JPH0130389B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a DC-DC converter that uses a four-winding transformer and has two power sources, one for regular use and one for emergency use.

[Description of prior art]

Power supply devices that receive power from commercial power sources and backup batteries have a wide variety of applications. Examples of this application include dual AC/DC power supplies for portable radios and televisions, power supplies for measuring instruments and data transmission processing equipment, and large-scale emergency power supplies that supply power to building equipment.

As a conventional device of this type, a floating charging type secondary battery device is often used. In this device, since the terminal voltage of the secondary battery differs significantly between charging and discharging, there was a drawback that a voltage regulator had to be provided on the load side separately from the power supply device. Furthermore, when it is necessary to insulate the commercial power supply circuit from the load equipment connected to this device, there is a drawback that a separate isolation device must be provided from this device.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks and provides a dual-power DC/DC converter that can supply power with little voltage fluctuation to the load connected to the device while being insulated and separated from the commercial power supply circuit. The purpose is to

[Key points of the invention]

The present invention includes a first DC power terminal to which a main power source is connected, a second DC power terminal to which a secondary battery is connected, and a load terminal, and switches or closes the current of the first DC power terminal. a first switching element, a step-up transformer whose primary winding is supplied with a current that is intermittent by the first switching element, and a rectifier that rectifies the current in the secondary winding of this step-up transformer and supplies it to the load terminal. a circuit, a second switching element that switches on and off the current of the second DC power supply terminal, a tertiary winding of the step-up transformer to which current is supplied intermittently by the second switching element; A first control circuit that controls the switching element, a second control circuit that controls the second switching element, and when power supply voltage is supplied to the first DC power terminal, the first control circuit controls the switching element. and automatic control means for operating the second control circuit when there is no power supply voltage at the first DC power supply terminal, the step-up transformer including the secondary battery. Provide a quaternary winding that generates a voltage higher than the charging voltage of
The fourth winding is characterized in that it is connected to the second terminal via a backflow prevention diode.

Further, it is preferable that the first and second control circuits are connected so that their operating power supply current is supplied from the second terminal.

[Explanation based on examples]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIG. 1 is a block diagram showing the structure of this embodiment of the apparatus. Further, FIG. 2 is a waveform diagram showing waveforms of each part of the device of this embodiment.

First, the configuration of this embodiment device will be explained based on FIG. This embodiment device includes a two-power DC-DC converter (hereinafter referred to as a DC-DC converter) 10, a rectifying and smoothing circuit (hereinafter referred to as a rectifier) 20, a DC power supply circuit 30, and a load. 40 and a first switch 45.
Here, the DC-DC converter 10 includes a step-up transformer 100 with a quaternary winding, a first switching element 111, a second switching element 112, and a first backflow prevention diode (hereinafter referred to as the first diode). ) 121 and
A second backflow prevention diode (hereinafter referred to as a second diode) 122, a diode 123 as a rectifier circuit, a first control circuit 131, a second control circuit 132, and a first voltage divider 141. , a second voltage divider 142, a negative logic element 150, and a second switch 160. Rectifier 20
is connected to an external AC commercial power source and becomes the main power source.
The DC power supply circuit 30 includes a secondary battery. The first switching element 111 and the second switching element 112 are transistors.

The output of the rectifier 20 is connected to the first DC power terminal of the DC-DC converter 10, and the output of the DC power circuit 30 is connected to the second DC power terminal of the DC-DC converter 10, so that the DC-DC conversion is performed. The load terminal of the device 10 is connected to the input of a load 40 via a first switch 45. Further, the first DC power terminal of the DC-DC converter 10 is connected to the primary winding 101 of the step-up transformer 100.
and the input of the first voltage divider 141, and the first output of the first voltage divider 141 is
The output of the negative logic element 150 is connected to the enable signal terminal of the second control circuit 132, and the output of the negative logic element 150 is connected to the enable signal terminal of the first control circuit 131. The output is connected to a common potential. Also, DC−
The second DC power supply terminal of the DC converter 10 is connected to one terminal of the third winding 103 of the step-up transformer 100, one terminal of the fourth winding 104, and the second switch 160. The switch 160 is connected to the control power terminal of the first control circuit 131 and the control power terminal of the second control circuit 132.

