figure 1a shows an example of a conventional power converter that uses two DC power supplies with significantly different voltages as input power supplies.The output voltage of the DC power supplies is
After being input to the DC-DC converter and converted to a voltage equal to the DC power supply, it is input to the DC-DC converter through each diode together with the output voltage of the DC power supply, and power is supplied from the DC-DC converter to the load. It's becoming like that. Therefore, in the above device, power is normally supplied to the load from both the DC power sources connected with the diode-or, but even if an abnormality such as an accident or power outage occurs in either of the DC power sources, the load will receive uninterrupted power. can be supplied. However, generally DC-DC
Since converters cannot handle large differences in input voltage and the voltage levels must be nearly the same,
Two DC-DC converters were required.

FIG. 1b shows an example of an uninterruptible power converter configured with an AC power source and a battery as inputs. When AC power is input, the difference is that a rectifier for converting AC into DC is added compared to the case of FIG. 1a. Such a configuration is often used as a method of imparting uninterruptible characteristics to a small capacity power supply used in communication terminal equipment. Power supplies for terminal devices especially need to be made smaller, but generally speaking, the lower the DC voltage obtained from a battery, the smaller the volume occupied by the battery. Therefore, lower the voltage obtained from the battery,
Converting the high voltage obtained from the AC power source to match the voltage of the battery is advantageous for downsizing the power supply section. Therefore, as shown in FIG. 1b, a method is often used in which the AC voltage is rectified, then stepped down by a DC-DC converter, and then input to the DC-DC converter in accordance with the battery voltage.

FIG. 1c shows a specific circuit of the device shown in FIG. 1b when using a DC-DC converter and a ringing chain converter known as a DC-DC converter. In the figure, 1 is a commercial AC power supply, 2 is a rectifier, 3-1
and 3-2 is a DC-DC converter, 4 is a battery,
5 and 6 are diodes, and 7 is a load. Note that since the operation of the ringing chain converter is well known, it will not be specifically explained here.

As described above, in the conventional power converter which inputs a plurality of DC power supplies having widely different voltage levels, it is necessary to equalize the voltage level of each power supply in advance and input it to the final stage converter. Therefore, it is necessary to provide a plurality of converters in one device, which results in a complicated device configuration, poor reliability, and high cost.

In order to eliminate the drawbacks of these power converters, the present invention makes it possible to input a plurality of DC powers with different voltage levels into one converter, and also makes it possible to input a plurality of DC powers with different voltage levels into a single converter. The device is designed to be able to be charged at the same time, and its purpose is to simplify the device configuration and improve reliability. The drawings will be described in detail below.

FIG. 2 shows a first embodiment of the present invention.
Here, an example using a single-stone converter is shown. In Figure 2, 10-1, 10-2...10-n
are a plurality of DC power supplies with voltages V ₁ , V ₂ . . . Vn, respectively, 20 is a transformer, 30 is a switching element,
For example, the switching transistor 40 is a control transistor.
In the driving circuit, 50-1, 50-2...50-n are connecting diodes, 61 and 62 are rectifying diodes, 63 is a smoothing coil, 64 is a smoothing capacitor, and 7 is a load. The transformer 20 has a primary winding 2 having intermediate taps T1, T2...T(n- ₁ ).
01 and a secondary winding 202, the number of turns from one end 201a to the other end 201b of the primary winding 201 is _N1 , and from the one end 201a to each intermediate tap T1, T2...T (n- ₁ ). windings of
Let N ₂ , N ₃ ...Nn.

The primary winding 201 of the transformer 20 has one end 20
1a is connected in series to the collector of the switching transistor 30 which is controlled on/off by the control/drive circuit 40, and a connecting diode 50 is connected at the other end 201b and intermediate taps T1, T2...T(n- ₁ ). 1,50-2...50-n to the (+) pole of the DC power supplies 10-1, 10-2...10-n, and further the DC power supplies 10-1, 10-2...10
The (-) pole of -n is collectively connected to the emitter of the switching transistor 30.

