JPH0515148A - Power supply device - Google Patents

Abstract

PURPOSE:To quickly raise a power unit immediately after the power supply is made to the unit. CONSTITUTION:When a plurality of power output sections 191-193 is connected in cascade, a control circuit 196 applies servo until the output voltage of the power output section in the prestage becomes higher than a preset prescribed reference voltage. When the output voltage of the power output section in the prestage reaches the prescribed value, the output voltage of the power output section in the poststage is supplied to the circuit 196 and the circuit 196 applies servo so as to make the output voltage of the power output section in the prestage constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device suitable for application when a combination of two or more power supply output sections such as a switching power supply circuit and a DC-DC converter is used.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a configuration in which a plurality of stages of power supply output sections are vertically connected. In this example, the commercial AC voltage is rectified by the rectifying / smoothing circuit 1 by the diode bridge circuit 11, and the DC voltage smoothed by the capacitor 12 is supplied to the switching power supply circuit 2 in the subsequent stage. In the switching power supply circuit 2, the voltage supplied from the rectifying / smoothing circuit 1 is switched by the NPN transistor 21 controlled by the control circuit 22, and the transformer 2
At 3, the switching output is boosted, for example. The output of the transformer 23 is rectified by the diode 24 and then smoothed by the capacitor 25.

The output of the switching power supply circuit 2 is further output to the DC-DC converter circuit 3 and the stabilizing circuit 4 in the subsequent stage.

In the converter circuit 3, the DC voltage supplied from the switching power supply circuit 2 is supplied to the transformer 35.
The NPN transistor 33, to which the capacitor 34 is connected in parallel via the primary coil of, is received, and the NPN transistor 33 is switched by the oscillation pulse output from the oscillator (OSC) 32. The output of the transformer 35 is rectified by the diode 36, smoothed by the capacitor 37, and output. The voltage smoothed and output by the capacitor 37 is detected by the detection circuit 31, and the switching power supply circuit 2
Is supplied to the control circuit 22.

The control circuit 22 controls the switching of the NPN transistor 21 so that the detection voltage detected by the detection circuit 31 becomes a constant voltage.

On the other hand, the DC voltage output from the switching power supply circuit 2 is the NPN transistor 4 of the stabilizing circuit 4.
3 and the choke coil 45. The diode 44 is connected to one end of the choke coil 45, and the capacitor 46 is connected to the other end. The output voltage of the capacitor 46 is detected by the detection circuit 41 and supplied to the control circuit 42. The control circuit 42 performs switching control of the NPN transistor 43 in accordance with the voltage supplied from the detection circuit 41, and controls the output voltage to be a constant value.

When a plurality of power supply output sections are connected in cascade as in this example, in order to stabilize the output voltage in this system, the output voltage of the final stage is monitored so that the output becomes constant. It is preferable to apply a servo. However, since the output voltage of the former stage is supplied to the latter stage, the output voltage of the latter stage is delayed as compared with the output voltage of the former stage. In the case of this example, since the DC voltage output from the switching power supply circuit 2 in the front stage is supplied to the converter circuit 3 in the rear stage, the output voltage of the converter circuit 3 is delayed as compared with the output voltage of the switching power supply circuit 2. ..

As a result, even after the voltage output from the switching power supply circuit 2 reaches a predetermined voltage, the converter circuit 3
Since the voltage output by the switch has not reached the predetermined voltage, the control circuit 22 keeps the switching power supply circuit 2 in the meantime.
The NPN transistor 21 is controlled so that the output voltage of the NPN transistor 21 becomes larger. Therefore, as shown in FIG. 6, the output voltage of the switching power supply circuit 2 in the preceding stage becomes unnecessarily higher than the normal voltage.

Therefore, in the conventional device, as shown in FIG. 7, the output of the switching power supply circuit 2 in the front stage rises relatively slowly, and the converter circuit 3 in the rear stage.
The output of was adjusted so that it could rise relatively quickly.

