JP3293447B2 - Switching power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply for suppressing an inrush current.

[0002]

2. Description of the Related Art Conventionally, as a device for stabilizing a fluctuation of a DC power supply voltage due to a fluctuation of a load or a fluctuation of an AC input voltage, switching in which a supply current is interrupted by a switching element and a load voltage is controlled by a conduction angle thereof. Power supplies are known. FIG. 8 is a block diagram showing such a switching power supply device.

As shown in FIG. 8, a switching power supply 1 includes a rectifier circuit 10 for rectifying a commercial AC voltage E.
A smoothing capacitor C ₀ for obtaining a DC output from a pulsating current output from the rectifier circuit unit 10, and a switching power supply unit 11 for converting the DC output from the smoothing capacitor C ₀ into a desired voltage.

Accordingly, since the switching power supply device 1 includes the large-capacity smoothing capacitor C ₀ , the rush current and the inrush current may be maintained for a while until the charge is charged in the smoothing capacitor C ₀ when the power switch S is turned on. Large current flows. This inrush current hastens contact wear of the power switch S, causes contact welding, and has various adverse effects.

Therefore, in the conventional switching power supply 1, in order to suppress the inrush current as described above, a current limiting resistor is provided between the power switch S and the rectifier circuit 10 as shown in FIG. R had been inserted.

[0006]

However, in the switching power supply 1 as described above, since the current limiting resistor R is used to suppress the rush current when the power is turned on, useless power loss is reduced. with resulting, in order to eliminate the wasted power loss after the inrush current has disappeared, there is a problem that it is necessary to parallel connected to the current limiting resistor R and the contact output section T _a of the on-delay timer T as bypass Was.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an excellent switching power supply device capable of suppressing an inrush current without causing power loss. Is to do.

[0008]

Since the present invention SUMMARY OF] is to solve the above problems, in the invention of claim 1, wherein, a GTO thyristor for switching the commercial voltage, the GTO Sa
A switching power supply device comprising: a rectifier circuit unit that rectifies an output from the iristor ; a smoothing circuit unit that smoothes an output from the rectifier circuit unit; and a switching power supply unit that converts an output from the smoothing circuit unit to a predetermined voltage. A phase detection unit that detects a phase of the commercial voltage; and a phase control circuit unit that controls a conduction angle to gradually increase a switching conduction angle of the GTO thyristor based on a detection phase of the phase detection unit. It is characterized by the following.

[0009] In the second aspect of the invention, a GTO thyristor for switching the commercial voltage, the GTO Sai
A switching power supply device comprising: a rectifier circuit for rectifying an output from the lister ; a smoothing circuit for smoothing an output from the rectifier circuit; and a switching power supply for converting an output from the smoothing circuit to a predetermined voltage. Ah, the GTO Sai
A current detection unit that detects a current flowing through the lister ,
When the current detected by the current detector reaches a predetermined current, the GT
A current limit control circuit for turning off the O-thyristor and turning it on again.

[0010] In the third aspect of the present invention, a rectifier circuit portion which rectifies the commercial voltage, the GTO thyristor for switching the output from the rectifier circuit portion, the GTO thyristor
A switching power supply device comprising : a smoothing circuit unit for smoothing an output from the switching unit; and a switching power supply unit for converting the output of the smoothing circuit unit to a voltage, wherein the current detection unit detects a current flowing through the GTO thyristor. The GTO thyristor when the current detected by the current detector reaches a predetermined current.
And a current limit control circuit for turning off and turning on the power again.

According to a fourth aspect of the present invention, an inductor is inserted in series at an input stage or an output stage of the rectifier circuit section.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a switching power supply according to the present invention will be described with reference to FIGS. 1 and 2, and a second embodiment will be described with reference to FIGS. The third embodiment will be described in detail with reference to FIGS. 5 and 6, and the fourth embodiment will be described in detail with reference to FIG.