Since the structure is as described above, the DC power supply 10
-1, 10-2...10-n DC power is supplied to the transformer 2 by switching the switching transistor 30 on and off.
0 is transmitted from the primary side to the secondary side, and after being rectified by rectifying diodes 61 and 62, it is converted to DC power of a desired voltage value through a filter consisting of a smoothing coil 63 and a smoothing capacitor 64. supplied to Here, DC power supply 10
-1, 10-2, 10-n voltages V ₁ , V ₂ ...Vn
and one end 201a of the primary winding 201 of the transformer 20
to the other end 201b and intermediate taps T1, T2...
By selecting _the ratio of _the number _of turns _{N 1 , N 2} . The voltage of taps T1, T2...T(n- ₁ ) can be made almost equal to the voltage of each power supply, and each connection diode creates a diode-OR connection between the power supplies, and power is supplied from each power supply in the same way. can do. In addition, for example, the voltage of the DC power supply 10-1
V ₁ is the voltage of the DC power supply 10-i of the other intermediate tap T(i- ₁ ) (number of turns Ni, where i = 2, 3...n)
The number of turns N ₁ , Ni is set so that the voltage N ₁ /NiVi applied to the other end 201b by Vi is higher than the voltage drop of the connecting diode (for example, 2 to 3 V).
(V ₁ > N ₁ /NiVi), power is supplied only from the DC power supply 10-1, and the other DC power supplies 10-i
The power supply from the connection diode 50-i is blocked by the connection diode 50-i. At this time, DC power supply 10-1
Only in the event of an accident, power outage, etc., use another DC power source 1.
Power will be supplied from 0-i. In this case, the input voltage will change, but the above-mentioned difference is within an allowable range, and the output voltage is controlled to a predetermined voltage by the control/drive circuit 40. Note that the control/drive circuit 40 is realized by a known electronic circuit, IC, etc., and therefore will not be described in detail.

In this way, according to the above embodiment, it is possible to input a plurality of DC voltages with different voltages without requiring any other converter, and to input these powers simultaneously by diode-OR connection. Only electric power can be input preferentially, and a highly reliable power conversion device can be provided with a simple configuration.

FIG. 3 shows a second embodiment of the present invention,
An example is shown in which a full bridge converter and a push pull converter are combined. That is, 21 in the figure
is a transformer having a primary winding 211 and a secondary winding 212, and 31a, 31b, 31c, and 31d are switching transistors forming a bridge.
The primary winding 211 has a center tap T at its center.
1, the center tap T1 and one end 211a
Intermediate taps T2, T3...T(n- ₁ ) are placed between
Further, intermediate taps T2', T3'...T(n- ₁ )' are provided between the center tap T1 and the other end 211b, and each intermediate tap T is connected from one end 211a to
2, T3...Number of turns up to T(n- ₁ ) and the other end 211b
The number of turns from T2' to each intermediate tap T2', T3'...T(n- ₁ )' is equal. Here, DC power supply 1
0-1 is connected to both ends of the bridge via a connecting diode 50-1, and is connected to the DC power supply 10.
-2 is connected to the center tap T1 via the diode 50-2, and further to the DC power supply 10-3, 10-4...1
0-n are diodes 50-3 and 50-3',
50-4 and 50-4'...50-n and 50
- n' to intermediate taps T2 and T2', T3
and T3'...connected to T(n- ₁ ) and T(n- ₁ )', respectively. Therefore, for the DC power supply 10-1, the switching transistors 31a, 31
d, 31b, and 31c operate as a full bridge converter that alternately opens and closes to supply power,
Switching transistors 31c and 31d are used for DC power supplies 10-2, 10-3...10-n.
operates as a push-pull converter that alternately opens and closes to supply power, and power can be supplied to the secondary side of the transformer 21 from either power source.
DC power of a predetermined voltage can be supplied to the load 7 via the capacitor 64. Note that the push-pull converter generates twice the voltage in the transformer as the full bridge converter, so the voltage V ₂ of the DC power supply 10-2 is equal to the voltage V ₁ of the DC power supply 10-1.
1/2, other DC power supplies 10-3, 10-4...
The voltage of 10-n needs to be 1/2 or less. Other configurations and effects are similar to those of the first embodiment.