[0010]

However, in the conventional device, since the output voltage of the front stage gradually rises as compared with the output voltage of the rear stage, it takes time to start up (predetermined from the final stage). It takes a long time until the voltage is output).

The present invention has been made in view of such a situation, and is intended to improve its rising characteristic.

[0012]

A power supply device of the present invention detects an output voltage of a power supply output unit of a front stage and a power supply output unit of a rear stage in a power supply circuit having a plurality of power supply output units cascade-connected. When the output voltage of the power supply output unit of the preceding stage is smaller than a predetermined value in correspondence with the output of the detection unit, the control unit that controls the output voltage of the power supply output unit of the preceding stage corresponding to the detected voltage, and the output of the detection unit, The output voltage of the power supply output unit of the previous stage is supplied to the control means as a detection voltage, and when it is larger than a predetermined value,
And a switching means for switching so that the output voltage of the power supply output section at the latter stage is supplied to the control means as a detection voltage.

[0013]

In the power supply device having the above configuration, the output voltage of the power supply output unit of the preceding stage is controlled with the output voltage of the power supply output unit of the preceding stage as a reference until the output voltage of the power supply output unit of the preceding stage reaches a predetermined value. When the output voltage is equal to or higher than a predetermined value, the output voltage of the power supply output unit in the preceding stage is controlled with reference to the output voltage of the power supply output unit in the subsequent stage. Therefore, the rise of the output voltage can be accelerated.

[0014]

1 is a circuit diagram showing the configuration of an embodiment of a power supply device of the present invention. In the present embodiment, the switching power supply circuit 60 is connected to the subsequent stage of the rectifying / smoothing circuit 50 having the diode bridge circuit 51 and the smoothing capacitor 52. The switching power supply circuit 60 includes a diode 61, a capacitor 62, a choke coil 63,
It is composed of an NPN transistor 64 and a control circuit 65.

DC is provided after the switching power supply circuit 60.
A DC converter circuit 70 is connected. The converter circuit 70 includes a transformer 83 to which the DC voltage supplied from the switching power supply circuit 60 is supplied to the primary coil 75, and an NPN connected to the other end of the primary coil 75.
Transistor 72, diode 73 and capacitor 7
And an oscillating circuit (OSC) 7 for outputting a predetermined oscillating pulse to the base of the NPN transistor 72.
1, a diode 77 for rectifying the output voltage of the secondary coil 76 of the transformer 83, and a capacitor 78 for smoothing the output. Also, this transformer 83
A second secondary coil 80 is also connected to the capacitor 8. After the output is rectified by the diode 81, the capacitor 8
It is smoothed by 2 and output. In addition, a coil 79 as a tertiary coil is connected to the transformer 83, and a predetermined AC voltage is output from the output terminal of the coil 79.

A light emitting diode 91 and a photocoupler 91 composed of a phototransistor 92 are connected as a detection circuit 90 for detecting the output voltage of the switching power supply circuit 60. Further, a light emitting diode 101 as a detection circuit 100 for detecting the output voltage of the converter circuit 70,
Photocoupler 103 composed of phototransistor 102
Are connected.

A switching circuit 110 for switching the operation is connected to the subsequent stage of the detection circuits 90 and 100. This switching circuit 110 includes a tertiary coil 111 that forms a part of the transformer 83, a diode 112 that rectifies the output of the tertiary coil 111, and a capacitor 11 that smoothes the output of the tertiary coil 111.
3 and the emitter is connected to the phototransistor 92,
PNP transistor 115 whose collector is grounded
And a capacitor 1 at the base of the PNP transistor 115.
It is composed of resistors 114 and 119 for dividing and applying the voltage of 13. In addition, the phototransistor 102
The collector of the NPN transistor 118 is connected to the emitter thereof, and the voltage of the capacitor 113 is divided by the resistors 116 and 117 and applied to the base of the NPN transistor 118 whose emitter is grounded.