[First Embodiment] FIG. 1 is a block diagram showing a switching power supply unit. FIG. 2 is an explanatory diagram showing a conduction period of the switching element with respect to the commercial power supply voltage. FIG. 2A shows a commercial power supply voltage waveform, and FIG.
Indicates a current waveform flowing from the commercial power supply to the switching power supply device. In FIG. 1, the same reference numerals are given to portions equivalent to those of the switching power supply device described with reference to FIG.

As shown in FIG. 1, the switching power supply 1 comprises a rectifier circuit 10 and a switching power supply 11
, A smoothing capacitor C ₀ corresponding to a smoothing circuit section, a power switch S, a phase detecting section 13, and a phase control circuit section 14.
And a GTO thyristor 15 corresponding to a switching element
And

The power switch S is for inputting the commercial AC voltage E to the switching power supply 1. The phase detector 13 detects a point in time when the commercial AC voltage E becomes exactly zero, that is, a zero-cross point, and outputs a zero-cross signal synchronized with the zero-cross point to the phase controller 14.

The phase control circuit 14 outputs a gate signal based on the zero-cross signal from the phase detector 13 to the GTO thyristor 15. Now, a half-wave of the commercial AC voltage E is expressed as E = V · sin θ (where θ is 0 to 180 degrees)
And the period in which the phase control circuit unit 14 turns on the GTO thyristor 15 is a period from θ ₀ to θ _t ,
Phase control circuit 14, theta ₀ is always fixed in theta ₀ = 0 °, in the theta _t increase over time despite In the initial charge of the power switch S is theta _t ≒ 0 ° Then, the GTO thyristor 15 is controlled so that finally θ _t = 180 degrees is reached.

The GTO thyristor 15 is a gate turn-off
It is called thyristor and can be turned off even when the anode current is flowing, so that a reverse bias is applied between the gate and the cathode. Rectifier circuit 1
0 is configured by a diode bridge, to charge the rectification smoothing capacitor C ₀ of the output of the GTO thyristor 15. Switching power supply unit 11 outputs the DC output charged in the smoothing capacitor C ₀ into a desired voltage.

The internal circuits of the switching power supply 1 are connected as follows. That is, the input terminal T 1 of the switching power supply ₁ is connected to _one input of the phase detector 13, one input of the phase control circuit 14, and the input of the GTO thyristor 15 via the power switch S. Connecting. The output of the GTO thyristor 15 is connected to one input of the rectifier circuit 10. The input terminal T ₂ of the switching power supply 1 is connected to the other input of the phase detector 13, the other input of the phase control circuit 14, and the other input of the rectifier circuit 10.

One output of the rectifier circuit 10 is connected to one end of a smoothing capacitor C ₀ and one input of a switching power supply 11. The other output of the rectifier circuit 10 is connected to the other end of the smoothing capacitor C _{0 and} the other input of the switching power supply 11. One output of the switching power supply 11 is connected to the output terminal T ₃ of the switching power supply 1, and the other output of the switching power supply 11 is connected to the output terminal T ₂ of the switching power supply 1. Further, the signal output section of the phase detection section 13 is connected to the signal input section of the phase control circuit section 14, and the phase control circuit section 14
Are connected to the gate of the GTO thyristor 15.

The switching power supply 1 described above is as follows.
Works. That is, when the power switch S is turned on,
The phase detector 13 detects the zero cross point of the commercial AC voltage E
And sequentially outputs a zero-cross signal to the phase control circuit unit 14.
You. As shown in FIG. 2, the phase control circuit 14
Zero cross point θ for each half-wave of source voltage E₀From θ_tUntil
Signal that turns on the GTO thyristor 15 during
Output. Moreover, θ _tTurned on the power switch S
At the beginning (θ_t−θ₀) ≒ 0 degrees, and time passes
(Θ_t−θ₀) Increases, and eventually
When the state is ON, that is, (θ_t−θ₀) = 180 degrees
And reaches saturation.

Accordingly, the smoothness at the beginning of turning on the power switch S is
Capacitor C₀Is not charged at all
However, the commercial power supply voltage E is supplied via the GTO thyristor 15
Smoothing capacitor C₀Is very low.
Therefore, the smoothing capacitor C ₀Only a small current flows into
do not do. Then, (θ_t−θ₀) Gradually increases and GT
Smoothing capacitor C via O-thyristor 15₀Applied to
The smoothing capacitor C₀Is it
The battery is charged with a charge appropriate for
A situation where an input current flows does not occur.