FIG. 4a shows a third embodiment of the present invention, in which a commercial AC power source 1 and a battery 4 are used as the DC power source, and a ringing chain converter is used as the converter. That is, the commercial AC power supply 1 is converted to DC by the rectifier 2, connected to the primary winding 221 of the transformer 22 via the diode 51, and the battery 4 is connected to the primary winding 221 of the transformer 22 via the diode 5.
2 to the intermediate tap T1 of the transformer 22, and a control/drive circuit 41 is connected between the control winding 222 separately provided in the transformer 22 and the base/emitter of the switching transistor 32. The electric power obtained from the secondary winding 223 of the transformer 22 is rectified and smoothed by turning it on and off, and then supplied to the load 7.
Here, of the two inputs of the converter, the battery 4 generally lasts for a shorter time than the commercial power supply 1, so compare the voltage V ₁ of the commercial power supply 1 with the voltage V ₂ of the battery 4 and find that V ₂ /N ₂ <V ₁ /N ₁ (where N ₁ is the number of turns from one end 221a to the other end 221b of the primary winding 221, N ₂ is the number of turns from one end 221a to the intermediate tap T1), and Normally, the diode 52 is turned off to block power supply from the battery 4, and power is supplied to the transformer 22 only from the commercial power source 1. In this state, if the voltage V ₁ drops due to an accident, power outage, etc. in the commercial power supply 1,
V ₂ /N ₂ >V ₁ /N ₁ , the diode 52 becomes conductive, power is supplied from the battery 4 to the transformer 22, and the load 7
can continue to be supplied with DC power at a desired voltage value.

FIG. 4b shows a fourth embodiment of the present invention, in which the battery 4 connected to the intermediate tap in the third embodiment is connected to another primary winding. be. That is, the transformer 23 has a primary winding 231 with N ₁ turns and a primary winding 2 with N ₂ turns.
32, a control winding 233, and a secondary winding 234, the commercial AC power supply 1 is connected to one end of the primary winding 231 through a diode 51, and the battery 4 is connected to the primary winding 232 through a diode 52. The other ends of the primary windings 231 and 232 are respectively connected to the collector of the switching transistor 32, so that power is supplied to the transformer 23 from each winding. Note that the other configurations and effects are similar to those of the third embodiment.

FIG. 5 shows a fifth embodiment of the present invention in which a known Royer converter is used.
The DC voltage obtained by rectifying the rectifier 2 is applied to the center tap T1 of the primary winding 241 of the transformer 24.
and two switching transistors 33a, 33
A diode is connected between two intermediate taps T2, T2' provided in the transformer 24 and the emitters of the switching transistors 33a, 33b. 52, 52',
Power is supplied to the load 7 by alternately opening and closing the transistors 33a and 33b. In addition, in the case of this embodiment as well, in the primary winding 241 of the transformer 24, one end 241a
to the intermediate tap T2, and the other end 241b.
The number of turns from T2' to intermediate tap T2' must be the same.

FIG. 6 shows a sixth embodiment of the present invention,
An embodiment using a rechargeable secondary battery as a battery and having a ringing chain converter configuration including a charging/control circuit for the secondary battery is shown. The transformer 25 includes a primary winding 251 having intermediate taps T1 and T2, a control winding 252, and a secondary winding 253. A switching transistor 32 is connected to one end 251a of the primary winding 251, and a switching transistor 32 is connected to one end 251a of the primary winding 251. edge 2
51b is connected to the commercial AC power supply 1 which is rectified by the rectifier 2 via the diode 51, and the secondary battery 8 is connected to the intermediate tap T1 via the diode 52 and a microresistance R _B. is the charging/control circuit 90 and the diode
It is connected to the secondary battery 8 via D _F. Here, the voltages V ₁ and V ₂ of the commercial power supply 1 and the secondary battery 8 are
and the number of turns N ₁ between the primary winding of the transformer 25 from one end 251a to the other end 251b and one end 25
The relationship between the number of turns N ₂ from 1a to the intermediate tap T1 is normally set such that V ₂ /N ₂ <V ₁ /N ₁ in order to supply power only from the commercial power source 1.

The charging/control circuit 90 consists of a rectifier 91, a series dropper transistor 92, a control IC 93 (for example, μA723), etc. The rectifier 91 rectifies the power obtained from the intermediate tap T2, and the transistor 9
2 is stabilized at a level suitable for charging the secondary battery 8 by a series dropper circuit controlled by the output current of the stable output terminal of the control IC 93, and the voltage is stabilized at a level suitable for charging the secondary battery 8 via the diode _DF . In addition to 8, a small resistor R _B is connected between the current limit terminal and the current selection detection terminal of the above IC93.
The output current limiting transistor in the IC 93 is turned on by the amount of voltage drop, cutting off the output current to the transistor 92 and turning off the charging voltage.