Next, the operation will be described. The commercial AC voltage rectified by the diode bridge circuit 51 is smoothed by the capacitor 52 and output as a DC voltage. The switching power supply circuit 60 includes a control circuit 65.
The NPN transistor 64 is turned on and off by the PWM signal output by the. As a result, the switching power supply circuit 6
A predetermined DC voltage is output from 0.

The amount of light emitted from the light emitting diode 91 of the detection circuit 90 changes according to this output voltage. The impedance of the phototransistor 92 is equal to that of the light emitting diode 91.
Changes in accordance with the amount of light emitted by. Now, for example, if it is just after the start-up, the voltage output by the converter circuit 70 has not yet reached the predetermined value. At this time, the PNP transistor 115 is on because its base is grounded via the resistor 114. On the contrary, the NPN transistor 118 is off because its base is grounded through the resistor 116. Therefore, a signal corresponding to the output voltage of the switching power supply circuit 60 detected by the detection circuit 90 is input to the control circuit 65. The control circuit 65 changes the pulse width of the PWM signal output to the NPN transistor 64 in response to this input signal. In this way, the DC voltage output from the switching power supply circuit 60 gradually increases.

The oscillator circuit 71 turns on and off the NPN transistor 72 in a predetermined cycle to switch the output voltage of the switching power supply circuit 60 supplied to the primary coil 75 of the transformer 83. In response to this switching, a voltage is output from the secondary coil 76 of the transformer 83. This output voltage is rectified by the diode 77, smoothed by the capacitor 78, and output.

This output voltage is supplied to the detection circuit 100 and controls the amount of light emitted from the light emitting diode 101. As a result, the impedance of the phototransistor 102 changes according to the amount of light emitted from the light emitting diode 101. When the voltage output from the transformer 83 reaches a predetermined value, the terminal voltage of the capacitor 113 obtained by rectifying the voltage output from the coil 111 with the diode 112 also reaches a predetermined value. As a result, PNP transistor 1
15 turns off, and conversely the NPN transistor 118 turns on. As a result, the operation of the phototransistor 92 is substantially prohibited, and the output of the phototransistor 102 is supplied to the control circuit 65. As a result, thereafter, the control circuit 65 controls the NPN transistor 64 so that the output voltage of the converter circuit 70 becomes a predetermined voltage.

The above operation is graphically shown in FIG. That is, immediately after the power is turned on, the output voltage of the switching power supply circuit 60 arranged in the preceding stage gradually rises, and when the voltage reaches a predetermined value, the reference output voltage is the converter circuit 70 in the latter stage. Output voltage. As a result, thereafter, servo is applied so that the output voltage of the converter circuit 70 reaches a predetermined value. The switching from the phototransistor 92 to the phototransistor 102 is performed before the output voltage of the switching power supply circuit 60 reaches a predetermined standard voltage. Therefore, when servo is applied so that the output voltage of the switching power supply circuit 60 becomes constant with the output voltage of the converter circuit 70 in the subsequent stage as a reference, the output voltage of the switching power supply circuit 60 becomes larger than the standard voltage. Is prevented.

Next, after a predetermined voltage is output from the converter circuit 70 in the subsequent stage as described above,
For example, if the output voltage of the converter circuit 70 drops for some reason, the voltage at the capacitor 113 drops. This turns off the NPN transistor 118 and turns on the PNP transistor 115 instead. As a result, the phototransistor 10
Instead of 2, the phototransistor 92 is connected to the control circuit 65. Therefore, the converter circuit 7 in the subsequent stage
It is possible to prevent the servo from being applied such that the output voltage of the switching power supply circuit 60 in the preceding stage becomes abnormally large when 0 has failed.