The other terminal of the first winding 101 of the step-up transformer 100 is connected to the anode of the first diode 121, and the cathode of the first diode 121 is connected to the collector of the first switching element 111. The base of the element 111 is the first control circuit 13
The emitter of the first switching element 111 is connected to the second control signal terminal of the first control circuit 131 and the common potential. Further, the fourth winding 10 of the step-up transformer 100
The other terminal of 4 is connected to the cathode of the second diode 122, and the anode of the second diode 122 is connected to the common potential. Further, the other terminal of the third winding 103 of the step-up transformer 100 is connected to the collector of the second switching element 112, and the base of the second switching element 112 is connected to the second control circuit 13.
The emitter of the second switching element 112 is connected to the second control signal terminal of the second control circuit 132 and the common potential.

One terminal of the second winding 102 of the step-up transformer 100 is connected to the anode of the diode 123, and the cathode of the diode 123 is connected to the load terminal of the DC-DC converter 10.
The other terminal of the second winding 102 of 0 is connected to the common potential, and the cathode of the diode 123 is connected to the input of the second voltage divider 142, and the first output of the second voltage divider 142 is First control circuit 131
and the sense signal terminal of the second control circuit 132, and the second voltage divider 142
A second output of is connected to a common potential.

Next, the operation of this embodiment device will be explained based on FIGS. 1 and 2. Here, 1 to 4 in Figure 2
The waveform diagram shows the waveform when input from the rectifier 20 which is the main power supply, 5 to 7 show the waveform when input from the DC power supply circuit 30 including the secondary battery, and (1) shows the waveform when input from the DC power supply circuit 30 including the secondary battery. 2 is the waveform of the collector voltage of the first switching element 111, 3 is the waveform of the cathode voltage of the second diode 122, and 4 is the waveform of the anode voltage of the third diode 123. In addition, 5 is the waveform of the base voltage of the second switching element 112, 6 is the waveform of the collector voltage of the second switching element 112, and 7 is the waveform of the third diode 1.
23 shows the waveform of the anode voltage of No. 23.

Here, if the output voltage of the DC power supply circuit 30 maintains the specified value, the first switching element 111
is in a conductive state, the step-up transformer continues to accumulate magnetic energy, and this first switching element 1
11 becomes non-conductive and the takeover flyback period begins, the windings between the primary winding 101 and the tertiary winding 103 of the step-up transformer are closed so that the collector of the second switching element 112 does not take a negative value. The ratio is predetermined.

There are two types of normal operation of the DC-DC converter 10. The first normal operation mode is when the main power voltage is established via the rectifier 20, and in this case, power is supplied to the load 40 and the secondary battery included in the DC power supply circuit 30 is charged. done at the same time. The second normal operating mode is when the main power supply voltage drops abnormally; in this case,
Power is continuously supplied to the load 40. During these two types of normal operation, the first switch 45
and second switch 160 are both closed. Further, the selection of the first normal operation mode and the second normal operation mode is determined depending on whether the voltage value of the AC voltage that supplies power to the rectifier 20 is equal to or higher than a specified value. That is, when this voltage value is equal to or higher than the specified value, the first control circuit 131 is put into an operating state by the voltage signal applied to the enable terminal of the first control circuit 131 via the voltage divider 141, and further, This voltage signal is applied to the negative logic element 1
A voltage signal applied to the enable terminal of the second control circuit 132 via 50 disables the second control circuit 132 and places the circuit in a state in which a first normal mode of operation can be performed. In addition, the rectifier 20
If the voltage value of the alternating current voltage that powers The circuit state is such that the operating mode can be executed.

First, in the first normal operation mode, the magnetic energy of the first winding 101 of the step-up transformer 100 is accumulated during the conduction period of the first switching element 111 controlled by the control signal of the first control circuit 131. When this first switching element 111 becomes non-conductive, it connects to the third diode 123 via the second winding 102, the second diode 122 via the fourth winding 104, or the second through the winding 102 of the third diode 123 and the fourth winding 10
4 to the second diode 122. In the circuit including the second diode 122, the distributed power charges the secondary battery included in the DC power supply circuit 30, while in the circuit including the third diode 123, the distributed power charges the secondary battery included in the DC power supply circuit 30. Power is supplied to the load 40 via one switch 45.

