JP2013211960A - Power-supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power-supply device capable of easily controlling the supply of power when the supply of AC power is interrupted.SOLUTION: A power-supply device includes: a first rectifier circuit section 11 rectifying an AC input from an AC input section 10 and outputting a DC voltage; a capacitor 12 storing the DC voltage; a converter section 15 having a voltage conversion function section 13 voltage-converting the DC voltage and an output limit function section 14; a second rectifier circuit section 17 receiving an output of the converter section 15 via a transformer 16; and an output section 20 supplying the output voltage from the second rectifier circuit section 17 to loads 18 and 19. The power-supply device causes the output limit function section 14 to perform when receiving an excessive power request from the loads 18 and 19 and detecting the interruption of the AC input.

Description

  The present invention relates to a power supply device used for various electronic devices.

  Hereinafter, a conventional power supply device will be described with reference to the drawings. FIG. 8 is a circuit block diagram showing the configuration of a conventional power supply apparatus. The first rectifier circuit 2 connected to the AC power source 1, the converter 3 connected to the first rectifier circuit 2, and the output of the converter 3 are connected to the transformer 4. And a plurality of loads 6 and 7 for supplying electric power from the second rectifier circuit 5.

  When the capacitor 8 is connected between the first rectifier circuit 2 and the converter 3 and the AC power supply 1 is suddenly cut off for some reason, the capacitor 8 is stored in the capacitor 8. By discharging the electric charge, power is supplied to the loads 6 and 7 for a while and then the entire power supply device is stopped.

  For example, Patent Document 1 is known as prior art document information relating to the invention of this application.

JP 2007-60822 A

  However, in the conventional power supply device, when the supply of power from the AC power supply 1 is interrupted, when it is attempted to stop the operation while supplying power to the loads 6 and 7, it is necessary to control the time for supplying this power. There is a problem that it is required to individually change the capacitance of the capacitor 8 at the time of design according to the time setting. In addition, particularly when an attempt is made to extend the supply of electric power, it is necessary to increase the capacity of the capacitor 8, and accordingly, there is a problem that an increase in the volume of the power supply device and a large increase in cost related to the capacitor 8 occur. there were.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply device that can easily control power supply during interruption.

  In order to achieve this object, the power supply apparatus of the present invention includes an AC input unit, a first rectifier circuit unit that rectifies an AC input from the AC input unit and outputs a DC voltage, and stores the DC voltage. A capacitor having a voltage converting function, a voltage converting function part for converting the DC voltage, and an output limiting function part, a second rectifier circuit part for inputting the output of the converter part via a transformer, and the second rectification An output unit for supplying an output voltage from the circuit unit to a load, and operating the output limiting function when receiving an excessive power request from the load and detecting an AC input interruption. It is a feature.

  According to the present invention, it is possible to easily control the voltage value and the duration of the power supply at the time of handling the interruption, and at the same time, it is possible to reduce the cost and the volume of the power supply device as the capacity of the capacitor for power storage is reduced. Is.

Circuit block diagram of the power supply device of the present invention First voltage output waveform diagram of power supply circuit of the present invention Second voltage output waveform diagram of the power supply circuit of the present invention Third voltage output waveform diagram of the power supply circuit of the present invention First circuit diagram of the power supply circuit of the present invention Fourth voltage output waveform diagram of the power supply circuit of the present invention Second circuit diagram of the power supply circuit of the present invention Circuit block diagram of conventional power supply

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a circuit block diagram showing a configuration of a power supply device according to an embodiment of the present invention. The power supply apparatus includes an AC input unit 10 connected to an AC power source 9 as a primary circuit, a first rectifier circuit unit 11 that rectifies an AC input from the AC input unit 10 and outputs a DC voltage, and a first rectifier circuit. The storage capacitor 12 for storing the DC voltage from the unit 11, the voltage conversion function unit 13 for converting the DC voltage from the first rectifier circuit unit 11, and the output limiting function unit 14 for limiting the output below the limit. And a primary winding 16 a of a transformer 16 connected to the output side of the converter unit 15.

  The secondary circuit includes a second rectifier circuit unit 17 that receives an input from the secondary winding 16b of the transformer 16, and an output unit that supplies the output voltage from the second rectifier circuit unit 17 to the loads 18 and 19. 20.

  The output limiting function unit 14 is operated when an excessive power request from the loads 18 and 19 is received and when it is detected that the AC power supply from the AC power supply 9 is cut off. The output limiting function unit 14 has a function of limiting the output from the converter unit 15 to a limit or less as described above, and the output waveform shown in FIG. A value (Vlim) is provided.