FIG. 3 shows the configuration of the second embodiment of the power supply device of the present invention. In this embodiment, the converter circuit 140 is connected to the subsequent stage of the switching power supply circuit 130. A detection circuit 180 that detects the output voltage of the switching power supply circuit 130 and a detection circuit 160 that detects the output of the converter circuit 140 are provided. The detection circuits 180 and 160 can be switched by the switching circuit 170.

In the switching power supply circuit 130,
A DC voltage supplied from a circuit (not shown) is supplied to the NPN transistor 132 via the choke coil 131,
The NPN transistor 132 is switched by the PWM signal output from the control circuit 130. The voltage output from the choco coil 131 is the diode 1
It is rectified by 34, smoothed by the capacitor 135, and output.

The DC output voltage of the capacitor 135 is the primary coil 141 of the transformer 150 of the converter circuit 140.
Is supplied to the NPN transistor 142 via.
The NPN transistor 142 in which the diode 143 and the capacitor 144 are connected in parallel is turned on / off by the oscillation pulse output from the oscillation circuit 145. As a result, a voltage is output from the secondary winding 146 of the transformer 150, the voltage is rectified by the diode 147, smoothed by the capacitor 148, and output.
In addition, a tertiary coil 149 is connected to the transformer 150, and a predetermined AC voltage is output from this coil.

The output voltage of the switching power supply circuit 130 is divided by the resistors 181 and 182 of the detection circuit 180, and the divided voltage is supplied to the control circuit 133 via the diode 183. Therefore, the control circuit 133 switches the NPN transistor 132 in response to the output of the detection circuit 180 immediately after the power is turned on, and controls the output voltage of the switching power supply circuit 130 to be constant.

At this time, a sufficient voltage is not yet induced in the coil 171 as the tertiary coil of the transformer 150. Therefore, the terminal voltage of the capacitor 174 is also small, and the NPN transistor 175 is off.

On the other hand, the primary coil 141 of the transformer 150
When the DC voltage supplied to the coil reaches a predetermined voltage, the voltage output by the coil 171 increases. This voltage is rectified by the diode 172 and charges the capacitor 174. As a result, the charging voltage of the capacitor 174 rises and the NPN transistor 175 turns on. Therefore, resistance 1
82 is short-circuited, the diode 183 is reverse biased and turned off, and the detection output of the detection circuit 180 is not supplied to the control circuit 133.

On the other hand, the PNP transistor 176
When the terminal voltage of the capacitor 174 is small, the base of the capacitor 174 is turned on because its base is grounded via the resistor 173. Therefore, the resistor 164 is short-circuited and the output of the phototransistor 162 is not supplied to the control circuit 133. However, when the terminal voltage of the capacitor 174 increases, the NPN transistor 175 turns on and at the same time the PN
Since the P transistor 176 is turned off, a voltage corresponding to the current flowing through the phototransistor 162 is generated in the resistor 164, and this voltage is supplied to the control circuit 133. Therefore, the voltage output from the secondary coil 146 of the transformer 150 is rectified by the diode 147, and the output voltage smoothed by the capacitor 148 is supplied to a circuit (not shown), and the light emitting diode 161 corresponds to the output voltage. Is controlled, and the output current of the phototransistor 162 is controlled in accordance with the emitted light amount. As a result, the control circuit 133 controls the output voltage of the switching power supply circuit 130 in accordance with the output voltage of the converter circuit 140. Will be done.

When the output voltage of the converter circuit 140 becomes small for some reason, the NPN transistor 1
Since 75 is turned off and the PNP transistor 176 is turned on, the control circuit 133 corresponds to the voltage obtained by dividing the output voltage of the switching power supply circuit 130 by the resistors 181 and 182, as in the case of starting again. It controls the switching operation of the NPN transistor 132.

Therefore, also in this case, as in the case of FIG. 1, it is assumed that the output voltage of the entire system immediately reaches a predetermined value immediately after the power is turned on and that the converter circuit 140 in the subsequent stage has a failure. Also, the switching power supply circuit 130 at the preceding stage is prevented from causing an abnormal operation.