When the first switch 45 is operated to open the circuit in this first normal operation mode, all the power output from the rectifier 20 is consumed to charge the secondary battery included in the DC power supply circuit. .

Further, the voltage value of the load terminal of the DC-DC converter 10 is detected, and a signal corresponding to this is given to the first control circuit 131 and the second control circuit 132, where a charging control signal is generated. Charging control of the secondary battery is performed in the circuit state of the first normal operation mode.

Next, in the second normal operation mode, power is supplied from the DC power supply circuit 30. In this case, the magnetic energy of the third winding 103 of the step-up transformer accumulated during the conduction period of the second switching element 112 controlled by the control signal of the second control circuit 132 is When element 112 becomes non-conductive, it is supplied to third diode 123 via second winding 102 . In the circuit including the third diode 123, this supplied power is fed to the load 40 via the first switch 45. In this case, the first winding 101 and the fourth winding 104
A voltage is induced in the diode, but power is not distributed due to the backflow prevention operations of the first diode and the second diode, respectively.

In the device of this embodiment, the control circuit is composed of a first control circuit 131 and a second control circuit 132, but the present invention can also be implemented by combining them into one control circuit.

Further, the present invention can also be implemented by using a voltage corresponding to the voltage at the second DC power supply terminal as the detection voltage for executing charging control of the secondary battery that is being supplied with power to the load 40.

〔Effect of the invention〕

As explained above, the present invention allows charging control to be set freely in the same way as conventional float type DC power supplies, so the life of the secondary battery is maintained and automatic switching between commercial power supply and secondary battery is possible. Can be executed continuously over time. Furthermore, since the voltage fluctuation rate of the voltage applied to the load is extremely good, there is no need to provide a voltage regulator separate from the power supply circuit on the load side, and therefore the installation conditions for devices serving as the load are eased. Furthermore, since the commercial power supply circuit and the load circuit can be insulated and separated by the step-up transformer, there is no concern that leakage current from the commercial power supply circuit will enter the load circuit.
Therefore, it can be used as a stabilized uninterruptible power supply for medical equipment, etc. that requires safety, and a remarkable effect can be produced.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing the configuration of an apparatus according to an embodiment of the present invention. FIG. 2 is a waveform diagram showing voltage waveforms of main parts of the device according to the embodiment of the present invention. 10...DC-DC converter, 20... Rectifier, 3
0...DC power supply circuit, 40...Load, 45, 16
0...Switch, 100...Step-up transformer, 11
1,112...Switching element, 121,122,12
3... Diode, 131, 132... Control circuit, 141, 142... Voltage divider, 150... Negative logic element.

Claims (1)

[Claims] 1. A first DC power supply terminal to which a main power supply is connected;
A first switching element that switches on and off the current of the first DC power supply terminal, which includes a second DC power supply terminal to which a secondary battery is connected and a load terminal, and a current that is interrupted by the first switching element. a step-up transformer that supplies the primary winding; a rectifier circuit that rectifies the current in the secondary winding of the step-up transformer and supplies it to the load terminal; and a second circuit that opens and closes the current of the second DC power terminal. a switching element; a tertiary winding of the step-up transformer to which current is supplied intermittently by the second switching element; a first control circuit that controls the first switching element; and a second switching element. and a second control circuit that controls the first DC power terminal, and when sufficient power supply voltage is supplied to the first DC power terminal, the first control circuit is operated to control the power supply voltage of the first DC power terminal. In a DC-DC converter equipped with automatic control means for operating the second control circuit when insufficient or depleted, a quaternary winding that generates a voltage higher than the charging voltage of the secondary battery in the step-up transformer; A two-power DC-DC converter, characterized in that the quaternary winding is connected to the second terminal via a reverse current prevention diode. 2. The two-power DC-DC converter according to claim 1, wherein the first and second control circuits are connected such that their operating power supply current is supplied from the second terminal.