That is, in the switching power supply device 1 described above, an inrush current when the power switch S is turned on can be prevented, and the GTO thyristor 15 acts as a switch for turning on and off, so that no power loss occurs. .

[Second Embodiment] FIG. 3 is a block diagram showing a switching power supply unit. 4A and 4B are explanatory diagrams showing current waveforms flowing from the commercial power supply to the switching power supply device. FIG. 4A shows a state immediately after the power switch is turned on, and FIG. The state of is shown. In FIG. 3, the same reference numerals are given to the same portions as those of the switching power supply device described with reference to FIG. 8 in the related art.

As shown in FIG. 3, the switching power supply 1 includes a rectifier circuit 10 and a switching power supply 11
When a smoothing capacitor C ₀ which corresponds to the smoothing circuit, and a power switch S, a current detector 16, a current limiting control circuit section 17, and a GTO thyristor 15 which corresponds to the switching element.

The power switch S is for inputting the commercial AC voltage E to the switching power supply 1. The current detector 16 detects the current i flowing into the switching power supply 1 via the power switch S, and outputs an output signal proportional to the absolute value of the current i to the current limit control circuit 17.

The current limiting control circuit 17, when exceeding a predetermined upper limit current value I ₀ in which the absolute value is set in advance of the gate signal has been outputted, current i to turn on the GTO thyristor 15 is in the normal , A gate signal for turning off the GTO thyristor 15 is output. Incidentally, GTO thyristor 15, rectifier circuit 10, the switching power supply unit 11 and the smoothing capacitor C _0, since it is the same as that described in the first embodiment, and detailed description thereof will be omitted.

The internal circuits of the switching power supply 1 are connected as follows. That is, the input terminal T 1 of the switching power supply ₁ is connected to one input of the current limit control circuit 17 and the input of the GTO thyristor 15 via the power switch S and the current detector 16 in series. . The output of the GTO thyristor 15 is
To one of the input sections. The input terminal T ₂ of the switching power supply 1 is connected to the other input of the current limit control circuit 17 and the other input of the rectifier circuit 10.

One output of the rectifier circuit 10 is connected to one end of a smoothing capacitor C ₀ and one input of a switching power supply 11. The other output of the rectifier circuit 10 is connected to the other end of the smoothing capacitor C _{0 and} the other input of the switching power supply 11. One output of the switching power supply 11 is connected to the output terminal T ₃ of the switching power supply 1, and the other output of the switching power supply 11 is connected to the output terminal T ₄ of the switching power supply 1. Further, the signal output section of the current detection section 16 is connected to the signal input section of the current limit control circuit section 17, and the signal output section of the current limit control circuit section 17 is connected to the gate of the GTO thyristor 15.

The above-described switching power supply 1 operates as follows. That is, when the power switch S is turned on,
The input current i is determined by the current detector 16 and the GTO thyristor 15.
And the rectifier circuit section 10 and flows into the smoothing capacitor C ₀ . Further, the current detection unit 16 detects the current i and outputs an output signal proportional to the absolute value of the current i to the current limit control circuit unit 17. The current limit control circuit 17 is a gate for turning off the GTO thyristor 15 when the absolute value of the current i exceeds a predetermined upper limit current value I ₀ based on the output signal from the current detector 16. Output a signal,
When the GTO thyristor 15 is turned off by the gate signal and the current i becomes zero, a gate signal for turning on the GTO thyristor 15 is output again.