Although the embodiment of FIGS. 1 and 3 is an embodiment in which two stages of power supply output sections are connected, the present invention is also applicable to the case of connecting three stages (or more) as shown in FIG. Applicable. That is, when the power supply output units 191 to 193 are connected in a vertical direction, the output voltage of each is detected by the detection circuit 194. Then, the detection circuit 194 controls the switch circuit 195 so as to supply the output voltage of the power supply output unit 191 at the first stage to the control circuit 196 until the output voltage reaches a predetermined voltage. Then, when the output voltage of the power output unit 191 of the first stage reaches a predetermined voltage, the switch circuit 195 is controlled so that the output voltage of the power output unit 192 of the second stage is supplied to the control circuit 196. .. further,
When the output voltage of the power supply output unit 192 reaches a predetermined voltage, the switch circuit so that the output voltage of the power supply output unit 193 of the third stage (the final stage in this embodiment) is supplied to the control circuit 196. Control 195. The control circuit 196 controls the output voltage output from the power supply output unit 191 according to the voltage input from the switch circuit 195.

Also in this case, the detection circuit 194 controls the switch circuit 195 when the output voltage of the third-stage power supply output section 193 falls below a predetermined level.
The output of the power supply output unit 192 is supplied to the control circuit 196. Further, when the output voltage of the power output unit 192 of the second stage becomes lower than a predetermined level, the switch circuit 195 supplies the output voltage of the power output unit 191 of the first stage to the control circuit 196. Can be switched.

[0035]

As described above, according to the power supply device of the present invention,
When the output voltage of the power output unit of the previous stage is smaller than a predetermined value, the output voltage of the power output unit of the previous stage is supplied to the control means, and when it is higher than the predetermined value, the output voltage of the power output unit of the subsequent stage is controlled. Since it is supplied to the means, it is possible to prevent the output voltage of the power supply output unit in the previous stage from becoming abnormally large immediately after the power is turned on, and to speed up the rise immediately after the power is turned on. ..

Further, even when the power output of the latter stage is lowered due to a failure of the power source output unit of the latter stage,
It is also possible to prevent an abnormal voltage from being generated in the power supply output unit of the preceding stage and destroying the power supply output unit of the preceding stage.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an embodiment of a power supply device of the present invention.

FIG. 2 is an output characteristic diagram illustrating the operation of the embodiment of FIG.

FIG. 3 is a circuit diagram showing a configuration of a second embodiment of the power supply device of the present invention.

FIG. 4 is a block diagram showing the configuration of a third embodiment of the power supply device of the present invention.

FIG. 5 is a block diagram showing a configuration of an example of a conventional power supply device.

FIG. 6 is an output characteristic diagram illustrating a problem of a conventional power supply device.

FIG. 7 is an output characteristic diagram illustrating a problem of a conventional power supply device.

[Explanation of symbols]

 1 rectifying / smoothing circuit 2 switching power supply circuit 3 converter circuit 4 stabilizing circuit 50 rectifying / smoothing circuit 60 switching power supply circuit 70 converter circuit 90, 100 detection circuit 110 switching circuit

Claims (1)

Claim: What is claimed is: 1. A power supply circuit having a plurality of stages of power supply output sections connected in a cascade connection, and a detection unit for detecting output voltages of the power supply output section of the preceding stage and the power supply output section of the subsequent stage. When the output voltage of the power supply output unit of the preceding stage is smaller than a predetermined value, the control unit controlling the output voltage of the power supply output unit of the preceding stage corresponding to the detected voltage, and the output voltage of the power supply output unit of the preceding stage corresponding to the output of the detection unit, The output voltage of the power supply output unit in the preceding stage is supplied to the control unit as the detection voltage, and when it is larger than a predetermined value, the output voltage of the power supply output unit in the subsequent stage is supplied to the control unit as the detection voltage. A power supply device comprising: switching means for switching.