  The operation of the converter unit 15 shown in FIG. 1 performs a switching operation while constantly monitoring the voltage and current in the output unit 20 in order to maintain the voltage required by the loads 18 and 19. Here, for example, when the load 18, 19 or any one of them is very large, that is, requires a large current supply, the power supply time by switching (the width of the waveform per one) is lengthened. Although the converter unit 15 tries to operate so as to be able to cope with a large amount of power, this time becomes too long, and if the maximum portion of the waveform shown in FIG. 2 exceeds a predetermined value, stable power supply is continued. There will be a fear that it will be impossible. Therefore, as a function for controlling the output, an upper limit value (Vlim) is provided in the output waveform, and a voltage higher than that value is not output.

  Here, in addition to the above operations and functions, the operation is performed so as to limit the output even when the AC power supply 9 shown in FIG. 1 is cut off from the power supply device. When the AC power supply 9 is cut off from the power supply device, the supply of power to the output unit 20 is not stopped at that moment, and the supply of power is accumulated in the storage capacitor 12 for a certain predetermined period. It will be continued by the charged charge. For example, when the load 18 is a large load, the load 19 is operated as a voltage conversion function, and power is supplied from here to the microcomputer 21 which is a small power load, the microcomputer 21 operates with a small power. It is easy to continue the operation, and it is possible to memorize various settings and operation states in the power supply device and other devices during the period in which this power supply is possible, to stop the power supply safely, or that the AC power supply 9 has been cut off. An operation such as display is possible.

  And as the operation | movement of an output limitation when the alternating current power supply 9 is interrupted | blocked, as for the electrical storage capacitor 12 which has stored the electric power for supplying for a predetermined period as an electric charge, supply of the electric power from the 1st rectifier circuit part 11 is carried out. When it stops, the electric charge is discharged to the converter unit 15 at that moment. By discharging this electric charge, the output from the converter unit 15 is finally smoothed through the output unit 20 as shown in FIG. 3, and then a waveform is output. Here, the cutoff upper limit value (Vslim) Is set to a voltage value lower than the upper limit value (Vlim) so that power can be supplied for a long period of time with a limited charge.

  Thus, the voltage Vs at the output unit 20 when the cutoff upper limit value is applied by the converter unit 15 after the AC power source 9 of FIG. 1 is shut down is the normal voltage indicated by a broken line as shown in FIG. Although the voltage is lower than the output voltage as it is, the output can be maintained for a long period. Here, the interruption shown in FIG. 3 is performed so that t1 shown in FIG. 4 which is the time for the output 20 to maintain the voltage (Vload) at which the load 19 and the microcomputer 21 can operate is longer than t2 in the broken line. An upper limit value (Vslim) may be set.

  With the above configuration and operation, even when the storage capacitor 12 having a small and constant capacity is applied, the cutoff upper limit value in the converter unit 15 is set to maintain the voltage at which the load 19 and the microcomputer 21 can operate as an output. Thus, it is possible to easily control and change the power supply at the time of interruption corresponding to a long period.

  At the same time, since it is not necessary to increase the capacity of the storage capacitor 12, the cost associated with the storage capacitor 12 is not increased, and the volume of the power supply device can be suppressed.

  Further, as shown in FIG. 1, as a means for detecting the interruption of the AC power supply 9, the interruption detection unit 22 is provided connected to the AC input unit 10, and an output limiting function is provided from the interruption detection unit 22 when the AC power is interrupted. It is desirable to transmit a signal to the output limiting function unit 14 having the signal. This is because, as described above, the power supply at the time of interruption is performed by the limited charge of the storage capacitor 12 and is not possible in such a long period. Therefore, when the AC power supply 9 is cut off, By transmitting a signal to the output limiting function unit 14 as quickly as possible and switching from the upper limit value (Vlim) to the cutoff upper limit value (Vslim) by this signal, it is possible to further extend the power supply. It is.

  Here, as a means for switching between the upper limit value (Vlim) and the cutoff upper limit value (Vslim) by sending a signal from the interruption detection unit 22 to the output restriction function unit 14, as shown in the first circuit diagram of FIG. This may be dealt with by switching the output limiting function unit 14 when operating the voltage conversion function unit 13.

  As shown in FIG. 1, the voltage conversion function unit 13 has the voltage shown in FIG. 5 with respect to the output voltage of the first rectifier circuit unit 11 that may vary within a certain range at all times, that is, the voltage of the AC power supply 9. In order to stabilize the output from the conversion function unit 13, an output voltage obtained by switching of the switching element 23 is fed back, and the PWM oscillator 24 is controlled based on this voltage.