Therefore, immediately after the power switch S is turned on, almost no charge is charged in the smoothing capacitor C ₀ , and the GTO thyristor 15 operates in the current limit control circuit 1.
7 is not controlled by the gate signal from
Represents the current i in a period in which the current exceeds the upper limit current value I ₀ , for example, in periods t _1, t _{2 and} t ₃ in FIG.
Has a saw-tooth shape with the current value I ₀ being the upper limit as shown in FIG. After that, when some time elapses, is charged charges the smoothing capacitor C _0, it increases the voltage of the smoothing capacitor C ₀ is short and the voltage difference period exceeding the voltage of the output voltage smoothing capacitor C ₀ of the rectifier circuit 10 is Since the current i almost disappears, the current i always falls below the upper limit current value I _0, and the waveform of the current i is as shown in FIG. 4B. If no current is being supplied to the load, the current i will eventually be zero.

That is, the smoothing capacitor C ₀ is not charged at all when the power switch S is turned on, and the current i is originally an inrush current and the upper limit current value I ₀
Even if you have to flow beyond
The current i is limited by the upper limit current value I ₀ as described above, and it is possible to prevent an inrush current when the power switch S is turned on,
Since the GTO thyristor 15 acts as a switch for turning on and off, no power loss occurs.

[Third Embodiment] FIG. 5 is a block diagram showing a switching power supply unit. FIG. 6 is an explanatory diagram showing a waveform of a current flowing from the rectifier circuit to the smoothing circuit unit. FIG. 6A shows a state immediately after the power switch is turned on.
(B) shows a state at a point in time when the power switch is turned on. In FIG. 5, the same parts as those of the switching power supply according to the second embodiment described with reference to FIG. 3 are denoted by the same reference numerals, and the detailed description of the same parts will be omitted.

As shown in FIG. 5, this switching power supply device 1 is different from the switching power supply device of the second embodiment described with reference to FIG. The configuration includes a current detection unit 16, a current limit control circuit unit 17, and a GTO thyristor 15 corresponding to a switching element.

The internal circuits of the switching power supply 1 are connected as follows. That is, the input terminal T ₁ of the switching power supply unit 1 is connected to one input of the rectifier circuit portion 10 through the power switch S. The input terminal T ₂ of the switching power supply 1 is connected to the other input of the rectifier circuit unit 10. One output unit of the rectifier circuit unit 10 includes:
It is connected to one input of the current limit control circuit 17 and the input of the GTO thyristor 15 via the current detector 16. The output of the GTO thyristor 15 is connected to one end of the smoothing capacitor C ₀ and one input of the switching power supply 11. The other output of the rectifier circuit 10 is connected to the other input of the current limiting control circuit section 17, and the other end of the smoothing capacitor C _0, to the other input of the switching power supply unit 11. One output of the switching power supply 11 is connected to the output terminal T ₃ of the switching power supply 1, and the other output of the switching power supply 11 is connected to the output terminal T ₄ of the switching power supply 1. Further, the signal output section of the current detection section 16 is connected to the signal input section of the current limit control circuit section 17, and the signal output section of the current limit control circuit section 17 is connected to the gate of the GTO thyristor 15.

The switching power supply 1 operates as follows. That is, when the power switch S is turned on,
The input current i flows into the smoothing capacitor C ₀ via the power switch S, the rectifier circuit 10, the current detector 16, and the GTO thyristor 15. Further, the current detection unit 16 detects the current i and outputs an output signal proportional to the absolute value of the current i to the current limit control circuit unit 17. Current limit control circuit 1
Reference numeral 7 denotes a predetermined upper limit current value I ₀ in which the absolute value of the current i is set in advance based on the output signal from the current detector 16.
, A gate signal for turning off the GTO thyristor 15 is output when the GTO thyristor 15 is turned off.
Is turned off, and when the current i becomes zero, a gate signal for turning on the GTO thyristor 15 is output again.

Therefore, immediately after the power switch S is turned on, almost no charge is charged in the smoothing capacitor C ₀ , and the GTO thyristor 15 is connected to the current limit control circuit 1.
7 is not controlled by the gate signal from
Represents the current i in a period in which the current exceeds the upper limit current value I ₀ , for example, in periods t _1, t _{2, and} t ₃ in FIG.
Has a sawtooth shape with the current value I ₀ as the upper limit as shown in FIG. After that, when some time elapses, is charged charges the smoothing capacitor C _0, it increases the voltage of the smoothing capacitor C ₀ is short and the voltage difference period exceeding the voltage of the output voltage smoothing capacitor C ₀ of the rectifier circuit 10 is Since the current i almost disappears, the current i is always lower than the upper limit current value I _0, and the waveform of the current i is as shown in FIG. 6B. If no current is being supplied to the load, the current i will eventually be zero.