Therefore, according to the above embodiment, normally the commercial power supply 1
Power is input to the transformer 25 only from the transformer 25, DC power of a predetermined voltage is supplied to the load side, and the secondary battery 8 is charged by the power input to the charging/control circuit 90 via the intermediate tap T2. Ru. When an accident, power outage, etc. occurs in the commercial power source 1 and its voltage drops, the diode 52 is turned on, power is input from the secondary battery 8 to the transformer 25, and the load 7 is continuously supplied with DC power at a predetermined voltage. On the other hand, since the output current from the secondary battery 8 flows through the minute resistance R _B at this time, a voltage drop occurs and the charging/control circuit 90 turns off the charging voltage to the secondary battery 8 . That is, the discharge current from the secondary battery 8 is prevented from flowing back into the secondary battery 8 through the charging/control circuit 90. After that, when the commercial power supply 1 is restored and its voltage is restored, the diode 52 is turned off and the power supply from the secondary battery 8 is stopped, and power is supplied only from the commercial power supply 1, and at the same time the voltage drop across the microresistance R _B is reduced. Since the battery runs out, the charging/control circuit 90 starts operating again and charges the secondary battery 8.

In this way, since power is normally supplied only from the commercial power source and the secondary battery is charged at the same time, the secondary battery can always store sufficient power, and if the voltage of the commercial power source drops, Advantages include that sufficient power can be supplied to the load from the secondary battery at any time, and that there is no risk of wasting power because charging is not performed at that time.

As explained above, according to the present invention, DC power is input to the series circuit of the primary winding of the transformer and the switching element, and by controlling the switching element on and off, the secondary winding of the transformer is controlled. In a power conversion device that supplies DC power with a desired voltage value to a load, a plurality of DC power supplies with different voltages are connected in parallel to the primary winding of the transformer so that the ratio of the voltage value and the number of turns is approximately the same. Because it is connected, power sources with widely different voltages can be input to one converter without the need to install a converter for each power source as in the past. It is possible to realize a power conversion device having uninterruptible characteristics operated by a battery with a simple circuit, further improve reliability, and provide it at a low cost. In addition, at least one of the plurality of power sources is a secondary battery, and the system charges the secondary battery and detects whether or not power is being supplied from the secondary battery, and prevents charging while it is supplying power. A device equipped with a charging/control circuit that controls the charging and control circuits allows an independent power source that always stores sufficient power to be maintained, and eliminates wasted power consumption when power is supplied from the secondary battery. It is possible to provide this type of power conversion device with higher reliability without having to do so.

[Brief explanation of drawings]

The drawings are for explaining the present invention and are shown in Figure 1a.
1 is a block diagram showing an example of a conventional power conversion device having uninterruptible characteristics, FIG. 1b is a block diagram showing another example of a conventional power conversion device having uninterruptible characteristics, and FIG. FIG. 2 is a detailed circuit diagram showing an example of the device shown in FIG. 2, FIG. 3 is a circuit diagram showing a first embodiment of the power conversion device of the present invention, and FIG. , Figure 4a and Figure 4b
5 is a circuit diagram showing the fifth embodiment of the present invention, and FIG. 6 is a circuit diagram showing the sixth embodiment of the present invention. It is a diagram. 1... Commercial power supply, 2... Rectifier, 4... Battery, 7... Load, 8... Secondary battery, 10-1, 10-2... 10-
n... multiple DC power supplies with different voltages, 20, 21,
22, 23, 24, 25...trans, 201, 2
11,221,231 and 232,241,2
51...Transformer 20, 21, 22, 23, 24,
25 primary windings, 30, 31a, 31b, 31
c, 31d, 32, 33a, 33b... switching transistor, 40, 41... control/drive circuit,
50-1, 50-2... 50-n, 51, 52... Connection diode, 61, 62... Rectifying diode, 63... Smoothing coil, 64... Smoothing capacitor, 90... Charging/control circuit.

Claims (1)

[Claims] 1. Direct current power is input to a series circuit of a transformer's primary winding and a switching element, and the switching element is turned on and off to provide a desired load to the secondary winding of the transformer. In a power conversion device that supplies DC power with voltage values, a plurality of DC power supplies with different voltages are connected in parallel to the primary winding of the transformer so that the ratio of the voltage value and the number of turns is approximately the same. Characteristic power converter. 2 DC power is input into a series circuit between the primary winding of the transformer and a switching element, and by controlling the switching element on and off, DC power of a desired voltage value is applied to the load on the secondary winding side of the transformer. In the power conversion device to be supplied, a plurality of DC power sources including at least one secondary battery are connected in parallel to the primary winding of the transformer so that the ratio of the voltage value and the number of turns is approximately the same, and the A power conversion device characterized by being equipped with a charging/control circuit that charges a secondary battery, detects whether or not power is being supplied from the secondary battery, and controls not to charge during the supply period. .