  Here, as described above, it is also necessary to operate the PWM oscillator 24 so as not to exceed a predetermined voltage value in order to stabilize the power supply. For this reason, the reference voltage E and the feedback voltage in the differential amplifier 25 are required. When the feedback voltage Vf exceeds the limit Vflim, the switching time of the switching element 23 is limited by the PWM oscillator 24.

  Here, the switching of the switching element 23 is performed by the PWM oscillator 24 according to the connection state of the series-connected resistors R1, R2, and R3 for current detection provided between the output side of the switching element 23 and the ground electrode 26. We are going to limit the time. Therefore, an upper limit value (Vlim) or a cutoff upper limit value (Vslim) corresponding to the feedback voltage Vf corresponding to the current detection voltage obtained from the connection point between the output side of the switching element 23 and the resistors R1 and R2 for the operation. Is set.

Specifically, when the power supply device is operating in a normal state, an instruction to close the first voltage dividing switch 27 shown in FIG. 5 is issued from the shutoff detection unit 22 shown in FIG. The upper limit value of the current detection voltage is Vlim (upper limit value) = Vflim × (R1 + R2) / R2.
Will be determined. On the other hand, when the AC power supply 9 shown in FIG. 1 is shut off from the power supply device, the shutoff detection unit 22 instructs to open the first voltage dividing switch 27 shown in FIG. (Shut-off) upper limit value of current detection voltage is Vslim (shut-off upper limit value) = Vflim × (R1 + R2 + R3) / (R2 + R3)
Will be determined. Here, since R1, R2, and R3 are all positive in resistance value, as described above,
Vlim (upper limit value)> Vslim (cutoff upper limit value)
It will also be determined.

  That is, in order to change the determination level for the current detection voltage from the switching element 23, the upper limit value (Vlim) or the cutoff is based on the threshold value Vflim of the feedback voltage Vf that is a reference to be input to the differential amplifier 25 and determined. The upper limit value (Vslim) is determined. Therefore, when the AC power supply 9 shown in FIG. 1 is shut off, a signal is transmitted from the shut-off detection unit 22 to the output limiting function unit 14, and this signal causes the upper limit value (Vlim) shown in FIG. The output upper limit voltage is lowered after switching to Vslim). In response to this, the PWM oscillator 24 shown in FIG. 5 limits the switching time of the switching element 23, thereby suppressing the power supply per unit time and further extending the power supply. is there.

  Further, since one side of the first voltage dividing switch 27 is connected as the ground electrode 26 side, the divided voltage when the first voltage dividing switch 27 is switched is the case where the first voltage dividing switch 27 is ON / OFF. However, since the potential is stable, the upper limit value (Vlim) and the cutoff upper limit value (Vslim) can be strictly defined, and the power supply period can also be set precisely.

  In the embodiments described so far, the correspondence when the AC power supply 9 is shut off by switching the upper limit value (Vlim) of the output in the output limiting function unit 14 shown in FIG. 1 to the cutoff upper limit value (Vslim) has been described. Here, when the AC power supply 9 shown in FIG. 1 is cut off, the upper limit value (Vlim) is not changed, and the peak value of the voltage output waveform shown in FIG. A method for reducing the actual output voltage will be described.

  As shown in FIG. 1, the voltage conversion function unit 13 is shown in FIG. 7 for the output voltage of the first rectifier circuit unit 11 that may vary within a certain range at all times, that is, the output voltage of the AC power supply 9. In order to maintain the stability of the output from the voltage conversion function unit 13, the oscillation state of the switching element 23 is fed back to the voltage obtained by the oscillation of the switching element 23 and controlled by the PWM oscillator 24 based on this voltage. .

  Here, as in the previous case, it is necessary to operate the PWM oscillator 24 so as not to exceed a predetermined voltage value in order to stabilize the power supply. For this purpose, the differential amplifier 25 uses the reference voltage E and the feedback voltage Vf. When the feedback voltage Vf exceeds the limit Vflim, the PWM oscillator 24 limits the oscillation of the switching element 23.

  Here, the oscillation of the switching element 23 is limited by the PWM oscillator 24 in accordance with the connection state of the series-connected resistors R11, R12, and R13 provided between the output terminal of the first rectifier circuit unit 11 and the ground electrode 26. It is something to be made. Therefore, the absolute value of the feedback voltage Vf obtained from the connection point between the output side of the switching element 23 and the resistors R12 and R13, that is, the potential of the resistor R13, is switched.