The current waveform in FIG. 6 is an explanatory diagram of the waveform of the current i flowing from the rectifier circuit to the smoothing capacitor, and is shown as a waveform after full-wave rectification. Also in this case, the current waveform at the power switch S is
The waveform is similar to the waveform shown in FIG. In addition, since the GTO thyristor 15 is provided at the subsequent stage of the rectifier circuit section 10, there is an advantage that the GTO thyristor 15 does not need to be bidirectional.

Accordingly, the smoothing capacitor C ₀ is not charged at all when the power switch S is turned on, and the current i is originally an inrush current and the upper limit current value I ₀
Even if you have to flow beyond
The current i is limited by the upper limit current value I ₀ as described above, and it is possible to prevent an inrush current when the power switch S is turned on,
Since the GTO thyristor 15 acts as a switch for turning on and off, no power loss occurs.

Fourth Embodiment FIG. 7 is a block diagram showing a switching power supply. In FIG. 7, the same reference numerals are given to the same parts as those of the switching power supply according to the second embodiment described with reference to FIG. 3, and the detailed description of the same parts will be omitted.

As shown in FIG. 7, this switching power supply device 1 is different from the switching power supply device of the second embodiment described with reference to FIG. 3 in that the switching power supply device 1 has a GTO thyristor 15 corresponding to a switching element. Rectifier circuit 1
This is a configuration in which an inductance L is inserted between 0 and 0.

The internal circuits of the switching power supply 1 are connected as follows. That is, the input terminal T 1 of the switching power supply ₁ is connected to one input of the current limit control circuit 17 and the input of the GTO thyristor 15 via the power switch S and the current detector 16 in series. . The output of the GTO thyristor 15 is connected to one input of the rectifier circuit 10 via an inductance L.
The input terminal T ₂ of the switching power supply 1 is connected to the other input of the current limit control circuit 17 and the other input of the rectifier circuit 10.

One output of the rectifier circuit 10 is connected to one end of the smoothing capacitor C ₀ and one input of the switching power supply 11. The other output of the rectifier circuit 10 is connected to the other end of the smoothing capacitor C _{0 and} the other input of the switching power supply 11. One output of the switching power supply 11 is connected to the output terminal T ₃ of the switching power supply 1, and the other output of the switching power supply 11 is connected to the output terminal T ₄ of the switching power supply 1. Further, the signal output section of the current detection section 16 is connected to the signal input section of the current limit control circuit section 17, and the signal output section of the current limit control circuit section 17 is connected to the gate of the GTO thyristor 15.

The above-described switching power supply device 1 operates as follows. That is, when the power switch S is turned on,
The input current i is determined by the current detector 16 and the GTO thyristor 15.
And via an inductance L and a rectifier circuit portion 10, and flows into the smoothing capacitor C _0. In addition, the current detection unit 16
The current i is detected, and an output signal proportional to the absolute value of the current i is output to the current limit control circuit 17. The current limit control circuit 17 is configured to output the current
Outputs a gate signal for turning off the GTO thyristor 15 when the absolute value of the current i exceeds a predetermined upper limit current value I ₀ which is set in advance, the zero current i off GTO thyristor 15 in the gate signal Then, a gate signal for turning on the GTO thyristor 15 is output again.

As is clear from the above description, FIG.
In the switching power supply 1 of the second embodiment, the operation is substantially the same as that of the switching power supply of the second embodiment shown in FIG. However, since the inductance L exists, when the GTO thyristor 15 limits the current i in a sawtooth shape with the current value I ₀ as an upper limit by the current limit control circuit section 17, the rate of change in the rise and fall of the current i is reduced. The ON / OFF cycle of the GTO thyristor 15 when the current i is limited to a saw-tooth shape becomes longer than in the case of the switching power supply device shown in FIG. 3 of the second embodiment. As a result,
High frequency noise can be reduced and the life of the smoothing capacitor C ₀ can be extended.