Specifically, when the power supply device is operating in a normal state, an instruction is issued from the shut-off detection unit 22 shown in FIG. 1 to open the second voltage dividing switch 28 shown in FIG. The feedback voltage Vf is Vf = Vs + Vr × R13 / (R11 + R12 + R13) where Vs is the voltage applied to the above-mentioned connection point from the output voltage for current detection and Vr is the voltage at the output terminal of the first rectifier circuit unit 11.
As given.

On the other hand, when the AC power source 9 shown in FIG. 1 is cut off from the power supply device, the cutoff detection unit 22 instructs to close the second voltage dividing switch 28 shown in FIG. 7, and at this time, the feedback voltage Vf Vf = Vs + Vr × R13 / (R11 + R13)
Will be given as. Here, since R1, R2, and R3 are all positive resistance values, when the AC power source 9 shown in FIG. 1 is shut off, Vf in FIG. 7 is larger than that in the normal state.

  In other words, when the power supply device is operating in a normal state, even when the feedback voltage Vf is lower than the limit Vflim, the AC power supply 9 shown in FIG. A predetermined bias voltage is directly added to the feedback voltage Vf. As a result, the feedback voltage Vf becomes an excessive value exceeding the limit Vflim, and the PWM oscillator 24 shown in FIG. 7 limits the switching time of the switching element 23. As a result, the power supply per unit time is suppressed, and the power supply can be further prolonged.

  Further, when the AC power source 9 shown in FIG. 1 is cut off from the power supply device, and then the AC power source 9 is restored again and AC power is applied to the AC input unit 10, the cutoff detection unit 22 shown in FIG. Instead of issuing a signal for instructing the opening of the second voltage dividing switch 28, which is a signal as a normal operation, delays the instruction for opening the second voltage dividing switch 28 from the shut-off detection unit 22 by providing a predetermined time. It is desirable. As a result, the switching time of the switching element 23 can be limited, and even when the interruption detection unit 22 continuously detects interruption or connection in a short period of time, the load on the switching element 23 is reduced. Thus, stable operation can be maintained as a whole power supply device.

  In the above embodiment, as shown in FIG. 1, the converter unit 15 has a voltage conversion function by using the primary winding 16 a of the transformer 16, but although the transformer 16 is used as an example, The winding 16a may be applied as a choke coil. That is, a rectifying function diode (not shown) in which an output terminal (not shown) is connected in series to an output terminal (not shown) from a connection point between the switching element 23 and the primary winding 16a in FIG. And a smoothing function capacitor (not shown) connected in parallel to the output terminal (not shown), which is led out and replaced as a power supply device by replacing the primary winding 16a with a choke coil (not shown). It does not matter.

  The power supply device of the present invention has an effect of facilitating control of continuation of power supply when the AC power supply is shut off, and is useful in various electronic devices.

DESCRIPTION OF SYMBOLS 9 AC power supply 10 AC input part 11 1st rectifier circuit part 12 Storage capacitor 13 Voltage conversion function part 14 Output restriction function part 15 Converter part 16 Transformer 16a Primary winding 16b Secondary winding 17 2nd rectifier circuit part 18, 19 Load DESCRIPTION OF SYMBOLS 20 Output part 21 Microcomputer 22 Blocking detection part 23 Switching element 24 PWM oscillator 25 Differential amplifier 26 Ground electrode 27 1st voltage dividing switch 28 2nd voltage dividing switch

Claims (4)

AC input section,
A first rectifier circuit that rectifies an AC input from the AC input unit and outputs a DC voltage;
A capacitor for storing the DC voltage;
A converter unit having a voltage conversion function unit for converting the DC voltage into a voltage and an output limiting function unit;
A second rectifier circuit section for inputting the output of the converter section via a transformer;
An output unit for supplying the output voltage from the second rectifier circuit unit to the load,
The output limiting function unit;
A power supply device that operates when receiving an excessive power request from the load and detecting an interruption of an AC input. An interruption detection unit that detects interruption of AC power is connected to the AC input unit,
The power supply device according to claim 1, wherein when the AC power is cut off, a signal is transmitted from the cut-off detection unit to the output restriction function unit. The power supply device according to claim 2, wherein the output upper limit voltage in the output restriction function unit is switched in accordance with a signal from the interruption detection unit. The power supply device according to claim 2, wherein the output limiting function unit is operated by applying an excessive input to the converter unit in accordance with a signal from the shut-off detection unit.

Images