In the switching power supply device 1 shown in FIG. 7, the inductance L is inserted between the GTO thyristor 15 and the rectifier circuit unit 10;
The same effect can be obtained by inserting between the power supply switch S and the GTO thyristor 15 or between the power supply switch S and the smoothing capacitor C ₀ . Also, in the switching power supply device of the third embodiment shown in FIG. 5, the same effect can be obtained by inserting the inductance L.

[0046]

According to the first to third aspects of the present invention, since the ON / OFF of the switching element is used instead of using the resistor for limiting the inrush current, the transient state until the current becomes a steady state is achieved. Even if there is no power loss, there is an effect that an excellent switching power supply device can be provided, in which it is not necessary to separately provide a bypass path or the like after the steady state.

According to the fourth aspect of the present invention, in addition to the above-mentioned effects, the current waveform flowing into the smoothing capacitor at the time of turning on the power can be made somewhat smooth, so that the excellent switching which can extend the life of the smoothing capacitor can be achieved. There is an effect that a power supply device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a switching power supply according to the present invention.

FIG. 2 is an explanatory diagram showing a conduction period of a switching element in the switching power supply device.

FIG. 3 is a block diagram showing a switching power supply device according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an input current waveform in the switching power supply device.

FIG. 5 is a block diagram showing a third embodiment of the switching power supply device according to the present invention.

FIG. 6 is an explanatory diagram showing a waveform of a current flowing into a smoothing circuit unit in the switching power supply device.

FIG. 7 is a block diagram showing a fourth embodiment of the switching power supply device according to the present invention.

FIG. 8 is a block diagram showing a conventional switching power supply device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 switching power supply device 10 rectifier circuit unit 11 switching power supply unit 13 phase detection unit 14 phase control circuit unit 15 switching element 16 current detection unit 17 current limit control circuit unit C ₀ smoothing circuit unit E commercial voltage L inductance

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Satoshi Kajiyama 1048 Kazuma Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (56) References JP-A-2-2416363 (JP, A) JP, A) JP-A-2-309410 (JP, A) JP-A-1-152965 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02M 7/155 G05F 1/10 H02M 1/08 H02M 7/06 H03K 17/725

Claims (4)

(57) [Claims] 1. A GTO circuit for switching a commercial voltage
And Lister, a rectifier circuit for rectifying the output from said GTO thyristor, a smoothing circuit for smoothing an output from the rectifier circuit portion, a switching power supply unit for converting an output from the smooth circuit to a predetermined voltage A phase detection unit for detecting a phase of a commercial voltage, and a phase control circuit for controlling a conduction angle to gradually increase a switching conduction angle of the GTO thyristor based on a detection phase of the phase detection unit. And a switching power supply device. 2. A GTO circuit for switching a commercial voltage.
And Lister, a rectifier circuit for rectifying the output from said GTO thyristor, a smoothing circuit for smoothing an output from the rectifier circuit portion, a switching power supply unit for converting an output from the smooth circuit to a predetermined voltage a switching power supply device comprising: a current detector for detecting current flowing through the GTO thyristor, a current limit control the detected current of the current detection unit is turned on again off the GTO thyristor reaches a predetermined current A switching power supply device comprising a circuit portion. 3. A rectifier circuit for rectifying a commercial voltage, and a GTO thyristor for switching an output from the rectifier circuit.
Through the motor, and a smoothing circuit for smoothing an output from said GTO thyristor, a switching power supply and a switching power supply unit for voltage conversion of the output of the smooth circuit unit, a front <br/> SL GTO thyristor A switching power supply, comprising: a current detection unit for detecting a current flowing into the GTO thyristor when the detection current of the current detection unit reaches a predetermined current; apparatus. 4. The switching power supply device according to claim 2, wherein an inductance is inserted in series at an input stage or an output stage of the rectifier circuit unit.